JP2002311410A - Optical switching element, spatial light modulator and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switching element having simple structure and high durability and capable of being operated at high speed. SOLUTION: An optically transparent light transmission member 11 is provided with an incident surface 12 to make light beams from a light source incident, a total reflection surface 13 to totally reflect the light beams and a light emission surface 14 to emit the totally reflected light beams to the outside. When a formula sinθ1 >=(n2 /n1 ), incident light is totally reflected on the total reflection surface 13 and emitted on the light emission surface 14. When the above formula is not satisfied, for example, a refractive index of a refractive index variable material 15 is changed (increased) by impression of voltage, the incident light is not changed and a part or approximately the entire part of it reaches a reflection control member 16. The refractive index variable material 15 is defined as a liquid crystal/polymer complex formed by distributing and storing a liquid crystal material in the polymer matrix. The light reached the reflection control member 16 is not emitted to all the reflecting directions since its distributing and reflecting direction is changed. Thus, output of the light from the light emission surface 14 is modulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switching element, a spatial light modulator, and a pixel display device, and more particularly, to an optical switching element and a spatial light modulator that have a simple structure, high durability, and operate at high speed. And an image display device using the same.

[0002]

2. Description of the Related Art As an optical switching element, one using liquid crystal is known. FIG. 20 is a diagram for explaining an example. A state in which incident light is transmitted through a polarizing plate (not shown) by controlling the orientation of the liquid crystal by turning on / off a voltage between the transparent electrode 102 and the reflective electrode 103.
04a and the state 104b of blocking incident light can be switched. This makes it possible to control the reflection of light.

However, the response speed of a liquid crystal is several milliseconds to several tens of milliseconds for a normal nematic liquid crystal, and about 100 μs even for a ferroelectric liquid crystal which is said to be high-speed. Optical switching is not possible.

Another technique is disclosed in Japanese Patent Laid-Open No. 11-20 / 1999.
There is a technique disclosed in Japanese Patent Application No. 2222. FIG. 21 is a diagram for explaining the operation of the optical switching element proposed in JP-A-11-202222. A light guide section 120 having a total reflection surface 121 capable of transmitting light by total reflection, and a prism capable of capturing the evanescent light by approaching the extraction surface 131 to the total reflection surface, reflecting the evanescent light, and emitting the light. 130 and a drive unit 14 for driving the optical switching unit
0 are stacked in this order with respect to the light emission direction. The cell on the right side of FIG. 21 shows a state in which the prism 130 is located at a position more than the extraction distance at which the evanescent light leaks by operating the driving unit 140. At this time, the light beam 110 that has propagated through the light guide 120 is totally reflected by the total reflection surface 121 as shown in FIG. 21 and exits rightward in the figure. When the driving unit 140 is not operated, the prism 130 is closer than the extraction distance at which the evanescent light leaks as in the cell on the left side of FIG. Total reflection surface 1 as shown in cell
The light enters the prism 130 without being reflected at 21. The light rays that have entered the prism 130 are reflected by the reflecting surface 132 of the prism.
The light guide portion 1 is reflected as shown by a ray 111 shown in FIG.
The light is transmitted through 20 and emitted.

[0005] In this method, in order to switch between the two states of extraction and non-extraction of evanescent light,
Since a small displacement of about the wavelength of light or less is sufficient, a high-speed response with a low driving voltage can be expected. However, since the structure of the prism 130 as shown in FIG. 21 is complicated, it is difficult to uniformly form a plurality of the same on a substrate with a small size, thereby lowering the manufacturing yield and increasing the cost. There is a problem. Further, when the prism 130 is brought close to the total reflection surface 121, a van der Waals force or a liquid bridging force acts, which causes a problem that the peeling becomes difficult.

Another technique is disclosed in Japanese Patent Application Laid-Open No. 2000-1.
There is a technology disclosed in Japanese Patent No. 71813. FIG.
FIG. 1 is a diagram illustrating a schematic configuration of an optical switching element proposed in Japanese Patent Application Laid-Open No. 2000-171813. Liquid crystal 1 in contact with light guide 150 transmitting light by total reflection
By applying a voltage to 55, the orientation of the liquid crystal molecules is controlled, thereby changing the effective refractive index between a value for extraordinary light and a value for ordinary light. As a result,
It is possible to switch between a state in which the incident light (linearly polarized light) 152 is emitted as the totally reflected light 153 and a state in which the incident light (the linearly polarized light) 152 is transmitted and then changed its direction by the reflection film 154 and emitted as the reflected light 151. In this method, the above-described problem does not occur because there is no mechanical drive unit, but there is a problem similar to that shown in FIG. 20 in terms of operation speed.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides an optical switching element, a spatial light modulator, and an image display device using the same which are simple in structure, have high durability, and operate at high speed. The purpose is to provide. More specifically, (1) To provide an optical switching element having a simple structure, high durability, and high response speed (claim 1);
(2) In addition to the above, to provide an optical switching element with small optical loss (Claim 2), (3) In addition to the above, S /
It is an object of the present invention to provide an optical switching element capable of increasing the N ratio (claim 3).

(4) In addition to the above, to provide an optical switching element which has a small incident angle dependence and can be easily manufactured (claim 4). Providing (claim 5),
(6) To provide an optical switching element capable of higher S / N ratio (Claim 6), and (7) In addition to the above, to provide an optical switching element capable of reducing driving energy (Claim 7). And

(8) To provide an optical switching element capable of reducing driving energy (claim 8).
(9) It is an object of the present invention to provide an optical switching element capable of further reducing driving energy (Claim 9), and (10) In addition to the above, to provide an optical switching element which is easy to manufacture (Claim 10).

(11) Further, to provide a spatial light modulator having a simple structure, high durability and a high response speed (claim 11). (12) In addition to the above, spatial distortion of an output signal is reduced. Providing a reduced spatial light modulator (Claim 1)
2), (13) In addition to the above, to provide a low-cost spatial light modulator (Claim 13), (14) To further provide a low-cost, small-sized spatial light modulator (Claim 14).
With the goal.

(15) Further, to provide an image display device having high durability and a large display capacity (claim 15), (16) In addition to the above, to provide a low-cost image display device ( (16), (17) To provide a small-sized image display device at a lower cost (Claim 1).
7) is the purpose.

[0012]

According to a first aspect of the present invention, there is provided a light guide member including a light incident surface, a light exit surface, and a total reflection surface having a portion capable of totally reflecting incident light; A reflection control member provided to face the total reflection surface of the light member and having a function of reducing the reflection intensity of the incident light in the total reflection direction, between the reflection control member and the light guide member. In an optical switching element comprising a variable refractive index material whose refractive index changes according to an external signal, the variable refractive index material is a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix. It is characterized by the following.

According to a second aspect of the present invention, in the first aspect of the present invention, the liquid crystal material of the variable refractive index material is a droplet having a particle size of 1/5 or less of the wavelength of incident light. It was done.

According to a third aspect of the present invention, in the first or second aspect of the invention, all the liquid crystal molecules of the liquid crystal material are arranged in one direction when no voltage is applied.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the reflection control member includes at least a light absorbing material.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the reflection control member includes at least a light scattering material.

According to a sixth aspect of the present invention, in any one of the first to third aspects, the reflection control member has at least a reflection surface fixed at an angle which is not parallel to the total reflection surface. It is what it was.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the angle formed by the incident light and the normal line of the total reflection surface when the incident light enters the variable refractive index material from the total reflection surface of the light guide member. When the the theta _2, the reflection control member intersects the reflective surface, the inclination angle with respect to forming substrate surface of the reflective control member is characterized by having a second surface is 90 ° - [theta] ₂ or less Things.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, a plurality of the reflection surfaces of the reflection control member are provided for a unit element for applying an external signal to the variable refractive index substance. It is characterized by having.

According to a ninth aspect of the present invention, in any one of the sixth to eighth aspects of the present invention, at least the reflection surface is covered between the reflection surface of the reflection control member and the variable refractive index material and the upper surface is formed. A layer substantially parallel to the total reflection surface of the light guide member is provided.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the light guide member includes a flat light guide having a surface serving as the total reflection surface, the incident surface, and the emission surface. Is characterized by being optically bonded to another light guide having the following.

An eleventh aspect of the present invention is characterized in that the optical switching elements according to any one of the first to tenth aspects are arranged in a two-dimensional array.

The invention of claim 12 is the invention of claim 11
Here, the refractive index of the light guide member is n ₁And the total reflection
Α is the interior angle between the surface and the exit surface, and the normal to the total reflection surface
And the angle between the output beam and the ON signal at
Tanα = {n₁ ^Twosin (α-θ) cos (α-θ)} / {1-n₁ ^Twosin^Two(α-θ)}.
It was done.

According to a thirteenth aspect of the present invention, the optical switching elements according to any one of the first to tenth aspects are arranged in a one-dimensional array.

According to a fourteenth aspect of the present invention, the optical switching element according to any one of the first to tenth aspects has a plane in which the optical switching elements are arranged in a one-dimensional array. It is characterized in that a driving mechanism for rotating and driving about one parallel axis is provided.

The invention of claim 15 is the invention of claim 11 or 1
2. A device comprising: the spatial light modulator according to 2; means for causing a light beam to enter the spatial light modulator; and means for projecting an image formed by the spatial light modulator onto a screen and displaying the image. It is.

According to a sixteenth aspect of the present invention, there is provided a spatial light modulator according to the thirteenth aspect, means for causing a light beam to be incident on the spatial light modulator, and a light beam emitted from the spatial light modulator. A scanning mechanism for scanning in a direction perpendicular to the arrangement direction of the optical switching elements, and means for projecting a light beam emitted from the scanning mechanism onto a screen for display.

According to a seventeenth aspect of the present invention, there is provided a spatial light modulator according to the fourteenth aspect, means for causing a light beam to enter the spatial light modulator, and an image formed by the spatial light modulator is projected and displayed on a screen. And means for performing the following.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A feature of the present invention is that a light guide includes a light incident surface, a light exit surface, and a surface having a portion capable of totally reflecting incident light (hereinafter, referred to as a total reflection surface). A reflection control member provided opposite the total reflection surface of the light guide member and having a function of reducing the reflection intensity of the incident light in the total reflection direction; and the reflection control member and the light guide. An optical switching element in which a refractive index variable substance whose refractive index is changed by an external signal is sandwiched between a member and a member, wherein the variable refractive index substance is a liquid crystal material in which a liquid crystal material is dispersed and held in a polymer matrix. An optical switching element characterized by being a molecular complex.

[0030] When the refractive index of the variable refractive index material is a refractive index n ₁ less than value n ₂ of the light guide member, the incident angle theta ₁ to the total reflection surface of the incident light _{sinθ 1 ≧ (n 2 / n} 1 When satisfying (1), the total reflection surface of the light guide member totally reflects the incident light so that almost 100% of the incident light is emitted from the emission surface. When an external signal is applied, the refractive index of the variable refractive index material changes (increases). When (1) is not satisfied, part or almost all of the incident light passes through the variable refractive index material and reaches the reflection control member. Therefore, the reflection intensity in the total reflection direction decreases. Further, even if the condition (1) is not satisfied at first, the refractive index of the refractive index variable substance changes (decreases) by the application of an external signal, and the same function is achieved even if the setting is satisfied. .

Since the variable-refractive-index substance is a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix, high-speed response can be achieved with a simple structure as described later. And found the present invention (claim 1).

As the liquid crystal / polymer composite, for example, a microcapsule in which a liquid crystal material is covered by a polymer film is bonded using a binder resin, or a mixture of a liquid crystal material and a polymer material (or a precursor thereof). There is a so-called polymer dispersed liquid crystal in which a liquid crystal material is phase-separated from a body. In any case, the structure is such that the liquid crystal droplets are dispersed in a polymer matrix, and it has been experimentally found that the response speed increases as the particle size of the liquid crystal droplets decreases. When the particle size is 1/5 or less of the wavelength, scattering is reduced and light transmittance is increased.
That is, it is preferable because light loss is significantly reduced (claim 2).

In the above-mentioned liquid crystal, it is preferable that all liquid crystal molecules are arranged in almost one direction when no voltage is applied. By making this direction substantially perpendicular to the direction in which liquid crystal molecules are aligned (electric field direction) when a voltage is applied, a large difference in refractive index can be obtained. Therefore, for the same incident angle, light entering the variable refractive index material when an external signal is applied is obtained. The transmittance can be increased, and a high S /
An N ratio can be obtained. Alternatively, an incident angle margin for obtaining the same S / N ratio is widened (claim 3).

It is preferable that the reflection control member contains at least a light-absorbing material from the viewpoint that the light-switching function is not affected even if the manufacture is easy or the incident angle changes. Specifically, pigments such as carbon black, iron oxide, and chromium oxide, layers composed of ultrafine metal particles or polymer films containing them, and polymer films colored with dyes such as direct black and acid black are used. What is necessary is just to form on a board | substrate. In addition, a plurality of pigments or dyes having different absorption wavelength ranges may be mixed to have absorption in a wide range of wavelength ranges, or the incident light wavelength range may be monochromatic light such as red, green or blue. Since it is only necessary to absorb only a specific wavelength range, a pigment or dye having absorption in a necessary wavelength range may be used. A light transmitting layer may be further formed on such a layer or film (claim 4).

As another reflection control member, one containing at least a light scattering material is preferable from the viewpoint of durability in addition to the above. In the case where the light-absorbing material is contained, particularly when the energy of the incident light is high, heat is generated by the absorbed energy, and the reflection control member or a portion in contact therewith may be deteriorated. If the material contains a light scattering material, the incident energy diverges, so that there is no deterioration or the like, and the durability is improved. Specifically, a layer made of white fine particles such as titanium oxide, aluminum oxide, and barium sulfate or a polymer film containing them may be formed on the substrate. A light-transmitting layer may be further formed on such a layer or film (claim 5).

As another reflection control member, it is preferable to have at least a reflection surface fixed at an angle which is not parallel to the total reflection surface from the viewpoint of further increasing the S / N ratio. In the case of a material containing the light absorbing material, since the light absorptance is not actually 100%, a component reflected on the back surface is slightly observed as leakage light. Further, in the case of a material containing a light scattering material, the reflection direction is basically random, so that the reflection component in the total reflection direction is also observed as leaked light.

If the reflecting surface is fixed at an angle that is not parallel to the total reflecting surface, the transmitted light is reflected by the reflecting surface in a direction other than the total reflecting direction. Can be reliably removed, and the S / N ratio can be increased. In this case, it is also possible to adopt a configuration in which the totally reflected light is set as an off signal and the reflected light in a direction other than the total reflection direction is set as an on signal. In such a configuration,
When the condition is not the total reflection condition, the transmittance of the incident light into the variable refractive index material does not become 100%. In other words, even if the reflection component in the total reflection direction is slightly contained, the light intensity at ON only slightly decreases. This has the advantage that the S / N ratio does not deteriorate. The above-mentioned reflection control member, specifically, after processing a metal or the like having a high reflectivity to have an inclined surface, or after processing a material having a low reflectivity such as glass, plastic, or ceramics to have an inclined surface. Alternatively, a high-reflectance metal film may be formed on the inclined surface, or such a structure may be formed on the substrate (claim 6).

In the above description, assuming that the angle between the incident light and the normal line of the total reflection surface of the light guide member when entering the variable refractive index material is θ ₂ , the reflection control member intersects the reflection surface, and the reflection control member intersects with the substrate surface. It is preferable to have another surface having an inclination angle of 90 ° -θ ₂ or less. By doing so, the distance from the bottom of the reflection surface to the total reflection surface of the light guide member can be reduced, so that the energy (drive energy) applied to the variable refractive index material can be reduced. ).

Further, it is preferable that a plurality of reflection surfaces of a reflection control member are provided for a unit element (for example, an arithmetic element, a pixel, etc.) for applying an external signal to the variable refractive index substance. By doing so, the distance from the bottom of the reflection surface region to the total reflection surface of the light guide member can be further reduced, so that the driving energy can be further reduced (claim 8).

When a layer (hereinafter, referred to as a flattening layer) covering at least the reflection surface and having an upper surface substantially parallel to the total reflection surface is provided between the reflection surface of the reflection control member and the variable refractive index material. Since the thickness of the variable refractive index material layer can be made substantially constant, and the thickness can be as thin as the wavelength of the incident light, the driving energy can be extremely reduced.
In this configuration, the reflection control member includes a flattening layer for convenience (claim 9).

In each of the above structures, the light guide member is obtained by optically joining a flat light guide having a surface to be a total reflection surface and another light guide having an entrance surface and an exit surface. Is preferred from the viewpoint of ease of production. In this case, after manufacturing a device including a flat plate light guide, a reflection control member, and a variable refractive index material sandwiched therebetween, the another light guide may be brought into optical contact with the light guide. Manufacturing is much easier than manufacturing a device using a light guide member having a complicated shape (claim 10).

By arranging the optical switching elements of the present invention one-dimensionally or two-dimensionally, a spatial light modulator can be formed. Such a spatial light modulator has a simple structure, high durability, and a high response speed. A one-dimensional spatial light modulator can perform two-dimensional spatial light modulation by using a scanning mechanism that scans in the direction perpendicular to the arrangement direction of the optical switching elements. Since it is cheaper than the spatial light modulator, the cost is low.
Further, by scanning the spatial light modulators arranged one-dimensionally by the scanning mechanism, a more compact and inexpensive spatial light modulator can be configured (claims 11, 13 and 14).

In the two-dimensionally arranged spatial light modulator, the refractive index of the light guide member is n ₁ , the internal angle between the total reflection surface and the emission surface is α, and the normal to the total reflection surface and the reflection in the ON signal. When the angle between the light and the output light is θ, tanα = {n ₁ ² sin (α-θ) cos (α-θ)} / {1-n ₁ ² sin ² (α-θ)}… It is preferable that (2) is set so that α is approximately satisfied. By doing so, it is possible to reduce the spatial distortion of the output signal.

By providing the above-mentioned spatial light modulator, a light beam incident means and a means for enlarging and projecting an image formed by the spatial light modulator on a screen, the display capacity is large,
A small and inexpensive image display device can be configured (claims 15, 16, and 17).

(Embodiment) FIG. 1 is a diagram for explaining a first embodiment of the present invention. The optically transparent light guide member 11 has an incident surface 12 on which light from a light source is incident,
It has a total reflection surface 13 for totally reflecting light rays, and an emission surface 14 for emitting totally reflected light rays to the outside of the light guide member 11. FIG. 1A is a diagram for explaining a state in which the above-described expression (1) is satisfied. The incident light is totally reflected by the total reflection surface 13 and is emitted from the emission surface 14. FIG. 1B is a view for explaining a state in which the refractive index of the refractive index variable substance 15 changes (increases) due to the application of an external signal (for example, a voltage) and does not satisfy Expression (1). Light does not undergo total reflection, and part or almost all reaches the reflection control member 16. The light that has reached the reflection control member 16 is not emitted in the total reflection direction because the absorption, scattering, or reflection direction is changed. Thereby, the light output from the emission surface 14 can be modulated.

The internal angle between the total reflection surface 13 and the entrance surface 12 is β, and the internal angle between the total reflection surface 13 and the exit surface 14 is α. The value of β is not particularly limited, but is preferably a value close to the incident angle θ ₁ from the viewpoint of reducing the reflection loss at the incident surface. α may be equal to or different from β. However, when the incident light incident from the incident surface 12 is totally reflected by the total reflection surface 13, the light guide member is not totally reflected by the emission surface 14. 11 must be satisfied. Further, it is desirable that the entrance surface 12 and the exit surface 14 are provided with an antireflection coat.

It is desirable that the light guide member 11 is made of glass, plastic, or crystal having a high transmittance with respect to incident light, and is made of an isotropic material having a small internal refractive index variation. Specific examples of the glass include flint glass, heavy flint glass, crown glass, heavy crown glass, light crown glass, borosilicate glass, quartz glass, and the like, and plastics such as polycarbonate, polymethyl acrylate, and polymethacrylic acid. Methyl and the like. A reflection control member 16 is provided so as to face the total reflection surface of the light guide member 11, and a variable refractive index substance 15 is held between the two.

The refractive index variable substance 15 of the present invention is a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix, and more specifically, a polymer in which a liquid crystal droplet 15a is dispersed in a polymer 15b. It is a dispersed liquid crystal. It is desirable that the thickness of this layer is such that the evanescent wave at the time of total reflection does not reach the reflection control member 16 at the thinnest portion, and at least １ ／ or more of the wavelength of the incident light.
Preferably, it is longer than the wavelength of the incident light. Hereinafter, the polymer dispersed liquid crystal will be described in more detail.

As the liquid crystal material, a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal, or the like can be used, and a single or two or more liquid crystal compounds or a mixture containing a substance other than the liquid crystal compound may be used. A transparent polymer is preferable as the polymer matrix material,
Any of a thermoplastic resin, a thermosetting resin, and a photocurable resin may be used. The method for producing a polymer-dispersed liquid crystal is described in (1)
Polymerization phase separation method in which a solution is formed from liquid crystal and a heat or photocurable (polymerizable) monomer, oligomer, or prepolymer, and phase separation is performed by polymerization. (2) A solution is formed from a liquid crystal, a polymer, and a solvent, and the solvent is evaporated. And (3) a thermal phase separation method in which a liquid crystal and a thermoplastic polymer are heated and dissolved, and then phase-separated by cooling.

As the polymer, it is preferable to use an ultraviolet-curable resin in view of easiness of the production process, separation from the liquid crystal phase, and the like. As a specific example, an ultraviolet curable acrylic resin is exemplified, and a resin containing an acrylic monomer or acrylic oligomer which is polymerized and cured by irradiation with ultraviolet light is particularly preferable. Examples of such a monomer or oligomer include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, melamine acrylate, and (poly) phosphazene methacrylate. As another example, a thiol-ene system can be suitably used because of its high photocuring speed.

A photopolymerization initiator may be used to carry out the polymerization promptly. Examples thereof include acetophenones such as dichloroacetophenone and trichloroacetophenone;
Hydroxycyclohexyl phenyl ketone, benzophenone, Michler's ketone, benzoyl, benzoin alkyl ether, benzyldimethyl ketal, monosulfide, thioxanthones, azo compounds, diallyliodonium salts, triallylsulfonium salts, bis (trichloromethyl) triazine compounds and the like. Can be.

A liquid material obtained by uniformly dissolving a liquid crystal material in the ultraviolet curable compound is applied to the reflection control member 16 and the light guide member 1.
After the injection, a UV-curable compound is cured by irradiation with UV light, and at the same time, the liquid crystal material is phase-separated to form a polymer-dispersed liquid crystal layer (variable refractive index substance 15). Usually, in this state, the liquid crystal droplet 15a
The orientation direction of the liquid crystal molecules 15c is different for each (see FIG. 1).
(A), however, by applying an electric field, all the liquid crystal molecules are almost aligned in the direction of the electric field (FIG. 1 (B)). Since the refractive index of the liquid crystal is different between the direction parallel to the molecular axis and the direction perpendicular to the molecular axis, the average refractive index of the entire layer differs between the state shown in FIG. 1A and the state shown in FIG. Occurs.

As a specific example of a polymer-dispersed liquid crystal, a nematic liquid crystal E7 (ordinary refractive index no = 1.522, extraordinary refractive index ne = 1.746) is dissolved in an ultraviolet curable prepolymer NOA60 (Norland). (Liquid crystal weight concentration 3
5%) and ultraviolet rays (400 mW / cm 2) (the average particle diameter of the liquid crystal droplet is about 60 nm) is used. In the case of FIG. Since the layer is random, the entire layer is an optically isotropic medium, and its refractive index is almost equal to the average refractive index of liquid crystal (≒ (2no + ne) /3≒1.6).
0) and the refractive index (≒ 1.56) of the polymer matrix can be regarded as the volume average (≒ 1.57). Note that, in this case, no orientation treatment was performed in advance. When the light guide member 11 is made of flint glass SF2 (nd = 1.648) and the incident angle θ1 is set to 75 °, the incident light is totally reflected since the formula (1) is satisfied. In the case of FIG. 1B, the liquid crystal molecules are arranged in the direction of the electric field. Assuming that the incident light is P-polarized light (linearly polarized light whose electric field vector is parallel to the plane of incidence), the refractive index of the liquid crystal with respect to P-polarized light is no · ne / (no ² sin ² θ ₁ + ne ² cos ^2).
Since θ ₁ ) ^1/2 = 1.723, the refractive index of the entire layer can be regarded as a volume average (≒ 1.62) of the refractive index of the polymer matrix (≒ 1.56). At this time, since the expression (1) is not satisfied, the incident light is not totally reflected and most of the light reaches the reflection control member 16.

The size of the liquid crystal droplet 15a in the polymer-dispersed liquid crystal can be changed by changing the composition of the prepolymer, the mixed concentration of the liquid crystal, the intensity of ultraviolet light at the time of curing, and the like. FIG. 2 is a diagram showing the relationship between the liquid crystal droplet size and the response speed. E7 and BL24 (Merck) and NOA60, 65 and 81 (Norland) were used as liquid crystal materials and prepolymers as appropriate. The response speed was measured by using the apparatus shown in FIG. 3 and measuring the total of the rise time (Ton) and the fall time (Toff) of the light output when a pulse voltage (200 V) was applied to the sample 24. In FIG. 3, 21 is a laser, 22 is a polarizer, 23 is a lens, 24 is a sample, 2
5 is an Au electrode, 26 is a polymer dispersed liquid crystal layer, 27 is a Si substrate, 28 is a lens, 29 is an analyzer, and 30 is a power meter. In Sample 24, the thickness of the polymer-dispersed liquid crystal layer 26 was 20 μm, and the optical path length was 1 mm. FIG. 4 schematically shows a state where an electric field is not applied to the polymer-dispersed liquid crystal layer 26 and a state where the electric field is applied. When no electric field is applied, as shown in FIG.
Since the direction of a is random, the refractive indices in the x-axis, y-axis, and z-axis directions are all equal, and the entire layer is an optically isotropic medium. When an electric field is applied in the z direction, FIG.
As shown in (2), since the molecular axes of the liquid crystal molecules are aligned in this direction, the refractive index in the z-axis direction increases, while the refractive indices in the x-axis and y-axis directions are equal to each other, and the size decreases. When light is incident from the x direction perpendicular to the direction of the electric field as shown in FIG. 3, birefringence occurs in the yz plane, so that the polarization state can be changed, and the light output through the analyzer changes. In the present invention, such a birefringence phenomenon is not used. However, since the behavior of liquid crystal molecules when an electric field is applied and a change in the refractive index associated therewith are used, the response speed shown in FIG. 2 can be similarly applied to the present invention. FIG. 2 shows that the response speed increases as the size of the liquid crystal droplet decreases.

Further, it is preferable from the viewpoint of light transmittance that the particle diameter of the liquid crystal droplet is set to 1/5 or less, more preferably 1/10 or less of the wavelength of the incident light. The result of calculating the light transmittance from the Rayleigh scattering theory is shown below. When a spherical scatterer having a volume V exists at a number density N, the light transmittance T of a medium having a thickness L is expressed by the following equation (3). T = ex
p (-NRL), R = 24π 3 ((m 2 -1) / (m 2 +2)) 2 V 2 / λ 4 ... (3) where, R represents the refraction of the scattering cross section, m is the scatterer The ratio of the index to the refractive index of the medium, λ, is the wavelength of the light used. m = 1.0
7. The transmittance T when L = 100 μm was calculated using the particle size d, volume fraction (= NV) and wavelength λ of the scatterer, ie, liquid crystal droplet, as parameters. As can be seen from the equation, T decreases as d increases (ie, V increases) and λ decreases. The transmittance is preferably 90% (T = 0.9) or more from the viewpoint of light use efficiency. FIG. 5 shows that the particle size at which T = 0.9 has a volume fraction of 10% (d (0.1)) and 30% (d
(0.3)) and 50% (d (0.5)). If the volume fraction is small, the amount of change in the refractive index is small and the S / N ratio cannot be obtained, so the volume fraction is preferably 10% or more, and 30 to 50%.
The degree is more preferred. At a volume fraction higher than this, fabrication becomes extremely difficult. From this viewpoint, as shown in FIG. 5, it is preferable that d is λ / 5 or less for a wavelength in the visible to infrared region applied as an optical switching element (d (0.
1)), it is more preferable that it is λ / 10 or less (d (0.5)). In this calculation, m and L are fixed. However, in an actual device, it is considered that the values are smaller than the above values.

FIG. 6 is a diagram for explaining a second embodiment of the present invention. When no voltage is applied (FIG. 6A)
The configuration is the same as that of the first embodiment except that all liquid crystal molecules in the droplet are arranged in substantially one direction. This arrangement direction is substantially perpendicular to the direction in which the liquid crystal molecules are aligned (the direction of the electric field) when a voltage is applied (in the case of FIG. 6B), and is horizontal to the total reflection surface 13 of the light guide member and perpendicular to the paper. Good to do. By doing so, a large refractive index difference can be obtained, so that the light transmittance into the variable refractive index material when an external signal is applied can be increased for the same incident angle, and a high S / N ratio can be obtained. be able to. Specifically, when a polymer-dispersed liquid crystal of the same material and formulation as in the first embodiment is used, and the incident light is P-polarized light, the polymer-dispersed liquid crystal layer (a refractive index variable substance) shown in FIG. The refractive index of (15) is the refractive index of the liquid crystal (= no · ne / (no ² cos ² θ ₁ + ne ² si)
n ² θ ₁ ) ^1/2 = 1.534) and the refractive index of the polymer matrix (≒ 1.56) can be regarded as the volume average (≒ 1.55). The light guide member 11 is made of a flint glass F2 (nd =
1.620) and setting the incident angle θ ₁ = 75 ° satisfies the expression (1), so that the incident light is totally reflected. In the case of FIG. 6B, the liquid crystal molecules are arranged in the direction of the electric field. When the incident light is P-polarized light, the refractive index of the liquid crystal with respect to P-polarized light is no · ne /
(No ² sin ² θ ₁ + ne ² cos ² θ ₁ ) ^1/2 = 1.723
Therefore, the refractive index of the entire layer can be regarded as a volume average (≒ 1.62) of the refractive index of the polymer matrix (≒ 1.56). At this time, since the expression (1) is not satisfied, the incident light is not totally reflected, and the refractive index of the light guide member and the refractive index of the layer of the refractive index variable substance 15 are almost equal, so that the interface reflection hardly occurs. , Reaches the reflection control member 16. This result is because the refractive index of the layer of the refractive index variable substance 15 when no voltage is applied (in the case of FIG. 6A) is smaller than that in the first embodiment, and therefore, for the same incident angle, the expression This is because the refractive index of the light guide member 11 for satisfying (1) can be set small. Conversely, when the light guide member 11 having the same material (refractive index) as that of the first embodiment is used, the angle of incidence can be made smaller (for example, θ ₁ = 72 °), so that there is a design margin. Increase. Further, also in this case, the interface reflection is reduced as compared with the first embodiment.

As a means for previously aligning the liquid crystal molecules in one direction, a method using an alignment film can be exemplified. As a method for forming an alignment film, a rubbing method in which the surface of an organic polymer film such as polyvinyl alcohol or polyimide is rubbed (rubbed) several times with a cotton cloth or a brush in a direction in which the long axis of liquid crystal molecules is to be aligned, Various existing methods can be used, such as an oblique evaporation method of obliquely evaporating an inorganic substance such as a method, a method of forming a grating by etching or the like. The alignment film is provided on the surface holding the variable refractive index material, that is, the outermost surface of the total reflection surface 13 of the light guide member 11 and the outermost surface of the reflection control member 16 (not shown).

As another means for arranging the liquid crystal molecules in one direction in advance, the following method can be used. By applying an electric field when polymerizing the polymer matrix material, the liquid crystal can be aligned in one direction. At this time, the prepolymer in contact with the liquid crystal is dragged by the alignment of the liquid crystal and is aligned in the same direction. When the prepolymer is polymerized in this state, the interface with the liquid crystal is fixed in a form following the orientation of the liquid crystal. Since this interface structure functions as an alignment film for the liquid crystal, even if the electric field is released after the polymer matrix material is cured, the liquid crystal is aligned in the direction of the electric field applied during polymerization.

FIG. 7 is a diagram for explaining a third embodiment of the present invention. FIG. 7A shows a state when no voltage is applied, and FIG. 7B shows a state when a voltage is applied. The refractive index variable substance 15 is a polymer dispersed liquid crystal,
The same one as in the first embodiment is used. Light guide member 11
Is flint glass SF2 (n ₁ = 1.645 at 63)
3 nm) and the incident light is P using a He-Ne laser light source.
The light is polarized and is incident on the total reflection surface 13 at an incident angle θ ₁ = 75 °. Reference numerals 31b and 31a denote transparent electrodes made of ITO, and the reflection control member 16 uses carbon black dispersed in an acrylic resin. Reference numeral 35 denotes a sealant made of an epoxy resin or the like. If you show an example of the manufacturing process,
An opening (injection hole) is left partially in the periphery of the light guide member (or the reflection control member) 11 with a thermosetting epoxy resin (beads or the like for maintaining a gap may be mixed if necessary). After printing, the reflection control member 16 (or the light guide member 11) is attached and cured by heating. A liquid material obtained by dissolving the liquid crystal material E7 in the prepolymer NOA 60 is injected through an injection hole, cured by irradiating ultraviolet rays, and completed by closing the hole with an adhesive.

As in the first embodiment, when no voltage is applied to the polymer-dispersed liquid crystal (at the time of FIG. 7A), the orientation of the liquid crystal droplet 15a is random, so that the refractive index of the entire layer is Almost the average refractive index of liquid crystal (≒ (2no + ne)
/3≒1.60) and the refractive index of the polymer matrix (≒ 1.5
6) and the volume average (≒ 1.57). In this case, since the expression (1) is satisfied, the incident light is totally reflected and exits from the exit surface 14. At this time, in order to prevent the evanescent wave leaking from reaching the reflection control member 16, it is preferable that the thickness of the polymer dispersed liquid crystal layer (refractive index variable substance 15) be about 0.6 μm or more. When a voltage is applied to the polymer-dispersed liquid crystal (in the case of FIG. 8B), the liquid crystal molecules are arranged in the direction of the electric field, and the refractive index of the liquid crystal with respect to P-polarized light is no · ne / (no ² sin ² θ ₁ + ne). ² cos ² θ ₁ )
^{Since 1/2} = 1.723, the refractive index of the entire layer is the volume average (≒ 1.6) of the refractive index of the polymer matrix (≒ 1.56).
2) can be considered. At this time, since the expression (1) is not satisfied, the incident light is not totally reflected, but mostly reaches the reflection control member 16 and is absorbed. In addition, the same function can be obtained by using a material in which titanium oxide fine particles are dispersed in an acrylic resin (light scattering material) as the reflection control member 16.

FIG. 8 is a diagram for explaining a fourth embodiment of the present invention. FIG. 8A shows a state in which no voltage is applied, and the liquid crystal molecules are aligned in one direction in advance as in the second embodiment. FIG. 8B shows a state when a voltage is applied. The reflection control member 16 is Si,
After forming an inclined surface on a substrate 34 made of glass or the like with an insulator 33 made of glass, plastic or ceramics such as silicon oxide, silicon nitride, aluminum oxide, or the like, the inclined surface is made of Al, Ag, or the like having a high reflectance. The reflection film 32 can be obtained by forming by a known method such as vacuum evaporation and sputtering. Moreover, you may pattern by photolitho etching as needed. This reflection film 32 also functions as an electrode. The reflection film 3 is formed on the substrate 34.
It is desirable to form a driving element or the like for applying a signal voltage to 2. As the reflection control member 16, a configuration in which the insulator 33 also serves as the substrate 34, a configuration in which an inclined surface is directly formed using a metal plate as a substrate, and the like are possible. As an example of a suitable inclined surface forming method, there is an anisotropic etching method in which patterning is performed using a photomask in which a pattern of area gradation or density gradation is formed and dry etching is performed. The light guide member 11 is made of a flint glass F2 (n ₁ = 1.617 a).
At t 633 nm), the incident light is converted into S-polarized light (linearly polarized light whose electric field vector is perpendicular to the plane of incidence) using a He-Ne laser light source, and is incident on the total reflection plane 13 at an incident angle θ ₁ = 75 °. . When no voltage is applied to the polymer-dispersed liquid crystal (FIG. 8A), the refractive index of the liquid crystal with respect to S-polarized light is ne.
= 1.746, the refractive index of the entire layer is the volume average (≒ 1.6) of the refractive index of the polymer matrix (≒ 1.56).
3) can be considered. In this case, since the expression (1) is not satisfied, the incident light is not totally reflected, and most of the light reaches the reflection control member 16 and the direction is changed by the reflection film 32. If an emission surface is provided in that direction, light is emitted. This emission surface may be the same as the surface from which the total reflected light is extracted (the emission surface 14), or may be separately provided as the second emission surface 36 as shown in FIG.

When a voltage is applied to the polymer dispersed liquid crystal (FIG. 8)
In (B)), the liquid crystal molecules are arranged in the direction of the electric field, and the refractive index of the liquid crystal with respect to S-polarized light is no = 1.522.
The refractive index of the entire layer is the refractive index of the polymer matrix (≒ 1.5
6) and (体積 1.55). At this time, since the expression (1) is satisfied, the incident light is totally reflected and exits from the exit surface 14. In this case, either of the cases shown in FIGS. 8A and 8B may be turned on.
By setting the ON signal at the time of (A), even if there is a reflected component (in the total reflection direction) at the interface of each layer, the light use efficiency is reduced, but the leakage light at the time of OFF is not generated.
/ N ratio can be increased.

FIG. 9 is a diagram for explaining a fifth embodiment of the present invention. When the incident light enters the variable refractive index substance 15, the angle between the incident light and the normal of the total reflection surface of the light guide member is θ _2.
Then, the reflection control member 16 has a surface (reverse inclined surface) 38 having one side common to the reflection surface 37 and having an inclination angle γ from the substrate surface of 90 ° −θ ₂ or less. Other configurations are the same as in the fourth embodiment. In this case, θ ₂ = sin
⁻¹ {(n ₁ / n ₂ ) sin θ ₁ } = 73 °, so γ
Is set to 17 ° or less, the light guide member 11 in FIG.
The irradiation area A of the incident light at the interface between the light guide member and the variable refractive index material 15 is the same as that of the fourth embodiment, so that the distance from the bottom of the reflection surface to the total reflection surface of the light guide member, that is, the refractive index variable material 15 The maximum thickness t _max of the layer can be reduced, and the driving voltage can be reduced.

FIG. 10 is a diagram for explaining a sixth embodiment of the present invention. In the region facing the irradiation area A in the fifth embodiment, the reflection surface 37 (and the reverse slope 3
8) are provided (two in FIG. 10). As is clear from FIG. 10, when A is equal to FIG. 9, t _max is further reduced, and the driving voltage can be further reduced.

FIG. 11 illustrates a seventh embodiment of the present invention.
FIG. Flat on the reflection control member 16
Layer 39 and a transparent electrode 31c are provided. flat
As the material used for the passivation layer 39, the incident light is a material having a variable refractive index.
After passing through the surface 15, the flattening layer 39 is further transmitted.
In other words, the refractive index variable substance 15 and the
Refractive index that does not cause total reflection at the interface with the carrier layer 39
Need to be used. Third embodiment and
Similarly, using flint glass SF2 for the light guide member 11,
When the incident light is P-polarized light, or as in the fourth embodiment,
(After pre-orientation is performed), flint gas is
Either when the incident light is converted into S-polarized light using the lath F2
May be used, in these cases, the refractive index of the planarizing layer and
The value of the higher refractive index of the variable refractive index material (in this example,
Is about 1.62).
Len and the like can be exemplified. The voltage is the transparent electrode 31b
And 31c. In the present embodiment, the light guide member
11 is P-polarized light using flint glass SF2
(Incident angle θ₁= 75 °). High
When no voltage is applied to the molecule-dispersed liquid crystal (FIG. 11A)
), The orientation of the liquid crystal droplet 15a is random.
Therefore, the refractive index of the entire layer is almost equal to the average refractive index of the liquid crystal (≒
(2no + ne) /3≒1.60) and polymer matrix
And the volume average (≒ 1.57) with the refractive index (≒ 1.56)
I can do it. In this case, since equation (1) is satisfied,
The incident light is totally reflected and exits from the exit surface 14. High polymer content
When a voltage is applied to the dispersed liquid crystal (in the case of FIG. 11B), the liquid
Crystal molecules are arranged in the direction of the electric field, and the refraction of the liquid crystal with respect to the P polarized light
The rate is no · ne / (no^Twosin^Twoθ₁+ Ne^Twocos
^Twoθ₁) ^1/2= 1.723, the refractive index of the entire layer is high
Volume average with the refractive index of the molecular matrix (分子 1.56)
($ 1.62). At this time, the expression
Since (1) is not satisfied, incident light is not totally reflected, and is mostly
Is transmitted through the refractive index variable substance 15 and the flattening layer 39,
The direction is changed by the reflection film 32 and the second exit surface 36
Exit from In this case, the refractive index variable substance (polymer dispersion
Drive) because the thickness of the thickest part of
The voltage can be reduced. In this configuration,
Therefore, the reflection control member 16 includes a flattening layer for convenience.
I do.

As a modification, the refractive index variable material 15
It is also possible to make total reflection at the interface between the layer and the flattening layer 39. In this case, as the flattening layer 39, a material which is closer to the lower value of the refractive index of the variable refractive index material (about 1.55 in this example) may be selected. What is necessary is just to select the light guide member which is closer to the higher value of the refractive index of the variable refractive index material (about 1.62 in this example).

FIG. 12 is a diagram for explaining the eighth embodiment of the present invention. The light guide member 11 optically joins a flat light guide 40 whose one surface is a total reflection surface and another light guide 41 having an entrance surface and an exit surface. Flat light guide 4
It is desirable that the refractive index of 0 and the light guide 41 be substantially equal. Other configurations are the same as those of the fifth embodiment, and the operation principle is also the same. Optical bonding is a state in which the gap between the two members is in close contact with each other so that it is sufficiently smaller than the wavelength of the light to be used. Specifically, a fluid object is interposed between the two members. Can be obtained by An object having fluidity may be solidified after ensuring close contact with both members. More specifically, it is preferable to use a low-volatile liquid or a photocurable adhesive having a refractive index substantially equal to that of the flat light guide and the light guide as the fluid object. In this embodiment, since the flat light guide 40 is in contact with the variable refractive index substance, the transparent electrode 31b is formed on the flat light guide 40. In this case, since the bonding of the light guide 41 may be performed last, the main part of the device can be manufactured without using a light guide member having a complicated shape, so that the yield is improved and the cost is reduced. Can be.

FIGS. 13 and 14 are views for explaining the ninth embodiment of the present invention. FIG. 13 is a diagram showing the one-dimensional spatial light modulator 50, FIG. 13 (A) is a perspective view thereof, FIG. 13 (B) is a front view of FIG. 13 (A) viewed from the direction A, and FIG. It is the side view seen from the B direction of FIG.13 (A). The basic configuration is the same as that of the fifth embodiment,
The reflection films 32 also serving as individual electrodes are arranged in a one-dimensional array. The substrate is preferably provided with a drive element connected to each individual electrode and for selectively supplying a signal thereto. By selectively applying a voltage signal to each individual electrode arranged in an array, only the reflected light from the selected individual electrode (reflection film) 32 is emitted from the emission surface 14 and ON / OFF of the linear light is performed. OFF (spatial light modulation) is possible. Two-dimensional spatial light modulation can be performed by combining with a scanning device that scans in a direction perpendicular to the direction in which the individual electrodes are arranged. Further, as shown in FIG. 14, the driving signal supply to the individual electrodes (reflection film) 32 of the spatial light modulator 50 and the driving of the scanning mechanism 54 composed of a galvanometer mirror and the like are controlled based on the image signal, and the two obtained. By projecting the three-dimensionally spatially modulated light beam on the screen 55 by the projection lens 53,
An image display device can be formed. In FIG. 14, a laser, an LED, a lamp, or the like can be used as the light source 51. Further, the collimator lens 52 may be an optical integrator, and a polarization conversion optical system (not shown) may be provided at the subsequent stage.

In FIG. 14, the light beam emitted from the light exit surface 14 of the spatial light modulator 50 is scanned and projected.
It is also possible to adopt a configuration in which the light emitted from the second emission surface 36 is scanned and projected.

FIG. 15 is a view for explaining the tenth embodiment of the present invention. In FIG. 15, a scanning mechanism 54 is provided in the one-dimensional spatial light modulator itself, and scanning is performed in a direction perpendicular to the direction in which the reflection films are arranged, thereby providing a more compact image display device. As the scanning mechanism, a galvano method using Lorentz force, a method using electrostatic force, a method using electrostriction or magnetostriction, or the like can be used. This mechanism can be integrally formed with an optical switching element (array) on a Si substrate using, for example, a micromachining technique. In the case of such a system in which two-dimensional scanning is performed by scanning the one-dimensional spatial light modulator, the incident angle of the light beam from the light source to the spatial light modulator changes according to the scanning. Even if the angle changes, if the total reflection condition expression (1) is satisfied, it functions as an optical switching element.

FIG. 16 is a view for explaining an eleventh embodiment of the present invention, and is a perspective view of a two-dimensional spatial light modulator 60. The basic configuration is the same as that of FIG. 15, but the reflection films 32 also serving as individual electrodes are arranged in a two-dimensional array. The substrate is preferably provided with a drive element connected to each individual electrode and for selectively supplying a signal thereto. By selectively applying a voltage signal to each individual electrode arranged in an array, only the reflected light from the selected individual electrode (reflection film) 32 exits from the exit surface 14 or the second exit surface 36, ON / OFF (spatial light modulation) of planar light can be performed. In this case, since the two-dimensional spatial light modulation can be performed only by the spatial light modulator, the scanning mechanism as shown in FIG. 14 is unnecessary, and a projection lens is provided outside the emission surface 14 or the second emission surface 36, and the screen is provided. An image display device can be formed by projecting the image.

In FIGS. 13 and 16, the light guide member 11 is commonly used as one, but the light guide member 11 may be divided for each optical switching element. Further, in an image display device using the one-dimensional array-like spatial light modulator or the two-dimensional array-like spatial light modulator, incident light of a plurality of wavelengths such as red, green, and blue is used, and each color is time-divided. A full-color image can be displayed by displaying an image (field sequential method) or by providing a plurality of spatial light modulators and simultaneously projecting images of each color.

In the two-dimensional spatial light modulator, particularly in an image display device using the same, as shown in FIG. 17, the image forming surface 47 on the total reflection surface is positioned with respect to the optical axis 46 of the projection optical system.
Is inclined, the screen projected by the projection optical system is inclined with respect to the optical axis, and the two-dimensional image modulated by the variable refractive index material becomes a distorted projected image 48 on the screen 45. In order to solve such a problem, the refractive index of the light guide member 11 is set to n1, and the total reflection surface 13 is set.
Is an internal angle between the light and the exit surface 14, and an angle between the normal to the total reflection surface 13 and the reflected light (output light) in the ON signal is θ.
Tanα = {n ₁ ² sin (α-θ) cos (α-θ)} / {1-n ₁ ² sin ² (α-θ)} ... (2) It is desirable to be set to. The reason will be described with reference to FIG.

As shown in FIG. 18, a light ray (output light ray) reflected on the total reflection surface 13 or passed through the total reflection surface 13 exits the air from the light exit surface 14 and reaches the refractive index n of the light guide member 11.
1 and the angle φ between the exit surface 14 and the light beam incident on the exit surface
Refraction according to 'When sin [phi' refraction angle after exit φ satisfies = n ₁ sinφ. When viewed from the refraction direction, due to the refraction effect, the total reflection surface 13 appears to have a distance of 1 / n _{1 in} the direction in which the refracted light ray is traced in the direction opposite to the traveling direction of the light ray. At this time, if the apparent total reflection surface (apparent image forming surface) 49 is substantially perpendicular to the emission direction,
That is, when the apparent total reflection surface is substantially perpendicular to the optical axis of the projection optical system, the projected screen can be provided substantially perpendicular to the optical axis.
Therefore, the apparent total reflection surface 49 can be projected on the screen substantially without distortion. In order to satisfy such a condition, the angle θ between the normal to the total reflection surface 13 and the light ray reflected from the total reflection surface 13 (output light beam) and the internal angle α between the total reflection surface 13 and the emission surface 14 It suffices that approximately satisfies Expression (2). The extent to which the deviation of the internal angle α between the total reflection surface 13 and the emission surface 14 is allowed depends on the refractive index n ₁ and θ of the light guide member 11, the use of the spatial light modulator, the system configuration, and the like. For example, when used in an image display device, a deviation of α is allowed within a range where distortion of a projected image cannot be recognized by human eyes.

As an example, in the case of the optical switching element shown in FIG. 7, n ₁ = 1.645 and θ = 75 °
Therefore, α satisfying the expression (2) is about 141 °. Also, in the optical switching element shown in FIG. 8, for example, when the inclination angle of the reflection control member 16 is set to 5 ° from the total reflection surface 13, the output light from the reflection control member 16 (FIG. 7A)
Is satisfied), since n ₁ = 1.617 and θ = 45 °, α satisfying the expression (2) is about 77 °. At this time,
The angle of refraction at the exit surface is about 49 ° with respect to the output light from the reflection control member 16, and the output light from the total reflection surface (FIG. 7).
(In the case of (B)) is about 3 °, and it is easy to separate them.

Further, an apparent total reflection surface (image forming surface) 4
9 is smaller than the actual total reflection surface 13 (image forming surface 47).
The depth does not change in the direction parallel to the optical axis of the incident light beam and perpendicular to the total reflection surface, but the following expression (4) applies to the direction parallel to both the optical axis of the incident light beam and the total reflection surface.
Are compressed by the magnification m shown in FIG. _{m = cosθ {1-n 1} 2 sin 2 (α-θ)} 1/2 / cos (α-θ) ... (4)

Therefore, the arrangement interval and the shape of the reflection control member 16 and the individual electrodes arranged two-dimensionally on the total reflection surface 13 are set in advance in consideration of the fact that the expression (4) is compressed in only one direction. A two-dimensional image having the designed shape can be obtained.

In the optical switching element shown in FIG. 8, when the angle θ = 0 °, that is, when the inclination angle of the reflection control member 16 is set so as to reflect the light in the direction perpendicular to the total reflection surface, α = 0 °. And m = 1 from the equation (4), so that it is not necessary to correct the magnification.

(Example) FIG. 19 is a view for explaining a method of manufacturing a two-dimensional spatial light modulator. The steps of manufacturing a reflection control member, manufacturing a cell, injecting, and curing are sequentially shown in FIG.
(A) to FIG. 19 (D). This will be described below in order. (A) Fabrication of Reflection Control Member A plurality of drive elements by MOSFET were formed on the surface of a Si substrate 34, and a 5 μm thick silicon oxide 33 was deposited thereon by CVD. Next, the inclined surface and the contact hole 56 were formed by patterning using a photomask on which an area gradation pattern was formed and performing dry etching. After filling the hole by metal CVD, aluminum was sputtered to a thickness of 0.1 μm.
It was deposited to a thickness and patterned so as to be a reflective film and individual electrode 32. On this is spin-coated 0.1 μm
An alignment film 58 was formed by forming a thick polyimide film and performing rubbing.

(B) Cell Preparation A transparent electrode 31d of 50 nm thick ITO and an alignment film 59 of polyimide are formed on the total reflection surface of the light guide member 11 made of flint glass (F2), and FIG.
The reflection control member of (A) was adhered using a sealing agent 35 made of an epoxy resin, thereby producing an empty cell. An injection hole was provided in a part of the sealant.

(C) Injection After evacuating the empty cell shown in FIG.
A mixture (liquid crystal concentration: 35 wt%) of 7) and an ultraviolet curable compound (NOA60) was injected, and the injection hole was sealed.

(D) Curing UV light (400 mW / cm ² ) was irradiated from a high-pressure mercury lamp to form a polymer-dispersed liquid crystal 15.

Using the spatial light modulator manufactured by the above-described steps, an image was displayed as follows. Laser light (wavelength 670 nm) shaped so as to have a substantially rectangular cross section is incident on the incident surface as S-polarized light, and the driving element 57 selectively allows individual electrodes 32 according to image data.
When a voltage (20 V) is applied to the second exit surface 35
, The spatially modulated output light was taken out, and an enlarged projection image could be obtained on a screen by a projection lens (not shown).

[0084]

According to the optical switching element of the first aspect, a variable refractive index material is provided between the total reflection surface and the reflection control member, and the variable refractive index material is a liquid crystal / polymer composite (polymer dispersed liquid crystal). ), It is possible to provide an optical switching element having a simple structure, high durability, and high response speed.

According to the optical switching element of the second aspect,
Since the variable-refractive-index substance is made of a polymer-dispersed liquid crystal, and the liquid crystal is a droplet having a particle diameter of 1/5 or less of the wavelength of the incident light, in addition to the above, it is possible to provide an optical switching element with small light loss. it can.

According to the optical switching element of the third aspect,
Since the variable-refractive-index substance is made of a polymer-dispersed liquid crystal and all liquid crystal molecules are arranged in one direction when no voltage is applied, in addition to the above, an optical switching element capable of increasing the S / N ratio is provided. can do.

According to the optical switching element of the fourth aspect,
Since the reflection control member includes at least the light absorbing material, in addition to the above, it is possible to provide an optical switching element having a simple structure and small incident angle dependence.

According to the optical switching element of claim 5,
Since the reflection control member includes at least the light scattering material, in addition to the above, it is possible to provide a more durable optical switching element.

According to the optical switching element of the sixth aspect,
Since the reflection control member has at least a reflection surface fixed at an angle that is not parallel to the total reflection surface, the S / N ratio is increased.
An optical switching element capable of increasing the ratio can be provided.

According to the optical switching element of the seventh aspect,
When the incident light is _two the angle between the normal of the total reflection surface θ when it enters the index variable material from the total reflection surface of the light guide member, the reflection control member from said reflecting surface and intersects the substrate surface Is provided with a second surface having an inclination angle of 90 ° -θ ₂ or less, so that an optical switching element capable of reducing driving energy can be provided.

According to the optical switching element of the eighth aspect,
Since a plurality of reflection surfaces of the reflection substrate are provided for a unit element for applying an external signal to the refractive index variable substance, it is possible to provide an optical switching element capable of further reducing driving energy.

According to the optical switching element of the ninth aspect,
To provide an optical switching element in which at least a layer covering at least the reflection surface and having an upper surface substantially parallel to the total reflection surface is provided between the reflection surface of the reflection control member and the refractive index variable substance, so that the driving energy can be further reduced. Can be.

According to the optical switching element of the tenth aspect, the light guide member is formed by optically joining a flat light guide having a surface to be a total reflection surface and another light guide having an entrance surface and an exit surface. Therefore, in addition to the above, it is possible to provide an optical switching element that is easy to manufacture.

According to the spatial light modulator of the eleventh aspect, since the optical switching elements of the first to tenth aspects are arranged in a two-dimensional array, a spatial light modulator having high durability and a high response speed is provided. be able to.

According to the spatial light modulator of the twelfth aspect, the angle of the internal angle between the total reflection surface and the light exit surface of the light guide member is defined by the relationship between the angle between the output light beam and the total reflection surface. In addition to the above, it is possible to provide a spatial light modulator with little spatial distortion of an output signal.

According to the spatial light modulator of the thirteenth aspect, since the optical switching elements of the first to tenth aspects are arranged in a one-dimensional array, in addition to the above, a spatial light modulator having a high manufacturing yield and a low cost can be provided. Can be provided.

According to the spatial light modulator of the fourteenth aspect, the optical switching element has a plane in which the optical switching elements are arranged in a one-dimensional array, and the plane is rotated about one axis parallel to the alignment direction of the optical switching elements. Since the driving mechanism for driving is provided, it is not necessary to separately provide a scanning device, and it is possible to provide a low-cost and small-sized spatial light modulator.

According to the image display device of the fifteenth aspect, the image formed by the spatial light modulator of the eleventh or twelfth aspect is projected on the screen, so that high-speed modulation is possible and the display capacity can be increased. An image display device having a long life can be provided.

According to the image display device of the sixteenth aspect, the light emitted from the spatial light modulator of the thirteenth aspect is scanned in the vertical direction and projected on the screen to obtain a two-dimensional image. A simple image display device can be provided.

According to the image display device of the seventeenth aspect, since the image formed by the spatial light modulator of the fourteenth aspect is projected on the screen, it is possible to provide a small-sized image display device at lower cost. it can.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a liquid crystal droplet size and a response speed.

FIG. 3 is a schematic configuration diagram of an apparatus for measuring a response speed of a polymer-dispersed liquid crystal.

FIG. 4 is a diagram schematically illustrating a state where an electric field is not applied to the polymer-dispersed liquid crystal layer and a state where an electric field is applied.

FIG. 5 is a graph showing the relationship between the particle size at which T = 0.9 and the volume fraction of 10%.
(D (0.1)), 30% (d (0.3)) and 50%
It is a figure which shows that it plotted with respect to wavelength about the case of (d (0.5)).

FIG. 6 is a diagram for explaining a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a third embodiment of the present invention.

FIG. 8 is a diagram for explaining a fourth embodiment of the present invention.

FIG. 9 is a diagram for explaining a fifth embodiment of the present invention.

FIG. 10 is a diagram for explaining a sixth embodiment of the present invention.

FIG. 11 is a diagram for explaining a seventh embodiment of the present invention.

FIG. 12 is a diagram for explaining an eighth embodiment of the present invention.

FIG. 13 is a diagram for explaining a ninth embodiment of the present invention.

FIG. 14 is another diagram for explaining the ninth embodiment of the present invention.

FIG. 15 is a diagram for explaining a tenth embodiment of the present invention.

FIG. 16 is a diagram for explaining an eleventh embodiment of the present invention.

FIG. 17 is a diagram for describing an image display device using a two-dimensional spatial light modulator.

FIG. 18 is a diagram for describing an image display device using the spatial light modulator according to the present invention.

FIG. 19 is a diagram illustrating a method for manufacturing a two-dimensional spatial light modulator.

FIG. 20 is a diagram illustrating an example of a conventional optical switching element.

FIG. 21 is a diagram illustrating the operation of a conventional optical switching element.

FIG. 22 is a diagram showing a schematic configuration of a conventional optical switching element.

[Explanation of symbols]

11: light guide member, 12: incident surface, 13, 49, 121 ...
Total reflection surface, 14, 36 ... emission surface, 15: variable refractive index material, 15a: liquid crystal droplet, 15b: polymer,
16: reflection control member, 21: laser, 22: polarizer, 2
3, 28 lens, 24 sample, 25 Au electrode, 26
... Polymer dispersed liquid crystal layer, 27 ... Si substrate, 29 ... Analyzer,
30 ... Power meter, 31a, 31b, 31c, 31
d, 102: transparent electrode, 32, 154: reflective film, 33:
Insulator, 34 ... substrate, 35 ... sealant, 37, 132 ...
Reflecting surface, 38: reverse inclined surface, 39: flattening layer, 40: flat light guide, 41, 150: light guide, 45, 55: screen, 46: optical axis, 47: image forming surface, 48: projection image,
50, 60: spatial light modulator, 51: light source, 52: collimating lens, 53: projection lens, 54: scanning mechanism, 56
... contact holes, 57 ... driving elements, 59 ... alignment films,
103: reflective electrode, 104a: state of transmitting incident light,
104b: a state of blocking incident light, 110, 111: light beam, 120: light guide, 130: prism, 131: extraction surface, 140: drive unit, 151: reflected light, 152: incident light (linearly polarized light), 153 ... total reflection light, 155 ... liquid crystal.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ikue Kawashima 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H079 AA02 AA12 BA01 CA02 CA21 DA08 EA13 EA28 GA04 GA05 HA12 HA15 KA05 2H088 EA37 GA10 HA14 HA21 HA23 KA05 KA09 LA06 MA10 2H089 HA04 SA02 TA01 TA13 TA17 TA20 UA03 2H091 FA16 FA21 FA23 FA34 FD07 JA02 KA01 MA07 2K002 AA07 AB10 BA06 CA14 DA02 EA14 EA25 GA07 GA10 HA02

Claims (17)

[Claims] 1. A light guide member including a light incident surface, a light exit surface, and a total reflection surface having a portion capable of totally reflecting incident light, and provided to face the total reflection surface of the light guide member. And a reflection control member having a function of reducing the reflection intensity of incident light in the total reflection direction, wherein a refractive index between the reflection control member and the light guide member is changed by an external signal. An optical switching element comprising a variable substance, wherein the variable refractive index substance is a liquid crystal / polymer composite in which a liquid crystal material is dispersed and held in a polymer matrix. 2. The liquid crystal material of the variable refractive index material,
2. The optical switching element according to claim 1, wherein the optical switching element is a droplet having a particle diameter of 1/5 or less of the wavelength of the incident light. 3. The liquid crystal material according to claim 1, wherein all of the liquid crystal molecules are aligned in one direction when no voltage is applied.
Or the optical switching element according to 2. 4. The optical switching element according to claim 1, wherein the reflection control member includes at least a light absorbing material. 5. The optical switching element according to claim 1, wherein the reflection control member includes at least a light scattering material. 6. The optical switching element according to claim 1, wherein the reflection control member has a reflection surface fixed at an angle that is not parallel to the total reflection surface. 7. When the incident light enters the variable-refractive-index material from the total reflection surface of the light guide member and forms an angle with the normal of the total reflection surface as θ ₂ , the reflection control member includes: optical switching element according to claim 6, wherein the intersecting the reflecting surface, the inclination angle with respect to forming substrate surface of the reflective control member and having a second surface is 90 ° - [theta] ₂ or less. 8. The reflection control member according to claim 6, wherein a plurality of the reflection surfaces of the reflection control member are provided for a unit element for applying an external signal to the variable refractive index substance. Optical switching element. 9. A layer is provided between the reflection surface of the reflection control member and the variable refractive index material, the layer covering at least the reflection surface and having an upper surface substantially parallel to the total reflection surface of the light guide member. 9. The method according to claim 6, wherein
3. The optical switching element according to claim 1. 10. The light guide member is formed by optically joining a flat light guide having a surface to be the total reflection surface and another light guide having the entrance surface and the exit surface. The optical switching element according to claim 1, wherein: 11. A spatial light modulator, wherein the optical switching elements according to claim 1 are arranged in a two-dimensional array. 12. The light guide member has a refractive index of n ₁ , an internal angle between the total reflection surface and the emission surface is α, and an angle between a normal line of the total reflection surface and an output light beam at the time of an ON signal. To θ
Tanα = {n ₁ ² sin (α-θ) cos (α-θ)} / {1-n ₁ ² sin ² (α-θ)} The spatial light modulator according to claim 11, wherein: 13. A spatial light modulator, wherein the optical switching elements according to claim 1 are arranged in a one-dimensional array. 14. An optical switching element according to claim 1, wherein the optical switching element has a plane arranged in a one-dimensional array, and the plane is centered on one axis parallel to the alignment direction of the optical switching element. A spatial light modulator, comprising a driving mechanism for rotationally driving the light. 15. A spatial light modulator according to claim 11 or 12, and means for causing a light beam to enter the spatial light modulator.
Means for projecting an image formed by the spatial light modulator onto a screen for display. 16. The spatial light modulator according to claim 13,
Means for injecting a light beam into the spatial light modulator, a scanning mechanism for scanning the light beam emitted from the spatial light modulator in a direction perpendicular to the alignment direction of the optical switching elements of the spatial light modulator, and the scanning Means for projecting light beams emitted from the mechanism onto a screen for display. 17. The spatial light modulator according to claim 14,
An image display apparatus comprising: means for causing a light beam to enter the spatial light modulator; and means for projecting and displaying an image formed by the spatial light modulator on a screen.