Optical filter

Abstract

The present invention relates to an optical filter which is provided with a base material, an antireflection layer 1 that is formed of a dielectric multilayer film, and an antireflection layer 2 that is formed of a dielectric multilayer film, wherein: the base material comprises a near-infrared absorbing glass and a resin film that is superposed on at least one main surface of the near-infrared absorbing glass; the resin film contains a resin, a UV dye that has a maximum absorption wavelength of 350 to 410 nm in the resin, and an IR dye that has a maximum absorption wavelength of 700 to 850 nm in the resin; and the optical filter satisfies all of the specific spectral characteristics (i-1) to (i-7).

Description

Optical Filters

[0001] The present invention relates to an optical filter that transmits visible light and blocks near-infrared light.

[0002] In order to reproduce color tones well and obtain clear images, imaging devices using solid-state imaging elements use optical filters that transmit light in the visible range (hereinafter also referred to as "visible light") and block light in the ultraviolet wavelength range (hereinafter also referred to as "ultraviolet light") and light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light").

[0003] Known optical filters include, for example, reflective filters that reflect light to be blocked by utilizing optical interference caused by a dielectric multilayer film, which is made by alternately stacking dielectric thin films with different refractive indices on one or both sides of a transparent substrate. Such optical filters have a problem in that the optical thickness of the dielectric multilayer film changes depending on the angle of incidence of light, resulting in changes in the spectral transmittance curve and spectral reflectance curve depending on the angle of incidence. For example, depending on the number of layers in the multilayer film, interference caused by reflected light at the interfaces between each layer can cause significant changes in the transmittance in the visible light range, known as ripples, which tend to occur more strongly the greater the angle of incidence of light. This causes a change in the amount of light captured in the visible light range at high angles of incidence, resulting in a problem of reduced image reproducibility.

[0004] Furthermore, when the near-ultraviolet light is incident at a high angle of incidence, it can transmit light, resulting in light leakage.Since image sensors are also sensitive to the near-ultraviolet light region, if the near-ultraviolet light blocking properties are insufficient, there is a risk of image quality degradation due to unnecessary light, known as flare or ghosting, occurring in the captured visible light image.

[0005] As described above, with the recent trend toward lower profile camera modules, it is expected that they will be used under high incident angle conditions, and therefore optical filters that are less susceptible to the effects of incident angle are required.

[0006] Here, Patent Document 1 describes an optical filter having both near-ultraviolet light blocking ability and near-infrared light blocking ability, which has a copper phosphonate film formed on a glass substrate. Patent Document 2 describes an optical filter having both near-ultraviolet light blocking ability and near-infrared light blocking ability, which has an absorption layer containing a near-ultraviolet light absorbing dye and a near-infrared light absorbing dye in a transparent resin, and a copper phosphonate film. Patent Document 3 describes an optical filter having both near-ultraviolet light blocking ability and near-infrared light blocking ability, which has an absorption layer containing a near-ultraviolet light absorbing dye and a near-infrared light absorbing dye in a transparent resin.

[0007] Japanese Patent No. 6232161 Japanese Patent No. 6966334 Japanese Patent No. 6939224

[0008] However, the optical filter described in Patent Document 1 has room for improvement in terms of light-blocking properties in the near-ultraviolet region, particularly around a wavelength of 400 nm. The optical filter described in Patent Document 2 has room for improvement in terms of light-blocking properties in the near-ultraviolet region, particularly around a wavelength of 400 nm, and the change in transmittance between the near-ultraviolet light-blocking region and the visible light-transmitting region is gradual, so there is also room for improvement in terms of achieving both light-blocking and transmittance. The optical filter described in Patent Document 3 ensures light-blocking properties only with a near-ultraviolet light-absorbing dye and a near-infrared light-absorbing dye, so a large amount must be used, which raises concerns about a decrease in visible light transmittance.

[0009] An object of the present invention is to provide an optical filter that suppresses ripple in the visible light region even at high angles of incidence, maintains high transmittance of visible light, and has excellent near-infrared and near-ultraviolet light blocking properties, particularly excellent ultraviolet light blocking properties with a wavelength of around 400 nm.

[0010] The present invention provides an optical filter having the following configuration: [1] An optical filter comprising a substrate, an antireflection layer 1 made of a dielectric multilayer film laminated as an outermost layer on one main surface side of the substrate, and an antireflection layer 2 made of a dielectric multilayer film laminated as an outermost layer on the other main surface side of the substrate, wherein the substrate has a near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass, and the resin film contains a resin, a UV dye having a maximum absorption wavelength in the resin at 350 to 410 nm, and an IR dye having a maximum absorption wavelength in the resin at 700 to 850 nm, and the optical filter satisfies all of the following spectral characteristics (i-1) to (i-7): (i-1) An average transmittance T ３５０－３９０（０ｄｅｇ）ＡＶＥ (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is ４００（０ｄｅｇ） (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is 3% or less. ４００（０ｄｅｇ） and transmittance T at a wavelength of 430 nm ４３０（０ｄｅｇ） T satisfies the following relationship ４３０（０ｄｅｇ） -T ４００（０ｄｅｇ） ≧78% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ４３０－６００（０ｄｅｇ）ＡＶＥ (i-5) When the antireflection layer 1 side is the incident direction, the absolute value of the difference between the average reflectance R1430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R1430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-6) When the antireflection layer 2 side is the incident direction, the absolute value of the difference between the average reflectance R2430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R2430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-7) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ７５０－１１００（０ｄｅｇ）ＡＶＥ is less than 2%

[0011] According to the present invention, it is possible to provide an optical filter that suppresses ripples in the visible light region even at high angles of incidence, maintains high transmittance of visible light, and has excellent near-infrared and near-ultraviolet light blocking properties, particularly excellent ultraviolet light blocking properties with a wavelength of around 400 nm, and an imaging device equipped with the optical filter.

[0012] FIG. 1 is a schematic cross-sectional view of an example of an optical filter according to this embodiment. FIG. 2 is a diagram showing the spectral transmittance curve of phosphate glass. FIG. 3 is a diagram showing the spectral transmittance curve of the optical filter of Example 1-1. FIG. 4 is a diagram showing the spectral reflectance curve (A-side) of the optical filter of Example 1-1. FIG. 5 is a diagram showing the spectral reflectance curve (B-side) of the optical filter of Example 1-1. FIG. 6 is a diagram showing the spectral transmittance curve of the optical filter of Example 1-7. FIG. 7 is a diagram showing the spectral reflectance curve (A-side) of the optical filter of Example 1-7. FIG. 8 is a diagram showing the spectral reflectance curve (B-side) of the optical filter of Example 1-7. FIG. 9 is a diagram showing the spectral transmittance curve of the optical filter of Example 1-8. FIG. 10 is a diagram showing the spectral reflectance curve (A-side) of the optical filter of Example 1-8. FIG. 11 is a diagram showing the spectral reflectance curve (B-side) of the optical filter of Example 1-8.

[0013] Hereinafter, embodiments of the present invention will be described. In this specification, a near-infrared absorbing dye may be abbreviated as "IR dye" and an ultraviolet absorbing dye may be abbreviated as "UV dye". In this specification, a compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. A dye comprising compound (I) is also referred to as dye (I), and the same applies to other dyes. Furthermore, a group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

[0014] In this specification, internal transmittance is the transmittance obtained by subtracting the influence of interfacial reflection from the measured transmittance, as expressed by the formula {measured transmittance (incident angle 0 degrees) / (100-reflectance (incident angle 5 degrees))} x 100. In this specification, absorbance is converted from the (internal) transmittance using the formula -log10((internal) transmittance / 100). In this specification, the transmittance of a substrate and the spectrum of the transmittance of a resin film, including those in which a dye is contained in the resin, are all "internal transmittance" even when they are referred to as "transmittance." On the other hand, the transmittance of an optical filter having a dielectric multilayer film is the measured transmittance.

[0015] In this specification, a transmittance of, for example, 90% or more in a specific wavelength range means that the transmittance is not below 90% across the entire wavelength range, i.e., the minimum transmittance is 90% or more across that wavelength range. Similarly, a transmittance of, for example, 1% or less in a specific wavelength range means that the transmittance is not more than 1% across the entire wavelength range, i.e., the maximum transmittance is 1% or less across that wavelength range. The same applies to internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic mean of the transmittance and internal transmittance per 1 nm in that wavelength range. Spectral characteristics can be measured using a UV-Vis-NIR spectrophotometer. In this specification, the symbol "to" indicating a numerical range includes the upper and lower limits.

[0016] <Optical Filter> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "the present filter") comprises a substrate, an antireflection layer 1 made of a dielectric multilayer film laminated as an outermost layer on one main surface of the substrate, and an antireflection layer 2 made of a dielectric multilayer film laminated as an outermost layer on the other main surface of the substrate. The substrate comprises a near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass. The resin film contains a resin, a UV dye having a maximum absorption wavelength in the resin between 350 and 410 nm, and an IR dye having a maximum absorption wavelength in the resin between 700 and 850 nm. In the present invention, the dielectric multilayer film is an antireflection layer and therefore has low reflection characteristics, and the light-blocking properties of the optical filter are essentially ensured by the absorption characteristics of the near-infrared absorbing glass, the IR dye, and the UV dye. Because the absorption characteristics are not affected by the angle of incidence of light, the optical filter as a whole can achieve excellent transmittance in the visible light region and excellent blocking properties in the near-infrared and near-ultraviolet light regions while suppressing ripple in the visible light region.

[0017] An example of the configuration of the present filter will be described with reference to the drawings: Fig. 1 is a cross-sectional view schematically showing an example of an optical filter according to an embodiment.

[0018] 1 is an example in which a dielectric multilayer film 20A is provided on one main surface side of a substrate 10 having a near-infrared absorbing glass 11 and a resin film 12, and a dielectric multilayer film 20B is provided on the other main surface side. Note that "having a specific layer on the main surface side of the substrate" is not limited to the case in which the layer is provided in contact with the main surface of the substrate, but also includes the case in which another functional layer is provided between the substrate and the layer.

[0019] The optical filter according to this embodiment satisfies all of the following spectral characteristics (i-1) to (i-7): (i-1) The average transmittance T ３５０－３９０（０ｄｅｇ）ＡＶＥ (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is ４００（０ｄｅｇ） (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is 3% or less. ４００（０ｄｅｇ） and transmittance T at a wavelength of 430 nm ４３０（０ｄｅｇ） T satisfies the following relationship ４３０（０ｄｅｇ） -T４００（０ｄｅｇ） ≧78% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ４３０－６００（０ｄｅｇ）ＡＶＥ (i-5) When the antireflection layer 1 side is the incident direction, the absolute value of the difference between the average reflectance R1430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R1430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-6) When the antireflection layer 2 side is the incident direction, the absolute value of the difference between the average reflectance R2430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R2430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-7) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ７５０－１１００（０ｄｅｇ）ＡＶＥ is less than 2%

[0020] This filter, which satisfies all of the spectral characteristics (i-1) to (i-7), has excellent light-blocking properties in the near-ultraviolet region, as shown in characteristics (i-1) to (i-2), and can block light over a wide range up to around 400 nm, as shown in characteristic (i-2). It also has excellent visible light transmittance, as shown in characteristic (i-4), and excellent near-infrared light blocking properties, as shown in characteristic (i-7). Furthermore, as shown in characteristic (i-3), the transmittance changes sharply from the near-ultraviolet region to the visible light region. Furthermore, as shown in characteristics (i-5) to (i-6), the change in reflection characteristics is small at high angles of incidence in any direction of the optical filter's main surface, and ripples in the visible light region are suppressed.

[0021] In order to satisfy all of the spectral characteristics (i-1) to (i-7), it is preferable to use, for example, a dielectric multilayer film with suppressed reflection characteristics, to use phosphate glass or fluorophosphate glass as the near-infrared absorbing glass, and to use, as the UV dye, a merocyanine compound having a maximum absorption wavelength in the wavelength range of 370 to 410 nm and a zeromethine compound having a maximum absorption wavelength in the wavelength range of 350 to 380 nm, which will be described later.

[0022] Average transmittance T of characteristic (i-1)３５０－３９０（０ｄｅｇ）ＡＶＥ is 1% or less, preferably 0.8% or less, and more preferably 0.5% or less.

[0023] Transmittance T of characteristic (i-2) ４００（０ｄｅｇ） is 3% or less, preferably 2.5% or less, and more preferably 2% or less.

[0024] T of characteristic (i-3) ４３０（０ｄｅｇ） -T ４００（０ｄｅｇ） is 78% or more, preferably 79% or more, and more preferably 79.5% or more.

[0025] Average transmittance T of characteristic (i-4) ４３０－６００（０ｄｅｇ）ＡＶＥ is 80% or more, preferably 81% or more, and more preferably 82% or more.

[0026] In the characteristic (i-5), the absolute value of the difference between the average reflectance R1430-600 (5 deg) AVE and the average reflectance R1430-600 (50 deg) AVE is 4% or less, preferably 3.5% or less, and more preferably 3% or less.

[0027] In the characteristic (i-6), the absolute value of the difference between the average reflectance R2430-600 (5 deg) AVE and the average reflectance R2430-600 (50 deg) AVE is 4% or less, preferably 3.5% or less, and more preferably 3% or less.

[0028] Average transmittance T in characteristic (i-7) ７５０－１１００（０ｄｅｇ）ＡＶＥ is 2% or less, preferably 1.5% or less, and more preferably 1% or less.

[0029] The optical filter according to this embodiment preferably further satisfies the following spectral characteristic (i-8): (i-8) In the spectral transmittance curve at an incident angle of 50 degrees, the transmittance T ４００（５０ｄｅｇ） This makes it possible to obtain an optical filter that is excellent in blocking light around 400 nm even at a high incident angle. ４００（５０ｄｅｇ） is more preferably 2.5% or less, and further preferably 2% or less.

[0030] The optical filter according to this embodiment preferably further satisfies the following spectral characteristic (i-9): (i-9) An average transmittance T ３５０－３９０（５０ｄｅｇ）ＡＶＥ This makes it possible to obtain an optical filter that is excellent in blocking light in the near-ultraviolet region with a wavelength of 350 to 390 nm. ３５０－３９０（５０ｄｅｇ）ＡＶＥ is more preferably 1.3% or less, and further preferably 1% or less.

[0031] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (i-10) and (i-11): (i-10) In the spectral transmittance curve at an incident angle of 0 degrees, the minimum wavelength T at which the transmittance becomes 50% in the wavelength range of 350 to 430 nm （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 1 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R1 (5 deg) UV50 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０ -R1 (5deg) UV50>10nm (i-11) Above T （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 2 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R2 (5 deg) UV50 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０ -R2 (5 deg) UV50>10 nm This provides an optical filter with a large difference between the transmittance and reflectance at the cut edge, that is, with small reflection characteristics and light blocking properties ensured by absorption characteristics. （０ｄｅｇ）ＵＶ５０ -R1 (5 deg) UV50>11 nm, more preferably T （０ｄｅｇ）ＵＶ５０ -R1 (5 deg) UV50>12 nm. In the characteristic (i-11), more preferably T （０ｄｅｇ）ＵＶ５０ -R2 (5 deg) UV50>11 nm, more preferably T （０ｄｅｇ）ＵＶ５０ -R2 (5 deg) UV50>12 nm.

[0032] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (i-12) to (i-14): （０ｄｅｇ）ＵＶ５０(i-13) In the spectral transmittance curve at an incident angle of 50 degrees, the minimum wavelength T at which the transmittance is 50% in the wavelength range of 350 to 430 nm is （５０ｄｅｇ）ＵＶ５０ (i-14) The wavelength of T is in the range of 400 to 430 nm. （０ｄｅｇ）ＵＶ５０ and the T （５０ｄｅｇ）ＵＶ５０ The absolute value of the difference between the above is 4 nm or less. By satisfying the characteristics (i-12) and (i-13), the region (cut edge) where the near-ultraviolet light blocking region and the visible light transmitting region switch is in the same region even at a high incident angle, and by satisfying the characteristic (i-14), an optical filter can be obtained in which the fluctuation amount of the cut edge is small.

[0033] In the characteristic (i-12), the wavelength T （０ｄｅｇ）ＵＶ５０ is more preferably 405 to 430 nm, and further preferably 410 to 425 nm. （５０ｄｅｇ）ＵＶ５０ is more preferably 405 to 430 nm, and even more preferably 410 to 425 nm. （０ｄｅｇ）ＵＶ５０ and T （５０ｄｅｇ）ＵＶ５０ The absolute value of the difference is more preferably 3 nm or less, and further preferably 2 nm or less.

[0034] The optical filter according to this embodiment preferably further satisfies the following spectral characteristic (i-15): (i-15) Average transmittance T for wavelengths from 430 to 600 nm in the spectral transmittance curve at an incident angle of 0 degrees ４３０－６００（０ｄｅｇ）ＡＶＥ and the average transmittance T of the wavelength of 430 to 600 nm in the spectral transmittance curve at an incident angle of 50 degrees. ４３０－６００（５０ｄｅｇ）ＡＶＥ T satisfies the following relationship ４３０－６００（０ｄｅｇ）ＡＶＥ -T ４３０－６００（５０ｄｅｇ）ＡＶＥ ≦4.5% This allows for an optical filter that does not use a reflective layer, resulting in small ripples in the visible light region, and in which the visible light transmittance is less likely to decrease even at high angles of incidence. ４３０－６００（０ｄｅｇ）ＡＶＥ -T ４３０－６００（５０ｄｅｇ）ＡＶＥ is more preferably 4.3% or less, and even more preferably 4% or less.

[0035] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (i-16) and (i-17): (i-16) When the antireflection layer 1 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R1750-1100 (5 deg) AVE for wavelengths of 750 to 1100 nm is 15% or less; (i-17) When the antireflection layer 2 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R2750-1100 (5 deg) AVE for wavelengths of 750 to 1100 nm is 15% or less. This allows for an optical filter with low reflection characteristics in the near-infrared region to be obtained. The average reflectance R1750-1100 (5 deg) AVE is more preferably 13% or less, and even more preferably 12% or less. The average reflectance R2750-1100 (5 deg) AVE is more preferably 13% or less, and even more preferably 12% or less.

[0036] The optical filter according to this embodiment preferably further satisfies the following spectral characteristics (i-18) to (i-20): (i-18) A minimum transmittance T of 430 to 600 nm in a spectral transmittance curve at an incident angle of 0 degrees. ４３０－６００（０ｄｅｇ）ＭＩＮ (i-19) In the spectral transmittance curve at an incident angle of 0 degrees, the maximum transmittance T ４３０－６００（０ｄｅｇ）ＭＡＸ (i-20) In the spectral transmittance curve at an incident angle of 0 degrees, the maximum transmittance T ７５０－１１００（０ｄｅｇ）ＭＡＸ By satisfying the characteristic (i-18) and the characteristic (i-19), an optical filter having excellent visible light transmittance can be obtained, and by satisfying the characteristic (i-20), an optical filter having excellent near-infrared shielding properties can be obtained.

[0037] In the characteristic (i-18), T ４３０－６００（０ｄｅｇ）ＭＩＮ is more preferably 62% or more, and further preferably 64% or more. ４３０－６００（０ｄｅｇ）ＭＡＸ is more preferably 91% or more, and even more preferably 93% or more. ７５０－１１００（０ｄｅｇ）ＭＡＸ is more preferably 2.5% or less, and even more preferably 2% or less.

[0038] <Substrate> In the optical filter according to this embodiment, the substrate has a near-infrared absorbing glass and a resin film. The resin film is laminated on at least one main surface of the near-infrared absorbing glass, and contains a resin, a UV dye having a maximum absorption wavelength in the resin between 350 and 410 nm, and an IR dye having a maximum absorption wavelength in the resin between 700 and 850 nm. In this embodiment, the substrate has both the absorption ability of the near-infrared absorbing glass and the absorption ability of the resin film containing the UV dye and the IR dye.

[0039] <Near-infrared absorbing glass> The near-infrared absorbing glass preferably satisfies both of the following spectral characteristics (ii-1) and (ii-2): (ii-1) Average internal transmittance T ４５０－６００ＡＶＥ (ii-2) Average internal transmittance T of wavelength 750 to 1100 nm ７５０－１１００ＡＶＥ That is, it is preferable that the near-infrared absorbing glass has both high transmittance in the visible light region and light blocking properties in the wide near-infrared region from 750 to 1100 nm. ４５０－６００ＡＶＥ is more preferably 81% or more, and further preferably 82% or more. ７５０－１１００ＡＶＥ is more preferably 4% or less, and further preferably 3% or less.

[0040] The near-infrared absorbing glass is not limited as long as it can provide the above-mentioned spectral characteristics, and examples thereof include absorption-type glasses containing copper ions in fluorophosphate glass and phosphate glass. Among these, phosphate glass is preferred from the viewpoint of easily providing the above-mentioned spectral characteristics. Note that "phosphate glass" is a glass in which part of the skeleton of the glass is SiO ２ Also included is a silicophosphate glass consisting of

[0041] For example, it is preferable that the phosphate glass contains the following glass-constituting components. The content ratio of each of the following glass-constituting components is expressed as a mass percentage based on the oxide. ２ O ５ 40-80% Al ２ O ３ 0.5 to 20% ΣR ２ O (However, R ２ O is Li ２ O, Na２ O.K. ２ O, Rb ２ O, and Cs ２ one or more components selected from O, ΣR ２ O is R ２ ΣR'O (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO, and ΣR'O is the total amount of R'O) 0 to 40% CuO 0.5 to 40%

[0042] P ２ O ５ is the main component that forms glass and is a component that enhances the near-infrared ray blocking properties. ２ O ５ If the content is 40% or more, the effect is sufficiently obtained, and if it is 80% or less, problems such as glass instability and reduced weather resistance are unlikely to occur. Therefore, the content is preferably 40 to 80%, more preferably 45 to 78%, even more preferably 50 to 77%, still more preferably 55 to 76%, and most preferably 60 to 75%.

[0043] Al ２ O ３ is the main component that forms glass, and is a component that increases the strength and weather resistance of glass. ２ O ３ If the content is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur. Therefore, the content is preferably 0.5 to 20%, more preferably 1.0 to 20%, even more preferably 2.0 to 18%, still more preferably 3.0 to 17%, particularly preferably 4.0 to 16%, and most preferably 5.0 to 15.5%.

[0044] R ２ O (However, R ２ O is Li ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２O) are components for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. ２ The total amount of O (ΣR ２ If O) is 0.5% or more, the effect is sufficiently obtained, and if it is 20% or less, the glass is less likely to become unstable, which is preferable. Therefore, it is preferably 0.5 to 20%, more preferably 1.0 to 19%, even more preferably 1.5 to 18%, still more preferably 2.0 to 17%, particularly preferably 2.5 to 16%, and most preferably 3 to 15.5%.

[0045] Li ２ O is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, etc. ２ The content of O is preferably 0 to 15%. ２ An O content of 15% or less is preferred because problems such as glass instability and reduced near-infrared blocking properties are unlikely to occur, and the O content is more preferably 0 to 8%, even more preferably 0 to 7%, still more preferably 0 to 6%, and most preferably 0 to 5%.

[0046] Na ２ O is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. ２ The content of O is preferably 0 to 15%. ２ If the O content is 15% or less, the glass is less likely to become unstable, which is preferable, more preferably 0.5 to 14%, even more preferably 1 to 13%, still more preferably 2 to 13%, and most preferably 3 to 13%.

[0047] K ２ O is a component that has the effect of lowering the melting temperature of the glass and the liquidus temperature of the glass. ２ The O content is preferably 0 to 20%. ２If the O content is 20% or less, the glass is less likely to become unstable, which is preferable, and the O content is more preferably 0.5 to 19%, even more preferably 1 to 18%, still more preferably 2 to 17%, and most preferably 3 to 16%.

[0048] Rb ２ O is a component that has the effects of lowering the melting temperature of the glass and lowering the liquidus temperature of the glass. ２ The content of O is preferably 0 to 15%. ２ If the O content is 15% or less, the glass is less likely to become unstable, which is preferable, more preferably 0.5 to 14%, even more preferably 1 to 13%, still more preferably 2 to 13%, and most preferably 3 to 13%.

[0049] Cs ２ O is a component that has the effect of lowering the melting temperature of the glass and the liquidus temperature of the glass. ２ The content of O is preferably 0 to 15%. ２ If the O content is 15% or less, the glass is less likely to become unstable, which is preferable, more preferably 0.5 to 14%, even more preferably 1 to 13%, still more preferably 2 to 13%, and most preferably 3 to 13%.

[0050] In addition, the above R ２ The alkali metal components represented by O produce a mixed alkali effect in the glass by adding two or more of each component at the same time, and R ＋ The mobility of ions is reduced, so that when the glass comes into contact with water, the H ＋ Ions and R in glass ＋ The phosphate glass of this embodiment contains Li, which inhibits the hydration reaction caused by the ion exchange of ions, thereby improving the weather resistance of the glass. ２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ In this case, it is preferable that the compound contains two or more components selected from R ２ O (However, R ２ O is Li２ O, Na ２ O.K. ２ O, Rb ２ O, and Cs ２ O) total amount (ΣR ２ O) is preferably more than 7% and 18% or less. ２ If the total amount of O exceeds 7%, the effect can be sufficiently obtained, and if it is 18% or less, problems such as instability of the glass, deterioration of the near-infrared cutoff property, and deterioration of the strength of the glass are unlikely to occur, which is preferable. ２ O is preferably more than 7% and not more than 18%, more preferably 7.5 to 17%, even more preferably 8 to 16%, still more preferably 8.5 to 15%, and most preferably 9 to 14%.

[0051] R'O (where R'O is one or more components selected from CaO, MgO, BaO, SrO, and ZnO) is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and increases the strength of the glass. The total amount of R'O (ΣR'O) is preferably 0 to 40%. A total amount of R'O of 40% or less is preferred because problems such as glass instability, reduced near-infrared cutoff ability, and reduced strength are less likely to occur. The amount is more preferably 0 to 35%, and even more preferably 0 to 30%. The amount is even more preferably 0 to 25%, particularly preferably 0 to 20%, and most preferably 0 to 15%.

[0052] CaO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The CaO content is preferably 0 to 10%. A CaO content of 10% or less is preferred because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The CaO content is more preferably 0 to 8%, even more preferably 0 to 6%, even more preferably 0 to 5%, and most preferably 0 to 4%.

[0053] MgO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and increases the strength of glass. The MgO content is preferably 0 to 15%. An MgO content of 15% or less is preferred because it is less likely to cause problems such as glass instability and reduced near-infrared blocking properties. The MgO content is more preferably 0 to 13%, even more preferably 0 to 10%, even more preferably 0 to 9%, and most preferably 0 to 8%.

[0054] BaO is a component that lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, stabilizes the glass, and so on. The BaO content is preferably 0 to 40%. A BaO content of 40% or less is preferred because problems such as glass instability and reduced near-infrared cutoff are less likely to occur. The BaO content is more preferably 0 to 30%, even more preferably 0 to 20%, even more preferably 0 to 10%, and most preferably 0 to 5%.

[0055] SrO is a component that lowers the melting temperature of glass, lowers the liquidus temperature of glass, stabilizes glass, and so on. The SrO content is preferably 0 to 10%. If the SrO content is 10% or less, problems such as glass instability and reduced near-infrared cutoff properties are less likely to occur, which is preferable. The SrO content is more preferably 0 to 8%, even more preferably 0 to 7%, and most preferably 0 to 6%.

[0056] ZnO has the effect of lowering the melting temperature of glass, lowering the liquidus temperature of glass, etc. The ZnO content is preferably 0 to 15%. A ZnO content of 15% or less is preferable because it is less likely to cause problems such as glass instability, deterioration in glass meltability, and reduced near-infrared cutoff properties. The ZnO content is more preferably 0 to 13%, even more preferably 0 to 10%, even more preferably 0 to 9%, and most preferably 0 to 8%.

[0057] CuO is a component for enhancing near-infrared blocking properties. The CuO content is preferably 0.5 to 40%. If the CuO content is 0.5% or more, the effect is sufficiently obtained, and if it is 40% or less, problems such as the generation of devitrification inclusions in the glass and a decrease in transmittance of light in the visible region are less likely to occur, which is preferable. The CuO content is more preferably 1.0 to 35%, even more preferably 1.5 to 30%, even more preferably 2.0 to 25%, and most preferably 2.5 to 20%.

[0058] F may be contained in a range of 10% or less to improve weather resistance. If the F content is 10% or less, problems such as a decrease in near-infrared blocking ability and the generation of devitrification inclusions in the glass are unlikely to occur, which is preferable. The F content is more preferably 9% or less, even more preferably 8% or less, still more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0059] B ２ O ３ may be contained in an amount of 10% or less to stabilize the glass. ２ O ３ It is preferable that the content of is 10% or less, since problems such as deterioration of the weather resistance of the glass and reduction in the near-infrared cutoff property are unlikely to occur. It is more preferably 9% or less, even more preferably 8% or less, still more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less.

[0060] In this embodiment, SiO ２ , GeO ２ , ZrO ２ , SnO ２ , TiO ２ , CeO ２ , MoO ３ , W.O. ３ , Y ２ O ３ , La ２ O ３ , Gd ２ O ３ , Yb ２ O ３ , Nb ２ O ５may be contained in a range of 5% or less to improve the weather resistance of the phosphate glass. If the content of these components is 5% or less, problems such as the generation of devitrification inclusions in the glass and a decrease in the near-infrared cutoff property are unlikely to occur, which is preferable. The content is preferably 4% or less, more preferably 3% or less, even more preferably 2% or less, and even more preferably 1% or less.

[0061] Fe ２ O ３ , Cr ２ O ３ , Bi ２ O ３ , NiO, V ２ O ５ , MnO ２ and CoO are components that, when present in phosphate glass, reduce the transmittance of light in the visible region. Therefore, it is preferable that these components are not substantially contained in the glass. In the present invention, "substantially not containing a specific component" means that the component is not intentionally added, and does not exclude the inclusion of a component to the extent that it is unavoidably mixed in from raw materials, etc., and does not affect the desired properties.

[0062] The near-infrared absorbing glass preferably has a thickness of 0.5 mm or less, more preferably 0.3 mm or less, from the viewpoint of reducing the height of the camera module, and preferably has a thickness of 0.15 mm or more, from the viewpoint of element strength.

[0063] Phosphate glass can be produced, for example, as follows: First, raw materials are weighed and mixed so as to achieve the above-mentioned composition range (mixing step). This raw material mixture is placed in a platinum crucible and heated and melted at a temperature of 700 to 1400°C in an electric furnace (melting step). After thorough stirring and clarification, the mixture is poured into a mold, cut, polished, and formed into a plate of the specified thickness (forming step).

[0064] In the melting step of the above manufacturing method, the highest temperature of the glass during melting is preferably 1400°C or lower. If the highest temperature of the glass during melting exceeds this temperature, the transmittance characteristics may deteriorate. The temperature is more preferably 1350°C or lower, even more preferably 1300°C or lower, and even more preferably 1250°C or lower.

[0065] Furthermore, if the temperature in the melting step is too low, problems such as devitrification occurring during melting and a long time required for melting through may occur, so the temperature is preferably 700°C or higher, more preferably 800°C or higher.

[0066] <UV Dye> The UV dye is not limited as long as it is a compound having a maximum absorption wavelength in the range of 350 to 410 nm in the resin, but it preferably contains at least one of a merocyanine compound having a maximum absorption wavelength in the range of 370 to 410 nm in the resin and a zeromethine compound having a maximum absorption wavelength in the range of 350 to 380 nm in the resin, and more preferably contains both from the viewpoint of efficiently blocking a wide near-ultraviolet light range. Note that the resin is the resin used in the resin film in the optical filter according to this embodiment.

[0067] (Merocyanine Compound) The merocyanine compound is preferably a compound represented by the following formula (M). The compound represented by the following formula (M) is preferred because the dye compound itself has excellent light resistance and is resistant to photodegradation. It is also preferred because it does not affect the light resistance of the IR dye even when used in combination with the IR dye.

[0068]

[0069] [The symbols in formula (M) are defined as follows: R ２１ represents a monovalent hydrocarbon group having 1 to 16 carbon atoms which may have a substituent. ２２ ~R ２５ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. ２０ is R ２６ and R ２７ represents a methylene group or an oxygen atom substituted with X ２０ represents any one of the divalent groups represented by the following formulas (X1) to (X5).

[0070]

[0071] R ２８ and R ２９ each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, R３０ ~R ３９ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent.

[0072] In formula (M), R ２１ represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, which may have a substituent. The substituent is preferably an alkoxy group, an acyl group, an acyloxy group, a cyano group, a dialkylamino group, or a chlorine atom. The alkoxy group, acyl group, acyloxy group, and dialkylamino group preferably have 1 to 6 carbon atoms.

[0073] Preferred R ２１ is an alkyl group having 1 to 6 carbon atoms in which some of the hydrogen atoms may be substituted with a cycloalkyl group or a phenyl group. ２１ is an alkyl group having 1 to 6 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group.

[0074] R ２２ ~R ２５ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. The alkyl group and alkoxy group preferably have 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms.

[0075] R ２２ and R ２３ At least one of R is preferably an alkyl group, and more preferably both are alkyl groups. ２２ and R ２３ When R is not an alkyl group, a hydrogen atom is more preferred. ２２ and R ２３ is particularly preferably an alkyl group having 1 to 6 carbon atoms.

[0076] R ２４ and R ２５ At least one of R is preferably a hydrogen atom, and more preferably both are hydrogen atoms. ２４ and R ２５ When is not a hydrogen atom, it is preferably an alkyl group having 1 to 6 carbon atoms.

[0077] Y２０ is R ２６ and R ２７ represents a methylene group or an oxygen atom substituted with R ２６ and R ２７ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.

[0078] X ２０ represents any one of the divalent groups represented by the above formulas (X1) to (X5).

[0079] R ２８ and R ２９ each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, R ３０ ~R ３９ R each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent. ２８ ~R ３９ The substituents of R ２１ The same substituents as those in the group R are mentioned, and the preferred embodiments are also the same. ２８ ~R ３９ is a hydrocarbon group having no substituents, R ２１ The same aspects as above can be mentioned.

[0080] Preferred R ２８ and R ２９ are all alkyl groups having 1 to 6 carbon atoms in which some of the hydrogen atoms may be substituted with cycloalkyl groups or phenyl groups. Particularly preferred R ２８ and R ２９ are all alkyl groups having 1 to 6 carbon atoms, and specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group.

[0081] In formula (X2), R ３０ and R ３１ are more preferably alkyl groups having 1 to 6 carbon atoms, and it is particularly preferred that they are the same alkyl groups.

[0082] In formula (X3), R ３２ and R ３５are preferably both hydrogen atoms or unsubstituted alkyl groups having 1 to 6 carbon atoms. ３３ and R ３４ are preferably all hydrogen atoms or all alkyl groups having 1 to 6 carbon atoms.

[0083] In formula (X4), two groups R bonded to the same carbon atom ３６ and R ３７ and R ３８ and R ３９ are preferably all hydrogen atoms or all alkyl groups having 1 to 6 carbon atoms.

[0084] The compound represented by formula (M) includes Y ２０ is an oxygen atom, and X ２０ is a group (X1), a group (X2) or a group (X5), and ２０ is an unsubstituted methylene group, and X ２０ is a group (X1), a group (X2) or a group (X5).

[0085] Specific examples of the compound (M) include the compounds shown in the table below.

[0086]

[0087] As the compound (M), the compounds (M-2), (M-8), (M-9), (M-13) and (M-20) are preferred in terms of their solubility in resins and appropriate maximum absorption wavelengths.

[0088] Compound (M) can be produced by a known method, for example, as described in Japanese Patent No. 6,504,176.

[0089] (Zeromethine Compound) The zeromethine compound is preferably a compound represented by the following formula (I). The compound represented by the following formula (I) is preferred because the dye compound itself has excellent light resistance and is resistant to photodegradation. It is also preferred because it does not affect the light resistance of the IR dye even when used in combination with the IR dye.

[0090]

[0091] [The symbols in formula (I) are defined as follows: X represents an oxygen atom, a sulfur atom, or N—R １４ , or C-R １５ R １６ (R １４ ~R １６ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. １ is an alkyl group having 1 to 6 carbon atoms which may have a substituent. ２ ~R ５ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, a nitro group, an amino group, or an amide group. A represents any of the divalent groups represented by the following formulas (A1) to (A4):

[0092]

[0093] In formulas (A1) to (A4), Y is an oxygen atom or a sulfur atom, and R ６ ~R １３ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent.

[0094] In compound (I), X is an oxygen atom, a sulfur atom, or N—R １４ , or C-R １５ R １６ It is. １４ ~R １６ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent, and examples of the substituent include an alkoxy group, an acyl group, an acyloxy group, a cyano group, a dialkylamino group, or a chlorine atom. １４ ~R １６ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent. X is an oxygen atom, a sulfur atom, or C—R １５ R １６ is preferred, and an oxygen atom or a sulfur atom is more preferred. That is, compound (I) is more preferably a compound represented by the following formula (I)'.

[0095]

[0096] (In formula (I)′, X′ is an oxygen atom or a sulfur atom, and R １ is an alkyl group having 1 to 6 carbon atoms which may have a substituent, and R ２ ~R ５ are each independently a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 10 carbon atoms which may have a substituent, a nitro group, an amino group, or an amide group, and A represents any of the divalent groups represented by the above formulas (A1) to (A4).

[0097] In compound (I) or compound (I)′, R １ R is an alkyl group having 1 to 6 carbon atoms which may have a substituent. Examples of the substituent which may have include an alkoxy group, an acyl group, an acyloxy group, a cyano group, a dialkylamino group, and a chlorine atom. １ is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and even more preferably a methyl group.

[0098] In compound (I) or compound (I)′, R ２ ~R ５ are each independently a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 10 carbon atoms which may have a substituent, a nitro group, an amino group, or an amido group. Examples of the substituent which may have include an alkoxy group, an acyl group, an acyloxy group, a cyano group, a dialkylamino group, or a chlorine atom. ２ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom, and more preferably a hydrogen atom. ３ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ４ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom, and more preferably a hydrogen atom. ５ is preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a halogen atom, more preferably a hydrogen atom.

[0099] In compound (I) or compound (I)′, A represents any one of the divalent groups represented by the above formulae (A1) to (A4), and is preferably a divalent group represented by formula (A1) or (A3).

[0100] In the divalent group represented by formula (A1), Y is an oxygen atom or a sulfur atom. When X in formula (I) or X' in formula (I)' is a sulfur atom, Y is preferably an oxygen atom. When Y is a sulfur atom, X is preferably an oxygen atom, N-R １４ , or C-R １５ R １６ is preferable, and an oxygen atom is more preferable, and X' is preferably an oxygen atom. Also, at least one of X or X' and Y is preferably an oxygen atom.

[0101] In the divalent groups represented by formulae (A1) to (A4), R ６ ~R １３ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or a phenyl group. Examples of the substituent which may have include an alkoxy group, an acyl group, an acyloxy group, a cyano group, a dialkylamino group, or a chlorine atom. ６ and R ７ are each independently preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, more preferably an alkyl group having 1 to 6 carbon atoms. ８ and R ９ are each independently preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, more preferably an alkyl group having 1 to 6 carbon atoms. １０ and R １１ are each independently preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a phenyl group, more preferably an alkyl group having 1 to 6 carbon atoms. １２ and R １３ are each independently preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom.

[0102] More specifically, compound (I) or compound (I)' includes compounds in which the atoms or groups bonded to each skeleton are shown in the following Table 2. In the table, i-Bu means an isobutyl group, t-Bu means a tertiary butyl group, and Ph means a phenyl group.

[0103]

[0104] Among the above, the compounds with the dye abbreviations I-1, I-2, I-3 and I-8 are particularly preferred.

[0105] The method for producing compound (I) or compound (I)′ is not particularly limited, but for example, 2-(methylthio)benzothiazole is reacted with methyl p-toluenesulfonate to obtain intermediate 1 represented by the following formula: In the formula, Ts represents a tosyl group.

[0106]

[0107] The compound (I) or compound (I)' can be obtained by reacting the intermediate 1 with a compound corresponding to the divalent group represented by formula (A1) to (A4) in the presence of a solvent. １ ~R ５ or a 2-(methylthio)benzoxazole or 2-(methylthio)indole derivative, etc., where the hydrogen atom corresponding to the formula (I) is substituted with a substituent, to obtain compound (I) or compound (I)' having the desired structure.

[0108] The content of the UV dye in the resin film is preferably in a range such that the product of the content of the UV dye in mass % and the thickness of the resin film is 20.0 (mass % μm) or less, more preferably 19.0 (mass % μm) or less, and particularly preferably 18.0 (mass % μm) or less. By setting the content of the UV dye within this range, deterioration of the resin properties can be prevented and good adhesion with the dielectric multilayer film and the near-infrared absorbing glass can be maintained. Furthermore, deterioration of heat resistance due to a decrease in the glass transition temperature of the resin can be suppressed. Furthermore, from the viewpoint of achieving the desired spectral characteristics, this product is preferably 3.0 (mass % μm) or more, more preferably 5.0 (mass % μm) or more. Incidentally, even when multiple compounds are used as the UV dye, it is preferable that the product of the total content of the multiple UV dyes and the thickness of the resin film satisfy the above range.

[0109] From the viewpoint of ensuring that the product of the content of the UV dye and the thickness of the resin film satisfies the above range, the content of the UV dye in the resin film is preferably 3.0 parts by mass or more, more preferably 5.0 parts by mass or more, and is preferably 15.0 parts by mass or less, more preferably 14.0 parts by mass or less, relative to 100 parts by mass of the resin. Note that even when multiple compounds are used as the UV dye, it is preferable that the total content of the multiple UV dyes satisfies the above range.

[0110] <IR Dye> The IR dye is not limited as long as it has a maximum absorption wavelength in the range of 700 to 850 nm in the resin, but is preferably at least one selected from the group consisting of squarylium dyes, cyanine dyes, phthalocyanine dyes, naphthalocyanine dyes, dithiol metal complex dyes, azo dyes, polymethine dyes, phthalide dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, croconium dyes, tetradehydrocoline dyes, triphenylmethane dyes, aminium dyes, and diimmonium dyes, and more preferably at least one dye selected from the group consisting of squarylium dyes, phthalocyanine dyes, and cyanine dyes. Among these IR dyes, squarylium dyes and cyanine dyes are preferred from the viewpoint of spectral properties, and phthalocyanine dyes are preferred from the viewpoint of durability.

[0111] The content of the IR dye in the resin film is preferably 3.0 parts by mass or more, more preferably 5.0 parts by mass or more, and is preferably 25.0 parts by mass or less, more preferably 20.0 parts by mass or less, per 100 parts by mass of the transparent resin.

[0112] <Resin> The resin contained in the resin film is not particularly limited as long as it is a transparent resin that transmits visible light with a wavelength of 400 to 700 nm.

[0113] Examples of transparent resins include polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins. These transparent resins may be used alone or in combination of two or more. Among these, polyimide resins are preferred from the viewpoints of excellent visible light transmittance, a high glass transition temperature of the resin, and resistance to thermal degradation of the dye.

[0114] The optical filter may have one resin film layer or two or more resin films. When the optical filter has two or more resin films, the resin films may have the same or different configurations.

[0115] The thickness of the resin film is preferably 5 μm or less, more preferably 3 μm or less, from the viewpoint of obtaining a uniform film with a small film thickness distribution. Furthermore, from the viewpoint of obtaining desired spectral characteristics, the thickness of the resin film is preferably 0.5 μm or more, more preferably 1 μm or more. When the optical filter according to this embodiment includes two or more resin film layers, it is preferable that the thickness of each resin film satisfies the above range.

[0116] <Dielectric multilayer film> In this filter, a dielectric multilayer film is laminated as the outermost layer on both main surfaces of the substrate. Each dielectric multilayer film is designed as an anti-reflection layer with low reflectance in the ultraviolet, visible, and near-infrared regions.

[0117] The anti-reflection layer is composed of a dielectric multilayer film formed by stacking two or more of a low refractive index dielectric film (low refractive index film), a medium refractive index dielectric film (medium refractive index film), and a high refractive index dielectric film (high refractive index film), for example.

[0118] In optical filters, ripples in visible light occur due to interference caused by reflected light at the interfaces of the dielectric multilayer films stacked as reflective layers. Therefore, by stacking the dielectric multilayer films as antireflection layers as described above, an optical filter in which ripples in visible light are suppressed can be obtained.

[0119] In this specification, the term "antireflection layer" refers to a layer that does not have a wavelength band of 100 nm or more in width where the reflectance is 90% or more in a spectral reflectance curve for wavelengths of 750 to 1200 nm and an incident angle of 5 degrees, and the term "reflective layer" refers to a layer that has a wavelength band of 100 nm or more in width where the reflectance is 90% or more in a spectral reflectance curve for wavelengths of 750 to 1200 nm and an incident angle of 5 degrees, or a layer designed so that the absolute value of the difference between the average reflectance for wavelengths of 430 to 600 nm in the spectral reflectance curve for an incident angle of 5 degrees on the surface on which the antireflection layer of the optical filter is laminated and the average reflectance for wavelengths of 430 to 600 nm in the spectral reflectance curve for an incident angle of 50 degrees is 4% or less.

[0120] The high refractive index film preferably has a refractive index of 1.6 or more, more preferably 2.2 to 2.5. Examples of the material for the high refractive index film include Ta. ２ O ５ , TiO ２ , TiO, Nb ２ O ５ Other commercially available products include OS50 (Ti) manufactured by Canon Optron Co., Ltd. ３ O ５ ), OS10 (Ti ４ O ７ ), OA500 (Ta ２ O ５ and ZrO ２ a mixture of OA600 (Ta ２ O ５ and TiO ２ Among these, TiO is preferred in terms of film-forming property, reproducibility in refractive index, stability, etc. ２ is preferred.

[0121] The refractive index of the medium refractive index film is preferably 1.6 or more and less than 2.2. Examples of the material for the medium refractive index film include ZrO. ２ , Nb ２ O ５ , Al ２ O ３ , HfO ２ and OM-4 and OM-6 (Al) sold by Canon Optron. ２ O ３ and ZrO ２ Among these, Al is preferred in terms of film-forming properties, reproducibility in refractive index, stability, etc. ２ O ３ Al-based compounds ２ O ３ and ZrO ２ A mixture of is preferred.

[0122] The low refractive index film preferably has a refractive index of less than 1.6, more preferably 1.45 or more and less than 1.55. Examples of the material for the low refractive index film include SiO ２ , SiO ｘ N ｙ、 MgF ２ Other commercially available products include S4F and S5F (SiO ２ and Al ２ O ３ Among these, SiO is preferred from the viewpoints of reproducibility, stability, economy, etc. in film formation. ２ is preferred.

[0123] In order to obtain a dielectric multilayer film with suppressed reflection characteristics, it is possible to combine several types of dielectric films with different spectral characteristics when transmitting and selecting a desired wavelength band.

[0124] The antireflection layer preferably has a total number of laminated layers of the dielectric multilayer film of 20 or less, more preferably 18 or less, even more preferably 15 or less, and preferably 5 or more. To suppress reflection in the visible wavelength range even when the angle of incidence changes, a film with low reflectivity across the entire wavelength range is preferred, rather than a film that reflects only specific wavelengths. The overall thickness of the antireflection layer is preferably 1 μm or less, more preferably 0.9 μm or less, and preferably 0.2 μm or more. It is preferable that both antireflection layer 1 and antireflection layer 2 satisfy the above-mentioned number of laminated layers and film thickness.

[0125] The dielectric multilayer film can be formed by vacuum film-forming processes such as CVD, sputtering, and vacuum deposition, or wet film-forming processes such as spraying and dipping.

[0126] The antireflection layer may be a single layer (a group of dielectric multilayer films) that provides predetermined optical properties, or two layers that provide predetermined optical properties. When there are two or more antireflection layers, the antireflection layers may have the same or different configurations.

[0127] <Other Functional Layers> The optical filter according to this embodiment may further include functional layers having other functions as other components, provided that the effects of the present invention are not impaired. Examples of other functional layers include functional layers that provide absorption using inorganic fine particles that control the transmission and absorption of light in a specific wavelength range. Examples of the inorganic fine particles include indium tin oxide (ITO), antimony-doped tin oxide (ATO), cesium tungstate, and lanthanum boride. ITO fine particles and cesium tungstate fine particles have high visible light transmittance and light absorption over a wide range of infrared wavelengths exceeding 1200 nm, and therefore can be used when such infrared light blocking is required.

[0128] The optical filter according to the present embodiment, when used in an imaging device such as a digital still camera, can provide an imaging device with excellent color reproducibility. That is, the imaging device according to the present embodiment preferably includes the optical filter, and more specifically, includes a solid-state imaging element, an imaging lens, and the optical filter. The optical filter can be used, for example, by being disposed between the imaging lens and the solid-state imaging element, or by being directly attached to the solid-state imaging element, imaging lens, etc. of the imaging device via an adhesive layer.

[0129] <Method for manufacturing optical filter> The resin film in the optical filter according to this embodiment can be formed by dissolving or dispersing a resin or its raw material components, a UV dye, an IR dye, and other components blended as needed in a solvent to prepare a coating liquid, applying the coating liquid to a support, drying it, and further curing it as needed. If the support in this case is the near-infrared absorbing glass used in the optical filter according to this embodiment, the substrate can be manufactured as is. If the support is a peelable support used only when forming the resin film, the obtained resin film can be integrated with the near-infrared absorbing glass by thermocompression bonding or the like to manufacture the substrate.

[0130] The solvent in the coating solution may be any dispersion medium in which each component can be stably dispersed or dissolved. The coating solution may also contain a surfactant to prevent voids caused by minute bubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process.

[0131] The coating liquid can be applied by, for example, dip coating, cast coating, spin coating, etc. Curing is carried out by a curing treatment such as heat curing or photocuring.

[0132] The resin film can also be produced in a film form by extrusion molding. In this case, the resulting film-like resin film can be laminated on near-infrared absorbing glass and integrated by thermocompression bonding or the like to produce a substrate.

[0133] The optical filter according to the present embodiment is obtained by forming antireflection layers 1 and 2, each made of a dielectric multilayer film, on the outermost layers on both main surfaces of the obtained substrate. If desired, other functional layers may also be formed on the optical filter.

[0134] As described above, this specification discloses the following optical filter and imaging device. [1] An optical filter comprising a substrate, an antireflection layer 1 made of a dielectric multilayer film laminated as an outermost layer on one main surface of the substrate, and an antireflection layer 2 made of a dielectric multilayer film laminated as an outermost layer on the other main surface of the substrate, wherein the substrate has a near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass, and the resin film contains a resin, a UV dye having a maximum absorption wavelength in the resin at 350 to 410 nm, and an IR dye having a maximum absorption wavelength in the resin at 700 to 850 nm, and the optical filter satisfies all of the following spectral characteristics (i-1) to (i-7): (i-1) An average transmittance T ３５０－３９０（０ｄｅｇ）ＡＶＥ (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is ４００（０ｄｅｇ） (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm is 3% or less. ４００（０ｄｅｇ） and transmittance T at a wavelength of 430 nm ４３０（０ｄｅｇ） T satisfies the following relationship ４３０（０ｄｅｇ） -T ４００（０ｄｅｇ） ≧78% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ４３０－６００（０ｄｅｇ）ＡＶＥ(i-5) When the antireflection layer 1 side is the incident direction, the absolute value of the difference between the average reflectance R1430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R1430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-6) When the antireflection layer 2 side is the incident direction, the absolute value of the difference between the average reflectance R2430-600 (5 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 5 degrees and the average reflectance R2430-600 (50 deg) AVE for wavelengths of 430 to 600 nm on the spectral reflectance curve at an incident angle of 50 degrees is 4% or less. (i-7) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ７５０－１１００（０ｄｅｇ）ＡＶＥ [2] The optical filter according to [1], further satisfying the following spectral characteristic (i-8): (i-8) In the spectral transmittance curve at an incident angle of 50 degrees, the transmittance T ４００（５０ｄｅｇ） [3] The optical filter according to [1] or [2], further satisfying the following spectral characteristic (i-9): (i-9) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T ３５０－３９０（５０ｄｅｇ）ＡＶＥ [4] The optical filter according to any one of [1] to [3], further satisfying the following spectral characteristics (i-10) and (i-11): (i-10) In the spectral transmittance curve at an incident angle of 0 degrees, the minimum wavelength T at which the transmittance becomes 50% in the wavelength range of 350 to 430 nm is （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 1 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R1 (5 deg) UV50 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０ -R1 (5deg) UV50>10nm (i-11) Above T （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 2 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R2 (5 deg) UV50 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０-R2 (5 deg) UV50>10 nm [5] The optical filter according to [4], further satisfying the following spectral characteristics (i-12) to (i-14). （０ｄｅｇ）ＵＶ５０ (i-13) In the spectral transmittance curve at an incident angle of 50 degrees, the minimum wavelength T at which the transmittance is 50% in the wavelength range of 350 to 430 nm is （５０ｄｅｇ）ＵＶ５０ (i-14) The wavelength of T is in the range of 400 to 430 nm. （０ｄｅｇ）ＵＶ５０ and the T （５０ｄｅｇ）ＵＶ５０ [6] The optical filter according to any one of [1] to [5], further satisfying the following spectral characteristic (i-15): (i-15) The average transmittance T ４３０－６００（０ｄｅｇ）ＡＶＥ and the average transmittance T of the wavelength of 430 to 600 nm in the spectral transmittance curve at an incident angle of 50 degrees. ４３０－６００（５０ｄｅｇ）ＡＶＥ T satisfies the following relationship ４３０－６００（０ｄｅｇ）ＡＶＥ -T ４３０－６００（５０ｄｅｇ）ＡＶＥ ≦4.5% [7] The optical filter according to any one of [1] to [6], wherein the optical filter further satisfies the following spectral characteristics (i-16) and (i-17): (i-16) When the antireflection layer 1 side is the incident direction, in a spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R1750-1100 (5 deg) AVE for wavelengths of 750 to 1100 nm is 15% or less. (i-17) When the antireflection layer 2 side is the incident direction, in a spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R2750-1100 (5 deg) AVE for wavelengths of 750 to 1100 nm is 15% or less. [8] The optical filter according to any one of [1] to [7], wherein the UV dye comprises a merocyanine compound having a maximum absorption wavelength in the wavelength range of 370 to 410 nm in the resin. [9] The optical filter according to [8], wherein the UV dye contains a merocyanine compound represented by the following formula (M):

[0135]

[0136] [The symbols in formula (M) are defined as follows: R ２１ represents a monovalent hydrocarbon group having 1 to 16 carbon atoms which may have a substituent. ２２ ~R２５ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. ２０ is R ２６ and R ２７ represents a methylene group or an oxygen atom substituted with X ２０ represents any one of the divalent groups represented by the following formulas (X1) to (X5).

[0137]

[0138] R ２８ and R ２９ each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent, R ３０ ~R ３９ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent.]

[10] The optical filter according to any one of [1] to [9], wherein the UV dye comprises a zero methine compound having a maximum absorption wavelength in the resin at a wavelength of 350 to 380 nm.

[11] The optical filter according to

[10] , wherein the UV dye comprises a zero methine compound represented by the following formula (I):

[0139]

[0140] [The symbols in formula (I) are defined as follows: X represents an oxygen atom, a sulfur atom, or N—R １４ , or C-R １５ R １６ (R １４ ~R １６ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. １ is an alkyl group having 1 to 6 carbon atoms which may have a substituent. ２ ~R ５ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, a nitro group, an amino group, or an amide group. A represents any of the divalent groups represented by the following formulas (A1) to (A4):

[0141]

[0142] In formulas (A1) to (A4), Y is an oxygen atom or a sulfur atom, and R ６ ~R １３ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent.]

[12] The optical filter according to any one of [1] to

[11] , wherein the thickness of each of the antireflection layers 1 and 2 is 1 μm or less.

[13] The optical filter according to any one of [1] to

[12] , wherein the number of layers in each of the antireflection layers 1 and 2 is 20 or less.

[14] The optical filter according to any one of [1] to

[13] , wherein the near-infrared absorbing glass satisfies the following spectral characteristics (ii-1) and (ii-2): (ii-1) an average internal transmittance T ４５０－６００ＡＶＥ (ii-2) Average internal transmittance T of wavelength 750 to 1100 nm ７５０－１１００ＡＶＥ

[15] The optical filter according to any one of [1] to

[14] , wherein the near-infrared absorbing glass is a phosphate glass or a fluorophosphate glass containing copper ions.

[16] The optical filter according to any one of [1] to

[15] , wherein the resin film has a thickness of 5 μm or less.

[17] An imaging device comprising the optical filter according to any one of [1] to

[16] .

[0143] Next, the present invention will be described in more detail with reference to examples. Each optical property was measured using an ultraviolet-visible-near-infrared spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation). Unless otherwise specified, the spectral properties were measured at an incident angle of 0 degrees (perpendicular to the main surface).

[0144] The dyes used in each example are as follows: Compounds 1 to 8 are UV dyes, and compounds 9 to 11 are IR dyes.

[0145]

[0146]

[0147]

[0148] Compounds 1 and 2: Synthesized with reference to Japanese Patent No. 6020746. Compounds 3 and 4: Synthesized by the methods shown below. Compound 5: D5730 manufactured by Tokyo Chemical Industry Co., Ltd. was used. Compound 6: B2728 manufactured by Tokyo Chemical Industry Co., Ltd. was used. Compound 7: Tinuvin 460 manufactured by BASF Japan Ltd. was used. Compound 8: Synthesized with reference to Japanese Patent No. 6256335. Compound 9: Synthesized with reference to Japanese Patent No. 7014272. Compound 10: Synthesized with reference to Dyes and Pigments 73 (2007) 344-352. Compound 11: Synthesized with reference to Japanese Patent No. 6197940.

[0149] (Synthesis of Compound 3) (1) Synthesis of Intermediate 1 2-(methylthio)benzothiazole (25 g) and methyl p-toluenesulfonate (103 g) were placed in a 1 L recovery flask and reacted at 130°C for 5 hours. After completion of the reaction, the mixture was returned to room temperature and filtered to obtain Intermediate 1 (50.5 g) shown in the following scheme. (2) Synthesis of Compound 3 Next, Intermediate 1 (5.0 g), dimedone (2.1 g), triethylamine (2.8 g), and ethanol (130 mL) obtained above were placed in a 1 L recovery flask and reacted at room temperature for 3 hours. After completion of the reaction, the solvent was removed, and the precipitated solid was filtered and washed to obtain Compound 3 (2.4 g).

[0150]

[0151] (Synthesis of Compound 4) (1) Synthesis of Intermediate 2 1,1'-carbonylimidazole (15 g), isobutylamine (15 g), and N,N-dimethylformamide (DMF, 30 mL) were placed in a 1 L recovery flask and reacted at 75°C for 3 hours. After completion of the reaction, the mixture was returned to room temperature, acidified with 1 M aqueous hydrochloric acid, extracted, and the solvent was removed to obtain Intermediate 2 (17 g) shown in the following scheme. (2) Synthesis of Intermediate 3 Next, Intermediate 2 (17 g), malonic acid (10 g), acetic anhydride (33 g), and acetic acid (100 mL) obtained above were placed in a 1 L recovery flask and reacted at 90°C for 3 hours. After completion of the reaction, the mixture was returned to room temperature, water was added, extracted, and then purified by column chromatography to obtain Intermediate 3 (21 g) shown in the following scheme. (3) Synthesis of Compound 4 Next, intermediate 1 (5.0 g) obtained in the synthesis of compound 3 above, intermediate 3 (2.1 g) obtained above, triethylamine (2.8 g), and ethanol (130 mL) were placed in a 1 L recovery flask and reacted at room temperature for 3 hours. After completion of the reaction, the solvent was removed, and the precipitated solid was filtered and washed to obtain compound 4 (2.7 g).

[0152]

[0153] <Spectral Properties of Dye in Resin (Coated Film)> Polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Company) was dissolved in an organic solvent (cyclohexanone:γ-butyrolactone = 1:1 mass ratio) at a concentration of 8.5 mass%. Compound 1 was added to the polyimide resin solution prepared above so that the amount was 7.0 parts by mass per 100 parts by mass of the resin, and the mixture was stirred for 2 hours while heating to 50°C. The dye-containing resin solution was spin-coated onto a glass substrate (alkali glass, D263 manufactured by Schott) to obtain a coated film with a thickness of 1 μm. Coating films were also prepared in the same manner for Compounds 2 to 11.

[0154] For each of the resulting glass substrates with a coating film, the transmission spectrum (incident angle 0 degrees) and reflection spectrum (incident angle 5 degrees) were measured using a spectrophotometer in the wavelength range of 350 nm to 1200 nm. The maximum absorption wavelength was calculated from the spectral internal transmittance curve obtained using the spectral transmittance curve and the spectral reflectance curve. The results are shown in Table 3 below.

[0155]

[0156] <Spectral Properties of Phosphate Glass> Phosphate glass having the composition shown in the table below was prepared as a near-infrared absorbing glass. The spectral transmittance curve of the phosphate glass was measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The spectral properties shown in Table 4 below were calculated from the obtained spectral property data. Note that the spectral properties shown in Table 4 below were evaluated using internal transmittance to avoid the influence of reflection at the air interface and the glass interface. The spectral transmittance curve of the phosphate glass is shown in Figure 2.

[0157]

[0158] As shown above, it is clear that the near-infrared absorbing glass used has high transmittance in the visible light region and is excellent in light blocking properties in the near-infrared region.

[0159] <Spectral Characteristics of Optical Filter> [Example 1-1] Polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Company) was dissolved in an organic solvent (cyclohexanone:γ-butyrolactone = 1:1 mass ratio) at a concentration of 8.5 mass%. To this polyimide resin solution, 5.0 mass parts of compound 1, 4.7 mass parts of compound 3, 1.5 mass parts of compound 8, and 1.6 mass parts of compound 9 were added relative to 100 mass parts of resin, and the mixture was stirred for 2 hours while heated to 50°C. This dye-containing resin solution was spin-coated onto the above-mentioned phosphate glass having a thickness of 0.28 mm to obtain a glass substrate having a resin film with a film thickness of 1.6 μm. SiO was applied to the surface of this resin-coated glass substrate on which the resin film was formed (surface B). ２ and TiO ２ The anti-reflection layer was formed by laminating these layers alternately to a total thickness of 0.37 μm and consisting of a dielectric multilayer film with seven layers, and SiO ２ and TiO ２ An antireflection layer was formed from a dielectric multilayer film having 15 layers and a total thickness of 0.81 μm, by alternately laminating these layers, to obtain an optical filter of Example 1-1.

[0160] Examples 1-2 to 1-5 Optical filters were obtained in the same manner as in Example 1-1, except that the thickness of the resin film and the type and content of the dye compound were changed as shown in Table 5 below.

[0161] Example 1-6 An optical filter was obtained in the same manner as in Example 1-1, except that the dielectric multilayer film formed on the B side was an antireflection layer having a total thickness of 0.81 μm and 15 layers.

[0162] [Example 1-7] The dielectric multilayer film formed on the A-side is made of SiO ２ and TiO ２ An optical filter was obtained in the same manner as in Example 1-1, except that the reflective layers were alternately laminated to a total thickness of 5.0 μm and the number of layers was 42.

[0163] Examples 1-8 to 1-11 Optical filters were obtained in the same manner as in Example 1-1, except that the thickness of the resin film and the type and content of the dye compound were changed as shown in Table 5 below.

[0164] Example 1-12 An optical filter was obtained in the same manner as in Example 1-1, except that borosilicate glass (D263 alkali glass manufactured by SCHOTT) was used instead of phosphate glass.

[0165]

[0166] For each optical filter, spectral transmittance curves at incident angles of 0° and 50°, and spectral reflectance curves at incident angles of 5° and 50° were measured using an ultraviolet-visible spectrophotometer in the wavelength range of 350 to 1200 nm. The optical filter was configured as dielectric multilayer film 1 (side A) / near-infrared absorbing glass / resin film / dielectric multilayer film 2 (side B). From the obtained spectral characteristic data, the characteristics shown in Table 6 below were calculated. The spectral transmittance curve, spectral reflectance curve (side A), and spectral reflectance curve (side B) of the optical filter of Example 1-1 are shown in FIGS. 3 to 5, respectively. The spectral transmittance curve, spectral reflectance curve (side A), and spectral reflectance curve (side B) of the optical filter of Example 1-7 are shown in FIGS. 6 to 8, respectively. The spectral transmittance curve, spectral reflectance curve (side A), and spectral reflectance curve (side B) of the optical filter of Example 1-8 are shown in FIGS. 9 to 11, respectively. Examples 1-1 to 1-6 are working examples, and Examples 1-7 to 1-12 are comparative examples.

[0167]

[0168] The optical filters of Examples 1-1 to 1-6 have high transmittance in the visible light region, high blocking properties in the near-infrared region spanning a wide range from 700 to 1100 nm, and high blocking properties in the near-ultraviolet region. Furthermore, the change in visible light transmittance is small even at high angles of incidence, indicating that these filters suppress ripple generation. Furthermore, the change in transmittance from the ultraviolet light blocking region to the visible light transmitting region is steep, indicating that these filters are capable of sufficiently capturing the necessary visible light. The optical filter of Example 1-7 uses a reflective layer, resulting in large spectral fluctuations at high angles of incidence, resulting in large fluctuations in visible reflectance and visible transmittance. The optical filters of Examples 1-8 to 1-11 have insufficient absorption characteristics of the UV dye, resulting in light leakage in the near-ultraviolet region that should be blocked, and poor oblique incidence characteristics. The optical filter of Example 1-12 uses non-absorbing glass (borosilicate glass), resulting in poor light blocking properties in the near-infrared region.

[0169] <Lightfastness of Optical Filter> The following test was carried out to evaluate the lightfastness of the dye.

[0170] [Example 2-1] Polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Company) was dissolved in an organic solvent (cyclohexanone:γ-butyrolactone = 1:1 mass ratio) at a concentration of 8.5 mass%. To this polyimide resin solution, 7.5 mass parts of compound 2 and 7.0 mass parts of compound 11 were added relative to 100 mass parts of resin, and the mixture was stirred for 2 hours while heating to 50°C. This dye-containing resin solution was spin-coated onto borosilicate glass (D263 glass manufactured by SCHOTT) to obtain a glass substrate having a resin film with a thickness of 1.3 μm. SiO was deposited on the resin film surface of this resin-coated glass substrate. ２ and TiO ２ An antireflection layer was formed from a dielectric multilayer film having seven layers and a total thickness of 0.37 μm, by alternately laminating these layers, to obtain a filter for light resistance evaluation.

[0171] Examples 2-2 to 2-4 Filters for evaluating light resistance were obtained in the same manner as in Example 2-1, except that the type and content of the dye compound in the resin film were as shown in Table 7.

[0172] Each of the above filters was subjected to a light resistance test using a Super Xenon Weather Meter (manufactured by Suga Test Instruments Co., Ltd.) by irradiating the anti-reflection layer side with light. The irradiated light was in the wavelength range of 300 to 2450 nm, and the cumulative light intensity was 80,000 J / mm. ２ The rate of change in absorbance at 370 nm, 400 nm, 700 nm, and 750 nm before and after the light fastness test was calculated to evaluate the light fastness of the dye. The results are shown in Table 7 below. Rate of change (%) = 100 - (absorbance at each wavelength after test / absorbance at each wavelength before test × 100) Examples 2-1 to 2-4 are reference examples.

[0173]

[0174] In the above results, the smaller the fluctuation rate, the more resistant the dye compound to photodegradation and the more excellent its lightfastness. The fluctuation rate is preferably 20% or less. The results of Examples 2-1 and 2-2 show that Compounds 2 and 3 have excellent durability as UV dyes themselves, and that their use in combination with an IR dye does not affect the lightfastness of the IR dye. The results of Examples 2-1 and 2-3 show that the addition of Compound 6 increased the fluctuation rate in the IR region, thereby accelerating the photodegradation of the IR dye. The results of Example 2-4 show that Compound 8 does not affect the lightfastness of the IR dye, but its large fluctuation rate in the UV region accelerates its own photodegradation.

[0175] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2022-138362) filed on August 31, 2022, the contents of which are incorporated herein by reference.

[0176] The optical filter of the present invention suppresses ripple and stray light in the visible light region even at high incident angles, and has excellent spectral characteristics that transmit light in the visible light region and block light in the near-infrared region. The optical filter is useful for imaging devices, such as cameras and sensors for transport aircraft, which have been increasingly sophisticated in recent years.

[0177] 1B...optical filter, 10...substrate, 11...near-infrared absorbing glass, 12...resin film, 20A, 20B...dielectric multilayer film

Claims

1. An optical filter comprising a substrate, an antireflection layer 1 made of a dielectric multilayer film laminated on one main surface side of the substrate, and an antireflection layer 2 made of a dielectric multilayer film laminated on the other main surface side of the substrate, the substrate has a near infrared absorbing glass and a resin film, the resin film includes a resin, a UV dye having a maximum absorption wavelength in the resin at 350 to 410 nm, and an IR dye having a maximum absorption wavelength in the resin at 700 to 850 nm; The optical filter satisfies all of the following spectral characteristics (i-1) to (i-7). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ３５０－３９０（０ｄｅｇ）ＡＶＥ Less than 1% (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T at a wavelength of 400 nm ４００（０ｄｅｇ） Less than 3% (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the transmittance T ４００（０ｄｅｇ） and transmittance T at a wavelength of 430 nm ４３０（０ｄｅｇ） satisfies the following relationship: T ４３０（０ｄｅｇ） -T ４００（０ｄｅｇ） ≧78% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ４３０－６００（０ｄｅｇ）ＡＶＥ More than 80% (i-5) The average reflectance R1 at wavelengths of 430 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees when the antireflection layer 1 side is the incident direction. ４３０－６００（５ｄｅｇ）ＡＶＥ and the average reflectance R1 at wavelengths of 430 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees ４３０－６００（５０ｄｅｇ）ＡＶＥ The absolute value of the difference is 4% or less (i-6) The average reflectance R2 at wavelengths of 430 to 600 nm in the spectral reflectance curve at an incident angle of 5 degrees when the antireflection layer 2 side is the incident direction. ４３０－６００（５ｄｅｇ）ＡＶＥ and the average reflectance R2 at wavelengths of 430 to 600 nm in the spectral reflectance curve at an incident angle of 50 degrees ４３０－６００（５０ｄｅｇ）ＡＶＥ The absolute value of the difference is 4% or less (i-7) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T ７５０－１１００（０ｄｅｇ）ＡＶＥ Less than 2%

2. The optical filter according to claim 1 , wherein the optical filter further satisfies the following spectral characteristic (i-8): (i-8) In the spectral transmittance curve at an incident angle of 50 degrees, the transmittance T at a wavelength of 400 nm ４００（５０ｄｅｇ） Less than 3%

3. The optical filter according to claim 1 , wherein the optical filter further satisfies the following spectral characteristic (i-9): (i-9) In the spectral transmittance curve at an incident angle of 50 degrees, the average transmittance T ３５０－３９０（５０ｄｅｇ）ＡＶＥ is 1.5% or less

4. 2. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-10) and (i-11). (i-10) In the spectral transmittance curve at an incident angle of 0 degrees, the minimum wavelength T at which the transmittance is 50% in the wavelength range of 350 to 430 nm （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 1 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R1 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm is （５ｄｅｇ）ＵＶ５０ satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０ -R1 （５ｄｅｇ）ＵＶ５０ >10nm (i-11) Said T （０ｄｅｇ）ＵＶ５０ When the anti-reflection layer 2 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the maximum wavelength R2 at which the reflectance becomes 50% in the wavelength range of 350 to 430 nm is （５ｄｅｇ）ＵＶ５０ satisfies the following relationship: T （０ｄｅｇ）ＵＶ５０ -R2 （５ｄｅｇ）ＵＶ５０ >10nm

5. The optical filter according to claim 4, further satisfying the following spectral characteristics (i-12) to (i-14). (i-12) Said T （０ｄｅｇ）ＵＶ５０ is in the wavelength range of 400 to 430 nm (i-13) In the spectral transmittance curve at an incident angle of 50 degrees, the minimum wavelength T at which the transmittance is 50% in the wavelength range of 350 to 430 nm （５０ｄｅｇ）ＵＶ５０ is in the wavelength range of 400 to 430 nm (i-14) Said T （０ｄｅｇ）ＵＶ５０ And the T （５０ｄｅｇ）ＵＶ５０ The absolute value of the difference is 4 nm or less

6. The optical filter according to claim 1 , wherein the optical filter further satisfies the following spectral characteristic (i-15): (i-15) Average transmittance T of wavelengths from 430 to 600 nm in the spectral transmittance curve at an incident angle of 0 degrees ４３０－６００（０ｄｅｇ）ＡＶＥ and the average transmittance T of the wavelength of 430 to 600 nm in the spectral transmittance curve at an incident angle of 50 degrees. ４３０－６００（５０ｄｅｇ）ＡＶＥ satisfies the following relationship: T ４３０－６００（０ｄｅｇ）ＡＶＥ -T ４３０－６００（５０ｄｅｇ）ＡＶＥ ≦4.5%

7. The optical filter according to claim 1 , further satisfying the following spectral characteristics (i-16) and (i-17). (i-16) When the anti-reflection layer 1 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R1 at wavelengths of 750 to 1100 nm ７５０－１１００（５ｄｅｇ）ＡＶＥ is 15% or less (i-17) When the anti-reflection layer 2 side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance R2 at wavelengths of 750 to 1100 nm ７５０－１１００（５ｄｅｇ）ＡＶＥ is 15% or less

8. 2. The optical filter according to claim 1, wherein the UV dye comprises a merocyanine compound having a maximum absorption wavelength in the resin at wavelengths of 370 to 410 nm.

9. 9. The optical filter of claim 8, wherein the UV dye comprises a merocyanine compound represented by formula (M): 【Chemistry 1】 [The symbols in formula (M) are defined as follows: R ２１ represents a monovalent hydrocarbon group having 1 to 16 carbon atoms which may have a substituent. R ２２ ~R ２５ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. Y ２０ is R ２６ and R ２７ represents a methylene group or an oxygen atom substituted with X ２０ represents any one of the divalent groups represented by the following formulas (X1) to (X5). 【Chemistry 2】 R ２８ and R ２９ each independently represents a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent; R ３０ ~R ３９ each independently represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may have a substituent.

10. 2. The optical filter according to claim 1, wherein the UV dye comprises a zeromethine compound having a maximum absorption wavelength in the resin at a wavelength of 350 to 380 nm.

11. 11. The optical filter of claim 10, wherein the UV dye comprises a zero methine compound represented by formula (I): 【Chemistry 3】 [The symbols in formula (I) are defined as follows: X is an oxygen atom, a sulfur atom, or N-R １４ , or C-R １５ R １６ (R １４ ~R １６ each independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent. R １ is an alkyl group having 1 to 6 carbon atoms which may have a substituent. R ２ ~R ５ each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, a nitro group, an amino group, or an amido group. A represents any one of the divalent groups represented by the following formulas (A1) to (A4). 【Chemistry 4】 In formulas (A1) to (A4), Y is an oxygen atom or a sulfur atom, and R ６ ~R １３ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may have a substituent.

12. 2. The optical filter according to claim 1, wherein the anti-reflection layer 1 and the anti-reflection layer 2 each have a thickness of 1 [mu]m or less.

13. 2. The optical filter according to claim 1, wherein the number of layers of said antireflection layer 1 and said antireflection layer 2 is 20 or less.

14. 2. The optical filter according to claim 1, wherein the near infrared absorbing glass satisfies the following spectral characteristics (ii-1) and (ii-2): (ii-1) Average internal transmittance T for wavelengths of 450 to 600 nm ４５０－６００ＡＶＥ More than 80% (ii-2) Average internal transmittance T for wavelengths of 750 to 1100 nm ７５０－１１００ＡＶＥ Less than 5%

15. 2. The optical filter according to claim 1, wherein the near infrared absorbing glass is a phosphate glass or a fluorophosphate glass containing copper ions.

16. 2. The optical filter according to claim 1, wherein the resin film has a thickness of 5 [mu]m or less.

17. An imaging device comprising the optical filter according to any one of claims 1 to 16.

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