JP2002277761A - Light switching element, spatial light modulator and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light switching element which is operated at high speed with a high S/N rate, a simple structure and little reliance on an incident angle and also to provide a spatial light modulator and an image display device. SOLUTION: The spatial light modulator is provided with a light guide member 101 having a light incident surface 102, a light emitting surface 104 and a total reflection surface 103 providing a part to totally reflect the incident light generally in a light emitting surface direction, with a reflection control member 107 to be movable to respective positions, i.e., a first position being equal to or less than a distance for the leakage of evanescent wave concerning a position which is irradiated with the incident light on the total reflection surface 103 of the light guide member 101 and also the positions except the first position and with a driving part to drive the reflection control member 107. A work 112 for obstructing total reflection is performed at a partial or the whole part except a place opposing to the reflection control member 107 on the total reflection surface 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical switching device, a spatial light modulator, and an image display device.

[0002]

2. Description of the Related Art As an optical switching element, one using liquid crystal is known. FIG. 22 shows an example. ON / OF voltage between transparent electrode 202 and reflective electrode 203
By performing F, the state of transmitting the incident light 204a and the state of blocking the incident light 204b can be switched by controlling the orientation of the liquid crystal. This makes it possible to control the reflection of light.

[0003]

However, the response speed of a liquid crystal is about 100 μs even in the case of a ferroelectric liquid crystal which is said to be fast, and high-speed optical switching cannot be performed by an optical switching element using a liquid crystal. Further, when the incident angle changes, the transmission characteristics of the liquid crystal change, so that the intensity and wavelength of the reflected light change.

As another technique, for example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 11-202222. FIG. 23 is a diagram for explaining the operation of the optical switching element disclosed in JP-A-11-202222. Light guide 20 having total reflection surface 22 capable of transmitting light by total reflection
And a prism 34 capable of capturing the evanescent light by approaching the extraction surface 32 to the total reflection surface, reflecting the evanescent light and emitting the light, and a driving unit 40 for driving the optical switching unit in the light emission direction. On the other hand, the layers are stacked in this order.

[0005] The cell on the right side of FIG. 23 shows a state in which the prism 34 is located at a position separated by more than the extraction distance at which the evanescent light leaks by operating the driving unit 40. At this time, the light rays 10 propagating through the light guide 20
23 is totally reflected by the total reflection surface 22 as shown in FIG. 23, and exits rightward in the figure. When the driving unit 40 is not operated, the prism 34 is close to the extraction distance at which the evanescent light leaks, as in the cell on the left side of FIG. As shown in the cell, the light enters the prism 34 without being reflected by the total reflection surface 22. The light beam that has entered the prism 34 is reflected by the reflecting surface 34a of the prism, and is transmitted through the light guide unit 20 and emitted as the light beam 12 shown in FIG.

In this system, 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 can be expected at a low driving voltage. However, generally, incident light is a light beam having a certain width, and a portion where the extraction surface 32 of the total reflection surface 22 faces the extraction surface 32. Therefore, when observed in the total reflection direction (right direction in the figure), there is a problem that even when the drive unit 40 is not operating, some light beams are emitted, and the S / N ratio is reduced.

Further, in the above configuration, when the driving section 40 is not driven, the light beam passes through the light guide section 20 and is emitted upward, so that it is in an off state when observed in the total reflection direction (right direction in the figure). . When such an optical switching element is used for a spatial light modulator, for example, the operation of each switching element is such that light is emitted in the observation direction (that is, the on state) in many cases longer than the off state, so that it is not driven. Sometimes o
In the ff state, the number of times of driving increases, so that the load on the driving unit increases, and there is a problem that the life is shortened.

A prism 34 as shown in FIG.
Is complicated, it is difficult to uniformly form a plurality of them in a minute size on a substrate, and therefore, there is a problem that the manufacturing yield is reduced and the cost is increased.

FIG. 24 shows an example of a projection apparatus using this optical switching element. When the drive unit operates, the light beam emitted in the total reflection direction is reflected by the reflection surface 82 in FIG. 24 and returns to the optical switching element again (at this time, the non-projection = off state). When the drive unit is not operated, light rays emitted in a direction substantially perpendicular to the total reflection surface enter the projection lens 85 and are projected on a screen or the like (not shown).

In such a projection apparatus, the angle of incidence of incident light on the light guide section 20 must be kept constant in order to project the light with the projection lens 85. Therefore, the system can be freely configured. However, there has been a problem that the degree of reduction is reduced and miniaturization of the apparatus becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an S / N ratio, a simple structure, a small incident angle dependence, and a high-speed operation of an optical switching element, a spatial light modulator, And an image display device using the same. It is another object of the present invention to provide an optical switching element, a spatial light modulator which has a long life, has a simple structure, operates at high speed with little dependence on the incident angle, and an image display device using the same.

[0012]

In order to solve the above-mentioned problems, an optical switching element according to the first aspect of the present invention includes a light incident surface, a light exit surface, and total reflection of incident light in a direction substantially corresponding to a light exit surface. Surface with a part that can be
A light guide member having a total reflection surface), a first position that is equal to or less than a distance at which an evanescent wave leaks from a position where the incident light of the total reflection surface of the light guide member is irradiated, A reflection control member movable to a position and a drive unit for driving the reflection control member, and a part or all of the total reflection surface other than the part where the reflection control member faces is subjected to a process of inhibiting total reflection. It is characterized by having.

The optical switching element according to a second aspect of the present invention is characterized in that, in the first aspect of the present invention, the processing for inhibiting the total reflection is a processing for providing a light absorbing ability.

The optical switching element according to a third aspect of the present invention is characterized in that, in the first aspect of the invention, the processing for inhibiting the total reflection is a processing for imparting light scattering ability.

According to a fourth aspect of the present invention, in the optical switching element according to the first aspect, the step of inhibiting the total reflection is a step of imparting light transmittance, and the step of guiding the incident light to the light guide. The process is characterized in that the process enables light to be guided in a direction other than the direction of the member.

The optical switching element according to a fifth aspect of the present invention provides a light switching element having a surface having a light incident surface, a light exit surface, and a portion capable of totally reflecting incident light in a substantially exit direction. A light guide member having a first position that is less than or equal to a distance at which an evanescent wave leaks from a position where incident light is applied to the total reflection surface of the light guide member, and a position other than the first position. A possible reflection control member and a driving unit for driving the reflection control member, wherein the reflection control member is located at a position other than the first position which is equal to or less than a distance at which an evanescent wave leaks when a drive signal is not applied. I do.

According to a sixth aspect of the present invention, in the optical switching element according to any one of the first to fifth aspects, the reflection control member includes at least a light absorbing material.

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

According to an eighth aspect of the present invention, in the optical switching element according to any one of the first to fifth aspects, the reflection control member is made of a light transmissive material, and the incident light is guided by the light guide. Light is guided in a direction other than the direction of the member.

Further, the spatial light modulator according to claim 9 is:
The optical switching elements according to any one of claims 1 to 8 are arranged in a two-dimensional array.

A spatial light modulator according to a tenth aspect is characterized in that the optical switching elements according to any one of the first to eighth aspects are arranged in a one-dimensional array.

A spatial light modulator according to claim 11 has a plane in which the optical switching elements according to any one of claims 1 to 8 are arranged in a one-dimensional array. A drive mechanism is provided for driving to rotate about one axis parallel to the alignment direction of the optical switching elements.

According to a twelfth aspect of the present invention, there is provided an image display device, wherein the spatial light modulator according to the ninth aspect, means for causing a light beam to enter the spatial light modulator, and an image formed by the spatial light modulator Means for projecting and displaying the image on a screen.

According to a thirteenth aspect of the present invention, there is provided an image display device, wherein the spatial light modulator according to the tenth aspect, means for causing a light beam to enter the spatial light modulator, and a light beam emitted from the spatial light modulator A scanning mechanism that scans in a direction perpendicular to the alignment direction of the optical switching elements of the spatial light modulator,
Means for projecting a light beam emitted from the scanning mechanism onto a screen for display.

According to a fourteenth aspect of the present invention, there is provided an image display device, wherein the spatial light modulator according to the eleventh aspect, means for causing a light beam to enter the spatial light modulator, and an image formed by the spatial light modulator Means for projecting and displaying on a screen,
It is characterized by having.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical switching element, a spatial light modulator and an image display device according to the present invention will be described below in detail with reference to the accompanying drawings.

The optical switching element according to the present invention includes a light incident surface, a light outgoing surface, and a surface having a portion capable of totally reflecting incident light in the direction of the outgoing surface (hereinafter, referred to as a total reflection surface). A light guide member provided, a reflection control that can be moved to a first position which is equal to or less than a distance at which an evanescent wave leaks, and a position where the incident light of the total reflection surface of the light guide member is irradiated, and other positions. A member and a driving unit for driving the member are provided, and a part or all of the part of the total reflection surface other than the part where the reflection control member faces is subjected to processing for inhibiting total reflection.

When the reflection control member is not at the first position, 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. At this time, the refractive index of the light guide member is n ₁ and the outside of the light guide member (generally air)
Is assumed to be n ₀ , in order for the incident light to be totally reflected by the total reflection surface, the incident angle γ to the total reflection surface, which is the angle formed by the normal to the total reflection surface, is sin γ> n ₀ / n ₁ (Equation 1)

When the reflection control member moves to the first position which is shorter than the distance at which the evanescent wave leaks from the total reflection surface, the reflection control member absorbs or scatters the evanescent wave permeated from the total reflection surface or moves in a direction other than the light guide member. By guiding, the total reflection surface is brought into a non-total reflection state. Here, by performing a process of inhibiting total reflection on a part or all of the total reflection surface other than the portion where the reflection control member faces, leakage light when the reflection control member is at the first position is reduced. Since the cutoff can be performed, the S / N ratio can be increased. This operation mechanism will be described with reference to FIGS.

FIG. 1 shows a case where no special processing is applied to the total reflection surface 103, (a) when the reflection control member is not at the first position, and (b) when the reflection control member is moved to the first position. is there.
In (a), the incident light 108 is totally reflected and converted to almost 100% outgoing light 110. In (b), most of the incident light does not reach the emission surface 104 due to the operation of the reflection control member, but the light beam irradiated to a portion where the reflection control member does not face is totally reflected and emitted as the leak light 111. The S / N ratio when observed from the surface decreases.

FIG. 2 shows a case where a process 112 for inhibiting total reflection is performed on a portion of the total reflection surface 103 where the reflection control member does not face, and FIG. 2A shows a case where the reflection control member is not at the first position.
(B) is when it has moved to the first position. In (a), of the incident light 108, the light beam applied to the opposite surface of the reflection control member is totally reflected and converted to almost 100% outgoing light 110. In (b), the light is cut off by the action of processing that inhibits total reflection, and almost 100% of the incident light disappears without reaching the emission surface 104. In FIG.
Since the light amount of 0 is slightly smaller than the light amount of the incident light 108, the light use efficiency is slightly reduced. However, since there is almost no leakage light in (b), the S / N ratio when observed from the exit surface is low. Get higher.

The above-mentioned processing for inhibiting total reflection is preferably processing for imparting a light absorbing ability from the viewpoint of ease of production. 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. A pattern may be formed by photolithography or the like on a portion of the total reflection surface where the reflection control member does not face. 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.

As another process for inhibiting total reflection, a process for imparting light scattering ability is preferable from the viewpoint of durability. In the case of the processing for providing the light absorbing ability, particularly when the energy of the incident light is high, heat is generated by the absorbed energy, and the processed part may be deteriorated. In the case of processing for imparting light scattering capability, the incident energy is diverged, so that no alteration or the like occurs, 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 by patterning with photolithography or the like on a portion of the total reflection surface where the reflection control member does not face. .

As still another processing for inhibiting total reflection,
From the viewpoint of further increasing the S / N ratio, it is preferable that the process for imparting light transmittance is a process for allowing incident light to be guided in a direction other than the direction of the light guide member. In the case of the processing for imparting the light absorptivity, since the light absorptance is not actually 100%, a component reflected on the processed surface is slightly observed as leakage light. In addition, in the case of processing for imparting light scattering capability, the reflection direction is basically random, so that the reflection component in the total reflection direction is also observed as leakage light. If it is processing that imparts light transmission capability and processing that allows incident light to be guided in a direction other than the direction of the light guide member, the reflected component in the total reflection direction can be reliably removed. , S / N ratio can be increased.

Specifically, a light-transmitting material such as glass or plastic is formed into a triangular prism shape, or a thin film material having an appropriate refractive index is provided with a waveguide structure in which incident light propagates while repeating total reflection at the film interface. It may be formed at a position on the total reflection surface where the reflection control member does not face by designing and stacking.

The light guide member to be subjected to these processes may be a so-called prism in which the entrance surface and the exit surface are inclined with respect to the total reflection surface, but may be optically connected to the prism 113 as shown in FIG. Alternatively, the flat plate 114 may be provided. In this case, after the flat plate is processed (further, after the flat plate is integrated with the base member on which the reflection control member and the drive unit are formed), the flat plate can be joined to the prism, which has an advantage that manufacturing is easy. is there.

It is preferable that the reflection control member contains at least a light-absorbing material, since the ease of manufacture and the change in the incident angle do not affect the optical switching function. 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 a pattern on a drive part with photolithography etc.

Further, a plurality of pigments or dyes having different absorption wavelength ranges may be mixed to have absorption in a wide range of wavelength ranges, and the incident light wavelength range may be monochromatic such as red, green or blue. In the case of light, it is only necessary to absorb light in a specific wavelength range, so that a pigment or dye having absorption in a required wavelength range may be used. A light-transmitting layer may be further formed on such a layer or film.

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 driving section by photolithography or the like. A light-transmitting layer may be further formed on such a layer or film.

As another reflection control member, a member made of a light-transmitting material and guiding incident light in a direction other than the direction of the light guide member is preferable from the viewpoint of further increasing the S / N ratio. preferable. 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. Also,
In the case of a material containing a light scattering material, the reflection direction is basically random, so that a reflection component in the total reflection direction is also observed as leaked light.

A light transmitting material that guides incident light in a direction other than the direction of the light guide member can surely remove the reflected component in the total reflection direction. Can be higher. Specifically, a light-transmitting material such as glass or plastic is formed into a triangular prism shape, or a thin film material having an appropriate refractive index is formed into a waveguide structure in which incident light propagates while repeating total reflection at the film interface. What is necessary is just to provide on a drive part by designing and laminating.

By arranging the optical switching elements of the present invention one-dimensionally or two-dimensionally, a spatial light modulator can be formed. The one-dimensionally arranged 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. By scanning with the scanning mechanism, a small and inexpensive spatial light modulator can be configured.

Hereinafter, the operation mechanism of the optical switching element according to the present invention will be described in more detail. One embodiment of the present invention is shown in FIG. The optically transparent light guide member 101 includes an incident surface 102 on which a light beam from a light source is incident, a total reflection surface 103 that totally reflects the light beam, and an emission surface 104 that emits the totally reflected light beam to the outside of the light guide member 101. Have. An internal angle between the total reflection surface 103 and the incident surface 102 is α, and an internal angle between the total reflection surface 103 and the output surface 104 is β.

At least the total reflection surface 103 and the incident surface 102
Is greater than 0 ° and 90 ° or less. The angle β formed by the total reflection surface 103 and the light exit surface 104 may be equal to or different from the angle α formed by the total reflection surface 103 and the light incident surface 102. When the light guide member 108 is totally reflected by the total reflection surface 103 without being totally reflected by the emission surface 104,
01 must be satisfied. This condition includes an angle α between the incident surface 102 and the total reflection surface 103,
The angle at which the incident light 108 enters the light guide member 101,
It depends on the refractive index of the light guide member and the surrounding space. Also,
It is desirable that the entrance surface 102 and the exit surface 104 are provided with an anti-reflection coating.

The light guide member is made of glass, plastic, or crystal having high transmittance for incident light. It is desirable to use an isotropic material having a small variation in the internal refractive index. Specifically, as glass, flint glass, heavy flint glass, crown glass, heavy crown glass, light crown glass,
Boron crown glass, quartz glass and the like can be mentioned, and as plastics, polycarbonate, polymethyl acrylate, polymethyl methacrylate and the like can be mentioned. As a manufacturing method, a general method such as a molding method using a mold or a shaping method using polishing can be used. On the side of the total reflection surface of the light guide member 101, a reflection control member 107 that can come and go is provided.

The reflection control member is as described above. The reflection control member is moved to a first position equal to or less than the distance at which the evanescent wave leaks by approaching the total reflection surface 103 of the light guide member 101 by a driving unit (not shown), and is separated from the total reflection surface 103. , Can be moved to a position other than the first position which is equal to or shorter than the distance at which the evanescent wave leaks. In the portion of the total reflection surface 103 where the reflection control member does not face, the above-described processing 112 for inhibiting total reflection is performed so as to block off leakage light (during dark).

The incident light 108 is emitted from a light source (not shown), is shaped into a required shape by an optical system (not shown), and then enters the light guide member 101 from the incident surface 102. When the reflection control member 107 is separated, the incident light 108 is totally reflected by the total reflection surface 103 as shown in FIG.
At this time, since equation 1 must be satisfied, as shown in FIG. 4A, the angle between the light beam incident on the incident surface 102 and the normal to the total reflection surface 103 is defined as an incident angle θ.

(Equation 1) Must.

FIG. 4B is a graph of Equation 2 when the refractive index of the light guide member 101 is 1.5. This is a condition under which the hatched area is totally reflected by the total reflection surface 103. When the incident angle θ is larger than 0 ° and equal to or smaller than 90 °, the incident surface 1
02 and the total reflection surface 103, the smaller the minimum value of the incident angle θ of the incident light becomes, the wider the incident angle range for total reflection can be set.

However, if the angle α between the incident surface 102 and the total reflection surface 103 exceeds 90 °, the incident surface 102 faces downward, and if θ> α−90 °, the light cannot enter the incident surface. Can not. As a result, as the angle α between the incident surface and the total reflection surface increases, the minimum value of the incident angle θ increases, and the incident angle range in which the total reflection on the total reflection surface 103 can be narrowed. From the above, for the purpose of the present invention, it is particularly desirable that the angle α formed between the incident surface and the total reflection surface be greater than 0 ° and 90 ° or less.

Although a drive mechanism for driving the reflection control member 107 is not shown, various existing methods such as a method using electrostatic force, a method using magnetism, a method using electrostriction or magnetostriction can be used. For example, FIGS. 9 to 11 show a manufacturing method of an example of a method using electrostatic force. Silicon substrate 150
A silicon oxide layer 151 is formed on the surface by thermal oxidation or the like, and a silicon nitride layer 152 is formed thereon by a CVD method. Further, a conductive layer 153 of a high melting point metal such as tungsten is formed by sputtering or vapor deposition, and a sacrificial layer 154 of phosphorus silicate glass, boron phosphorus silicate glass, or the like is formed by CVD.

Next, patterning and etching with a photoresist material are performed to obtain the shape shown in FIG. Further, as shown in FIG. 10, silicon nitride or the like is formed as the elastic material layer 155 by a CVD method, and an electrode layer 158 made of a metal is formed thereon by sputtering or vapor deposition. Next, a reflection control member layer 156 is formed. As a forming method, sputtering, vapor deposition, coating, and other existing methods can be used. The reflection control member and the reflection control member driving mechanism are completed by etching the sacrificial layer as shown in FIG.

The light guide member and the substrate having the reflection control member and the reflection control member drive mechanism manufactured as described above are
As shown in FIG. 12, an optical switching element or a spatial light modulator can be formed by bonding together via a gap control material or the like (not shown).

As another method of the driving mechanism for driving the reflection control member 107, for example, FIGS. 15 to 17 show a manufacturing method of an example of a method using an electrostatic force. Silicon substrate 15
0, a silicon oxide layer 151 is formed on the surface by thermal oxidation or the like,
After performing groove processing by photolithographic etching, a conductive layer 153 of a refractory metal such as tungsten is formed by sputtering or vapor deposition, and a separation layer 154 of phosphorus silicate glass or boron phosphorus silicate glass is formed by a CVD method. Next, patterning and etching by photolithography are performed to obtain the shape shown in FIG. Further, as shown in FIG. 16, silicon nitride or the like is formed by CVD as the elastic material layer 155.
Then, an electrode layer 158 made of metal is formed thereon by sputtering or vapor deposition. Next, a reflection control member layer 156 is formed. The formation method is sputtering, evaporation,
Coating or other existing methods can be used. The reflection control member and the reflection control member driving mechanism are completed by etching the separation layer as shown in FIG. As shown in FIG. 18, the substrate having the reflection control member and the reflection control member driving mechanism and the light guide member are bonded together via a gap control material or the like (not shown) as shown in FIG. Or a spatial light modulator. When a voltage having the same sign is applied to the conductive layer 153 and the electrode layer 158, an electrostatic repulsion acts to bring the reflection control member closer to the light guide member as shown in FIG. FIG. 20 shows another example of the reflection control member and the reflection control member driving mechanism. Conductive layer 15 on the surface of silicon substrate 150
A material layer similar to that of FIG. On the other hand, the transparent conductive layer 15 having a large refractive index, such as ITO, is formed on the total reflection surface of the light guide member by sputtering or vapor deposition.
Then, patterning and etching by photolithography are performed. By applying voltages of opposite signs to the transparent conductive layer 159 and the electrode layer 158, an electrostatic attractive force acts to bring the reflection control member closer to the light guide member as shown in FIG.

FIG. 5 shows another embodiment of the present invention. FIG.
By arranging the reflection control members 107 in a one-dimensional array as shown in (a), a one-dimensional spatial light modulator 120 can be formed. 5 (b) and 5 (c) respectively show FIG.
FIG. 3A is a diagram viewed from a direction A and a direction B. When each reflection control member 107 arranged in an array approaches or separates from the total reflection surface 103, 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 reflection control members are arranged. Further, as shown in FIG. 6, the driving of the reflection control member 107 of the spatial light modulator 120 and the driving of the scanning device are controlled based on the image signal, and the obtained two-dimensional spatial light modulated light beam is projected on the screen 125. By doing so, an image display device can be formed. Furthermore, as shown in FIG. 7, a scanning mechanism 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 control members are arranged, so that a more compact image display device can be provided. . 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 (Equation 1) is satisfied, it functions as an optical switching element.

In FIG. 5, FIG. 6, and FIG. 7, the one-dimensional array of light guide members is commonly used as one light guide member. However, the light guide member may be divided for each optical switching element. As the scanning mechanism, an existing method such as a galvano method using Lorentz force, a method using electrostatic force, a method using electrostriction or magnetostriction can be used.

By arranging the reflection control members in a two-dimensional array as shown in FIG. 8, a two-dimensional spatial light modulator can be formed. In this case, since two-dimensional spatial light modulation can be performed only by the spatial light modulator, an image display device can be formed without providing a scanning mechanism as shown in FIGS. In FIG. 8, one light guide member is used in common, but the light guide member may be divided for each optical switching element.

In an image display device using the one-dimensional array spatial light modulator or the two-dimensional array spatial light modulator, incident light of a plurality of wavelengths such as red, green, and blue is used, and each color is time-divisionally divided. (Field sequential system), or by providing a plurality of spatial light modulators and simultaneously projecting images of each color, a full-color image can be displayed.

(Embodiment 1) As a light guide member, quartz glass is polished to form an equilateral triangle having a cross section of 5 mm and a length of 1 mm.
A 0 mm regular triangular prism was produced. The surfaces including the sides of the equilateral triangle are the incident surface, the total reflection surface, and the emission surface, respectively, and the portion of the total reflection surface where the reflection control member does not face is subjected to processing for inhibiting total reflection. Here, a carbon black layer was formed by sputtering in order to impart light absorbing ability.

Next, a reflection control member and its driving mechanism were manufactured as follows. As shown in FIG. 9, first, a silicon oxide layer 151 is formed on the surface of a silicon substrate 150 by heat treatment.
Was formed thereon, and a silicon nitride layer 152 was formed thereon by a low pressure CVD method. Further, the conductive layer 153 is formed by vapor deposition.
Was formed. The conductive layer material is tungsten or molybdenum,
A high-conductivity metal or alloy having high conductivity such as tantalum is desirable, and tungsten is used here.

Further, a sacrificial layer 1 is further formed thereon by the CVD method.
54 were formed. The sacrificial layer forms a movable space,
This is a layer to be selectively etched in a later step. As a material of the sacrificial layer, an impurity-added glass such as phosphorus silicate glass or boron phosphorus silicate glass is usually used. Here, phosphorus silicate glass is used. The thickness of the sacrificial layer may be more than the distance that the evanescent wave leaks from the total reflection surface of the light guide member integrated in the later step when the reflection control member layer manufactured in the later step is driven. What can form a movable space is required. Here, the thickness of the sacrificial layer was set to 0.6 μm. Next, by patterning and etching with a photoresist material, a concave portion for forming a column portion of the doubly supported beam was formed such that the length L of the doubly supported beam was 200 μm. In addition,
The length D in FIG. 9 in the depth direction is 5 mm.

Further, as shown in FIG. 10, an elastic material layer 155 constituting a doubly supported beam is formed. The elastic material layer has a role of a spring that bends downward due to electrostatic force and quickly returns upward when the electrostatic force is released. The elastic material used for the elastic material layer preferably has such a spring force. Here, the elastic material is formed by CVD using silicon nitride. The electrode layer 158 is formed on the upper surface of the elastic material layer. Here, it was formed by an evaporation method using aluminum. Next, a reflection control member layer 156 is formed. As described above, the reflection control member brings the total reflection surface of the light guide member into a non-total reflection state by absorbing or scattering light rays or guiding the light guide member in a direction other than the direction of the light guide member. Here, a carbon black layer was formed by sputtering.

Next, as shown in FIG. 14, patterning and etching are performed with a photoresist so that the width W of the doubly supported beam is 80 μm and the interval g between each doubly supported beam is 4 μm, and separation and sacrifice between the doubly supported beams are performed. The layer 154 was removed. The conductive layer 153 is used as a common electrode, and an electrode is extracted from the electrode layer of each doubly supported beam. Finally, a one-dimensional spatial light modulator was manufactured in combination with a quartz prism as a light guide member. In the state in which no signal is input to the electrode, the spatial light modulator thus manufactured exhibits a non-total reflection state because the reflection control member layer is in contact with the total reflection surface of the light guide member as shown in FIG.
When a voltage is applied between the conductive layer and the electrode layer of the selected doubly supported beam, the doubly supported beam is deformed as shown in FIG. 13 so that the reflection control member layer is separated from the total reflection surface and the total reflection surface is totally reflected. State.

In this embodiment, the beam shape is 1 mm × 5
mm laser (wavelength 670)
nm) from the entrance surface of the quartz prism, and selectively driving the drive mechanism having a double-supported beam structure with a drive voltage of 5 V, high-speed spatial light modulation with good contrast was able to be performed.

(Embodiment 2) In the configuration of Embodiment 1,
A layer containing light-scattering titanium oxide fine particles was provided as a processing for inhibiting total reflection and a reflection control member layer. Specifically, a light-scattering resin layer was obtained by mixing fine particles of anatase type titanium oxide with a photosensitive resist material and patterning the mixture with photolithography. By injecting the same incident light as in the first embodiment and selectively driving it with an applied voltage of 10 V, it was possible to perform high-speed spatial light modulation with good contrast.

(Embodiment 3) A spatial light modulator was constructed by combining the spatial light modulator of Embodiment 3 with a scanning mechanism of the galvano system in the configuration shown in FIG. The scanning angle of the scanning mechanism is 20
°. Regarding the arrangement of the light source and the spatial light modulator, even when the scanning mechanism is driven, the incident angle from the light source is measured from the normal direction of the total reflection surface (θ in the figure) is in the range of 40 ° to 60 °. It was arranged as follows. Using a white light source as the incident light and driving the spatial light modulator and the scanning mechanism based on the image signal, a moving image could be displayed on the screen.

(Embodiment 4) An image display apparatus having the configuration shown in FIG. 7 was manufactured by assembling the spatial light modulator of Embodiment 1 on a galvano scanning mechanism. Using a laser (wavelength: 670 nm) as the incident light and driving the spatial light modulator and the scanning mechanism based on the image signal, a moving image could be displayed on the screen.

(Embodiment 5) A width of 100 μm and a length of 5 m
Aluminum was vapor-deposited on the front and back surfaces of the piezoelectric ceramics m, and carbon black was formed as a reflection control member on the front surface side by sputtering. Next, grooves were cut at 100 μm intervals in the longitudinal direction to form a one-dimensional array. The same quartz prism as in Embodiment 1 is provided thereon,
It was a spatial light modulator. The same incident light as that of the first embodiment is incident from the incident surface, and the voltage (20) is selectively applied to the piezoelectric ceramics.
By applying V), high-speed spatial light modulation with good contrast could be performed.

(Embodiment 6) Aluminum was deposited on the front and back surfaces of a 10 mm × 10 mm piezoelectric ceramic, and carbon black was formed as a reflection control member on the front surface side by sputtering. Next, 100μ vertically and horizontally
Grooves were cut at m intervals to form a two-dimensional array. As a light guide member, a triangular prism-shaped quartz glass prism having a length of 15 mm and a regular triangle having a side of 15 mm (the same processing as in Embodiment 1 was performed on the total reflection surface) was prepared, and the form shown in FIG. 8 was used. Assembled. A laser beam (wavelength 670 nm) shaped into 10 mm × 10 mm was incident as shown in FIG. 8, and a voltage (20 V) was applied to the piezoelectric ceramics according to an image signal, whereby an image could be displayed on a screen. .

(Embodiment 7) As a light guide member, quartz glass is polished to form an equilateral triangle having a cross section of 5 mm and a length of 1 mm.
A 0 mm regular triangular prism was produced. Next, a reflection control member and its driving mechanism were manufactured as follows. FIG.
First, a silicon oxide layer 151 was formed on the surface of the silicon substrate 150 by heat treatment, and a groove was formed by dry etching.

The depth of the groove is set so that the distance between the surface of the reflection control member layer formed in the subsequent step and the total reflection surface of the light guide member integrated in the subsequent step is longer than the distance at which the evanescent wave leaks. Is set. Here, the depth of the groove was 0.6 μm. The width L of the groove corresponds to the beam length of the doubly supported beam made of the elastic material layer produced in a later step, and was 200 μm here. The length in the paper depth direction is 5 mm.

The conductive layer 153 was formed thereon by vapor deposition. The conductive layer material is desirably a high-conductivity refractory metal or alloy such as tungsten, molybdenum, or tantalum.
Here, tungsten was used. Furthermore, the CVD
A separation layer was formed by the method. The separation layer is a layer that is selectively etched in a later step so that the elastic layer formed thereon can move. As a material of the separation layer, usually, an impurity-added glass such as a phosphor silicate glass or a boron phosphor silicate glass is used. Here, the phosphor silicate glass is used.

Next, the conductive layer and the separation layer were left only at the bottom of the groove by patterning and etching with a photoresist material. Further, as shown in FIG. 12, an elastic material layer 155 constituting a doubly supported beam is formed. The elastic material layer has a role of a spring that bends upward due to the electrostatic repulsion and quickly returns downward when the electrostatic force is released. The elastic material used for the elastic material layer preferably has such a spring force. Here, the elastic material is formed by CVD using silicon nitride. The electrode layer 158 is formed on the upper surface of the elastic material layer. Here, it was formed by an evaporation method using aluminum.

Next, a reflection control member layer 156 is formed. The reflection control member, as described above, the total reflection surface of the light guide member,
A non-total reflection state is obtained by absorbing or scattering light rays or guiding light rays in a direction other than the light guide member direction.
Here, a carbon black layer was formed by sputtering. Next, as shown in FIG. 13, patterning and etching with a photoresist material were performed to separate each doubly supported beam and to remove the separation layer. At that time, the width of the doubly supported beam was set to 80 μm, and the interval between each doubly supported beam was set to 4 μm. The conductive layer 153 is used as a common electrode, and an electrode is extracted from the electrode layer of each doubly supported beam.

Finally, a one-dimensional spatial light modulator was manufactured in combination with a quartz prism as a light guiding member. In the state where no signal is input to the electrode, the spatial light modulator manufactured as described above is in the state of total reflection because the reflection control member layer is separated from the total reflection surface of the light guide member as shown in FIG. When a voltage of the same sign is applied to the conductive layer and the electrode layer of the selected doubly supported beam, the doubly supported beam is deformed as shown in FIG. 15 so that the reflection control member layer contacts the total reflection surface, and the non-total reflection state is set. Become. In the present embodiment, a laser (wavelength: 670 nm) shaped by a lens so that the beam shape becomes 1 mm × 5 mm is incident from the incident surface of the quartz prism, and a driving voltage of 10 V is used to selectively drive a doubly supported beam. By operating, high-speed spatial light modulation with good contrast could be performed.

(Embodiment 8) In Embodiment 7, except for the conductive layer 153, a layer containing light-scattering titanium oxide fine particles is provided as the reflection control member layer 156. Specifically, a light-scattering resin layer was obtained by mixing fine particles of anatase type titanium oxide with a photosensitive resist material and patterning the mixture with photolithography. In addition, the total reflection surface of the quartz prism,
An O film was formed, and patterning and etching were performed with a photoresist material to form a transparent conductive layer 159 shown in FIG. Embodiment 7 describes materials and manufacturing methods of other layers.
A one-dimensional spatial light modulator was manufactured using the same device as described above.

In the spatial light modulator manufactured as described above, when no signal is input to the electrode, the reflection control member layer is separated from the total reflection surface of the light guide member as shown in FIG. Become. When a voltage having a different sign is applied to the transparent conductive layer and the electrode layer of the selected doubly supported beam, the doubly supported beam is deformed by electrostatic attraction as shown in FIG. It comes into contact with the conductive layer and enters a non-total reflection state. By injecting the same incident light as in the seventh embodiment and selectively driving it with an applied voltage of 10 V, it was possible to perform high-speed spatial light modulation with good contrast.

(Embodiment 9) A spatial light modulator was constructed by combining the spatial light modulator of Embodiment 7 with a scanning mechanism of the galvano system in the configuration shown in FIG. The scanning angle of the scanning mechanism is 20
°. The arrangement of the light source and the spatial light modulator is such that, even when the scanning mechanism is driven, the angle of incidence from the light source is in the range of 40 ° to 60 ° (θ in FIG. 4) measured from the normal direction of the total reflection surface. It was arranged so that it might become. Using a white light source as the incident light and driving the spatial light modulator and the scanning mechanism based on the image signal, a moving image could be displayed on the screen.

(Embodiment 10) An image display device having the structure shown in FIG. 8 was manufactured by assembling the spatial light modulator of Embodiment 7 on a galvano scanning mechanism. Using a laser (wavelength: 670 nm) as the incident light and driving the spatial light modulator and the scanning mechanism based on the image signal, a moving image could be displayed on the screen.

(Embodiment 11) Aluminum was deposited on the front and back surfaces of a 10 mm × 10 mm piezoelectric ceramic, and carbon black was formed as a reflection control member on the front surface side by sputtering. Next, 100
The grooves were cut at μm intervals to form a two-dimensional array. A triangular prism-shaped quartz glass prism having a length of 15 mm and a regular triangle having a side of 15 mm was prepared as a light guide member, and assembled in the form shown in FIG. Laser light (wavelength 670 nm) shaped into 10 mm × 10 mm was incident as shown in FIG. 9 and an image was displayed on the screen by applying a voltage (20 V) to the piezoelectric ceramics in accordance with an image signal. .

[0081]

As described above, according to the present invention,
Light can be switched by extraction / non-extraction of the evanescent wave on the total reflection surface, so that the response speed is high, and since the total reflection surface has been processed to remove dark leakage light, S
An optical switching element having a high / N ratio can be provided.

Further, according to the present invention, the processing to be applied to the total reflection surface is a processing to impart light absorbing ability.
An optical switching element that can be easily manufactured can be provided.

Further, according to the present invention, the processing to be performed on the total reflection surface is a processing to impart light scattering ability.
An optical switching element having high durability can be provided.

Further, according to the present invention, the processing to be performed on the total reflection surface is a processing for imparting light transmittance, and it is possible to guide incident light in a direction other than the direction of the light guide member. Because of the processing, an optical switching element capable of further increasing the S / N ratio can be provided.

Further, according to the present invention, the light can be switched by extracting / non-extracting the evanescent wave on the total reflection surface, so that the response speed is high, and the reflection control member leaks the evanescent wave when no drive signal is applied. Since it is at a position other than the first position which is shorter than the distance, the number of times of driving can be reduced and an optical switching element having a long life can be provided.

Further, according to the present invention, the reflection control member for extracting the evanescent wave to make a non-total reflection state includes at least a light absorbing material.
It is possible to provide an optical switching element that operates at high speed with little dependence on the incident angle.

Further, according to the present invention, since the reflection control member includes at least a light scattering material, an optical switching element having higher durability can be provided in addition to the above.

Further, according to the present invention, since the reflection control member is made of a light-transmitting material and guides incident light in a direction other than the direction of the light guide member, the S / N ratio is higher. An optical switching element can be provided.

Further, according to the present invention, since the optical switching elements are arranged in a two-dimensional array, the response speed is high,
A spatial light modulator having a high S / N ratio can be provided.

Further, according to the present invention, the spatial light modulators are arranged in a one-dimensional array, so that a high manufacturing yield and a low cost can be provided.

Further, according to the present invention, a driving mechanism having a plane arranged in a one-dimensional array and rotating the plane about one axis parallel to the alignment direction of the optical switching elements is provided. Therefore, it is not necessary to separately provide a scanning device, and a small-sized spatial light modulator can be provided at a lower cost.

Further, according to the present invention, since the image formed by the spatial light modulator is projected onto the screen, high-speed modulation is possible, so that the display capacity can be increased and the image display device having a high contrast ratio can be provided. Can be provided.

Further, according to the present invention, a light beam emitted from the spatial light modulator is scanned in the vertical direction and projected on a screen to obtain a two-dimensional image, thereby providing a low-cost image display device. be able to.

Further, according to the present invention, since the image formed by the spatial light modulator is projected on the screen, it is possible to provide a small-sized image display device at lower cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an operation mechanism of a reflection control member of an optical switching element according to the present invention.

FIG. 2 is another explanatory diagram showing an operation mechanism of the reflection control member of the optical switching element according to the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a light guide member of the optical switching element according to the present invention.

FIG. 4 is an explanatory diagram showing a relationship between an incident surface and a total reflection surface of the optical switching element according to the present invention.

FIG. 5 is an explanatory view showing another embodiment of the reflection control member of the optical switching element according to the present invention.

FIG. 6 is an explanatory diagram showing a configuration of an image display device according to the present invention.

FIG. 7 is an explanatory diagram showing another configuration of the image display device according to the present invention.

FIG. 8 is an explanatory diagram showing a configuration of a spatial light modulator according to the present invention.

FIG. 9 is an explanatory diagram showing a method for manufacturing the reflection control member and the reflection control member driving mechanism of the optical switching element according to the present invention.

FIG. 10 is another explanatory view showing a method for manufacturing the reflection control member and the reflection control member driving mechanism of the optical switching element according to the present invention.

FIG. 11 is another explanatory view showing the method for manufacturing the reflection control member and the reflection control member driving mechanism of the optical switching element according to the present invention.

FIG. 12 is an explanatory diagram showing a method for forming an optical switching element or a spatial light modulator according to the present invention.

FIG. 13 is another explanatory view showing a method for forming an optical switching element or a spatial light modulator according to the present invention.

FIG. 14 is another explanatory diagram showing the method of forming the spatial light modulator according to the present invention.

FIG. 15 is another explanatory view showing a method for manufacturing the reflection control member and the reflection control member driving mechanism of the optical switching element according to the present invention.

FIG. 16 is another explanatory view showing the method for manufacturing the reflection control member and the reflection control member driving mechanism of the optical switching element according to the present invention.

FIG. 17 is another explanatory view showing the method for manufacturing the reflection control member and the reflection control member drive mechanism of the optical switching element according to the present invention.

FIG. 18 is another explanatory view showing the method of forming the optical switching element or the spatial light modulator according to the present invention.

FIG. 19 is another explanatory diagram showing the method of forming the optical switching element or the spatial light modulator according to the present invention.

FIG. 20 is another explanatory diagram illustrating the method of forming the optical switching element or the spatial light modulator according to the present invention.

FIG. 21 is another explanatory diagram showing the method of forming the optical switching element or the spatial light modulator according to the present invention.

FIG. 22 is an explanatory diagram illustrating a configuration of an optical switching element according to a conventional technique.

FIG. 23 is an explanatory diagram of an operation of the optical switching element according to the related art.

FIG. 24 is an explanatory diagram showing an example of a projection device using the optical switching element shown in FIG.

[Explanation of symbols]

 Reference Signs List 101 light guide member 102 incident surface 103 total reflection surface 104 emission surface 107 reflection control member 108 incident light 112 processing for inhibiting total reflection 120 spatial light modulator 150 silicon substrate 151 silicon oxide layer 152 silicon nitride layer 153 conductive layer 154 sacrificial layer 155 elastic material layer 156 reflection control member layer 157 gap 158 electrode layer 159 transparent conductive layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Mayuka Nagata 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H041 AA11 AA16 AB40 AC06 AZ01 AZ08 5C058 AA18 BA23 BA35 EA13 EA27 EA54

Claims (14)

[Claims] A light guide member having a light incident surface, a light exit surface, and a surface having a portion capable of totally reflecting incident light in a direction substantially corresponding to a light exit surface (hereinafter, referred to as a total reflection surface); A position where the incident light on the total reflection surface of the light guide member is irradiated, a first position that is equal to or less than a distance at which the evanescent wave leaks, and a reflection control member movable to other positions and a driving unit that drives the reflection control member An optical switching element, characterized in that a part or all of the total reflection surface other than the part where the reflection control member faces is subjected to processing for inhibiting total reflection. 2. The optical switching element according to claim 1, wherein the processing for inhibiting total reflection is a processing for imparting light absorbing ability. 3. The optical switching element according to claim 1, wherein the processing for inhibiting the total reflection is a processing for imparting a light scattering ability. 4. The method according to claim 1, wherein the processing for inhibiting total reflection is processing for imparting light transmittance, and processing for enabling incident light to be guided in a direction other than the direction of the light guide member. The optical switching element according to claim 1, wherein 5. A light guide member including a light incident surface, a light exit surface, and a surface having a portion capable of totally reflecting incident light in a direction substantially corresponding to a light exit surface (hereinafter, referred to as a total reflection surface). A position where the incident light on the total reflection surface of the light guide member is irradiated, a first position which is equal to or less than a distance at which the evanescent wave leaks, and a reflection control member movable to other positions and a drive for driving the reflection control member An optical switching element, wherein the reflection control member is located at a position other than the first position which is equal to or less than a distance at which an evanescent wave leaks when a drive signal is not applied. 6. The optical switching element according to claim 1, wherein the reflection control member includes at least a light absorbing material. 7. The optical switching element according to claim 1, wherein the reflection control member includes at least a light scattering material. 8. The reflection control member according to claim 1, wherein the reflection control member is made of a light-transmitting material, and guides incident light in a direction other than the direction of the light guide member. The optical switching element according to any one of the above. 9. A spatial light modulator, wherein the optical switching elements according to claim 1 are arranged in a two-dimensional array. 10. A spatial light modulator, wherein the optical switching elements according to claim 1 are arranged in a one-dimensional array. 11. The 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. 12. The spatial light modulator according to claim 9, a unit for causing a light beam to enter the spatial light modulator, and a unit for projecting and displaying an image formed by the spatial light modulator on a screen. An image display device comprising: 13. A spatial light modulator according to claim 10, wherein: a means for causing a light beam to enter the spatial light modulator; and a light beam emitted from the spatial light modulator to an optical switching element of the spatial light modulator. An image display device comprising: a scanning mechanism that scans in a direction perpendicular to the alignment direction; and a unit that projects a light beam emitted from the scanning mechanism onto a screen and displays the screen. 14. A spatial light modulator according to claim 11, further 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. An image display device comprising: