JP4359469B2 - Lens with optical filter and manufacturing method thereof - Google Patents

Description

  The present invention relates to a lens with an optical filter. In detail, it is related with the lens for CCD which has an optical filter function, and its manufacturing method.

  Plastic lenses are lightweight and can be molded into any shape regardless of spherical or aspherical surfaces, and are therefore used in a wide range of fields such as cameras, video information equipment, copying machines, eyeglasses, and contact lenses as optical components.

Recently, in order to improve the optical performance, the lens is made aspherical, the optical design is used to make the lens multi-layered to suppress optical aberrations, and functions such as anti-reflection coating (AR coating) are provided. Has been granted. The CCD lens uses a near-infrared cut filter (IR filter) for the purpose of correcting visibility, but since the IR filter is incorporated in front of or behind the lens, the lens module becomes more complex as it becomes a high-performance lens unit. There is a tendency to become larger, which is the biggest issue in terms of space saving and cost reduction.
In addition, when AR coating or the like is performed, it is performed for each lens or filter, and further, an adjustment process of the optical axis or the like is required, which is troublesome and cost reduction is difficult.

  As a material having a conventional near-infrared cut function, there are a glass IR filter in which copper ions are contained in a special phosphate glass and an interference type glass filter. However, glass is expensive because it requires complicated steps in molding and processing, and an advantageous plastic material is desired in that respect.

  JP-A-6-118228 and JP-A-7-134209 propose an optical filter made of a synthetic resin composed of a phosphate group-containing monomer and a copper salt, and various problems of optical filters made of phosphate glass. The point has been improved. In this technology, in order to obtain an optical filter having various functions, a transparent substrate is faced, a cavity is formed around the side surface of the substrate with a gasket or the like, polymerization molding is performed in the cavity, and mold release is used. (See Patent Documents 1 and 2). However, the obtained IR filter is a material composed of a phosphate group-containing monomer, and since this material has high polarity, it has a drawback that its hygroscopic property is large and its shape changes with time.

  Japanese Patent Laid-Open No. 7-56006 proposes a two-layer hybrid lens in which a glass or plastic lens is integrally molded with a resin having a spectral adjustment function using an organic dye or the like (see Patent Document 3). In this method, since a resin layer having a spectral adjustment function is provided on the lens surface, the resin layer is on the surface in contact with the air, and has limitations in terms of hygroscopicity and lens shape transferability.

  In general, a hybrid lens in which a thin resin layer is provided on the spherical surface of the lens is manufactured by a manufacturing method called 2P (Photoreplication Process) method hybrid molding. For example, in Japanese Patent Application Laid-Open Nos. 2000-180602 and 2001-121554, a resin material is filled in a cavity portion formed of a glass or plastic lens serving as a base lens, a mold member, and a side material, and cured by ultraviolet polymerization or the like. After that, a hybrid lens is obtained through a mold release process for mold members and the like (see Patent Documents 4 and 5). In this manufacturing method, it is possible to manufacture a hybrid aspherical lens having a spectral filter function. However, since the resin layer is still outside the lens, there are problems of moisture absorption and shape transferability. In addition, since it is necessary to irradiate ultraviolet rays or the like from at least one direction, the base lens is required to have a material that efficiently transmits ultraviolet rays, and has optical characteristics that can uniformly transmit irradiation energy to the resin surface to be cured. There are restrictions on the choice of materials. Furthermore, the lens has to be released from the mold member after molding, and the manufacturing process is complicated because the lens is stressed or scratched on the lens surface. Further, it is necessary to assemble the mold member and the side frame at the time of lens molding (at the time of polymerization of the resin lens), which is inefficient in productivity.

  On the other hand, in the case of a camera optical system using a solid-state imaging device such as a CCD, an optical low-pass filter is used for the purpose of limiting the high-frequency component of the subject in order to prevent the generation of false signals that cause image degradation. As the optical low-pass filter, those using the birefringence of quartz or a plastic plate provided with a diffraction grating are used. However, quartz has low productivity and is expensive, and both the quartz plate and the plastic plate have problems that it is difficult to bond different materials.

JP-A-6-118228 JP-A-7-134209 JP 7-56006 A JP 2000-180602 A JP 2001-121554 A

  An object of the present invention is to provide a lens with an optical filter that can efficiently cut light in the near-infrared region (700 to 1000 nm) and does not affect the lens due to moisture absorption. Furthermore, the present invention is to provide a manufacturing method that achieves both space saving and cost reduction of a lens with an optical filter.

  Therefore, in order to solve the above problems, the present invention comprises a laminated structure of a surface layer portion, an intermediate layer portion, and a back layer portion, and the intermediate layer portion has an optical filter function and is blocked from outside air. A lens with an optical filter is provided.

  Further, in the present invention, the surface layer portion and the back layer portion are made of a synthetic resin, and the intermediate layer portion is made of a material different from that of the surface layer portion and the back layer portion. A lens is provided.

  The lens with an optical filter according to claim 1 or 2, wherein the surface layer portion and the back layer portion use at least one kind of synthetic resin selected from alicyclic synthetic resin and polycarbonate. Is to provide.

  Further, in the present invention, the intermediate layer part is a phosphate group-containing copolymer containing an ionic metal component mainly composed of copper ions. A lens with an optical filter is provided.

  The present invention also provides a lens with an optical filter according to any one of claims 1 to 4, wherein an optical low-pass filter function is imparted to at least one of the surface layer portion and the back layer portion. .

  Further, the present invention provides a filter material capable part in either the surface layer part or the back layer part, and the filter material acceptable part is filled with a filter material having an optical filter function, and the surface layer part and the back layer part. A method for producing a lens with an optical filter, wherein a filter material is polymerized to form an intermediate layer portion, and a surface layer portion, an intermediate layer portion, and a back layer portion are formed as an integrated lens. is there.

  Further, the present invention provides the method for producing a lens with an optical filter according to claim 6, wherein the filter material acceptable portion is integrally formed on the surface layer portion or the back layer portion by a molding process. To do.

  The lens with an optical filter according to the present invention has a laminated structure of a surface layer portion, an intermediate layer portion, and a back layer portion, and the intermediate layer portion has an optical filter function and has a configuration that is blocked from outside air. The intermediate layer portion having the optical filter function can be protected from the outside air. In particular, when the intermediate layer portion is made of a phosphoric acid group-containing resin having a near-infrared cut function, it is possible to improve wet heat resistance, which is a drawback of the phosphoric acid group-containing resin. Further, according to the manufacturing method of the present invention, since the integral molding with the optical filter function incorporated in the lens can be easily performed, there is an effect that space saving and cost reduction can be achieved.

Embodiments of the present invention will be described based on examples shown in the drawings.
As shown in FIG. 1, the lens with an optical filter according to the present invention has a laminated structure of a surface layer portion 1, an intermediate layer portion 4, and a back layer portion 3. The intermediate layer portion 4 has an optical filter function, and has an outside air. And is blocked.

  As shown in FIG. 2, the surface layer portion 1 and the back layer portion 3 are used as a mold for the filter material 2. The surface layer portion 1 is filled with the filter material 2, the back layer portion 3 is fitted to the surface layer portion 1, and the filter material 2 is polymerized and integrally molded. The filter material 2 contains a phosphate group-containing monomer and a monomer copolymerizable therewith, and a mixed unit containing an ionic metal component mainly composed of copper ions that can bind to the phosphate group. Use a mer.

At least one of the surface layer portion 1 and the back layer portion 3 shown in FIG. 1 can be provided with a diffraction grating for expressing an optical low-pass filter function.
For example, in the case of the present invention, an optical low-pass filter function can be easily obtained by forming a diffraction grating pattern in advance in the molding die and molding the surface layer portion and the back layer portion.

  The shape of the surface layer part 1 and the back layer part 3 forms the filter material acceptable part 5 in any one, and combines the other with the filter material acceptable part 5 to form the intermediate layer part 4. In the illustrated embodiment, a mold is used in which the filter material acceptable portion 5 of the surface layer portion 1 is cup-shaped and the back layer portion 3 is fitted to the filter material acceptable portion 5. Can be appropriately selected depending on the objective lens performance such as a concave or convex spherical shape or planar shape. For forming the surface layer portion 1 and the back layer portion 3, various molding methods using a mold having a desired shape can be adopted. Specifically, injection molding, compression molding, cast molding, and the like can be mentioned. Of these, injection molding is preferred. In this invention, the surface layer part 1 and the back layer part 3 are easily obtained by shape | molding in accordance with the conventional method of injection molding.

  As the surface layer portion 1 and the back layer portion 3, a material having good transparency and molding processability is used. Specifically, the synthetic resin includes at least one synthetic resin selected from polyolefin resin, acrylic resin, polycarbonate, polystyrene, alicyclic polyolefin resin, alicyclic acrylic resin, etc., among which alicyclic Of these resins and polycarbonate, alicyclic polyolefin resin is more preferable from the viewpoint of little change in shape even under high temperature and high humidity. Specific examples include ZEONEX (registered trademark) and ZEONOR (registered trademark) manufactured by ZEON CORPORATION, APPEL (registered trademark) manufactured by Mitsui Chemicals, and ARTON (registered trademark) manufactured by JSR Corporation.

The filter material 2 is included in the surface layer portion 1 and the back layer portion 3 to form the intermediate layer portion 4. The material includes a phosphate group-containing monomer, a monomer copolymerizable therewith, and a phosphate group. A mixed monomer containing an ionic metal component mainly composed of a copper ion that can be bonded to a hydrogen atom is preferable.
In general, a phosphate group-containing monomer represented by Chemical Formula 1 was used. Synthetic resins for optical filters described in JP-A-6-118228 and JP-A-7-134209 can be used.

  Specific examples of the copolymer component constituting the mixed monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl Linear, branched or cyclic alkyl (meth) acrylates such as (meth) acrylate, styrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, n-propylstyrene, i-propylstyrene, n-butyl Examples thereof include alkyl styrene such as styrene and t-butyl styrene. Furthermore, when improving the strength and adhesion of the material, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetreethylene glycol di (meth) acrylate, ethyl glycol It is also possible to use polyfunctional monomers such as di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, divinylbenzene and trivinylbenzene. it can. Furthermore, (meth) acrylic acid, (meth) acrylamide, fluoroalkyl (meth) acrylate, etc. can also be used as a copolymerization component.

Polymerization of the intermediate layer portion 4 made of the filter material 2 can be performed by general heating polymerization or ultraviolet polymerization, but a polymerization method using radiation such as electron beam or γ-ray irradiation is also possible.
Further, by introducing copper ions into the resin constituting the intermediate layer portion 4, the near infrared region portion has optical characteristics due to the interaction between the phosphate group and the copper ions. Examples of the copper compound for introducing copper ions include copper acetate, copper chloride, copper benzoate, copper formate, copper sulfate, copper nitrate, copper citrate, copper carbonate, copper pyrophosphate, and the like.

Furthermore, metal ion compounds other than copper can also be used for the purpose of dimming visible light. Specific examples include iron, cobalt, nickel, neodymium, manganese, sodium, potassium, and calcium.
The lens with an optical filter having a three-layer structure obtained by the present invention can be coated with an AR coating or the like.

  Next, examples according to the present invention will be described below, but the present invention is not limited to such examples.

  As materials corresponding to the surface layer portion 1 and the back layer portion 3 shown in FIGS. 1 and 2, ZEONEX (registered trademark) 480R manufactured by Nippon Zeon Co., Ltd. was used and molded according to a general injection molding method. The monomer mixture which is the filter material 2 constituting the intermediate layer part 4 includes 27 parts of a specific phosphate group-containing monomer represented by the following chemical formula 2 and a specific phosphate group represented by the chemical formula 3 below. It was prepared by thoroughly mixing 13 parts of the containing monomer, 30 parts of 1,6-hexanediol dimethacrylate, 29 parts of methyl methacrylate, and 1 part of α-methylstyrene. To this monomer mixture was added 17 parts of copper benzoate anhydride (copper content of 3.5 parts with respect to 100 parts of the monomer mixture), and the mixture was sufficiently dissolved by stirring and mixing at 55 ° C. Copper was uniformly dissolved. The resulting mixture was cooled at −20 ° C. for 24 hours, and free benzoic acid was separated by filtration. To this composition, 2.0 parts of t-butylperoxy (2-ethylhexanoate) was added and stirred until uniform, and a monomer mixture constituting the intermediate layer part 4 was obtained. Next, as shown in FIG. 1, the monomer mixture is contained between the surface layer part 1 and the back layer part 3 and then transferred to a polymerization tank, and the mixture is transferred to a polymerization tank at 55 ° C. for 16 hours, at 60 ° C. for 8 hours, and at 90 ° C. for 3 hours. The polymer was obtained by heating for a period of time.

  The adhesion of the three layers of the obtained polymer was good, and no bubbles or peeling were observed, and the polymer was sufficiently good as an optical filter. Moreover, when the spectral transmittance curve with the spectrophotometer of this optical filter was measured, the light of the near infrared region (700-1000 nm) was absorbed efficiently.

  Example 1 using ZEONEX (registered trademark) 480R manufactured by Nippon Zeon Co., Ltd. as the material corresponding to the surface layer part 1, and ZEONEX (registered trademark) 480R and a bisphenol A type polycarbonate blend polymer as the material corresponding to the back layer part 3 In the same manner, polymerization was carried out in the same manner with the same monomer composition as in Example 1.

  As in Example 1, the adhesion of the three layers of the obtained polymer was good, and no bubbles or peeling were observed, and the polymer was sufficiently good as an optical filter. Moreover, when the spectral transmittance curve with the spectrophotometer of this optical filter was measured, the light of the near infrared region (700-1000 nm) was absorbed efficiently.

  The material corresponding to the surface layer portion 1 is the same as in Example 1 using ZEONEX (registered trademark) 480R manufactured by Nippon Zeon Co., Ltd., and the material corresponding to the back layer portion 3 is bisphenol A type polycarbonate. Polymerization was similarly carried out with the monomer composition.

  As in Example 1, the adhesion of the three layers of the obtained polymer was good, and no bubbles or peeling were observed, and the polymer was sufficiently good as an optical filter. Moreover, when the spectral transmittance curve with the spectrophotometer of this optical filter was measured, the light of the near infrared region (700-1000 nm) was absorbed efficiently.

The material corresponding to the surface layer portion 1 and the back layer portion 3 was formed by injection molding using a die having a diffraction grating pattern in advance using ZEONEX (registered trademark) 480R manufactured by ZEON Corporation. The monomer mixture constituting the intermediate layer part 4 contains 27 parts of a specific phosphate group-containing monomer (monomer A) represented by Chemical Formula 2 and a specific phosphate group represented by Chemical Formula 3 A monomer component was prepared by thoroughly mixing 13 parts of monomer, 30 parts of 1,6-hexanediol dimethacrylate, 19 parts of methyl methacrylate, 10 parts of ethyl acrylate, and 1 part of α-methylstyrene. To this monomer component, 17 parts of copper benzoic anhydride (copper content of 3.5 parts with respect to 100 parts of the monomer mixture) was added and dissolved sufficiently by stirring and mixing at 55 ° C. Copper was uniformly dissolved. The resulting mixture was cooled at −20 ° C. for 24 hours, and free benzoic acid was separated by filtration. To this composition, 3.0 parts of Darocur 4265 (registered trademark: manufactured by Ciba Specialty Chemicals) was added and stirred until uniform to obtain a monomer mixture forming the intermediate layer part 4. Next, the monomer mixture was filled into a lens mold as shown in FIG. 1, and polymerization was performed by irradiating with an ultraviolet ray having an integrated light quantity of 20000 mj / cm ² .
As in Example 1, the adhesion of the three layers of the obtained polymer was good, and no bubbles or peeling were observed, and the functions as an optical filter such as a low-pass filter and an IR filter were sufficiently exhibited. When the obtained three-layer plastic lens was taken into a camera and a real test was performed, there was little noise due to moire patterns and the like, and an effective optical low-pass filter function was confirmed.

  Moreover, when the spectral transmittance curve with the spectrophotometer of this optical filter was measured, the light of the near infrared region (700-1000 nm) was absorbed efficiently.

(Evaluation)
Changes in the optical properties were evaluated by leaving the three-layer plastic lenses obtained in Examples 1 to 4 at a temperature of 80 ° C. and a relative humidity of 95%.

  A spectral transmission curve of the three-layer plastic lens of the present invention is shown in FIG.

Sectional drawing which shows one Example of the lens with an optical filter of this invention Sectional drawing which shows one Example of the manufacturing process of the lens with this invention optical filter Spectral transmittance curve diagram of lenses with optical filters of Examples 1, 2, 3, and 4

Explanation of symbols

1 Surface layer part 2 Filter material 3 Back layer part 4 Middle layer part 5 Filter material allowable part

Claims (1)

It consists of a surface layer part, an intermediate layer part, and a back layer part, and either the surface layer part or the back layer part is formed in a cup shape, the intermediate layer part is formed of an optical filter material, and the surface layer part or One of the back layer portions is fitted inside one of the cup shapes to block the intermediate layer portion from the outside air, and the surface layer portion and the back layer portion are made of alicyclic synthetic resin or polycarbonate. A lens with an optical filter , wherein at least one selected synthetic resin is used, and the intermediate layer portion is a phosphate group-containing copolymer containing an ionic metal component mainly composed of copper ions .

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