Optical filters

Abstract

To provide an optical filter capable of obtaining a high transmittance in a necessary wavelength range (for example, a visible range) even while effectively intercepting light in an unnecessary wavelength range (for example, light in an ultraviolet and infrared range), and applications thereof.SOLUTION: An optical filter includes a substrate and a transmittance control layer formed on one or both surfaces of the substrate. The absolute value of a difference between the refractive index of the transmittance control layer and that of the substrate is 2-10%; and ▵T1 of the following formula 1 is 0.5% or more. The formula 1 is ▵T1=100×(TF1-TS1) / TS1, where in the formula 1, TF1 is the average transmittance of the optical filter in a wavelength range of 481-560 nm, and TS1 is the average transmittance of the optical filter without including the transmittance control layer in a wavelength range of 481-560 nm.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present application relates to an optical filter and an imaging device. Background Art

[0002] Optical filters are used in imaging devices employing CCD (Charge-Coupled Device), CMOS (complementary metal oxide semiconductor) image sensors, and the like. Such an optical filter, also referred to as a near-infrared cut filter, is used to obtain favorable color reproducibility and clear images.

[0003] Various characteristics are required for such optical filters.

[0004] The optical filter described above must effectively block light in the ultraviolet and infrared regions, while transmitting visible light at a high transmittance. For this purpose, a rapid and sharp change in transmittance is required at the boundary between the ultraviolet and visible light to be blocked and at the boundary between the infrared and visible light.

[0005] The optical filter is required to maintain the above-described transmission and blocking characteristics even when the incident angle changes. With the development of wide-angle cameras and the like, such characteristics have become more important, and the need for optical filters that maintain transmission and blocking characteristics even at wider incident angles has been increasing.

[0006] In order to manufacture an optical filter having the functions as described above, the optical filter is usually manufactured to have a multilayer structure. That is, in order for the optical filter to transmit light of a desired wavelength and block unnecessary light, the optical filter typically includes a dielectric multilayer film and / or a light absorbing layer.

[0007] As described above, dielectric multilayer films are typically formed by repeatedly stacking high-refractive-index dielectric materials and low-refractive-index dielectric materials. Such films can be designed to block unwanted wavelengths of light through reflection.

[0008] A light-absorbing layer is a film designed to block unwanted wavelengths of light by absorbing them using a variety of dyes.

[0009] By appropriately forming a dielectric multilayer film and / or a light-absorbing layer as described above on an optical filter, light at a desired wavelength can be blocked.

[0010] However, when optical filters are formed in a multilayer structure, unwanted reflections and / or absorptions occur at the interfaces between layers, and such reflections and absorptions cause the optical filter to exhibit low transmittance in wavelength regions where it should exhibit high transmittance (e.g., the visible light wavelength region).

[0011] Recently, optical filters using so-called infrared-absorbing glass (also called blue glass), which has near-infrared absorption properties, as a substrate have also become known. Infrared-absorbing glass is a glass filter in which CuO or the like is added to the glass to selectively absorb light in the near-infrared wavelength range.

[0012] While using such infrared-absorbing glass has the advantage of more effectively blocking light in unwanted wavelength ranges, it also has the disadvantage that the substrate itself exhibits absorption properties, further exacerbating the problem of reduced transmittance caused by reflection and / or absorption phenomena occurring between the layers. [Overview of the project] [Problems that the invention aims to solve]

[0013] This application aims to provide an optical filter and its applications. This application aims to provide an optical filter and its applications that can effectively block unwanted wavelengths of light (e.g., ultraviolet and infrared light) while ensuring high transmittance in the required wavelength range (e.g., the visible light range). [Means for solving the problem]

[0014] Of the physical properties mentioned herein, those whose results are affected by the measurement temperature are those measured at room temperature unless otherwise specified.

[0015] In this specification, room temperature means the natural temperature without heating or cooling, for example, any single temperature within the range of 10°C to 30°C, or a temperature of approximately 23°C or 25°C. Furthermore, unless otherwise specified, the unit of temperature in this specification is Celsius (°C).

[0016] Of the physical properties mentioned herein, those whose results are affected by the measurement pressure are those measured at normal pressure unless otherwise specified.

[0017] In this specification, atmospheric pressure refers to the natural pressure without pressurization or depressurization, and typically means approximately 740 mmHg to 780 mmHg, which is the level of atmospheric pressure.

[0018] In this specification, if the measured humidity affects the results for a physical property, that property is the one measured at the normal temperature and / or atmospheric pressure conditions with unadjusted, natural humidity.

[0019] In this application, if an optical property (e.g., refractive index) is a property that varies with wavelength, unless otherwise specified, such optical property is a property for light with a wavelength of 520 nm.

[0020] In this application, unless otherwise specified, the terms transmittance or reflectance refer to the actual transmittance (measured transmittance) or actual reflectance (measured reflectance) observed at a specific wavelength.

[0021] In this specification, unless otherwise specified, the terms transmittance and reflectance refer to transmittance or reflectance with respect to an incident angle of 0 degrees.

[0022] In this application, unless otherwise specified, the term "average transmittance" refers to the result of calculating the arithmetic mean of the transmittances measured at each wavelength, starting from the shortest wavelength within a given wavelength range and increasing the wavelength by 1 nm increments. For example, the average transmittance in the wavelength range of 350 nm to 360 nm is the arithmetic mean of the transmittances measured at wavelengths of 350 nm, 351 nm, 352 nm, 353 nm, 354 nm, 355 nm, 356 nm, 357 nm, 358 nm, 359 nm, and 360 nm.

[0023] In this specification, the term "maximum transmittance" refers to the highest transmittance measured at each wavelength while increasing the wavelength by 1 nm from the shortest wavelength within a given wavelength range. For example, the maximum transmittance in the wavelength range of 350 nm to 360 nm is the highest transmittance among the transmittances measured at wavelengths of 350 nm, 351 nm, 352 nm, 353 nm, 354 nm, 355 nm, 356 nm, 357 nm, 358 nm, 359 nm, and 360 nm.

[0024] In this specification, the term minimum transmittance refers to the lowest transmittance measured at each wavelength while increasing the wavelength by 1 nm from the shortest wavelength within a given wavelength range. For example, the minimum transmittance within the wavelength range of 350 nm to 360 nm is the lowest transmittance among the transmittances measured at wavelengths of 350 nm, 351 nm, 352 nm, 353 nm, 354 nm, 355 nm, 356 nm, 357 nm, 358 nm, 359 nm, and 360 nm.

[0025] In this specification, the angle of incidence is the angle relative to the normal of the surface being evaluated. For example, the transmittance or reflectance of an optical filter at an angle of incidence of 0 degrees means the transmittance for light incident in a direction substantially parallel to the normal of the optical filter surface. Also, for example, an angle of incidence of 40 degrees is the value for incident light that forms a substantially 40-degree angle with the normal in a clockwise or counterclockwise direction. This definition of the angle of incidence applies equally to other properties such as transmittance or reflectance.

[0026] The optical filter of this application can efficiently and accurately block ultraviolet light near the short-wavelength visible light region and infrared light near the long-wavelength visible light region, thereby realizing a visible light transmission band with high transmittance.

[0027] The optical filter of this application may include a substrate. The substrate may be a transparent substrate. In this specification, a substrate or layer is considered transparent if it exhibits a transmittance of a certain level or higher at a wavelength of about 550 nm. For example, the lower limit of the transmittance of the transparent substrate or transparent layer at a wavelength of 550 nm may be about 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%, and the upper limit may be about 100%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, or 60%. The transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0028] The transparent substrate mentioned above is not particularly limited, and a general substrate used for optical filters can be used. Typically, the substrate used exhibits appropriate transmittance and has appropriate rigidity to maintain the shape of the optical filter. For example, an inorganic material such as glass or crystal, or an organic material such as resin can be used.

[0029] Examples of resin materials that can be used for transparent substrates include, but are not limited to, polyesters such as PET (poly(ethylene terephthalate)) or PBT (poly(butylene terephthalate)), polyolefins such as polyethylene, polypropylene or EVA (ethylene-vinyl acetate copolymer), norbornene polymers, acrylic polymers such as PMMA (poly(methyl methacrylate)), urethane polymers, vinyl chloride polymers, fluoropolymers, polycarbonates, polyvinyl butyral, polyvinyl alcohol, or polyimides.

[0030] Examples of glass materials that can be used for transparent substrates include soda-lime glass, borosilicate glass, alkali-free glass, or quartz glass.

[0031] Examples of crystalline materials that can be used for transparent substrates include birefringent crystals such as quartz, lithium niobate, or sapphire.

[0032] If necessary, a so-called infrared absorbing substrate can be used as the transparent substrate. An infrared absorbing substrate is a substrate that exhibits absorption characteristics in at least a portion of the infrared region. So-called blue glass, which contains copper and exhibits the above characteristics, is a typical example of an infrared absorbing substrate. Such infrared absorbing substrates are useful when constructing optical filters that block light in the infrared region, but are disadvantageous from the viewpoint of ensuring high transmittance in the visible light region due to the above absorption characteristics. In this application, by selecting an infrared absorbing substrate, it is possible to provide an optical filter that efficiently blocks light in the desired ultraviolet and infrared regions while exhibiting high transmittance characteristics in the visible light region.

[0033] As the infrared absorbing substrate, a substrate known as infrared absorbing glass can be used. Such glass is an absorbing glass manufactured by adding CuO or the like to phosphate fluoride glass or phosphate glass. Therefore, in this application, as an example, a CuO-containing phosphate fluoride glass substrate or a CuO-containing phosphate glass substrate may be used as the infrared absorbing substrate. The phosphate glass mentioned above also includes silicophosphate glass, in which part of the glass skeleton is composed of SiO2. Such absorbing glasses are publicly known, and for example, the glass disclosed in Korean Patent No. 10-2056613, or other commercially available absorbing glasses (for example, commercially available products from Hoya, Schott, PTOT, etc.) can be used.

[0034] The transparent substrate (e.g., a glass substrate) may contain copper. For example, the upper limit of the copper content in the transparent substrate may be around 10% by weight, 9% by weight, 8% by weight, or 7% by weight, and the lower limit may be around 0% by weight, 1% by weight, 2% by weight, 3% by weight, 4% by weight, 5% by weight, 6% by weight, or 7% by weight. The copper content may be at or above any one of the lower limits mentioned above, or below any one of the upper limits mentioned above, or at or above any one of the lower limits mentioned above and below any one of the upper limits mentioned above. If the transparent substrate (e.g., a glass substrate) is not a general substrate, i.e., an infrared absorbing substrate, it does not contain copper, so the lower limit of the copper content may be 0% by weight.

[0035] The above substrate may have a refractive index within a predetermined range. For example, the lower limit of the refractive index of the above substrate may be around 1.48, 1.5, or 1.52, and the upper limit may be around 1.6, 1.58, 1.56, 1.54, or 1.52. The above refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0036] The thickness of the transparent substrate described above can usually be adjusted within a range of approximately 0.03 mm to 5 mm, but it is not limited to this range.

[0037] The optical filter of this application may include a transmittance control layer together with the substrate.

[0038] In this specification, the term "transmittance control layer" refers to a layer whose presence or absence affects the transmittance of an optical filter. Specifically, the transmittance control layer may refer to a layer that has a predetermined refractive index relationship with the substrate (described later) and exhibits a higher visible light transmittance in an optical filter having the transmittance control layer compared to an optical filter without the transmittance control layer. In this case, the visible light transmittance is the average transmittance in the wavelength range of approximately 481 nm to 560 nm.

[0039] In one example, the transmittance control layer may mean a layer in which the absolute value of the difference between the refractive index of the transmittance control layer and the refractive index of the substrate is within a certain range. In this specification, the difference between the refractive index of B and the refractive index of A is given by 100 × (n B -n A ) / n A This is the difference calculated by the above, n A This is the refractive index of A, and n B This is the refractive index of B.

[0040] The lower limit of the absolute value of the difference in the refractive index of the transmittance control layer relative to the refractive index of the substrate may be about 2%, 3%, or 4%, and the upper limit thereof may be about 10%, 9%, 8%, 7%, 6%, or 5%. The absolute value may be greater than or equal to, or exceed, any one arbitrary lower limit among the above-mentioned lower limits, may be less than or equal to, or fall below, any one arbitrary upper limit among the above-mentioned upper limits, or may be within a range that is greater than or equal to, or exceeds, any one arbitrary lower limit among the above-mentioned lower limits, and is less than or equal to, or falls below, any one arbitrary upper limit among the above-mentioned upper limits.

[0041] The transmittance control layer may have a higher refractive index than the substrate or a lower refractive index than the substrate, as long as it exhibits the above-described refractive index relationship with the substrate.

[0042] Although the reason why the transmittance of the optical filter is increased by including the transmittance control layer is not clear, it is presumed that a suitable repeated laminated structure of high refractive index regions and low refractive index regions is formed in the optical filter depending on the position of the transmittance control layer in the optical filter, and phenomena such as destructive interference caused by such a structure alleviate, cancel out, prevent, or suppress the reflection and absorption of light of a specific wavelength that occurs between layers.

[0043] By the presence of the transmittance control layer in the optical filter, the optical filter can exhibit a higher transmittance within a predetermined wavelength region than that of the transparent substrate.

[0044] For example, in the optical filter, ΔT1 in the following Formula 1 can fall within a predetermined range.

[0045] [Formula 1] ΔT1=100×(T F1 -T S1 ) / T S1

[0046] In Formula 1, T F1 is the average transmittance in the wavelength range of 481 nm to 560 nm of the optical filter including the transmittance control layer, and T S1This is the average transmittance of the optical filter without the transmittance control layer in the wavelength range of 481 nm to 560 nm.

[0047] Above transmittance T S1 The optical filter, except that it does not include the above transmittance control layer, has the above transmittance T F1 It is the same optical filter as the optical filter shown.

[0048] The lower limit of △T1 in Equation 1 above may be approximately 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, and its upper limit may be approximately 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, or 1%. The above △T1 may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0049] In the above formula 1, T F1 The lower limit may be around 80%, 82%, 84%, 86%, 88%, or 89%, and the upper limit may be around 100%, 95%, or 90%. F1 It may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above, and less than or equal to any one of the upper limits mentioned above.

[0050] For example, the above optical filter can have ΔT2 in equation 2 below fall within a predetermined range.

[0051] [Formula 2] △T2 = 100 × (T F2 -T S2 ) / T S2

[0052] In formula 2, T F2 This is the average transmittance of the optical filter including the transmittance control layer in the wavelength range of 466 nm to 480 nm, and T S2 This is the average transmittance of the optical filter without the transmittance control layer in the wavelength range of 466 nm to 480 nm.

[0053] Above transmittance T S2 The optical filter, except that it does not include the above transmittance control layer, has the above transmittance T F2 It is the same optical filter as the optical filter shown.

[0054] The lower limit of △T2 in Equation 2 above may be approximately 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 3.5%, and its upper limit may be approximately 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, or 1%. The above △T2 may be greater than or exceeding any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or exceeding any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0055] In the above formula 2, T F2 The lower limit may be around 80%, 82%, 84%, 86%, 88%, or 89%, and the upper limit may be around 100%, 95%, or 90%. F2 It may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above, and less than or equal to any one of the upper limits mentioned above.

[0056] For example, the above optical filter can have ΔT3 in equation 3 below fall within a predetermined range.

[0057] [Formula 3] △T3 = 100 × (T F3 -T S3 ) / T S3

[0058] In formula 3, T F3 This is the average transmittance of the optical filter including the transmittance control layer in the wavelength range of 425 nm to 465 nm, and T S3 This is the average transmittance of the optical filter without the transmittance control layer in the wavelength range of 425 nm to 465 nm.

[0059] Above transmittance T S3 The optical filter, except that it does not include the above transmittance control layer, has the above transmittance T F3 It is the same optical filter as the optical filter shown.

[0060] The lower limit of △T3 in Equation 3 above may be approximately 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 3.3%, and its upper limit may be approximately 10%, 9.5%, 9%, 8.5%, 8%, 7.5%, 7%, 6.5%, 6%, 5.5%, 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, or 1%. The above △T3 may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0061] In the above formula 3, T F3 The lower limit may be around 65%, 70%, 75%, 80%, 85%, or 90%, and the upper limit may be around 100%, 95%, 90%, 85%, 80%, or 75%. F3It may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above, and less than or equal to any one of the upper limits mentioned above.

[0062] The transmittance control layer described above is a different type of layer from the dielectric multilayer film and light absorption layer typically included in optical filters. Therefore, unlike the dielectric multilayer film, the transmittance control layer may be a single layer. Furthermore, unlike the light absorption layer, the transmittance control layer substantially does not contain absorbents (such as dyes) like so-called ultraviolet absorbers and infrared absorbers. For example, the amount of absorbent in the transmittance control layer may be 1% by weight or less, 0.5% by weight or less, 0.1% by weight or less, 0.05% by weight or less, 0.01% by weight or less, 0.005% by weight or less, or 0.001% by weight or less, and the lower limit may be around 0% by weight.

[0063] The type of material used to form the above-mentioned transmittance control layer is not particularly limited, as long as it can form the transparent layer described above and exhibits the refractive index relationship with the substrate as described above.

[0064] In one example, the transmittance control layer may contain, as the material, one or more selected from the group consisting of polysilazane, silica (SiOx), silane compounds, cyclic olefin polymer (COP), polysilsesquioxane, polyarylate, polyisocyanate, polyimide, polyetherimide, polyamideimide, polyacrylate, polyester, polycarbonate, polyethylene phthalate, epoxy resin, polysulfone, urethane resin, silicone resin, polysiloxane, polysilane, polycarbosilane, fluororesin, and silane compounds. For example, the transmittance control layer may contain organic or inorganic polysilazane as the polysilazane. As is well known, inorganic and organic polysilazanes can be distinguished by the presence or absence of carbon in the functional groups substituted with silicon or nitrogen atoms of the polysilazane.

[0065] The above-mentioned transmittance control layer may also contain other necessary additives to the above-mentioned material, such as curing agents and surfactants.

[0066] The transmittance control layer described above may have a thickness within an appropriate range. For example, the lower limit of the thickness of the transmittance control layer may be approximately 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 50 nm, 100 nm, 110 nm, or 120 nm, and the upper limit may be approximately 1000 nm, 500 nm, 250 nm, 200 nm, 150 nm, 100 nm, 80 nm, 60 nm, 40 nm, or 25 nm. The thickness described above may be greater than or greater than any one of the lower limits described above, or less than or equal to any one of the upper limits described above, or greater than or greater than any one of the lower limits described above and less than or equal to any one of the upper limits described above.

[0067] The transmittance control layer described above may be formed on one or both sides of the substrate. Furthermore, the transmittance control layer may be formed in contact with the substrate, and other layers may exist between the substrate and the transmittance control layer.

[0068] The optical filter of this application comprises the above-mentioned substrate and a transmittance control layer, and may further include known layers. For example, the optical filter may further include an absorption layer formed on one or both sides of the substrate and / or transmittance control layer. The absorption layer is a light-absorbing layer, for example, a layer that absorbs light within at least a portion of the wavelength range of the infrared and / or ultraviolet region. One or more such absorption layers may be formed on the optical filter.

[0069] The above-mentioned absorption layer may be an infrared absorption layer and / or an ultraviolet absorption layer. The above-mentioned absorption layer may also be a layer having both infrared and ultraviolet absorption properties. Such a layer is usually a layer containing an absorbent (dye, pigment, dye, etc.) and a transparent resin, and can be applied to cut out light in the near-ultraviolet and / or near-infrared regions to realize a sharper transmittance band. Such an absorption layer may also be the transparent layer described above.

[0070] In one example, the ultraviolet absorbing layer can be designed to exhibit an absorption maximum in the wavelength range of approximately 300 nm to 390 nm, and the infrared absorbing layer can be designed to exhibit an absorption maximum in the wavelength range of 600 nm to 800 nm.

[0071] In one example, if the light-absorbing layer is a layer that simultaneously exhibits absorption for ultraviolet and infrared light, the light-absorbing layer can be designed to simultaneously exhibit absorption bands in the wavelength region of approximately 300 nm to 390 nm and in the wavelength region of 600 nm to 800 nm.

[0072] The infrared absorption layer and the ultraviolet absorption layer may be composed of a single layer, or they may be composed of separate layers. For example, one layer may be designed to exhibit both the absorption maxima of the ultraviolet absorption layer and the absorption maxima of the infrared absorption layer, or two layers may be formed that exhibit the respective absorption maximas. In addition, there may be multiple infrared absorption layers and / or ultraviolet absorption layers.

[0073] Each absorption layer may contain only one type of absorbent, or, if necessary, two or more types of absorbents for proper blocking of infrared and / or ultraviolet rays.

[0074] For example, the infrared absorbing layer may contain at least a first absorbent having an absorption maximum wavelength in the range of 700 nm to 720 nm and a full width at half maximum in the range of 50 nm to 60 nm, and a second absorbent having an absorption maximum wavelength in the range of 730 nm to 750 nm and a full width at half maximum in the range of 60 nm to 70 nm, and the ultraviolet absorbing layer may contain at least an absorbent having an absorption maximum wavelength in the range of 340 nm to 390 nm.

[0075] The infrared and ultraviolet absorbing layers described above can also consist of a single layer.

[0076] The materials and construction methods for the absorption layer are not particularly limited, and known materials and construction methods can be applied.

[0077] The absorption layer is formed using a material that combines an absorbent (such as a dye or pigment) capable of exhibiting the desired absorption maximum with a transparent resin.

[0078] For example, known absorbers that exhibit an absorption maximum in the wavelength range of approximately 300nm to 390nm can be used as UV absorbers. Examples include Exiton's ABS407; QCR Solutions Corp's UV381A, UV381B, UV382A, UV386A, VIS404A; and HWSands' ADA1225, ADA3209, ADA3216, ADA3217, ADA3218, ADA3230, ADA5205, ADA3217, ADA2055, ADA6798, ADA3102, ADA3204, ADA3210, ADA2041, ADA3201, ADA3202, ADA3215, ADA3219, ADA3225, A Examples include, but are not limited to, DA3232, ADA4160, ADA5278, ADA5762, ADA6826, ADA7226, ADA4634, ADA3213, ADA3227, ADA5922, ADA5950, ADA6752, ADA7130, ADA8212, ADA2984, ADA2999, ADA3220, ADA3228, ADA3235, ADA3240, ADA3211, ADA3221, ADA5220, ADA7158; and CRYSTALYN's DLS 381B, DLS 381C, DLS 382A, DLS 386A, DLS 404A, DLS 405A, DLS 405C, DLS 403A.

[0079] Furthermore, as an infrared absorber, a suitable dye or pigment that exhibits an absorption maximum in the wavelength range of 600 nm to 800 nm can be used. For example, squarylium-based dyes, cyanine-based compounds, phthalocyanine-based compounds, naphthalocyanine-based compounds, or dithiol-based metal complex compounds can be used, but are not limited to these.

[0080] Furthermore, the transparent resin applied to the absorbent layer can be any known resin, for example, one or more of the following can be used: cyclic olefin resins, polyarylate resins, polysulfone resins, polyethersulfone resins, poly-paraphenylene resins, polyarylen etherphosphine oxide resins, polyimide resins, polyetherimide resins, polyamideimide resins, acrylic resins, polycarbonate resins, polyethylene naphthalate resins, and various organic-inorganic hybrid resins.

[0081] Furthermore, such an absorption layer may be formed to have a predetermined refractive index relationship with the substrate. For example, the lower limit of the absolute value of the difference between the refractive index of the light absorption layer and the refractive index of the substrate may be around 0.2%, 0.4%, 0.6%, 0.8%, 1%, 2%, 3%, 4%, 5%, or 6%, and the upper limit may be around 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0.7%. The absolute value may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0082] The above-mentioned light-absorbing layer may have a higher refractive index or a lower refractive index than the substrate, as long as it exhibits the relationship of refractive index with the substrate as described above.

[0083] Such light-absorbing layers are typically formed to have a thickness in the range of approximately 1 μm to 20 μm, but the thickness of the light-absorbing layer is not limited to this range.

[0084] The above-mentioned light-absorbing layer may consist of one or more layers in the optical filter, and if the light-absorbing layer consists of two or more layers, the absorption characteristics of each layer may be the same or different from each other.

[0085] The optical filter of this application may include a so-called dielectric multilayer film as a further layer. Such a multilayer film may be formed on one or both sides of the substrate, the transmittance control layer and / or the light absorption layer.

[0086] Such dielectric multilayer films may typically have a multilayer structure comprising at least two sublayers, each with a different refractive index, and may also include a multilayer structure in which the two sublayers are repeatedly stacked. For example, the dielectric multilayer film may include a structure in which first and second sublayers with different refractive indices are repeatedly stacked.

[0087] The first and second sublayers described above are sublayers separated by the difference in refractive index between them.

[0088] Dielectric multilayer films are films constructed by repeatedly stacking a low refractive index dielectric material and a high refractive index dielectric material, and are used to form so-called IR reflective layers and AR (Anti-reflection) layers. In this application, such known dielectric multilayer films for forming IR reflective layers and AR layers can also be applied.

[0089] The type of material used to form the dielectric multilayer film, i.e., the material used to form each of the above sublayers, is not particularly limited, and known materials can be used. Typically, SiO2 or Na5A is used to manufacture the low refractive index sublayer. l3 F 14 For the production of the high refractive index sublayer, fluorides such as Na3AlF6 or MgF2 can be applied, and materials such as TiO2, Ta2O5, Nb2O5, ZnS, or ZnSe can be used, but the materials applied in this application are not limited to those listed above.

[0090] There are no special restrictions on the selection of the low-refractive index and high-refractive index sublayer materials for forming the dielectric multilayer film, as well as their arrangement and thickness. For example, known design configurations used for forming IR reflective layers and AR (anti-reflection) layers or other dielectric multilayer films can be applied without limitation.

[0091] The method for forming the above-mentioned dielectric multilayer film is not particularly limited, and for example, it can be formed by applying a known deposition method. In the industry, methods for controlling the reflection and transmission characteristics of the dielectric multilayer film by considering the deposition thickness and number of sublayers are known, and in this application, a dielectric multilayer film exhibiting the desired characteristics can be formed by such a known method.

[0092] The optical filter may also be a further layer, which may include an adhesive layer, a bonding layer, and / or a primer layer. Such layers are typically applied in the optical filter to improve the adhesion between layers. In this application, the adhesive layer, bonding layer, and / or primer layer can be formed using known materials.

[0093] In addition to the layers described above, the optical filter may also include a variety of known layers depending on the purpose.

[0094] Depending on the type and configuration of the layers included in the optical filter, the position of the transmittance control layer and the refractive index between each layer of the optical filter can be controlled within the range of the refractive index relationships described above.

[0095] For example, if the above-mentioned adhesive layer, bonding layer, or primer layer is included, the adhesive layer, bonding layer, or primer layer may be included between the light-absorbing layer and the substrate. In such a case, there are no special restrictions on the position of the transmittance control layer, but it may be located on the surface of the substrate opposite to the surface on which the adhesive layer, etc., is formed, or on the surface of the light-absorbing layer opposite to the surface on which the adhesive layer, etc., is formed.

[0096] Figure 1 is a schematic cross-sectional view when the absorption layer 300, adhesive layer etc. 400, substrate 100, and transmittance control layer 200 are sequentially laminated, and Figure 2 is a schematic cross-sectional view when the transmittance control layer 200, absorption layer 300, adhesive layer etc. 400, and substrate 100 are sequentially laminated.

[0097] In the stacked configuration shown in Figures 1 and 2 above, the refractive index n of the substrate 100 The refractive index n of the above light-absorbing layer relative to n 300The difference is 100 × (n 300 -n 100 ) / n 100 The lower limit may be around 0.2%, 0.4%, or 0.6%, and the upper limit may be around 2%, 1.5%, 1%, 0.9%, 0.8%, or 0.7%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0098] In the stacked configuration shown in Figures 1 and 2 above, the refractive index n of the substrate 100 The refractive index n of the adhesive layer, etc., relative to the above adhesive layer. 400 The difference is 100 × (n 400 -n 100 ) / n 100 The lower limit may be around 3%, 4%, or 5%, and the upper limit may be around 10%, 8%, or 6%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0099] In the stacked configurations shown in Figures 1 and 2 above, the refractive index n of the transmittance control layer is 200 The refractive index n of the adhesive layer, etc., relative to the above adhesive layer. 400 The difference is 100 × (n 400 -n 200 ) / n 200The lower limit may be around 8%, 9%, or 10%, and the upper limit may be around 15%, 13%, or 11%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0100] Furthermore, in the stacked configuration shown in Figures 1 and 2 above, the refractive index n of the substrate 100 The refractive index n of the above transmittance control layer relative to the refractive index n 200 The difference is 100 × (n 200 -n 100 ) / n 100 The lower limit may be around -10%, -8%, -6%, or -5%, and the upper limit may be around -2% or -4%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0101] When the stacked configuration shown in Figures 1 and 2 has the refractive index relationship described above, an optical filter can be obtained that ensures the desired transmittance.

[0102] Although not particularly limited, in the structure described above, the light-absorbing layer and the adhesive layer, etc. are in direct contact with each other, the adhesive layer, etc. and the substrate are in direct contact with each other, and the transmittance control layer may be in direct contact with the light-absorbing layer or the substrate.

[0103] The optical filter described above may, in some cases, include two or more light-absorbing layers. For example, the optical filter may include first and second light-absorbing layers having different refractive indices.

[0104] In such cases, a light-absorbing layer having an even lower refractive index may be located closer to the substrate than the other light-absorbing layers. For example, if the first light-absorbing layer has a lower refractive index than the second light-absorbing layer, the first light-absorbing layer may be located between the second light-absorbing layer and the transparent substrate.

[0105] In such a case, the transmittance control layer may be positioned such that the second light absorption layer is located between the transmittance control layer and the first light absorption layer. Figure 3 shows such a structure, illustrating the case where the transmittance control layer 200, the second light absorption layer 302, the first light absorption layer 301, and the substrate 100 are formed sequentially.

[0106] In the case of a structure like that shown in Figure 3, the refractive index n of the substrate 100 is 100 The refractive index n of the first light absorption layer 301 relative to 301 The difference is 100 × (n 301 -n 100 ) / n 100 The lower limit may be around -10%, -8%, -6%, or -5%, and the upper limit may be around -2%, -4%, or -4.5%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0107] In the case of a structure like that shown in Figure 3, the refractive index n of the substrate 100 is 100 The refractive index n of the second light absorption layer 302 relative to 302 The difference is 100 × (n 302 -n 100 ) / n 100The lower limit may be around 2%, 4%, or 6%, and the upper limit may be around 10%, 9%, 8%, or 7%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0108] In the above structure, the transmittance control layer 200 may be located on the surface of the substrate 100 opposite to the surface on which the first light absorption layer 301 is formed, or, as shown in Figure 3, on the surface of the second light absorption layer 302 opposite to the surface on which the first light absorption layer 301 is formed.

[0109] In such cases, the refractive index n of the substrate 100 The refractive index n of the above transmittance control layer relative to the refractive index n 200 The difference is 100 × (n 200 -n 100 ) / n 100 The lower limit may be around -10%, -8%, -6%, or -5%, and the upper limit may be around -2% or -4%. The difference in refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0110] When a structure containing two types of light-absorbing layers, as shown in Figure 3, has the refractive index relationship described above, an optical filter that ensures the desired transmittance can be obtained.

[0111] As described above, there are no particular limitations on the method for controlling the refractive index relationship of the light absorption layer, substrate, transmittance control layer, adhesive layer, etc. For example, from among the materials that are generally known to be able to form the above-mentioned light absorption layer, substrate, transmittance control layer, adhesive layer, etc., an appropriate material can be selected according to the purpose, and the refractive index can be adjusted by applying low-refractive-index particles (e.g., hollow particles) and / or high-refractive-index particles (e.g., TiO2) that can ensure low refraction, if necessary, to ensure high refraction.

[0112] Although not particularly limited, in the above structure, the second light absorption layer and the first light absorption layer may be in direct contact with each other, the first light absorption layer and the substrate may be in direct contact with each other, and the transmittance control layer may be in direct contact with the second light absorption layer or the substrate.

[0113] The optical filter described above may include a first layer, a second layer, a third layer, and a fourth layer that are stacked sequentially.

[0114] In the above structure, one of the first to fourth layers is the substrate described above, and one of the first to fourth layers may be the transmittance control layer. In addition, in the above structure, the layer among the first to fourth layers that is not the substrate and the transmittance control layer may be the light absorption layer, adhesive layer, bonding layer and / or primer layer described above.

[0115] The structure described above may also be a laminated structure in the form shown in Figure 1 or Figure 2.

[0116] Therefore, in one example, the first or second layer in the above structure may be the light-absorbing layer described above, the second or third layer may be the adhesive layer described above, the third or fourth layer may be the substrate described above, and the first or fourth layer may be the transmittance control layer described above. The details of the light-absorbing layer, substrate, transmittance control layer, adhesive layer, etc. are as described above.

[0117] In the structure described above, the relationship between the refractive indices of each layer can be controlled.

[0118] For example, if the refractive index of the first layer is n1, the refractive index of the second layer is n2, the refractive index of the third layer is n3, and the refractive index of the fourth layer is n4, then the refractive indices n1 to n4 can satisfy the relationship shown in equation 4 or equation 5 below.

[0119] [Formula 4] n2 > n1 ≥ n3 > n4

[0120] [Formula 5] n2>n3≧n1>n4

[0121] In the structure described above, the lower limit of the average refractive index of the first to fourth layers (arithmetic mean of n1, n2, n3, and n4) may be around 1.3, 1.4, or 1.5, and the upper limit may be around 1.9, 1.8, 1.7, or 1.6. The average refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0122] In the above case, the lower limit of the absolute value of the difference between the average refractive indices of the first and third layers (arithmetic mean of n1 and n3) and the average refractive indices of the second and fourth layers (arithmetic mean of n2 and n4) may be around 0, 0.1, 0.2, 0.3, 0.4, or 0.5, and the upper limit may be around 2, 1.5, 1, 0.5, 0.4, 0.3, 0.2, or 0.1. The above difference may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0123] By selecting and arranging layers to satisfy this relationship, an optical filter with the desired characteristics can be obtained.

[0124] In other examples, an optical filter including the first to fourth layers described above can satisfy the relationship of formula 6 or formula 7 below. In the above structure, any one of the first to fourth layers may be the substrate described above, and any one of the first to fourth layers may be the transmittance control layer described above. In addition, in the above structure, any layer among the first to fourth layers that is not the substrate or the transmittance control layer may be the light absorption layer, adhesive layer, bonding layer and / or primer layer described above.

[0125] An optical filter that satisfies Equation 6 or Equation 7 may be the optical filter illustrated in Figure 3. Therefore, in the above case, the first layer may be the transmittance control layer, the second and third layers may be the light absorption layers, and the fourth layer may be the substrate.

[0126] [Formula 6] n v -n1>0, n v -n²<0, n v -n3>0 and n v -n4<0

[0127] [Formula 7] n v -n1<0, n v -n²>0, n v -n3<0 and n v -n4>0

[0128] In equations 6 and 7 above, n1, n2, n3, and n4 are the refractive indices of the first, second, third, and fourth layers, respectively, and n v This may be the arithmetic mean of n1, n2, n3, and n4 as described above.

[0129] The above vThe lower limit may be around 1.3, 1.4, or 1.5, and the upper limit may be around 1.9, 1.8, 1.7, or 1.6. The above average refractive index may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0130] Also, the above n v -n1, n v -n2, n v -n3 and n v The lower bound of each range of -n4 may be approximately 0, 0.01, 0.02, 0.03, 0.04, 0.05, or 0.05 for positive numbers, and its upper bound may be approximately 1, 0.5, 0.1, 0.09, 0.08, 0.07, or 0.065. The above range may be greater than or greater than any one of the lower bounds mentioned above, or less than or equal to any one of the upper bounds mentioned above, or greater than or greater than any one of the lower bounds mentioned above and less than or equal to any one of the upper bounds mentioned above.

[0131] Also, the above n v -n1, n v -n2, n v -n3 and n v The lower limit of each range of -n4 may be approximately -1, -0.5, -0.1, -0.05, or -0.03 if it is a negative number, and the upper limit may be approximately 0, -0.5, -0.3, -0.1, -0.05, or -0.03. The above range may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0132] By selecting and arranging layers to satisfy this relationship, an optical filter with the desired characteristics can be obtained.

[0133] The optical filter of this application can exhibit outstanding optical properties.

[0134] For example, the optical filter described above can exhibit a transmission band with a T50% cut-off wavelength in the range of approximately 380 nm to 425 nm. The T50% cut-off wavelength is the shortest wavelength among those exhibiting 50% transmittance within the wavelength range of 350 nm to 425 nm. There may be one or more wavelengths exhibiting 50% transmittance within the range of 380 nm to 425 nm. If there is one such wavelength, that wavelength is the T50% cut-off wavelength; if there are two or more such wavelengths, the shortest wavelength among them is the T50% cut-off wavelength. The T50% cut-off wavelength can be further adjusted within the range of 385 nm or more, 390 nm or more, 395 nm or more, 400 nm or more, 405 nm or more, or 410 nm or more, and / or within the range of 420 nm or less, 415 nm or less, 410 nm or less, 405 nm or less, or 400 nm or less.

[0135] The above optical filter can exhibit a transmission band with a T50% cutoff wavelength in the range of approximately 590 nm to 680 nm. The above T50% cutoff wavelength is the longest wavelength among the wavelengths that exhibit 50% transmittance within the wavelength range of 560 nm to 700 nm. There may be one or more wavelengths exhibiting 50% transmittance within the range of 560 nm to 700 nm. If there is one, that wavelength is the T50% cutoff wavelength; if there are two or more, the longest wavelength is the T50% cutoff wavelength. The above T50% cutoff wavelength can be further adjusted within the range of 600 nm or more, 610 nm or more, 620 nm or more, 630 nm or more, or 640 nm or more and / or within the range of 670 nm or less, 660 nm or less, 650 nm or less, or 640 nm or less.

[0136] The lower limit of the average transmittance of the above optical filter within the range of 425nm to 465nm may be around 70% or 75%, and the upper limit may be around 100%, 95%, 90%, 85%, or 80%. The above transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0137] The lower limit of the average transmittance of the above optical filter in the range of 466 nm to 480 nm may be approximately 70%, 75%, 80%, or 85%, and the upper limit may be approximately 100%, 95%, or 90%. The above transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0138] The lower limit of the average transmittance of the above optical filter in the range of 481 nm to 560 nm may be approximately 70%, 75%, 80%, 85%, or 90%, and the upper limit may be approximately 100%, 95%, or 90%. The above transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0139] The lower limit of the average transmittance of the above optical filter in the range of 850nm to 1050nm may be approximately 0%, 5%, 15%, 20%, or 25%, and the upper limit may be approximately 30%, 25%, 20%, 15%, 10%, 5%, or 1%. The above transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0140] The lower limit of the transmittance of the optical filter at 950 nm may be approximately 0%, 5%, 15%, 20%, or 25%, and the upper limit may be approximately 30%, 25%, 20%, 15%, 10%, 5%, 1%, or 0.5%. The transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0141] The lower limit of the transmittance of the optical filter at 1050 nm may be approximately 0%, 5%, or 15%, and the upper limit may be approximately 20%, 15%, 10%, 5%, 1%, or 0.5%. The transmittance may be greater than or greater than any one of the lower limits mentioned above, or less than or equal to any one of the upper limits mentioned above, or greater than or greater than any one of the lower limits mentioned above and less than or equal to any one of the upper limits mentioned above.

[0142] The optical filter of this application can exhibit any one or more combinations of the above optical properties, and preferably can satisfy all of the above optical properties.

[0143] This application also relates to an imaging device including the optical filter described above. In this case, the configuration of the imaging device and the method of applying the optical filter are not particularly limited, and known configurations and application methods can be applied.

[0144] Furthermore, the applications of the optical filter of this application are not limited to the imaging device described above, but can be applied to a variety of other applications requiring near-infrared filtering (for example, display devices such as PDPs). [Effects of the Invention]

[0145] This application can provide an optical filter and its applications. This application can provide an optical filter and its applications that can effectively block unwanted wavelengths of light (e.g., ultraviolet and infrared light) while ensuring high transmittance in the desired wavelength range (e.g., the visible light range). [Brief explanation of the drawing]

[0146] Figures 1 to 3 show exemplary structures of the optical filter of this application. Figure 4 shows the transmittance characteristics of the optical filter of Example 8. Figure 5 shows the transmittance characteristics of the optical filter of Example 9. [Modes for carrying out the invention]

[0147] The optical filters of this application will be described in detail below based on the following examples, but the scope of the optical filters of this application is not limited by the following examples.

[0148] 1. Evaluation of transmittance The transmittance was measured using a spectrophotometer (manufacturer: Perkinelmer, product name: Lambda750 spectrophotometer) on test specimens obtained by cutting the material to 10 mm in width and 10 mm in height, respectively. The transmittance was measured at different wavelengths and angles of incidence according to the manual for the above-mentioned instrument. The test specimen was positioned on a straight line between the measurement beam and the detector of the spectrophotometer, and the transmittance was checked while changing the angle of incidence of the measurement beam from 0 degrees to 40 degrees. Unless otherwise specified, the transmittance results in this embodiment refer to the results when the angle of incidence is 0 degrees. An angle of incidence of 0 degrees is a direction substantially parallel to the surface normal direction of the test specimen.

[0149] In terms of transmittance, the average transmittance or average reflectance within a predetermined wavelength range is the result of calculating the arithmetic mean of the transmittances measured for each wavelength while increasing the wavelength by 1 nm from the shortest wavelength within the above wavelength range. The minimum transmittance is the lowest transmittance among the transmittances measured while increasing the wavelength by 1 nm. For example, the average transmittance in the wavelength range of 350 nm to 360 nm is the arithmetic mean of the transmittances measured at wavelengths of 350 nm, 351 nm, 352 nm, 353 nm, 354 nm, 355 nm, 356 nm, 357 nm, 358 nm, 359 nm, and 360 nm, and the minimum transmittance within the wavelength range of 350 nm to 360 nm is the lowest transmittance among the transmittances measured at wavelengths of 350 nm, 351 nm, 352 nm, 353 nm, 354 nm, 355 nm, 356 nm, 357 nm, 358 nm, 359 nm, and 360 nm.

[0150] 2. Evaluation of copper content The copper content of the glass substrate was confirmed using an X-ray fluorescence spectrometer (WD XRF, Wavelength Dispersive X-Ray Fluorescence Spectrometry). When the test specimen (glass substrate) is irradiated with X-rays using the above apparatus, characteristic secondary X-rays are generated from the individual elements of the specimen, and the apparatus detects these secondary X-rays according to the wavelength of each element. The intensity of the secondary X-rays is proportional to the elemental content, and therefore, quantitative analysis can be performed using the intensity of the secondary X-rays measured according to the wavelength of the element.

[0151] 3. Evaluation of refractive index The refractive index was measured at a wavelength of 520 nm using an ATAGO measuring instrument (ATAGO, NAR-4T).

[0152] Manufacturing Example 1. Manufacturing of Absorbent Layer Material A Absorbent layer material A was manufactured by dispersing a dye and a binder resin (polyacrylate-based, Sumitomo, Sumipex) in a solvent (MEK, Methyl Ethyl Ketone). In the above process, the mixing ratio of the binder resin, dye, and solvent was approximately 1.54:0.2:8.44 by weight (binder resin:dye:solvent).

[0153] The above dyes used were a mixture of dye 1 (IRA1032, Exciton, diimmonium compound, absorption maximum wavelength range: 900nm~1200nm), dye 2 (IRA705, Exciton, squarylium compound, absorption maximum wavelength range: 700nm~800nm), and dye 3 (ADA3232, HW.SANDS, absorption maximum wavelength range: 300nm~400nm). The above dye mixture contained the three dyes in a weight ratio of 3.8:3.3:2.9 (dye 1: dye 2: dye 3).

[0154] The absorbent layer material A can be coated using an appropriate method and then heat-treated (at approximately 135°C for approximately 2 hours) to form the absorbent layer.

[0155] For example, the refractive index of an absorption layer formed using the above-mentioned absorption layer material A can be evaluated by coating the absorption layer material A onto a substrate (glass substrate) with a spin coater, curing it at 135°C for about 2 hours to form an absorption layer with a thickness of about 3.5 μm, and then evaluating the refractive index of the absorption layer using the method described above. The refractive index evaluated using this method was about 1.53.

[0156] Manufacturing Example 2. Manufacturing of Absorbent Layer Material B Absorbent layer material B can be produced by dispersing dye 1 and binder resin from Production Example 1 in a solvent (MEK, Methyl Ethyl Ketone). In the above example, siloxane oligomer (a partially hydrolyzed condensate of 3-glycidoxypropyltrimethoxysilane) was used as the binder resin. In the above example, the mixing ratio of the absorbent, binder resin, and solvent was approximately 1:75:24 by weight (dye:binder resin:solvent).

[0157] The absorbent layer can be formed by coating with the above-mentioned absorbent layer material B and heat-treating it (at approximately 140°C for approximately 2 hours).

[0158] For example, the refractive index of an absorption layer formed with the above-mentioned absorption layer material B was evaluated by coating a glass substrate with material B using a spin coater, maintaining the temperature at 140°C for 2 hours to form an absorption layer with a thickness of approximately 5 μm. The refractive index evaluated by this method was approximately 1.45.

[0159] Manufacturing Example 3. Manufacturing of Absorbent Layer Material C Absorbent layer material C was prepared by dispersing a dye and a binder resin (Polyimide) in a solvent (GBL, gamma butyrolactone). The mixing ratio of the dye, binder resin, and solvent was approximately 0.1:70:29.9 by weight (dye:binder resin:solvent). The dye used was a mixture of dye 2 and dye 3 from Production Example 1, mixed in a weight ratio of 4.9:5.1 (dye 2:dye 3).

[0160] The absorbent layer material C described above can be coated using an appropriate method and then heat-treated (at approximately 140°C for approximately 2 hours) to form the absorbent layer.

[0161] The above absorption layer material C was coated onto a glass substrate using a spin coater and maintained at 140°C for 2 hours to form an absorption layer with a thickness of approximately 6 μm. The refractive index of this absorption layer was then evaluated. The refractive index evaluated by this method was approximately 1.62.

[0162] Example 1. A resin layer (transmittance control layer) was formed on both sides of a glass substrate (thickness: approximately 0.21 mm) with a refractive index of approximately 1.52. The resin layer (transmittance control layer) was manufactured using a coating solution prepared by mixing a solvent (dibutyl ether) and inorganic polysilazane (manufacturer: Sanwa Chemical, product name: 1035) in a weight ratio of 9.5:0.5 (solvent: inorganic polysilazane). The coating solution was spin-coated onto the glass substrate and maintained at 140°C for 2 hours to form a resin layer (transmittance control layer) with a thickness of approximately 20 nm. The refractive index of the resin layer (transmittance control layer) was approximately 1.45.

[0163] The above-described resin layer (transmittance control layer) was formed on both sides of the glass substrate.

[0164] Example 2. As the glass substrate, the same glass substrate as in Example 1 was used, and a resin layer (transmittance control layer) was formed on one surface of the glass substrate. The resin layer (transmittance control layer) was manufactured using a coating solution prepared by mixing a solvent (Dibutyl ether) and an organic polysilazane (manufacturer: Sanwa Chemical, product name: 1001-5) in a weight ratio of 9.5:0.5 (solvent:organic polysilazane). The coating solution was spin-coated onto the glass substrate and maintained at 140°C for approximately 2 hours to form the resin layer (transmittance control layer) with a thickness of approximately 76 nm. The refractive index of the resin layer (transmittance control layer) was approximately 1.45.

[0165] Example 3. A resin layer (transmittance control layer) was formed on both sides of a glass substrate using the coating solution from Example 2. The method for forming the resin layer was the same as in Example 2, and the same glass substrate as in Example 2 was used.

[0166] The evaluation results for Examples 1-3 are summarized in Table 1 below. In Table 1, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also in Table 1, the refractive index is the refractive index of the resin layer (transmittance control layer) formed in each example, and Ref is the transmittance of the glass substrate itself used in Examples 1-3.

[0167] [Table 1]

[0168] Based on the results in Table 1, the percentage increase or decrease (in %) of the transmittance Tmin and Tave for each example was confirmed and summarized in Table 2 below. The above percentage increase or decrease was calculated using the formula 100 × (T2 - T1) / T1, where T1 is the transmittance Ref of the glass substrate and T2 is the transmittance of the glass substrate on which the resin layer (transmittance control layer) is formed.

[0169] [Table 2]

[0170] The results in Tables 1 and 2 show that in Examples 1 to 3, the resin layer (transmittance control layer) ensures a higher transmittance compared to the transmittance of the glass substrate itself.

[0171] Example 4. As the transparent substrate, a phosphate-based infrared-absorbing glass substrate (HOYA Corporation, thickness: approximately 0.21 mm) having infrared absorption properties was used. The copper content measured in the above infrared-absorbing glass substrate was approximately 2.89% by weight. A resin layer (transmittance control layer) was formed on one surface of the above glass substrate using the same coating solution as used in Example 2. In this case, the resin layer was formed in the same manner as in Example 2, and its thickness was also adjusted to be the same.

[0172] Example 5 A resin layer (transmittance control layer) was formed on both sides of the same transparent substrate used in Example 4 using the same method as in Example 3.

[0173] The evaluation results for Examples 4 and 5 are summarized in Table 3 below. In Table 3, Tmin is the minimum transmittance in the relevant wavelength range (unit: %), and Tave is the average transmittance in the relevant wavelength range (unit: %). Also in Table 3, Ref is the transmittance of the glass substrate itself used in Examples 7 and 8. Also in Table 3, the increase / decrease rate is the result calculated by formula 100 × (T2 - T1) / T1, where T1 is the transmittance Ref of each glass substrate and T2 is the transmittance of each glass substrate on which the resin layer is formed, and the unit is %.

[0174] [Table 3]

[0175] Example 6. As the glass substrate, a phosphate-based infrared absorbing glass substrate (HOYA Corporation, thickness: approximately 0.21 mm, refractive index: approximately 1.57, copper content: 9.5% by weight) having infrared absorption properties was used. The resin layer (transmittance control layer) was manufactured using the same coating solution as used in Example 2. The refractive index of the resin layer formed with the coating solution was evaluated in the same way as in Example 2, and the refractive index of the resin layer was found to be approximately 1.45. The coating solution was coated onto one surface of the glass substrate by spin coating and maintained at 140°C for approximately 2 hours to form a resin layer with a thickness of approximately 76 nm.

[0176] Example 7. The resin layer was formed in the same manner as in Example 6, except that after spin coating, the maintenance temperature of the coating solution was set to 90°C and the resin layer was formed to a thickness of approximately 70 nm.

[0177] The evaluation results for Examples 6 and 7 are summarized in Table 4 below. In Table 4, Tmin is the minimum transmittance in the relevant wavelength range (unit: %), and Tave is the average transmittance in the relevant wavelength range (unit: %). Also in Table 4, Ref is the transmittance of the glass substrate itself used in Examples 9 and 10. Also in Table 4, the increase / decrease rate is the result calculated by formula 100 × (T2 - T1) / T1, where T1 is the transmittance Ref of each glass substrate and T2 is the transmittance of each glass substrate on which the resin layer is formed, and the unit is %.

[0178] [Table 4]

[0179] As shown in Table 4, although both Examples 6 and 7 used the same type of material to form the resin layer (transmittance control layer), Example 6, with a curing temperature of 140°C, showed superior performance compared to Example 7, with a curing temperature of 90°C. This result is attributed to the difference in curing temperature causing a difference in the degree of curing of the resin layer, which resulted in the formation of a layer with a different refractive index in Example 7 compared to Example 6.

[0180] Example 8 The same glass substrate as in Example 2 was used, and a resin layer (transmittance control layer) was formed on one surface of the glass substrate. The resin layer was formed using the coating solution applied in Example 2. The method of forming the resin layer and its thickness were the same as in Example 2.

[0181] Next, an adhesive layer and an absorption layer were sequentially formed on the surface of the glass substrate where the resin layer (transmittance control layer) was not formed, thereby manufacturing an optical filter.

[0182] The above adhesive layer was formed to a thickness of approximately 170 nm using a known acrylic adhesive. The refractive index of this adhesive layer was approximately 1.60. The adhesive used to form the above adhesive layer was spin-coated onto a glass substrate and maintained at 140°C for approximately 30 minutes to form the adhesive layer. Next, the absorption layer material A from Manufacturing Example 1 was spin-coated onto the above adhesive layer and maintained at 135°C for approximately 2 hours to form an absorption layer with a thickness of approximately 3.5 μm.

[0183] Figure 4 shows the transmittance characteristics of the optical filter described above. (In this figure, the x-axis represents wavelength (nm) and the y-axis represents transmittance (%)). The dotted line in this figure represents the results for the optical filter before the resin layer (high transmittance layer) was formed, and the solid line represents the results for the optical filter of Example 8 described above.

[0184] Table 5 shows the evaluation results for the optical filters described above. In Table 5, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also, in Table 5, Ref is the value for optical filters without a resin layer (transmittance control layer) (i.e., filters with an absorption layer / adhesive layer / glass substrate structure). In Table 5, T50%cut on is the shortest wavelength (in nm) showing 50% transmittance in the 350nm to 425nm wavelength range, T50%cut off is the longest wavelength (in nm) showing 50% transmittance in the 600nm to 900nm wavelength range, and T10%cut off is the longest wavelength (in nm) showing 10% transmittance in the 600nm to 900nm wavelength range.

[0185] [Table 5]

[0186] Example 9 The same glass substrate as in Example 2 was used as the glass substrate. An optical filter was manufactured by sequentially forming a first absorption layer using the material from Manufacturing Example 2, a second absorption layer using the material from Manufacturing Example 3, and a resin layer (transmittance control layer) on one surface of the glass substrate (i.e., a structure of glass substrate / first absorption layer / second absorption layer / resin layer).

[0187] The first absorption layer was formed by spin-coating the absorption layer material of Manufacturing Example 2 onto the glass substrate and maintaining it at 140°C for about 2 hours to a thickness of about 5 μm. The second absorption layer was formed by spin-coating the absorption layer material of Manufacturing Example 3 onto the first absorption layer and maintaining it at 140°C for about 2 hours to a thickness of about 6 μm.

[0188] Next, a resin layer (transmittance control layer) of the same thickness was formed on the second absorption layer using the same method as in Example 2.

[0189] Figure 5 shows the transmittance characteristics of the optical filter manufactured above (in this figure, the x-axis is wavelength (nm) and the y-axis is transmittance (%)). The dotted line in this figure represents the results for the optical filter before the resin layer (transmittance control layer) was formed, and the solid line represents the results for the optical filter of Example 9 above.

[0190] Table 6 below shows the evaluation results for the optical filter described above. In Table 6, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also, in Table 6, Ref is the value for an optical filter without a resin layer (transmittance control layer) (i.e., a filter with a second absorption layer / first absorption layer / glass substrate structure).

[0191] In Table 6 below, T50% cut on is the shortest wavelength (in nm) that shows 50% transmittance in the wavelength range of 350 nm to 425 nm, T50% cut off is the longest wavelength (in nm) that shows 50% transmittance in the wavelength range of 600 nm to 900 nm, and T10% cut off is the longest wavelength (in nm) that shows 10% transmittance in the wavelength range of 600 nm to 900 nm.

[0192] [Table 6]

[0193] Example 10 An optical filter was manufactured by forming a dielectric multilayer film on both sides of the optical filter of Example 9. The dielectric multilayer film was formed by depositing a sublayer using the ion-beam assisted deposition method. During deposition, the vacuum and temperature conditions were set to 5.0E-5 Torr and 120°C, respectively, and the IBS (Ion Beam Sputtering) source voltage was set to 350V and the current to 850mA. Using the above method, a dielectric multilayer film was formed by alternately forming a TiO2 layer (refractive index approximately 2.61) as a high refractive index layer and an SiO2 layer (refractive index approximately 1.46) as a low refractive index layer.

[0194] Table 7 below shows the thickness of each sublayer of the dielectric multilayer film formed on the surface of the resin layer (transmittance control layer) of the optical filter, and Table 8 shows the thickness of each sublayer formed on the surface of the glass substrate of the optical filter opposite to the surface on which the resin layer (transmittance control layer) is formed.

[0195] In Tables 7 and 8, number 1 is the first layer formed on the resin layer (transmittance control layer) or glass substrate.

[0196] [Table 7]

[0197] [Table 8]

[0198] Table 9 below shows the evaluation results for the above optical filter. In Table 9, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also, in Table 9, Ref is the value for an optical filter without a resin layer (transmittance control layer) (i.e., a filter with the structure of dielectric multilayer film / second absorption layer / first absorption layer / glass substrate / dielectric multilayer film).

[0199] In Table 9, T50% cut on is the shortest wavelength (in nm) that shows 50% transmittance in the wavelength range of 350 nm to 425 nm, T50% cut off is the longest wavelength (in nm) that shows 50% transmittance in the wavelength range of 600 nm to 900 nm, and T10% cut off is the longest wavelength (in nm) that shows 10% transmittance in the wavelength range of 600 nm to 900 nm.

[0200] [Table 9]

[0201] Example 11. A resin layer (transmittance control layer) was formed on one surface of a glass substrate using the same method as in Example 6. The same materials as in Example 9 were used for the glass substrate and the resin layer. However, during the spin coating of the coating solution to form the resin layer, the rotation speed was controlled to approximately 1500 rpm so that the thickness of the resin layer was approximately 75.9 nm. Except for the change in the thickness of the resin layer, the method of forming the resin layer was the same as in Example 6.

[0202] Example 12. A resin layer (transmittance control layer) was formed on one surface of a glass substrate using the same method as in Example 6. The same materials as in Example 6 were used for the glass substrate and the resin layer. However, during the spin coating of the coating solution to form the resin layer, the rotation speed was controlled to approximately 1050 rpm so that the thickness of the resin layer was approximately 121 nm.

[0203] Example 13. A resin layer (transmittance control layer) was formed on one surface of a glass substrate using the same method as in Example 6. The same materials as in Example 6 were used for the glass substrate and the resin layer. However, during the spin coating of the coating solution to form the resin layer, the rotation speed was controlled to approximately 2000 rpm. In this case, the resin layer was formed very thinly, making it impossible to measure its thickness.

[0204] Table 10 below shows the evaluation results for Examples 11-13, where Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. In Table 10 below, Ref is the value for a glass substrate without a resin layer (transmittance control layer).

[0205] [Table 10]

[0206] Example 14. A resin layer (transmittance control layer) was formed on one surface of the same glass substrate used in Example 6. The resin layer was formed by spin-coating a coating solution prepared by mixing DBE (Dibutyl ether) and inorganic polysilazane (manufacturer: DNF, product name: DHC-19D) in a weight ratio of 8.1:1.9 (DBE: inorganic polysilazane), and maintaining the temperature at 140°C for approximately 2 hours. During the spin-coating process, the rotation speed was controlled to approximately 1700 rpm to ensure that the thickness of the resin layer was approximately 29.6 nm.

[0207] Example 15. A resin layer (transmittance control layer) was formed on one surface of the same glass substrate used in Example 6. The same material as in Example 14 was used to form the resin layer. During spin coating of the coating solution to form the resin layer, the rotation speed was controlled to approximately 1800 rpm so that the thickness of the resin layer was approximately 27.1 nm. Except for the change in the thickness of the resin layer, the method of forming the resin layer was the same as in Example 14.

[0208] Example 16. A resin layer (transmittance control layer) was formed on one surface of the same glass substrate used in Example 6. The same material as in Example 14 was used to form the resin layer. However, during the spin coating of the coating solution to form the resin layer, the rotation speed was controlled to approximately 2000 rpm so that the thickness of the resin layer was approximately 25.1 nm. Except for the change in the thickness of the resin layer, the method of forming the resin layer was the same as in Example 14.

[0209] Table 11 shows the results for Examples 14-16 described above. In Table 11, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also, in Table 11 below, Ref is the value for a glass substrate in which no resin layer (transmittance control layer) is formed.

[0210] [Table 11]

[0211] Example 17. A resin layer (transmittance control layer) was formed on one surface of the same glass substrate used in Example 6. The same material as in Example 1 was used to form the resin layer. However, during the spin coating of the coating solution for forming the resin layer, the rotation speed was controlled to approximately 1500 rpm. Except for the change in the rotation speed during the spin coating of the resin layer, the method for forming the resin layer was the same as in Example 1.

[0212] Example 18. A resin layer (transmittance control layer) was formed on one surface of the same glass substrate used in Example 6. The same material as in Example 1 was used to form the resin layer. However, during the spin coating of the coating solution for forming the resin layer, the rotation speed was controlled to approximately 1700 rpm. Except for the change in the rotation speed during the spin coating of the resin layer, the method for forming the resin layer was the same as in Example 1.

[0213] Table 12 shows the evaluation results for Examples 17 and 18 described above. In Table 12, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also, in Table 12 below, Ref is the value for a glass substrate in which no resin layer (transmittance control layer) is formed.

[0214] [Table 12]

[0215] Example 19 As the glass substrate, the same glass substrate as in Example 2 was used, and a resin layer (transmittance control layer) was formed on one surface of the glass substrate. In this case, the resin layer was formed using the coating solution applied in Example 2. The method of forming the resin layer and the thickness of the formed layer were the same as in Example 2. However, during spin coating of the coating solution, the rotation speed was adjusted to approximately 1050 rpm to adjust the final thickness of the resin layer to approximately 121 nm. Next, an adhesive layer and an absorption layer were sequentially formed on the surface of the glass substrate where the resin layer (transmittance control layer) was not formed, and an optical filter was manufactured. The adhesive layer and absorption layer were formed in the same manner as in Example 8.

[0216] The evaluation results for Example 19 are summarized in Table 13 below. In Table 13, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also in Table 13, Ref is the transmittance for an optical filter without a resin layer (transmittance control layer).

[0217] Furthermore, in Table 13 below, the numbers in parentheses represent the percentage increase or decrease compared to the reference (in %).

[0218] [Table 13]

[0219] Example 20 An optical filter with the same structure as in Example 9 (glass substrate / first absorption layer / second absorption layer / resin layer) was manufactured. The optical filter was manufactured using the same materials and method as in Example 9, except that the rotation speed was adjusted to approximately 1050 rpm during spin coating of the coating solution for forming the resin layer, so that the final resin layer thickness was approximately 121 nm.

[0220] Examples 21-28 The optical filter was formed in the same manner as in Example 20, except that the rotation speed of the spin coating and the thickness of the resin layer were changed as shown in Table 14 below. In Example 28, the resin layer was formed very thinly, making it difficult to measure the thickness accurately.

[0221] [Table 14]

[0222] The evaluation results for Examples 20-28 described above are summarized in Table 15 below. In Table 15, Tmin is the minimum transmittance (in %) in the relevant wavelength range, and Tave is the average transmittance (in %) in the relevant wavelength range. Also in Table 15, Ref is the transmittance for an optical filter without a resin layer (transmittance control layer).

[0223] [Table 15]

[0224] The results of Table 15, converted to percentage increase / decrease relative to Ref (in %), are shown in Table 16 below.

[0225] [Table 16]

[0226] Example 29 An optical filter was manufactured by forming an optical filter in the same manner as in Example 20, but with a change in the stacking order of the optical filters. Specifically, the structure of the optical filter in Example 20, which had a glass substrate / first absorption layer / second absorption layer / resin layer structure, was changed to form an optical filter with a resin layer / glass substrate / first absorption layer / second absorption layer structure. Except for the change in the stacking order as described above, the materials and formation methods for each layer were the same as in Example 20.

[0227] Examples 30-37 The optical filter was formed in the same manner as in Example 29, except that the rotation speed of the spin coating and the thickness of the resin layer were changed as shown in Table 17 below. In Example 37, the resin layer was formed very thinly, making it difficult to measure the thickness accurately.

[0228] [Table 17]

[0229] The evaluation results for Examples 29 to 37 are organized and presented in Table 18 below. In Table 18 below, Tmin is the minimum transmittance (unit: %) in the relevant wavelength region, and Tave is the average transmittance (unit: %) in the relevant wavelength region. Further, in Table 18 below, Ref is the transmittance with respect to an optical filter on which no resin layer (transmittance control layer) is formed.

[0230] [Table 18]

[0231] The results obtained by converting the results in Table 18 into a Ref comparison increase / decrease rate (unit: %) are as shown in Table 19 below.

[0232] [Table 19]

Claims

1. A substrate having a first surface and a second surface opposite to the first surface, A transmittance control layer formed on the first surface of the substrate, The substrate includes a light-absorbing layer formed on the second surface of the substrate, which has an absorbent and a transparent resin, The substrate contains copper in an amount of 1% by weight or more and 10% by weight or less. The absolute value of the difference between the refractive index of the substrate and the refractive index of the transmittance control layer is within the range of 2% to 10%. ΔT in equation 1 below １ However, it is an optical filter with a filtration efficiency of 0.5% or more. [Formula 1] ΔT １ =100×(T Ｆ１ -T Ｓ１ ) / T Ｓ１ In formula 1, T Ｆ１ This is the average transmittance of the optical filter in the wavelength range of 481 nm to 560 nm, and T Ｓ１ This is the average transmittance of the optical filter without the transmittance control layer in the wavelength range of 481 nm to 560 nm.

2. A substrate having a first surface and a second surface opposite to the first surface, A transmittance control layer formed on the second surface of the substrate, The substrate includes a light-absorbing layer having an absorbent and a transparent resin, which is formed between the second surface of the substrate and the transmittance control layer. The substrate contains copper in an amount of 1% by weight or more and 10% by weight or less, and the absolute value of the difference between the refractive index of the substrate and the refractive index of the transmittance control layer is in the range of 2% to 10%. ΔT in equation 1 below １ However, it is an optical filter with a filtration efficiency of 0.5% or more. [Formula 1] ΔT １ =100×(T Ｆ１ -T Ｓ１ ) / T Ｓ１ In formula 1, T Ｆ１ This is the average transmittance of the optical filter in the wavelength range of 481 nm to 560 nm, and T Ｓ１ This is the average transmittance of the optical filter without the transmittance control layer in the wavelength range of 481 nm to 560 nm.

3. T in formula 1 above Ｆ１ The optical filter according to claim 1 or 2, wherein the amount is 80% or more.

4. The optical filter according to claim 1 or 2, wherein the transmittance control layer comprises one or more selected from the group consisting of cyclic olefin resin, polyarylate, polyisocyanate, polyimide, polyetherimide, polyamideimide, polyacrylate, polyester, polysulfone, polysilazane, and polysiloxane.

5. The optical filter according to claim 1 or 2, wherein the refractive index of the substrate is greater than that of the transmittance control layer, and the refractive index of the substrate is in the range of 1.48 to 1.

6.

6. The substrate further includes a second transmittance control layer on the second surface, The light-absorbing layer is located between the substrate and the second transmittance control layer. The absolute value of the difference between the refractive index of the substrate and the refractive index of the second transmittance control layer is within the range of 2% to 10%. ΔT in equation 2 below ２ However, it is 0.5% or more. [Formula 2] ΔT ２ =100×(T Ｆ１ -T Ｓ２ ) / T Ｓ２ In formula 2, T Ｆ１ This is the average transmittance of the optical filter in the wavelength range of 481 nm to 560 nm, and T Ｓ２ This is the average transmittance of the optical filter without the second transmittance control layer in the wavelength range of 481 nm to 560 nm. The optical filter according to claim 1.

7. A second transmittance control layer is provided on the first surface of the substrate, The substrate and the second transmittance control layer further include a second light absorption layer having an absorbent and a transparent resin, The absolute value of the difference between the refractive index of the substrate and the refractive index of the second transmittance control layer is within the range of 2% to 10%. The ΔT² in equation 2 below is 0.5% or more. [Formula 2] ΔT ２ =100×(T Ｆ１ -T Ｓ２ ) / T Ｓ２ In formula 2, T Ｆ１ This is the average transmittance of the optical filter in the wavelength range of 481 nm to 560 nm, and T Ｓ２ This is the average transmittance of the optical filter without the second transmittance control layer in the wavelength range of 481 nm to 560 nm. The optical filter according to claim 2.

8. The optical filter according to claim 1 or 2, wherein the absolute value of the difference between the refractive index of the light-absorbing layer and the refractive index of the substrate is in the range of 0.2% to 10%.

9. The optical filter according to claim 1 or 2, further comprising an adhesive layer, bonding layer or primer layer between the light-absorbing layer and the second surface of the substrate.

10. The difference between the refractive index of the light-absorbing layer and the refractive index of the substrate is within the range of 0.2% to 2%. The difference in refractive index between the substrate and the adhesive layer, bonding layer, or primer layer is within the range of 3% to 10%. The optical filter according to claim 9, wherein the difference in refractive index between the transmittance control layer and the adhesive layer, bonding layer or primer layer is within the range of 8% to 15%.

11. The optical filter according to claim 10, wherein the difference in refractive index of the transmittance control layer with respect to the refractive index of the substrate is within the range of -2% to -10%.

12. The optical filter according to claim 10, wherein the light-absorbing layer and the adhesive layer, bonding layer or primer layer are in direct contact with each other, and the adhesive layer, bonding layer or primer layer and the substrate are in direct contact with each other.

13. The optical filter according to claim 1 or 2, wherein the light-absorbing layer includes a first and a second light-absorbing layer having different refractive indices.

14. The optical filter according to claim 13, wherein the first light-absorbing layer has a lower refractive index than the second light-absorbing layer, and the first light-absorbing layer is formed between the second light-absorbing layer and the substrate.

15. The optical filter according to claim 13, wherein the difference in refractive index of the first light-absorbing layer with respect to the refractive index of the substrate is in the range of -2% to -10%, and the difference in refractive index of the second light-absorbing layer with respect to the refractive index of the substrate is in the range of 2% to 10%.

16. The optical filter according to claim 13, wherein the difference in refractive index of the transmittance control layer with respect to the refractive index of the substrate is within the range of -2% to -10%.

17. The optical filter according to claim 13, wherein the second light-absorbing layer and the first light-absorbing layer are in direct contact with each other, the first light-absorbing layer and the substrate are in direct contact with each other, and the transmittance control layer is in direct contact with the second light-absorbing layer or the substrate.

18. The optical filter according to claim 1 or 2, further comprising a dielectric multilayer film formed on one of the first and second surfaces of the substrate, or on both the first and second surfaces.

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