JP5741347B2 - Optical filter and imaging apparatus using the same - Google Patents

Description

  The present invention relates to an optical filter and an imaging device using the same.

  In an imaging device using a solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor), various optical systems are used to reproduce the color tone and obtain a clear image. A filter (optical filter) having a specific function is disposed between the imaging lens and the solid-state imaging device. A typical example is a filter (near-infrared cut filter) that blocks light in the near-infrared wavelength region in order to correct the spectral sensitivity of a solid-state image sensor to human visibility. It arrange | positions between image sensors. In addition, the imaging device adjusts the amount of incoming light to prevent the imaging device from saturating the charge generated by light reception and preventing imaging, and the optical members such as lenses and sensors in the imaging device and the like. In order to cut off stray light due to reflection or scattering from the holding member or the like, a shielding member called a diaphragm is disposed.

  In recent years, image pickup apparatuses using solid-state image pickup elements have been miniaturized and have been mounted on small electronic devices such as mobile phones. Recently, there has been an increasing demand for downsizing and higher functionality of such electronic devices themselves, and accordingly, further downsizing of imaging devices is also required.

  As a method for realizing downsizing of an imaging apparatus, for example, a method of integrally providing a black coating functioning as a diaphragm on an optical filter is known (see, for example, Patent Document 1). This method eliminates the need for a space for disposing the diaphragm, and can reduce the size of the apparatus. In addition, the number of parts can be reduced and the assembly process can be simplified.

  By the way, although the said black coating is formed in a required pattern by the photolithographic method in the outer edge part of the optical filter surface, there existed a problem that formation took time.

JP 2002-268120 A JP-A-60-139757

  An object of the present invention is to provide an optical filter having an aperture function and excellent in productivity, and a highly reliable imaging apparatus using such an optical filter.

An optical filter according to an aspect of the present invention is an optical filter used in an imaging device including an imaging element into which light from a subject or a light source is incident, and is disposed between the subject or the light source and the imaging element. A light-blocking part that is formed integrally with a photocurable resin on at least one surface of the filter body that is transparent to the incident light and that is incident on the image sensor. The optical filter body is provided with a functional layer that reflects light that cures the photocurable resin, the surface of the functional layer is flat, and the light shielding layer is in contact with the surface. The functional layer is provided as a light reflecting film made of a dielectric multilayer film .

An optical filter according to another aspect of the present invention is an optical filter used in an imaging device including an imaging element into which light from a subject or a light source is incident, and is provided between the subject or the light source and the imaging element. A filter body that is arranged and transparent to the incident light, and is a light-shielding material that is integrally patterned by photolithography on at least one surface of the optical filter body and blocks a part of the light incident on the image sensor A functional layer that reflects light used for the photolithography is provided on the optical filter body, the surface of the functional layer is flat, and the light shielding layer is provided in contact with the surface, The functional layer is a light reflecting film made of a dielectric multilayer film .

  An imaging device according to another aspect of the present invention includes an imaging device on which light from a subject or a light source is incident, a lens disposed between the subject or the light source and the imaging device, the subject or the light source, and the imaging. It is characterized by comprising the above optical filter disposed between the elements.

  According to the present invention, an optical filter having a diaphragm function and excellent in productivity is provided. In addition, according to the present invention, a highly reliable imaging apparatus including such an optical filter is provided.

It is sectional drawing which shows the optical filter of the 1st Embodiment of this invention. It is sectional drawing explaining the formation method of the light shielding layer of the optical filter shown in FIG. It is a graph which shows the change of the hardening characteristic of photocurable resin by the presence or absence of an ultraviolet-infrared-light reflection film. It is a top view of the optical filter shown in FIG. It is a top view which shows the modification of the 1st Embodiment of this invention. It is sectional drawing which shows the modification of the 1st Embodiment of this invention. It is sectional drawing which shows the optical filter of the 2nd Embodiment of this invention. It is sectional drawing which shows the optical filter of the 3rd Embodiment of this invention. It is sectional drawing explaining the formation method of the light shielding layer of the optical filter shown in FIG. It is sectional drawing which shows schematically the imaging device of the 4th Embodiment of this invention. It is a figure which shows the absorption spectrum of the infrared rays absorption pigment | dye used in one Example of this invention. It is a figure which shows the spectral transmittance curve of each near-infrared cut off filter of Example 1 and 2 of this invention.

  Embodiments of the present invention will be described below. In addition, although description is demonstrated based on drawing, those drawings are provided for illustration and this invention is not limited to those drawings at all.

(First embodiment)
FIG. 1 is a cross-sectional view schematically showing a near-infrared cut filter according to the first embodiment of the present invention.

  As shown in FIG. 1, a near-infrared cut filter 100 of the present embodiment is integrally formed with a near-infrared cut filter main body (hereinafter simply referred to as “filter main body”) 10 and an outer peripheral portion of one main surface thereof. A light shielding layer 20.

  The filter body 10 is formed on the transparent base material 11 and one main surface of the transparent base material 11 and transmits light in the visible wavelength region but reflects light in the ultraviolet wavelength region and the infrared wavelength region. An ultraviolet / infrared light reflection film 12 made of a multilayer film, and an antireflection film 13 formed on the other main surface of the transparent substrate 11.

  Further, the light shielding layer 20 contains an inorganic or organic colorant such as carbon black or titanium black, and is cured by light in the ultraviolet wavelength region or the like. It is formed on the main surface on the light reflecting film 12 side. Here, “light shielding” refers to a property of blocking light transmission mainly by absorbing light. The light shielding layer 20 made of a photocurable resin having such a light shielding property is used as an imaging element when the near-infrared cut filter 100 of the present embodiment is used in an imaging device incorporating an imaging element as described later. It functions as a so-called stop that adjusts the amount of incident light or cuts stray light. The thickness of the light shielding layer 20 is not particularly limited, but is preferably in the range of 0.003 to 30 μm and more preferably in the range of 0.01 to 10 μm from the viewpoints of downsizing and light shielding properties of the imaging device.

The light shielding layer 20 can be formed, for example, as shown in FIG.
First, the photocurable resin 20A having a light shielding property is applied to the entire surface of the ultraviolet / infrared light reflecting film 12 of the filter body 10 (FIG. 2A). The photocurable resin is not particularly limited as long as it has light shielding properties and can be cured by light in at least the ultraviolet wavelength region. As a photocurable resin coating method, spin coating method, bar coating method, dip coating method, casting method, spray coating method, bead coating method, wire bar coating method, blade coating method, roller coating method, curtain coating method, A slit die coating method, a gravure coating method, a slit reverse coating method, a micro gravure method, a comma coating method and the like can be used. The application may be performed in a plurality of times. Further, in order to improve adhesion to the ultraviolet / infrared light reflecting film 12 prior to coating, the surface of the ultraviolet / infrared light reflecting film 12 may be subjected to a coupling treatment with hexamethyldisilazane (HMDS) or the like. Good.

  Next, the light L is irradiated to the photocurable resin 20A through the photomask 14 having an opening corresponding to the light shielding layer 20 (FIG. 2B). For example, if the light curable resin 20A is cured by light in the ultraviolet wavelength region, the light to be irradiated is irradiated with light including at least light in the ultraviolet wavelength region. As a result, the portion of the photocurable resin 20A that has been irradiated with light is cured, but the photocurable resin 20A has a light shielding property, so that normally, the amount of light necessary for curing is irradiated. It takes time. However, in the present embodiment, the ultraviolet / infrared light reflection film 12 made of a dielectric multilayer film that reflects light in the ultraviolet wavelength region is provided on the back surface (surface on the filter body 10 side) side of the light shielding layer 20. The light that enters the light shielding layer 20 and cures the photocurable resin 20A is reflected by the ultraviolet / infrared light reflection film 12 and returns to the light shielding layer 20, thereby contributing to the curing of the light shielding layer. For this reason, the photocurable resin 20A can be quickly cured.

  After that, the light-shielding layer 20 is formed by selectively removing the uncured portion of the photocurable resin 20A by development (FIG. 2C). For the development, wet development, dry development, or the like is used. In the case of wet development, a developer corresponding to the type of the photocurable resin 20A, such as an alkaline aqueous solution, an aqueous developer, an organic solvent, or the like can be used by a known method such as a dip method, a spray method, brushing, or sapping. . After the development, the light shielding layer 20 may be further cured by heating at about 80 to 250 ° C. or irradiation with light as necessary.

  As described above, in the near-infrared cut filter 100 of the present embodiment, the filter main body 10 includes the ultraviolet / infrared light reflection film 12, so that the light-shielding layer having a diaphragm function and excellent in durability is a photo-curing type. It can be formed easily and in a short time using a resin. Therefore, the productivity and durability of the near-infrared cut filter having both the aperture function and the near-infrared cut function can be improved.

  FIG. 3 shows a case where the light shielding layer 20 is formed without providing the ultraviolet / infrared light reflecting film on one main surface of the transparent substrate 11 in order to confirm the effect of the ultraviolet / infrared light reflecting film 12 ( I) and a light-shielding layer on the surface of the ultraviolet / infrared light reflecting film 12 of the transparent substrate 11 provided with an ultraviolet / infrared light reflecting film 12 and an antireflection film 13 on both main surfaces as shown in FIG. It is the graph which showed the result of having investigated the relationship between the exposure time with respect to 20 A of photocurable resins, and the film thickness of the hardened photocurable resin 20A when (20) is formed. When the exposure amount to the photo-curable resin 20A is insufficient, the amount of the photo-curable resin 20A to be cured decreases, so that the film thickness after curing becomes thin. In FIG. 3, “UV-IR” and “AR” mean an ultraviolet / infrared light reflection film and an antireflection film, respectively.

  As is apparent from the graph, the photocurable resin 20A provided on the ultraviolet / infrared light reflecting film 12 is rapidly cured even in a short time, whereas the light provided directly on the transparent substrate 11 is used. It took time to cure the curable resin 20A, and the effect of the ultraviolet / infrared light reflecting film 12 on the curability of the photocurable resin 20A was confirmed.

  FIG. 4 is a plan view of the near-infrared cut filter 100 of the present embodiment as viewed from the light shielding layer 20 side. As shown in FIG. 4, in this embodiment, the planar shape of the filter body 10 is circular, and the light shielding layer 20 is provided in an annular shape along the outer periphery thereof. As shown in FIG. 2, it may be rectangular and is not particularly limited.

  Hereinafter, the transparent base material 11, the ultraviolet / infrared light reflection film 12 and the antireflection film 13 which constitute the filter body 10 of the near-infrared cut filter 100 of this embodiment will be described in detail.

  The shape of the transparent substrate 11 is not particularly limited as long as it transmits light in the visible wavelength region, and examples thereof include a plate shape, a film shape, a block shape, and a lens shape. The transparent substrate 11 may be a resin containing infrared absorbing glass or an infrared absorbing agent.

  Constituent materials of the transparent substrate 11 include glass, crystal, lithium niobate, sapphire, etc., polyester resin such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene, polypropylene, ethylene vinyl acetate copolymer And polyolefin resins such as norbornene resin, polyacrylate and polymethyl methacrylate, urethane resin, vinyl chloride resin, fluororesin, polycarbonate resin, polyvinyl butyral resin, and polyvinyl alcohol resin. These materials may have an absorption characteristic for at least one of the ultraviolet wavelength region and the infrared wavelength region.

  Glass can be appropriately selected from materials that are transparent in the visible wavelength region. For example, borosilicate glass is preferable because it is easy to process and can suppress generation of scratches and foreign matters on the optical surface, and glass containing no alkali component is preferable because of good adhesion and weather resistance.

  Further, as the glass, a light absorption type glass having absorption in an infrared wavelength region in which CuO or the like is added to fluorophosphate glass or phosphate glass can also be used. In particular, fluorophosphate glass or phosphate glass added with CuO has a high transmittance for light in the visible wavelength region, and CuO sufficiently absorbs light in the near infrared wavelength region. Can provide a near-infrared cut function.

As a specific example of the fluorophosphate glass containing CuO, P ₂ O ₅ 46-70%, MgF ₂ 0-25%, CaF ₂ 0-25%, SrF ₂ 0-25%, LiF 0 to 20%, NaF 0 to 10%, KF 0 to 10%, but the total amount of LiF, NaF and KF is 1 to 30%, AlF ₃ 0.2 to 20%, ZnF _{2 2 to} 15% (however, And 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass of CuO with respect to 100 parts by mass of a fluorophosphate glass comprising up to 50% of the total amount of fluoride. Can be mentioned. As a commercial item, NF-50 glass (Asahi Glass Co., Ltd. brand name) etc. are illustrated.

As a specific example of the phosphate glass containing CuO, P ₂ O ₅ 70 to 85%, Al ₂ O ₃ 8 to 17%, B ₂ O ₃ 1 to 10%, Li ₂ O 0 by mass%. 100% by mass of phosphate glass composed of ˜3%, Na ₂ O 0-5%, K ₂ O 0-5%, Li ₂ O + Na ₂ O + K ₂ O 0.1-5%, SiO ₂ 0-3% In contrast, 0.1 to 5 parts by mass, preferably 0.3 to 2 parts by mass of CuO is included.

  Although the thickness of the transparent base material 11 is not specifically limited, The range of 0.1-3 mm is preferable from the point which aims at size reduction and weight reduction, and the range of 0.1-1 mm is more preferable.

  As described above, the ultraviolet / infrared light reflection film 12 has a function of accelerating the formation of the light shielding layer 20, but at the same time, has an effect of imparting or enhancing a near infrared cut filter function. The ultraviolet / infrared light reflecting film 12 is formed by alternately forming a dielectric layer A and a dielectric layer B having a refractive index higher than that of the dielectric layer A by a sputtering method, a vacuum deposition method, or the like. It is composed of laminated dielectric multilayer films.

As a material constituting the dielectric layer A, a material having a refractive index of 1.6 or less, preferably 1.2 to 1.6 is used. Specifically, silica (SiO ₂ ), alumina, lanthanum fluoride, magnesium fluoride, aluminum hexafluoride sodium, or the like is used. Further, as the material constituting the dielectric layer B, a material having a refractive index of 1.7 or more, preferably 1.7 to 2.5 is used. Specifically, titania (TiO ₂ ), zirconia, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttria, zinc oxide, zinc sulfide and the like are used. The refractive index is a refractive index with respect to light having a wavelength of 550 nm.

  In the present invention, the incidence angle dependency can be reduced by forming the ultraviolet / infrared light reflection film 12 with the following dielectric multilayer film.

That is, this dielectric multilayer film includes 15 unit dielectric layers each composed of a low refractive index dielectric layer A having a refractive index of 1.6 or less and a high refractive index dielectric layer B having a refractive index of 2 or more. When the optical film thickness of the dielectric layer A in the unit dielectric layer is n _L d _L and the optical film thickness of the dielectric layer B is n _H d _H , n _H d _H The number of unit dielectric layers satisfying / n _L d _L ≧ 3 is 10 or more. The unit dielectric layers satisfying n _H d _H / n _L d _L ≧ 3 may have the same or different n _H d _H / n _L d _L values.

From the viewpoint of reducing the incident angle dependency, the total number of unit dielectric layers is preferably 30 or more, and more preferably 35 or more. Further, the number of unit dielectric layers satisfying n _H d _H / n _L d _L ≧ 3 is preferably 15 or more, and more preferably 18 or more.

The average _{n H d H / n L d} L is the average value of _{n H d H / n L d} L in the entire unit dielectric layer is preferably from 4.5 to 6, in particular, all the layers of the unit dielectric layer When the number is large, for example, when the total number of unit dielectric layers is 30 or more, the average n _H d _H / n _L d _L is preferably 4.5 to 5.3.

Furthermore, in the dielectric multilayer film with reduced incidence angle dependency, the average value of the optical film thickness n _L d _L of the dielectric layer A is preferably 40 to 70 nm, and more preferably 40 to 65 nm. The average value of the optical thickness _n H _{d H} of the dielectric layer B is preferably 200~310nm, 210~300nm is more preferable. Further, the optical film thickness n _L d _L of each dielectric layer A is preferably 10 to 140 nm, and the optical film thickness n _H d _H of each dielectric layer B is preferably 10 to 350 nm.
The dielectric multilayer film can be formed by an ion beam method, an ion plating method, a CVD method, or the like in addition to the above-described sputtering method or vacuum deposition method. Since the sputtering method and the ion plating method are so-called plasma atmosphere treatments, adhesion to the near-infrared cut filter glass 11 can be improved.

  The antireflection film 13 has a function of improving the transmittance by preventing reflection of light incident on the near-infrared cut filter 100 and efficiently using incident light, and is formed by a conventionally known material and method. it can. Specifically, the antireflection film 3 is made of silica, titania, tantalum pentoxide, magnesium fluoride, zirconia, alumina or the like formed by sputtering, vacuum deposition, ion beam, ion plating, CVD, or the like. It is composed of one or more layers, a silicate type formed by a sol-gel method, a coating method, or the like, a silicone type, a fluorinated methacrylate type, or the like. The thickness of the antireflection film 13 is usually in the range of 100 to 600 nm.

  In the present invention, the main surface of the transparent substrate 11 opposite to the main surface on which the ultraviolet / infrared light reflecting film 12 is formed, instead of the antireflection film 13 or the antireflection film 13 and A second ultraviolet / infrared light reflecting film made of a dielectric multilayer film that reflects light in the ultraviolet wavelength region and the infrared wavelength region may be provided between the transparent base material 11 and the transparent base material 11.

  The dielectric multilayer film constituting the second ultraviolet / infrared light reflecting film is not particularly limited, and the same material as the dielectric multilayer film constituting the ultraviolet / infrared light reflecting film 12 is used. It can be formed by a similar method. When the ultraviolet / infrared light reflecting film 12 is composed of the above-described dielectric multilayer film with reduced incidence angle dependency, the second ultraviolet / infrared light reflecting film is as follows. It is preferable to comprise.

  That is, this dielectric multilayer film includes three unit dielectric layers each including a low refractive index dielectric layer A having a refractive index of 1.6 or less and a high refractive index dielectric layer B having a refractive index of 2 or more. More than one layer is laminated.

In addition, the dielectric multilayer film has the unit dielectric layer as a whole when the optical film thickness of the dielectric layer A in the unit dielectric layer is n _L d _L and the optical film thickness of the dielectric layer B is n _H d _{H. n} H _d H _{/ n} L _d average _L is the average value _n H _d H _{/ n} L _{d L} is preferably 0.8 to 1.5, the individual unit dielectric layer 3 _n H _d H / _n in _{The L} d _L value is preferably from 0.1 to 10.

Furthermore, the average value of the optical film thickness n _L d _L of the dielectric layer A in this dielectric multilayer film is preferably 100 to 230 nm, and more preferably 120 to 210 nm. The average value of the optical thickness _n H _{d H} of the dielectric layer B is preferably 100~230nm, 120~210nm is more preferable. In addition, the optical film thickness n _L d _L of each dielectric layer A is preferably 5 to 310 nm, and the optical film thickness n _H d _H of each dielectric layer B is preferably 10 to 300 nm.

  Further, the light shielding layer 20 may be formed on the main surface of the filter body 10 on the side of the antireflection film 13 like the near infrared cut filter 110 shown in FIG. Even in this case, since the ultraviolet / infrared light reflection film 12 can function as a functional layer that promotes the formation of the light shielding layer 20, the same effect as the infrared light transmission filter 100 shown in FIG. can get.

  That is, the light irradiated to cure the light shielding layer 20 is reflected by the ultraviolet / infrared light reflection film 12 and reenters the light shielding layer 20, so that the light shielding layer 20 can be cured quickly. However, in this case, since the light irradiated to the light shielding layer 20 reaches the ultraviolet / infrared light reflecting film 12 through the antireflection film 13 and the transparent base material 11, the transparent base material 11 may not be an absorption type material, Or it is necessary to use the material hardened | cured with the light which is not absorbed by the transparent base material 11 for the material of the light shielding layer 20. FIG. From such a viewpoint, in the near-infrared cut filter 110 shown in FIG. 6, it is preferable to use an ultraviolet curable resin that is cured by light in the ultraviolet wavelength region. In the case where the second ultraviolet / infrared light reflecting film is provided on the main surface of the transparent substrate 11 opposite to the main surface on which the ultraviolet / infrared light reflecting film 12 is formed, the second ultraviolet / infrared light reflecting film is provided. The ultraviolet / infrared light reflecting film has a function of promoting the formation of the light shielding layer 20 in the near infrared cut filter 110 shown in FIG. There is no need to do it.

(Second Embodiment)
FIG. 7 is a cross-sectional view schematically showing a near-infrared cut filter 120 according to the second embodiment of the present invention. From this embodiment onward, in order to avoid redundant description, description of points that are common to the first embodiment will be omitted, and differences will be mainly described.

  As shown in FIG. 7, the near-infrared cut filter 120 of the present embodiment is provided with an infrared light absorption film 15 between the transparent substrate 11 and the antireflection film 13. The infrared light absorbing film 15 may be provided between the transparent substrate 11 and the ultraviolet / infrared light reflecting film 12.

  The infrared light absorption film 15 is made of a transparent resin containing an infrared absorber that absorbs light in the infrared wavelength region.

  The transparent resin only needs to transmit light in the visible wavelength region. For example, acrylic resin, styrene resin, ABS resin, AS resin, polycarbonate resin, polyolefin resin, polyvinyl chloride resin, acetate resin, cellulose resin Polyester resin, allyl ester resin, polyimide resin, polyamide resin, polyimide ether resin, polyamideimide resin, epoxy resin, urethane resin, urea resin, and the like.

Infrared absorbers that absorb light in the infrared wavelength region include inorganic fine particles such as ITO (In ₂ O ₃ —TiO ₂ ), ATO (ZnO—TiO ₂ ), lanthanum boride, and cyanine compounds. Organic dyes such as phthalocyanine compounds, naphthalocyanine compounds, dithiol metal complex compounds, diimonium compounds, polymethine compounds, phthalide compounds, naphthoquinone compounds, anthraquinone compounds, and indophenol compounds.

In addition, the inorganic fine particles are composed of oxide crystallites containing at least Cu and / or P, and have a number average agglomerated particle diameter of 5 to 200 nm, preferably a crystal of a compound represented by the following formula (1) Those having a number average aggregate particle diameter of 5 to 200 nm can be used.
A _{1 / n} CuPO ₄ (1)
(In the formula, A is at least one selected from the group consisting of alkali metals (Li, Na, K, Rb, Cs), alkaline earth metals (Mg, Ca, Sr, Ba) and NH ₄ ; N is 1 when A is an alkali metal or NH ₄ and is 2 when A is an alkaline earth metal.)

  Those composed of crystallites can maintain the infrared absorption characteristics due to the crystal structure, and since the crystallites are fine particles, they can be contained in the infrared light absorption film 15 at a high concentration, and per unit length. It is preferable because the absorption capacity can be increased.

  The inorganic fine particles may be subjected to a surface treatment by a known method for the purpose of improving the weather resistance, acid resistance, water resistance and the like and improving the compatibility with the binder resin by surface modification.

  Further, as an organic dye, a dye having a maximum absorption peak having a peak wavelength of 695 ± 1 nm and a full width at half maximum of 35 ± 5 nm in an absorption spectrum of light having a wavelength region of 400 to 1000 nm measured by dissolving in acetone. Can be used. Such a dye is preferable because the absorbance changes sharply in the vicinity of the wavelength of 630 to 700 nm required for the near infrared cut filter. In addition, when using this pigment | dye, use of transparent resin whose refractive index in wavelength 589nm is 1.54 or more is preferable as transparent resin.

  An infrared absorber may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The content of the infrared absorbent in the infrared light absorbing film 15 is preferably 20 to 60% by mass, for example, in the case of the inorganic fine particles composed of oxide crystallites containing at least Cu and / or P as described above. The mass% is more preferable. In the case of a dye having a maximum absorption peak with a peak wavelength of 695 ± 1 nm and a full width at half maximum of 35 ± 5 nm, 0.5 to 3% by mass is preferable, and 0.5 to 0.8% by mass is more preferable. preferable. If the content of each infrared absorber is less than the above range, light in the infrared wavelength region may not be sufficiently absorbed, and if it exceeds the above range, the light transmittance in the visible wavelength region may be reduced. .

  In addition to the infrared absorber, the transparent resin further includes a color tone correction dye, a leveling agent, an antistatic agent, a heat stabilizer, an antioxidant, a dispersant, a flame retardant, and a lubricant as long as the effects of the present invention are not impaired. Further, a plasticizer or the like may be contained.

  The infrared light absorption film 15 is prepared by, for example, preparing a coating liquid by dispersing or dissolving a transparent resin, an infrared absorber, and other additives blended as necessary in a dispersion medium or solvent. It can be formed by applying the working liquid to the main surface of the transparent substrate 11 opposite to the surface on which the ultraviolet / infrared light reflecting film 12 is formed and drying. Coating and drying can be carried out in multiple steps. Moreover, in that case, you may prepare several coating liquid from which a content component differs, and apply and dry these in order. Specifically, for example, a coating liquid containing inorganic fine particles composed of oxide crystallites containing at least Cu and / or P described above and a coating liquid containing ITO particles are individually prepared, and these are sequentially prepared. It may be applied and dried.

  Examples of the dispersion medium or solvent include water, alcohol, ketone, ether, ester, aldehyde, amine, aliphatic hydrocarbon, alicyclic hydrocarbon, and aromatic hydrocarbon. These may be used alone or in combination of two or more. A dispersing agent can be mix | blended with a coating liquid as needed. As the dispersant, for example, a surfactant, a silane compound, a silicone resin, a titanate coupling agent, an aluminum coupling agent, a zircoaluminate coupling agent, or the like is used.

  For the preparation of the coating solution, a stirring device such as a rotation / revolution mixer, a bead mill, a planetary mill, or an ultrasonic homogenizer can be used. In order to ensure high transparency, it is preferable to sufficiently stir. Stirring may be performed continuously or intermittently.

  For coating of coating liquid, spin coating method, bar coating method, dip coating method, casting method, spray coating method, bead coating method, wire bar coating method, blade coating method, roller coating method, curtain coating method A slit die coating method, a gravure coating method, a slit reverse coating method, a micro gravure method, a comma coating method and the like can be used.

  The thickness of the infrared light absorbing film 15 is preferably in the range of 0.01 to 200 μm, and more preferably in the range of 0.1 to 50 μm. If the thickness is less than 0.01 μm, the predetermined absorption ability may not be obtained. If the thickness exceeds 200 μm, drying unevenness may occur during drying.

  Since the near-infrared cut filter 120 of this embodiment includes the infrared light absorption film 15, it can have a good near-infrared cut function.

(Third embodiment)
FIG. 8 is a cross-sectional view schematically showing a near-infrared cut filter 130 according to the third embodiment of the present invention.

  As shown in FIG. 8, the near-infrared cut filter 130 of the present embodiment is made of a black metal or metal oxide such as Cr or CrO on the main surface of the filter body 10 on the ultraviolet / infrared light reflecting film 12 side. A light shielding layer 21 is formed.

The light shielding layer 21 can be formed, for example, as shown in FIG.
First, a photoresist 81 is applied to the entire surface of the ultraviolet / infrared light reflecting film 12 of the filter body 10 (FIG. 9A). The photoresist is not particularly limited as long as it can change the curing or solubility by light in at least the ultraviolet wavelength region or the infrared wavelength region. Photoresist coating methods include spin coating, bar coating, dip coating, casting, spray coating, bead coating, wire bar coating, blade coating, roller coating, curtain coating, and slit die coating. The method, the gravure coating method, the slit reverse coating method, the micro gravure method, the comma coating method, etc. can be used. The application may be performed in a plurality of times. Prior to coating, the surface of the ultraviolet / infrared light reflecting film 12 may be treated with hexamethyldisilazane (HMDS) or the like in order to improve the adhesion to the ultraviolet / infrared light reflecting film 12.

Next, light L is irradiated to the photoresist 81 through the photomask 14 (FIG. 9B). When the photoresist 81 is a positive type, the photomask 14 having an opening corresponding to the light shielding layer 21 is used. When the photoresist 81 is a negative type, a position corresponding to a portion where the light shielding layer 21 is not formed is used. An opened photomask 14 is used. In addition, for example, if the photoresist 81 changes its curing or solubility by light in the ultraviolet wavelength region, at least light including light in such an ultraviolet wavelength region is irradiated. As a result, the portion of the photoresist 81 irradiated with light changes its curing or solubility, but the light in the ultraviolet wavelength region and the infrared wavelength region on the back surface (surface on the filter body 10 side) side of the photoresist 81. ultraviolet and infrared light reflecting film 12 formed of a dielectric multilayer film for reflecting is provided, since the light incident on the photoresist 81 is reflected by the ultraviolet and infrared light reflecting film 12, the photoresist 81 is promptly Change curing or solubility.

  Next, the photoresist 81 is developed using a developer corresponding to the photoresist 81, and a resist layer 82 is formed in the portion where the light shielding layer 21 is not formed on the surface of the ultraviolet / infrared light reflection film 12 (FIG. 9C). )).

  Next, a film 21A made of a black metal such as Cr or CrO or a metal oxide is formed on the resist layer 82 and the ultraviolet / infrared light reflecting film 12 by sputtering, vacuum deposition, or the like (FIG. 9 ( d)).

  Thereafter, the resist layer 82 is lifted off by dipping in a resist remover such as N-methyl-2-pyrrolidone (NMP) or isopropyl alcohol, whereby the light shielding layer 21 is formed (FIG. 9E). For lift-off of the resist layer 82, physical means such as a high-pressure jet or ultrasonic vibration may be used.

  Thus, in the near-infrared cut filter 130 of this embodiment, the filter main body 10 is provided with the ultraviolet / infrared light reflection film 12, and the resist layer 82 can be formed in a short time. The formation time of the layer 21 can be shortened. Further, since the coating 1A to be the light shielding layer 21 can be formed by a sputtering method, a vacuum deposition method, or the like, the light shielding layer 21 having good adhesion to the ultraviolet / infrared light reflecting film 12 can be formed. Therefore, the productivity and durability of the near-infrared cut filter having both the aperture function and the near-infrared cut function can be improved.

(Fourth embodiment)
FIG. 10 is a cross-sectional view schematically showing an imaging apparatus 50 according to the fourth embodiment.

  As shown in FIG. 10, the imaging apparatus 50 according to the present embodiment includes a solid-state imaging device 51, an optical filter 52, a lens 53, and a casing 54 that holds and fixes them.

  The solid-state image sensor 51, the optical filter 52, and the lens 53 are disposed along the optical axis x, and the optical filter 52 is disposed between the solid-state image sensor 51 and the lens 53. The solid-state imaging device 51 is an electronic component that converts light incident through the lens 53 and the optical filter 52 into an electrical signal, and is, for example, a CCD or a CMOS. In this embodiment, the near-infrared cut filter 100 shown in FIG. 1 is used as the optical filter 52, the ultraviolet / infrared light reflection film 12 is on the lens 53 side, and the antireflection film 13 is the solid-state image sensor 51. It is arranged to be located on the side. The near-infrared cut filter 100 may be disposed such that the ultraviolet / infrared light reflection film 12 is positioned on the solid-state imaging device 51 side and the antireflection film 13 is positioned on the lens 53 side. In the present embodiment, the near-infrared cut filter 100 shown in FIG. 1 is used as the optical filter 52, but the near-infrared cut filter shown in FIGS. 6, 7, 8 and the like can also be used. .

  In the imaging device 50, light incident from the subject side enters the solid-state imaging device 51 through the lens 53 and the optical filter 52 (near infrared cut filter 100). The solid-state image sensor 51 converts the incident light into an electric signal and outputs it as an image signal. Incident light passes through the near-infrared cut filter 100 provided with the light-shielding layer 20, is adjusted to an appropriate amount of light, and is received by the solid-state imaging device 51 as light with sufficient near-infrared shielding.

  Thus, in the imaging device 50, since the light shielding layer 20 provided integrally with the near-infrared cut filter 100 has a diaphragm function, it is not necessary to provide a diaphragm separately, and the size can be reduced and the parts can be reduced. The number can be reduced and the manufacturing process can be simplified. In addition, since the near-infrared cut filter 100 can shorten the formation time of the light shielding layer 20 and improve its characteristics, the imaging device 50 can also improve its productivity.

  Note that the imaging device 50 according to the present embodiment has only one lens, but may include a plurality of lenses, and a cover glass or the like that protects the solid-state imaging device is arranged. It may be. Furthermore, the position of the optical filter is not limited to between the lens and the solid-state imaging device, and may be disposed on the subject side of the lens, for example. Also, when a plurality of lenses are disposed, between the lenses. May be arranged.

  The embodiments described above are examples of filters in which the optical filter has a near-infrared cut function, but are not limited to the near-infrared cut function, but include functions such as a low-pass filter, an ND filter, a color filter, and an optical amplification filter. It may have.

  Further, in the embodiment described above, as a functional layer that reflects light used when forming the light shielding layer of the optical filter, light in the visible wavelength region is transmitted, but light in the ultraviolet wavelength region and infrared wavelength region is reflected. Although an ultraviolet / infrared light reflecting film made of a dielectric multilayer film is provided, the functional layer is not particularly limited to this example as long as it can reflect light used for forming the light shielding layer. For example, when the light shielding layer is formed of a photocurable resin, and the light for curing the photocurable resin is light in the ultraviolet wavelength region, the functional layer at least emits light in the ultraviolet wavelength region necessary for curing. It only needs to have a function of reflecting.

  As mentioned above, although several embodiment of this invention was described, this invention is not limited to the content of description of embodiment described above, In the range which does not deviate from the summary of this invention, it can change suitably. Needless to say.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples at all. In addition, the spectral transmittance curve of the near-infrared light transmission filter in an Example was measured using the spectrophotometer (MCPD-3000 by Otsuka Electronics Co., Ltd.).

Example 1
Silica (SiO ₂ ; refractive index 1.45 (wavelength 550 nm)) is formed on one surface of a 40 mm × 40 mm × 0.3 mm square plate-shaped infrared absorbing glass (NF-50 glass manufactured by Asahi Glass Co., Ltd.) by vacuum deposition. Layers and titania (TiO ₂ ; refractive index: 2.32 (wavelength: 550 nm)) layers were alternately laminated to form a dielectric multilayer film (34 layers) having the structure shown in Table 1. A three-layer antireflection film having the structure shown in Table 2 was formed on the other surface of the infrared absorbing glass.

A light-shielding UV-curable acrylate resin (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to the entire surface of the dielectric multilayer film to a thickness of 1.2 μm by spin coating, heated at 90 ° C. for 120 seconds, and then the surface The film was cured by irradiating with 100 mJ / cm ² ultraviolet rays through a photomask with a high-pressure mercury lamp. Then, the unexposed part was removed using 0.04 mass% potassium hydroxide aqueous solution, the light shielding layer was formed, and the near-infrared cut filter was manufactured.

  The formed light-shielding layer was sufficiently cured and had good adhesion to the dielectric multilayer film. The spectral transmittance curve (incident angle 0 degree) of the obtained near-infrared cut filter is shown in FIG.

(Comparative Example 1)
A near-infrared cut filter is manufactured in the same manner as in Example 1, except that the dielectric multilayer film and the antireflection film are not formed, and a light-shielding layer is directly formed on one surface of the infrared absorbing glass (NF-50 glass). As a result, the light-shielding ultraviolet curable acrylate resin could not be sufficiently cured by irradiation with ultraviolet rays of 100 mJ / cm ² .

(Example 2)
A near-infrared cut filter was manufactured in the same manner as in Example 1 except that a soda glass plate having a thickness of 0.3 mm was used instead of the infrared absorbing glass (NF-50 glass).
The formed light-shielding layer was sufficiently cured and had good adhesion to the dielectric multilayer film. The spectral transmittance curve (incident angle 0 degree) of the obtained near-infrared cut filter is also shown in FIG.

(Example 3)
A dielectric multilayer film having a structure as shown in Table 3 is formed on one side of a 40 mm × 40 mm × 0.3 mm square plate-like soda glass with an infrared light absorption layer having a thickness of 8 μm. 68 layer), and an antireflection layer having the structure shown in Table 4 was formed on the surface of the infrared absorption layer. Thereafter, a light shielding layer was formed on the surface of the dielectric multilayer film in the same manner as in Example 1 to produce a near-infrared cut filter. The method for forming the infrared light absorption layer is as follows.

An infrared absorption dye having a pattern whose light absorption spectrum in a wavelength region of 400 to 1000 nm measured by dissolving in acetone is shown in FIG. 11 and a 50% by mass solution of an acrylic resin (manufactured by Osaka Gas Chemical Co., Ltd.) After mixing at a ratio such that the infrared absorbing dye was 0.8 parts by mass with respect to 100 parts by mass of the resin, the mixture was stirred and dissolved at room temperature to obtain a coating solution. The obtained coating liquid was applied on a soda glass plate having a thickness of 1 mm by a die coating method using an applicator having a gap of 30 μm, and dried by heating at 100 ° C. for 5 minutes. Thereafter, the coating film was irradiated with ultraviolet light having a wavelength of 365 nm at 360 mJ / cm ² and cured to form an infrared light absorption layer having a thickness of 8 μm.

  The formed light-shielding layer was sufficiently cured and had good adhesion to the dielectric multilayer film.

Example 4
Other than forming an infrared light absorbing layer having a thickness of 54 μm with a two-layer structure on one side of a 40 mm × 40 mm × 0.3 mm square soda glass instead of an infrared light absorbing layer having a thickness of 8 μm Produced a near-infrared cut filter in the same manner as in Example 3. The method for forming the infrared light absorption layer is as follows.

First, infrared absorbing particles were produced.
To 500 g of an aqueous solution of 52% by mass dipotassium hydrogen phosphate (manufactured by Junsei Kagaku), 500 g of an aqueous solution of 5% by mass copper sulfate pentahydrate (manufactured by Junsei Kagaku) is added and stirred at room temperature for 5 hours or more A solution (PO ₄ ³⁻ / Cu ²⁺ (molar ratio) = 15) was obtained.

  The product was separated from the obtained light blue solution by suction filtration and washed with water and acetone to obtain a light blue product. The product was transferred to a crucible and vacuum-dried at 100 ° C. for 4 hours, and then dry pulverization for 30 seconds was performed twice using a wonder blender (manufactured by Osaka Chemical Co., Ltd., hereinafter the same).

  The powdered product was transferred to a crucible and fired at 600 ° C. for 8 hours in the air to obtain a yellow-green fired product. The fired product was subjected to dry grinding for 30 seconds twice using a wonder blender. The obtained yellowish green fired product was 15.4 g, and the yield based on the number of moles of copper sulfate pentahydrate was 78%.

X-ray diffraction was measured for the fired product. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ could be confirmed, and the fired product was identified as particles substantially consisting of crystallites of KCuPO ₄ .

  The fired product was dispersed in water to obtain a dispersion having a solid content of 10% by mass, treated with an ultrasonic homogenizer, and then wet pulverized using a wet micronizer (Starburst Mini manufactured by Sugino Machine Co., Ltd.). . The number of times the dispersion passes through the orifice diameter is defined as the number of wet pulverization treatments. In this example, the number of wet pulverization treatments was 20.

  The crushed material was centrifuged from the dispersion after wet pulverization, transferred to a crucible, and dried at 150 ° C. to obtain a yellow-green crushed material. About the crushed material, 30 seconds of dry pulverization was performed twice using a wonder blender.

X-ray diffraction of the crushed material was measured. From the result of X-ray diffraction, the crystal structure of KCuPO ₄ could be confirmed, and the crushed material was identified to be near-infrared absorbing particles substantially consisting of KCuPO ₄ crystallites. The crystallite size was 27 nm. In addition, a dispersion for measuring the particle size of near-infrared absorbing particles was prepared, and the number average aggregated particle size was measured and found to be 89 nm. Furthermore, the diffuse reflection spectrum (reflectance) of the near-infrared absorbing particles was measured, and the change D in reflectivity was determined to be -0.46% / nm.

  The obtained near-infrared absorbing particles and a 30% by mass cyclohexanone solution of a polyester resin (trade name Byron 103; manufactured by Toyobo Co., Ltd .; refractive index: 1.60 to 1.61) having a solid content of 44% by weight of the near-infrared absorbing particles. % And a ratio of 56% by mass of the polyester resin, and the mixture was stirred with a rotation / revolution mixer to obtain a dispersion. The obtained dispersion was applied onto a 1 mm thick soda glass plate using a film applicator (No. 548-YKG manufactured by Yasuda Seiki Seisakusho), heated at 150 ° C. for 15 minutes, and absorbed by infrared rays having a thickness of 50 μm. Layer (I) was formed.

Further, ITO particles (manufactured by Fuji Titanium Co., Ltd .; crystallite size 38 nm) were mixed with ethanol together with a dispersant to obtain a dispersion having a solid content concentration of 20% by weight.
This ITO particle-containing dispersion was applied onto the near-infrared absorbing layer (I) using a spin coater (spin coater MS-A200) and heated at 150 ° C. for 15 minutes to form a near-infrared absorbing layer (II) having a thickness of 4 μm. Formed.

  The formed light-shielding layer was sufficiently cured and had good adhesion to the dielectric multilayer film.

(Example 5)
A silica (SiO ₂ ; refractive index 1.45 (wavelength 550 nm)) layer and titania are formed on one surface of a 40 mm × 40 mm × 0.3 mm square plate-shaped infrared absorbing glass (NF-50 glass) by vacuum deposition. (TiO ₂ ; refractive index: 2.32 (wavelength: 550 nm)) layers were alternately laminated to form a dielectric multilayer film (34 layers) having a structure as shown in Table 1. A three-layer antireflection film having the structure shown in Table 2 was formed on the other surface of the infrared absorbing glass.

A positive photoresist (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to the entire surface of the dielectric multilayer film to a thickness of 4.0 μm by spin coating, heated at 90 ° C. for 90 seconds, and then a photomask is applied to the surface. Then, ultraviolet rays of 100 mJ / cm ² were irradiated by a high pressure mercury lamp. Thereafter, the exposed portion was dissolved and removed with tetramethylammonium hydroxide, and post-cured at 120 ° C. for 3 minutes to form a resist layer.

A 0.3 μm thick film made of Cr, CrO _x , SiO ₂ is formed on the resist layer and the dielectric multilayer film by magnetron sputtering, and then immersed in N-methyl-2-pyrrolidone to form a resist layer Was lifted off to form a light shielding layer to produce a near-infrared cut filter.

  The optical filter of the present invention can shorten the formation time of the light-shielding layer functioning as a diaphragm, improve its durability, and thus improve the productivity and reliability of the imaging device, so that a digital still camera, a digital video camera, It is useful for an imaging apparatus such as a small camera incorporated in information equipment such as a mobile phone, a notebook personal computer, and a PDA.

  DESCRIPTION OF SYMBOLS 10 ... (Near-infrared cut) Filter body, 11 ... Transparent base material, 12 ... Ultraviolet / infrared light reflection film, 13 ... Antireflection film, 15 ... Infrared light absorption film, 20, 21 ... Light shielding layer, 20A ... Light Curable resin, 50 ... imaging device, 51 ... solid-state imaging device, 52 ... optical filter, 53 ... lens, 54 ... housing, 100, 110, 120, 130 ... near-infrared cut filter.

Claims (8)

An optical filter used in an image pickup apparatus including an image pickup element on which light from a subject or a light source is incident,
A filter body disposed between the subject or the light source and the image sensor and having transparency to the incident light;
A light shielding layer that is formed integrally with at least one surface of the optical filter body with a photocurable resin and blocks a part of light incident on the imaging element;
The optical filter body is provided with a functional layer that reflects light that cures the photocurable resin ,
A surface of the functional layer is flat, the light shielding layer is provided in contact with the surface, and the functional layer is a light reflecting film made of a dielectric multilayer film .   The optical filter according to claim 1, which is an optical filter having a near infrared cut function. The functional layer is 請 Motomeko 1 or 2 optical filter according you reflect light in the ultraviolet wavelength region. The said light shielding layer is provided in the outer peripheral part of the said functional layer surface, and the said functional layer permeate | transmits the light of a visible wavelength region, and reflects the light of an ultraviolet wavelength region and an infrared wavelength region. The optical filter according to claim 1.   The optical filter according to any one of claims 1 to 4, wherein the optical filter main body includes an infrared absorbing glass that absorbs light in an infrared wavelength region.   6. The optical filter according to claim 1, wherein the optical filter main body includes an infrared light absorbing film including an infrared absorbent that absorbs light in an infrared wavelength region. An optical filter used in an image pickup apparatus including an image pickup element on which light from a subject or a light source is incident,
A filter body disposed between the subject or the light source and the image sensor and having transparency to the incident light;
A light-blocking layer that is integrally patterned by photolithography on at least one surface of the optical filter body, and that blocks a part of light incident on the imaging element;
The optical filter body is provided with a functional layer that reflects light used for the photolithography ,
A surface of the functional layer is flat, the light shielding layer is provided in contact with the surface, and the functional layer is a light reflecting film made of a dielectric multilayer film . An image sensor that receives light from a subject or a light source;
A lens disposed between the subject or light source and the image sensor;
Wherein the object or a light source which is disposed between the imaging element, an imaging apparatus characterized by comprising an optical filter of any one of claims 1 to 7.

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