JP2015191109A - Light-shielding ink, lens array, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-shielding ink that can form films within a short period and control reflectance characteristics for obtaining accurate characteristics for a light-shielding film.SOLUTION: There is provided a light-shielding ink for a lens optical element for forming a light-shielding film on the peripheral part of a lens, the light-shielding ink contains a light-shielding material shielding visible light and a light-curable material in which curing is started by irradiation of light including ultraviolet rays or heating, where the reflectance generated on the interface between the light-shielding film and the lens is made 0.1% or less.

Description

  Embodiments described herein relate generally to a light-shielding ink used for forming a light-shielding film of a lens array, a lens array, and an image forming apparatus.

  Conventionally, lens arrays have been used in image forming apparatuses such as printers, copiers, multifunction peripherals (MFPs), facsimiles, scanners, etc., or liquid crystal display devices, solid-state imaging devices, confocal laser microscopes, etc. In some cases, in order to prevent stray light, a non-lens portion is provided with a light shielding film. The application field of the lens array is not limited to the image display field, but includes an optical communication field, an optical disk field, an image transfer / combination field, an optical measurement field, an optical sensing field, an optical processing field, and the like.

  In order to form a light-shielding film on the non-lens part of the lens array, a black ink that is cured by irradiating ultraviolet rays is printed on the non-lens part, and then developed using a curing process or a photolithography method. There are ways to remove it. Further, Patent Document 1 discloses a light shielding film for an optical element, and discloses a light shielding characteristic and a refractive index control of the light shielding film.

  By the way, in the light shielding characteristics of the light shielding film formed on the lens, it is necessary to suppress the reflected light characteristics generated at the interface between the lens and the light shielding film and the reflected light characteristics generated at the surface of the light shielding film and the atmosphere to a certain amount or less. It is. In Patent Document 1, an attempt is made to control reflection characteristics by using dyes, pigments, and non-black particles as components in the light shielding film.

  However, the light-shielding paint for forming the light-shielding film containing various components does not take into consideration the coating performance for application onto the lens surface, and is insufficient for instantaneously forming the light-shielding film. . That is, in Patent Document 1, since it is a paint using a solvent, a process of drying the solvent after applying the light-shielding paint to the lens surface is essential, and time factors and non-light-shielding film formation on the lens surface are essential. There is a possibility that solvent contamination may occur in the region, and it has been difficult to apply to an optical element, for example, a lens array, which requires highly accurate optical performance.

JP 2011-186437 A

  A problem to be solved by the invention is that a light-shielding ink that can form a light-shielding film in a short time and that can control the reflectance characteristics for having precise light-shielding film characteristics, and this light-shielding ink. An object of the present invention is to provide a lens array and an image forming apparatus having a formed light shielding film.

  The embodiment is a light-shielding ink for forming a light-shielding film on the periphery of a lens, and includes a light-shielding material that shields visible light and a photocurable material that is cured by light irradiation or heating including ultraviolet light. It is a light-shielding ink for a lens optical element that contains and has a reflectance of 0.1% or less generated at the interface between the light-shielding film and the lens.

The lineblock diagram showing an example of the lens array concerning one embodiment. 1 is a configuration diagram illustrating an example of a light-shielding film forming apparatus for a lens array according to an embodiment. The block diagram which shows operation | movement of the light-shielding film forming apparatus of the lens array in one Embodiment. The block diagram which shows the example of a measurement of the reflectance of the lens array in one Embodiment. Explanatory drawing which shows schematically control of the refractive index of the light shielding film in one Embodiment. Explanatory drawing which shows the preparation example of the light-shielding ink in one Embodiment. 1 is an overall configuration diagram illustrating an example of an image forming apparatus according to an embodiment. 1 is a schematic configuration diagram illustrating an image reading unit of an image forming apparatus according to an embodiment. 1 is a schematic configuration diagram illustrating an image forming unit of an image forming apparatus according to an embodiment.

  Embodiments for carrying out the invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected about the same location.

(First embodiment)
(Lens array)
First, the configuration of the lens array of this embodiment will be described with reference to FIG. FIG. 1 is a configuration diagram of the lens array 10, (a) is a top view of the lens array 10, (b) is a cross-sectional view taken along the dashed line AA ′ in (a), and (c) is (b). It is an enlarged view which expands and shows a part of.

  As shown in FIG. 1, the lens array 10 (also referred to as a microlens array) includes, for example, a plurality of lenses 12 arranged on a transparent substrate 11. In the lens array 10, for example, a black light-shielding film 13 having a film thickness of 12 μm is formed between the lenses 12. By forming the light shielding film 13 between the lenses 12, the lens portion covered with the light shielding film 13 becomes a non-lens portion. The light shielding film 13 is formed using the light shielding ink of the present embodiment. The substrate 11 and the lens 12 are molded, for example.

  Although FIG. 1 shows an example in which the lens 12 is disposed on one side of the substrate 11, the lens 12 may be formed on both sides. The lens array 10 and the light shielding film 13 may be collectively referred to as a lens array unit.

(Formation of light shielding film)
For the formation of the light shielding film 13, for example, a light shielding film forming apparatus 20 including an inkjet head is used. In FIG. 2, the schematic block diagram of the light shielding film forming apparatus 20 is shown. As shown in FIG. 2, the light-shielding film forming apparatus 20 includes a carriage 21 that transports the lens array 10, an inkjet printing unit 22 that ejects the light-shielding ink 25, an ultraviolet irradiation unit 23, an inkjet printing unit 22, and an ultraviolet ray. A control unit 24 that controls the irradiation unit 23 is provided.

  The carriage 21 fixedly supports the lens array 10 composed of a transparent substrate 11 having a plurality of lenses 12 and moves in the arrow X direction. The transparent substrate 11 of the lens array 10 is irradiated with the position of the inkjet printing unit 22 and ultraviolet irradiation. It is conveyed to the position of the section 13.

  The control unit 24 controls the conveyance speed and conveyance timing of the conveyance table 21. When the transparent substrate 11 moves to the position of the inkjet printing unit 22, the control unit 14 controls the ejection amount of the light-shielding ink 25 from the inkjet printing unit 22, and the inkjet printing unit 22 detects each lens 12 from above the substrate 11. In the meantime, the light-shielding ink 25 is discharged.

  The ejection amount of the light-shielding ink 25 is controlled by adjusting the voltage for ejecting the ink, for example. As another control method, the amount of the light-shielding ink is controlled by adjusting the number of droplets by multi-drop printing in which a minute light-shielding ink droplet ejected from the inkjet printing unit 22 is dropped at the same position a plurality of times. It is also possible to do.

  In the case of a lens array in which the lenses 12 are arranged on both surfaces of the substrate 11, after the formation of the light-shielding film on one surface (front surface), the substrate is inverted and set on the transport table 21, and the same operation is performed. Thus, a light shielding film can be formed on the other surface (back surface).

  Next, as shown in FIG. 3, the control unit 24 transports the transport base 21 to the position of the ultraviolet irradiation unit 13, and the light shielding ink 25 applied to the lens array 10 is irradiated from the ultraviolet irradiation unit 23. Cured by ultraviolet rays 26. The control unit 24 controls the irradiation amount of the ultraviolet rays 26, the wavelength of the ultraviolet rays, and the like.

  The light-shielding film forming apparatus 20 can supply the light-shielding ink not by the inkjet method but also by application. Moreover, it is good also as an aspect which fixes the conveyance stand 21 and scans the inkjet printing part 22 and the ultraviolet irradiation part 23 with respect to the lens array 10. FIG. Alternatively, a plurality of inkjet printing units 22 and a plurality of ultraviolet irradiation units 23 may be provided. Furthermore, in order to cure the light-shielding ink 25 efficiently, the part to which the transparent substrate 11 of the transport base 21 is attached can be configured to irradiate ultraviolet rays from the back side as a glass plate, for example.

  In addition, when using the below-mentioned cation type photocurable material, efficient hardening is attained by adding a heating process after ultraviolet irradiation. The cations generated by heating after the ultraviolet irradiation are diffused, and a reactive polymerization compound such as a monomer or an oligomer can be effectively polymerized and cured. The heating temperature and heating time in the heating step can be appropriately set within a range that does not affect the lens shape of the lens array, the optical characteristics of the lens, and the like.

(Light-shielding ink)
The light shielding ink 25 used for forming the light shielding film 13 is mainly composed of a light shielding material and a photocurable material.

(Shading material)
The light shielding material is first required to have optical light shielding properties and reflection characteristics. In addition, when the ink jet printing method is used, flying performance and dispersion stability as ink characteristics are further required. Considering these characteristics, a light-absorbing pigment is used as the light-shielding material.

  Examples of such a light shielding material include carbon pigments such as carbon black and carbon nanotubes, metal oxide pigments such as iron black, zinc oxide, titanium oxide, chromium oxide, and iron oxide, and zinc sulfide. Sulfide pigments, phthalocyanine pigments, pigments composed of salts such as metal sulfates, carbonates, silicates, and phosphates, and pigments composed of metal powders such as aluminum powder, bronze powder, and zinc powder Can be mentioned. These can be used alone or in admixture of two or more.

(Photo-curing material)
The photocurable material used for the light-shielding ink 25 of one embodiment is a material that becomes a skeleton of the light-shielding film, and is a reactive polymerizable compound having a polymerizable functional group, a reactive polymerizable compound that polymerizes with light, such as an oligomer, It consists of a photoinitiator that initiates these polymerizations.

A wide variety of reactive polymerization compounds are currently used for various purposes, and can be roughly classified into radical types and cationic types according to polymerization modes.

  The radical type is typically an acrylic monomer / oligomer having an acryloyl functional group, and polymerization is accelerated by radicals generated from a photoinitiator irradiated with light. Disadvantages include oxygen inhibition during radical polymerization and relatively large volume shrinkage after curing.

  On the other hand, the cation type includes cyclic ether compounds typified by epoxy and oxetane compounds, vinyl ether compounds having a vinyl ether group, and the like. Light that initiates polymerization using proton generation by light irradiation as a photoinitiator. It is an acid generator. Among these, the cyclic ether compound is characterized by low volume shrinkage after polymerization and, accordingly, excellent adhesion to the substrate. Cationic polymerization is different from radical type in that it can be polymerized without causing oxygen inhibition and has an excellent ability to form a thin film.

  As the light-shielding film 13 for the lens array 10, in consideration of the above-described characteristics, a material having both ink characteristics as the light-shielding ink 25 by the ink jet method can be appropriately selected. That is, the material used for the light-shielding ink 25 according to one embodiment is a light-shielding property, a reflective property, a cured film strength, a UV-curing condition, a property such as a viscosity, a surface tension, etc. There is no particular limitation as long as it can satisfy the dispersion stability and compatibility with the head member.

  Radical type reactive polymer compounds are represented by monomers such as monofunctional acrylates, bifunctional acrylates, 3 or more polyfunctional acrylates, polyester acrylates, urethane acrylates, epoxy acrylates, etc., depending on the number of acryloyl groups in the molecule. The oligomer which can be illustrated can be illustrated.

  Among these, a monofunctional monomer is often used as a reactive diluent and plays an important role as a viscosity adjusting material for an inkjet ink. Specifically, for example, isobonyl acrylate, acryloyl morpholine, dicyclopentadienyl acrylate, acrylic acid adduct of phenyl glycidyl ether, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxy Examples thereof include hexyl acrylate, ethyl carbitol acrylate, tetrahydrofurfuryl acrylate, 2-acryloyloxyethyl phthalate, and benzyl acrylate, and methacrylic acrylates such as 2-hydroxyhexyl methacrylate, allyl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate. In addition to acrylics, N-vinyl pyrrolidone, N-vinyl caprolactam, etc. are also useful as diluents.

  Examples of the bifunctional acrylate include neopentyl glycol diacrylate, nonanediol diacrylate, tripropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, and EO adduct acrylate of bisphenol A. Examples of the polyfunctional acrylate include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and triacrylate of isocyanuric acid EO adduct.

  Examples of the cationic reactive polymerization compound include alicyclic epoxy compounds, oxetane compounds, vinyl ether compounds, and the like.

  As the alicyclic epoxy compound, an epoxy group is bonded to one or both of a hydrocarbon group having a divalent aliphatic skeleton or an alicyclic skeleton, or a divalent group having an aliphatic chain or alicyclic skeleton in part. And compounds having an alicyclic epoxy group.

  Specifically, for example, a cyclomer that is a (meth) acrylate compound having an alicyclic epoxy compound or an epoxy group exemplified by Daicel Chemical Company's Celoxide 2021, Celoxide 2021A, Celoxide 2021P, Celoxide 2081, Celoxide 2000, and Celoxide 3000. A200, cyclomer M100, MGMA (methyl glycidyl methacrylate), glycidol which is a low molecular weight epoxy compound, β-methyl epichlorohydrin, α-pinene oxide, α-olefin monoepoxide having 12 to 14 carbon atoms, α having 16 to 18 carbon atoms -Olefin monoepoxide, epoxidized soybean oil such as Daimac S-300K, epoxidized linseed oil such as Daimac L-500, Epolide GT301, Epolide GT401 Una polyfunctional epoxy, and the like.

  Furthermore, a cycloaliphatic epoxy compound of US Dow Chemical, such as Cyracure, a compound in which the hydroxyl terminal of a hydrogenated and aliphaticized low molecular phenol compound is replaced with a group having an epoxy, ethylene glycol, glycerin, Examples include glycidyl ether compounds such as polyhydric aliphatic alcohols / alicyclic alcohols such as neopentyl alcohol, hexanediol, and trimethylolpropane, hexahydrophthalic acid, and glycidyl esters of hydrogenated aromatic polycarboxylic acids. . These alicyclic epoxy compounds may be used alone or in combination of two or more.

  Examples of oxetane compounds include (di [1-ethyl (3-oxetanyl)] methyl ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, [(1-ethyl-3-oxetanyl) methoxy] cyclohexane. A compound in which one or more oxetane-containing groups are introduced into an alicyclic ring such as bis [(1-ethyl-3-oxetanyl) methoxy] cyclohexane or bis [(1-ethyl-3-oxetanyl) methoxy] norbornane, ethylene glycol And an ether compound obtained by dehydrating condensation of an oxetane-containing alcohol such as 3-ethyl-3-hydroxymethyloxetane to an aliphatic polyhydric alcohol such as propylene glycol or neopentyl alcohol.

  Examples of the oxetane compound containing an aromatic skeleton include 1,4-bis ((1-ethyl-3oxetanyl) methoxy) benzene, 1,3-bis ((1-ethyl-3oxetanyl) methoxy) benzene, 4 , 4′-bis ((3-ethyl-3oxetanyl) methoxy) biphenyl, phenol novolac oxetanes and the like. These oxetane compounds may be used alone or in combination of two or more.

  Examples of vinyl ether compounds include 2-ethylhexyl vinyl ether, butanediol divinyl ether, cyclohexane dimethanol divinyl ether, cyclohexane dimethanol monovinyl ether, diethylene glycol monovinyl ether, diethylene glycol divinyl ether, hexanediol divinyl ether, triethylene glycol divinyl ether. Examples include 4-hydroxybutyl vinyl ether. These vinyl ether compounds may be used alone or in combination of two or more.

(Photopolymerization initiator)
Examples of the photopolymerization initiator include radical systems and cationic systems, which can be appropriately selected depending on the reactive polymerization compound to be blended. Examples of the radical system include benzoin ether system, acetophenone system, and phosphine oxide system, such as 1-hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Examples include a cleavage type such as benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and a hydrogen abstraction type such as benzophenone, 2,4-diethylthioxanthone, and isopropylthioxanthone.

  Examples of the cationic system include onium salts, diazonium salts, quinonediazide compounds, organic halides, aromatic sulfonate compounds, bisulfone compounds, sulfonyl compounds, sulfonate compounds, sulfonium compounds, sulfamide compounds, iodonium compounds, sulfonyldiazomethane compounds, and their compounds. Mixtures and the like can be used.

  Specifically, for example, triphenylsulfonium triflate, diphenyliodonium triflate, 2,3,4,4-tetrahydroxybenzophenone-4-naphthoquinone diazide sulfonate, 4-N-phenylamino-2-methoxyphenyldiazonium Sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium p-ethylphenyl sulfate, 4-N-phenylamino-2-methoxyphenyldiazonium 2-naphthyl sulfate, 4-N-phenylamino-2-methoxy Phenyldiazonium phenylsulfate, 2,5-diethoxy-4-N-4'-methoxyphenylcarbonylphenyldiazonium-3-carboxy-4-hydroxyphenylsulfate, 2-methoxy-4-N-phenylsulfate Cycloalkenyl diazonium 3-carboxy-4-hydroxyphenyl sulfate, diphenyl sulfonyl methane, diphenyl sulfonyl diazomethane, diphenyl disulfone, alpha-methyl benzoin tosylate, pyrogallol mesylate, and the like benzoin tosylate.

(Photosensitizer)
As a photosensitizer, the anthracene diether compound represented, for example by following General formula (1) is mentioned.

(In the formula, R ³ represents a monovalent organic group having 1 to 5 carbon atoms, and R ⁴ and R ⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkylsulfonyl group, or an alkoxy group. Represents a group.)
In the general formula (2), examples of the monovalent organic group that can be introduced as R ³ include an alkyl group, an aryl group, a hydroxyalkyl group, an alkoxyalkyl group, an allyl group, a benzyl group, and a vinyl group. .

  Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, and an i- Examples include a pentyl group.

  Examples of the aryl group include a phenyl group, a biphenyl group, an o-tolyl group, an m-tolyl group, and a p-tolyl group.

  Moreover, as a hydroxyalkyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 2-methyl-2-hydroxyethyl group, 2-ethyl-2-hydroxyethyl group etc. are mentioned, for example.

  Examples of the alkoxyalkyl group include a 2-methoxyethyl group, a 3-methoxypropyl group, a 2-ethoxyethyl group, and a 3-ethoxypropyl group.

  Moreover, as an allyl group, 2-methylallyl group etc. are mentioned, for example. Compounds having such a group are disclosed in, for example, J. Org. Am. Chem. Soc. , Vol. 124, no. 8, 1590 (2002).

In addition, R ⁴ and R ⁵ are not particularly limited as long as they are represented in the formula, but in consideration of the ease of synthesis, both are preferably hydrogen atoms.

  Specific examples of the compound represented by the general formula (2) include 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 2-ethyl-9,10-diethoxyanthracene, dialkoxyanthracene such as 2,3-diethyl-9,10-diethoxyanthracene, 9,10-diphenoxyanthracene, 9,10-diallyloxyanthracene, 9, Examples include 10-di (2-methylallyloxy) anthracene, 9,10-divinyloxyanthracene, 9,10-di (2-hydroxyethoxy) anthracene, and 9,10-di (2-methoxyethoxy) anthracene.

  Any of these compounds exhibits a sufficient effect, but in consideration of the cost of obtaining the compound or its synthesis raw material and the safety of the compound, 9,10-dibutoxyanthracene and 9,10-divinyloxy Anthracene is particularly preferred.

  The content of such a photosensitizer depends on the type of compound used, but generally, if it is blended at a ratio of about 10 to 50% by weight with respect to the photoacid generator, The effect can be demonstrated.

  Moreover, the light-shielding ink of this embodiment can use a polymerization inhibitor as needed. Polymerization inhibitors include cationic and radical systems. Examples of the cationic system include n-hexylamine, dodecylamine, aniline, dimethylaniline, diphenylamine, triphenylamine, diazabicyclooctane, diazabicycloundecane, 3-phenylpyridine, 4-phenylpyridine, lutidine, and 27-di. -T-butylpyridine and the like.

  The radical system includes DPPH (1,1-diphenyl-2-picrylhydrazyl), TEMPO (2,27,6-tetramethylpiperidinyl-1-oxyl), p-benzoquinone, chloranil, nitrobenzene, hydroquinone ( HQ), methylhydroquinone (MEHQ), t-butylcatechol, dimethylaniline and the like.

(Preparation of light-shielding ink)
In order to prepare a light-shielding ink using these materials, a dispersion step in which a light-shielding material is dispersed in a monomer in advance, a reactive polymerization compound such as an appropriate monomer and oligomer in the obtained dispersion, and a photoacid generator, Furthermore, if necessary, after adding a mixing agent such as a sensitizer and a polymerization inhibitor and mixing and stirring, a purification step such as filtration or centrifugation to finally remove coarse particles and unnecessary solids is performed. This is an ultraviolet curable light-shielding ink.

  In the dispersion step, a dispersant can be added as necessary to enhance the dispersibility of the shielding material. Examples of the dispersant include a dispersant such as a nonionic surfactant and an ionic surfactant, and a polymer dispersant.

(Application by dispenser)
In addition, as a method of applying the light shielding film 13 and the lens portion material in order to form the lens array 10 of the present embodiment, it can be performed by applying a trace amount liquid by a disperser. For example, a non-contact jet dispenser (Cyber Jet 2) manufactured by Musashi Engineering Co., Ltd., a micro dispenser manufactured by Hyojin Equipment Co., Ltd. (Heisin Micro Dispenser), a micro dispenser manufactured by Micro Drop Technology Co., Ltd. (nano jet), or the like can be used. . A lens structure is formed by applying a predetermined amount of light-shielding ink or lens part material liquid on the lens substrate using these, curing immediately after application, and repeating application and curing.

(Measurement of reflectance)
For the measurement of reflectance, a measurement sample is first prepared. The sample is the same material as the resin material used for the lens, and a block-shaped sample and light-shielding ink is applied to one side of the sample, and a necessary curing process is performed to form a cured film.

  The reflectance is measured with the configuration shown in FIG. 4 includes a laser light source 27, a laser light amount detector 28, a lens sample block 110, and a light-shielding ink 130. As the laser light source 27, SIGMA KOKI LDU33-5V was used. The laser light quantity detector 28 is an Advantest optical power meter Q8230. Laser light is irradiated on the side surface of the sample block 110 from the laser light source 27 at a predetermined angle, and the laser light output by reflecting the light-shielding ink 130 coating surface is detected by the detector 28.

  The ratio of the amount of light detected by the detector 28 when the light-shielding ink 130 was applied to the amount of light detected by the detector 28 in the sample block 110 where the light-shielding ink 130 was not applied was defined as the reflectance. In the sample block 110 to which the light-shielding ink 130 is applied, when the light amount of the detector 28 is zero, the reflectance is 0% and the laser light is completely absorbed.

(Control of refractive index)
Several material methods for adjusting the refractive index of the light-shielding film are listed. The mechanical skeleton of the light-shielding film is formed by a curable resin such as a monomer or oligomer, and the refractive index varies depending on the type. It becomes possible to adjust to a desired refractive index by blending monomers having different refractive indexes.

  In addition, there is a method in which metal oxide fine particles (inorganic oxide fine particles) having a high refractive index such as titanium oxide and zirconium oxide are dispersed in a resin. When metal oxide fine particles are used, the refractive index can be adjusted by the content of the fine particles, but it is required to make the particles fine and to make the dispersion characteristics uniform. Furthermore, it is possible to introduce sulfur, halogen, aromatic rings, etc. having high atomic refraction into the resin structure by devising the resin itself.

  FIG. 5 is an explanatory diagram schematically showing control of the refractive index of the light shielding film. FIG. 5A shows an example in which the light shielding film 13 contains carbon black (B) as a light shielding material. In FIG. 5A, when both the refractive indexes of the lens substrate 11 and the light shielding film 13 are the same, the light is transmitted. However, if the refractive indexes of the two are different, the light entering the lens substrate 11 is transmitted to the lens substrate 11. And reflected at the interface between the light shielding film 13 (reflected light is indicated by a dotted line).

  FIG. 5B is an example in which the light shielding film 13 includes carbon black (B) as a light shielding material and inorganic oxide particles (C) as a refractive index adjusting agent. Since the refractive index adjusting agent is contained, the light incident on the light shielding film 13 is absorbed by the carbon black (B) and is not reflected. The inorganic oxide particles (C) are, for example, titanium oxide.

  Hereinafter, a specific example of the light-shielding ink 25 of the present embodiment will be shown and described in detail.

[Preparation of light shielding material dispersion]
The light shielding material, the dispersing agent, and the reactive polymerization compound as a solvent component shown below were mixed to obtain mixed liquids having different blending ratios of the light shielding material. A carbon black pigment was used as a light shielding material.

・ Light shielding material (carbon black pigment) 20.0% by weight
・ Dispersant (Abyssia Solsperse 32000) 5.5% by weight
・ Dispersant (Abyssia Solsperse 22000) 0.7% by weight
-Reactive polymerization compound (TEGDVE) 73.8% by weight
(TEGDVE: Triethylene glycol divinyl ether)
Each of the obtained mixed liquids was filled in a circulating sand mill with 0.5 mm diameter beads, and subjected to a dispersion treatment for about 1 hour. After the dispersion treatment, coarse particles were removed using a filter having a pore diameter of 5 μm to obtain a carbon black pigment shading material dispersion. In this embodiment, since the inkjet ink is taken as an example, the processing by the filter was performed in order to reduce the average particle size and sharpen the particle size distribution. Processing may be omitted.

[Preparation of light-shielding ink]
A reactive polymerization compound, a photoacid generator, and a sensitizer were blended in the prepared light-shielding dispersion, and the mixture was stirred for about 1 hour using a stirrer such as a honogenizer. The obtained mixed solution was filtered through a 5 μm membrane filter, whereby ink Nos. Having different reactive polymerization compound contents were used. 1-No. 8 was prepared. In addition, when producing a lens by methods other than the ink application by inkjet, the process after filtration can be omitted. FIG. 1-No. 8 shows the blending ratio of each ink. FIG. 6A shows the blending ratio including the light shielding material dispersion, and the dispersant was included in TEGDVE (reactive polymerization compound).

In FIG. 6 (a), an epoxy resin monomer manufactured by Daicel Corp. is used as the reactive polymerization compound C2021, dibutoxyanthracene manufactured by Kawasaki Kasei Co., Ltd. is used as the sensitizer DBA, and titanium oxide as a refractive index adjusting agent is used. Aldrich's Cas. 1317-70-0 was used.

  A light-shielding ink prepared according to the formulation of FIG. 6A is applied to a block sample for reflectance measurement with a bar coder, and UV irradiation treatment is performed using a HOYA UV irradiation device (H-8LH4) to form a light-shielding film. did. When the reflectance was measured using the prepared sample, the result shown in FIG. 6B was obtained. No. 1-No. 6 and no. In the case of ink No. 8, the reflectance could be 0.1 or less.

  The refractive indices of TEGDVE and C2021 are expected to be TEGDVE <C2021. It can be confirmed that a minute adjustment of the refractive index is possible by controlling the blending ratio of TEGDVE and C2021. No. which does not contain C2021. The ink of No. 7 had a high reflectance, and its optical characteristics deteriorated when a light shielding film was formed on an actual lens.

  Further, from the results of the inks (No. 4-No. 6, No. 8), it was confirmed that the refractive index could be adjusted using titanium oxide fine particles.

(Image forming device)
FIG. 7 is a configuration diagram of an image forming apparatus which is an example of an optical apparatus using the lens array 10 according to the embodiment.

  As shown in FIG. 7, the image forming apparatus 100 includes a scanner unit 30 that reads an image such as a document, a printer unit 40 that processes image data generated by the scanner unit 30 and forms an image on a sheet, and a printer. The unit 40 includes a paper feeding unit 70 that feeds paper.

  The scanner unit 30 is provided on the upper part of the image forming apparatus 100, reads a document sent by the automatic document feeder 31 or a document placed on the document table 32, and generates image data. It has.

  FIG. 8 is an enlarged sectional view showing the image sensor 33 of the image reading unit. The image sensor 33 is a one-dimensional sensor arranged in the main scanning direction (the depth direction in FIGS. 7 and 8) and has a housing 34. The housing 34 is disposed on a substrate 35, and light sources (light emitting elements) 36 and 37 for irradiating light in the direction of the document are provided on the upper surface of the housing 34 on the document table 32 side so as to extend in the main scanning direction. Yes.

  Examples of the light sources 36 and 37 include an LED, a fluorescent tube, a xenon tube, a cold cathode tube, and an organic EL. The lens array 10 is supported between the light sources 36 and 37 at the top of the housing 34, and a sensor 38 made up of a CCD or CMOS is mounted on the substrate 35 at the bottom of the housing 34.

  The light sources 36 and 37 irradiate the image reading position of the document on the document table 32, and the light reflected at the image reading position enters the lens array 10. The lens array 10 functions as an erecting equal-magnification lens, and light incident on the lens array 10 is emitted from the exit surface of the lens array 10 and forms an image on the sensor 38. The imaged light is converted into an electrical signal by the sensor 38, and the electrical signal is transferred to a memory unit (not shown) of the substrate 35.

  The printer unit 40 is provided at the center of the image forming apparatus 100. For example, the image forming units 41Y, 41M, 41C for yellow (Y), magenta (M), cyan (C), and black (K) are provided. 41K and an exposure apparatus 50 having scanning heads 51Y, 51M, 51C, 51K corresponding to these image forming units. The image forming units 41Y, 41M, 41C, and 41K are arranged below the intermediate transfer belt 42 in parallel from upstream to downstream.

  FIG. 9 is an enlarged configuration diagram illustrating the image forming unit 41K among the image forming units 41Y, 41M, 41C, and 41K. In the following description, the image forming units 41Y, 41M, 41C, and 41K have the same configuration, and therefore the image forming unit 41K will be described as a representative.

  As shown in FIG. 9, the image forming unit 41K includes a photosensitive drum 43K that is an image carrier. Around the photosensitive drum 43K, a charging charger 44K, a developing device 45K, a primary transfer roller 46K, a cleaner 47K, a blade 48K, and the like are arranged along the rotation direction t. The exposure position of the photosensitive drum 43K is irradiated with light from the scanning head 51K, and an electrostatic latent image is formed on the photosensitive drum 43K.

  The charging charger 44K uniformly charges the entire surface of the photosensitive drum 43K. The developing device 45K supplies a two-component developer containing black toner and a carrier to the photosensitive drum 43K by a developing roller to which a developing bias is applied. The cleaner 47K uses the blade 48K to remove residual toner on the surface of the photosensitive drum 43K.

  Next, the configuration of the scanning head 51K of the exposure apparatus 50 will be described. The scanning head 51K faces the photosensitive drum 43K. The photoconductor drum 43K rotates at a preset rotation speed and can store charges on the surface. The photoconductor drum 43K is exposed to light from the scanning head 51K and exposed to light, and the surface of the photoconductor drum 43K is statically exposed. An electrostatic latent image is formed.

  The scanning head 51K has a lens array unit 10K, and the lens array unit 10K is supported by a holding member 52K. The holding member 52K has a support 53K at the bottom, and a light emitting element 54K as a light source such as an LED is disposed on the support 53K. The light emitting elements 54K are linearly arranged at equal intervals in the main scanning direction.

  In addition, a substrate (not shown) including a driver IC that controls light emission of the light emitting element 54K is disposed on the support 53K. The drive IC constitutes a control unit, generates a control signal for the scanning head 51K based on the image data, and causes the light emitting element 54K to emit light with a predetermined light amount according to the control signal. The light beam emitted from the light emitting element 54K enters the lens array unit 10K, passes through the lens array unit 10K, forms an image on the photosensitive drum 43K, and an image is formed on the photosensitive drum 43K. Also, a cover glass 55K is attached to the upper part (outgoing side) of the scanning head 51K.

  As shown in FIG. 7, a toner cartridge 49 that supplies toner to the developing devices 45Y, 45M, 45C, and 45K is provided above the image forming units 41Y, 41M, 41C, and 41K. The toner cartridge 49 includes toner cartridges 49Y, 49M, 49C, and 49K for each color of yellow (Y), magenta (M), cyan (C), and black (K).

  The intermediate transfer belt 42 moves cyclically. The intermediate transfer belt 42 is stretched around the driving roller 61 and the driven roller 62. Further, the intermediate transfer belt 42 is opposed to and contacts the photosensitive drums 43Y, 43M, 43C, and 43K. A primary transfer voltage is applied by a primary transfer roller 46K to a position of the intermediate transfer belt 42 facing the photosensitive drum 43K, and the toner image on the photosensitive drum 43K is primarily transferred to the intermediate transfer belt 42.

  A secondary transfer roller 64 is disposed opposite to the driving roller 61 that stretches the intermediate transfer belt 42. When the sheet S passes between the driving roller 61 and the secondary transfer roller 64, a secondary transfer voltage is applied to the sheet S by the secondary transfer roller 64. The toner image on the intermediate transfer belt 42 is secondarily transferred to the paper S. A belt cleaner 65 is provided near the driven roller 62 of the intermediate transfer belt 42.

  The paper feed unit 70 includes a plurality of paper feed cassettes 71 that accommodate various sizes of paper. Between the paper feed cassette 71 and the secondary transfer roller 64, a transport roller 72 for transporting the paper S taken out from the paper feed cassette 71 is provided. Further, a fixing device 66 is provided downstream of the secondary transfer roller 64.

  Further, a conveyance roller 73 is provided downstream of the fixing device 66. The conveyance roller 73 discharges the paper S to the paper discharge tray 74. Further, a reverse conveyance path 75 is provided downstream of the fixing device 66. The reverse conveyance path 75 reverses the paper S and guides it in the direction of the secondary transfer roller 64, and is used when performing duplex printing.

  According to the embodiment described above, it is possible to provide a light-shielding ink capable of forming a light-shielding film in a short time and controlling the reflectance characteristics for having precise light-shielding film characteristics. . In addition, it is possible to provide a lens array and an image forming apparatus having a light shielding film formed of the light shielding ink.

  In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof as well as included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 10 ... Lens array 11 ... Transparent substrate 12 ... Lens 13 ... Light-shielding film 100 ... Image forming apparatus 30 ... Scanner part 33 ... Image sensor 50 ... Exposure apparatus 51Y, 51M, 51C, 51K ... Scanning head

Claims (5)

A light-shielding ink for forming a light-shielding film on the periphery of the lens,
It contains a light-shielding material that shields visible light and a photo-curing material that begins to be cured by light irradiation or heating including ultraviolet light, and the reflectance generated at the interface between the light-shielding film and the lens is 0.1% or less. Light-shielding ink for lens optical elements.   Furthermore, the light-shielding ink of Claim 1 which controls the refractive index of the said light shielding film by mix | blending inorganic oxide particle | grains.   The light-shielding ink according to claim 2, wherein the inorganic oxide particles are titanium oxide or zirconium oxide. A plurality of lenses formed on a transparent substrate;
A light-shielding film formed of a light-shielding ink around the plurality of lenses,
The light-shielding ink contains a light-shielding material that shields visible light and a photo-curing material that is cured by light irradiation or heating including ultraviolet rays, and has a reflectivity of 0 at the interface between the light-shielding film and the lens. Lens array characterized by being 1% or less. A light source that emits light;
The lens array according to claim 4, wherein light emitted from the light source passes through;
An image forming apparatus.

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