JPH09307697A - Microlens array, image sensor and optical image transmission element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the depth of field of a micro lens array by supporting fixedly a flat support member having holes at prescribed pitches to a support hole of the support member so as to provide a function of limiting or preventing mutual overlap of images by a plurality of identical micro lenses. SOLUTION: A luminous flux made incident from an upper part of each micro lens 1-1 of a micro lens array is refracted at a refraction plane of the incident side, collected once in each micro lens, part of the light is reflected in a light reflection film 1-3 of a support hole wall face, refracted at a lower refraction plane and outputted from each micro lens 1-1. In the micro lens array, a support member 1-2 is of light shut-off property and the size of support holes is selected depending on a pitch of the support hole arrangement so that the overlap of images by the micro lenses 1-1 is limited or prevented. Thus, the support member 1-2 limits or prevents overlapped images by the micro lenses 1-1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens, an image sensor and an optical image transmission device.

[0002]

2. Description of the Related Art In a conventionally known microlens array, images formed by individual microlenses overlap each other at their periphery to form a synthetic image, so that the synthetic aperture angle becomes large and the depth of field becomes shallow. There was a problem.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to realize a novel microlens array with an improved depth of field. Another object of the present invention is to realize a novel image sensor with less crosstalk. Another object of the present invention is to realize a novel optical image transmission device using the novel microlens array.

[0004]

The "microlens array" of the present invention has a holding member and a plurality of microlenses (claim 1).

The "holding member" has a flat plate shape, and has a plurality of holding holes having the same shape and independent from each other, which are formed at a predetermined pitch. That is, adjacent holding holes are not connected to each other. The plurality of “microlenses” are equivalent to each other and are fixedly held one by one in each holding hole of the holding member. The holding member has a function of limiting or preventing overlapping of images by the microlenses. in this way,
Since the holding member limits or prevents the images of the respective microlenses from overlapping with each other, the synthetic aperture angle is effectively reduced and the depth of field is improved.

The holding member may be "light-blocking" and the holding holes may be sized to a pitch of the holding holes array so as to limit or prevent mutual overlapping of images by the microlenses. It can be set accordingly (claim 2). To make the holding member light-shielding, the material itself of the holding member may be a light-shielding material such as metal, or a light-absorbing antireflection film is formed on the surface of a light-transmitting material such as glass or plastic. However, a light blocking property may be realized by this antireflection film. When the antireflection film is provided, the side of the antireflection film is the light incident side of the microlens (claim 3). Of course, the antireflection film may be formed on the incident side surface of the holding member made of a light shielding material. The light-absorptive antireflection film on the incident side of the microlens has the meaning of eliminating the effect of stray light on the image forming action of the individual microlenses.

In the microlens array according to claim 1, 2 or 3, "the wall surface of the holding hole in the holding member is made to be light-reflecting so that the light incident on each microlens is reflected". 4). As described above, the wall surface of the holding hole is made light-reflecting and the light incident on the microlens is reflected by the wall surface, whereby the transmission efficiency of the light transmitted by the microlens can be improved. In order to make the wall surface of the holding hole light-reflective, the material of the holding member may be metal or the like, and the reflectivity of the surface may be used, or a light-reflecting film may be formed on the wall surface.

As the material of the holding member, ceramics, silicon or the like can be used in addition to the above-mentioned metals, plastics and glass. A holding member made of metal, glass, ceramics, or silicon has excellent resistance to environmental changes such as temperature and humidity.

The microlens fixedly held by the holding member is formed by using "photocurable resin" as a material,
It can be fixed to the holding member by light irradiation (Claim 6), or can be configured as a "ball lens made of optical glass" (Claim 7). When using a ball lens, two or more ball lenses may be held in one holding hole of the holding member, and one microlens may be configured by a plurality of ball lenses. Further, when curing the photocurable resin, in addition to light irradiation,
Heating (post cure) can be performed.

Planar shapes of individual microlenses in these microlens arrays (shapes viewed from the optical axis direction)
Can be a circle, an ellipse, a polygon such as a quadrangle, etc., and the shape of the lens surface can be a spherical surface, a cylinder surface, a toroidal surface, a spherical surface, etc., and the lens function can be anamorphic. It is possible.

In the microlens array according to any one of claims 1 to 7, the array of microlenses is one-row linear or two-row staggered, or two-dimensional matrix or two-dimensional staggered. be able to. The two-dimensional matrix shape means that the microlenses are arranged in a predetermined pitch in both the vertical and horizontal directions (the vertical pitch and the horizontal pitch may be the same or different), and the two-dimensional staggered pattern is formed. The shape means that the array of microlenses has three or more rows in both the vertical and horizontal directions.
This means that the arrangement of microlenses in two adjacent rows is staggered.

By combining the microlens array as described in any one of claims 1 to 7 with these and a photoelectric conversion element array, a one-dimensional or two-dimensional image sensor can be constructed and combined with a light emitting element array. The optical image transmission device can also be configured by the above.

That is, the "image sensor" of the present invention is
A photoelectric conversion element array in which a plurality of minute photoelectric conversion elements are one-dimensionally or two-dimensionally arranged in a predetermined pattern, and a plurality of microlenses arranged in the same pattern as the arrangement of photoelectric conversion elements in this photoelectric conversion element array are provided. The above-mentioned microlens array having the photoelectric conversion elements and the microlenses correspond to each other at a ratio of 1: 1 and the image light flux incident on each microlens is condensed on the corresponding photoelectric conversion elements. It is configured to be integrated with.

The "optical image transmission device" of the present invention is
The above micro having a light emitting element array in which a plurality of minute light emitting elements are arranged in a predetermined pattern one-dimensionally or two-dimensionally, and a plurality of microlenses arranged in the same pattern as the arrangement of the light emitting elements in the light emitting element array. The lens array is such that each light emitting element and each microlens are 1: 1.
And the light fluxes emitted from the individual light emitting elements are integrally formed so as to enter the corresponding microlenses.

Further, the above-mentioned microlens array in which the microlens arrays are arranged in a two-dimensional matrix or a two-dimensional staggered pattern can give directivity to the light from the light source array, for example, for liquid crystal display. Can be effectively used as an optical element of a backlight panel.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows one embodiment of a microlens array according to claims 1, 2, 3, and 4. Reference numeral 1-2 indicates a holding member. Holding member 1
Reference numeral 2 is a flat plate, and a plurality of independent holding holes are formed at a predetermined pitch. Each holding hole has the same shape,
A light-reflecting film 1-3 is formed in the interior thereof so that the wall surface is light-reflecting (claim 4), and each of the holding holes has a microlens 1 for forming an erecting equal-magnification image. 1 is fixedly held.

In FIG. 1, the upper surface is the light incident side to the microlens 1-1, and the light absorbing antireflection film 1-4 is formed on the surface of the holding member 1-2 at this light incident side. (Claim 3).

A light beam incident on each microlens 1-1 of the microlens array of FIG. 1 from the upper side of the drawing is refracted by a refracting surface on the incident side, and is once condensed within the microlens, for example, and then a part thereof is collected. The light is reflected by the light reflection film 1-3 on the wall surface of the holding hole, refracted by the lower refraction surface, and emitted from each microlens 1-1. Contrary to the above, while the light flux incident from the refracting surface on the incident side is refracted, a part of the light flux is reflected by the light reflecting film 1-3 to be condensed and then emitted while being refracted on the refracting surface on the exit side. You can also choose to do so.

In this embodiment, the holding member is light-blocking and holds the size of the holding holes formed so as to limit or prevent mutual overlapping of images by the microlenses 1-1. The holding member 1-2 is set according to the pitch of the hole arrangement (claim 2).
Has a function of limiting or preventing mutual overlapping of images by the microlenses.

FIG. 2 is an explanatory view showing one embodiment of the microlens array according to claims 1, 2, 3, 4, and 6. Reference numeral 2-2 indicates a holding member. Holding member 2-2
Has a flat plate shape and has a plurality of independent holding holes formed at a predetermined pitch. The inside of each holding hole is a light reflecting film 2-3.
And the wall surface is light-reflecting (claim 4), and one microlens 2-1 is provided in each holding hole.
Is fixedly held. In this embodiment, each microlens 2-1 is a "ball lens made of optical glass" (claim 6).

In FIG. 2, the upper surface is the light incident side to the microlens 2-1, and on this light incident side, a light absorbing antireflection film 2-4 is formed on the surface of the holding member 2-2. (Claim 3).

A light beam incident on each microlens 2-1 of the microlens array of FIG. 2 from the upper side of the drawing is refracted by the refracting surface on the incident side, and a part of the light reflecting film 2-3 on the wall surface of the holding hole.
And is refracted by the lower refracting surface and emitted from each microlens 2-1.

Also in the embodiment shown in FIG. 2, the holding member 2-2 is light-shielding, and the size of the holding holes formed limits or prevents mutual overlapping of images by the microlenses. Thus, the holding holes are set according to the pitch of the holding hole arrangement (claim 2), and thus the holding member 2-2 has a function of limiting or preventing mutual overlapping of images by the microlenses.

FIG. 3 is an explanatory view showing one embodiment of the image sensor of the present invention constructed by using the microlens array of the type shown in FIG. In the photoelectric conversion element array 41, a plurality of minute photoelectric conversion elements 40
Are arranged in a row at a predetermined pitch in a direction orthogonal to the drawing. The microlens array 10 has a plurality of microarrays arranged in one row in the direction orthogonal to the drawing in the same pattern as the arrangement of the photoelectric conversion elements 40 in the photoelectric conversion element array 41 (the same pitch as the arrangement pitch of the photoelectric conversion elements 40). It has a lens 11.

The microlens array 10 and the photoelectric conversion element array 41 correspond to each photoelectric conversion element 40 and each microlens 11 at a ratio of 1: 1, and the image light flux incident on each microlens corresponds thereto. It is integrated by an appropriate integration means 42 such as a casing so as to collect light on the photoelectric conversion element. Individual microlens 1
The optical axis of 1 passes through the central portion of the corresponding photoelectric conversion element 40.

As shown in FIG. 3, contact glass 30
If the original surface is placed on the original surface and the original 0 is moved in the direction of arrow A while the original surface portion on the microlens array 10 is illuminated by an illumination means (not shown), the original is pixelated by the individual microlenses 11. Then, an image is formed on the corresponding photoelectric conversion element 40, photoelectrically converted by the photoelectric conversion element 40, and read.

FIG. 4 shows the optical image transmission device of the present invention.
1 is an explanatory view showing an embodiment of the present invention configured by using a microlens array of the type shown in FIG. 1 (in order to avoid complication, the same reference numerals are used as in FIG. 3).

In the light emitting element array 50, a plurality of minute light emitting elements 51 are one-dimensionally arranged in one row at a predetermined pitch, and in the microlens array 10, the light emitting elements 51 in the light emitting element array 50 are arranged. And a plurality of microlenses 11 arranged in the same pattern (the same pitch as the arrangement pitch of the light emitting elements 51).

The light emitting element array 50 and the microlens array 10 are arranged such that the light emitting elements 51 and the respective microlenses 11 correspond to each other in a ratio of 1: 1 and the luminous flux emitted from each light emitting element corresponds to the corresponding microlens. It is integrated by an appropriate unifying means (casing or the like) not shown so as to enter the lens and form an image of the light emitting element corresponding to the image forming surface 60 (generally the surface of the photoconductor). The optical axis of each microlens 11 passes through the center of the corresponding light emitting element.

The "one-dimensional image" represented by the combination of the light-emitting elements 51 that are turned on is transmitted by the microlens array 10 and imaged on the image plane 60. By repeating such optical image transmission while moving the image plane 60 in the direction orthogonal to the drawing, a two-dimensional optical image can be transmitted (exposed) to the image plane 60.

In the embodiment shown in FIG. 1, the "shape seen from the optical axis direction" of the microlens 1-1 is shown in FIG.
Although the shape is circular as shown in FIG.
A polygon (such as a hexagon in the figure) like the microlens 1-11 shown in FIG. 5 or a microlens 1-12 shown in FIG.
It may be oval like.

The array pattern of the microlenses in the microlens array is not limited to the one-dimensional linear array described above, and the microlenses 6-1 shown in FIG.
It may be a two-row zigzag array as shown in FIG.
It may be a three-dimensional matrix or a two-dimensional staggered pattern.

[0033]

EXAMPLES Specific examples will be described below. Among Examples 1 to 5 described below, Examples 1 to 4 relate to the embodiment described with reference to FIG. 1, and Example 5 relates to the embodiment described with reference to FIG. is connected with.

Example 1 The microlens array of Example 1 is for an image sensor (claim 8), and the photoelectric conversion element array to be integrated with the microlens array is:
Photoelectric conversion element with light receiving part diameter: 70 μm pitch: 125 μ
m are arranged in a straight line in one column.

The microlens array was manufactured by the following procedure. Width: 12 mm, length: 300 mm, thickness: 500 μm Aluminum substrate (previously formed with a plurality of positioning holes) A computer-controlled press machine that inputs the desired numerical values,
Diameter: 100 μm “Circular holes”, pitch for holding holes:
125μm 1700 pieces per line (length: 21.25m
m) Drilled.

Next, aluminum was vacuum-deposited on this plate. At this time, if necessary, a "plasma treatment" can be performed as a pretreatment for vacuum vapor deposition. The vapor-deposited aluminum film imparts light reflectivity as a light reflection film to the wall surface of the hole formed in the aluminum substrate. In this embodiment, the "holding hole hole" is mechanically drilled, so the wall surface of the hole is not a mirror surface. Therefore, aluminum was vapor-deposited to make this portion a mirror surface. In this way, a series of "holding holes" having a light-reflecting wall surface was obtained.

Next, an ultraviolet light curable resin having a viscosity of 2000 cps (manufactured by Kyoritsu Chemical Industry Co., Ltd., which is commercially available as a high refractive index adhesive) is uniformly applied onto the aluminum substrate to form a hard urethane. It was pushed into the holding hole with a squeegee (made of fluororesin). The pushed resin was extruded from the respective holding holes of the substrate to the surface on the opposite side, and bulged in a convex shape from the respective holding hole portions.

At this time, the amount of resin protruding from the back surface of the substrate differs depending on the hole diameter for holding the substrate, the extrusion pressure, the hardness of squeegee, the amount of deflection of the substrate, the surface tension of the resin, and the thixotropy of the resin. The "bulge convex shape" on the back side differs depending on the balance between the amount of protrusion and gravity. Therefore, by controlling the above-mentioned various amounts, it becomes possible to make the shape of the convex surface raised on the back surface of the substrate a "desired spherical shape".

When the convex shape of the resin raised from each holding hole became a desired spherical shape, the resin was cured by irradiating it with ultraviolet light, and heating was performed as a post-baking for complete curing. The surface on the side where the squeegee is pressed is
It became a flat surface with the same height as the substrate surface.

The optical component thus obtained is shown in FIG.
Is indicated by reference numeral 1a. Reference numeral 1-2a is an aluminum substrate,
Reference numeral 1-3a indicates a vapor deposited film of aluminum. Code 1-
Reference numeral 1a represents a cured ultraviolet light curable resin.

A photoresist is applied to the upper surface of the optical component 1a in FIG. 7, and the photoresist is left only on the convex portion of the resin 1-1a by a photolithography method, and a chromium multilayer film is formed on the entire surface from above. Then, the resist was removed by the lift-off method, and the chromium multilayer film remaining on the portion other than the convex surface of the resin was used as the light absorbing antireflection film 1-4.

In the same manner as above, an optical component shown by reference numeral 1b in FIG. 7 was produced. Reference numeral 1-2b indicates an aluminum substrate, and reference numeral 1-3b indicates an aluminum vapor deposition film.
Reference numeral 1-1b indicates a cured ultraviolet light curable resin.

These two optical components 1a and 1b are aligned with each other by utilizing the previously formed alignment holes, and they are joined using the same resin as described above. A microlens array was obtained. In this microlens array, the aluminum substrate 1-2a,
1-2b constitutes a holding member (reference numeral 1-2 in FIG. 1), and the resins 1-1a and 1-1b integrally form individual microlenses (reference numeral 1-1 in FIG. 1). 1-3a, 1
-3b forms a light reflecting film (reference numeral 1-3 in FIG. 1) that imparts light reflectivity to the wall surface of the holding hole of the holding member.

The microlens array thus manufactured and the photoelectric conversion element array (contact type sensor) are aligned with each other, and each microlens and each light receiving portion are assembled and integrated so as to have a 1: 1 correspondence. .

The image sensor thus manufactured was able to obtain sufficient performance as a "low density image sensor" of 200 dpi. 125 micro lenses
Since the microlenses are arranged at a pitch of μm and the diameter of the microlenses (holding hole diameter) is 100 μm, the distance between adjacent microlenses is 12.5 μm due to the holding member. Since this is substantially prevented, the depth of field is large. Therefore, the accuracy of adjusting the distance between the microlens array and the document surface is greatly eased. Further, the action of the antireflection film has no influence of stray light, and the light reflection film improves the light transmission efficiency of the light flux for reading.

It should be noted that components may be formed using a substrate having a size larger than that of the above substrate, and then cut into the above size.

By the same manufacturing method as described in the first embodiment, similar microlenses are arranged in a zigzag in two rows as shown in FIG. 6 and combined with a photoelectric conversion element array having a similar arrangement structure. , 400 dpi, it was possible to obtain sufficient performance as a medium density sensor.

Example 2 The microlens array of Example 2 is for an image sensor (claim 8), and the photoelectric conversion element array to be integrated with the microlens array is:
Photoelectric conversion element with light receiving part diameter: 35 μm pitch: 62.5
It is arranged in a straight line in one column with a size of μm.

The microlens array was manufactured in the same manner as in Example 1. That is, width: 12 mm, length: 30
0mm, thickness: 500μm a plurality of positioning holes in the aluminum plate in advance, based on these holes, the press program controlled by the computer entered the desired numerical value, the diameter of 57.7μm Circular holes,
After the photoelectric conversion elements of the photoelectric conversion element array were arranged at the same pitch: 62.5 μm, 3400 pieces (length: 21.25 mm) for holding holes were linearly arranged in one row, and after plasma treatment, aluminum was formed. It was vacuum deposited.

Viscosity as material for microlens: 120
UV-curable resin of 0 cps (Kyoritsu Chemical Industry Co., Ltd.)
Manufactured and sold as a high-refractive-index adhesive) in the same manner as in Example 1 below, to obtain an optical component as indicated by reference numeral 1a in FIG. 7
An optical component as indicated by reference numeral 1b was obtained. The two optical components produced as described above were aligned using the previously formed alignment holes, and were joined using the same resin as described above. Thus, a microlens array of the type shown in FIG. 1 was obtained.

This is aligned with the above-mentioned photoelectric conversion element array (contact type sensor) in which the photoelectric conversion elements having a light receiving portion diameter of 35 μm are linearly arranged in one row with a pitch of 62.5 μm, and each microlens The photoelectric conversion elements were assembled and integrated so that the light-receiving parts had a 1: 1 correspondence. The image sensor manufactured in Example 2 was able to obtain sufficient performance as a "medium density image sensor" of 400 dpi.

It is also possible to use a substrate having a size larger than that described above, and finally cut and align it to the size described above.

Example 3 The microlens array of Example 3 is for an optical image transmission device (claim 9) and is of the type shown in FIG. The light emitting element array combined with the microlens array is a 600 dpi LED array. The microlens array is of the type shown in FIG. 1 as described above,
Each microlens forms an inverted equal-magnification image of the LED.

The microlens array was manufactured by the following procedure. As shown in FIG. 8, a positive photoresist 81 is coated on a SUS substrate 80 having a thickness of 2 mm,
By a conventional method of photolithography, the photoresist 81 was left only in the pattern for alignment with the target microlens portion, and the other portions were removed.

That is, as shown in FIG. 8A, a mask 82 (having a circular pattern 82a with a diameter of 38.0 μm and a pitch of 42. UV light U.V. The substrate was exposed by V, developed and rinsed, and the pattern of the photoresist 81 following the pattern of the mask 82 was left on the substrate 80 (FIG. 8B).

Next, the substrate 80 was immersed in an electrolytic nickel plating bath for high speed plating (FIG. 8 (c)). After that, the resist was removed (FIG. 8D), and the plating plate 90 formed by nickel plating was peeled from the SUS substrate 80.

As shown in FIG. 8E, holes 91 are opened in the plating plate 90 according to the arrangement of the microlenses, and these holes serve as holding holes. That is, the plating plate 90 serves as a holding member. Since the plating plate 90 is made by plating, the surface thereof is "mirror-like", and the wall surface of the holding hole 91 is light reflective.

The holding hole 91 has a slightly smaller hole diameter in the growth direction of the plating (upward direction in FIG. 8 (e)), and the wall surface is slightly tapered. The thickness of the plating plate 90 is 25 μm.

Next, a positive photoresist is applied to the molybdenum plate, and the density is gradually increased from the center toward the periphery, so that a circular density distribution for a microlens (diameter: 3) is obtained.
Array of microlenses (pitch: 42.
A photoresist is exposed using a "density distribution type photolithographic mask" having a linear pattern of 0 μm), and developed and rinsed to create a concave mold shape corresponding to the convex lens surface shape of the target microlens. did.

The molybdenum plate having this photoresist was etched by a dry etching apparatus in which a fluorine-based gas was introduced, and the surface shape of the photoresist was transferred to the molybdenum plate. The molybdenum plate having the concave mold shape corresponding to the convex lens surface shape of the target microlens in this manner becomes the first mold.

A second manufacturing method similar to that of the first mold is used.
The mold was made of a molybdenum plate. In the concentration distribution type photolithographic mask used for manufacturing this second mold, the circular concentration distribution has a diameter of 41.5 μm and a pitch of 4
2.0 μm. The surfaces of the first and second molds were treated with fluorine plasma to improve the mold release performance as the mold.

Thus, the first and second molds have a pitch of 4
2.0 μm is the same, but the diameter of the concave shape for each microlens surface is different. This is because the wall surface of the holding hole in the plating plate 90 made of nickel used as the holding member has a slight taper.

As shown in FIG. 9 (a), a plating plate 90 made of nickel is fixed on a first mold 93 made of molybdenum, and an ultraviolet light curing resin 10 manufactured by Kyoritsu Chemical Industry Co., Ltd. is used.
0 (high-refractive-index adhesive, viscosity: 1000 cps) was uniformly applied on the plated plate 90, and was pushed into the holding hole by a squeegee of hard urethane. The resin 100 having a relatively high viscosity was extruded from the holding hole to fill the concave shape of the first mold 93.
In this state, the resin 100 was cured by irradiation with ultraviolet rays.
At this time, heating was performed as a post-baking in order to completely cure. The surface on the side where the squeegee is pressed is the plated plate 9
It became a flat surface with the same height as the 0 surface. In this way,
A first refracting surface was obtained.

Then, using a second mold, a second refraction surface was obtained with the above resin of high refractive index adhesive. That is, the resin is applied on the second mold and irradiated with ultraviolet light to cure the resin,
After forming the refracting surface of No. 1, the above resin is applied to the surface of the plating plate 93 opposite to the side on which the first refracting surface is formed, and the resin is heated in alignment with the second mold. The resin having the second refraction surface formed by the second mold was adhered and fixed to the plating plate 93.

The lens surface portion on the second refraction surface side is covered with a photoresist by a photolithography method, and then a chromium multilayer film is formed as a light absorbing antireflection film 101, and the photoresist is removed by a lift-off method. It was removed (FIG. 9 (b)). In this way, a microlens array of the type shown in FIG. 1 was obtained.

This microlens array was aligned with the LED array which is a light emitting element array, and each microlens and each light emitting portion were assembled and integrated so as to have a 1: 1 correspondence. The LED array is formed by arranging light emitting portions having a diameter of 20 μm in a straight line with a pitch of 42.0 μm.

The optical image transmission device thus obtained is composed of 6
It was possible to obtain sufficient performance as a high-density writing optical system of 00 dpi.

In the same manner as in Example 3, the lenses having the above pitch are arranged in a zigzag pattern in two rows, and combined with an LED array having a similar arrangement structure to obtain 1200d.
Sufficient performance could be obtained as a high density writing optical system for pi.

Example 4 The microlens array of Example 4 is also for an optical image transmission device (claim 9) and is of the type shown in FIG. The light emitting element array combined with the microlens array is a 600 dpi LED array. As described above, the microlens array is of the type shown in FIG. 1, and each microlens forms an inverted equal-magnification image of the LED.

The microlens array was manufactured by the following procedure. The same holding member as in Example 3 is used in Example 3
A plated plate having a thickness of 25 μm was produced by the same method as described above.

Each mold for the first refracting surface and the second refracting surface was manufactured using a molybdenum plate. The method of making the mold is the same as in Example 3, except that FIG.
As shown in (a), a gate part 97 for resin flow was separately manufactured in the second mold 95 to connect the individual microlens surface shapes a.

The gate portion may be provided outside the effective diameter of the lens, or may be provided so as to directly connect the individual lenses as in the example of FIG. Further, even without providing a gate portion, a mold surface portion 96 having a lens surface shape aperture larger than a required microlens effective diameter is manufactured like a mold 95 ′ shown in FIG. 10B. The resin may flow in the adjacent mold surface portions. That is, in the die surface portion of the die, the microlens effective diameter portion may have a desired curvature. The surface portions of the first and second molds were subjected to “surface treatment” with a fluorine compound of triazine in order to enhance releasability.

The two molds produced as described above are
Align the holes using the pre-made alignment holes, sandwich the nickel plating plate between these molds, and use the resin of the high-refractive-index adhesive to form the microlenses by a normal molding process. Molded.

A light absorbing antireflection film was formed as a chromium multilayer film on the first refracting surface side in the same manner as in Example 3 to obtain a microlens array of the same type as shown in FIG. .

This microlens array is aligned with the LED array, and each microlens and each light emitting portion have a 1: 1 ratio.
Assembled and integrated so as to be compatible. The LED array is formed by arranging light emitting portions having a diameter of 20 μm in a straight line with a pitch of 42.0 μm. This optical image transmission device has 6
It was possible to obtain sufficient performance as a "high-density writing optical system" of 00 dpi.

In addition, by arranging microlenses having the same pitch in a zigzag pattern in two rows and combining with an LED array having a similar arrangement structure, a high density of 1200 dpi is obtained by the same method as that of the fourth embodiment. It was possible to obtain sufficient performance as a writing optical system.

When the lens surface of the microlens is molded by using a mold as in the third and fourth embodiments, the shape of the microlens surface can be a cylinder surface or an anamorphic surface.
A spherical surface and the like can be easily formed.

Example 5 The microlens array of Example 5 is for an optical image transmission device and is of the type shown in FIG.

A microlens array was manufactured as follows. First, the holding member was formed by the following method.

As shown in FIG. 11A, thickness: 100
Positive photoresist 71 on μm silicon substrate 70
And a light-shielding portion 85a according to the arrangement pattern of the holding holes.
UV light U.S.P. is transmitted through a mask 85 having a diameter of 120 μm and a pitch of 127 μm. Exposure was performed by irradiating V, followed by development and rinsing (FIG. 11 (b)).

Next, the substrate 70 was immersed in a wet etching solution for silicon to perform wet etching (FIG. 11C), and then the photoresist 71 was removed.
The cross-sectional shape of the holding hole formed by wet etching in the silicon substrate 70 is as shown in FIG.
The hole diameter decreased in the direction of etching, and the shape was slightly tapered (the figure is exaggerated).

Then, aluminum is vacuum-deposited on the substrate 70 to make the wall surface of the holding hole light-reflective, and then a ball lens having a diameter of 120 μm made of optical glass is fixed to each holding hole to cure the ultraviolet light. It was fixed using an adhesive. An antireflection film made of a chromium multilayer film was formed on the surface to be the light incident side in the same manner as in Examples 1 to 4.

In this way, a microlens array of the type shown in FIG. 2 was obtained. In this microlens array, each microlens has a function of emitting an incident light beam without forming an image inside and forming an image.

The microlens array thus obtained is used as an LED array (diameter: 20) which is a light emitting element array.
The light emitting parts of μm were aligned in a straight line with a pitch of 127 μm), and each microlens and each light emitting part were assembled so as to have a 1: 1 correspondence and integrated.

The optical image transmission device manufactured in Example 5 has 2
It was possible to obtain sufficient performance as a "low-density writing optical system" of 00 dpi. In addition, a microlens having the same pitch is formed by the same method as that of the fifth embodiment.
By arranging them in a staggered array and combining them with an LED array having a similar arrangement structure, sufficient performance as a "medium density writing optical system" of 400 dpi could be obtained.

[0086]

As described above, according to the present invention, a novel microlens array, image sensor and optical image transmission device can be provided. In the microlens array of the present invention, since the holding member that holds the microlenses has a function of limiting or preventing mutual overlapping of images by the adjacent microlenses, the synthetic aperture angle is effectively reduced and the depth of field is reduced. Effectively deepen.

The microlens array according to claim 3 is
Since the light-absorbing antireflection film is formed on the surface of the holding member on the light incident side, it is possible to eliminate the influence of stray light on the imaging action of the microlens array.
In the microlens array according to the fourth aspect, since the wall surface of the holding hole for holding the microlens in the holding member is light reflective, the light transmission efficiency of the microlens array is good and the light utilization efficiency is high.

The image sensor of the present invention uses the above-mentioned microlens array and the photoelectric conversion element and the microlens array correspond to each other in a ratio of 1: 1, so that so-called crosstalk can be effectively prevented and good image reading can be performed.

The optical image transmission device of the present invention uses the above microlens array, and the light emitting device and the microlenses correspond to each other in a ratio of 1: 1, so that crosstalk between images transmitted by each microlens is prevented, which is preferable. Optical image transmission can be performed.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of a microlens array of the present invention.

FIG. 2 is a diagram for explaining another embodiment of the microlens array of the present invention.

FIG. 3 is a diagram for explaining one embodiment of the image sensor of the present invention.

FIG. 4 is a diagram for explaining one embodiment of the optical image transmission device of the present invention.

FIG. 5 is a diagram showing three examples of lens configurations of a microlens held by a holding member as seen from the optical axis direction.

FIG. 6 is a diagram showing a two-row zigzag arrangement, which is an example of an arrangement of microlens arrays.

FIG. 7 is a drawing for explaining the manufacture of the microlens array in Example 1.

FIG. 8 is a drawing for explaining the manufacture of the holding member in the third embodiment.

FIG. 9 is a diagram illustrating an example of a method of holding a microlens on a holding member according to a third embodiment.

FIG. 10 is a diagram for explaining two molds for lens surfaces of microlenses related to Example 4;

FIG. 11 is a drawing for explaining the production of the holding member related to Example 5;

[Explanation of symbols]

 1-1 Microlens 1-2 Holding member 1-3 Light reflection film 4-4 Antireflection film

Claims (9)

[Claims] 1. A flat plate-shaped holding member having a plurality of holding holes of the same shape and independent from each other, and a plurality of holding members that are fixedly held in the holding holes of the holding member and are equivalent to each other. The microlens array according to claim 1, wherein the holding member has a function of limiting or preventing overlapping of images by the microlenses. 2. The microlens array according to claim 1, wherein the holding member is light-blocking so that the size of the holding holes formed can limit or prevent mutual overlapping of images by the microlenses. , A microlens array characterized by being set according to the pitch of the holding hole array. 3. The microlens array according to claim 1 or 2, wherein a light-absorptive antireflection film is formed on the light-incident side of the holding member. 4. The microlens array according to claim 1, 2 or 3, wherein the wall surface of the holding hole in the holding member is light-reflecting and reflects the light incident on each microlens. . 5. The microlens array according to claim 1, 2 or 3 or 4, wherein each microlens is formed of a photocurable resin and is fixed to a holding member by light irradiation. Micro lens array. 6. The microlens array according to claim 1, 2 or 3 or 4, wherein each microlens is a ball lens made of optical glass. 7. The microlens array according to claim 1, 2 or 3 or 4 or 5 or 6, wherein the array of microlenses is one-row linear or two-row staggered, or two-dimensional matrix or two-dimensional staggered. A microlens array characterized by having a shape. 8. A photoelectric conversion element array in which a plurality of minute photoelectric conversion elements are arranged one-dimensionally or two-dimensionally in a predetermined pattern, and arranged in the same pattern as the arrangement of photoelectric conversion elements in this photoelectric conversion element array. And a microlens array having a plurality of microlenses, such that each photoelectric conversion element and each microlens have a 1: 1 correspondence, and the image light flux incident on each microlens corresponds to the corresponding photoelectric conversion element. The microlens array is integrated so as to collect light on the upper surface, and the microlens array according to any one of claims 1 to 7.
An image sensor, which is the microlens array described in 1. 9. A light emitting element array in which a plurality of minute light emitting elements are arranged one-dimensionally or two-dimensionally in a predetermined pattern, and a plurality of micros arranged in the same pattern as the arrangement of the light emitting elements in the light emitting element array. A microlens array having a lens is integrated so that each light emitting element and each microlens have a 1: 1 correspondence, and the luminous flux emitted from each light emitting element is incident on the corresponding microlens. And the microlens array is any one of claims 1 to 7.
An optical image transmission device, which is the microlens array described in 1.