JP3958085B2 - Image display apparatus and image projection apparatus using microlens array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image display device and an image projection device using a microlens array.
[0002]
[Prior art]
Projectors that display video images, computer output images, and the like are widely used. In recent years, the development of projectors has been progressing with the aim of high-definition images, high illuminance, miniaturization of devices, and cost reduction.
[0003]
The reduction in pixel size on the light valve has been pursued with the aim of increasing the definition of the image, but as the pixel size is reduced, the area occupied by the wiring other than the pixels (black matrix) is relative. However, there is a problem that the aperture ratio is lowered, the projected image becomes dark, and the image quality is deteriorated.
[0004]
In order to solve this problem, it has been proposed to arrange a microlens corresponding to each pixel on the light valve and improve the aperture ratio by using the condensing by the microlens (Japanese Patent No. 3110652, which No. 2000-19307). In this case, it is important to collect incident light efficiently on the pixel of the light valve by the microlens and to facilitate manufacture when the microlens array and the spatial light modulator are integrated.
[0005]
In the image display device described in each of the above publications, a “single microlens array” is used, and light is focused on each pixel on a single microlens surface. If the radius of curvature of the lens is reduced, the spherical aberration deteriorates and noise components to adjacent pixels increase, and if the radius of curvature is increased, the focusing power is weakened and the effect of increasing the aperture efficiency cannot be obtained sufficiently. is there.
[0006]
As a method for solving such a problem, Japanese Patent Application Laid-Open No. 2000-305472 discloses a method of using two microlens arrays to efficiently collect light on each pixel.
[0007]
However, the image display device described in this publication is “from the light incident side, transparent substrate, second microlens, second adhesive, second cover glass, gel adhesive, first microlens, first microlens, 1 adhesive material, 1st cover glass is provided, and this 1st cover glass and the light valve are united ", and since the whole is a multi-layer structure, the number of used members and the number of manufacturing processes are many. However, it is not always easy, and it is hard to say that the cost is sufficiently low.
[0008]
[Problems to be solved by the invention]
The present invention is a combination of two microlens arrays and a spatial light modulator, has a high light collection efficiency to each pixel of the spatial light modulator, and has a simple structure and is easy to manufacture. An object is to provide a novel image display device that can be realized at low cost.
[0009]
Another object of the present invention is to provide a novel image projection device using the image display device.
[0010]
[Means for Solving the Problems]
The image display device of the present invention includes a spatial light modulation element, a first microlens array, and a second microlens array.
The “spatial light modulator” spatially modulates the intensity of transmitted light or reflected light. As the spatial light modulation element, a conventionally known transmissive or reflective liquid crystal light valve can be used.
[0011]
In the “first microlens array and second microlens array”, the lens arrangement of the microlenses in each of them corresponds to the pixel arrangement in the spatial light modulator. Here, “corresponds to the lens arrangement of the microlens and the pixel arrangement that can be placed on the spatial light modulation element” means that the arrangement of the microlens array is adjusted by adjusting the position of the microlens array with respect to the spatial light modulation element. It means that it can be overlapped with the array.
[0012]
The first and second microlens arrays are opposed to each other with a “predetermined gap”, and are close to or in close contact with the first microlens array on the side opposite to the second microlens array via the first microlens array. Thus, a spatial light modulation element is arranged. That is, the spatial light modulation element, the first and second microlens arrays are arranged in this order.
[0013]
Light to be incident on the spatial light modulation element is incident from the second microlens array side, and is condensed on each pixel of the spatial light modulation element by the microlenses of the first and second microlens arrays.
[0014]
Thus, since incident light is condensed on a pixel by each microlens of two microlens arrays, the condensing power of each microlens can be set without difficulty to such an extent that “spherical aberration is not deteriorated”.
[0015]
As described above, since the first and second microlens arrays are opposed to each other with a predetermined gap therebetween, there is a “predetermined gap” between them. The predetermined gap portion may be an air layer or may be “filled with resin” (claim 2). As described above, when the space between the first and second microlens arrays is filled with resin, the radius of curvature or the focal length of the microlens is adjusted by adjusting the relationship between the refractive index of the filling resin and each microlens array material. Therefore, the degree of freedom of design with respect to the refractive power of each microlens is increased, and the manufacture of each microlens array is facilitated.
[0016]
  The image display apparatus according to claim 1 is characterized by the following points.
  That is, “one of the first microlens array and the second microlens array is shifted from the other by a half pitch in the microlens array pitch in at least one direction”.
The pitch of the lens array in the first and second microlens arrays is equal to the pitch of the pixel array in the spatial light modulator.
  Since the microlens array pitch in the first and second microlens arrays is shifted by at least a half pitch in one direction, the lens layout of one microlens array overlaps the pixel layout, but the lens layout of the other microlens array is The lens arrangement is shifted by a half pitch in at least one of the vertical and horizontal directions of the lens arrangement.
  Accordingly, the first microlens array and the second microlens arrayAmong them, any one microlens in one microlens array, and at least two microlenses shifted by a half pitch in at least one direction with respect to the one microlens in the other microlens array, spaceThe light is condensed on each pixel of the light modulation element.
[0017]
  3. The image display device according to claim 1, wherein the microlenses of the first microlens array can have a convex shape, and the microlenses of the second microlens array can have a concave shape.(Claim 3)On the other hand, the microlenses of the first microlens array can be concave, and the microlenses of the second microlens array can be convex.
[0018]
  the aboveClaims 1-4At least one of the first and second microlens arrays in the image display device according to any one of the above may be a “structure having a gap between microlenses” (Claim 5),Claims 1-5At least one of the first and second microlens arrays in the image display device according to any one of the above may be “a structure in which the arrangement of microlenses is dense” (Claim 6).
[0019]
  Claims above1-6The image display device according to any one of the above may include a spacer that maintains and / or adjusts the gap and / or position between the first and second microlens arrays (Claim 7).
[0020]
  The image projection apparatus of this invention has the image display apparatus of any one of Claims 1-7, a light source, and a projection lens (Claim 8).
[0021]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments will be described.
  FIG. 1A shows an image display device.Reference exampleIs schematically illustrated.
  Reference numeral 1 denotes a first microlens array, reference numeral 3 denotes a second microlens array, and reference numeral 4 denotes a spatial light modulator.
[0022]
  This exampleThe spatial light modulator 4 is a reflective “liquid crystal light valve”, and spatially modulates the intensity of the reflected light. In the first microlens 1 and the second microlens array 3, microlenses are arrayed at the same pitch as the pixel array placed on the spatial light modulator 4, and from the direction of the direction 200 orthogonal to the pixel surface of the spatial light modulator 4. As seen, the positional relationship between the first and second microlens arrays is determined so that the arrangement of the microlenses overlaps the pixel arrangement.
[0023]
The first and second microlens arrays 1 and 3 are separated from each other by a predetermined gap 2 and are opposed to each other through the first microlens array 1. The spatial light modulator 4 is arranged in close contact with the first microlens array 1. The gap 2 is an “air layer”. The whole is integrated by appropriate means.
[0024]
The light 5 to be incident on the spatial light modulation element 4 is incident from the second microlens array 3 side, and each pixel of the spatial light modulation element 4 is formed by the microlenses of the first and second microlens arrays 1 and 3. It is focused on.
[0025]
In FIG. 1B, the symbol PC indicates one of the pixels in the spatial light modulator 4, and the symbol 6 indicates a light spot condensed on the pixel PC. At this time, when the size of the light spot 6 condensed on the pixel PC is “a little smaller than the pixel size”, the spot image is smaller than the pixel on the screen when reflected by the pixel PC and emitted. Therefore, the projected image is “high definition image”.
[0026]
As described above, the spatial light modulation element in the image display apparatus shown above is a reflective liquid crystal light valve. As such a liquid crystal light valve, LCOS (Liquid Crystal on Si) is known. Of course, a “transmissive liquid crystal light valve” can also be used as the spatial light modulator.
[0027]
  That is, the image display apparatus of FIG.(Reference example)Includes a spatial light modulation element 4 that spatially modulates the intensity of reflected light, and first and second microlens arrays 1 and 3, and the lens arrangement in the first and second microlens arrays 1 and 3 is spatial light. Corresponding to the pixel arrangement in the modulation element 4, the first and second microlens arrays 1, 3 are opposed to each other with a predetermined gap 2, and the second microlens array 3 is interposed via the first microlens array 1. On the opposite side, a spatial light modulation element 4 is arranged in close contact with the first microlens array 1, and light incident from the second microlens array 3 side is transmitted to the first and second microlens arrays 1, 3. So that each microlens can focus on each pixel of the spatial light modulator 4Is composed.
[0028]
The material of the first and second microlens arrays 1 and 3 can be mineral or resin, but glass is generally used. Considering the dry etching process for forming the microlens array, “alkali-free or low alkali glass” is preferable. A typical example is quartz glass (n (refractive index, hereinafter the same) = 1.46).
[0029]
When the gap 2 is filled with the resin, as described above, the curvature radius and the focal length of the microlens are adjusted by adjusting the relationship between the refractive index of the filled resin and the refractive index of the material of the microlens arrays 1 and 3. Thus, the degree of freedom in design with respect to the refractive power of each microlens increases, and the manufacture of each microlens array becomes easy.
[0030]
In such a case, quartz glass as a microlens array material has a difference in refractive index and linear expansion coefficient between the resin and the microlens array material (if the thermal expansion coefficient differs greatly, the manufacturing process includes a heating process) In view of cost reduction and the like, there is a problem that the microlens array and the resin are peeled off due to thermal stress), 1737 (n = 1.52) manufactured by Corning, and Neoceram N-0 manufactured by Nippon Electric Glass (N = 1.541) and the like are preferable.
[0031]
As the resin filled in the gap between the first and second microlens arrays, an ultraviolet curable resin is preferable, and an acrylic resin having a refractive index of 1.40 to 1.70 (for example, manufactured by NTT Advanced Technology) is used. These are known and can be appropriately selected and used.
[0032]
When producing a microlens array, a glass substrate with a thickness of about 1 mm is often used. Even after the lens is formed by dry etching, the thickness is about this. Such a microlens array is commercially available (for example, manufactured by MEMSOPTICAL, pitch 15 μm to 500 μm, lens shape, circular, square, etc., substrate: quartz glass).
[0033]
The thickness of 1 mm is to ensure the strength of the substrate, but it can be reduced to several tens of μm by polishing, and it is a matter of course that a thin microlens array can be produced.
[0034]
As shown in FIG. 1, the configuration in which “the first and second microlens arrays 1 and 3 are arranged with the gap 2 interposed therebetween and the spatial light modulator 4 is in close contact with the first microlens 1 and integrated as a whole” is simple. Therefore, since the number of members is small, the number of manufacturing steps is small, and it can be manufactured easily and inexpensively. In addition, since two microlens arrays are used, the condensing efficiency of each microlens can be set easily, incident light can be efficiently focused on the pixel, and noise light to adjacent pixels can be reduced. .
[0035]
When the light is collected by the microlens array, a light intensity distribution is generated on each pixel, and when this is viewed two-dimensionally, a profile as shown in FIG. 8 is obtained. If the base of this profile is within one pixel, there is no noise light to adjacent pixels. Further, as the profile is “thinner”, the projected image is a “high-definition image”.
[0036]
As an index of the high-definition image, the half-value width: HV of the profile of the light intensity distribution is used. Half width of profile: The smaller the HV, the higher the definition. On the other hand, light utilization efficiency is also important as performance. “Light utilization efficiency” is determined by how light passing through one microlens is collected on a corresponding pixel without loss.
[0037]
The profile shown in FIG. 8 has a “skirt slightly extending to adjacent pixels”, resulting in a slight loss of light utilization efficiency. This loss light component is “noise light” when viewed from adjacent pixels, and causes deterioration in image quality of the projected image.
[0038]
Numerical examples are shown below.
The first and second comparative numerical examples 1 and 2 are examples when one microlens array is used. That is, the microlens array is arranged close to the pixel surface of the spatial light modulator so that the microlens is on the pixel side, the microlens array overlaps the pixel array, and the gap between the two is made of a transparent resin. It has a filled configuration.
[0039]
Comparative numerical example 1
Pixel size: 14 μm square (refers to a square shape with a side of 14 μm; the same applies hereinafter)
Refractive index of resin filled in gap: 1.4
Micro lens array
Refractive index: 1.52 Radius of curvature of micro lens (convex): 7 μm
Distance from microlens tip to pixel (gap filled with resin): 30 μm
Half-value width of light intensity distribution profile of light condensed on pixel: 5.1 μm
Light utilization efficiency: 65%
In the case of this comparative numerical example 1, the curvature radius of each microlens in the microlens array is as small as 7 μm, and the condensing property of incident light is high. The half width of the profile is as small as 5.1 μm, and the profile is sharp, but the spherical aberration of the microlens is large, there is a lot of “noise light” going to the adjacent pixels, the light loss is large, and the light utilization efficiency is as low as 65% .
[0040]
Numerical comparison example 2
Pixel size: 14μm square
Refractive index of resin filled in gap: 1.4
Micro lens array
Refractive index: 1.52 Micro lens (convex) radius of curvature: 10 μm
Distance from microlens tip to pixel (gap filled with resin): 30 μm
Half-value width of light intensity distribution profile of light condensed on pixel: 8.6 μm
Light use efficiency: 95%
In comparative numerical example 2, since the radius of curvature of the microlens is large and the spherical aberration is small, the light is collected on the pixel, the light loss is small, and the light utilization efficiency is high. The half width of the profile is large and the profile is broad, but even if the half width is large, it is 61% compared to the pixel size, and compared with Comparative Numerical Example 1 in terms of high definition of the projected image. Although it is slightly inferior, if the light utilization efficiency is the same and the half-value width is less than this, it can be said that the configuration is excellent.
[0041]
  Numerical examples of reference examples
  Specific examples relating to the embodiment described above will be given below.
  Numerical example 1
  Pixel size: 14μm square
  Gap between microlenses: Air layer (refractive index: 1)
  First micro lens array
  Refractive index 1.52 Micro lens (convex) radius of curvature: 10 μm
  Thickness of the first microlens array (distance from the tip of the microlens to the surface of the spatial light modulation element in close contact with the first microlens array. The same applies to each of the following embodiments): 30 μm
  Second micro lens array
  Refractive index 1.52 Micro lens (convex) radius of curvature: 20 μm
  Gap between microlens arrays (from the tip of the lens to the tip): 3 μm
  Half width of profile: 7.6 μm
  Light utilization efficiency: 100%
  Numerical example 2
  Numerical example 2These are examples when the gap between the microlenses is filled with a member having a refractive index of 1.4. In this example, it can be seen that the full width at half maximum is smaller than when the gap is an air layer.
[0042]
  Pixel size: 14μm
  Refractive index of resin filled in gaps between microlenses: 1.4
  First micro lens array
  Refractive index 1.52 Micro lens (convex) radius of curvature 20μm
  Thickness of the first microlens array: 30 μm
  Second micro lens array
  Refractive index: 1.52 Micro lens (convex) radius of curvature: 10 μm
  Gap between microlens arrays (from the tip of the lens to the tip): 3 μm
  Half width of profile: 6.2 μm
  Light utilization efficiency: 97%
  Numerical examplesBoth 1 and 2 have a narrower half-width of the profile and higher light utilization efficiency than Comparative Numerical Examples 1 and 2. That is, in the first and second embodiments, a high-definition and bright projection image can be realized.
[0043]
  FIG. 2 illustrates one embodiment of the image display device in an explanatory manner.
  As shown in FIG. 2A, the image display device includes a spatial light modulation element 4a that spatially modulates the intensity of transmitted light or reflected light, and first and second microlens arrays 1a and 3a. The lens arrangement in the first and second microlens arrays corresponds to the pixel arrangement in the spatial light modulator 4a, and the first and second microlens arrays 1a and 3a are opposed to each other with a predetermined gap 2a therebetween. Light that is incident on the side of the second microlens array 3a is arranged on the side opposite to the second microlens array 3a via the lens array 1a, and a spatial light modulation element 4a is disposed in close contact with the first microlens array 1a. Is condensed on each pixel of the spatial light modulation element 4a by each microlens of the first and second microlens arrays.It is composed.The whole is integrated by an appropriate means.
[0044]
The arrangement of the microlenses in the first microlens array 1a overlaps the pixel arrangement in the spatial light modulation element 4a when viewed from the optical axis direction, but the arrangement pitch of the microlenses in the second microlens 3a is The microlens array 1a is shifted in one direction (left-right direction in the figure) by a half pitch with respect to the arrangement pitch of the microlenses in the microlens array 1a.
[0045]
In this way, incident light is first collected by the second microlens array 3a, and then collected by the first microlens array 1a (in a region within 1/2 of each microlens) via the gap 2a. When the radius of curvature of the microlenses of the second microlens array 3a is small and close to a hemispherical shape, the spherical aberration becomes large. On the contrary, when the radius of curvature is large, the light bending force is weak and there is a problem that light cannot be collected efficiently. This tendency is particularly remarkable around the lens.
[0046]
  The second microlens array 3aFirstIf the microlens 1a is shifted from the microlens 1a, as shown in FIG. 2B, the light 5a that has passed through the periphery of the microlens L3a of the second microlens array is converted into the microlens L1a in the first microlens array 1a. The light passes through the vicinity of the center of the light and can be efficiently condensed on the pixel.
  Also, for example, when the radius of curvature of the microlens L3a of the second microlens array is small with respect to the pixel size, and there are gaps at the four corners in the diagonal direction of the pixels, the light passing through these four corners travels substantially straight, If there is no “shift” in the first and second microlens arrays, light is not collected at the pixel center.
[0047]
However, when the second microlens array 3a is shifted from the first microlens array 1a as shown in FIG. 2, the “substantially straight light” passes through the microlens of the first microlens 1a and passes over the pixel. Is effectively condensed.
[0048]
In addition, when a light shielding layer (black matrix) is provided in an actual liquid crystal light valve, the light traveling substantially straight is shielded by the light shielding layer, which does not lead to deterioration of the image, but the light use efficiency decreases.
[0049]
The above shows the case where the microlenses in the first and second microlens arrays are convex, but when the resin is filled in the gap between the first and second microlens arrays, the refractive index of the resin: n2 Depending on the magnitude relationship between the refractive index of the material of the first microlens array: n1 and the refractive index of the material of the second microlens array: n3, the shape of the microlens in each microlens array may be a convex shape. It is also possible to do.
[0050]
In other words, when both the first and second microlens arrays have convex shapes, it is sufficient that n3> n1> n2, n1 = n3> n2 or n1> n3> n2 is satisfied. In the case of the concave shape, it is sufficient that n1 <n3 <n2, n1 = n3 <n2, or n3 <n1 <n2. In this case, each microlens functions as a positive lens.
[0051]
  FIG. 3 shows another embodiment of the image display device as an explanatory diagram.
  As shown in FIG. 3A, in this embodiment, the microlenses of the first microlens array 1b provided in close contact with the spatial light modulation element 4b are concave, and the microlenses of the second microlens array 3b. The lens is convexIt is.The whole is integrated by appropriate means.
[0052]
  The microlens array in the first microlens array 1b overlaps the pixel array in the spatial light modulator 4b, but the microlens array pitch of the second microlens 3b is set to be the first microlens array 1b. In two directions (a horizontal direction in the figure and a direction perpendicular to the drawing) by a half pitch with respect to the arrangement pitch of the micro lenses inIt's off.
[0053]
As shown in FIG. 3B, the light 5b collected by the microlens L3b of the second microlens array is incident on the periphery of the first microlens array 1b and is applied to the pixel by the negative power of the microlens L1b. The light is efficiently collected.
[0054]
  Contrary to the example of FIG. 3, the microlenses of the first microlens array are convex and the microlenses of the second microlens array are concave.EvenIncident light can be efficiently collected toward the pixel.
[0055]
【Example】
  Below, an image display deviceThe example regarding is given.
  Example 1
  Pixel size: 14μm square
  Refractive index of resin filled in gaps between microlens arrays: 1.4
  First micro lens array
  Refractive index: 1.52 Micro lens (concave) radius of curvature: 25 μm
  Thickness of the first microlens array: 30 μm
  Second micro lens array
  Refractive index: 1.52 Micro lens (convex) radius of curvature: 25 μm
  Micro lens array spacing (from the center of the micro lens of the second micro lens array to the end of the micro lens of the first micro lens array): 3 μm
  Half width of profile: 6.2 μm
  Light utilization efficiency: 90%
  Also in the first embodiment, since the “half width of profile” is narrow and the light utilization efficiency is high, a high-definition and bright projection image can be realized.
[0056]
FIG. 4 is an explanatory view showing another embodiment of the image display apparatus.
[0057]
  In FIG. 4A, on the microlens formation surface of the first microlens array 1e provided in close contact with the spatial light modulation element 4e, a gap 10 is formed between the arranged microlenses 1e1.Yes,The gap 10 is a “flat surface”. When the pixel size (pixel pitch) in the spatial light modulator 4e is “d”, when the radius of curvature r of the microlens of the first microlens array 1e is smaller than the above d (in the case of a square pixel) For example, r <(d / 2)). The microlens 1e1 has a concave shape. The whole is integrated by appropriate means.
[0058]
  The arrangement pitch of the microlenses of the first microlens array 1e and the second microlens array 3e is shifted from each other by ½ pitch in the horizontal direction of the drawing and the direction orthogonal to the drawing. The microlens 3e1 formed on the microlens array 3e has a convex shape.
[0059]
  The square lattice shown in FIG. 4B shows the arrangement of the microlenses 3e1 when the second microlens array 3e is viewed from the optical axis direction. That is, each square in the lattice is a microlens 3e1. In other words, each microlens 3e1 has “square lens edges” when viewed from the optical axis direction, and is adjacent to each other at these edges. That is, in the second microlens array 3e, the arrangement of the microlenses 3e1 is “dense”.It is.
[0060]
In FIG. 4B, the microlens 1e1 of the first microlens array 1e is located at each lattice point of the lattice indicating the lens edge in the arrangement of the microlenses 3e1. The center of each microlens 3e1 corresponds to the center of each pixel in the spatial light modulation element 4e.
[0061]
Of the light 5 collected by the microlens 3e1 of the second microlens array, the light 5b that passes near the center of the microlens 3e1, that is, near the optical axis, is not significantly affected by the aberration of the microlens 3e1. It is not necessary to further collect the light 5b by the microlenses of the first microlens array, and only the light 5c that has passed through the periphery of each microlens 3e1 of the second microlens array is recessed in the first microlens array 1e. The light is condensed on the optical axis side of the micro lens 3e1 by the negative power of the micro lens 1e1.
[0062]
Examples relating to this embodiment will be described.
[0063]
  Example 2
  Pixel size: 14μm square
  Refractive index of resin filled in gaps between microlens arrays: 1.4
  First micro lens array
  Refractive index: 1.52 Micro lens (concave) radius of curvature: 25 μm
  Thickness of the first microlens array: 30 μm
  Second micro lens array
  Refractive index: 1.52 Micro lens (convex) radius of curvature: 25 μm
  Microlens array spacing (from the center of the microlens of the second microlens array to the flat part of the first microlens array): 2.4 μm
  The length of the flat portion between adjacent microlenses in the first microlens array (the distance between the edges of the microlenses 1e1 in the vertical and horizontal directions in FIG. 4B): 4 μm
  Half width of profile: 4.7 μm
  Light utilization efficiency: 97%
  The half width of the profile is very small, the light use efficiency is high, and a high-definition and bright projection image can be realized.
[0064]
  FIG. 5 shows the embodiment shown in FIG.Modified reference exampleIndicates.
  In this example, each microlens array 3e1 of the second microlens array has “square-shaped lens edges” when viewed from the optical axis direction, as in the example of FIG. ing. That is, in the second microlens array 3e, the arrangement of the microlenses 3e1 is “dense”.
[0065]
Further, on the first microlens array side, as in the example of FIG. 4, the concave microlens 1e1 is arranged at “each lattice point of the lattice indicating the lens edge in the arrangement of the microlenses 3e1”. However, in addition to this, convex-shaped microlenses 1e2 are arranged so as to be positioned at the respective central portions of the grating as viewed from the optical axis direction. That is, the array of microlenses 1e2 having positive power overlaps with the array of microlenses 3e1 and the array of pixels.
[0066]
The radius of curvature: r1 of the microlenses 1e1, 1e2 of the first microlens array is smaller than the pixel size: d (for example, r1 <(d / 2)), and the radius of curvature of the microlens 3e1 of the second microlens array: r2 is larger than the pixel size (for example, r2> d√ (2)) (in the case of a square pixel).
[0067]
Of the light collected by each microlens 3e1 of the second microlens array, the light passing through the lens periphery is condensed toward the pixel center by the negative power of the microlens 1e1. Further, the light passing through the center of the micro lens 3e1 is condensed toward the center of the pixel by the micro lens 1e2.
[0068]
That is, as compared with the case of FIG. 4, not only the light passing through the periphery of the microlens 3e1, but also the light passing through the center of the lens can be effectively collected toward the center of the pixel, so that the light can be efficiently collected on the pixel. it can.
[0069]
  That is, in FIG.Reference exampleThen, the first microlens array and the second microlens array are provided, and the arrangement of the microlenses 1e1 and 1e2 in the first microlens array and the arrangement of the microlenses 3e1 in the second microlens array correspond to the pixel arrangement. The arrangement of the microlenses 1e2 and 3e1 corresponds to overlap with the pixel arrangement, and the arrangement of the microlenses 1e1 corresponds to the pixel arrangement with a shift of ½ pitch in the vertical and horizontal directions.
[0070]
  FIG. 6 shows an image display device.FIG. 1 is an explanatory view showing an embodiment of the present invention.
  A first microlens array 1b 'is provided in close contact with the spatial light modulation element 4b, and a second microlens array 3b' is provided via a gap 2b ', and the whole is integrated. “Columnar” spacers 101 and 102 are formed outside the region of the microlens formation surface of the first microlens array 1b ′ and the second microlens array 3b ′.
[0071]
The spacers 101 and 102 are for maintaining the gap 2b ′ between the first and second microlens arrays. When the microlenses of the first and second microlens arrays 1b ′ and 3b ′ are produced by dry etching, the spacers 101 and 102 are provided. The spacers 101 and 102 are made to have the same interval, and are aligned after the production.
[0072]
In this way, not only can the gap between the first and second microlens arrays be made constant, but also the microlens arrays can be aligned within the plane of each other (by adjusting the pitch between each other, as shown in the figure). (1/2 pitch shift) is also facilitated. That is, when the pitch of the microlens array is shifted from each other as shown in the figure, the spacers 101 and 102 are prepared in advance at positions shifted by ½ pitch.
[0073]
A technique for producing a columnar spacer simultaneously with the microlens array is disclosed in Japanese Patent Laid-Open No. 2000-19307, and this method may be used.
[0074]
FIG. 7 illustrates one embodiment of the image projection apparatus in an explanatory manner.
Reference numeral 9 denotes a “light source”, reference numeral 10 denotes a “polarizing beam splitter”, reference numeral 11 denotes an “image display device”, reference numeral 12 denotes a “projection lens”, and reference numeral 13 denotes a “screen”.
[0075]
A light beam that is S-polarized light is incident on the polarization beam splitter 10 from the light source 9, reflected by the polarization beam splitter 10, and incident on the image display device 11. In the image display apparatus, as described with reference to FIGS. 1 to 6, the first and second microlens arrays are brought close to each other with a gap, and the spatial light modulation elements are arranged in close contact with the first microlens array. The spatial light modulator is a reflective liquid crystal light valve.
[0076]
When the liquid crystal light valve is driven by an image signal, the reflected light beam in the pixel corresponding to the image to be displayed is converted into a P-polarized state with respect to the polarization beam splitter. This light beam passes through the polarization beam splitter 10 and is formed and displayed as a projection image on the screen 13 by the projection lens 12.
[0077]
In the spatial light modulator, the pixel array 14 is a dense array as shown in FIG. 7B, but the incident light becomes a spot smaller than the pixel size on each pixel by the microlens array. The image projected by the projection lens 12 becomes an image 15 with a gap as shown in FIG. That is, the image 15 is a high definition image. The light source is mainly a white lamp such as a halogen lamp or an ultra-high pressure mercury lamp, but may be a laser or LED.
[0078]
In the pixel projection device of FIG. 7, when the image display device 11 is vibrated at high speed in a plane orthogonal to the optical axis of the projection lens 12 using a piezoelectric element or the like, a projected high-definition image 15 is obtained. Since the gap between the pixel images is finely displaced at high speed, a good high-definition image in which the gap is not conspicuous can be realized.
[0079]
【The invention's effect】
As described above, according to the present invention, a novel image display device and a novel image projection device using the image display device can be realized. As described above, the image display apparatus of the present invention condenses the incident light beam on each pixel of the spatial light modulator using the two microlens arrays, so that the power of the microlens of each microlens array can be set without difficulty. Thus, light can be efficiently collected on each pixel, and light utilization efficiency is high, so that a high-definition and bright projection image can be realized. Further, since the configuration of the image display device is simple, it can be easily and inexpensively manufactured.
[0080]
Therefore, an image projection apparatus using this image display apparatus can display a bright, high-definition and good image.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a reference example of an image display device.
FIG. 2 is a diagram for explaining an embodiment of an image display device.
FIG. 3 is a diagram for explaining an embodiment of an image display device.
FIG. 4 is a diagram for explaining an embodiment of an image display device.
FIG. 5 shows the embodiment of FIG.Reference example with changedIt is a figure for demonstrating.
FIG. 6 is a diagram for explaining an image display apparatus using a microlens array in which spacers are formed.
FIG. 7 is a diagram for explaining an embodiment of an image projection apparatus.
FIG. 8 is a diagram for explaining the light condensing property of a microlens.
[Explanation of symbols]
  1 First microlens array
  2 gap
  3 Second microlens array
  4 Spatial light modulator

Claims (8)

A spatial light modulation element that spatially modulates the intensity of transmitted light or reflected light; and first and second microlens arrays, wherein the pitch of the lens arrangement in the first and second microlens arrays is the same as that in the spatial light modulation element. Equal to the pitch of the pixel array,
The first and second microlens arrays are opposed to each other with a predetermined gap therebetween, and close to the first microlens array on the opposite side of the second microlens array via the first microlens array. Closely arrange the spatial light modulation element,
In the first microlens array and the second microlens array, one of the first microlens array and the second microlens array is shifted from the other by a half pitch in the microlens arrangement pitch in at least one direction . The lens arrangement of the microlens array is adjusted with respect to the spatial modulation element so as to overlap the pixel arrangement ,
Of the first microlens array and the second microlens array , any one microlens in one microlens array and half in at least one direction with respect to the one microlens in the other microlens array. An image display apparatus , wherein the light is condensed on each pixel of the spatial light modulator by at least two microlenses shifted in pitch . The image display device according to claim 1,
An image display device in which a resin is filled between the first and second microlens arrays. The image display device according to claim 1 or 2,
An image display device, wherein the microlenses of the first microlens array have a convex shape, and the microlenses of the second microlens array have a concave shape. The image display device according to claim 1 or 2,
An image display device, wherein the microlenses of the first microlens array have a concave shape, and the microlenses of the second microlens array have a convex shape. The image display device according to any one of claims 1 to 4,
An image display device having a gap between microlenses in at least one of the first and second microlens arrays. The image display apparatus according to any one of claims 1 to 5,
An image display device, wherein the arrangement of microlenses is dense in at least one of the first and second microlens arrays. The image display device according to any one of claims 1 to 6,
An image display device comprising a spacer for maintaining and / or adjusting a gap and / or position between first and second microlens arrays.   An image projection apparatus comprising: the image display apparatus according to claim 1; a light source; and a projection lens.

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