JP2001330709A - Shielding unit integrated microlens array and method of forming light-shielding film - Google Patents

Abstract

(57) [Abstract] (With correction) [PROBLEMS] For a microlens array manufactured by a method such as injection molding, a means for efficiently manufacturing a high-quality light-shielding-portion-integrated microlens array with excellent alignment accuracy is provided. provide. A light-shielding film is formed by discharging ink between the lenses by an inkjet method, and drying and curing the ink material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microlens array in which microlenses are arranged one-dimensionally or two-dimensionally, and more particularly to a microlens array integrated with a light-shielding portion provided with a light-shielding portion between the microlenses.

[0002]

2. Description of the Related Art In recent years, in the field of micro optics, a microlens array having a one-dimensional or two-dimensional array of microlenses having a lens diameter of several hundreds μm or less has been developed. It is expected to be used in a wide range of application fields such as multiple image transfer, optical coupler of optical fiber array, optical integrated circuit, optical system of electronic copier and facsimile, optical print head of LED or LCD printer, confocal laser microscope, etc. Or it is already in practical use in some fields.

[0003] Various reports have been made on a method of manufacturing such a microlens array. For example, (1) a method of molding plastic or glass with a mold,
(2) A lens obtained by combining a photolithography technique used in semiconductor manufacturing and the like and a hot melting method of a resist, disclosed in Micro-Optics, P.75 Taylor & Francis, 1997 and JP-A-8-313706. After patterning into a planar shape, a method of heating to a temperature higher than the softening point of the photosensitive resin to fluidize it, causing sagging of the pattern edge to obtain a convex lens, (3) JP-A-57-53702 and JP-B-4
Japanese Patent Application Laid-Open No. 34121/1991 discloses a technique for producing a flat microlens array by forming a refractive index distribution in a substrate glass by an ion exchange method.

Among them, the method (1) has high productivity and can manufacture a microlens array at the lowest cost.

[0005] The resolution of a microlens array is governed by the shape and refractive index distribution of the microlens. In an ideal microlens having no aberration, the resolution is limited by a diffraction phenomenon, and the resolution is determined by a numerical aperture and a wavelength of the microlens. In addition, light that passes through a non-lens portion where no lens is formed becomes stray light and reduces the resolution.

Here, there has been proposed a technique of forming a light shielding film on a non-lens portion to remove stray light. Examples of such a method include the following. (A) A method in which the surface roughness of a lens portion and that of a non-lens portion are made different, a resin film containing carbon particles is formed, and then only the film of the lens portion is peeled off using the difference in adhesiveness of the film ( JP-A-63-153501. (B) A method of forming a metal thin film of chromium, titanium, or the like by sputtering or the like, and then patterning by photolithography (Japanese Patent Application Laid-Open Nos. 2-64501 and 7-174).
No. 902). (C) A method of developing and removing a photosensitive black paint by a photolithography method (Japanese Patent Application Laid-Open No. 9-166701).

However, these methods have problems that not only the excellent productivity of the above (1) cannot be secured, but also that the alignment accuracy between the light-shielding film and the non-lens portion is inferior, and the lens quality is inferior.

[0008]

SUMMARY OF THE INVENTION The present invention overcomes the problems of the conventionally proposed method of forming a light-shielding film for a microlens array, responds to the high productivity of molding using a mold, and achieves high efficiency and high productivity. It is an object of the present invention to provide a light-shielding-unit-integrated microlens array having a novel structure with high quality and excellent quality, and a method for manufacturing the same.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on the method of forming a light-shielding film in a light-shielding-unit-integrated microlens array, and as a result, have adopted an ink-jet method which has not been conventionally used for this purpose. As a result, the present inventors have found that various problems that have been conventionally solved can be solved, and have completed the present invention.

That is, in order to achieve the above object, the present invention provides a microlens array comprising a plurality of microlenses formed on a transparent substrate, wherein a light-shielding film made of an ink material is formed between the lenses by an ink-jet method. It is characterized by doing.

Hereinafter, the present invention will be described in detail.

First, a method for manufacturing a microlens array will be described. The microlens array integrated with the light shielding unit of the present invention is made of a transparent polymer resin or 2P (Photo-P).
It is preferable in terms of productivity to form a plurality of microlenses by an oligomer method or by molding a glass or the like with a metal mold.

First, in the case of manufacturing with a transparent polymer resin, a thermoplastic resin such as a polycarbonate resin, an acrylic resin, an epoxy resin, and a polystyrene resin is used, and a mold for forming a microlens array shape is used. The microlens array can be manufactured by a method having high efficiency and high productivity by a known plastic molding technique such as injection molding, injection compression molding, compression molding, or the like.

Here, instead of the transparent polymer resin, quartz,
Optical glass, glass for electro-optics (alkali-free glass, etc.), translucent ceramics, or the like may be used. Also,
As a method for securing the lightness of a plastic lens and further improving heat resistance such as dimensional stability, there is a 2P molding method using an ultraviolet curable resin. In this method, a liquid resin composed of an oligomer, a monomer, or the like having a reactive double bond is supplied between a mold and a transparent substrate, and ultraviolet light is irradiated from the transparent substrate side to obtain a cured product. According to this method, a liquid material is pushed into a mold, so that the mold has excellent followability, dimensional accuracy is good, and the resin itself is excellent in heat resistance due to crosslinking.

Next, an ink material is ejected between each lens of the microlens array obtained above by an ink-jet method to form a light-shielding film. When a microlens array is provided on both surfaces, a light-shielding film may be formed only on one of the two lens surfaces.

The ink material is desirably black in terms of light-shielding properties and antireflection properties.

In the ink jet method, several picoliters (p
The printing is performed by ejecting droplets of special ink of several tens pl from l) onto a recording medium by flying from a fine nozzle (several tens of μm in diameter) onto a recording medium. Depending on the recording method, it is roughly classified into a continuous type and an on-demand type. Further, depending on the structure of the print head, there are a type in which the ink is pushed out by the vibration of the piezoelectric element, and a type in which the ink is vaporized by the heat generated by the resistive element to generate bubbles to push out the ink. The ink used is optimized for each head structure and recording method.

The inks used in the ink-jet method can be roughly classified according to the properties of the inks. Solid inks and liquid inks can be used, and any of them can be used in the microlens array integrated with the light-shielding portion of the present invention.

The solid ink is an ink which uses oily dyes, inorganic pigments, and organic pigments as coloring materials, and uses a wax which is solid at normal temperature and melts at high temperature as a solvent. This keeps the area around the head and the ink pot at a high temperature exceeding 100 ° C,
Ink is extruded in a liquid state and returns to normal temperature on a recording medium to be solidified.

On the other hand, liquid inks include aqueous inks using water-soluble dyes, inorganic pigments and organic pigments as coloring materials and water, glycerin and the like as solvents, and MEKs and alcohols using oil-soluble dyes, inorganic pigments and organic pigments as coloring materials. There is an oil-based ink using as a solvent. In addition, an ultraviolet curable ink in which a part or all of the solvent is an ultraviolet curable resin is also used.

Examples of the black coloring material that can be used in the ink include the following, but the present invention is not limited to the following.

Examples of the water-based ink include:
C. I. Direct Black 154, 168, C.I. I.
Sulfur Black 1, C.I. I. Acid Black 2,
4, 8, 51, 52, 110, 115, 156, C.I.
I. Dyes such as food blacks 1 and 2 or carbon black are exemplified. Dyes such as Solvent Black 3, 5, 46 and the like or carbon black are used as oily inks. Among them, carbon black is particularly preferred from the viewpoint of light resistance and the like.

It is desirable that the solid ink has an appropriate mechanical strength at room temperature and, on the contrary, has as low a viscosity as possible upon melting, and is required to have a characteristic of sharply melting at a constant temperature. A wax (wax) and a resin having such characteristics are used as main components, and a coloring material and, in the case of an active energy ray-curable ink, an active energy ray-curable resin polymerized and cured by an active energy ray are contained therein. .

Examples of waxes and resins include hydrocarbon oligomers (such as paraffin wax and microcrystalline wax), long-chain fatty acids (such as stearic acid and behenic acid), long-chain fatty acid esters (such as sorbitan monostearate), and long-chain fatty acids. Examples thereof include chain fatty acid amides (such as N-stearyl stearamide), long-chain alcohols (such as stearyl alcohol), polyethylene oxide, and α-olefin maleic anhydride copolymers, which are generally contained in an amount of 40 to 80% by mass.

The content of the coloring material is generally from 1 to 1
0% by mass.

The active energy ray-curable resin further contains a photopolymerization initiator as a constituent component in the case of a reactive oligomer, a reactive monomer and an ultraviolet curable resin. The content of the reactive oligomer and the reactive monomer is 10 to 40% by mass, and the content of the photopolymerization initiator is 1 to 10% by mass.

As the reactive oligomer, a photopolymerizable oligomer used for producing an ultraviolet curable resin can be used. Specific examples of the radical polymerizable oligomer include polyester (meth) acrylate, bisphenol-based epoxy (meth) acrylate, novolak-based epoxy (meth) acrylate, alkylene oxide-modified bisphenol A-based (meth) acrylate, and phosphoric acid-modified epoxy (meth) Acrylate, polycarbonate urethane (meth) acrylate, polyester urethane (meth) acrylate, polyether urethane (meth) acrylate, alicyclic urethane (meth) acrylate, aliphatic urethane (meth) acrylate, polybutadiene-modified (meth) acrylate And the like. Further, specifically, as the ion-polymerizable oligomer,
Examples include bisphenol-based epoxy resins and novolak-based epoxy resins.

As the reactive monomer, specific examples of the radical polymerizable monomer include (meth) acrylate monomers, (meth) acrylamide monomers,
Maleic ester monomers, styrene monomers,
And vinyl ether monomers. Among these, acrylic acid monomers are preferred because of their high reactivity, and more preferably contain a polyfunctional acrylate monomer having three or more acryloyl groups in the molecule.
Specific examples of the ion-polymerizable monomer include an epoxy compound having an epoxy group in a molecule, a vinyl ether-based monomer, and an oxetane compound.

The photopolymerization initiator includes a radical polymerization initiator, a cationic polymerization initiator, and an anionic polymerization initiator.
Examples of the radical polymerization initiator include acetophenone-based initiators such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin-based initiators such as benzyldimethylketal, benzophenone, and 4-benzoyl-4-methyldiphenyl. Examples thereof include benzophene-based initiators such as sulfide, thioxanthone-based initiators such as 2,4-diethylthioxanthone, α-acyloxime ester, acylphosphine oxide, benzyl, methylphenylglyoxylate, and camphorquinone. Examples of the photopolymerization initiation aid include an aliphatic alkanolamine such as triethanolamine and an aromatic amine such as ethyl 4-dimethylaminobenzoate.

In the case of a cationic polymerization initiator, a photoinitiator such as an aromatic diazonium salt, an aromatic halonium salt, an aromatic sulfonium salt, or a metallocene compound is used. Specific examples thereof include triphenylsulfonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and the like.

Examples of the anionic polymerization initiator include a combination of alkoxysilane and P-chlorophenyl-o-nitrobenzyl ether, 2-nitrobenzyl-N-cyclohexylcarbamate, and the like.

One or more of these photopolymerization initiators can be used.

In general, radical polymerization systems tend to have a higher degree of cross-linking than ionic polymerization systems and thus tend to ensure the strength of a coating film as an ink, but polymerization is inhibited by oxygen in the air. Therefore, the curability of the thin film tends to be a problem. It is very effective to cure in a nitrogen atmosphere to solve such a problem of oxygen inhibition.

The liquid water-based ink is composed mainly of water and partially uses an organic solvent in combination, and generally contains a coloring material such as a dye or pigment dissolved or dispersed therein. In addition to the color material, a viscosity adjuster, a surface tension adjuster, a pH adjuster, a humectant, and the like are added to improve the properties of the ink.

When the coloring material is a dye, it is generally not used because the use of a resin increases the viscosity of the ink.

When the coloring material is a pigment or carbon black, it is soluble in an aqueous solution in which an amine or a base is dissolved as a dispersant / binder resin, and has a weight average molecular weight of 30.
For example, a styrene-acrylic acid copolymer, a styrene-maleic acid-copolymer, or the like of from 00 to 50,000 is used. In some cases, the coloring material is completely covered with the resin and microencapsulated.

It is preferable to use an ink using a resin also from the viewpoint of the film forming property of the ink material ejected by the ink jet.

The viscosity adjusting agent is used for adjusting the viscosity of the ink, improving the ejection property of the ink, and adjusting the permeability of the ink to the recording medium. Generally, a polyalkylene glycol such as polyethylene glycol is used, and the amount of addition is 0.1 to 10% by mass. However, in the case of the present application, since the discharge is to a non-absorbing substrate such as plastic, it is preferable that the addition amount is as small as possible.

The surface tension adjusting agent is used for adjusting the surface tension of the ink, improving the ejection property of the ink, and adjusting the permeability of the ink to the recording medium. Typically,
A surfactant is used, and the amount added is 0.1 to 2% by mass. As in the case of the viscosity modifier, the addition amount is preferably as small as possible in the case of the present application.

The pH adjuster is used for keeping the pH of the ink in an appropriate state and for suppressing the dissolution / dispersion stability of the coloring material from being lowered. Generally, various acids and alkalis are used, and the amount of addition is 0.1 to 1% by mass.

As the humectant, polyhydric alcohols such as glycerin and polyethylene glycol, and pyrrolidones such as N-methyl-2-pyrrolidone are added to prevent clogging of nozzles due to drying of the ink.

In the case of a water-based active energy ray-curable ink, water-soluble among the photocurable oligomers, photocurable monomers, and photopolymerization initiators mentioned above as binders,
Used in combination considering the balance of water insolubility.

The liquid oil-based ink comprises an organic solvent as a main component, a dye or a pigment as a coloring material, a resin as a binder and / or a dispersant, a surfactant and the like. Since the organic solvent is the main component, the content of the resin can be increased as compared with the aqueous ink, so that the film forming property of the ink is good.

As organic solvents generally used, ketones such as methyl ethyl ketone, lower alcohols such as methanol and ethanol, carboxylic acid esters such as ethyl acetate, polyethylene glycol monomethyl ether acetate and ethoxyethyl propionate are used. Have been. When the coloring material is a dye, the solvent is selected in consideration of solubility, and when the coloring material is a pigment, dispersibility and dispersion stability are also taken into consideration. The content of the solvent is 20 to 95% by mass.

As the resin, a thermoplastic resin such as a phenol resin, an acrylic resin, a maleic acid resin, a rosin resin and a butyral resin is used. The resin content is generally from 1 to 30% by weight.

In the case of an oil-based active energy ray-curable ink, the above-mentioned organic solvent, a part or all of the resin may be selected from the photocurable oligomers, photocurable monomers and photopolymerization initiators described above. It is selected and used in consideration of dispersion stability.

The ink for an ink jet printer used in the present invention is prepared by mixing a solvent (water and / or an organic solvent and / or a photopolymerizable oligomer, a photopolymerizable monomer), a coloring material, and the like at a predetermined ratio, and then kneading the mixture. can do. Kneading can be performed using a disperser. Examples of the dispersing machine include a ball mill, a roll mill, and a sand mill. In the case of ink using ultraviolet rays as active energy rays,
It is preferable to mix and dissolve the photopolymerization initiator after the coloring material is sufficiently dispersed, from the viewpoint of preventing gelation of the ink.

[0048]

Next, an embodiment of the present invention will be described with reference to an example of a method for forming a light-shielding film on a microlens array using the ink jet ink prepared as described above.

First, a microlens array is manufactured by injection molding or the like using a mold for forming a microlens array shape as shown in FIG. 1 using a thermoplastic resin such as a polycarbonate resin.

Next, the black ink is discharged between the lens elements by the ink jet method, and the ink is filled between the lenses. Here, by giving the ink an appropriate fluidity, it is possible to allow the ink to naturally spread to a narrow portion between the lenses. Therefore, depending on the physical properties of the ink, etc., it is possible to optimize the leveling and fluidity of the ink by heating the substrate within an acceptable range.
In order to obtain the desired fluidity, it is preferable to use a liquid active energy ray-curable ink.

Thereafter, the ink filled between the lenses is dried and cured. As a result, a microlens array shown in FIG. 2 in which a black light-shielding film is formed between the lenses is completed. Here, in the case of a water-based or oil-based ink, the ink is dried and cured by heat energy of an oven or the like. In the case of an active energy ray-curable ink, the ink is cured by an active energy ray. If the ink is ultraviolet curable, it can be cured with a known ultraviolet curing device such as a metal halide lamp. Active energy ray-curable inks that do not contain a photopolymerization initiator can be cured with an electron beam curing device.

If the micro lens is a concave lens as shown in FIG. 3, a minute bank 5 is formed around the concave lens, and ink is ejected into the bank, as shown in FIG. A light-shielding film can be formed on the substrate.

Both the convex lens and the concave lens can form a light-shielding film by self-alignment by utilizing the shape formed by molding or the like and the fluidity of ink. The thickness of the light-shielding film depends on the light-shielding properties of the ink used, but is generally 1 to 10
It is formed with a thickness of about μm.

In the above-described microlens array integrated with a light-shielding portion of the present invention, the influence of stray light between the lenses is suppressed, a liquid crystal display device, a solid-state image sensor, multiplex image transfer by optical interconnection, and an optical fiber array optical coupler. , Optical integrated circuits, electronic systems for copiers and facsimiles, LEDs
Or it can be used in a wide range of application fields such as optical print head of LCD printer, confocal laser microscope, optical communication field, optical disc field, image display field, image transmission / coupling field, optical measurement, light sensing field, optical processing field, etc. In particular, it is extremely useful for applications requiring extremely high light-collecting characteristics and an image transfer function.

[0055]

As described above in detail, according to the microlens array integrated with the light-shielding portion and the method of forming the light-shielding film of the present invention, a high-quality (high-resolution) microlens array free from stray light can be produced with high productivity. -It can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing an example of a microlens array integrated with a light shielding unit according to the present invention.

FIG. 2 is a view A of the microlens array integrated with the light shielding unit of FIG. 1;
It is sectional drawing of A 'part.

FIG. 3 is a plan view schematically showing another example of the microlens array integrated with the light shielding unit of the present invention.

FIG. 4 is a view A of the microlens array integrated with the light shielding unit in FIG. 3;
It is sectional drawing of A 'part.

[Explanation of symbols]

 1: Convex lens 2: Ink ejection spot 3: Light shielding film 4: Concave lens 5: Embankment

Claims (7)

[Claims] 1. A microlens array comprising a plurality of microlenses formed on a transparent substrate, wherein a light-shielding film made of an ink material is provided between the microlenses by using an ink-jet method. Light-shielding unit-integrated microlens array. 2. The light-shielding-unit-integrated microlens array according to claim 1, wherein the microlens array is formed by die molding. 3. The microlens array according to claim 1, wherein the ink material is black ink. 4. The ink material according to claim 1, wherein the ink material is one of a solid ink, an oil-based ink, and a water-based ink.
4. The light-shielding-unit-integrated microlens array according to any one of Items 1 to 3. 5. The microlens array integrated with a light-shielding portion according to claim 1, wherein the ink material is an active energy ray-curable ink. 6. The microlens array of claim 5, wherein the active energy ray is an ultraviolet ray or an electron beam. 7. A light-shielding film, wherein a light-shielding film is formed with an ink material between each microlens of a microlens array having a plurality of microlenses formed on a transparent substrate by using an ink-jet method. Formation method.