Optical filter

Abstract

The present invention relates to an optical filter comprising a near infrared ray absorbing glass, a resin film, a dielectric multilayer film (I), and a dielectric multilayer film (II), wherein the resin film includes a pigment having a maximum absorption wavelength in 680-870 nm, and the optical filter satisfies all of specific spectral characteristics (i-1) to (i-6) and the following spectral characteristics (i-7) and (i-8). (i-7) The average reflectance at an incidence angle of 40 degrees and a wavelength of 700-800 nm is 5.5% or less. (i-8) The average reflectance at an incidence angle of 40 degrees and a wavelength of 800-1,200 nm is 10% or greater.

Description

[Technical Field]

[0001] This invention relates to an optical filter that transmits visible light and blocks near-infrared light. [Background technology]

[0002] In imaging devices using solid-state image sensors, optical filters are used that transmit visible light (hereinafter also referred to as "visible light") and block near-infrared wavelength light (hereinafter also referred to as "near-infrared light") in order to reproduce colors well and obtain sharp images.

[0003] Such optical filters can take various forms, such as reflective filters that alternately stack dielectric thin films with different refractive indices on one or both sides of a transparent substrate (dielectric multilayer film) and reflect the light to be blocked by utilizing light interference.

[0004] Patent documents 1 and 2 describe optical filters having a dielectric multilayer film and an absorbing layer containing a dye. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2020 / 050177 [Patent Document 2] International Publication No. 2020 / 004641 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Most of the light that passes through the optical filter enters the sensor, but some of the light is reflected from the sensor surface, further reflected on the dielectric multilayer film on the back side of the optical filter, and re-enters the sensor, causing a phenomenon known as stray light, where light is generated outside the intended optical path. This stray light caused by repeated reflections between the optical filter and the sensor can cause flare and ghosting in solid-state image sensors, potentially degrading image quality. With the increasing demand for higher image quality in camera modules in recent years, there is a need for optical filters that are less prone to causing flare and ghosting. In particular, since the 700-800 nm wavelength range is highly sensitive to sensors, suppression of flare and ghosting in this wavelength range is desirable.

[0007] Furthermore, since the optical thickness of dielectric multilayer films changes depending on the angle of incidence of light, the reflective properties can change, and the above-mentioned flare and ghosting are more likely to occur at higher angles of incidence. In particular, with the recent trend towards lower-profile camera modules, use under high angle of incidence conditions is anticipated, so there is a need for optical filters that are less affected by the angle of incidence.

[0008] The present invention aims to provide an optical filter that exhibits excellent transmittance in the visible light region and shielding in the near-infrared light region, even at high incidence angles, while suppressing flare and ghosting. [Means for solving the problem]

[0009] The present invention provides an optical filter and the like having the following configuration. [1] An optical filter comprising a substrate, a dielectric multilayer film (I) laminated as the outermost layer on one main surface side of the substrate, and a dielectric multilayer film (II) laminated as the outermost layer on the other main surface side of the substrate, The substrate comprises near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass. The resin film comprises a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-8). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T in the wavelength range of 440 to 600 nm 440-600(0deg)AVE is 86% or more (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR50 at which the transmittance becomes 50% in the wavelength range of 550 to 750 nm (0deg)T and the wavelength IR50 at which the transmittance becomes 50% in the wavelength range of 550 to 750 nm in the spectral transmittance curve at an incident angle of 40 degrees (40deg)T The absolute value of the difference between them is 6 nm or less (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T in the wavelength range of 700 to 800 nm 700-800(0deg)AVE is 1% or less (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T in the wavelength range of 8 to 1200 nm 800-1200(0deg)AVE is 3% or less (i-5) When the dielectric multilayer film (I) side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI in the wavelength range of 440 to 600 nm 440-600(5deg)AVE is 4% or less (i-6) When the dielectric multilayer film (I) side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI in the wavelength range of 800 to 1200 nm 800-1200(5deg)AVE is 95% or more (i-7) When the dielectric multilayer film (II) side is the incident direction, in the spectral reflectance curve at an incident angle of 40 degrees, the average reflectance RII in the wavelength range of 700 to 800 nm 700-800(40deg)AVE is 5.5% or less (i-8) When the dielectric multilayer film (II) side is the incident direction, in the spectral reflectance curve at an incident angle of 40 degrees, the average reflectance RII in the wavelength range of 800 to 1200 nm 800-1200(40deg)AVE is 10% or more

Advantages of the Invention

[0010] According to the present invention, even at a high incident angle, an optical filter excellent in visible light transmittance and near-infrared light shielding property and suppressing flare and ghost can be provided.

Brief Description of the Drawings

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of an optical filter according to one embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing another example of an optical filter according to one embodiment. [Figure 3] Figure 3 illustrates the mechanism of repetitive reflection generation between the sensor and the optical filter. [Figure 4] Figure 4 shows the spectral transmittance curves of the resin film in Example 1-1 and the resin film in Example 1-2. [Figure 5] Figure 5 shows the spectral reflectance curves of the dielectric multilayer film (II) of Example 3-3 and the dielectric multilayer film (II) of Example 3-4. [Figure 6] Figure 6 shows the spectral transmittance curves of the optical filter of Example 4-1 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side. [Figure 7] Figure 7 shows the spectral reflectance curve of the optical filter of Example 4-1 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side. [Figure 8] Figure 8 shows the spectral transmittance curves of the optical filter of Example 4-2 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side. [Figure 9] Figure 9 shows the spectral reflectance curve of the optical filter of Example 4-2 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below. In this specification, near-infrared absorbing dyes may be abbreviated as "NIR dyes," and ultraviolet absorbing dyes may be abbreviated as "UV dyes." In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. A dye consisting of compound (I) is also referred to as dye (I), and the same applies to other dyes. Furthermore, the group represented by formula (I) is also referred to as group (I), and the same applies to groups represented by other formulas.

[0013] In this specification, internal transmittance is defined by the formula {measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))} × 100, which is the transmittance obtained by subtracting the effect of interfacial reflection from the measured transmittance. In this specification, the spectral transmission of a substrate and the transmission of a resin film, including cases where a dye is contained in the resin, refers to "internal transmission" even when the term "transmission" is used. On the other hand, the transmission of a dielectric multilayer film and the transmission of an optical filter having a dielectric multilayer film are measured transmission values.

[0014] In this specification, for a particular wavelength range, a transmittance of, for example, 90% or more means that the transmittance does not fall below 90% across the entire wavelength range, i.e., the minimum transmittance in that wavelength range is 90% or more. Similarly, for a particular wavelength range, a transmittance of, for example, 1% or less means that the transmittance does not exceed 1% across the entire wavelength range, i.e., the maximum transmittance in that wavelength range is 1% or less. The same applies to internal transmittance. The average transmittance and average internal transmittance in a particular wavelength range are the arithmetic mean of the transmittance and internal transmittance for every 1 nm in that wavelength range. The spectral characteristics can be measured using a UV-Vis spectrophotometer. In this specification, the symbol "~" used to indicate a numerical range includes both upper and lower limits.

[0015] <Optical filters> An optical filter according to one embodiment of the present invention (hereinafter also referred to as "this filter") comprises a substrate, a dielectric multilayer film 1 laminated as the outermost layer on one main surface side of the substrate, and a dielectric multilayer film 2 laminated as the outermost layer on the other main surface side of the substrate. Here, the substrate comprises near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass. Furthermore, the resin film comprises a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin. The reflective properties of the dielectric multilayer film, combined with the absorption properties of the substrate containing near-infrared absorbing glass and near-infrared absorbing dye, enable the overall optical filter to achieve excellent transmittance in the visible light region and excellent shielding in the near-infrared light region.

[0016] An example of the configuration of this filter will be explained using the drawings. Figures 1 and 2 are schematic cross-sectional views showing an example of an optical filter according to one embodiment.

[0017] The optical filter 1A shown in Figure 1 is an example in which a dielectric multilayer film 20I is present on one main surface side of a substrate 10 having near-infrared absorbing glass 11 and a resin film 12, i.e., on the near-infrared absorbing glass 11 in Figure 1, and on the other main surface side, i.e., on the resin film 12 in Figure 1, a dielectric multilayer film 20II is present. Note that "having a specific layer on the main surface side of the substrate" is not limited to cases where the layer is in contact with the main surface of the substrate, but also includes cases where another functional layer is provided between the substrate and the layer.

[0018] The optical filter 1B shown in Figure 2 is an example in which the substrate 10 has resin films 12A and 12B on both main surfaces of the near-infrared absorbing glass 11, and dielectric multilayer films 20I and 20II on both main surfaces of the substrate 10.

[0019] The optical filter of the present invention satisfies all of the following spectral characteristics (i-1) to (i-8). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 440 to 600 nm. 440-600(0deg)AVE over 86% (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR50 is such that the transmittance is 50% in the range of wavelengths 550 to 750 nm. (0deg)T And, in the spectral transmittance curve at an incident angle of 40 degrees, the wavelength IR50 has a transmittance of 50% in the wavelength range of 550 to 750 nm. (40deg)T The absolute value of the difference is 6 nm or less. (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 700-800 nm. 700-800(0deg)AVE less than 1% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 800 to 1200 nm. 800-1200(0deg)AVEless than 3% (i-5) When the dielectric multilayer film (I) side is the incident direction, the spectral reflectance curve at an incident angle of 5 degrees shows the average reflectance RI at wavelengths of 440 to 600 nm. 440-600(5deg)AVE less than 4% (i-6) When the dielectric multilayer film (I) side is the incident direction, the average reflectance RI at wavelengths of 800 to 1200 nm is shown in the spectral reflectance curve at an incident angle of 5 degrees. 800-1200(5deg)AVE over 95% (i-7) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 700-800 nm. 700-800(40deg)AVE less than 5.5% (i-8) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 800 to 1200 nm. 800-1200(40deg)AVE over 10%

[0020] As shown in characteristic (i-6), the optical filter of the present invention reflects near-infrared light on one main surface side of the optical filter, i.e., the dielectric multilayer film (I) side, while suppressing the reflection of near-infrared light on the other main surface side, i.e., the dielectric multilayer film (II) side, as shown in characteristic (i-7). As shown in Figure 3, incident light L0 passes through the optical filter 1A, and a portion is reflected on one of the main surfaces Sa of the sensor S (reflected light L1). The reflected light L1 is reflected on the back surface of the optical filter, i.e., the main surface 20IIb of the dielectric multilayer film 20II (reflected light L2), and this reflected light L2 re-enters the sensor S, which can cause flare and ghosting. By mounting the optical filter so that the main surface side that suppresses the reflection of near-infrared light, i.e., the dielectric multilayer film (II) side, faces the sensor, back surface reflection of the optical filter that causes flare and ghosting can be suppressed. The optical filter of the present invention also exhibits excellent transmittance in the visible light region and shielding in the near-infrared light region, even at high incidence angles, as shown in characteristics (i-1) to (i-4). The following details each characteristic.

[0021] Satisfying spectral characteristics (i-1) means that the material exhibits excellent transmittance in the visible light region. Average transmittance T 440-600(0deg)AVE Preferably, it is 88% or more, more preferably 90% or more. To satisfy the spectral characteristics (i-1), for example, a dielectric multilayer film with low visible light reflectivity can be used.

[0022] Satisfying spectral characteristic (i-2) means that the spectral transmittance curve in the 550-750 nm region is less likely to shift even at high incidence angles. The absolute value in the spectral characteristic (i-2) is preferably 3 to 5 nm, more preferably 3 to 4 nm. To satisfy the spectral characteristics (i-2), for example, the wavelength region of 600-700 nm can be shielded by the absorption characteristics of the NIR dye. However, when utilizing the absorption characteristics of the dye, the transmittance tends to decrease because the dye also absorbs the visible light region of 440-600 nm. Therefore, it is preferable to select a dye from among the dyes having the squarylium structure described later, according to the desired shielding band.

[0023] Meeting the spectral characteristics (i-3) means that the material exhibits excellent light-shielding properties in the near-infrared region, specifically in the 700-800 nm range. Average transmittance T 700-800(0deg)AVE The amount is preferably 0.3% or less, and more preferably 0.15% or less. To satisfy the spectral characteristics (i-3), for example, a dye that can absorb light in the 700-800 nm range can be used.

[0024] Meeting the spectral characteristics (i-4) means that the material exhibits excellent light-shielding properties in the near-infrared region, specifically in the 800-1200 nm range. Average transmittance T 800-1200(0deg)AVE The amount is preferably 1% or less, and more preferably 0.5% or less. To satisfy the spectral characteristics (i-4), for example, one could increase the near-infrared reflectance of one of the dielectric multilayer films or use near-infrared absorbing glass.

[0025] Satisfying the spectral characteristics (i-5) means that the material has excellent transmittance in the visible light region. Average reflectance RI 440-600(5deg)AVE The amount is preferably 3% or less, and more preferably 1.5% or less. To satisfy the spectral characteristics (i-5), for example, one can design the dielectric multilayer film (I) to have a low visible light reflectance.

[0026] Meeting the spectral characteristics (i-6) means that the material exhibits excellent light-shielding properties in the near-infrared region, specifically in the 800-1200 nm range. Average reflectance RI 800-1200(5deg)AVE The percentage is preferably 97% or higher, and more preferably 98% or higher. To satisfy the spectral characteristics (i-6), for example, one can design the dielectric multilayer film (I) to have a high near-infrared reflectance.

[0027] Satisfying spectral characteristics (i-7) means that even at high incidence angles, the reflectance in the near-infrared region of 700-800 nm is low. Average reflectance RII 700-800(40deg)AVE The amount is preferably 3% or less, and more preferably 2% or less. To satisfy the spectral characteristics (i-7), for example, one can design the dielectric multilayer film (II) to have a low reflectivity in the 700-800 nm range.

[0028] Spectral characteristics (i-8) refer to the range in the near-infrared region where reflection of 800-1200 nm is acceptable at high incidence angles. Average reflectance RII 800-1200(40deg)AVE The amount is preferably 20% or more, and more preferably 30% or more. To satisfy the spectral characteristics (i-8), for example, one can design the dielectric multilayer film (II) to have a high reflectivity in the 800-1200 nm range.

[0029] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 50 degrees shows the average reflectance RII at wavelengths of 700-800 nm. 700-800(50deg)AVE 8% or less (i-10) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 50 degrees shows the average reflectance RII at wavelengths of 800 to 1200 nm. 800-1200(50deg)AVE over 10%

[0030] Satisfying spectral characteristics (i-9) means that even at higher incidence angles, the reflectance in the near-infrared region between 700 and 800 nm is low. Average reflectance RII 700-800(50deg)AVE The amount is preferably 5% or less, and more preferably 4% or less.

[0031] The spectral characteristic (i-10) refers to the range in the near-infrared region where reflection of 800-1200 nm is acceptable at higher incidence angles. Average reflectance RII 800-1200(50deg)AVE The amount is preferably 20% or more, and more preferably 30% or more.

[0032] The optical filter of the present invention preferably further satisfies the following spectral characteristics (i-12). (i-12) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength at which the transmittance is 50% in the range of 550 to 750 nm is defined as IR50. (0deg)T year, When the dielectric multilayer film (I) side is the incident direction, the wavelength at which the reflectance is 50% in the spectral reflectance curve at an incident angle of 5 degrees, in the wavelength range of 550 to 750 nm, is defined as IR50. (5deg)R In that case, IR50 (0deg)T and IR50 (5deg)R The absolute value of the difference is 85 nm or more.

[0033] The spectral characteristics (i-12) define the relationship between transmittance and reflectance when incident from the dielectric multilayer film (I) side, and the wavelength position where the transmittance is 50% (IR50 (0deg)T ) to the wavelength position where the reflectance becomes 50% (IR50(5deg)R This means that the wavelengths are sufficiently far apart on the longer wavelength side. As shown in Figure 3, the incident light L0 passes through the optical filter 1A, and a portion of it is reflected off one of the main surfaces Sa of the sensor S (reflected light L3). The reflected light L3 is then re-incident into the optical filter 1A and reflected off the inner surface 20Ib of the dielectric multilayer film 20I (reflected light L4). The re-incidentation of this reflected light L4 into the sensor S can also generate flare and ghosting, similar to the reflected light L2. By satisfying the spectral characteristics (i-12), internal reflections of the dielectric multilayer film 20I at wavelengths of 550-750 nm are suppressed, thereby reducing flare and ghosting. Also, IR50 (5deg)R Because the light-blocking properties in the 700-800nm ​​range are sufficiently separated from the longer wavelength side, the light-blocking properties can be compensated for more by the absorption properties of the near-infrared absorbing dye than by the reflection properties.

[0034] IR50 (0deg)T The wavelength is preferably in the range of 615 to 670 nm. IR50 (5deg)R The wavelength is preferably in the range of 700 to 750 nm. IR50 (0deg)T and IR50 (5deg)R The absolute value of the difference is more preferably 85 nm or more.

[0035] <Dielectric multilayer film> In this filter, the dielectric multilayer film is laminated as the outermost layer on both main surfaces of the substrate. The dielectric multilayer film (I) is laminated on one main surface side of the substrate, and the dielectric multilayer film (II) is laminated on the other main surface side of the substrate.

[0036] The dielectric multilayer film (I) preferably satisfies all of the following spectral characteristics (vI-1) to (vI-4). (vI-1) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI at wavelengths of 440-600 nm 440-600(5deg)AVE less than 10% (vI-2) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI at wavelengths of 800-1200 nm is 800-1200(5deg)AVE over 95% (vI-3) In the spectral reflectance curve at an incident angle of 40 degrees, the average reflectance RI at wavelengths of 440-600 nm 440-600(40deg)AVE less than 11% (vI-4) In the spectral reflectance curve at an incident angle of 40 degrees, the average reflectance RI at wavelengths of 800-1200 nm 800-1200(40deg)AVE over 88%

[0037] Satisfying the spectral characteristics (vI-1) means that the material has excellent transmittance in the visible light region. Average reflectance RI 440-600(5deg)AVE Preferably, it is 8% or less, more preferably 6% or less.

[0038] Satisfying spectral characteristics (vI-2) means that the material exhibits excellent reflectivity of near-infrared light in the 800-1200 nm range. Average reflectance RI 800-1200(5deg)AVE The percentage is preferably 96% or more, and more preferably 98% or more.

[0039] Satisfying the spectral characteristics (vI-3) means that the light exhibits excellent transmittance in the visible light region, even at high incidence angles. Average reflectance RI 440-600(40deg)AVE The amount is preferably 10% or less, and more preferably 9% or less.

[0040] Satisfying spectral characteristics (vI-4) means that the reflectivity of near-infrared light in the 800-1200 nm range is excellent, even at high incidence angles. Average reflectance RI 800-1200(40deg)AVE Preferably, it is 89% or more, more preferably 90% or more.

[0041] By designing the dielectric multilayer film (I) to satisfy spectral characteristics (vI-1) to (vI-4), the optical filter is more likely to satisfy spectral characteristics (i-5) and (i-6). As described above, the dielectric multilayer film (I) functions primarily as a reflective film that reflects near-infrared light.

[0042] The dielectric multilayer film (II) preferably satisfies all of the following spectral characteristics (v-II-1) to (v-II-2). (v-II-1) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII is observed at wavelengths of 700-800 nm. 700-800(5deg)MAX 8% or less (v-II-2) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII at wavelengths of 700-800 nm 700-800(5deg)AVE less than 6%

[0043] Satisfying spectral characteristics (v-II-1) and (v-II-2) means that the reflectance at wavelengths of 700-800 nm is low. By designing the dielectric multilayer film (II) to have low reflectance at wavelengths of 700-800 nm, the optical filter is more likely to satisfy spectral characteristics (i-7). Maximum reflectance RII 700-800(5deg)MAX The content is preferably 7.5% or less, and more preferably 6% or less. Average reflectance RII 700-800(5deg)AVE The amount is preferably 5.5% or less, and more preferably 5% or less.

[0044] The dielectric multilayer film (II) preferably further satisfies the following spectral characteristics (v-II-5). (v-II-5) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is calculated for wavelengths of 800-1200 nm. 800-1200(5deg)AVE over 20%

[0045] Satisfying the spectral characteristics (v-II-5) means that the reflectance is high in the wavelength range of 800 to 1200 nm. Average reflectance RII 800-1200(5deg)AVE The percentage is preferably 27% or more, more preferably 25% or more.

[0046] The dielectric multilayer film (II) preferably further satisfies the following spectral characteristics (v-II-6). (v-II-6) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is found at wavelengths of 440-600 nm. 440-600(5deg)AVE less than 6%

[0047] Satisfying the spectral characteristics (v-II-6) means that the material exhibits excellent transmittance in the visible light region. Average reflectance RII 440-600(5deg)AVE It is more preferable to have 5% or less.

[0048] The spectral characteristics of the dielectric multilayer films (I) and (II) described above are obtained by measuring the reflectance of each dielectric multilayer film deposited on a transparent glass substrate.

[0049] In this filter, dielectric multilayer film (I) is designed as a near-infrared light reflective layer (hereinafter also referred to as the NIR reflective layer), and dielectric multilayer film (II) is designed as a near-infrared light anti-reflection layer (hereinafter also referred to as the NIR anti-reflection layer).

[0050] The NIR reflective layer and the NIR anti-reflective layer are composed, for example, of a dielectric multilayer film in which dielectric films with different refractive indices are alternately stacked. Examples of dielectric films include low refractive index dielectric films (low refractive index films) and high refractive index dielectric films (high refractive index films), and it is preferable to stack these alternately.

[0051] The high refractive index film preferably has a refractive index of 1.6 or higher, and more preferably 2.2 to 2.5. Examples of materials for the high refractive index film include Ta2O5, TiO2, and Nb2O5. Of these, TiO2 is preferred in terms of film formation properties, reproducibility of refractive index, stability, etc.

[0052] The low refractive index film preferably has a refractive index of less than 1.6, and more preferably 1.4 to 1.5. Examples of materials for the low refractive index film include SiO2 and SiO2. x N y These are some examples. SiO2 is preferred in terms of reproducibility, stability, and cost-effectiveness in film formation.

[0053] As described above, in order to create a dielectric multilayer film with controlled reflection characteristics, one method is to combine several dielectric films with different spectral characteristics when transmitting and selecting the desired wavelength band.

[0054] The NIR reflective layer preferably has a total number of dielectric multilayer layers of 20 or more, more preferably 30 or more, and even more preferably 40 or more, and preferably 60 or fewer from the viewpoint of productivity and the ability to reduce substrate warping. Furthermore, the thickness of the NIR reflective layer is preferably 3 to 6 μm overall.

[0055] The NIR anti-reflective layer preferably has a total number of dielectric multilayer layers of 30 or fewer, more preferably 25 or fewer, even more preferably 20 or fewer, and also preferably 4 or more. Furthermore, the thickness of the NIR anti-reflective layer is preferably 0.1 to 2 μm overall.

[0056] For forming dielectric multilayer films, vacuum deposition processes such as CVD, sputtering, and vacuum evaporation, as well as wet deposition processes such as spraying and dipping, can be used.

[0057] A dielectric multilayer film may provide predetermined optical properties with a single layer (or a group of dielectric multilayer films), or with two or more layers. If there are two or more layers, each dielectric multilayer film may have the same or different configuration.

[0058] The dielectric multilayer film (I) and the dielectric multilayer film (II) may be laminated on either the main surface of the substrate, but it is generally preferable that the dielectric multilayer film (I) is laminated on the near-infrared absorbing glass side and the dielectric multilayer film (II) is laminated on the resin film side. Since the dielectric multilayer film (II), which functions as an anti-reflective layer, generally has fewer layers and less thickness than the dielectric multilayer film (I), which functions as a reflective layer, the stress on the resin film can be reduced. Lower stress on the resin film makes it less likely for wrinkles to occur in the resin film even when the resin softens under high temperature and high humidity, thus improving reliability.

[0059] Furthermore, when mounting the optical filter on the imaging device, the dielectric multilayer film (I), which is the NIR reflective layer, is placed on the lens side, and the dielectric multilayer film (II), which is the NIR anti-reflective layer, is placed on the sensor side. This configuration reduces repeated reflections between the sensor and the optical filter, thereby suppressing the occurrence of flare and ghosting.

[0060] <Base material> In the optical filter of the present invention, the substrate comprises near-infrared absorbing glass and a resin film. The resin film contains a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin, and is laminated on at least one main surface of the near-infrared absorbing glass. Thus, the substrate possesses both the absorption capacity of the near-infrared absorbing glass and the absorption capacity of the resin film containing the near-infrared absorbing dye (NIR1).

[0061] <Near-infrared absorbing glass> The near-infrared absorbing glass preferably satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Average internal transmittance T at wavelength 400~600nm 400-600AVE over 90% (iii-2) Average internal transmittance T at wavelengths of 700-800 nm 700-800AVE less than 40% (iii-3) Average internal transmittance T at wavelength 800~1200nm 800-1200AVE less than 40%

[0062] Meeting the spectral characteristics (iii-1) means that the material exhibits excellent transmittance in the visible light region of 400-600 nm. Average internal transmittance T 400-600AVE It is more preferably 92% or more, and even more preferably 95% or more.

[0063] Meeting the spectral characteristics (iii-2) means that the material exhibits excellent light-shielding properties in the near-infrared region of 700-800 nm. Average internal transmittance T 700-800AVE It is more preferably 30% or less, and even more preferably 25% or less.

[0064] Meeting the spectral characteristics (iii-3) means that the material exhibits excellent light-shielding properties in the near-infrared region of 800-1200 nm. Average internal transmittance T 800-1200AVE It is more preferably 30% or less, and even more preferably 25% or less.

[0065] The near-infrared absorbing glass is not limited to any glass that can obtain the above spectral characteristics, and examples include phthalate glass and phosphate glass that contain copper ions. Note that "phosphate glass" also includes silicate glass in which part of the glass skeleton is composed of SiO2.

[0066] Furthermore, as near-infrared absorbing glass, chemically strengthened glass obtained by exchanging alkali metal ions with small ionic radii (e.g., Li ions, Na ions) present on the main surface of the glass plate with alkali ions with larger ionic radii (e.g., Na ions or K ions for Li ions, and K ions for Na ions) by ion exchange at a temperature below the glass transition temperature may be used.

[0067] From the viewpoint of reducing the height of the camera module, the near-infrared absorbing glass preferably has a thickness of 0.5 mm or less, more preferably 0.3 mm or less, and from the viewpoint of element strength, preferably 0.15 mm or more.

[0068] <Resin film> The resin film preferably satisfies all of the following spectral characteristics (iv-1) to (iv-3). (iv-1) Average internal transmittance T at wavelength 440~600nm 440-600AVE over 90% (iv-2) Average internal transmittance T at wavelength 700~800nm 700-800AVE less than 50% (iv-3) In the spectral transmittance curve for wavelengths of 600-800 nm, the shortest wavelength at which the internal transmittance is 50% is IR50. (S) The longest wavelength is IR50 (L) In that case, IR50 (L) -IR50 (S)≥100nm

[0069] Meeting the spectral characteristics (iv-1) means that the material exhibits excellent visible light transmittance in the 440-600 nm range. Average internal transmittance T 440-600AVE It is more preferably 93% or more, and even more preferably 95% or more. To satisfy the spectral characteristics (iv-1), for example, one can use an NIR dye with low absorption characteristics in the visible light region, or reduce the amount of NIR dye.

[0070] Meeting the spectral characteristics (iv-2) means that the material has excellent light-shielding properties for near-infrared light with wavelengths of 700-800 nm. Average internal transmittance T 700-800AVE More preferably, it is 45% or less, and even more preferably 20% or less. To satisfy the spectral characteristics (iv-2), for example, an NIR dye with a maximum absorption wavelength of 700-800 nm can be used.

[0071] Satisfying spectral characteristics (iv-3) means that a wide range of near-infrared light in the wavelength range of 600-800 nm can be blocked. IR50 (L) -IR50 (S) The wavelength is more preferably 105 nm or greater, and even more preferably 110 nm or greater. Also IR50 (L) Preferably 720-810nm, IR50 (S) The wavelength is preferably in the range of 620-670 nm. To satisfy the spectral characteristics (iv-3), for example, two or more NIR dyes can be used.

[0072] The resin film in this invention contains a dye (NIR1) having a maximum absorption wavelength of 680-870 nm, and as shown in characteristic (iv-2) above, it exhibits excellent light shielding properties for near-infrared light in the 700-800 nm range, and as shown in characteristic (iv-3) above, it exhibits particularly excellent light shielding properties for a wide range of near-infrared light in the 600-800 nm region. As a result, the absorption properties of the NIR dye can compensate for the suppression of the 700-800 nm reflection properties of the dielectric multilayer film (I) and dielectric multilayer film (II) to reduce flare and ghosting, and the optical filter as a whole can achieve both suppression of flare and ghosting and shielding properties for near-infrared light.

[0073] The dye (NIR1) has a maximum absorption wavelength in the resin between 680 and 870 nm, preferably between 700 and 730 nm. Here, "resin" refers to the resin that constitutes the resin film. The NIR dye may consist of one compound or may contain two or more compounds. In this invention, the resin film preferably further contains, in addition to the dye (NIR1), another near-infrared absorbing dye with a different maximum absorption wavelength. This allows for broad light shielding in the near-infrared region around 700 nm, making it easier for the resin film to satisfy characteristic (iv-3). As the other near-infrared absorbing dye, a dye (NIR2) whose maximum absorption wavelength in the resin is 30 to 130 nm greater than that of dye (NIR1) is preferred. Furthermore, the maximum absorption wavelength of dye (NIR2) is preferably 740 to 870 nm.

[0074] From the viewpoint of the maximum absorption wavelength range, transmittance in the visible light range, solubility in resin, and durability, examples of dyes (NIR1) include squarylium compounds and phthalocyanine compounds, with squarylium compounds being particularly preferred. The maximum absorption wavelength of the squarylium compound, which is the dye (NIR1), is preferably 680 to 740 nm. As the pigment (NIR2), squarylium compounds and cyanine compounds are preferable from the viewpoints of the maximum absorption wavelength region, visible light transmittance, solubility in resins, and durability. Further, the maximum absorption wavelength of the squarylium compound as the pigment (NIR2) is preferably 740 to 770 nm. The maximum absorption wavelength of the cyanine compound as the pigment (NIR2) is preferably 740 to 860 nm.

[0075] <NIR1: Squarylium compound> In addition, when two or more identical symbols are present in the squarylium compound, those symbols may be the same or different. The same applies to the cyanine compound.

[0076] <Squarylium compound (I)>

[0077]

Chemical formula

[0078] However, the symbols in the above formula are as follows. R 24 and R 26 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 20 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an aryl group having 6 to 11 carbon atoms, an aralkyl group having 7 to 18 carbon atoms which may have a substituent and may have an oxygen atom between carbon atoms, -NR 27 R 28 (R 27 and R 28 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, -C(=O)-R 29 (R 29 is a hydrogen atom, a halogen atom, a hydroxyl group, which may have a substituent and may contain an unsaturated bond, an oxygen atom, a saturated or unsaturated ring structure between carbon atoms, a hydrocarbon group having 1 to 25 carbon atoms), -NHR 30 , or, -SO2-R 30 (R 30represents 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 carboxyl group, a sulfo group, or a cyano group, and may contain an unsaturated bond, an oxygen atom, or a saturated or unsaturated ring structure between carbon atoms), or a group (R) represented by the following formula (S). 41 , R 42 each independently represents a hydrogen atom, a halogen atom, or an alkyl group or an alkoxy group having 1 to 10 carbon atoms. k is 2 or 3.).

[0079] [Chemical formula]

[0080] R 21 and R 22 , R 22 and R 25 , and R 21 and R 23 may be connected to each other to form a heterocyclic ring A, a heterocyclic ring B, and a heterocyclic ring C having 5 or 6 members together with a nitrogen atom. When the heterocyclic ring A is formed, R 21 and R 22 as a divalent group -Q- to which these are bonded, represents an alkylene group in which a 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. When the heterocyclic ring B is formed, R 22 and R 25 , and when the heterocyclic ring C is formed, R 21 and R 23 each as a divalent group -X 1 -Y 1 - and -X 2 -Y 2 -(the side bonded to nitrogen is X 1 and X 2 ), X 1 and X 2 are each a group represented by the following formula (1x) or (2x), and Y 1 and Y 2Each of these is a group represented by one of the following formulas (1y) to (5y). 1 and X 2 However, in the case of the base represented by the following formula (2x), Y 1 and Y 2 Each of these may be a single bond, in which case there may be an oxygen atom between the carbon atoms.

[0081] [ka]

[0082] In formula (1x), the four Zs are each independently a hydrogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 6 carbon atoms, or -NR 38 R 39 (R 38 and R 39 Each of these independently represents either a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. 31 ~R 36 Each independently comprises a hydrogen atom, a C1-C6 alkyl group, or a C6-C10 aryl group, R 37 This 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 ~R 37 , R when it does not form a heteroalgebra 21 ~R 23 , and R 25 These may bond with any of the others to form a five-membered ring or a six-membered ring. 31 and R 36 , R 31 and R 37 They may be directly joined. When R does not form a heteroalgebra, 21 , R 22 , R 23 and R 25Each of these independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a C1-C20 alkyl or alkoxy group, a C1-C10 acyloxy group, a C6-C11 aryl group, or a C7-C18 alaryl group which may have substituents or oxygen atoms between carbon atoms.

[0083] Examples of compound (I) include compounds represented by any of formulas (I-1) to (I-3), and from the viewpoint of solubility in the resin, heat resistance and light resistance in the resin, and visible light transmittance of the resin layer containing it, the compound represented by formula (I-1) is particularly preferred.

[0084] [ka]

[0085] The symbols in formulas (I-1) to (I-3) are the same as those specified for the same symbols in formula (I), and the preferred embodiments are also the same.

[0086] In compound (I-1), X 1 As for the base, (2x) is preferred, Y 1 A single bond or group (1y) is preferred. In this case, R 31 ~R 36 Preferably, it is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and more preferably a hydrogen atom or a methyl group. 1 -X 1 Specifically, examples include the divalent organic groups shown in formulas (11-1) to (12-3).

[0087] -C(CH3)2-CH(CH3)- …(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(CH3)2-CH2-CH(CH3)- …(12-2) -C(CH3)2-CH(CH3)-CH2- …(12-3)

[0088] Furthermore, in compound (I-1), R 21 From the viewpoint of solubility, heat resistance, and the steepness of the change near the boundary between the visible and near-infrared regions in the spectral transmittance curve, the group represented by formula (4-1) or (4-2) is independently more preferred.

[0089] [ka]

[0090] In equations (4-1) and (4-2), R 71 ~R 75 This independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms.

[0091] In compound (I-1), R 24 -NR 27 R 28 Preferably. -NR 27 R 28 From the perspective of solubility in resins and coating solvents, -NH-C(=O)-R 29 Or -NH-SO2-R 30 It is preferable.

[0092] In compound (I-1), R 24 -NH-C(=O)-R 29 The compound is shown in formula (I-11).

[0093] [ka]

[0094] R 23 and R 26 These are preferably, independently, a hydrogen atom, a halogen atom, or an alkyl or alkoxy group having 1 to 6 carbon atoms, with a hydrogen atom being more preferred in any case.

[0095] R 29 Preferred substituents include C1-C20 alkyl groups which may have substituents, C6-C10 aryl groups which may have substituents, or C7-C18 alaryl groups which may have substituents and may have oxygen atoms between carbon atoms. Examples of substituents include hydroxyl groups, carboxyl groups, sulfo groups, cyano groups, C1-C6 alkyl groups, C1-C6 fluoroalkyl groups, C1-C6 alkoxy groups, and C1-C6 acyloxy groups.

[0096] R 29 Preferably, the group is selected from linear, branched, or cyclic alkyl groups having 1 to 17 carbon atoms, phenyl groups which may be substituted with alkoxy groups having 1 to 6 carbon atoms, and alaryl groups having 7 to 18 carbon atoms which may have oxygen atoms between carbon atoms.

[0097] R 29 As an example, groups that are hydrocarbon groups having 5 to 25 carbon atoms and having at least one branch may also be used, in which one or more hydrogen atoms may be independently substituted with a hydroxyl group, a carboxyl group, a sulfo group, or a cyano group, and which may contain unsaturated bonds, oxygen atoms, or saturated or unsaturated ring structures between carbon atoms.

[0098] More specifically, compounds (I-11) include those listed in the table below. Furthermore, in the compounds listed in the table below, the meaning of each symbol is the same on both the left and right sides of the squarylium skeleton.

[0099] [Table 1]

[0100] Among these, as the compound (I-11), compounds (1-11-1) to (1-11-12), and compounds (1-11-17) to (1-11-28) are preferable from the viewpoints of solubility in resin, maximum absorption wavelength, light resistance, heat resistance, and high absorbance. Particularly, compounds (1-11-1) to (1-11-12) are preferable from the viewpoints of light resistance and heat resistance. In the configuration of the present invention, since the light shielding property in the ultraviolet region by the dielectric multilayer film is gentle, the light resistance of the dye is particularly important.

[0101] <NIR2: Squarylium compound> The squarylium compound which is the dye (NIR2) is preferably a compound represented by the following formula (II).

[0102] <Squarylium compound (II)>

[0103]

Chemical formula

[0104] However, the symbols in the above formula are as follows. Ring Z is each independently a 5-membered ring or 6-membered ring having 0 to 3 heteroatoms in the ring, and the hydrogen atoms of ring Z may be substituted. R 1 and R 2 、R 2 and R 3 、and R 1 and the carbon atom or heteroatom constituting ring Z may be connected to each other to form hetero rings A1, B1, and C1 together with a nitrogen atom, and in that case, the hydrogen atoms of hetero rings A1, B1, and C1 may be substituted. When no hetero ring is formed, R 1 and R 2 each independently represent a hydrogen atom, a halogen atom, or a hydrocarbon group which may contain an unsaturated bond, a heteroatom, a saturated or unsaturated ring structure between carbon atoms and may have a substituent. R 4 and when no hetero ring is formed, R 3Each of these independently represents an alkyl or alkoxy group which may contain a hydrogen atom, a halogen atom, or a heteroatom between carbon atoms, and which may have substituents.

[0105] Examples of compound (II) include compounds represented by any of formulas (II-1) to (II-3), and from the viewpoint of solubility in the resin and visible light transmittance in the resin, the compound represented by formula (II-3) is particularly preferred.

[0106] [ka]

[0107] In formula (II-1) and formula (II-2), R 1 and R 2 Each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms which may have substituents, and R 3 ~R 6 Each of these independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, which may have substituents.

[0108] In formula (II-3), R 1 , R 4 , and R 9 ~R 12 Each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms which may have substituents, and R 7 and R 8 Each of these independently represents a hydrogen atom, a halogen atom, or a C1-C5 alkyl group which may have substituents.

[0109] R in compound (II-1) and compound (II-2) 1 and R 2 From the viewpoint of solubility in resin, visible light transmittance, etc., an alkyl group having 1 to 15 carbon atoms is preferred, and an alkyl group having 7 to 15 carbon atoms is more preferred, R 1 and R 2 At least one of them is more preferably an alkyl group having a branched chain with 7 to 15 carbon atoms, R1 and R 2 Alkyl groups having branched chains with 8 to 15 carbon atoms are particularly preferred for both.

[0110] R in compound (II-3) 1 From the viewpoint of solubility in transparent resins and visible light transmittance, alkyl groups having 1 to 15 carbon atoms are preferred, alkyl groups having 1 to 10 carbon atoms are more preferred, and ethyl groups and isopropyl groups are particularly preferred.

[0111] R 4 From the viewpoint of visible light transmittance and ease of synthesis, hydrogen atoms and halogen atoms are preferred, with hydrogen atoms being particularly preferred. R 7 and R 8 The following are preferred independently: a hydrogen atom, a halogen atom, and a C1-C5 alkyl group which may be substituted with a halogen atom; a hydrogen atom, a halogen atom, and a methyl group are more preferred.

[0112] R 9 ~R 12 The following are preferred independently: a hydrogen atom, a halogen atom, and a C1-C5 alkyl group which may be substituted with a halogen atom. -CR 9 R 10 -CR 11 R 12 -Examples include the divalent organic groups represented by the following groups (13-1) to (13-5). -CH(CH3)-C(CH3)2- …(13-1) -C(CH3)2-CH(CH3)- …(13-2) -C(CH3)2-CH2- …(13-3) -C(CH3)2-CH(C2H5)- …(13-4) -CH(CH3)-C(CH3)(CH2-CH(CH3)2)-…(13-5)

[0113] More specifically, compounds (II-3) include those shown in the table below. Furthermore, in the compounds shown in the table below, the meaning of each symbol is the same on both the left and right sides of the squarylium skeleton.

[0114]

Table 2

[0115] Among these, as the compound (II-3), compounds (II-3-1) to compounds (II-3-4) are preferable from the viewpoints of solubility in resin, high absorbance coefficient, light resistance, and heat resistance.

[0116] Compounds (I) to (II) can each be produced by known methods. For compound (I), it can be produced by the methods described in U.S. Patent No. 5,543,086, U.S. Patent Application Publication No. 2014 / 0061505, and International Publication No. 2014 / 088063. For compound (II), it can be produced by the method described in International Publication No. 2017 / 135359.

[0117] <NIR2: Cyanine Compound> As the cyanine compound which is the dye (NIR2), it is preferable that it is a compound represented by the following formula (III) and a compound represented by formula (IV).

[0118] <Cyanine Compounds (III), (IV)>

[0119]

Chemical Formula

[0120] However, the symbols in the above formula are as follows. R 101 ~R 109 and R 121 ~R 131 each independently represents a hydrogen atom, 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. R 110 ~R 114 and R 132 ~R 136 each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 15 carbon atoms. X - represents a monovalent anion. n1 and n2 are 0 or 1. -(CH2) n1 A carbocyclic ring containing -, and a hydrogen atom bonded to a carbocyclic ring containing -(CH2) 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 which may have a substituent.

[0121] In the above, the alkyl group (including the alkyl group of the alkoxy group) may be linear, and may include a branched structure or a saturated ring structure. The aryl group refers to a group bonded via carbon atoms constituting an aromatic ring of an aromatic compound, for example, a benzene ring, a naphthalene ring, a biphenyl ring, a furan ring, a thiophene ring, a pyrrole ring, etc. Examples of the substituent in the alkyl group having 1 to 15 carbon atoms or alkoxy group which may have a substituent, or the aryl group having 5 to 20 carbon atoms which may have a substituent include a halogen atom and an alkoxy group having 1 to 10 carbon atoms.

[0122] In formula (III) and formula (IV), R 101 and R<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​132 ~R 136 Each of these is preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms, with hydrogen atoms being more preferred from the viewpoint of obtaining high visible light transmittance.

[0125] R 106 , R 107 , R 128 and R 129 Each of these is 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 linear, cyclic, or branched alkyl groups), and more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. 106 and R 107 , R 128 and R 129 The same group is preferable.

[0126] X - As for, I - BF4 - PF6 - ClO4 - Examples include anions represented by formulas (X1) and (X2), preferably BF4 - , or PF6 - That is the case.

[0127] [ka]

[0128] In the following explanation, in pigment (III), R 101 ~R 114 The part excluding this is also called the skeleton (III). The same applies to the pigment (IV).

[0129] In equation (III), compounds with n1 = 1 are shown in equation (III-1) below, and compounds with n1 = 0 are shown in equation (III-2) below.

[0130] [ka]

[0131] In equations (III-1) and (III-2), R 101 ~R 114 and X - This is the same as in the case of equation (III). R 115 ~R 120 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms which may have substituents, or an aryl group having 5 to 20 carbon atoms. 115 ~R 120 Each of these is 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 linear, cyclic, or branched alkyl groups), and more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. 115 ~R 120 It is preferable that they be the same group.

[0132] In equation (IV), compounds with n² = 1 are shown in equation (IV-1) below, and compounds with n² = 0 are shown in equation (IV-2) below.

[0133] [ka]

[0134] In equations (IV-1) and (IV-2), R 121 ~R 136 and X - This is the same as in case (IV). 137 ~R 142 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl or alkoxy group having 1 to 15 carbon atoms which may have substituents, or an aryl group having 5 to 20 carbon atoms. 137 ~R 142 Each of these is 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 linear, cyclic, or branched alkyl groups), and more preferably a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. 137 ~R 142 It is preferable that they be the same group.

[0135] More specifically, the compounds represented by formulas (III-1), (III-2), (IV-1), and (IV-2) are compounds in which the atoms or groups bonded to each skeleton are those shown in the table below. In all the compounds shown in the table below, R 101 ~R 109 The terms are identical on both sides of the equation. In all the compounds shown in the table below, R 121 ~R 131 The terms on both sides of the equation are identical.

[0136] R in the table below 110 -R 114 and R in the table below 132 -R 136 The symbol indicates the atom or group bonded to the central benzene ring in each formula, and "H" is written when all five are hydrogen atoms. 110 -R 114 If one of the atoms is a substituent and the others are hydrogen atoms, only the combination of the sign of the substituent and the substituent is listed. For example, "R 112 The description "-C(CH3)3" is R 112 This indicates that -C(CH3)3 and the others are hydrogen atoms. 132 -R 136 The same applies to this matter.

[0137] R in the table below 115 -R 120 and R in the table below 137 -R 142 R indicates the atom or group bonded to the central cyclohexane ring in formulas (III-1) and (IV-1), and is denoted as "H" if all six are hydrogen atoms. 115 -R 120 If one of the atoms is a substituent and the others are hydrogen atoms, only the combination of the sign of the substituent and the substituent is listed. 137 -R 142 The same applies to this matter.

[0138] R in the table below 115 -R 118 and R in the table below 137-R 140 represents an atom or a group bonded to the central cyclopentane ring in Formula (III-2) and Formula (IV-2), and when all four are hydrogen atoms, it is described as "H". R 115 -R 118 Among them, when any one is a substituent and the others are hydrogen atoms, only the symbol of the substituent and the combination of the substituents are described. R 137 -R 140 The same applies to R

[0139] [Table 3]

[0140] As the pigment (III-1), among these, from the viewpoints of heat resistance, light resistance, solubility in resins, and simplicity of synthesis, pigments (III-1-1) to (III-1-12) etc. are preferable.

[0141] [Table 4]

[0142] As the pigment (III-2), among these, from the viewpoints of heat resistance, light resistance, solubility in resins, and simplicity of synthesis, pigments (III-2-1) to (III-2-12) etc. are preferable.

[0143] [Table 5] <Q

[0144] As the pigment (IV-1), among these, from the viewpoints of heat resistance, light resistance, solubility in resins, and simplicity of synthesis, pigments (IV-1-1) to (IV-1-12) etc. are preferable.

[0145] [Table 6]

[0146] Among these, as the pigment (IV-2), pigments (IV-2-1) to (IV-2-15) etc. are preferable from the viewpoints of heat resistance, light resistance, solubility in resins, and simplicity of synthesis.

[0147] The pigments (III) and pigments (IV) can be produced, for example, by the methods described in Dyes and pigments 73(2007) 344-352 and J.Heterocyclic chem,42,959(2005).

[0148] The content of the NIR pigment in the resin film is preferably 0.1 to 25 parts by mass, more preferably 0.3 to 15 parts by mass, based on 100 parts by mass of the resin. When combining two or more compounds, the above content is the sum of each compound. When the pigments (NIR1) and the pigment (NIR2) are used in combination, the content of the pigment (NIR1) is preferably 0.1 to 10 parts by mass, and the content of the pigment (NIR2) is preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the resin.

[0149] In addition to the pigments (NIR1) and the pigment (NIR2), the resin film may contain other near-infrared absorbing pigments. From the viewpoint of being able to block light in a wide range in the near-infrared region, pigments having a maximum absorption wavelength larger than that of the pigment (NIR2) are preferable as other near-infrared absorbing pigments. Specifically, cyanine compounds, diimonium compounds, etc. can be mentioned.

[0150] <UV pigment> In addition to the above NIR pigments, the resin film may contain other pigments. As other pigments, pigments (UV) having a maximum absorption wavelength of 370 to 440 nm in the resin are preferable. Thereby, the near-ultraviolet region can be efficiently blocked.

[0151] Examples of UV dyes include oxazole dyes, merocyanine dyes, cyanine dyes, naphthalimide dyes, oxadiazole dyes, oxazine dyes, oxazolidine dyes, naphthalic acid dyes, styryl dyes, anthracene dyes, cyclic carbonyl dyes, and triazole dyes. Among these, merocyanine dyes are particularly preferred. One type may be used alone, or two or more types may be used in combination.

[0152] The pigment (UV) content in the resin film is preferably 0.1 to 15 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of resin. Within this range, a decrease in resin properties is unlikely.

[0153] <Base material composition> The substrate in this filter is a composite substrate in which a resin film is laminated on at least one main surface of near-infrared absorbing glass.

[0154] The resin is not limited to transparent resins, and 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, poly-paraphenylene resin, polyarylene ether phosphine oxide resin, polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, cyclic olefin resin, polyurethane resin, and polystyrene resin can be used. These resins may be used individually or in mixtures of two or more. From the viewpoint of the spectral properties of the resin film, glass transition temperature (Tg), and adhesion, one or more resins selected from polyimide resin, polycarbonate resin, polyester resin, and acrylic resin are preferred.

[0155] When multiple compounds are used as NIR dyes or other dyes, they may be contained in the same resin film, or they may each be contained in separate resin films.

[0156] The resin film can be formed by preparing a coating solution by dissolving or dispersing a dye, a resin or resin raw material component, and other components as needed in a solvent, coating this solution onto a support, drying it, and further curing it as necessary. The support in this case may be the near-infrared absorbing glass used in this filter, or a releaseable support used only when forming the resin film. The solvent may be any dispersion medium or solvent that can stably disperse or dissolve the components.

[0157] Furthermore, the coating solution may contain a surfactant to improve voids caused by minute bubbles, indentations caused by the adhesion of foreign matter, and repulsion during the drying process. In addition, methods such as immersion coating, cast coating, or spin coating can be used for applying the coating solution. After applying the above coating solution to the support, a resin film is formed by drying. Furthermore, if the coating solution contains raw material components of a transparent resin, a curing treatment such as thermosetting or photocuring is performed.

[0158] Furthermore, the resin film can also be manufactured in film form by extrusion molding. The resulting film-like resin film can be laminated onto near-infrared absorbing glass and integrated by thermocompression bonding or the like to produce a substrate.

[0159] The resin film may be present as one layer within the optical filter, or as two or more layers. If there are two or more layers, each layer may have the same or different configuration.

[0160] The thickness of the resin film is preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of in-plane film thickness distribution within the substrate after coating and appearance quality, and preferably 0.5 μm or more from the viewpoint of exhibiting desired spectral characteristics with an appropriate dye concentration. If the optical filter has two or more resin film layers, it is preferable that the total thickness of each resin film is within the above range.

[0161] The shape of the substrate is not particularly limited and may be in the form of a block, plate, or film.

[0162] This filter may also include other components, such as a component (layer) that provides absorption by inorganic nanoparticles that control the transmission and absorption of light in a specific wavelength range. Specific examples of inorganic nanoparticles include ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, and lanthanum boride. ITO nanoparticles and cesium tungstate nanoparticles have high transmittance of visible light and light absorption over a wide range in the infrared wavelength region exceeding 1200 nm, and can therefore be used when shielding against such infrared light is required.

[0163] Based on the above, this specification discloses the following optical filters, etc. [1] An optical filter comprising a substrate, a dielectric multilayer film (I) laminated as the outermost layer on one main surface side of the substrate, and a dielectric multilayer film (II) laminated as the outermost layer on the other main surface side of the substrate, The substrate comprises near-infrared absorbing glass and a resin film laminated on at least one main surface of the near-infrared absorbing glass. The resin film comprises a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1) to (i-8). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 440 to 600 nm. 440-600(0deg)AVE over 86% (i-2) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength IR50 is such that the transmittance is 50% in the range of wavelengths 550 to 750 nm. (0deg)T And, in the spectral transmittance curve at an incident angle of 40 degrees, the wavelength IR50 has a transmittance of 50% in the wavelength range of 550 to 750 nm. (40deg)T The absolute value of the difference is 6 nm or less. (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 700-800 nm. 700-800(0deg)AVE less than 1% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 800 to 1200 nm. 800-1200(0deg)AVE less than 3% (i-5) When the dielectric multilayer film (I) side is the incident direction, the spectral reflectance curve at an incident angle of 5 degrees shows the average reflectance RI at wavelengths of 440 to 600 nm. 440-600(5deg)AVE less than 4% (i-6) When the dielectric multilayer film (I) side is the incident direction, the average reflectance RI at wavelengths of 800 to 1200 nm is shown in the spectral reflectance curve at an incident angle of 5 degrees. 800-1200(5deg)AVE over 95% (i-7) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 700-800 nm. 700-800(40deg)AVE less than 5.5% (i-8) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 800 to 1200 nm. 800-1200(40deg)AVE over 10% [2] The optical filter according to [1], wherein the optical filter further satisfies the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 50 degrees shows the average reflectance RII at wavelengths of 700-800 nm. 700-800(50deg)AVE 8% or less (i-10) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 50 degrees shows the average reflectance RII at wavelengths of 800 to 1200 nm. 800-1200(50deg)AVE over 10% [3] The optical filter according to [1] or [2], wherein the near-infrared absorbing glass satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Average internal transmittance T at wavelength 400~600nm 400-600AVE over 90% (iii-2) Average internal transmittance T at wavelengths of 700-800 nm 700-800AVE less than 40% (iii-3) Average internal transmittance T at wavelength 800~1200nm 800-1200AVE less than 40% [4] The dielectric multilayer film (II) is laminated on the resin film, and is an optical filter according to any one of [1] to [3]. [5] The dielectric multilayer film (II) is an optical filter according to any of [1] to [4], satisfying all of the following spectral characteristics (v-II-1) to (v-II-2). (v-II-1) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII is observed at wavelengths of 700-800 nm. 700-800(5deg)MAX 8% or less (v-II-2) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII at wavelengths of 700-800 nm 700-800(5deg)AVE less than 6% [6] The dielectric multilayer film (II) is an optical filter according to any of [1] to [5], satisfying all of the following spectral characteristics (v-II-3) to (v-II-5). (v-II-3) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII is observed at wavelengths of 700-800 nm. 700-800(5deg)MAX less than 7.5% (v-II-4) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII at wavelengths of 700-800 nm 700-800(5deg)AVE less than 5.5% (v-II-5) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is calculated for wavelengths of 800-1200 nm. 800-1200(5deg)AVE over 20% [7] The dielectric multilayer film (II) is an optical filter according to any one of [1] to [6], further satisfying the following spectral characteristics (v-II-6). (v-II-6) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is found at wavelengths of 440-600 nm. 440-600(5deg)AVE less than 6% [8] The optical filter according to any one of [1] to [7], wherein the optical filter further satisfies the following spectral characteristics (i-12). (i-12) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength at which the transmittance is 50% in the range of 550 to 750 nm is defined as IR50. (0deg)T year, When the dielectric multilayer film (I) side is the incident direction, the wavelength at which the reflectance is 50% in the spectral reflectance curve at an incident angle of 5 degrees, in the wavelength range of 550 to 750 nm, is defined as IR50. (5deg)R In that case, IR50 (0deg)T and IR50 (5deg)R The absolute value of the difference is 85 nm or more. [9] An optical filter according to any of [1] to [8], wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-3). (iv-1) Average internal transmittance T at wavelength 440~600nm 440-600AVE over 90% (iv-2) Average internal transmittance T at wavelength 700~800nm 700-800AVE less than 50% (iv-3) In the spectral transmittance curve for wavelengths of 600-800 nm, the shortest wavelength at which the internal transmittance is 50% is IR50. (S) The longest wavelength is IR50 (L) In that case, IR50 (L) -IR50 (S) ≥100nm

[10] The optical filter according to any one of [1] to [9], wherein the resin film further comprises a dye (NIR2) having a maximum absorption wavelength of 680 to 870 nm in the resin and having a different maximum absorption wavelength from the dye (NIR1). An imaging device equipped with an optical filter as described in any of

[11] , [1], to

[10] . [Examples]

[0164] Next, the present invention will be described in more detail with reference to examples. A UV-Vis spectrophotometer (Hitachi High-Technologies Corporation, UH-4150 model) was used to measure each spectral characteristic. Note that unless the angle of incidence is specifically stated, the spectral characteristics are measured at an angle of incidence of 0° (perpendicular to the main surface of the optical filter).

[0165] The dyes used in each example are as follows: Compound NIR1 (squallium compound): Synthesized according to Japanese Patent Publication No. 2017-110209. Compound NIR2 (squallium compound): Synthesized according to Japanese Patent Publication No. 2017-110209. Compound NIR3 (cyanine compound): Synthesized according to the method described in Dyes and Pigments, 73, 344-352 (2007). Compound NIR4 (squallium compound): Synthesized according to International Publication No. 2017 / 135359. Compound NIR5 (phthalocyanine compound): Synthesized based on the method described in Journal of Physical Chemistry, C 117(14), 7097-7106, 2013. Compound UV1 (merocyanine compound): Synthesized according to German Patent Publication No. 10109243.

[0166] [ka]

[0167] <Spectral properties of pigments in resin> A polyimide resin solution with a resin concentration of 8.5% by mass was prepared by dissolving polyimide resin (product name "C3G30G" manufactured by Mitsubishi Gas Chemical Company, Inc., refractive index 1.59) in a γ-butyrolactone (GBL):cyclohexanone ratio of 1:1 (by mass). Each of the above-mentioned dyes was added to the resin solution at a concentration of 7.5 parts by mass per 100 parts by mass of resin, and the mixture was stirred and dissolved at 50°C for 2 hours to obtain a coating solution. The obtained coating solution was applied to alkali glass (SCHOTT, D263 glass, 0.2 mm thick) by spin coating, forming coating films with a thickness of approximately 1.0 μm. The obtained coating film was subjected to transmission spectroscopy (incident angle 0 degrees) and reflection spectroscopy (incident angle 5 degrees) in the wavelength range of 350 nm to 1200 nm using a spectrophotometer. The spectral internal transmittance curve was calculated using the obtained spectral transmittance curve and spectral reflectance curve. The spectral properties of each of the above dyes in polyimide resin are shown in the table below.

[0168] [Table 7]

[0169] <Spectral characteristics of near-infrared absorbing glass> The following phthalic acid glass was prepared as near-infrared absorbing glass. Absorption glass 1: AGC Corporation, NF50T, 0.2mm thickness (phthalic acid glass) Absorption glass 2: AGC Corporation, NF50EXA, 0.2mm thickness (phthalic acid glass) Absorption glass 3: AGC Corporation, NF50P, 0.2mm thick (phthalic acid glass) Transmission (incident angle 0 degrees) and reflection (incident angle 5 degrees) measurements were performed on near-infrared absorbing glass using a spectrophotometer in the wavelength range of 350 nm to 1200 nm. The spectral internal transmittance curve was calculated using the obtained spectral transmittance curve and spectral reflectance curve. The obtained spectral characteristics are shown in the table below.

[0170] [Table 8]

[0171] As shown above, the near-infrared absorbing glass used has high transmittance in the visible light region and excellent light-shielding properties in the near-infrared region.

[0172] <Examples 1-1 to 1-4: Spectral characteristics of resin films> One of the above dyes was mixed at the concentrations listed in the table below into a polyimide resin solution prepared in the same manner as when the spectral characteristics of each dye compound were calculated. The mixture was then stirred and dissolved at 50°C for 2 hours to obtain a coating solution. The obtained coating solution was applied to alkali glass (SCHOTT, D263 glass, 0.2 mm thick) by spin coating to form a resin film with a thickness of 1.0 μm. The obtained resin film was subjected to transmission spectroscopy (incident angle 0 degrees) and reflection spectroscopy (incident angle 5 degrees) in the wavelength range of 350 nm to 1200 nm using a spectrophotometer. The spectral internal transmittance curve was calculated using the obtained spectral transmittance curve and spectral reflectance curve. The obtained spectral characteristics are shown in the table below. Furthermore, the spectral transmittance curves for the resin film of Example 1-1 and the resin film of Example 1-2 are shown in Figure 4. Examples 1-1 to 1-4 are for reference only.

[0173] [Table 9]

[0174] As shown above, the obtained resin film has high transmittance in the visible light region and excellent light shielding properties in the near-infrared region of 700-800 nm. Furthermore, the resin films of Examples 1-2 to 1-4 are IR 50(L) and IR 50(S) The difference exceeds 100 nm, indicating that it was able to absorb light across a wide range in the near-infrared region of 700-800 nm.

[0175] <Example 2-1: Spectral characteristics of dielectric multilayer film (I)> A dielectric multilayer film (I) was formed on the surface of alkali glass (SCHOTT, D263 glass, 0.2 mm thick) by alternately depositing TiO2 and SiO2 under the conditions shown in the table below. The spectral reflectance curves of the obtained dielectric multilayer films were measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The obtained spectral characteristics are shown in the table below. Please note that Example 2-1 is for reference only.

[0176] [Table 10]

[0177] <Examples 3-1 to 3-4: Spectroscopic properties of dielectric multilayer films (II)> A dielectric multilayer film (II) was formed on the surface of alkali glass (SCHOTT, D263 glass, 0.2 mm thick) by alternately depositing TiO2 and SiO2 under the conditions shown in the table below. The spectral reflectance curves of the obtained dielectric multilayer films were measured in the wavelength range of 350 to 1200 nm using an ultraviolet-visible spectrophotometer. The obtained spectral characteristics are shown in the table below. Furthermore, the spectral reflectance curves of the dielectric multilayer film (II) of Example 3-3 and the dielectric multilayer film (II) of Example 3-4 are shown in Figure 5. Examples 3-1 to 3-4 are for reference only.

[0178] [Table 11]

[0179] As shown above, Examples 3-3 and 3-4 yielded dielectric multilayer films with particularly low reflectivity in the 700-800 nm range.

[0180] <Examples 4-1 to 4-8: Spectral characteristics of optical filters> A dielectric multilayer film (I) (reflective film) was deposited on one main surface of the substrate by vapor deposition in the same manner as in Example 2-1. However, in Example 4-6 only, the dielectric multilayer film (I) was deposited in the same manner as in Example 3-1. A resin film was prepared on the other surface of the substrate by vapor deposition in the same manner as in any of Examples 1-1 to 1-4. Furthermore, a dielectric multilayer film (II) (anti-reflective film) was deposited on the resin film by vapor deposition in the same manner as in any of Examples 3-1 to 3-4 to create an optical filter. For the obtained optical film, spectral transmittance curves at incident angles of 0 and 40 degrees in the wavelength range of 350 to 1200 nm were measured using a UV-Vis spectrophotometer. Spectral reflectance curves at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side, and spectral reflectance curves at incident angles of 5 degrees, 40 degrees, and 50 degrees with the incident direction facing the dielectric multilayer film (II) side were also measured. The substrate used was one of the following: absorption glass 1-3 as described above, transparent alkali glass (SCHOTT, D263 glass, 0.2 mm thick), or transparent resin film (polycarbonate film, Teijin, PureAce, 80 μm thick). From the obtained spectral characteristics data, the following characteristics were calculated as shown in the table below. Figure 6 shows the spectral transmittance curves for the optical filter of Example 4-1 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side. Figure 7 shows the spectral reflectance curve of the optical filter in Example 4-1 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side. Figure 8 shows the spectral transmittance curves for the optical filter of Example 4-2 at incident angles of 0 and 40 degrees, and the spectral reflectance curve at an incident angle of 5 degrees with the incident direction facing the dielectric multilayer film (I) side. Figure 9 shows the spectral reflectance curve of the optical filter in Example 4-2 at an incident angle of 40 degrees, with the incident direction facing the dielectric multilayer film (II) side. Examples 4-1 to 4-5 are examples, while Examples 4-6 to 4-8 are comparative examples.

[0181] [Table 12]

[0182] From the above results, it can be seen that the optical filters in Examples 4-1 to 4-5 have high transmittance in the visible light region and high shielding in the near-infrared light region of 700 to 1200 nm, and that the reflectance at an incident angle of 40 degrees in the 700 to 800 nm region is kept low on the back surface, i.e., the dielectric multilayer film (II) side. Furthermore, IR50 (0deg)T and IR50 (5deg)R Examples 4-4 to 4-5, where the absolute value of the difference is 85 nm or more, suppress both the reflection from the back surface in the 700-800 nm range and the transmittance in the 700-800 nm range more effectively than Examples 4-1 to 4-3. In other words, the light shielding in the 700-800 nm range is ensured by the absorption of the NIR dye rather than the reflection of the dielectric multilayer film, and it can be said that this is an optical filter that can suppress the generation of stray light due to reflection from the back surface. On the other hand, the optical filters in Examples 4-6 to 4-8 do not suppress the reflectance at an incident angle of 40 degrees in the 700-800 nm range on the dielectric multilayer film (II) side. The optical filter in Example 4-6 does not use a dielectric multilayer film (II) that satisfies specific spectral characteristics. The optical filter in Example 4-7 uses transparent glass that does not have infrared absorption capabilities as its substrate. The optical filter in Example 4-8 does not use a dielectric multilayer film (II) that satisfies specific spectral characteristics.

[0183] 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 invention. This application is based on Japanese Patent Application No. 2022-032184, filed on 2 March 2022, the contents of which are incorporated herein by reference. [Industrial applicability]

[0184] The optical filter of the present invention has spectral characteristics that suppress flare and ghosting, and exhibit excellent transmittance in the visible light region and shielding in the near-infrared light region. It is useful in applications such as imaging devices like cameras and sensors for transport aircraft, where performance has been steadily improving in recent years. [Explanation of symbols]

[0185] 1A, 1B…Optical filters, 10…Substrate, 11…Near-infrared absorbing glass, 12, 12A, 12B…Resin films, 20I, 20II…Dielectric multilayer films

Claims

1. An optical filter comprising a substrate, a dielectric multilayer film (I) on one main surface side of the substrate, and a dielectric multilayer film (II) on the other main surface side of the substrate, The substrate comprises near-infrared absorbing glass and a resin film. The resin film comprises a resin and a dye (NIR1) having a maximum absorption wavelength of 680 to 870 nm in the resin. The optical filter is an optical filter that satisfies all of the following spectral characteristics (i-1), (i-4), (i-5), and (i-7). (i-1) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 440 to 600 nm. ４４０－６００（０ｄｅｇ）ＡＶＥ over 86% (i-4) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T for wavelengths of 800 to 1200 nm. ８００－１２００（０ｄｅｇ）ＡＶＥ less than 3% (i-5) When the dielectric multilayer film (I) side is the incident direction, in the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RI at wavelengths of 440 to 600 nm ４４０－６００（５ｄｅｇ）ＡＶＥ less than 4% (i-7) When the dielectric multilayer film (II) side is the incident direction, the spectral reflectance curve at an incident angle of 40 degrees shows the average reflectance RII at wavelengths of 700 to 800 nm. ７００－８００（４０ｄｅｇ）ＡＶＥ 5.5% or less

2. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-2). (i-2) The absolute difference between the wavelength IR50 (0deg)T at which the transmittance is 50% in the wavelength range of 550-750 nm in the spectral transmittance curve at an incident angle of 0 degrees, and the wavelength IR50 (40deg)T at which the transmittance is 50% in the wavelength range of 550-750 nm in the spectral transmittance curve at an incident angle of 40 degrees, is 6 nm or less.

3. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-3). (i-3) In the spectral transmittance curve at an incident angle of 0 degrees, the average transmittance T 700-800 (0 deg) AVE for wavelengths of 700-800 nm is 1% or less.

4. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-6). (i-6) When the dielectric multilayer film (I) side is the incident direction, the spectral reflectance curve at an incident angle of 5 degrees shows that the average reflectance RI 800-1200 (5deg) AVE at wavelengths of 800-1200 nm is 95% or higher.

5. The optical filter according to claim 1, further satisfying the following spectral characteristics (i-8). (i-8) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII 800-1200 (40deg) AVE in the spectral reflectance curve at an incident angle of 40 degrees is 10% or more in the wavelength range of 800-1200 nm.

6. The optical filter according to claim 1, wherein the average transmittance T 440-600 (40deg) AVE for wavelengths of 440-600 nm in the spectral transmittance curve at an incident angle of 40 degrees is 85.6% or more.

7. The optical filter according to claim 1, wherein the average transmittance T 800-1200 (40deg) AVE for wavelengths of 800 to 1200 nm in the spectral transmittance curve at an incident angle of 40 degrees is 2.6% or less.

8. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-9) to (i-10). (i-9) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII in the spectral reflectance curve at an incident angle of 50 degrees is in the wavelength range of 700 to 800 nm. ７００－８００（５０ｄｅｇ）ＡＶＥ 8% or less (i-10) When the dielectric multilayer film (II) side is the incident direction, the average reflectance RII in the spectral reflectance curve at an incident angle of 50 degrees is in the wavelength range of 800 to 1200 nm. ８００－１２００（５０ｄｅｇ）ＡＶＥ over 10%

9. The optical filter according to claim 1, wherein the near-infrared absorbing glass satisfies all of the following spectral characteristics (iii-1) to (iii-3). (iii-1) Average internal transmittance T for wavelengths of 400 to 600 nm ４００－６００ＡＶＥ over 90% (iii-2) Average internal transmittance T at wavelengths of 700-800 nm ７００－８００ＡＶＥ less than 40% (iii-3) Average internal transmittance T at wavelengths of 800 to 1200 nm ８００－１２００ＡＶＥ is 40% or less

10. The optical filter according to claim 1, wherein the dielectric multilayer film (II) is laminated on the resin film.

11. The optical filter according to claim 1, wherein the dielectric multilayer film (II) satisfies all of the following spectral characteristics (v-II-1) to (v-II-2). (v-II-1) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII is observed at wavelengths of 700-800 nm. ７００－８００（５ｄｅｇ）ＭＡＸ 8% or less (v-II-2) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII at wavelengths of 700-800 nm ７００－８００（５ｄｅｇ）ＡＶＥ less than 6%

12. The optical filter according to claim 1, wherein the dielectric multilayer film (II) satisfies all of the following spectral characteristics (v-II-3) to (v-II-5). (v-II-3) In the spectral reflectance curve at an incident angle of 5 degrees, the maximum reflectance RII is observed at wavelengths of 700-800 nm. ７００－８００（５ｄｅｇ）ＭＡＸ 7.5% or less (v-II-4) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII at wavelengths of 700-800 nm ７００－８００（５ｄｅｇ）ＡＶＥ 5.5% or less (v-II-5) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is found at wavelengths of 800 to 1200 nm. ８００－１２００（５ｄｅｇ）ＡＶＥ over 20%

13. The optical filter according to claim 1, wherein the dielectric multilayer film (II) further satisfies the following spectral characteristics (v-II-6). (v-II-6) In the spectral reflectance curve at an incident angle of 5 degrees, the average reflectance RII is found at wavelengths of 440-600 nm. ４４０－６００（５ｄｅｇ）ＡＶＥ less than 6%

14. The optical filter according to claim 1, wherein the optical filter further satisfies the following spectral characteristics (i-12). (i-12) In the spectral transmittance curve at an incident angle of 0 degrees, the wavelength at which the transmittance is 50% in the range of 550 to 750 nm is defined as IR50. （０ｄｅｇ）Ｔ year, When the dielectric multilayer film (I) side is the incident direction, the wavelength at which the reflectance is 50% in the spectral reflectance curve at an incident angle of 5 degrees, in the wavelength range of 550 to 750 nm, is defined as IR50. （５ｄｅｇ）Ｒ In that case, IR50 （０ｄｅｇ）Ｔ and IR50 （５ｄｅｇ）Ｒ The absolute value of the difference is 85 nm or more.

15. The optical filter according to claim 1, wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-3). (iv-1) Average internal transmittance T for wavelengths 440 to 600 nm ４４０－６００ＡＶＥ over 90% (iv-2) Average internal transmittance T for wavelengths of 700 to 800 nm ７００－８００ＡＶＥ less than 50% (iv-3) In the spectral transmittance curve for wavelengths of 600-800 nm, the shortest wavelength at which the internal transmittance is 50% is IR50. （Ｓ） The longest wavelength is IR50 （Ｌ） In that case, IR50 （Ｌ） -IR50 （Ｓ） ≧100nm

16. The optical filter according to claim 1, wherein the resin film further comprises a dye (NIR2) having a maximum absorption wavelength in the resin between 680 and 870 nm and having a different maximum absorption wavelength from the dye (NIR1).

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

Images