JP2004347693A - Microlens array, spatial optical modulator, projector and method for manufacturing microlens array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microlens array capable of restraining the occurrence of stray light by efficiently condensing light at a predetermined position. <P>SOLUTION: The microlens array 100 has a plurality of microlens elements 10 each consisting of: a 1st surface S1 disposed on a light incident side and having curvature; and a 2nd surface S2 having nearly plane shape on which the light transmitted through the 1st surface S1 is made incident. The microlens elements 10a are arrayed on a reference plane 20 having a predetermined area. When the nearly center position of the area of the 2nd surface S2a is defined as a reference center position Ca, and a position obtained by projecting a contact between the 1st surface S1a of the microlens element 10a and a plane Ba coming into contact with the 1st surface S1a when the plane Ba and the reference plane 20 are nearly parallel with each other to the reference plane 20 is defined as a top curvature position Ta respectively, the 1st surface S1a has such curvature that the reference center position Ca of the microlens element 10a and the top curvature position Ta are made to differ by a predetermined distance in a predetermined direction in accordance with the reference center position Ca on the reference plane 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a microlens array, a spatial light modulator, a projector, and a method of manufacturing a microlens array, and more particularly, to a technique of a microlens array used for a spatial light modulator of a projector.
[0002]
[Prior art]
A projector is an image display device that projects light (projection light) in accordance with an image signal supplied from an image supply device from a computer or the like, and displays an image. A spatial light modulation device of a projector has a plurality of spatial light modulation elements. An opening or a reflecting surface is provided at the center of each spatial light modulation element. Each spatial light modulation element transmits or reflects light incident on the opening or the reflecting surface. When each of the spatial light modulators transmits or reflects the incident light, the spatial light modulator modulates the incident light. A microlens array is provided on the light incident side of the spatial light modulator. The microlens array has a plurality of microlens elements arranged on a reference plane. Each microlens element condenses light on an opening or a reflective surface of each spatial light modulation element. Since the microlens element condenses the incident light on the opening or the reflection surface of the spatial light modulator, the light from the light source can be efficiently used for modulation. The technology of the microlens array used in the spatial light modulator of the projector has been proposed by the same applicant as the present application (for example, Japanese Patent Application No. 2002-171892).
[0003]
[Problems to be solved by the invention]
For example, a fly-eye integrator is used to make the light from the light source unit uniform in intensity and then to make the light from the incident light source unit uniform in the spatial light modulator. The fly-eye integrator has a plurality of lens elements. The fly-eye integrator projects the light that enters the incident surface of each lens element onto the entire exposure surface, and superimposes the light from each lens element to make the illuminance distribution of the light on the exposure surface uniform. For this reason, the light from each lens element of the fly-eye integrator irradiates the microlens array provided on the incident side of the conventional spatial light modulator in a superimposed manner.
[0004]
Each microlens element has a refracting surface having a curvature substantially rotationally symmetric with respect to the optical axis of each microlens element. Then, the microlens array condenses the light incident on each microlens element at each focal position. The microlens array is arranged such that the opening or the reflection surface of the spatial light modulator is located near the focal position of the microlens element.
[0005]
The distribution of the incident angle of the incident light near the center of the region of the microlens array is substantially rotationally symmetric with respect to the optical axis of the microlens element. Therefore, the microlens elements arranged near the center of the region of the microlens array focus the incident light near the focal position on the optical axis as described above. On the other hand, in the peripheral area where the microlens array is arranged, for example, the proportion of illumination light from a fly-eye type integrator obliquely incident on each optical axis of the microlens element from a specific direction increases. Will come. The light beam obliquely incident on the microlens element is focused on another focal position on the focal plane of the microlens element. For this reason, it is difficult for the light obliquely incident on the microlens element to enter the opening of the spatial light modulator provided near the focal position on the optical axis of the microlens element. Further, in an apparatus constituted by a plurality of optical members such as a projector, light may be kicked in the optical system in front of the spatial light modulator. As a result, there arises a problem that utilization efficiency of light transmitted through the microlens array is reduced. The problem that the light use efficiency is reduced is particularly remarkable in the microlens elements arranged in the outer peripheral arrangement portion.
[0006]
When a liquid crystal panel is used as the spatial light modulator, various wirings, electric elements, and the like for driving the spatial light modulator are provided in portions other than the openings of the spatial light modulator. Light incident on a portion other than the opening of the spatial light modulator may be reflected by a portion other than the opening of the spatial light modulator, thereby generating stray light in some cases. The occurrence of stray light may lower the contrast of the projected image. In addition, as a characteristic of the liquid crystal, the contrast may be reduced due to an increase in light components at a large angle with respect to the optical axis. The present invention has been made in view of the above-described problems, and efficiently condenses light at a predetermined position, reduces a generation of stray light, a microlens array, a spatial light modulator including the microlens array, An object of the present invention is to provide a projector and a method for manufacturing the microlens.
[0007]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, according to the present invention, a first surface having a curvature provided on an incident side of incident light, and a substantially transparent surface through which the incident light incident on the first surface is transmitted. A microlens array having a plurality of microlens elements each including a second surface having a planar shape, wherein the plurality of microlens elements are arranged on a reference plane having a predetermined region, and A position substantially at the center of the surface area is defined as a reference center position, and the plane contacting the first surface and the second surface when the plane contacting the first surface of the microlens element and the reference plane are substantially parallel to each other. When a position where a contact point with one surface is projected on the reference plane is defined as a vertex curvature position, the first surface is positioned on the base plane in accordance with the reference center position of the microlens element on the reference plane. Can be the center position and said apex of curvature located to provide a microlens array and having a predetermined distance as distinct of curvature in a predetermined direction.
[0008]
Each microlens element has a first surface having a curvature and a second surface that is in contact with a reference plane of the microlens array. For example, the first surface of the microlens element substantially at the center of the reference plane has a substantially rotationally symmetric shape with respect to a perpendicular passing through the reference center. In this case, the microlens element substantially at the center position of the reference plane condenses the light traveling in a direction substantially parallel to the optical axis near the on-axis focal position on a perpendicular line passing through the reference center position. The “reference center position” is a position substantially at the center of the region on the second surface of the microlens element. The opening or the reflecting surface of the spatial light modulator is arranged on a perpendicular passing through the reference center position. For this reason, the microlens element substantially at the center position of the reference plane focuses the light traveling in a direction substantially parallel to the optical axis on the opening or the reflecting surface of the spatial light modulator. Next, the first surface on the incident side of the microlens element in the outer peripheral portion of the microlens array has a curvature such that the reference center position and the vertex curvature position of the microlens element are different by a predetermined distance in a predetermined direction. The “vertex curvature position” means that a contact point between the plane contacting the first surface and the first surface is projected onto the reference plane when the plane contacting the first surface of the microlens element is substantially parallel to the reference plane. Position. In other words, the “vertex curvature position” is a position where a point on the first surface farthest from the second surface in a direction perpendicular to the reference plane is projected on the second surface. When the reference center position and the vertex curvature position of the microlens element are the same, the first surface has a substantially rotationally symmetric shape with respect to a perpendicular passing through the reference center position of the second surface. “The reference center position of the microlens element is different from the vertex curvature position” means that the first surface has an asymmetric shape with respect to a perpendicular passing through the reference center position. The shape that is asymmetrical with respect to a perpendicular passing through the reference center position is a shape that is inflected in a certain direction. The microlens element has a curved shape such that incident light obliquely incident from a direction in which the first surface is curved is condensed at an axial focal position of the microlens element. The microlens element can condense the obliquely incident light to the axial focal position by bending the first surface in the direction of the obliquely incident light. For each microlens element other than the microlens element substantially at the center position of the reference plane, the first surface has a curvature such that the reference center position and the vertex curvature position are different by a predetermined distance in a predetermined direction. In this way, the obliquely incident light is condensed at the on-axis focal position on a perpendicular passing through the reference center position. Thereby, light can be efficiently incident on the opening or the reflecting surface of the spatial light modulator. In addition, light rays incident on the protruding portion of the microlens element from an oblique direction are angle-converted to light rays that are substantially parallel to the direction of the optical axis, thereby suppressing kicking in the front optical system and improving light use efficiency. Contribute. Further, the occurrence of stray light can be reduced in order to prevent light from entering various wirings, electric elements, and the like of the spatial light modulator.
[0009]
The incident angle of obliquely incident light and the obliquely incident direction of light incident on the microlens array differ depending on the position of the microlens element on the reference plane of the microlens array. Light incident on the microlens elements located on the outer peripheral portion of the microlens array has a large proportion of light obliquely incident. Further, the ratio of obliquely incident light increases as the distance from the center position of the reference plane increases. Therefore, it is assumed that the predetermined direction between the reference center position and the vertex curvature position and the predetermined distance between the reference center position and the vertex curvature position correspond to the position of the microlens element on the reference plane of the microlens array. By associating the predetermined direction between the reference center position and the vertex curvature position and the predetermined distance between the reference center position and the vertex curvature position with the position of the microlens element, the microlens element is positioned on the reference plane. Light obliquely incident at different angles depending on the position can be focused on the opening or the reflecting surface of the spatial light modulator. Thereby, it is possible to obtain a microlens array that efficiently condenses light on the opening or the reflecting surface of the spatial light modulation element and reduces generation of stray light.
[0010]
In a preferred aspect of the present invention, the distance between the reference center position of the microlens element and a predetermined position on the reference plane, the reference center position of the microlens element, the microlens element It is desirable that the predetermined distance between the position and the apex curvature position is substantially proportional.
[0011]
As described above, the ratio of the light obliquely incident on the microlens element increases at the position of the outer peripheral arrangement portion distant from the center position of the microlens array. Therefore, the distance between the reference center position of the microlens element and a predetermined position on the reference plane, for example, the approximate center position of the reference plane, and the distance between the reference center position and the vertex curvature position of the microlens element Are set at the apex curvature positions of the microlens elements so that the above is approximately proportional. When the distance between the reference center position of the microlens element and the apex curvature position is increased, the first surface of the microlens element has an inflected shape that protrudes more. Therefore, as the distance between the reference center position of the microlens element and the approximate center position of the reference plane increases, the first surface of the microlens element has an inflected shape that protrudes more. When the first surface of the microlens element has an inflected shape such that it protrudes more, the oblique incident light having a larger incident angle is condensed near the on-axis focal position on a perpendicular line passing through the reference center position. Can be. Thereby, according to the distance between the reference center position of the microlens element and the approximate center position of the reference plane, the light having a large angle of oblique incidence of the incident light on the microlens array element is changed to the opening of the spatial light modulator or Light can be collected on the reflecting surface. As a result, light can be efficiently condensed on the opening or the reflecting surface of the spatial light modulator, and the generation of stray light can be reduced. The predetermined position is not limited to the substantially center position of the reference plane, but may be any position on the reference plane.
[0012]
In a preferred aspect of the present invention, an orientation of a predetermined position on the reference plane with respect to the reference center position of the micro lens element, and a vertex curvature position of the micro lens element with respect to the reference center position of the micro lens element Is desirably the same as the direction.
[0013]
As described above, the ratio of light obliquely incident on the microlens array increases at the position of the outer peripheral arrangement portion of the microlens array. Therefore, the vertex curvature position of the microlens element is provided so that the direction of the vertex curvature position with respect to the reference center position is the same as the predetermined position with respect to the reference center position, for example, the direction of the approximate center position of the reference plane. The first surface of the microlens element has an inflected shape such that it protrudes in the direction of the vertex curvature position of the microlens element with respect to the reference center position of the microlens element. Therefore, the first surface of the microlens element has a curvature such that it protrudes from the reference center position of the microlens element to the substantially center position of the reference plane. By providing such a curvature, the microlens element can condense the obliquely incident light in the vicinity of the on-axis focal position on a vertical line passing through the reference center position. Thereby, depending on the direction of the reference center position of the microlens element with respect to the substantially center position of the reference plane, the obliquely incident light having a large incident angle among the light incident on the microlens element is applied to the opening or the reflection surface of the spatial light modulator. Light can be collected. As a result, light can be efficiently condensed on the opening or the reflecting surface of the spatial light modulator, and the generation of stray light can be reduced.
[0014]
In a preferred aspect of the present invention, it is preferable that the plurality of microlens elements are arranged in a lattice shape that is substantially orthogonal on the reference plane. The modulators of the spatial light modulator are arranged in a substantially orthogonal lattice on a reference plane. By arranging the microlens elements in a grid shape that is substantially orthogonal on the reference plane, light can be efficiently condensed on the opening of the modulation unit or on the reflection surface. Accordingly, light can be efficiently condensed at a predetermined position which is an opening or a reflection surface of the modulation section, and generation of stray light can be reduced.
[0015]
Further, according to the present invention, there is provided a microlens array in which a plurality of microlens elements having a function of deflecting light are arranged on a reference plane, wherein the microlens element has a first surface having a curvature, A second surface having a substantially planar shape through which incident light incident on the first surface is transmitted, and a position of substantially the center of each of the regions of the second surface of the microlens element is defined as a reference center position; When the position where the substantially parallel surface and the first surface are in contact with each other is defined as a curvature vertex, the reference center position and the position where the curvature vertex is projected on the reference plane include a microlens element. A featured microlens array can be provided.
[0016]
For example, when a microlens element having a first surface that is substantially rotationally symmetric with respect to a perpendicular passing through the reference center position is arranged at the position of the outer peripheral arrangement portion of the reference plane, the other microlens elements are located at positions on the reference plane. The positions of the vertices of curvature are provided differently in accordance with this. The microlens element makes the first surface bend in the direction by making the reference center position different from the position where the curvature vertex is projected on the reference plane, so that the obliquely incident light can be efficiently shifted to the axial focal position. Light can be collected. In this way, a microlens array capable of efficiently condensing light on the opening or the reflecting surface of the spatial light modulator according to the angular distribution of the incident light incident on the microlens array can be obtained.
[0017]
Further, according to the present invention, a resist layer forming step of forming a resist layer on a substrate, a first patterning step of patterning the resist layer, and a first etching step of pre-etching the resist layer and the substrate A mask layer forming step of forming a mask layer on the substrate pre-etched in the first etching step, and a second patterning step of patterning the mask layer formed in the mask layer forming step A second etching step of etching the substrate through a pattern formed by the second patterning step; a center position of the pattern formed by the first patterning step; and a second patterning step. Characterized in that the position is different from the center position of the pattern formed by Method of manufacturing that the microlens array can be provided.
[0018]
The center position of the pattern formed on the substrate in the first etching step is different from the center position of the pattern formed on the mask layer in the second etching step. In addition, a sacrificial layer having a higher etching rate than the substrate can be used over the substrate that has been pre-etched in the first etching step. By using the sacrifice layer having an etching rate higher than that of the substrate, the sacrifice layer is quickly etched at the concave portion formed in the substrate in the second patterning step. The etching proceeds around the through portion formed by the second patterning step. When the etching progress site reaches the concave portion of the substrate, the sacrificial layer inside the concave portion of the substrate is etched earlier than the substrate. Since the position of the through portion of the mask layer, which is the etching center, is different from the position of the concave portion of the substrate, the substrate can be formed with an asymmetric concave portion in which the concave position of the substrate is deflected so as to be depressed. . Thereafter, by forming an optically transparent resin layer on the asymmetrical concave portion formed on the substrate, a microlens element having a curvature different from the reference center position and the vertex curvature position on the first surface can be formed. . By setting the horizontal position of the concave portion by the patterning of the mask layer with respect to the concave position of the substrate to a predetermined position, the vertex curvature position with respect to the reference center position on the first surface of the microlens element can be set on the reference plane of the microlens array. The position can be set in a predetermined direction according to the position of the lens element. Further, by setting the horizontal distance between the concave portion position of the substrate and the concave position formed by patterning of the mask layer to a predetermined distance, the vertex curvature position with respect to the reference center position for the first surface of the microlens element can be determined with respect to the microlens array reference position. The position can be a predetermined distance corresponding to the position of the microlens element on the plane. Thus, the above-described microlens array can be manufactured.
[0019]
Further, according to the present invention, the micro lens array for condensing the incident light, and a spatial modulation element for modulating the incident light condensed by the micro lens array, the micro lens array, It is possible to provide a spatial light modulator that is arranged on the incident side of the spatial light modulator. Since the microlens array is provided on the incident side, incident light can be efficiently condensed on the opening. Thereby, an efficient spatial light modulator can be obtained.
[0020]
Further, according to the present invention, a light source unit that supplies light, a spatial light modulator that modulates light from the light source unit according to an image signal, and a projection that projects light modulated by the spatial light modulator And a lens, wherein the spatial light modulator is the spatial light modulator described above.
[0021]
By providing the microlens array on the incident side of the spatial light modulator, light from the light source unit can be efficiently condensed on the opening or the reflective surface of the spatial light modulator. Thereby, the light use efficiency of the projector can be improved. The liquid crystal device, which is a spatial light modulator, has a characteristic that the contrast is improved when the incident angle of the incident light is parallel to the optical axis direction. Therefore, by making the shape of the microlens element in the outer peripheral portion of the microlens array asymmetric and making the refraction angle of the incident light parallel to the optical axis, it contributes to the improvement of the contrast. Further, it is possible to prevent light from being incident on a portion other than the opening of the spatial light modulation element, in which various wirings and electric elements are provided. Accordingly, it is possible to prevent light from being reflected by various wirings and electric elements of the spatial light modulation element, and to reduce generation of stray light. As a result, a projector with a bright projected image and high contrast can be obtained. Note that the projector of the present invention is not limited to a projector in which light from a light source unit is superimposedly irradiated by a fly-eye integrator to make the light uniform. If the use efficiency of light from the light source unit can be improved by using the above-described microlens array, a projector using a device other than a fly-eye integrator is included in the projector of the present invention. I do.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1st Embodiment)
FIG. 1 shows a schematic configuration of the microlens array according to the first embodiment. Note that the microlens array 100 of the present embodiment will be described as applied to a liquid crystal display device that is a spatial light modulator of a projector. The microlens array 100 is disposed on a reference plane 20 in a predetermined area substantially perpendicular to the Z direction which is the optical axis direction and substantially parallel to the XY plane. The microlens array 100 has a plurality of microlens elements 10 arranged on a reference plane 20. The plurality of microlens elements 10 are arranged in a substantially orthogonal lattice on the reference plane 20. For the sake of understanding the microlens array 100 of the present invention, the following description will be made assuming that the microlens elements 10 are arranged in 5 rows and 5 columns on the reference plane 20 of the microlens array 100. In the microlens array 100 shown in FIG. 1, five microlens elements 10 are arranged in a row in the X direction and five in a row in the Y direction on the reference plane 20.
[0023]
Each microlens element 10 is provided on a side on which incident light is incident, and includes a first surface S1 having a curvature and a second surface S2 having a substantially planar shape through which the incident light incident on the first surface is transmitted. In FIG. 1, each microlens element 10 is indicated by the outline (outer peripheral arrangement portion) of the second surface S2. The outline of the second surface S2 of each microlens element 10 is substantially circular. Each microlens element 10 is arranged such that the second surface S2 is in contact with the reference plane 20. Also, FIG. 1 does not show the first surface S1 of each microlens element 10. The first surface S1 of each microlens element 10 has a curvature with its convex surface directed in the negative direction of the Z axis with respect to the second surface S2. As will be described later, light incident on the microlens array 100 is incident on the first surface S1 of the microlens element 10 and exits from the second surface S2. The micro lens array 100 sets the center position O as a substantially center position of the reference plane 20. The optical axis OZ of the light incident on the microlens array 100 passes through the center position O of the reference plane 20 and is an axis parallel to the Z axis. The details of the reference center position C, the vertex curvature position T, and the distance D of the microlens element 10 will be described later.
[0024]
FIG. 2 shows a cross section of the microlens array 100 along the line AA ′ shown in FIG. 1 viewed from the plus direction of the X axis. The five microlens elements 10 arranged on the straight line AA ′ shown in FIG. 1 are microlens elements 10a, 10b, 10c, 10d, and 10e, respectively, as shown in FIG. The five microlens elements 10a to 10e respectively have first surfaces S1a, S1b, S1c, S1d, and S1e having curved surfaces, and second surfaces S2a, S2b, S2c, S2d, and S2e that are planes that are in contact with the reference plane 20. Having. The micro lens array 100 is arranged so that the reference plane 20 and the spatial light modulator 200 are in contact with each other. The five microlens elements 10a to 10e condense incident light to the openings Ka, Kb, Kc, Kd, and Ke of the liquid crystal display device 200, respectively. The incident light of the microlens array element 10 and the manner in which the incident light is focused on the openings Ka to Ke of the liquid crystal display device 200 will be described later.
[0025]
Next, how the light from the light source irradiates the microlens array 100 will be described. FIG. 3A schematically illustrates a configuration example until light from the light source unit irradiates the spatial light modulator 200. The lighting device 300 includes a light source unit 301 and a reflector 302. Light from the light source unit 301 is emitted directly or by reflecting off the reflector 302. Light from the light source unit 301 is made substantially parallel by an illumination optical system (not shown), and then enters the fly-eye integrator 310. The fly-eye integrator 310 has a first lens array 311 and a second lens array 312. Each of the first lens array 311 and the second lens array 312 has a configuration in which lens elements are arranged in a matrix on a plane. Each lens element of the first lens array 311 divides a light beam parallel to the principal ray into a plurality of partial light beams, and forms an image of each of the partial light beams near the second lens array 312. The lens elements of the second lens array 312 cause the respective partial light beams from the first lens array 311 to enter the micro lens array 100. The fly-eye integrator 310 projects the light entering the incident surface of each lens element onto the entire microlens array 100 and superimposes the light from each lens element, thereby reducing the illuminance distribution of the light in the microlens array 100. Make it even. For this reason, the light from the lens element of the fly-eye integrator 310 is irradiated onto the microlens array 100 in a superimposed manner. The micro lens array 100 is arranged on the light incident side of the spatial light modulator 200 with the first surface S1 of the micro lens element 10 facing the incident side. Further, the reference plane 20 of the microlens array 100 and the spatial light modulator 200 are arranged so as to be substantially perpendicular to the optical axis OZ. Further, the fly-eye integrator 310, the microlens array 100, and the center position of the fly-eye integrator 310 and the center position O of the reference plane 20 are arranged so as to be located substantially on the optical axis OZ. .
[0026]
Next, the relationship between the position of the microlens array 100 in the XY plane on the reference plane 20 and the incident light will be described. FIG. 3B shows the reference plane 20 of the microlens array 100 divided into nine square regions in a grid pattern. Each region obtained by dividing the microlens array 100 into nine parts will be described with numbers 1 to 9 as shown in FIG. FIG. 4 shows the distribution of the incident angle for each region of the microlens array 100 shown in FIG. 4A to 4I, the vertical axis represents the incident angle in the X direction, and the horizontal axis represents the incident angle in the Y direction. The angle distribution shown in FIG. 4A is a distribution of the incident angle of the incident light in the region 1 of the microlens array 100 shown in FIG. Hereinafter, the distributions of the incident angles shown in FIGS. 4B to 4I correspond to the regions 2 to 9 in FIG. 3B, respectively. The angle distributions shown in FIGS. 4A to 4I indicate that the distribution of the incident angle changes depending on the positions of the regions 1 to 9 on the reference plane 20 in the microlens array 100, as described later. Things. The graphs in FIGS. 4A to 4I qualitatively show the distribution of the incident angle of the incident light on the microlens array 100 for each region.
[0027]
The region 5 of the microlens array 100 shown in FIG. 3B is located substantially at the center of the reference plane 20 of the microlens array 100. FIG. 5A schematically shows how light from the fly-eye integrator 310 is superimposed on the region 5 of the microlens array 100. As shown in FIG. 5A, light from the fly-eye type integrator 310 is irradiated onto the region 5 of the microlens array 100 so as to be superimposed substantially symmetrically with respect to the optical axis OZ.
[0028]
The region 8 of the microlens array 100 shown in FIG. 3B is located in the −X direction of the region 5 located at the center of the microlens array 100 on the reference plane 20 of the microlens array 100. FIG. 5B schematically shows how light from the fly-eye integrator 310 is superimposed on the region 8 of the microlens array 100. As shown in FIG. 5B, in the region 8 of the microlens array 100, the proportion of light obliquely incident from the + X direction on the straight line L8 passing through the approximate center of the region 8 and parallel to the optical axis OZ increases. As described above, of the incident light in the region 8 of the microlens array 100, the light having the large incident angle is light obliquely incident from the + X direction.
[0029]
The distribution of the incident angle of the incident light is shown for the regions 1 to 4, the region 6, the region 7, and the region 9 of the microlens array 100 shown in FIG. (See FIGS. 4 (a) to 4 (d), (f), (g) and (i)). Note that the distribution of the incident angle of the incident light also differs depending on the position in each of the regions 1 to 9. For this reason, FIGS. 4A to 4I all show the angular distribution at the approximate center position of the regions 1 to 9 of the microlens array 100. The angle of the light beam emitted from the fly-eye integrator 310 depends on the reflector 302 of the light source unit 300 and the illumination optical system (not shown), the design of the fly-eye 312, and the installation of the microlens array 100 shown in FIG. Depends on location. For this reason, the incident angle of each light beam incident on the microlens array 100 from the fly-eye integrator 310 is determined by the reflector 302 of the light source unit 300 and the illumination optical system (not shown). Each light beam incident on the microlens array 100 of the present embodiment is aligned by the reflector 302 such that the maximum incident angle is approximately 16 °.
[0030]
Next, a reference center position C, a vertex curvature position T, and a distance D of the microlens element 10 will be described with reference to FIG. 6A to 6E show sectional views of the microlens elements 10a to 10e. 6A to 6E show the same plane as the cross section shown in FIG. The approximate center positions of the regions of the second surfaces S2a to S2e of the five microlens elements 10a to 10e are referred to as reference center positions Ca, Cb, Cc, Cd, and Ce, respectively. 6A to 6E, the vertical axis is a perpendicular line of the second surfaces S2a to S2e passing through the reference center positions Ca to Ce. In other words, the vertical axis is a straight line that passes through the reference center positions Ca to Ce and is parallel to the Z axis. The horizontal axis is a straight line in the Y direction on the reference plane 20.
[0031]
In the microlens element 10a shown in FIG. 6A, a plane Ba substantially parallel to the reference plane 20 and the first surface S1a are in contact with each other at a contact point Pa. The contact point Pa is a point on the first surface S1a farthest from the second surface S2a. The position where the contact point Pa is projected on the reference plane 20 is defined as a vertex curvature position Ta. The microlens elements 10b to 10e shown in FIGS. 6B to 6E are also similar to the microlens element 10a shown in FIG. To Be, the vertex curvature positions Tb to Te are determined. As described above, the vertex curvature positions Ta to Te are points where the points on the first surfaces S1a to S1e farthest in the Z direction from the second surfaces S2a to S2e are projected onto the second surfaces S2a to S2e.
[0032]
First, the curvature of the first surface S1c of the microlens element 10c shown in FIG. 6C will be described. The microlens element 10c is arranged at a center position O which is a predetermined position on the reference plane 20. The reference center position Cc and the vertex curvature position Tc of the microlens element 10c are the same as the center position O of the reference plane 20. The optical axis OZ of the incident light is the same as the vertical axis of the micro lens element 10c. The microlens element 10c is located substantially at the center of the region 5 of the microlens array 100 shown in FIG. As described with reference to FIG. 4E, in the region 5, the incident angles of light are substantially rotationally symmetric about the angle 0 in both the X and Y directions. Therefore, as shown in FIG. 6C, the first surface S1c of the microlens element 10c is formed to be substantially rotationally symmetric with respect to the optical axis OZ. Since the shape is substantially rotationally symmetric with respect to the optical axis OZ, the first surface S1c of the microlens element 10c is, for example, a substantially spherical surface. The microlens element 10c can condense light to an axial focal position on the optical axis OZ by making the first surface S1c substantially symmetrical with respect to the optical axis OZ.
[0033]
Next, the curvature of the first surface S1a of the microlens element 10a shown in FIG. 6A will be described. The micro lens element 10a is located at the outermost peripheral portion of the micro lens array 100. As shown in FIG. 4D, in the outer peripheral arrangement portion, the incident angle of light has a distribution centered on 0 in the X direction and positive coordinates in the Y direction. For this reason, light incident on the microlens element 10a has a large proportion of light obliquely incident from the Y direction.
[0034]
Therefore, as shown in FIG. 6A, the first surface S1a of the microlens element 10a is formed into an asymmetric shape with respect to a perpendicular to the second surface S2a passing through the reference center position Ca. The first surface S1a of the microlens element 10a is provided with a vertex curvature position Ta having a curvature such that the vertex curvature position Ta differs from the reference center position Ca by a predetermined distance in a predetermined direction. This allows the first surface Sa1 of the microlens element 10a to have an asymmetric shape with respect to a perpendicular to the second surface S2a passing through the reference center position Ca. Similarly to the case of the microlens element 10a, the microlens elements 10b, 10d, and 10e are provided with respective apex curvature positions Tb, Td, and Te to have an asymmetric shape. Hereinafter, the direction of the vertex curvature position Ta with respect to the reference center position Ca and the distance between the reference center position Ca and the vertex curvature position Ta will be described.
[0035]
As described above, the proportion of light incident on the microlens element 10a obliquely incident from the Y direction with respect to the perpendicular to the second surface S2a passing through the reference center position Ca is large. Therefore, the vertex curvature position Ta is shifted from the reference center position Ca in the positive direction in the Y direction. The positive direction in the Y direction obtained by shifting the vertex curvature position Ta from the reference center position Ca is the direction of the center position O, which is a predetermined position on the reference plane 20 with respect to the reference center position Ca. By providing the apex curvature position Ta in this way, the microlens element 10a has an asymmetric shape. The first surface S1a of the microlens element 10a having a curvature such that the vertex curvature position Ta is shifted from the reference center position Ca to the positive direction in the Y direction is inflected so as to protrude in the positive direction in the Y direction. Shape.
[0036]
Next, the distance between the reference center position and the vertex curvature position will be described using the microlens element 10a and the microlens element 10b as an example. The micro lens element 10a and the micro lens element 10b have the same orientation of the center position O, which is a predetermined position on the reference plane 20, with respect to the reference center positions Ca and Cb. Accordingly, the microlens element 10a and the microlens element 10b have a common feature that the respective vertex curvature positions Ta and Tb are shifted in the positive direction in the Y direction. On the other hand, the difference between the microlens element 10a and the center position O of the reference plane 20 is larger than the distance between the microlens element 10b and the center position O of the reference plane 20. The light from the microlens array 100 is radiated substantially rotationally symmetrically with respect to the optical axis OZ at a center position O, which is a point on the optical axis OZ on the reference plane 20. The incident angle component increases. The incident angle and oblique incident angle component of light obliquely incident on the microlens element 10a are larger than the incident angle of light obliquely incident on the microlens element 10b (see FIG. 2). Further, since the incident angle and the oblique incident angle component of the obliquely incident light increase as the distance from the center position O increases, for example, the incident angle and the oblique incident angle component of the obliquely incident light on the microlens element 10a are transmitted to the microlens element 10b. This is approximately twice the maximum value of the incident angle of obliquely incident light.
[0037]
From here, the distance between the reference center position Ca and the vertex curvature position Ta will be described with reference to FIGS. As shown in FIG. 2, the distance D2a between the center position O and the reference center position Ca is approximately twice the distance D2b between the center position O and the reference center position Cb. As shown in FIG. 6B, the distance D1b between the reference center position Cb of the microlens element 10b and the vertex curvature position Tb is the length α. At this time, the distance D1a between the reference center position Ca and the vertex curvature position Ta of the microlens element 10a is 2α in length. The length of the distance D1a is twice the length of the distance D1b. In this way, the distance D2a between the reference center position Ca and the center position O of the reference plane 20 and the distance D1a between the reference center position Ca and the vertex curvature position Ta are made substantially proportional. Thus, for the microlens element 10a, the distance D2a between the reference center position Ca and the center position O, which is a predetermined position on the reference plane 20, and the distance between the reference center position Ca and the vertex curvature position Ta. Apex curvature positions Ta and Tb are provided so that D1a is approximately proportional to D1a.
[0038]
Thus, the microlens element 10a has a shape such that the vertex curvature position Ta and the reference center position Ca differ by a predetermined distance in a predetermined direction according to the reference center position Ca of the microlens element 10a on the reference plane 20. I do. The first surface S1a of the microlens element 10a has a shape that is curved so as to protrude in the positive direction in the Y direction. The first surface S1b of the microlens element 10b also has a shape that is curved so as to protrude in the positive Y direction. Further, the first surface S1a of the microlens element 10a has an inflected shape so as to extend substantially twice as large as the first surface S1b of the microlens element 10b. By forming the first surface S1a of the microlens element 10a in such a shape, the on-axis focal position on the perpendicular to the second surface S2a that efficiently passes light obliquely incident on the microlens element 10a through the reference center position Ca Light can be collected in the vicinity. Thus, the obliquely incident light can be efficiently collected on the opening Ka (see FIG. 2) of the liquid crystal display device 200. As shown in FIGS. 6 (b), (d), and (e), the micro lens elements 10b, 10d, and 10e have the same reference center positions Cb, Cd, and C on the reference plane 20 as in the case of the micro lens element 10a. According to Ce, the shape is such that the apex curvature positions Tb, Td, Te differ from the reference center positions Cb, Cd, Ce by a predetermined distance in a predetermined direction. Thus, the light can be efficiently collected on the openings Kb, Kd, and Ke (see FIG. 2) of the liquid crystal display device 200. FIG. 1 shows that the vertex curvature positions T of the microlens elements 10 of the microlens array 100 are different from each other by a predetermined distance in a predetermined direction in the same manner as the microlens element 10a.
[0039]
FIG. 7 shows how the microlens elements 10c and 10e collect incident light. Consider a case where substantially parallel light parallel to the optical axis OZ is incident on the center position O of the microlens array 100. At the center position O of the microlens array 100, a microlens element 10c shown in FIG. 7A is provided. The first surface S1c of the microlens element 10c has a substantially symmetric shape with respect to the optical axis OZ. The microlens element 10c collects light substantially parallel to the optical axis OZ in the vicinity of the on-axis focal position. Thereby, the substantially parallel light can be efficiently focused on the opening Kc of the liquid crystal display device 200 provided at the on-axis focal position. FIG. 7C shows a state in which substantially parallel light substantially parallel to the optical axis OZ is incident on the microlens element 10e. The first surface S1e of the microlens element 10e has a curvature such that the vertex curvature position Te differs from the reference center position Ce by a predetermined distance in a predetermined direction. Light substantially parallel to the optical axis OZ that has entered the microlens element 10e is collected at an off-axis focal position other than on a perpendicular to the second surface S2e passing through the reference center position Ce. For this reason, light is condensed at a position other than the opening Ke of the liquid crystal display device 200, and the light use efficiency is reduced.
[0040]
Next, a case where light is incident on the outer peripheral portion of the microlens array 100 from an oblique direction will be considered. For example, when the microlens element 10c is arranged on the outer peripheral arrangement portion of the microlens array 100, as shown in FIG. 7B, light is incident on the microlens element 10c from an oblique direction. Light incident on the microlens element 10c from an oblique direction is collected near an off-axis focal point other than on a perpendicular to the second surface S2c passing through the reference center position Cc. For this reason, the obliquely incident light is collected at a position other than the opening Kc of the liquid crystal display device 200, and the light use efficiency is reduced. FIG. 7D shows a state in which light enters the microlens element 10e from an oblique direction. The microlens element 10e can efficiently collect light obliquely incident on the position of the opening Ke of the liquid crystal display device 200. As described above, the microlens element 10c having a substantially rotationally symmetric shape with respect to the optical axis OZ is provided at the substantially central position O of the microlens array 100. Further, a microlens element 10 having a shape in which the vertex curvature position T is inflected so as to be different from the reference center position C by a predetermined distance in a predetermined direction is provided on the outer peripheral portion of the microlens array 100. Thereby, the microlens array 100 can efficiently condense the light beam incident on the arrangement position of each microlens element 10 to each opening of the liquid crystal display device 200.
[0041]
Returning to FIG. 6, the five microlens elements 10a to 10e will be described. The five microlens elements 10a to 10e are located at the apex curvature positions so as to determine the curvatures of the first surfaces S1a to S1e of the microlens elements 10a to 10e according to the positions of the microlens elements 10a to 10e in the microlens array 100. Ta to Te are provided. Accordingly, light obliquely incident on the outer peripheral portion of the microlens array 100 and light incident substantially perpendicularly at the center position O can be efficiently condensed at an on-axis focal position on a perpendicular passing through the reference center position. it can. For all the microlens elements 10 on the microlens array 100, a vertex curvature position T suitable for the arrangement position of each microlens element 10 is provided similarly to the five microlens elements 10a to 10e. For example, with respect to the microlens element 10 at a position near a diagonal line of the reference plane 20 of the microlens array 100, the vertex curvature position T is a position shifted obliquely from the reference center position C. Thus, the obliquely incident light can be efficiently collected on the opening. In this manner, the light obliquely incident on the outer peripheral portion of the microlens array 100 and the light incident substantially perpendicularly at the center position O are efficiently condensed at the on-axis focal position on a perpendicular passing through the reference center position C. can do. As a result, according to the distance and direction between the reference center position C of the microlens element 10 and the substantially center position O of the reference plane 20, an effect of efficiently condensing light at the opening of the spatial light modulator can be obtained. Play.
[0042]
The opening of the liquid crystal display device 200 and a region other than the opening will be described. FIG. 12 shows an opening 1200 of the liquid crystal display device 200 and a light shielding area BM other than the opening 1200. The liquid crystal display device 200 has a number of openings 1200 corresponding to the number of pixels. FIG. 12 shows a state in which four openings 1200 are arranged in a row and four openings are arranged in a column in the liquid crystal display device 200 in order to briefly describe the opening and the region other than the opening. Is shown. Further, various wirings, electric elements, and the like are arranged in the shaded area BM indicated by oblique lines in FIG. The microlens element 10 of the microlens array 100 can efficiently collect incident light to the opening 1200. Further, since the light is efficiently condensed on the opening 1200, it is possible to prevent the light from being incident on the light shielding region BM. When light enters the light-blocking region BM, the light is absorbed by the light-blocking region BM, thereby causing a reduction in light use efficiency. Further, as a characteristic of the liquid crystal, the contrast of the projected image increases as the light enters the opening 1200 from a direction closer to the vertical. Therefore, even if the light transmitted through the opening 1200 has many components having a large angle with respect to the optical axis OZ, the contrast of the projected image is reduced. Since the microlens array 100 of the present invention deflects the incident light so as to be substantially parallel to the optical axis OZ, it is possible to prevent the light from being incident on the light shielding area BM and being absorbed, and to reduce the contrast of the projected image. Can be prevented. As a result, there is an effect that a decrease in light use efficiency can be reduced and a projected image of the projector can be made high in contrast.
[0043]
The predetermined position on the reference plane 20 is not limited to the center position O of the reference plane 20, but may be any position on the reference plane 20. A modified example of the present invention will be described using the microlens element 100 shown in FIG. 6A as an example. In the microlens array 100 of the present invention, when a position where the surface Ba substantially parallel to the reference plane 20 and the first surface S1a are in contact with each other is defined as a curvature vertex Pa, the reference center position Ta and the curvature vertex Pa are set on the reference plane 20. Includes a microlens element 10a having a different apex curvature position Ta projected onto the microlens element 10a. The microlens element 10a efficiently collects obliquely incident light at the on-axis focal position by making the reference center position Ca of the microlens element 10a different from the position where the curvature vertex Pa is projected on the reference plane 20. Can be lighted. For example, when the microlens element 10 having the first surface having a substantially rotationally symmetric shape with respect to a perpendicular passing through the reference center position is arranged at the position of the outer peripheral arrangement portion of the reference plane 20, the other microlens elements 10 The position of the curvature vertex Pa is provided differently according to the upper position. Thus, the microlens array 100 capable of efficiently condensing light on the opening or the reflection surface of the liquid crystal display device 200 according to the angular distribution of the incident light incident on the microlens array 100 is obtained.
[0044]
(2nd Embodiment)
Next, a method for manufacturing a microlens element according to the second embodiment of the present invention will be described. FIG. 8 shows a procedure of a method for manufacturing a microlens element according to the second embodiment. First, as shown in FIG. 8A, a resist layer 802 is formed on a substrate 801. Next, a recess having an asymmetric shape is formed in the resist layer 802 on the substrate 801 by a gray scale lithography technique. In the gray scale lithography, for example, a mask can be used in which the photosensitive layer is changed in quality by using a laser beam of a specific wavelength on photosensitive glass, and the light transmittance continuously varies depending on the location. First, a layer in which the light transmittance is continuously changed corresponding to a desired lens shape is formed on the photosensitive glass in the shape of the microlens element 10. The light transmittance of the photosensitive glass decreases due to deterioration. Exposure light is transmitted through this photosensitive glass to expose the resist layer 802. Exposure light is more transmitted in a portion of the photosensitive glass where the change in light transmittance is small. For this reason, the resist layer 802 is more strongly exposed to the exposure light beam transmitted through the layer of the photosensitive glass having a small change in light transmittance. For example, when a positive resist is used, portions exposed more strongly by exposure light are removed by development, and a desired lens shape is formed on the resist layer 802 as shown in FIG. In this manner, a concave portion having the shape of the first surface S1 of the microlens element 10 can be formed in the resist layer 802. Grayscale lithography can use an area gradation mask in addition to using photosensitive glass. The area gradation mask is a method in which the exposure area is varied stepwise according to a desired shape. Even with this method, the shape of the first surface S1 of the microlens element 10 having an asymmetric shape can be formed. According to the gray scale lithography technique, a concave portion having an aspherical shape can be easily formed.
[0045]
Next, in a state where a concave portion having the shape of the first surface S1 of the microlens element 10 is formed in the resist layer 802, CHF ₃ And CF ₄ Dry etching with a fluorine-based gas such as By performing dry etching, the shape of the resist layer 802 can be transferred to the substrate 801. Thereby, as shown in FIG. 8C, a concave portion having the shape of the first surface S1 of the microlens element 10 can be formed on the substrate 801. Next, an optical transparent resin layer 805 is formed on the substrate 801 on which the concave portion having the shape of the first surface S1 of the microlens element 10 is formed. By forming the optically transparent resin layer 805 on the concave portion having the shape of the first surface S1 of the microlens element 10 on the substrate 801, the asymmetric microlens element 10 can be formed. Further, by forming a cover glass 806 on the optically transparent resin layer 805, the microlens array 100 can be obtained.
[0046]
(Third embodiment)
Next, a method for manufacturing a microlens element according to the third embodiment of the present invention will be described. 9 and 10 show a procedure of a method for manufacturing a microlens element according to the third embodiment. First, as shown in FIG. 9A, a resist layer 902 is formed on a substrate 901 by a resist layer forming step. Next, as shown in FIG. 9B, in a first patterning step, the resist layer 902 formed on the substrate 901 by the resist layer forming step is patterned. Next, as in the second embodiment, the resist layer 902 and the substrate 901 are etched by a first etching step which is dry etching. Thereby, as shown in FIG. 9C, a concave portion 910 is formed in the substrate 901. The position of the concave portion 910 formed on the substrate 901 is substantially the same as the position where the resist layer 902 is patterned in the first patterning step.
[0047]
Next, as shown in FIG. 9D, a sacrificial layer 903 having an etching rate different from the etching rate of the substrate 901 is formed on the substrate 901 having the concave portion formed in the first etching step. The sacrificial layer 903 is a film having an etching rate higher than that of the substrate 901, for example, silicon oxide having a higher etching rate than glass. Next, as shown in FIG. 9E, a mask layer 904 is formed on the sacrificial layer 903 by a mask layer forming step. This mask layer 904 is formed of, for example, polysilicon, chromium, or an alloy thereof. Further, as shown in FIG. 9F, the mask layer 904 is patterned at a position different from the concave portion 910 of the substrate 901 by the same photolithography, dry etching, or laser processing as described above. Thus, a mask layer 904 that is patterned at a position different from the concave portion 910 of the substrate 901 is formed on the sacrificial layer 903. Here, the “different position” means that the position of the penetrating portion 911 formed in the mask layer 904 by patterning and the position of the concave portion 910 of the substrate 901 are different positions when each is projected on a horizontal plane. I do.
[0048]
Next, as shown in FIG. 10A, the sacrifice layer 903 and the substrate 901 are etched in a second etching step. The etching is performed through the penetrating portion 911 formed in the mask layer 904. First, the sacrificial layer 903 is etched substantially concentrically around the penetrating portion 911 of the mask layer 904. When the etching progresses to the substrate 901, the substrate 901 is also etched around a position substantially perpendicular to the penetrating portion 911 of the mask layer 904. At this time, since the etching rate of the sacrificial layer 903 is higher than that of the substrate 901, the etching rate of the substrate 901 is lower than that of the sacrificial layer 903. Here, the inside of the concave portion 910 of the substrate 901 is a sacrificial layer 903 having an etching rate different from that of the substrate 901. Therefore, when the location where the etching proceeds reaches the concave portion 910 of the substrate 901, the concave portion 910 of the substrate 901 is etched quickly. Since the concave portion 910 is etched earlier, the center position of the progress of the etching is shifted toward the concave portion 910 of the substrate 901. In this way, by making the center position of the etching progress position different from the position of the penetrating portion 911 of the mask layer 904, a concave portion 912 having an asymmetric shape is formed on the substrate 901 as shown in FIG. Can be. Further, as shown in FIG. 10C, only the substrate 901 in which the asymmetric concave portion 912 is formed by the process of removing the mask layer 904 and the sacrificial layer 903 is obtained. The mask layer 904 and the sacrificial layer 903 can be removed by wet etching with a hydrofluoric acid solution. Thereafter, as shown in FIG. 10D, an optical transparent resin layer 905 is formed on the asymmetrical concave portion 912 formed on the substrate 901. By forming the optically transparent resin layer 905 on the asymmetric recess 912 on the substrate 901, the asymmetric microlens element 10 of the present invention can be formed. Further, by forming a cover glass 906 on the optically transparent resin layer 905, the microlens array 100 can be obtained.
[0049]
When the position of the through portion 911 on the mask layer 904 is changed with respect to the position of the concave portion 910 of the substrate 901, the direction of the vertex curvature position T with respect to the reference center position C is different from the first surface S 1 of the microlens element 10. Such a curvature can be obtained. When the horizontal distance between the position of the concave portion 910 of the substrate 901 and the position of the penetrating portion 911 of the mask layer 904 is changed, the reference center position C, the vertex curvature position T, and the first surface S1 of the microlens element 10 are changed. Can be curved so that the distance between the two is different. Therefore, by setting the position of the concave portion 910 of the substrate 901 and the position of the penetrating portion 911 on the mask layer 904 in a predetermined direction and a predetermined distance, the vertex curvature position T of the microlens element 10 can be changed to the reference center position C From a predetermined distance in a predetermined direction. This allows the vertex curvature position T of the microlens element 10 to be a position on the reference plane 20 of the microlens array 100 that has a curvature corresponding to the position of the microlens element 10. The direction and distance between the position of the concave portion 910 of the substrate 901 and the position of the through portion 911 on the mask layer 904 can be set for each microlens element 10 to be manufactured. Thereby, the above-described microlens array 100 can be obtained. In the manufacturing method of the present embodiment, the direction and distance between the position of the concave portion 910 of the substrate 901 and the position of the through portion 911 of the mask layer 904 are changed. However, the invention is not limited thereto, and the recess 910 of the substrate 901 may be shallower and have a larger area without providing the sacrificial layer 903. Also in this case, similarly to the above-described manufacturing method, by etching after patterning so that the center position of the penetrating portion 911 of the mask layer 904 and the center position of the concave portion 910 are different, the apex curvature position T of the microlens element 10 is obtained. Can be changed. Further, the sacrificial layer 903 may not be provided, and a plurality of recesses 910 may be provided in the shape of the first surface S1 of the microlens element 10. In this case, the apex curvature position T of the microlens element 10 can be changed by changing the number and position of the concave portions 910 and performing etching.
[0050]
(Fourth embodiment)
FIG. 11 shows a schematic configuration of a projector according to a fourth embodiment of the invention. In the projector 1100 of the present embodiment, the microlens array 100 is provided on each of the three liquid crystal display devices on the light incident side. The lighting device 1110 includes a light source unit 1111 that supplies light and a reflector 1112. For the light source portion 1111, an ultra-high pressure mercury lamp can be used. The light source unit 1111 supplies light including R light that is a first color light, G light that is a second color light, and B light that is a third color light. Light from the light source unit 1111 is emitted directly or by reflecting off the reflector 1112. The light from the light source 1111 is made substantially parallel to the principal ray by an illumination optical system (not shown), and then enters the fly-eye integrator 1120. The fly-eye integrator 1120 equalizes the illuminance distribution of the light from the illumination device 1110. The configuration of the fly-eye integrator 1120 for making the illuminance distribution of light uniform is the same as the configuration of the fly-eye integrator 310 described with reference to FIG.
[0051]
The light whose illuminance distribution has been made uniform by the fly-eye integrator 1120 is converted by the polarization conversion element 1130 into polarized light having a specific vibration direction, for example, s-polarized light. The light converted into the s-polarized light is incident on the R light transmitting dichroic mirror 1140R constituting the color separation optical system. Hereinafter, the R light will be described. The R light transmitting dichroic mirror 1140R transmits the R light and reflects the G light and the B light. The R light transmitted through the R light transmitting dichroic mirror 1140R enters the reflection mirror 1145. The reflection mirror 1145 bends the optical path of the R light by 90 degrees. The R light whose optical path is bent enters the R lens microlens array 100R. The microlens array for R light 100R is the same as the microlens array 100 described in the first embodiment. The R light emitted from the R lens microlens array 100R enters the R light liquid crystal display device 110R. The R light liquid crystal display device 1150R is a transmissive liquid crystal display device that modulates R light according to an image signal. Since the polarization direction of the light does not change even when the light passes through the dichroic mirror, the R light incident on the R light liquid crystal display device 1150R remains in the s-polarized light state. The s-polarized light incident on the R-light liquid crystal display device 1150R is converted to p-polarized light, and then converted to s-polarized light by modulation according to an image signal. The R light converted into the s-polarized light by the modulation enters a cross dichroic prism 1160 which is a color combining optical system.
[0052]
Next, the G light will be described. The light paths of the G light and the B light reflected by the R light transmitting dichroic mirror 1140R are bent by 90 degrees. The G light and the B light whose optical paths are bent enter the B light transmitting dichroic mirror 1140B. The B light transmitting dichroic mirror 1140B reflects the G light and transmits the B light. The G light reflected by the B light transmitting dichroic mirror 1140B enters the G light microlens array 100G. The microlens array 100G for G light is the same as the microlens array 100 described in the first embodiment. The R light emitted from the G light microlens array 100G enters the G light spatial light modulator 1150G. The G light spatial light modulator 1150G is a transmissive liquid crystal display device that modulates G light according to an image signal. The G light incident on the G light spatial light modulator 1150G has been converted into s-polarized light. The s-polarized light that has entered the spatial light modulator for G light 1150G is converted into p-polarized light by modulation according to the image signal. The G light converted into p-polarized light by the modulation enters a cross dichroic prism 1160 which is a color combining optical system.
[0053]
Next, the B light will be described. The B light transmitted through the B light transmitting dichroic mirror 1140B is incident on the B light microlens array 100B via two relay lenses 1142 and 1143 and two reflection mirrors 1146 and 1147. The microlens array 100B for B light is the same as the microlens array 100 described in the first embodiment. The B light emitted from the B light microlens array 100B enters the B light spatial light modulator 1150B. The B light liquid crystal display device 1150B is a transmissive liquid crystal display device that modulates the B light according to an image signal.
[0054]
The reason why the B light passes through the two relay lenses 1142 and 1143 is that the optical path of the B light is longer than the optical paths of the R light and the G light. By using the two relay lenses 1142 and 1143, the B light transmitted through the B light transmitting dichroic mirror 1150B can be directly guided to the B light liquid crystal display device 1150B. The B light incident on the B light liquid crystal display device 1150B has been converted into s-polarized light. The s-polarized light incident on the B light liquid crystal display device 110B is converted to p-polarized light, and then converted to s-polarized light by modulation according to an image signal. The B light modulated by the B light liquid crystal display device 1150B enters a cross dichroic prism 1160 which is a color combining optical system.
[0055]
The cross dichroic prism 1160, which is a color synthesizing optical system, is configured by arranging two dichroic films 1161 and 1162 orthogonally in an X-shape. The dichroic film 1161 reflects B light and transmits R light and G light. The dichroic film 1162 reflects R light and transmits B light and G light. As described above, the cross dichroic prism 112 combines the R light, the G light, and the B light modulated by the R light liquid crystal display device 1150R, the G light liquid crystal display device 1150G, and the B light liquid crystal display device 1150B. The projection lens 1170 projects the light combined by the cross dichroic prism 1160 on a screen 1180.
[0056]
As described above, light incident on the cross dichroic prism 1160 from the R light liquid crystal display device 1150R and the B light liquid crystal display device 1150B is set to be s-polarized light. Further, light incident on the cross dichroic prism 1160 from the liquid crystal display device for G light 1150G is set to be p-polarized light. The reason why the polarization direction of the light incident on the cross dichroic prism 1160 is made different is that the light emitted from each color light liquid crystal display device is effectively combined in the cross dichroic prism 1160. The dichroic films 1161 and 1162 generally have excellent s-polarized light reflection characteristics. Therefore, R light and B light to be reflected by the dichroic films 1161 and 1162 are s-polarized light, and G light to be transmitted through the dichroic films 1161 and 1162 is p-polarized light.
[0057]
Microlens arrays 100R, 100G, and 100B are provided on the incident side of each color light liquid crystal display device of the projector 1100. Each of the microlens arrays 100R, 100G, and 100B is the same as the microlens array described in the first embodiment. Therefore, each of the microlens arrays 100R, 100G, and 100B can efficiently condense the light having the highest intensity among the incident lights to the openings of the liquid crystal display devices 1150R, 1150G, and 1150B. Thereby, there is an effect that the light use efficiency of the projector 1100 can be improved.
[0058]
The fly-eye integrator 1120 arranges the image of the light source unit 1111 on a plane with the same number of light sources as the number of small lenses included in each lens array. Then, light from the plurality of light sources is superimposed on each microlens element 10 of the microlens array 100. For this reason, the number of small lenses in the lens array of the fly-eye integrator 1120, the irradiation area area of the micro-lens array 100 with respect to the area of the exit side of the fly-eye integrator 1120, the distance between the fly-eye integrator and the micro-lens array 100, etc. Changes the shape of each microlens element 10. By changing the shape of each microlens element 10 in this manner, the light use efficiency can be further improved.
[0059]
In the present embodiment, an example in which the microlens array 100 of the present invention is used for a transmissive liquid crystal display device has been described, but a spatial light modulator in which the microlens array 100 of the present invention can be provided is a transmissive liquid crystal display device. It is not limited to the device. For example, the microlens array 100 of the present invention may be provided in a reflective liquid crystal display device or a tilt mirror device. One example of a tilt mirror device is the Texas Instruments Digital Micro Mirror Device (DMD). For example, the microlens array 100 of the present invention is provided on the incident side of the DMD. The DMD has a movable mirror element as a spatial light modulation element. The first surface S1 of each microlens element 10 has a curvature such that light of high intensity among incident light is focused on the reflection surface of the movable mirror element. The microlens array 100 of the present invention provided on the incident side of the DMD in this way can be efficiently moved in a substantially parallel light state, similarly to the microlens array 100 of the present invention provided on the incident side of the transmission type liquid crystal display device. Light can be collected on the reflection surface of the mirror element. In this way, by making the light beams substantially parallel to the optical axis on all of the spatial light modulation elements, kicking in the front optical system can be prevented, and a highly efficient display device such as a projector can be realized.
[0060]
Further, in the projector 1100 of the present invention, the incident light on the microlens array 100 is made uniform in the illuminance distribution by the fly-eye integrator 1120. The reason why the microlens array 100 efficiently condenses the incident light on the opening or the reflecting surface of the spatial light modulator is not limited to the case where the fly-eye integrator 1120 makes the illuminance distribution uniform. The microlens array 100 is not limited to the case where the light from the light source unit is made uniform by the fly-eye integrator and the case where the light from the light source unit is incident on the spatial light modulator. Of the microlens element 10 can be used. For example, when the light from the light source unit is made uniform by the rod integrator, the spatial light modulator is generally illuminated at approximately the same magnification with the light from the light source unit. At this time, light from the light source unit is applied to a portion other than the outer edge of the spatial light modulator from a substantially uniform direction. The outer edge of the spatial light modulator is irradiated mainly with light in an oblique direction. Therefore, by using the microlens element 10 of the first embodiment on the outer edge of the spatial light modulator, the obliquely incident light can be efficiently condensed on the opening or the reflecting surface of the spatial light modulator. it can.
[0061]
Further, the microlens array 100 may be provided even when a solid-state light-emitting element such as a light-emitting diode element (LED) or an electroluminescent (EL) is used as a light source section, or when a solid-state laser element is used. it can. For example, when an LED is used for the light source unit, a plurality of LEDs can be used. In the case where a solid-state laser element is used for the light source section, a configuration in which laser beams from a plurality of solid-state laser elements are bundled can be employed. At this time, by controlling the angle at which each LED or laser beam is incident on the spatial light modulator by the microlens element 10 of the microlens array 100, the light from the light source unit is controlled similarly to the projector 1100 of the present embodiment. It can be used efficiently. Further, the microlens array 100 is not limited to a projector, and can be applied to a light receiving element such as a CCD camera or a C-MOS sensor. FIG. 13 shows a state in which the microlens array 1300 according to the first embodiment is used as a light receiving element. The micro lens array 1300 is provided on the incident side of the light receiving element 1340. The plurality of microlens elements 1310 are arranged in the cover glass 1330 with the convex surface facing the incident side of the incident light L. The microlens element 1310 can efficiently collect light obliquely incident on the light receiving surface 1320 of the light receiving element 1340. The microlens element 1310 of the microlens array 1300 efficiently collects incident light on the light receiving surface 1320 of the light receiving element 1340, so that a high-sensitivity image can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a microlens array according to a first embodiment.
FIG. 2 is a diagram showing a cross section of a microlens array.
FIG. 3 is a diagram illustrating a state in which light irradiates a microlens array.
FIG. 4 is a diagram showing a distribution of an incident angle of incident light.
FIG. 5 is a diagram illustrating a difference in distribution of incident angles.
FIG. 6 is a diagram showing a cross section of each microlens element.
FIG. 7 is a diagram showing a state in which a microlens element condenses incident light.
FIG. 8 is a diagram showing a procedure of a method for manufacturing a microlens array.
FIG. 9 is a diagram showing a procedure of a method for manufacturing a microlens array.
FIG. 10 is a diagram showing a procedure of a method for manufacturing a microlens array.
FIG. 11 is a diagram showing a schematic configuration of a projector according to a fourth embodiment.
FIG. 12 is a diagram showing an opening and a portion other than the opening of the liquid crystal display device.
FIG. 13 is a diagram showing a state in which a microlens array is used for a light receiving element.
[Explanation of symbols]
10, 10a to e micro lens element, 20 reference plane, 100, 100R, 100G, 100B micro lens array, 200 liquid crystal display device, 300 lighting device, 301 light source unit, 302 reflector, 310 fly-eye integrator, 311 and 312 lens Array, 801, 901 substrate, 802, 902 resist layer, 805, 905 optically transparent resin layer, 806, 906 cover glass, 903 sacrificial layer, 904 mask layer, 910, 912 recess, 911 penetration, 1100 projector, 1110 illumination Apparatus, 1111 light source unit, 1112 reflector, 1120 fly-eye integrator, 1130 polarization conversion element, 1140R, 1140B dichroic mirror, 1142, 1143 relay lens, 1145, 1146 reflection mirror, 1 150R, 1150G, 1150B Liquid crystal display device, 1160 cross dichroic prism, 1161, 1162 dichroic film, 1170 projection lens, 1180 screen, 1200 opening, 1300 micro lens array, 1310 micro lens element, 1320 light receiving surface, 1330 cover glass, 1340 Light receiving element, OZ optical axis, Ba plane, C, Ca to Ce reference center position, D1a, D1b, D2a, D2b distance, Ka to Ke opening, O center position, S1, S1a to S1e First surface, S2, S2a ~ S2e Second surface, T, Ta ~ Te Vertex curvature position

Claims (8)

A microlens array provided on a light incident side of incident light and having a plurality of microlens elements including a first surface having a curvature and a substantially planar second surface through which the incident light incident on the first surface is transmitted. And
The plurality of microlens elements are arranged on a reference plane having a predetermined area, and a position of substantially the center of the area of the second surface of the microlens element is set as a reference center position,
A position where a contact point between the plane contacting the first surface and the first surface is projected onto the reference plane when the plane contacting the first surface of the microlens element is substantially parallel to the reference plane. Is the vertex curvature position,
The first surface has the curvature such that the reference center position and the vertex curvature position differ by a predetermined distance in a predetermined direction according to the reference center position of the microlens element on the reference plane. Characterized micro lens array. The distance between the reference center position of the microlens element and a predetermined position on the reference plane, the reference center position of the microlens element, and the vertex curvature position of the microlens element. The microlens array according to claim 1, wherein the predetermined distance is substantially proportional. The orientation of a predetermined position on the reference plane with respect to the reference center position of the microlens element is the same as the orientation of the vertex curvature position of the microlens element with respect to the reference center position of the microlens element. The microlens array according to claim 2, wherein The microlens array according to any one of claims 1 to 3, wherein the plurality of microlens elements are arranged in a substantially orthogonal lattice shape on the reference plane. A microlens array in which a plurality of microlens elements having a function of deflecting light are arranged on a reference plane,
The microlens element includes a first surface having a curvature, and a substantially planar second surface through which light incident on the first surface is transmitted.
The position of the approximate center of each of the regions of the second surface of the microlens element is defined as a reference center position,
When the position where the surface substantially parallel to the reference plane and the first surface are in contact with each other is defined as a curvature vertex,
A microlens array comprising a microlens element having a different reference center position and a different position at which the curvature vertex is projected on the reference plane. A resist layer forming step of forming a resist layer on the substrate,
A first patterning step of patterning the resist layer;
A first etching step of pre-etching the resist layer and the substrate, and a mask layer forming step of forming a mask layer on the substrate pre-etched by the first etching step;
A second patterning step of patterning the mask layer formed by the mask layer forming step;
A second etching step of etching the substrate through the pattern formed by the second patterning step,
A method for manufacturing a microlens array, wherein a center position of a pattern formed by the first patterning step is different from a center position of a pattern formed by the second patterning step. The microlens array according to any one of claims 1 to 5, which collects the incident light,
Having a spatial modulation element that modulates the incident light collected by the microlens array,
The spatial light modulator, wherein the microlens array is arranged on the incident side of the incident light of the spatial light modulator. A light source unit for supplying light,
A spatial light modulator that modulates light from the light source unit according to an image signal,
And a projection lens that projects light modulated by the spatial light modulator,
A projector, wherein the spatial light modulator is the spatial light modulator according to claim 7.

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