JP7647756B2 - Optical Filters - Google Patents

Description

The present invention relates to an optical filter that transmits light in the visible wavelength range and blocks light in the near-infrared wavelength range.

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 near-infrared wavelength range (hereinafter also referred to as "near-infrared light").

Such optical filters include various types, such as a reflective filter in which dielectric thin films with different refractive indices are alternately stacked on one or both sides of a transparent substrate (dielectric multilayer film) and the light to be blocked is reflected by optical interference. Optical filters with a dielectric multilayer film have problems such as changes in the spectral transmittance curve depending on the incident angle, light leakage in which near-infrared light that should have a high reflectance at a high incident angle becomes highly transmittant, and noise due to near-infrared light reflected by the dielectric multilayer film, because the optical film thickness of the dielectric multilayer film changes depending on the incident angle of light. When such a filter is used, the spectral sensitivity of the solid-state imaging element may be affected by the incident angle. Therefore, there has been a demand for an optical filter that blocks near-infrared light without affecting the transmittance of visible light and without depending on the incident angle.

Here, Patent Document 1 describes an optical filter having a layer containing a near-infrared absorbing dye to reduce incidence angle dependency.

International Publication No. 2019/168090

However, the optical filter described in Patent Document 1 has room for improvement in terms of transmittance in the visible light region.
Therefore, an object of the present invention is to provide an optical filter that maintains high transmittance of visible light, particularly blue light, while suppressing a decrease in the near-infrared light shielding ability at high incident angles, such as light leakage, while blocking near-infrared light.

The present invention provides an optical filter having the following configuration.
[1] An optical filter comprising a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate,
the substrate includes a resin film containing a dye (A) that is a near-infrared absorbing dye and a resin,
The dye (A) is an optical filter which satisfies all of the following spectral characteristics (i-1) to (i-4) in a spectral transmittance curve of a coating film obtained by dissolving the dye (A) in the resin and coating the coating film on an alkali glass plate.
(i-1) When the shortest wavelength at which the transmittance is 30% in the wavelength range of 600 to 800 nm is defined as IR30a, and the longest wavelength at which the transmittance is 30% in the wavelength range of 700 to 1200 nm is defined as IR30b,
The absolute value of the difference between IR30a and IR30b is 170 nm or more (i-2). When IR50a is the shortest wavelength at which the transmittance is 50% in the wavelength range of 600 to 800 nm, and IR50b is the longest wavelength at which the transmittance is 50% in the wavelength range of 700 to 1200 nm,
The absolute value of the difference between IR50a and IR50b is 200 nm or more. (i-3) The relationship between the absorbance A ₄₄₀ at a wavelength of 440 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₄₀ /A ₇₀₀ ≦0.14.
(i-4) The relationship between the absorbance A ₄₉₀ at a wavelength of 490 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₉₀ /A ₇₀₀ ≦0.10.

According to the present invention, an optical filter can be provided that has high transmittance for visible light and high blocking ability for near-infrared light, and in particular, has high transmittance for blue light and suppresses the decrease in blocking ability for near-infrared light at high angles of incidence.

FIG. 1 is a cross-sectional view illustrating an example of an optical filter according to an embodiment. FIG. 2 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 3 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 4 is a cross-sectional view illustrating a schematic configuration of another example of the optical filter according to the embodiment. FIG. 5 is a diagram showing the spectral transmittance curve of Compound 6 in dichloromethane and in a cycloolefin resin. FIG. 6 is a diagram showing the spectral transmittance curve of the optical filter of Example 3-1.

Hereinafter, an embodiment of the present invention will be described.
In this specification, the near-infrared absorbing dye may be abbreviated as "NIR dye" and the ultraviolet absorbing dye may be abbreviated as "UV dye".
In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. The dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. In addition, the group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

In this specification, the internal transmittance is the transmittance obtained by subtracting the influence of interface reflection from the actually measured transmittance, which is expressed by the formula {actual transmittance/(100-reflectance)}×100.
In this specification, the transmittance of a substrate and the transmittance of a resin film including a case where a dye is contained in the resin are all "internal transmittance" even when they are described as "transmittance". On the other hand, the transmittance measured by dissolving a dye in a solvent such as dichloromethane and the transmittance of an optical filter having a dielectric multilayer film are actually measured transmittances.

In this specification, absorbance is converted from (internal) transmittance using the formula -log10((internal) transmittance/100).

In this specification, for example, a transmittance of 90% or more in a specific wavelength range means that the transmittance is not below 90% in the entire wavelength range, i.e., the minimum transmittance is 90% or more in the wavelength range. Similarly, for example, a transmittance of 1% or less in a specific wavelength range means that the transmittance is not more than 1% in the entire wavelength range, i.e., the maximum transmittance is 1% or less in the 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 the wavelength range.
In this specification, any numerical range expressed by "to" includes the upper and lower limits.

<Optical filter>
An optical filter according to one embodiment of the present invention (hereinafter also referred to as "the present filter") includes a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate.

An example of the configuration of the present filter will be described with reference to the drawings. Figures 1 to 4 are cross-sectional views that show schematic diagrams of an example of an optical filter according to an embodiment.
1 is an example of an optical filter 1A having a dielectric multilayer film 30 on one main surface side of a substrate 10. Note that "having a specific layer on the main surface side of the substrate" does not only mean that the layer is provided in contact with the main surface of the substrate, but also includes that another functional layer is provided between the substrate and the layer.

The optical filter 1B shown in Figure 2 is an example having a dielectric multilayer film 30 on both main surfaces of the substrate 10.

The optical filter 1C shown in Figure 3 is an example in which the substrate 10 has a support 11 and a resin film 12 laminated on one of the main surfaces of the support 11. The optical filter 1C further has a dielectric multilayer film 30 on the resin film 12 and on the main surface of the support 11 on which the resin film 12 is not laminated.

The optical filter 1D shown in Figure 4 is an example in which the substrate 10 has a support 11 and resin films 12 laminated on both main surfaces of the support 11. The optical filter 1D further has a dielectric multilayer film 30 on each of the resin films 12.

<Substrate>
In the optical filter of the present invention, the substrate includes a dye (A) and a resin. Preferably, the substrate includes a resin film including the dye (A) and a resin.

<NIR dye (A)>
The dye (A) is a near-infrared absorbing (NIR) dye. When the substrate contains a dye that absorbs near-infrared rays, the degradation of the spectral characteristics of the dielectric multilayer film at a high incidence angle, for example, the occurrence of light leakage and noise in the near-infrared region, can be suppressed by the absorption characteristics of the substrate.

It is preferable that the dye (A) has a maximum absorption wavelength in dichloromethane between 600 and 900 nm.

The dye (A) exhibits specific spectral characteristics in the resin used for the substrate. Specifically, the coating film formed by dissolving the dye (A) in a resin and coating the resin on an alkaline glass plate satisfies all of the following spectral characteristics (i-1) to (i-4).

(i-1) When the shortest wavelength at which the transmittance is 30% in the wavelength range of 600 to 800 nm is defined as IR30a, and the longest wavelength at which the transmittance is 30% in the wavelength range of 700 to 1200 nm is defined as IR30b,
The absolute value of the difference between IR30a and IR30b is 170 nm or more (i-2). When IR50a is the shortest wavelength at which the transmittance is 50% in the wavelength range of 600 to 800 nm, and IR50b is the longest wavelength at which the transmittance is 50% in the wavelength range of 700 to 1200 nm,
The absolute value of the difference between IR50a and IR50b is 200 nm or more. (i-3) The relationship between the absorbance A ₄₄₀ at a wavelength of 440 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₄₀ /A ₇₀₀ ≦0.14.
(i-4) The relationship between the absorbance A ₄₉₀ at a wavelength of 490 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₉₀ /A ₇₀₀ ≦0.10.

This filter, which contains a dye (A) that exhibits the above-mentioned spectral characteristics (i-1) to (i-4) in a resin, is an optical filter that maintains good transmittance of visible light, particularly blue light, while suppressing the decrease in blocking ability of near-infrared light at high angles of incidence.

Satisfying the spectral characteristics (i-1) and (i-2) means that near-infrared light can be absorbed broadly over a wide wavelength range. This makes it possible to efficiently prevent light leakage in the 750-900 nm wavelength band, where light leakage is likely to occur due to the inability of the dielectric multilayer film to completely block light at high angles of incidence. Furthermore, since the dye (A) itself has broad absorption characteristics in the resin, it is possible to efficiently block the near-infrared region using only the dye (A) while maintaining good transmittance in the visible light region without combining multiple types of NIR dyes. Combining multiple types of NIR dyes can block a wide range of near-infrared light, but the transmittance in the visible light region also tends to decrease at the same time, but this can be avoided by using the dye (A) in the present invention.

The absolute value of the spectral characteristic (i-1) is preferably 190 nm or more, more preferably 210 nm or more, and particularly preferably 230 nm or more. Since a wider absorption width is more preferable, there is no upper limit, but it is usually 270 nm or less.
The absolute value of the spectral characteristic (i-2) is preferably 210 nm or more, more preferably 230 nm or more. Since a wider absorption width is more preferable, the upper limit is not limited, but is usually 270 nm or less.

Satisfying the spectral characteristics (i-3) and (i-4) means that the transmittance of blue light is excellent.
The spectroscopic characteristic (i-3) preferably satisfies A ₄₄₀ /A ₇₀₀ ≦0.11, and more preferably A ₄₄₀ /A ₇₀₀ ≦0.10.
The spectroscopic characteristic (i-4) preferably satisfies A ₄₉₀ /A ₇₀₀ ≦0.08, and more preferably satisfies A ₄₉₀ /A ₇₀₀ ≦0.07.

It is preferred that the dye (A) further exhibits the following spectroscopic property (i-5) in the resin. That is, it is preferred that the coating film containing the dye (A) and the resin satisfies the following spectroscopic property (i-5).
(i-5) The product of the content of the dye (A) in the coating film and the thickness of the coating film is 20 (mass% μm) or less. By satisfying the spectroscopic characteristic (i-5), the content of the NIR dye (A) can absorb near-infrared light at least in a wide wavelength range. The spectroscopic characteristic (i-5) is preferably 15 (mass% μm) or less, more preferably 12 (mass% μm) or less, and also preferably 1 (mass% μm) or more.

It is preferred that the dye (A) further exhibits the following spectroscopic property (i-6) in the resin. That is, it is preferred that the coating film containing the dye (A) and the resin satisfies the following spectroscopic property (i-6).
(i-6) The relationship between A ₅₇₀ at a wavelength of 570 nm and absorbance A ₇₀₀ at a wavelength of 700 nm is A ₅₇₀ /A ₇₀₀ ≦0.10
Satisfying the spectral characteristic (i-6) means that the transparency of green light is excellent. The spectral characteristic (i-6) is preferably A ₅₇₀ /A ₇₀₀ ≦0.05, and more preferably A ₅₇₀ /A ₇₀₀ ≦0.03.

It is preferred that the dye (A) further exhibits the following spectroscopic property (i-7) in the resin. That is, it is preferred that the coating film containing the dye (A) and the resin satisfies the following spectroscopic property (i-7).
(i-7) The relationship between the absorbance A ₆₃₀ at a wavelength of 630 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₆₃₀ /A ₇₀₀ ≦0.12.
Satisfying the spectral characteristic (i-7) means that the transmittance of red light is excellent. The spectral characteristic (i-7) preferably satisfies A ₆₃₀ /A ₇₀₀ ≦0.11, and more preferably satisfies A ₆₃₀ /A ₇₀₀ ≦0.08.

It is preferable that the dye (A) further exhibits the following spectroscopic property (i-8) in the resin. That is, it is preferable that the coating film containing the dye (A) and the resin satisfies the following spectroscopic property (i-8).
(i-8) The average internal transmittance T _700-800 in the spectral transmittance curve for wavelengths of 700 to 800 nm is 2 to 25%.
Satisfying the spectral characteristic (i-8) means that light leakage at high incidence can be suppressed. The spectral characteristic (i-8) is preferably 2 to 20%, and more preferably 2 to 18%.

It is preferable that the dye (A) further satisfies the following properties (ii-1) and (ii-2).
In a spectral transmittance curve measured by dissolving the dye (A) in dichloromethane so that the transmittance at the maximum absorption wavelength is 10%, the shortest wavelength at which the transmittance is 30% within a wavelength range of 600 to 900 nm is designated as IR30a _(DIC) , the longest wavelength at which the transmittance is 30% is designated as IR30b _(DIC) , the shortest wavelength at which the transmittance is 50% is designated as IR50a _(DIC) , and the longest wavelength at which the transmittance is 50% is designated as IR50b _(DIC) .
In the spectral transmittance curve of a coating film obtained by dissolving the dye (A) in the resin and coating the coating on an alkali glass plate so that the transmittance at the maximum absorption wavelength is 10%, the shortest wavelength at which the transmittance is 30% within the wavelength range of 600 to 900 nm is defined as IR30a _(PO) , the longest wavelength at which the transmittance is 30% is defined as IR30b _(PO) , the shortest wavelength at which the transmittance is 50% is defined as IR50a _(PO) , and the longest wavelength at which the transmittance is 50% is defined as IR50b _(PO) ,
(ii-1) The absolute value of the difference between IR30a _(PO) and IR30b _(PO) is 2.8 times or more the absolute value of the difference between IR30a _(DIC) and IR30b _(DIC). (ii-2) The absolute value of the difference between IR50a _(PO) and IR50b (PO ₎ is 3 times or more the absolute value of the difference between IR50a _(DIC) and IR50b _(DIC) . By satisfying the spectroscopic properties (ii-1) and (ii-2), it is meant that the dye (A) has a significantly wider absorption width in the resin than in dichloromethane in the near infrared light absorption band of 600 to 900 nm. Here, the resin is the same as the resin contained in the substrate.
The absolute value of the spectral characteristic (ii-1) is more preferably 3 times or more, and particularly preferably 4 times or more.
The absolute value of the spectral characteristic (ii-2) is more preferably 3.2 times or more, and particularly preferably 4 times or more.

As the dye (A), a cyanine dye is preferred, and an external salt type cyanine dye having an anionic group outside the molecule is more preferred. External salt type cyanine dyes form an association state in the resin and tend to broaden the near-infrared absorption band, so they tend to satisfy the above-mentioned spectroscopic characteristics (i-1) to (i-8), (ii-1), and (ii-2).

Specifically, the cyanine dye is preferably a compound shown in the following formula (A1) or a compound shown in the following formula (A2).

In the formulae (A1) and (A2), the symbols are as follows:
R ¹⁰¹ to R ¹⁰⁹ and R ¹²¹ to R ¹³¹ each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹¹⁰ to ¹¹⁴ and R ¹³² to ¹³⁶ each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 15 carbon atoms.
X ⁻ represents a monovalent anion.
n1 and n2 each independently represent 0 or 1. A hydrogen atom bonded to the carbocycle containing -(CH ₂ ) _n1 - and the carbocycle containing -(CH ₂ ) _n2 - may be substituted with a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms.

In formula (A1) and formula (A2), R ¹⁰² to R ¹⁰⁵ , R ¹⁰⁸ , R ¹⁰⁹ , R ¹²² to R ¹²⁷ , R ¹³⁰ and R ¹³¹ each independently represent preferably a hydrogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms, and more preferably a hydrogen atom from the viewpoint of obtaining a high visible light transmittance.

In formulae (A1) and (A2), R ¹¹⁰ to R ¹¹⁴ and R ¹³² to R ¹³⁶ each independently preferably represent a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, and more preferably a hydrogen atom from the viewpoint of obtaining a high visible light transmittance.

R ¹⁰⁶ , R ¹⁰⁷ , R ¹²⁸ and R ¹²⁹ are each independently preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic or branched alkyl group), more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. It is also preferable that R ¹⁰⁶ and R ¹⁰⁷ , and R ¹²⁸ and R ¹²⁹ are the same group.

R ¹⁰¹ and R ¹²¹ are preferably an alkyl group having 1 to 15 carbon atoms or an aryl group having 5 to 20 carbon atoms, and more preferably a branched alkyl group having 1 to 15 carbon atoms from the viewpoint of maintaining a high visible light transmittance in the transparent resin as in the solution.

Examples of X ⁻ include I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , or an anion represented by the formula (X1) or (X2), and preferably BF ₄ ⁻ or PF ₆ ⁻ .

In the following description, the portion of the dye (A1) excluding R ¹⁰¹ to R ¹¹⁴ is also referred to as the skeleton (A1). The same applies to other dyes.

In formula (A1), the compound where n1 is 1 is shown in formula (A11) below, and the compound where n1 is 0 is shown in formula (A12) below.

In formula (A11) and formula (A12), R ¹⁰¹ to R ¹¹⁴ and X ^- are the same as in formula (A1). R ¹¹⁵ to R ¹²⁰ each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹¹⁵ to R ¹²⁰ each independently represent preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic, or branched alkyl group), more preferably a hydrogen atom, or an alkyl group having 1 to 15 carbon atoms. In addition, it is preferable that R ¹¹⁵ to R ¹²⁰ are the same group.

In formula (A2), the compound where n2 is 1 is shown in formula (A21) below, and the compound where n2 is 0 is shown in formula (A22) below.

In formula (A21) and formula (A22), R ¹²¹ to R ¹³⁶ and X ^- are the same as in formula (A2). R ¹³⁷ to R ¹⁴² each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹³⁷ to R ¹⁴² each independently represent preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms (which may include a linear, cyclic, or branched alkyl group), more preferably a hydrogen atom, or an alkyl group having 1 to 15 carbon atoms. In addition, it is preferable that R ¹³⁷ to R ¹⁴² are the same group.

More specifically, the compounds represented by formula (A11), formula (A12), formula (A21), and formula (A22) each include compounds in which an atom or group bonded to each skeleton is an atom or group shown in the following Tables 1 to 4. In all the compounds shown in Tables 1 and 2, R ¹⁰¹ to R ¹⁰⁹ are all the same on the left and right sides of the formula. In all the compounds shown in Tables 3 and 4, R ¹²¹ to R ¹³¹ are the same on the left and right sides of the formula.

In Table 1, R ¹⁰² -R ¹⁰⁵ , R ¹¹⁰ -R ¹¹⁴ , and R ¹¹⁵ -R ¹²⁰ , in Table 2, R ¹⁰² -R ¹⁰⁵ , R ¹¹⁰ -R ¹¹⁴ , and R ¹¹⁵ -R ¹¹⁸ , in Table 2, R ¹²² -R ¹²⁷ , R ¹³² -R ¹³⁶ , and R ¹³⁷ -R ¹⁴³ , in Table 3, and R ¹²² -R ¹²⁷ , R ¹³² -R ¹³⁶ , and R ¹³⁷ -R ¹⁴⁰ in Table 4, are represented as "H" when all are hydrogen atoms.

As the dye (A11), from the viewpoints of synthesis, solubility in the resin, heat resistance, and light resistance, (A11-1) to (A11-4), (A11-9) to (A11-12), and (A11-17) to (A11-20) are preferred.

As the dye (A12), (A12-1) to (A12-4), (A12-9) to (A12-12), and (A12-17) to (A12-20) are preferred from the viewpoints of synthesis, solubility in the resin, heat resistance, and light resistance.

As the dye (A21), from the viewpoints of synthesis, solubility in the resin, heat resistance, and light resistance, (A21-1) to (A21-4), (A21-9) to (A21-12), and (A21-17) to (A21-20) are preferred.

As the dye (A22), from the viewpoints of synthesis, solubility in the resin, heat resistance, and light resistance, (A22-1) to (A22-4), (A22-9) to (A22-12), and (A22-17) to (A22-20) are preferred. In particular, (A22-17) to (A22-20) are preferred from the viewpoints of broadness and maximum absorption wavelength, as they can block light in a broad band from 700 to 850 nm, and can maintain a high visible transmittance.

Dye (A1) and dye (A2) can be produced, for example, by the methods described in Dyes and Pigments 73 (2007) 344-352 and J. Heterocyclic Chem, 42, 959 (2005).

The resin film may contain one of the pigments (A1) and (A2) alone, or a combination of two or more of them.

The content of dye (A) in the resin film is preferably 2 to 25 parts by mass, and more preferably 2 to 20 parts by mass, per 100 parts by mass of resin, from the viewpoint of achieving the desired spectral characteristics without degrading the resin properties.

<NIR dye (B)>
The substrate in the optical film of the present invention may further contain, as an NIR dye, a dye (B) having a maximum absorption wavelength in dichloromethane at 600 to 900 nm in addition to the dye (A), thereby making it possible to more efficiently block near-infrared light.

As the dye (B), at least one selected from the group consisting of squarylium 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, chloroquinium dyes, tetradehydrocoline dyes, triphenylmethane dyes, aminium dyes and diimmonium dyes is preferred.

It is preferable that the dye (B) contains at least one dye selected from a squarylium dye, a phthalocyanine dye, and a diimmonium dye.

As the squarylium dye, the compound shown in the following formula (I) is preferred.

In the formula (I), the symbols are as follows:
R ²⁴ and R ²⁶ each independently represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, -NR ²⁷ R ²⁸ (R ²⁷ and R ²⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -C(=O)-R ²⁹ (R ²⁹ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 11 carbon atoms, or an aryl group having 7 to 18 carbon atoms which may have a substituent and may have an oxygen atom between the carbon atoms), -NHR ³⁰ , or -SO ₂ -R ³⁰ (R and ^{R 30} each represent a hydrocarbon group having 1 to 25 carbon atoms, in which one or more hydrogen atoms may be substituted with a halogen atom, a hydroxyl group, a carboxy group, a sulfo group, or a cyano group, and which may contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms), or a group represented by the following formula (S) (R ⁴¹ and R ⁴² each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 10 carbon atoms; k is 2 or 3).

R ²¹ and R ²² , R ²² and R ²⁵ , and R ²¹ and R ²³ may be linked to each other to form, together with the nitrogen atom, a 5- or 6-membered heterocycle A, a heterocycle B, and a heterocycle C, respectively.

When a heterocycle A is formed, R ²¹ and R ²² bond to each other to form a divalent group -Q-, which is an alkylene group in which the hydrogen atom may be substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent, or an alkyleneoxy group.

R ²² and R ²⁵ when heterocycle B is formed, and R ²¹ and R ²³ when heterocycle C is formed, are bonded to divalent groups -X ¹ -Y ¹ - and -X ² -Y ² - (X ¹ and X ² are the sides bonded to the nitrogen), where X ¹ and X ² are each a group represented by the following formula (1x) or (2x), and Y ¹ and Y ² are each a group selected from the following formulas (1y) to (5y). When ^{X 1} and X ² are each a group represented by the following formula (2x), Y ¹ and Y ² may each be a single bond, in which case there may be an oxygen atom between the carbon atoms.

In formula (1x), the four Z's each independently represent a hydrogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, or ^-NR38R39 ( ^{R38 and R39} each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). ^R31 to ^R36 each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and ^R37 represents an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

R ²⁷ , R ²⁸ , R ²⁹ , R ³¹ to R 37 , R ²¹ to R ²³ when not forming a heterocycle, and R ²⁵ may be bonded to any of the others to form a ^{5- or 6-membered ring. R 31 and} R ³⁶ , and R ³¹ and R ³⁷ may be directly bonded to each other.

When no heterocycle is formed, R ²¹ and R ²² each independently represent a hydrogen atom, an alkyl group or aryl group having 1 to 6 carbon atoms which may have a substituent, or an aryl group or araryl group having 6 to 11 carbon atoms which may have a substituent. When no heterocycle is formed, R ²³ and R ²⁵ each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 6 carbon atoms.

As compound (I), for example, a compound represented by formula (I-1) is preferred from the viewpoint of increasing the visible light transmittance.

The symbols in formula (I-1) have the same definitions as those of the same symbols in formula (I), and the preferred embodiments are also the same.

In compound (I-1), X ¹ is preferably a group (2x), and Y ¹ is preferably a single bond or a group (1y). In this case, R ³¹ to R ³⁶ are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group. Specific examples of -Y ¹ -X ¹ - include divalent organic groups represented by formulas (11-1) to (12-3).

-C(CH ₃ ) ₂ -CH(CH ₃ )-...(11-1)
-C( _CH3 ) ₂ - _CH2 -...(11-2)
-C( _CH3 ) ₂ -CH( _C2H5 ) _-... (11-3)
-C _{( CH3} ) ₂ -C( _CH3 )( _nC3H7 )-...(11-4)
-C( _CH3 ) ₂ - _CH2 - _CH2 -...(12-1)
-C(CH ₃ ) ₂ -CH ₂ -CH(CH ₃ )-...(12-2)
-C( _CH3 ) ₂ -CH( _CH3 )-CH2 _-... (12-3)

In addition, in compound (I-1), from the viewpoints of solubility, heat resistance, and steepness of change in the vicinity of the boundary between the visible range and the near infrared range in the spectral transmittance curve, R ²¹ is more preferably independently a group represented by formula (4-1) or formula (4-2).

In formula (4-1) and formula (4-2), R ⁷¹ to R ⁷⁵ independently represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

Compound (I) can be prepared by known methods, for example, as described in U.S. Pat. No. 5,543,086, U.S. Patent Application Publication No. 2014/0061505, and WO 2014/088063.

Examples of phthalocyanine dyes include the phthalocyanine dyes described in Japanese Patent No. 5,884,953 and International Publication No. 2019/168090.

Examples of diimmonium dyes include the diimmonium dyes described in WO 2014/168189.

The resin film may contain one type of dye (B) alone or a combination of two or more types.

The content of dye (B) in the resin film is preferably 2 to 25 parts by weight, more preferably 2 to 20 parts by weight, per 100 parts by weight of resin.

<Other dyes>
In addition to the NIR dye, the substrate may contain other dyes, for example UV dyes.
Specific examples of the UV dye include oxazole-based, merocyanine-based, cyanine-based, naphthalimide-based, oxadiazole-based, oxazine-based, oxazolidine-based, naphthalic acid-based, styryl-based, anthracene-based, cyclic carbonyl-based, triazole-based dyes, etc. Furthermore, the UV dye may be used alone or in combination of two or more kinds.

<Base material composition>
The substrate in the present filter may have a single-layer structure or a multi-layer structure, and the material of the substrate is not particularly limited and may be an organic or inorganic material as long as it is a transparent material that transmits visible light of 400 to 700 nm.
When the substrate has a single layer structure, a resin substrate made of a resin film containing a resin and the NIR dye (A) is preferred.
When the substrate has a multi-layer structure, it is preferably a composite substrate having a resin film containing the NIR dye (A) laminated on at least one main surface of the support. In this case, the support is preferably made of a transparent resin or a transparent inorganic material.

The resin in the resin layer is preferably a transparent resin. As a transparent resin, a polymer composed of an alicyclic compound is preferable from the viewpoint that the NIR dye (A) forms an aggregated state and the near-infrared light absorption band is easily broadened. Examples of such polymers include cyclic alkane resins and cyclic olefin resins. These resins may be used alone or in combination of two or more.

When the substrate contains the NIR dye (B) or other dyes, these dyes may be contained in the resin film containing the NIR dye (A) or may be contained in another resin film. When another resin film is laminated, the transparent resin is one or more transparent resins selected from polyester resin, acrylic resin, epoxy resin, ene-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamideimide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin.

As the transparent inorganic material, glass or a crystalline material is preferable.
Examples of glass that can be used for the support include absorbing glass (near-infrared absorbing glass) containing copper ions in phosphate glass or phosphate glass, soda-lime glass, borosilicate glass, alkali-free glass, quartz glass, etc. As the glass, absorbing glass is preferable depending on the purpose, and phosphate glass and phosphate glass are preferable from the viewpoint of absorbing infrared light. When it is desired to capture a large amount of red light (600 to 700 nm), alkali glass, alkali-free glass, and quartz glass are preferable. Note that "phosphate glass" also includes silicophosphate glass, in which part of the glass skeleton is composed of _SiO2 .

The glass may be chemically strengthened glass obtained by exchanging alkali metal ions (e.g., Li ions, Na ions) having a small ionic radius present on the main surface of the glass plate with alkali ions having a larger ionic radius (e.g., Na ions or K ions for Li ions, and K ions for Na ions) through ion exchange at a temperature below the glass transition point.

Crystalline materials that can be used for the support include birefringent crystals such as quartz, lithium niobate, and sapphire.

As a support, inorganic materials are preferred, in terms of shape stability related to long-term reliability of spectroscopic characteristics, mechanical properties, etc., and handling properties during filter production, and glass and sapphire are particularly preferred.

The resin film can be formed by dissolving or dispersing the dye (A), the resin or the raw material components of the resin, and each component that is mixed as necessary in a solvent to prepare a coating liquid, applying this to a support, drying it, and further curing it as necessary. The support may be the support included in this filter, or it may be a peelable support used only when forming the resin film. The solvent may be a dispersion medium in which the dye can be stably dispersed or a solvent in which the dye can be dissolved.

The coating liquid may also contain a surfactant to improve voids caused by tiny bubbles, depressions caused by the adhesion of foreign matter, and repellency during the drying process. For example, the dip coating method, cast coating method, spin coating method, etc. can be used to apply the coating liquid. After the coating liquid is applied onto the support, a resin film is formed by drying. If the coating liquid contains raw materials for a transparent resin, a curing process such as heat curing or light curing is further performed.

The resin film can also be manufactured into a film by extrusion molding. When the substrate is a single-layer structure (resin substrate) consisting of a resin film containing dye (A), the resin film can be used as is as the substrate. When the substrate is a multi-layer structure (composite substrate) having a support and a resin film containing dye (A) laminated on at least one main surface of the support, the substrate can be manufactured by laminating this film onto the support and integrating them by thermocompression or the like.

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, each layer may have the same or different configurations.

When the substrate is a multi-layer structure (composite substrate) having a support and a resin film containing the dye (A) and a resin, the thickness of the resin film is preferably 5 μm or less, more preferably 3 μm or less. The thickness of the resin film is preferably 0.5 μm or more. When the resin film is made of multiple layers, the total thickness of the layers is preferably 0.5 to 10 μm.
When the substrate has a single layer structure (resin substrate) made of a resin film containing the dye (A), the thickness of the resin film is preferably 50 to 300 μm.
The optical filter of the present invention contains an NIR dye (A) that satisfies specific spectral characteristics, and thus can block near-infrared light over a wide range efficiently even with a small dye content. This allows the resin film containing the dye (A) to be made thinner.

The shape of the substrate is not particularly limited, and may be a block, plate, or film.
In addition, the thickness of the substrate is preferably 300 μm or less from the viewpoints of reducing warpage during formation of the dielectric multilayer film and reducing the height of the optical filter. When the substrate is a resin substrate made of a resin film, the thickness is preferably 50 to 300 μm. When the substrate is a composite substrate comprising a support and a resin film, the thickness is preferably 100 to 300 μm.

<Dielectric multilayer film>
In the present filter, the dielectric multilayer film is laminated as an outermost layer on at least one of the main surfaces of the substrate.

In this filter, at least one of the dielectric multilayer films is preferably designed as a near-infrared reflective layer (hereinafter also referred to as an NIR reflective layer). The other of the dielectric multilayer films is preferably designed as an NIR reflective layer, a reflective layer having a reflection range other than the near-infrared range, or an anti-reflection layer.

The NIR reflective layer is a dielectric multilayer film designed to block light in the near-infrared range. The NIR reflective layer has wavelength selectivity that transmits visible light and mainly reflects light in the near-infrared range other than the light-shielding range of the resin film. The reflective region of the NIR reflective layer may include a light-shielding region in the near-infrared range of the resin film. The NIR reflective layer is not limited to NIR reflection characteristics, and may be appropriately designed to further block light in wavelength ranges other than the near-infrared range, for example, the near-ultraviolet range.

The NIR reflective layer is, for example, composed of a dielectric multilayer film in which a dielectric film with a low refractive index (low refractive index film) and a dielectric film with a high refractive index (high refractive index film) are alternately laminated. The high refractive index film preferably has a refractive index of 1.6 or more, more preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta ₂ O ₅ , TiO ₂ , and Nb ₂ O _5. Among these, TiO ₂ is preferred from the viewpoints of film formation, reproducibility in refractive index, stability, etc.

On the other hand, 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 materials for the low refractive index film include _SiO2 and _SiOxNy . _SiO2 is preferred from the standpoint of reproducibility, stability, economy, etc. in film formation.

Furthermore, it is preferable that the NIR reflective layer has a steep change in transmittance in the boundary wavelength region between the transmission region and the light blocking region. For this purpose, the total number of laminated layers of the dielectric multilayer film constituting the reflective layer is preferably 15 layers or more, more preferably 25 layers or more, and even more preferably 30 layers or more. However, since a large total number of laminated layers can cause warping or an increase in film thickness, the total number of laminated layers is preferably 100 layers or less, more preferably 75 layers or less, and even more preferably 60 layers or less. Furthermore, the film thickness of the reflective layer as a whole is preferably 2 to 10 μm.

If the total number of layers and the thickness of the dielectric multilayer film are within the above ranges, the NIR reflective layer satisfies the requirements for miniaturization and can suppress the incidence angle dependency while maintaining high productivity. In addition, the dielectric multilayer film can be formed using, for example, a vacuum film formation process such as a CVD method, a sputtering method, or a vacuum deposition method, or a wet film formation process such as a spray method or a dip method.

The NIR reflective layer may be one layer (a group of dielectric multilayer films) that provides a predetermined spectral characteristic, or two layers that provide a predetermined spectral characteristic. When there are two or more layers, each reflective layer may have the same or different configurations. When there are two or more reflective layers, they are usually composed of multiple reflective layers with different reflection bands. When two reflective layers are provided, one may be a near-infrared reflective layer that blocks light in the short wavelength band of the near-infrared region, and the other may be a near-infrared/near-ultraviolet reflective layer that blocks light in both the long wavelength band of the near-infrared region and the near-ultraviolet region.

Examples of anti-reflection layers include dielectric multilayer films, intermediate refractive index media, and moth-eye structures in which the refractive index changes gradually. Among these, dielectric multilayer films are preferred from the standpoint of optical efficiency and productivity. Anti-reflection layers are obtained by alternately stacking dielectric films, just like reflective layers.

<Optical filter>
It is preferable that the optical filter of the present invention, having the above-mentioned configuration, satisfies all of the following spectral characteristics (iii-1) to (iii-7).
(iii-1) Average transmittance T _{440-490 (0 deg) AVE} in the spectral transmittance curve with a wavelength of 440 to 490 nm and an incident angle of 0 degrees is 85% or more. (iii-2) Average transmittance T _{440-490 (30 deg) AVE} in the spectral transmittance curve with a wavelength of 440 to 490 nm and an incident angle of 30 degrees is 85% or more. (iii-3) Average transmittance T _{500-570 (0 deg)} AVE in the spectral transmittance curve with a wavelength of 500 to 570 nm and an incident angle of 0 degrees is 90% or more. (iii-4) Average transmittance T _{500-570 (30 deg) AVE} in the spectral transmittance curve with a wavelength of 500 to 570 nm and an incident angle of 30 degrees is 90% or more. (iii-5) Maximum transmittance T in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 0 degrees. (iii-6) The maximum transmittance T _{700-850 (0 deg) MAX} in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 30 degrees is 1% or less. (iii-7) The maximum transmittance T _{700-850 (60 deg) MAX} in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 60 degrees is 1% or less.

By satisfying the spectral characteristics (iii-1) to (iii-4), an optical filter that is excellent in transmittance in the visible light region, particularly in blue light, even for light with a high angle of incidence can be obtained.
The spectral characteristics (iii-1) and (iii-2) are preferably 86% or more.
The spectral characteristics (iii-3) and (iii-4) are preferably 92% or more.

By satisfying the spectral characteristics (iii-5) to (iii-7), an optical filter that does not leak light even at a high incident angle and has high near-infrared light blocking properties can be obtained.
The spectral characteristic (iii-5) is preferably 2% or less.
The spectral characteristic (iii-6) is preferably 0.7% or less.
The spectral characteristic (iii-7) is preferably 0.8% or less.

The filter may also include other components (layers) that provide absorption by inorganic particles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic particles include ITO (indium tin oxide), ATO (antimony-doped tin oxide), cesium tungstate, lanthanum boride, etc. ITO particles and cesium tungstate particles have high visible light transmittance and light absorption over a wide range of infrared wavelengths exceeding 1200 nm, so they can be used when blocking such infrared light is required.

When this filter is used in an imaging device such as a digital still camera, for example, it can provide an imaging device with excellent color reproducibility. An imaging device using this filter includes a solid-state imaging element, an imaging lens, and this filter. This filter can be used, for example, by being placed 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.

Next, the present invention will be described more specifically with reference to examples.
The spectral characteristics were measured using an ultraviolet-visible spectrophotometer (UH-4150, manufactured by Hitachi High-Technologies Corporation).
In addition, unless the angle of incidence is specifically stated, the spectral characteristics are values measured at an angle of incidence of 0 degrees (perpendicular to the optical filter).

The dyes used in each example are as follows:
Compounds 1 to 9 (cyanine compounds): were synthesized with reference to the synthesis method described in Dyes and Pigments 73 (2007) pp. 344-352.
Compound 10 (squarylium compound): Synthesized with reference to WO 2014/088063.
Compound 11 (squarylium compound): Synthesized with reference to JP 2017-110209 A.

<Example 1-1: Spectral properties of NIR dye in resin>
NIR dye compound 1 (7.5% by mass) and polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Co., Ltd.) diluted with an organic solvent (cyclohexanone) were mixed to thoroughly dissolve the polyimide solution and dye.
The obtained dye solution was applied to a glass substrate (alkali glass, Shotto D263) by spin coating, and the organic solvent was removed by sufficient heating to form a dye-containing resin thin film (coated film) having a thickness of 1 μm.
The thin film thus obtained was subjected to measurement of transmission spectroscopy in the wavelength range of 350 nm to 1200 nm at an incident direction of 0 degrees and reflection spectroscopy in the incident direction of 5 degrees.
The transmittance was expressed as the internal transmittance represented by the following formula.
Internal transmittance (%)={measured transmittance _{(0 deg)} /(100-reflectance _{(5 deg)} )}×100
The absorbance is a value calculated from the internal transmittance using the following formula.
Absorbance = -log10 (internal transmittance/100)

<Examples 1-2 to 1-18>
A dye-containing resin thin film was prepared in the same manner as in Example 1-1, except that the NIR dye compound 1 was replaced with the NIR dye shown in the table below in the amount shown in the table below, one of the resins shown below was used instead of the polyimide resin, and the thickness of the thin film was set to the value shown in the table below, and the transmission spectrum was measured.
Polyester resin: Osaka Gas Chemicals Cycloolefin resin: JSR ARTON F4520
The results are shown in the table below.

Note that Examples 1-10 to 1-14 are examples, and Examples 1-1 to 1-9 and 1-15 to 1-18 are comparative examples.

IR50 width (nm): absolute value of difference between IR50a and IR50b IR30 width (nm): absolute value of difference between IR30a and IR30b

The results of Examples 1-10 to 1-14 show that the external salt type cyanine dye exhibits a wide range of near-infrared light absorption characteristics while maintaining high transmittance of blue light in an alicyclic compound polymer.

<Comparison of resin spectroscopy and solution spectroscopy>
<Examples 2-1 to 2-7: Solution spectroscopy>
The NIR dyes shown in the table below were dissolved in dichloromethane, and the solution spectroscopy was measured at wavelengths of 350 nm to 1200 nm. The spectral characteristics calculated so that the transmittance of the maximum absorption wavelength was 10% are shown in the table below.

<Examples 2-8 to 2-14: Resin Spectroscopy>
The spectral characteristics calculated from the transmission and reflection spectroscopy of the thin films produced in Examples 1-10 to 1-16 so that the transmittance at the maximum absorption wavelength was 10% are shown in the table below.

The IR50 and IR30 bands were compared for solution and resin spectra with the same NIR dye.
5 shows the solution spectrum of Example 2-4 and the resin spectrum of Example 2-11 for Compound 6. The solid line shows the resin spectrum, and the dashed line shows the solution spectrum.

IR30 width _(DIC) (nm): absolute value of difference between IR30a _(DIC) and IR30b _(DIC) IR30 width _(PO) (nm): absolute value of difference between IR30a _(PO) and IR30b _(PO) IR50 width _(DIC) (nm): absolute value of difference between IR50a _(DIC) and IR50b _(DIC) IR50 width _(PO) (nm): absolute value of difference between IR50a _(PO) and IR50b _(PO) IR30 width (relative to dichloromethane): ratio of IR30 width ( _{PO ) to IR30 width (DIC} ) IR50 width (relative to dichloromethane): ratio of IR50 width _(PO ) to IR50 width _(DIC)

Examples 2-1 to 2-7 are reference examples, Examples 2-8 to 2-12 are working examples, and Examples 2-13 to 2-14 are comparative examples.

From the above results, in Examples 2-8 to 2-12 in which an external salt type cyanine dye was used as the NIR dye, the IR30 width and the IR50 width were significantly wider in the resin than in the solution.
That is, the absorption spectrum was broadened in the resin.

<Example 3-1: Spectral characteristics of optical filters>
Compound 11, an NIR dye, was added to polyimide resin (C-3G30G manufactured by Mitsubishi Gas Chemical Company) in an amount of 5.25% by mass relative to the resin, and cyclohexanone was further added as a solvent to thoroughly dissolve the dye (dye solution 1).
Compound 6, an NIR dye, was added to a cycloolefin resin (ARTON resin F4520 manufactured by JSR Corporation) in an amount of 2% by mass relative to the resin, and cyclohexanone was further added as a solvent to thoroughly dissolve the dye (dye solution 2).
An ultraviolet/infrared cut multilayer film having a transmission band of 400 nm to 700 nm was deposited on a glass substrate (alkali glass, Shotto D263). A dye solution 1 was spin-coated on the surface opposite the ultraviolet/infrared cut multilayer film to form a 1 μm-thick resin film 1. A dye solution 2 was spin-coated on top of the resin film 1 to form a 1.6 μm-thick resin film 2. A dielectric multilayer film (anti-reflection film) composed of _SiO2 and _TiO2 was deposited by deposition on the two-layer resin film to produce an optical filter 3-1.

<Example 3-2>
An optical filter 3-2 was produced in the same manner as in Example 3-1, except that the content of compound 11 in the production of resin film 1 was 5.5% by mass, and resin film 2 was not applied.

For each optical filter, the transmission spectrum was measured in the wavelength range of 350 nm to 1200 nm at incident directions of 0 deg, 30 deg, and 60 deg using a spectrophotometer. The results are shown in the table below.
FIG. 6 shows the spectral transmittance curve of the optical filter 3-1.

Example 3-1 is an embodiment, and Example 3-2 is a comparative example.

From the above results, it can be seen that the optical filter of Example 3-1 has high transmittance in the visible light region of 440 to 490 nm and 500 to 570 nm at both incidence angles of 0 degrees and 30 degrees, has excellent light blocking properties in the infrared light region above 700 nm, and has low maximum transmittance even at oblique incidence angles of 30 degrees and 60 degrees in the wavelength region of 700 to 850 nm, thereby reducing light leakage.

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. 2020-128621) filed on July 29, 2020, the contents of which are incorporated herein by reference.

The optical filter of the present invention has good near-infrared light shielding properties, with good near-infrared light shielding properties and good visible light transmittance, particularly blue light transmittance, while suppressing deterioration of near-infrared light shielding properties, particularly at high angles of incidence. It is useful for applications in information acquisition devices, such as cameras and sensors for transport aircraft, which have become increasingly high-performance in recent years.

1A, 1B, 1C, 1D...optical filter, 10...substrate, 11...support, 12...resin film, 30...dielectric multilayer film

Claims (12)

An optical filter comprising a substrate and a dielectric multilayer film laminated as an outermost layer on at least one main surface side of the substrate,
the substrate includes a resin film containing a dye (A) that is a near-infrared absorbing dye and a resin,
The dye (A) satisfies all of the following spectral characteristics (i-1) to (i-4) in a spectral transmittance curve of a coating film obtained by dissolving the dye (A) in the resin and coating the coating film on an alkali glass plate,
(i-1) When the shortest wavelength at which the transmittance is 30% in the wavelength range of 600 to 800 nm is defined as IR30a, and the longest wavelength at which the transmittance is 30% in the wavelength range of 700 to 1200 nm is defined as IR30b,
The absolute value of the difference between IR30a and IR30b is 170 nm or more (i-2). When IR50a is the shortest wavelength at which the transmittance is 50% in the wavelength range of 600 to 800 nm, and IR50b is the longest wavelength at which the transmittance is 50% in the wavelength range of 700 to 1200 nm,
The absolute value of the difference between IR50a and IR50b is 200 nm or more. (i-3) The relationship between the absorbance A ₄₄₀ at a wavelength of 440 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₄₀ /A ₇₀₀ ≦0.14.
(i-4) The relationship between the absorbance A ₄₉₀ at a wavelength of 490 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₄₉₀ /A ₇₀₀ ≦0.10.
The optical filter, wherein the dye (A) contains at least one of a compound represented by the following formula (A1) and a compound represented by the following formula (A2):

In the formulae (A1) and (A2), the symbols are as follows:
R ¹⁰¹ , R ¹⁰⁶ , and R ¹⁰⁷ each independently represent a hydrogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹²¹ , R ¹²⁸ , and R ¹²⁹ each independently represent a hydrogen atom, a halogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. R ¹⁰² to R ¹⁰⁵ , R ¹⁰⁸ , R ¹⁰⁹ , R ¹²² to R ¹²⁷ , R ¹³⁰ , and R ¹³¹ each independently represent a hydrogen atom, an alkyl group or alkoxy group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms. R ¹¹⁰ to ¹¹⁴ and R ¹³² to ¹³⁶ each independently represent a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 15 carbon atoms.
X ⁻ represents a monovalent anion.
n1 and n2 each independently represent 0 or 1. A hydrogen atom bonded to the carbocycle containing -(CH ₂ ) _n1 - and the carbocycle containing -(CH ₂ ) _n2 - may be substituted with a halogen atom, an alkyl group having 1 to 15 carbon atoms which may have a substituent, or an aryl group having 5 to 20 carbon atoms. 2. The optical filter according to claim 1, wherein the dye (A) further satisfies the following spectral characteristic (i-5) in a spectral transmittance curve of the coating film.
(i-5) the product of the content of the dye (A) in the coating film and the thickness of the coating film is 20 (mass% μm) or less 3. The optical filter according to claim 1, wherein the dye (A) further satisfies the following spectral characteristic (i-6) in a spectral transmittance curve of the coating film.
(i-6) The relationship between the absorbance A ₅₇₀ at a wavelength of 570 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₅₇₀ /A ₇₀₀ ≦0.11. 4. The optical filter according to claim 1, wherein the dye (A) further satisfies the following spectral characteristic (i-7) in a spectral transmittance curve of the coating film.
(i-7) The relationship between the absorbance A ₆₃₀ at a wavelength of 630 nm and the absorbance A ₇₀₀ at a wavelength of 700 nm is A ₆₃₀ /A ₇₀₀ ≦0.12. 5. The optical filter according to claim 1, wherein the dye (A) further satisfies the following spectral characteristic (i-8) in a spectral transmittance curve of the coating film.
(i-8) The average internal transmittance T _700-800 in the spectral transmittance curve for wavelengths of 700 to 800 nm is 2 to 25%. In the spectral characteristic (i-1), the absolute value of the difference between IR30a and IR30b is 190 nm or more;
In the spectral characteristic (i-2), the absolute value of the difference between IR50a and IR50b is 230 nm or more;
In the spectroscopic characteristic (i-3), A ₄₄₀ /A ₇₀₀ ≦0.11;
In the spectroscopic characteristic (i-4), A ₄₉₀ /A ₇₀₀ ≦0.07;
The optical filter according to any one of claims 1 to 5. The optical filter according to any one of claims 1 to 6, wherein the resin film has a thickness of 10 μm or less. The optical filter according to any one of claims 1 to 7, wherein the substrate includes a support and the resin film, the resin film is laminated on at least one main surface of the support, and the thickness of the resin film is 5 μm or less. 9. The optical filter according to claim 1, wherein the dye (A) satisfies the following properties (ii-1) and (ii-2):
In the spectral transmittance curve measured by dissolving the dye (A) in dichloromethane so that the transmittance at the maximum absorption wavelength is 10%,
The shortest wavelength at which the transmittance is 30% in the wavelength range of 600 to 900 nm is designated IR30a _(DIC) , the longest wavelength at which the transmittance is 30% is designated IR30b _(DIC) , the shortest wavelength at which the transmittance is 50% is designated IR50a _(DIC) , and the longest wavelength at which the transmittance is 50% is designated IR50b _(DIC) ,
The dye (A) is dissolved in the resin and applied onto an alkali glass plate so that the transmittance at the maximum absorption wavelength is 10%, and the spectral transmittance curve of the coating film is
In the wavelength range of 600 to 900 nm, the shortest wavelength at which the transmittance is 30% is defined as IR30a _(PO) , the longest wavelength at which the transmittance is 30% is defined as IR30b _(PO) , the shortest wavelength at which the transmittance is 50% is defined as IR50a _(PO) , and the longest wavelength at which the transmittance is 50% is defined as IR50b _(PO) ,
(ii-1) The absolute value of the difference between IR30a _(PO) and IR30b _(PO) is 3 times or more the absolute value of the difference between IR30a _(DIC) and IR30b _(DIC). (ii-2) The absolute value of the difference between IR50a _(PO) and IR50b _(PO) is 2.8 times or more the absolute value of the difference between IR50a _(DIC) and IR50b _(DIC) . The optical filter according to any one of claims 1 to 9, wherein the resin is a polymer composed of an alicyclic compound. 11. The optical filter according to claim 1 , wherein the resin film further contains at least one dye (B) selected from a squarylium dye, a phthalocyanine dye, and a diimmonium dye. The optical filter according to any one of claims 1 to 11 , which satisfies all of the following spectral characteristics (iii-1) to (iii-7):
(iii-1) Average transmittance T _{440-490 (0 deg) AVE} in the spectral transmittance curve with a wavelength of 440 to 490 nm and an incident angle of 0 degrees is 85% or more. (iii-2) Average transmittance T _{440-490 (30 deg) AVE} in the spectral transmittance curve with a wavelength of 440 to 490 nm and an incident angle of 30 degrees is 85% or more. (iii-3) Average transmittance T _{500-570 (0 deg)} AVE in the spectral transmittance curve with a wavelength of 500 to 570 nm and an incident angle of 0 degrees is 90% or more. (iii-4) Average transmittance T _{500-570 (30 deg) AVE} in the spectral transmittance curve with a wavelength of 500 to 570 nm and an incident angle of 30 degrees is 90% or more. (iii-5) Maximum transmittance T in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 0 degrees. (iii-6) The maximum transmittance T _{700-850 (0 deg) MAX} in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 30 degrees is 1% or less. (iii-7) The maximum transmittance T _{700-850 (60 deg) MAX} in the spectral transmittance curve with a wavelength of 700 to 850 nm and an incident angle of 60 degrees is 1% or less.

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