JPH07248404A - Resin lens array and its production - Google Patents

Abstract

PURPOSE:To make it possible to produce a lens array with an inexpensive apparatus for production and material without requiring a high-temp. process and costly molds by extruding a resin into the through-holes of a holed plate and molding and solidifying lenses, thereby forming this lens array. CONSTITUTION:The unexposed photosetting resin 2 is first applied at a uniform thickness on one surface of a transparent plane substrate 1. The holed plate 4 arranged with plural pieces of the through-holes 41 having, for example, a cylindrical shape in parallel in the parts to be formed with the lenses consisting of a light shieldable material is prepd. The photosetting resin layer 2 is brought into tight contact with the holed plate 4 side. Next, the spacing between the transparent plane substrate l and the holed plate 4 is adjusted by a fine adjusting device 5 while the positional relation between both is maintained in parallel. More specifically, the spacing is gradually narrowed and the photosetting resin 2 is extruded into the through-holes 41 of the holed plate 4 and is built up to a spherical surface shape, by which lens parts 31 are molded. The spacing between both is fixed at the point of the time when the resin attains the desired lens shape. The photosetting resin 2 is cured from the transparent plane substrate 1 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens for efficiently condensing light on a photodetector composed of a plurality of elements such as a solid-state image pickup element, and an equal magnification combination of an image reading sensor such as a facsimile and an image scanner. Image lens,
And a resin lens array used as an imaging lens of an optical printer such as an LED printer.

[0002]

2. Description of the Related Art For example, in a lens array 3 as disclosed in FIG. 24 (FIG. 8) of Japanese Patent Laid-Open No. 55-90923, a female mold having a shape intended for glass or resin is used. The lens array sheet 30 is formed by injection molding or heating and softening, and then the lens array sheet 30 is attached to a separately prepared diaphragm 44.

Further, as shown in FIG. 21 (FIG. 9) of the above publication, the lens array 3 is simultaneously inserted from both sides by sandwiching the diaphragm 44.
There is disclosed a method of integrally molding the. Furthermore, after the lens molding process, a method of applying a light-shielding film to a target portion by printing, vapor deposition, sputtering, or the like has been performed for some time.

Further, ions having different refractive indexes are selectively distributed in the glass substrate by an ion diffusion method or the like, and the refractive index distribution due to the concentration difference is used to obtain a lens action in the form of a planar substrate lens array ( For example, JP-A-57-53702
No.) has been put to practical use.

[0005]

A lens array using glass as a lens medium is excellent in weather resistance, coefficient of thermal expansion, hygroscopicity, etc., and has high optical performance and good stability. As a manufacturing method thereof, in the molding method, a glass material is heated and molded at a high temperature, and therefore an extremely expensive molding die is required. Further, it is not a low-cost manufacturing method because it requires a slow cooling time after heating. Further, in order to change the lens diameter and the focal length, it is necessary to change the molding die.

Further, although the glass ion-exchange method does not require an expensive mold, it requires a large-scale high-temperature ion-exchange tank and a long ion-exchange time, which limits cost reduction. There is. From the above points, it is difficult to provide a low-cost lens array when the lens medium is glass.

On the other hand, when a resin is used as the material, a low cost lens array can be provided because of the low temperature process.
In the invention of the embodiment disclosed in FIG. 24 of 5-90923 (see FIG. 8), the lens array sheet 30 and the diaphragm 44 for blocking unnecessary light are separately manufactured, and the lens is aligned by performing precise alignment later. Array 3 was being assembled. The inside of the through hole 42 of the diaphragm 44 is filled with resin.

A long or large area lens array has a sheet-like shape, and a resin material having poor moisture resistance absorbs water and expands and contracts unevenly in the lens array plane,
Warping, twisting, and bending are likely to occur, and the change in the lens array size with time becomes extremely large. Therefore, it is extremely difficult to make the center of the diaphragm and the optical axis of each lens coincide with each other.

Particularly, in the case of a lens array that requires at least two lenses to obtain an erecting equal-magnification image, the two lens arrays and the plate with holes are separately manufactured and assembled with high precision and aligned optical axes. As a result, a great deal of cost is required for assembly. The embodiment disclosed in FIG. 21 of JP-A-55-90923 (see FIG. 9) is characterized in that the axes of the two lens groups can be easily aligned by adjusting the positions of the molding dies 8 on both sides. However, an expensive molding die or an apparatus such as injection molding is required, and since a cylindrical shape having a through hole corresponding to the drawn portion is injected into the resin, additional cost is required, and cost reduction is required. Not suitable.

On the other hand, in the resin gradient index lens array using the principle of polymerization of polymer resin, the light shielding film 32 forming the diaphragm as shown in FIG. 10 also serves as a mask for selectively preventing polymerization. It is possible to solve the above drawbacks and to form the gradient index lenses 33 on both surfaces (two lenses in two groups), but it is theoretically difficult to realize because it is necessary to form a cylinder 45 as a diaphragm in the medium. .

Further, in Japanese Patent Laid-Open No. 2-196201, a photosensitive resin 2 is sandwiched between a lens molding die 8 and a lens molding substrate 1, and the resin is cured by an ultraviolet ray source 6 to form the molding die as described above. A method for manufacturing a microlens array, which is characterized by peeling from a substrate, is disclosed. In this method, an expensive mold is required, and it is necessary to assemble the plate with a hole having a light-shielding function and the optical axis thereof in a separate step. (See Figure 11)

The present invention solves the above-mentioned problems,
An object is to provide an inexpensive resin lens array.

[0013]

In order to solve the above-mentioned problems, the present invention uses a resin material used in a low temperature process, extrudes the resin into the through holes of a perforated plate to mold and solidify the lens, and a lens array. A sheet is formed, and a resin lens array in which the lens array sheet and the plate with holes are adhered and fixed is manufactured.

[0014]

The resin layer for adhering the transparent flat substrate and the plate with holes is extruded into the openings of the through holes formed in the plate with holes, whereby each lens is formed into a lens array sheet.
Therefore, the optical axes of the lenses and the through holes are completely aligned with each other and no adjustment is necessary. Further, when the lens array sheets are formed on both sides of the plate with holes, the optical axes of the lenses facing each other are naturally aligned with each other, and it is not necessary to adjust them.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows an embodiment of the present invention. FIG. 1 shows an example of a manufacturing method using a photocurable resin.

First, (a) an unexposed photocurable resin 2 on one surface of the transparent flat substrate 1.
To a uniform thickness. (B) Prepare a holed plate 4 in which a plurality of cylindrical through holes 41 are arranged in parallel, for example, in the portion where a lens is formed of a light-shielding medium, and the photocurable resin layer is placed on the holed plate side. And bring them into close contact. (C) While maintaining the positional relationship between the transparent flat substrate 1 and the plate 4 with holes in parallel, the distance between the two is adjusted by the fine movement device 5. Specifically, the interval is gradually narrowed, and the photo-curable resin 2 is extruded into the through hole 41 of the plate 4 with a hole to bulge into a spherical shape to form the lens portion 31, and when the desired lens shape is obtained. Fix the distance between them. (D) In order to cure the photocurable resin from the transparent flat substrate side, ultraviolet rays are radiated using a device 6 such as a high-pressure mercury lamp to fix the lens shape, and the plate 4 with holes and the lens portion are formed. Cured resin lens array sheet 3
0 and the transparent flat substrate 1 are bonded and fixed. The resin lens array 3 is completed by the above work.

As shown in FIG. 2, before the photocurable resin 2 is applied to the transparent flat substrate 1 (a '), a release agent 7 such as a fluorine-based agent is applied, and (d') photocurable. (E) The transparent flat substrate 1 may be peeled off after the functional resin 2 is cured.

FIG. 3 shows a perspective view of a resin lens array according to the present invention. In addition, in this figure, each lens is two-dimensionally arranged four-dimensionally, but not only this example, of course,
It goes without saying that one-dimensionally arranged lenses and two-dimensionally hexagonally arranged lenses can be produced by the method of the present invention.

It is also possible to use a thermosetting resin instead of the photocurable resin, fix the gap between the transparent flat substrate 1 and the perforated plate 4, and then heat the resin in an electric furnace or the like to cure it. . It is also possible to use a resin that is cured by irradiation with X-rays. In these cases, this planar substrate need not be particularly transparent.

(Embodiment 2) FIG. 4 shows an example of a lens array in which lens array sheets are formed on both sides.
In this case, the lens array sheet may be formed on each side, or both sides may be formed simultaneously, which is more productive.

In a specific example, by adjusting the thickness d of the holed plate 4, the refractive index n of the resin layer for molding the lens, the diameter D of the through hole 41, and the radius of curvature r of the lens portion 31, a desired value can be obtained. A 1 × lens array having an angle of view 2θ and a conjugate length TC can be realized.

For example, n = 1.52, D = 1.0 mm,
At d = 9.57 mm, r = 1.66 mm, f = 3.1
9 mm, TC = 28.7 mm, and θ = 9 degrees. Similarly, at d = 4.38 mm, r = 0.76 mm, f =
1.46 mm, TC = 13.2 mm, θ = 20 degrees. Further, the resin layer 2 for molding the lens can be easily provided with a spherical lens surface by adjusting the viscosity so that the convex surface is easily formed.

When lenses are formed on both sides, the internal pressure in the through hole may rise in the lens forming step to prevent the lens from bulging in a convex shape, or the shape may deviate from the spherical surface. As described above, it is desirable to open the air vent hole 43 connecting the through holes 41 with the outside air in the plate 4 with holes. Furthermore, it is possible to reduce the pressure inside the through hole 41 through the air vent hole 43 and positively assist the lens molding.

Further, as shown in FIG. 6, after forming the lens array sheet 30 on one surface, the holed plate 4 is peeled off to form a lens array without a light shielding part, or a light shielding layer corresponding to a light shielding part is formed on the surface of the holed plate. It is also possible to apply 16 and the release agent 14 and transfer the light shielding layer to the lens portion after molding the lens.

Further, in FIG. 7, the lens array sheet is
It has a layer-stacked structure. In this case, the lens axis depends on the alignment accuracy of the through hole 41 of each holed plate 4.

In the above description, the example in which the lens array is manufactured using the flat substrate and the flat holed substrate is described. However, the lens array is formed using the curved substrate having the same curvature and the curved holed substrate. It is also possible to produce.

In the above description, the example in which a convex lens is manufactured is described, but it is also possible to manufacture a concave lens array. (A) The photocurable resin 2 is applied to one surface of the transparent flat substrate 1 to a uniform thickness. (B) A holed plate 4 having, for example, a circular through hole 41 is prepared in a portion formed of a light-shielding medium to form a lens, and the curable resin layer is brought into close contact with the holed plate side. (C) While maintaining the positional relationship between the transparent flat substrate 1 and the plate 4 with holes in parallel, the distance between the two is gradually increased by the fine movement device 5. At this time, if the viscosity of the photocurable resin 2 is adjusted to be appropriately high, a concave lens is formed on the surface of the resin layer due to the surface tension.

[0028]

According to the present invention, a lens array can be produced with extremely inexpensive manufacturing equipment and materials without using a high temperature process such as injection molding or molding and an expensive mold. Further, since the focal length can be adjusted at the interval between the flat substrate and the plate with holes, it is not necessary to change the mold or the like each time.

Further, even if the lens is not particularly aligned with the through hole of the holed plate corresponding to the light shielding portion, the axis is automatically aligned. Furthermore, even when lenses are molded on both sides, the axes of the lenses on both sides of the plate with holes and the axes of the through holes corresponding to the diaphragm automatically match, and since these three parts are adhesively fixed, there is no change over time. It never happens.

Further, a glass plate or the like is used as the transparent flat substrate, or a material such as FRP or metal is used for the plate with holes,
If the thickness and size are appropriately selected, it is possible to overcome the problem that the resin material alone is vulnerable to aging such as twisting.

Further, when a glass substrate is used for the transparent flat surface, the surface hardness is remarkably improved as compared with the case where only the resin lens layer is used, and the surface is extremely resistant to scratches and the like. When it becomes dirty, the dirt can be wiped off for cleaning.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method of forming a resin lens array on one surface using the photocurable resin according to the first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of peeling a transparent substrate after forming a resin lens array by another method according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a resin lens array according to the present invention.

FIG. 4 is a diagram illustrating a method of forming a lens array on both sides according to the present invention.

FIG. 5 is a diagram illustrating an example in which an air vent hole is provided in a plate with holes.

FIG. 6 is a diagram illustrating a method of peeling a holed plate after forming a resin lens array.

FIG. 7 is a diagram illustrating an example in which four lens array layers are stacked.

FIG. 8 is a diagram illustrating a conventional example shown in FIG. 24 of JP-A-55-90923.

FIG. 9 is a diagram for explaining the conventional example shown in FIG. 21 of JP-A-55-90923.

FIG. 10 is a diagram illustrating a conventional example of a resin gradient index lens array manufactured by polymerization.

FIG. 11 is a diagram for explaining the conventional example shown in FIG. 1 of JP-A-2-196201.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent flat substrate 2 Photocurable resin 3 (made of resin) Lens array 30 Lens array sheet 31 Lens part 32 Light-shielding film 33 Refractive index distribution type lens part 4 Plate with hole 41 Through hole 42 (filled with resin) Through hole 43 air bleeding hole 44 diaphragm 45 (functions as diaphragm) cylinder 5 fine movement device 6 ultraviolet irradiation device 7 mold release agent 8 molding die

[Procedure amendment]

[Submission date] March 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

Further, as shown in FIG. 6, after forming the lens array sheet 30 on one surface, the holed plate 4 is peeled off to form a lens array without a light shielding portion, or a light shielding film corresponding to a light shielding portion is formed on the surface of the holed plate. It is also possible to apply 32 and the release agent 7 and transfer the light shielding layer to the lens portion after the lens is molded.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025] In addition FIG. 7, a lens array sheet 3
It has a layer-stacked structure. In this case, the lens axis depends on the alignment accuracy of the through hole 41 of each holed plate 4.

Claims (12)

[Claims] Claim: What is claimed is: 1. A transparent resin is applied to one surface of a flat substrate to form a resin layer having a uniform thickness, and the surface is pressure-bonded to a holed plate made of a light-shielding material and having a plurality of through holes. Section is extruded into the through hole of the holed plate to form a lens portion, and then the resin is cured to form a lens array sheet, and the substrate and the holed plate are adhesively fixed by the resin layer. A method of manufacturing a resin lens array, comprising: 2. The method of manufacturing a resin lens array according to claim 1, wherein the substrate is a translucent substrate, the resin is a photocurable resin, and the curing step of the resin comprises the steps of: A method for manufacturing a resin lens array, which comprises irradiating ultraviolet rays from a surface of a substrate opposite to a surface on which a resin layer is formed. 3. The method for manufacturing a resin lens array according to claim 1, wherein the resin is a thermosetting resin, and the curing step of the resin is performed by heating. 4. The method for manufacturing a resin lens array according to claim 1, 2 or 3, wherein a lens array sheet is formed on both surfaces of the plate with holes. 5. The method of manufacturing a lens array according to claim 1, 2, 3 or 4, wherein the substrate has a curved surface, and at least the surface of the holed plate on the lens array sheet side has a curvature of the substrate. A method of manufacturing a resin lens array having the same curvature as the above. 6. A flat substrate is provided with a mold release agent on one surface thereof, and then a transparent resin is applied to form a resin layer to form a resin layer, and the surface is formed of a light-shielding material into a perforated plate having a plurality of through holes. After pressure bonding, a part of the resin is extruded into the through hole of the holed plate to form a lens portion, and then the resin is cured to form a lens array sheet, and then the lens array sheet and the substrate are peeled off. A method of manufacturing a characteristic resin lens array. 7. A holed plate made of a light-shielding material and having a plurality of through holes, a plurality of resin convex lenses corresponding to the through holes on a surface on the side of the through holes, and the other surface being a flat surface. A resin lens array comprising a resin lens array sheet as described in (1), and having a holed plate and a lens fixed to each other. 8. The resin lens array according to claim 7, wherein the lens array sheet is formed on a transparent flat substrate. 9. The resin lens array according to claim 7, wherein the lens array sheet has the lens array sheet on both surfaces of the holed plate having through holes. 10. The resin lens array according to claim 9, wherein the focal lengths of the respective lens elements in the two lens array sheets are the same, and the principal point for forming an erecting equal-magnification image outside the lens arrays. A resin lens array having a position. 11. The resin lens array according to claim 7, 8, 9 or 10, wherein the lens array sheet and the perforated plate are alternately stacked in multiple stages. 12. The resin lens array according to claim 8, 9, 10 or 11, wherein the lens array sheet and the perforated plate are curved surfaces.