Optical filter

Abstract

The present invention pertains to an optical filter provided with a dielectric multilayer film (1), a base material having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film (2) in this order, the resin film containing a near-infrared absorbing dye and a resin, the near-infrared absorbing glass being a fluorophosphate glass containing P, Cu, and F, the optical filter satisfies all specific spectral characteristics (i-1) to (i-5).

Description

Technical Field

[0001] The present invention relates to a filter that allows visible light to pass through and blocks near-infrared light. Background Art

[0002] In an imaging device using a solid-state imaging element, in order to reproduce tones well and obtain a clear image, a filter that allows light in the visible light region (hereinafter also referred to as "visible light") to pass through and blocks light in the near-infrared wavelength range (hereinafter also referred to as "near-infrared light") is used.

[0003] Examples of such filters include: a reflective filter that alternately stacks dielectric thin films (dielectric multilayer films) having different refractive indices on one or both sides of a transparent substrate and uses the interference of light to reflect the light to be shielded; an absorptive filter that uses glass or a pigment that absorbs light in a specific wavelength range to absorb the light to be shielded; various types such as a filter obtained by combining a reflective type and an absorptive type.

[0004] A filter containing a copper complex that absorbs light in the near-infrared region is described in Patent Document 1.

[0005] A filter containing a pigment that absorbs light in the near-infrared region is described in Patent Document 2.

[0006] A filter including glass that absorbs light in the near-infrared region and a reflective layer including a dielectric multilayer film is described in Patent Document 3.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent No. 6802938

[0010] Patent Document 2: International Publication No. 2019 / 168090

[0011] Patent Document 3: International Publication No. 2019 / 151348 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] In the filter described in Patent Document 1, a copper complex that absorbs light is coated on phosphate glass, and the moisture resistance is weak, and there is room for improvement in terms of weather resistance.

[0014] In the filter described in Patent Document 2, only the absorption characteristics of the pigment are used to widely shield the light in the near-infrared light region, resulting in a decrease in the transmittance in the visible light region, and there is room for improvement in this regard.

[0015] In addition, in a filter that utilizes reflection of a dielectric multilayer film as described in Patent Document 3, since the optical film thickness of the dielectric multilayer film varies according to the incident angle of light, changes in the spectral transmittance curve and spectral reflectance curve due to the incident angle are a concern. For example, when the amount of light in the visible light region changes under conditions of a high incident angle, there is a problem of reduced image reproducibility. In particular, with the recent trend of reducing the height of camera modules, it is envisioned that they will be used under conditions of a high incident angle, and thus a filter that is not easily affected by the incident angle is required.

[0016] An object of the present invention is to provide a filter having excellent weather resistance, excellent transmittance in the visible light region, excellent shielding property in the near-infrared light region, particularly excellent shielding property in a wide range including around 1200 nm, and small changes in spectral characteristics even under conditions of a high incident angle.

[0017] Means for Solving the Problem

[0018] The present invention provides a filter and the like having the following configuration.

[0019] [1] A filter that sequentially includes a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2, wherein

[0020] the resin film contains a near-infrared absorbing pigment and a resin,

[0021] the near-infrared absorbing glass is a fluoro-phosphate glass containing P, Cu, and F,

[0022] the filter satisfies all of the following spectral characteristics (i-1) to (i-5):

[0023] (i-1) The absolute value of the difference between the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 60 degrees 440-600(60deg)AVE is 15% or less;

[0024] (i-2) The average transmittance T 440-600(0deg)AVE is 75% or more;

[0025] (i-3) The wavelength IR_T at which the transmittance is 50% under the condition of an incident angle of 0 degrees 50(0deg) is in the range of 580 nm to 640 nm;

[0026] (i-4) The average transmittance T at a wavelength of 700 nm to 800 nm under the condition of an incident angle of 0 degrees 700-800(0deg)AVE is 1.1% or less;

[0027] (i-5) Average transmittance T at a wavelength of 800 nm to 1200 nm under the condition that the incident angle is 0 degrees 800-1200(0deg)AVE is 5% or less.

[0028] Advantages of the Invention

[0029] According to the present invention, it is possible to provide a filter having excellent weather resistance, excellent transmittance in the visible light region, excellent shielding property in the near-infrared light region, particularly excellent shielding property in a wide range including around 1200 nm, and small change in spectral characteristics even under the condition of a high incident angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 FIG. is a cross-sectional view schematically showing an example of a filter of one embodiment.

[0031] Figure 2 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 1.

[0032] Figure 3 FIG. is a graph showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, on the side of dielectric multilayer film 1) of the filter of Example 1.

[0033] Figure 4 FIG. is a graph showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, on the side of dielectric multilayer film 2) of the filter of Example 1.

[0034] Figure 5 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 2.

[0035] Figure 6 FIG. is a graph showing the spectral reflectance curves (5-degree reflectance, 60-degree reflectance, on the side of dielectric multilayer film 1) of the filter of Example 2.

[0036] Figure 7 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 3.

[0037] Figure 8 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 4.

[0038] Figure 9 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 5.

[0039] Figure 10 FIG. is a graph showing the spectral transmittance curves (0-degree transmittance, 60-degree transmittance) of the filter of Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, embodiments of the present invention will be described.

[0041] In this specification, the near-infrared absorbing pigment may sometimes be simply referred to as "NIR pigment", and the ultraviolet absorbing pigment may be simply referred to as "UV pigment".

[0042] 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 pigment containing compound (I) is also referred to as pigment (I), and the same applies to other pigments. In addition, the group represented by formula (I) is also described as group (I), and the same applies to groups represented by other formulas.

[0043] In this specification, the internal transmittance is the transmittance obtained by subtracting the influence of interface reflection from the measured transmittance and represented by the formula {measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))} × 100.

[0044] In this specification, a transmittance of, for example, 90% or more in a specific wavelength range means that the transmittance is not less than 90% in the entire wavelength range, that is, the minimum transmittance in the wavelength range is 90% or more. Similarly, a transmittance of, for example, 1% or less in a specific wavelength range means that the transmittance is not more than 1% in the entire wavelength range, that is, the maximum transmittance in the wavelength range is 1% or less. The same applies to the internal transmittance. The average transmittance and average internal transmittance in a specific wavelength range are the arithmetic means of the transmittance and internal transmittance per 1 nm in the wavelength range. The reflectance when the incident direction is the dielectric multilayer film side is the optical property of the light reflected after the measurement light is incident on the surface of the dielectric multilayer film provided in the filter.

[0045] The spectral characteristics can be measured using an ultraviolet-visible spectrophotometer.

[0046] In this specification, "~" indicating a numerical range includes the upper and lower limits.

[0047] <Filter>

[0048] The filter of this embodiment sequentially includes a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2. The resin film contains a near-infrared absorbing pigment and a resin, and the near-infrared absorbing glass is a fluoro-phosphate glass containing P, Cu, and F.

[0049] In the present invention, as described later, the light shielding property of the filter is preferably ensured by the absorption characteristics of the near-infrared absorbing glass and the near-infrared absorbing pigment, and the reflection characteristics of the dielectric multilayer film. Since the absorption characteristics are less affected by the incident angle of light, a filter with small spectral characteristic changes even under high incident angle conditions can be obtained.

[0050] The configuration example of the filter of the present embodiment will be described with reference to the drawings. Figure 1 It is a cross-sectional view schematically showing an example of the filter of one embodiment.

[0051] Figure 1 The shown filter 1B is an example including a dielectric multilayer film 21, a base material 40 having a near-infrared absorbing glass 10 and a resin film 30, and a dielectric multilayer film 22.

[0052] The filter of the present embodiment satisfies all of the following spectral characteristics (i-1) to (i-5).

[0053] (i-1) The absolute value of the difference between the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 0 degree 440-600(0deg)AVE and the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 60 degrees 440-600(60deg)AVE is 15% or less;

[0054] (i-2) The average transmittance T 440-600(0deg)AVE is 75% or more;

[0055] (i-3) The wavelength IR_T when the transmittance is 50% under the condition of an incident angle of 0 degree 50(0deg) is in the range of 580 nm to 640 nm;

[0056] (i-4) The average transmittance T at a wavelength of 700 nm to 800 nm under the condition of an incident angle of 0 degree 700-800(0deg)AVE is 1.1% or less;

[0057] (i-5) The average transmittance T at a wavelength of 800 nm to 1200 nm under the condition of an incident angle of 0 degree 800-1200(0deg)AVE is 5% or less.

[0058] The filter of the present embodiment that satisfies all the spectral characteristics (i-1) to (i-5) has high visible light transmittance as shown in characteristic (i-2), and has high near-infrared light shielding property in a wide range of 800 nm to 1200 nm as shown in characteristics (i-4) and (i-5). In addition, as shown in characteristic (i-3), it has a wavelength at which the transmittance is 50% under the condition that the incident angle is 0 degrees in a specific wavelength range, and as shown in characteristic (i-1), even under the condition of a high incident angle, the change in the spectral characteristics of visible light is small.

[0059] Satisfying the spectral characteristics (i-1) and (i-2) means that even under the condition of a high incident angle, the visible light transmittance does not decrease, and the visible light transmittance is excellent.

[0060] The absolute value of the difference in the spectral characteristic (i-1) is preferably 15% or less, more preferably 10% or less.

[0061] Average transmittance T 440-600(0deg)AVE It is preferably 76% or more, more preferably 77% or more.

[0062] The spectral characteristics (i-1) and (i-2) can be achieved, for example, by using a dielectric multilayer film with low reflectance in the visible light region, using a near-infrared absorbing pigment with high transmittance in the visible light region, and using fluoro-phosphate glass as a near-infrared absorbing glass.

[0063] Satisfying the spectral characteristic (i-3) means shielding the light in the near-infrared light region and effectively obtaining the visible light transmitted light.

[0064] Wavelength IR_T 50(0deg) It is preferably in the range of 580 nm to 630 nm, more preferably in the range of 590 nm to 625 nm.

[0065] The spectral characteristic (i-3) can be achieved, for example, by using the fluoro-phosphate glass described later as a near-infrared absorbing glass.

[0066] Satisfying the spectral characteristic (i-4) means excellent near-infrared light shielding property.

[0067] Average transmittance T 700-800(0deg)AVE It is preferably 0.6% or less, more preferably 0.3% or less, and particularly preferably 0.1% or less.

[0068] The spectral characteristic (i-4) can be achieved, for example, by using the squaraine pigment described later as a near-infrared absorbing pigment and using the fluoro-phosphate glass described later as a near-infrared absorbing glass. It can be achieved by using the fluoro-phosphate glass described later as a near-infrared absorbing glass.

[0069] Satisfying the spectral characteristic (i-5) means excellent light-shielding property in a wide range of near-infrared light region up to around 1200 nm.

[0070] Average transmittance T 800-1200(0deg)AVE Is preferably 4% or less, more preferably 3% or less.

[0071] The spectral characteristic (i-5) can be achieved, for example, by using the fluorophosphate glass described below as the near-infrared absorbing glass.

[0072] The filter of the present embodiment preferably satisfies all of the following spectral characteristics (i-6) to (i-7).

[0073] (i-6) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 5 degrees 440-650(5deg)AVE Is 1.5% or less;

[0074] (i-7) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 nm to 1200 nm under the condition that the incident angle is 5 degrees 850-1200(5deg)AVE Is 60% or more.

[0075] The spectral characteristics (i-6) to (i-7) substantially reflect the reflection characteristics of the medium multilayer film 1, which means that the visible light reflection characteristics of the medium multilayer film 1 are small and it has reflection characteristics in the near-infrared light region.

[0076] Average reflectance R1 440-650(5deg)AVE Is more preferably 1.3% or less, further preferably 1.2% or less, and particularly preferably 1.1% or less.

[0077] Average reflectance R1 850-1200(5deg)AVE Is more preferably 63% or more, further preferably 65% or more, and particularly preferably 70% or more. In addition, when the reflection characteristics in the near-infrared light region are too strong, the visible light transmittance is likely to change under the condition of a high incident angle. Therefore, the average reflectance R1 850-1200(5deg)AVE Is preferably 95% or less, more preferably 90% or less.

[0078] The filter of the present embodiment preferably satisfies the following spectral characteristic (i-8).

[0079] (i-8) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 60 degrees 440-650(60deg)AVE Is 10% or less.

[0080] The spectral characteristic (i-8) substantially reflects the reflection characteristic of the dielectric multilayer film 1, which means that the visible light reflection characteristic of the dielectric multilayer film 1 is small even under the condition of a high incident angle.

[0081] Average reflectance R1 440-650(60deg)AVE More preferably, it is 9% or less, and still more preferably, it is 8.5% or less.

[0082] The filter of the present embodiment preferably satisfies all of the following spectral characteristics (i-9) to (i-10).

[0083] (i-9) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 nm to 650 nm under the condition of an incident angle of 5 degrees 440-650(5deg)AVE is less than 2.0%;

[0084] (i-10) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 nm to 850 nm under the condition of an incident angle of 5 degrees 700-850(5deg)AVE is 1.2% or less.

[0085] The spectral characteristics (i-9) to (i-10) substantially reflect the reflection characteristic of the dielectric multilayer film 2, which means that the dielectric multilayer film 2 is an antireflection film with small reflection characteristics in both the visible light region and the near-infrared light region.

[0086] Average reflectance R2 440-650(5deg)AVE More preferably, it is 1.70% or less, and still more preferably, it is 1.53% or less.

[0087] Average reflectance R2 700-850(5deg)AVE More preferably, it is 1.1% or less, and still more preferably, it is 1.0% or less, and particularly preferably, it is 0.8% or less.

[0088] The filter of the present embodiment preferably satisfies all of the following spectral characteristics (i-11) to (i-12).

[0089] (i-11) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 nm to 650 nm under the condition of an incident angle of 60 degrees 440-650(60deg)AVE is less than 10%;

[0090] (i-12) When the dielectric multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 nm to 850 nm under the condition of an incident angle of 60 degrees 700-850(60deg)AVE is 8% or less.

[0091] The spectral characteristics (i-11) to (i-12) substantially reflect the reflection characteristics of the dielectric multilayer film 2, which means that the dielectric multilayer film 2 is an antireflection film with small reflection characteristics in both the visible light region and the near-infrared light region even under the condition of a high incident angle.

[0092] Average reflectance R2 440-650(60deg)AVE More preferably, it is 9% or less, and further preferably, it is 8.5% or less.

[0093] Average reflectance R2 700-850(60deg)AVE More preferably, it is 7.5% or less, further preferably, it is 7.0% or less, and particularly preferably, it is 6% or less.

[0094] The filter of this embodiment preferably satisfies the following spectral characteristic (i-13).

[0095] (i-13) When the dielectric multilayer film 1 side is the incident direction, the wavelength IR_R at which the reflectance is 50% under the condition of an incident angle of 5 degrees in the wavelength range of 750 nm to 900 nm 50(5deg) And the wavelength IR_T at which the transmittance is 50% under the condition of an incident angle of 5 degrees in the wavelength range of 500 nm to 700 nm 50(5deg) The absolute value of the difference is 160 nm or more.

[0096] Satisfying the spectral characteristic (i-13) means that the light shielding region of the reflection characteristic and the light shielding region of the absorption characteristic are separated.

[0097] The absolute value of the difference in the spectral characteristic (i-13) is more preferably 165 nm or more, further preferably 170 nm or more, and particularly preferably 185 nm or more.

[0098] The filter of this embodiment preferably satisfies all of the following spectral characteristics (i-14) to (i-15).

[0099] When the dielectric multilayer film 1 side is the incident direction, the absorption loss amount in the wavelength range of X nm to Y nm is defined as follows X-Y :

[0100] (Absorption loss amount X-Y ) [%] = 100 - (transmittance under the condition of an incident angle of 5 degrees) - (reflectance under the condition of an incident angle of 5 degrees)

[0101] (i-14) The average value of the absorption loss amount in the wavelength range of 700 nm to 800 nm 700-800 Is 25% or more;

[0102] (i-15) The absorption loss amount in the wavelength range of 850 nm to 1000 nm 850-1000The average value is above 17%.

[0103] The greater the absorption loss, the more the light in that wavelength range is absorbed.

[0104] Satisfying the spectral characteristics (i-14) to (i-15) means that the proportion of the spectral characteristics formed by absorption loss is above a certain level. The greater this proportion, the more the effect of reducing the variation in spectral characteristics under the conditions of vertically incident light and obliquely incident light can be expected.

[0105] Absorption loss 700-800 The average value is more preferably above 26.5%, and further preferably above 28%.

[0106] Absorption loss 850-1000 The average value is more preferably above 18%, and further preferably above 20%.

[0107] The spectral characteristics (i-14) to (i-15) can be achieved, for example, by using a near-infrared absorbing dye having a maximum absorption wavelength in the wavelength range of 700 nm to 800 nm.

[0108] <Near-infrared absorbing glass (fluorophosphate glass)>

[0109] The near-infrared absorbing glass in the filter of the present embodiment is a fluorophosphate glass containing P, Cu, and F (hereinafter, also referred to as the fluorophosphate glass of the present embodiment or simply as fluorophosphate glass or glass).

[0110] By containing Cu in the fluorophosphate glass containing P and F, it is possible to suppress the light transmittance in the near-infrared region to a low level while maintaining a high light transmittance in the visible light region. In addition, by containing F in the glass, the weather resistance such as moisture resistance can be improved.

[0111] The respective components that can constitute the fluorophosphate glass of the present embodiment and their suitable contents will be described below. In the present specification, unless otherwise specified, the contents of the respective components and the total content are in mass%. In addition, the light transmittance of the glass of the present embodiment includes the reflection characteristics of the glass surface (that is, it is not the internal transmittance of the glass).

[0112] In the fluorophosphate glass of the present embodiment, P is contained in the form of 5+ P.

[0113] P 5+ is the main component for forming the fluorophosphate glass and is an essential component for improving the near-infrared cut-off property. If the content of P 5+ is 30% or more, its effect can be sufficiently obtained. If P 5+If the content is less than 70%, problems such as the glass becoming unstable or the weather resistance decreasing are less likely to occur. Therefore, P 5+ The content is preferably 30% to 70%. More preferably, it is 31% or more, further preferably 32% or more, further more preferably 33% or more. Additionally, more preferably, it is 60% or less, further preferably 50% or less, further more preferably 45% or less, and most preferably 43% or less.

[0114] It should be noted that as the raw material of P 5+ Considering the viewpoints of suppressing the erosion of platinum crucibles and suppressing the volatilization of components, phosphoric acid or its salts are preferably used.

[0115] In the fluoro-phosphoric acid glass of the present embodiment, F is contained in the form of F -

[0116] F - is an essential component for stabilizing the glass and improving the weather resistance. In this specification, when the component elements other than F contained in the glass are set to 100% by mass, the content of F contained in the glass is expressed as an external addition ratio. - - The content of F - is preferably 5% to 70% in terms of the external addition ratio. If the content of F - is 5% or more in terms of the external addition ratio, the weather resistance effect can be sufficiently obtained. When the content of F - is 70% or less in terms of the external addition ratio, problems such as a decrease in the transmittance of light in the visible light region, or a decrease in mechanical properties such as strength, hardness, and elastic modulus, or an increase in the ultraviolet transmittance are less likely to occur. The content of F - is more preferably 6% or more in terms of the external addition ratio, further preferably 8% or more in terms of the external addition ratio, further more preferably 8.5% or more in terms of the external addition ratio, most preferably 10% or more in terms of the external addition ratio. Additionally, more preferably, it is 60% or less in terms of the external addition ratio, further preferably 50% or less in terms of the external addition ratio, further more preferably 40% or less in terms of the external addition ratio, and most preferably 25% or less in terms of the external addition ratio.

[0117] In the fluoro-phosphoric acid glass of the present embodiment, Cu is contained in the form of Cu + or Cu 2+ , but the content in the case where all exist in the form of Cu 2+ is described in this application specification.

[0118] Cu 2+ is an essential component for near-infrared cutoff. The content of Cu 2+ is preferably 1% to 20%. If Cu 2+If the content is 1% or more, its effects and the effect of improving the light transmittance in the visible light region of the glass obtained when added together with Mo can be fully obtained. Additionally, if Cu 2+ has a content of 20% or less, problems such as devitrification foreign matter generation in the glass or a decrease in the light transmittance in the visible light region are less likely to occur. Cu 2+ The content is more preferably 4.5% or more, further preferably 6% or more, still further preferably 7.5% or more, and most preferably 7.8% or more. Additionally, it is more preferably 18% or less, further preferably 16% or less, still further preferably 13% or less, and most preferably 12% or less.

[0119] In addition, the total Cu amount is the total amount of Cu in mass% including monovalent, divalent, and other existing valences. When the glass of this embodiment (excluding the content of F - ) is set to 100% by mass, in this glass, the content range of the total Cu amount is preferably 1% to 20% by mass. When the total Cu amount is 1% or more, the effect of near-infrared cutoff can be fully obtained even when reducing the plate thickness of the glass. Additionally, when the total Cu amount is 20% or less, a decrease in the transmittance in the visible light region can be suppressed. The total Cu amount is more preferably 4.5% or more, further preferably 6% or more, still further preferably 7.5% or more, and most preferably 9% or more. Additionally, it is more preferably 18% or less, further preferably 16% or less, still further preferably 13% or less, and most preferably 11.5% or less. It should be noted that the content of Cu + can be determined within the range of 0.01% to 4.0% in (Cu + / total Cu amount)×100[%.]

[0120] Al 3+ is a component that forms the glass and is a component for improving the strength of the glass, improving the weather resistance of the glass, etc. When the glass contains Al 3+ , if the content of Al 3+ is 2% or more, its effects can be fully obtained. If the content of Al 3+ is 20% or less, problems such as the glass becoming unstable or a decrease in near-infrared cutoff performance are less likely to occur. The content of Al 3+ is preferably 0% to 20%. The content of Al 3+ is more preferably 2% or more, further preferably 3% or more, still further preferably 3.5% or more, and most preferably 5% or more. Additionally, it is more preferably 18% or less, further preferably 15% or less, still further preferably 13% or less, and most preferably 10% or less.

[0121] It should be noted that as Al3+ The raw materials can be AlF3, Al2O3, Al(OH)3, etc. Among them, the melting temperature is not easily increased, the unmelted material is not easily generated, and F - Considering the problem that the amount of feed is reduced and the glass becomes unstable, it is preferred to use AlF3.

[0122] Li + It is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. + The content of Li is preferably 0% to 20%. + When the content of Li is less than 20%, problems such as glass instability or reduction in near-infrared cutoff properties are less likely to occur. + The content is more preferably 18% or less, further preferably 15% or less, further preferably 12% or less, and most preferably 10% or less.

[0123] In the fluorophosphate glass of this embodiment, Na + Contains Na in the form of

[0124] Na + It is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. In addition, when glass contains Na + , the effect of increasing the transmittance of light in the visible light region of the glass obtained by adding Mo together can be fully obtained. The mechanism is explained below. Cu in fluorophosphate glass + There are oxygen ions around the Cu ions, which have negative charges. The electric field generated by the negative charges has the effect of hindering the + with Mo 6+ The electrons (e - ) + →Cu 2+ +e - ) and (Mo 6+ +e - →Mo 5+ ) by the presence of Na in fluorophosphate glass + , the negative charge of the oxygen ion is replaced by Na + The positive charge carried by the Cu is neutralized. As a result, the Cu + with Mo 5+ The electron transfer between Cu and Cu has the light absorption characteristics in the visible light region. + The presence ratio is reduced and the light transmittance in the visible light region is improved.

[0125] In glass containing Na + In the case of +The content of [substance] is preferably 0.1% to 25%. If the content of Na + is below 25%, the glass is not likely to become unstable. The content of Na + is more preferably 0.5% or more, further preferably 1% or more, further more preferably 2% or more, most preferably 3% or more. Additionally, it is more preferably 20% or less, further preferably 18% or less, further more preferably 14% or less, most preferably 10% or less.

[0126] K + is a component that has effects such as reducing the melting temperature of the glass and reducing the liquidus temperature of the glass. As the content of K + , it is preferably 0% to 25%. If the content of K + is below 25%, the glass is not likely to become unstable, so it is preferred. The content of K + is more preferably 23% or less, further preferably 20% or less, further more preferably 18% or less, most preferably 15% or less.

[0127] R + (selected from one or more components of Li + , Na + , and K + ) is a component for reducing the melting temperature of the glass, reducing the liquidus temperature of the glass, stabilizing the glass, etc. If the total amount of R + , that is, the total amount of Li + , Na + , and K + (ΣR + ) is 0.1% or more, its effects can be fully obtained. If the total amount of R + , that is, the total amount of Li + , Na + , and K + (ΣR + ) is 30% or less, the glass is not likely to become unstable, so it is preferred. Therefore, the content of ΣR + is preferably 0.1% to 30%. It is more preferably 1% or more, further preferably 3% or more, further more preferably 5% or more, most preferably 8% or more. Additionally, it is more preferably 28% or less, further preferably 27% or less, further more preferably 26% or less, most preferably 25% or less.

[0128] Mg 2+ is a component for reducing the melting temperature of the glass, reducing the liquidus temperature of the glass, stabilizing the glass, increasing the strength of the glass, etc. As the content of Mg 2+ , it is preferably 0% to 10%. If the content of Mg 2+If the content is 10% or less, problems such as the glass becoming unstable or the near-infrared cut-off property decreasing are less likely to occur. Mg 2+ The content is more preferably 8% or less, further preferably 6% or less, still further preferably 5% or less, and most preferably 3% or less.

[0129] Ca 2+ is a component for reducing the melting temperature of the glass, reducing the liquidus temperature of the glass, stabilizing the glass, increasing the strength of the glass, etc. As Ca 2+ content, it is preferably 0% to 20%. If the Ca 2+ content is 20% or less, problems such as the glass becoming unstable or the near-infrared cut-off property decreasing are less likely to occur. Ca 2+ content is more preferably 0.1% or more, further preferably 1% or more, still further preferably 2% or more, most preferably 3% or more. Additionally, it is more preferably 18% or less, further preferably 15% or less, still further preferably 10% or less, and most preferably 6% or less.

[0130] Sr 2+ is a component for reducing the melting temperature of the glass, reducing the liquidus temperature of the glass, stabilizing the glass, etc. As Sr 2+ content, it is preferably 0% to 30%. If the Sr 2+ content is 30% or less, problems such as the glass becoming unstable or the near-infrared cut-off property decreasing are less likely to occur. Sr 2+ content is more preferably 0.1% or more, further preferably 1% or more, still further preferably 3% or more, most preferably 5% or more. Additionally, it is more preferably 25% or less, further preferably 20% or less, still further preferably 15% or less, and most preferably 10% or less.

[0131] Ba 2+ is a component for reducing the melting temperature of the glass, reducing the liquidus temperature of the glass, stabilizing the glass, etc. As Ba 2+ content, it is preferably 0% to 40%. If the Ba 2+ content is 40% or less, problems such as the glass becoming unstable or the near-infrared cut-off property decreasing are less likely to occur. Ba 2+ content is more preferably 0.1% or more, further preferably 5% or more, still further preferably 10% or more, most preferably 15% or more. Additionally, it is more preferably 35% or less, further preferably 30% or less, still further preferably 25% or less, and most preferably 23% or less.

[0132] R 2+ (selected from Mg 2+ 、Ca 2+ 、Sr2+ and Ba 2+ One or more of the above components) are components for lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, stabilizing the glass, etc. If R 2+ The total content of, that is, Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ The total content of (ΣR 2+ ) is 10% or more, its effect can be fully obtained. If the total content of R 2+ , that is, Mg 2+ , Ca 2+ , Sr 2+ and Ba 2 + The total content of (ΣR 2+ ) is 45% or less, the glass is not likely to become unstable. Therefore, the content of ΣR 2+ is preferably 10% to 45%. More preferably 15% or more, further preferably 20% or more, further more preferably 23% or more, most preferably 25% or more. Additionally, more preferably 40% or less, further preferably 35% or less, further more preferably 33% or less, most preferably 30% or less.

[0133] Zn 2+ Has the effects of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, etc. The content of Zn 2+ is preferably 0% to 30%. If the content of Zn 2+ is 30% or less, problems such as the glass becoming unstable, the meltability of the glass deteriorating, or the near-infrared cut-off property decreasing are less likely to occur. The content of Zn 2+ is more preferably 20% or less, further preferably 15% or less, further more preferably 10% or less, most preferably 5% or less.

[0134] Rb + Is a component having the effects of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, etc. As the content of Rb + , it is preferably 0% to 10%. If the content of Rb + is 10% or less, the glass is not likely to become unstable. The content of Rb + is more preferably 8% or less, further preferably 6% or less, further more preferably 4% or less, most preferably 2% or less.

[0135] Cs + Is a component having the effects of lowering the melting temperature of the glass, lowering the liquidus temperature of the glass, etc. As the content of Cs + , it is preferably 0% to 10%. If the content of Cs +If the content of Cs is 10% or less, the glass is not likely to become unstable. + The content of Cs is more preferably 8% or less, further preferably 6% or less, still further preferably 4% or less, and most preferably 2% or less.

[0136] In order to stabilize the glass, B may be contained in the range of 20% or less. 3+ If 3+ the content of B is 20% or less, problems such as deterioration of the weather resistance of the glass or reduction of the near-infrared ray cut-off property are not likely to occur. 3+ The content of B is more preferably 15% or less, further preferably 10% or less, still further preferably 8% or less, and most preferably 5% or less.

[0137] Mo is contained in the form of Mo 5+ or Mo 6+ , but the content in the case where all exist in the form of Mo 6+ is described in the specification of the present application.

[0138] Mo 6+ is a component for increasing the transmittance of light in the visible light region of the glass.

[0139] It is known that Mo exists in the glass in the form of Mo 6+ (hexavalent). However, when Mo and Cu are added to the phosphate glass at the same time, Cu + in the glass emits electrons (e - ) to become Cu 2+ (Cu + →Cu 2+ +e - ), and Mo 6+ accepts the electrons emitted by Cu + to become Mo 5 + (pentavalent) (Mo 6+ +e - →Mo 5+ ). As a result, the proportion of the existence of Cu + (monovalent) having an absorption characteristic in the vicinity of 300 nm to 600 nm in wavelength decreases, and the transmittance of light in the wavelength range of 400 nm to 540 nm increases. It is considered that Mo 5+ has a characteristic of absorbing light having a wavelength of about 400 nm, and it is considered that the transmittance of light having a wavelength of about 400 nm does not increase for this reason.

[0140] The content of Mo is preferably 0% to 4%. When Mo 6+ is contained, its content is preferably 0.01% to 4%. If Mo 6+ 6 + ​If the content is 0.01% or more, the effect of improving the light transmittance in the visible light region of the glass can be fully obtained. In addition, if Mo 6+ has a content of 4% or less, problems such as a decrease in near-infrared cut-off property or the generation of devitrified foreign substances in the glass are less likely to occur. The content of Mo 6+ is more preferably 0.05% or more, further preferably 0.1% or more, still further preferably 0.2% or more, and most preferably 0.3% or more. In addition, it is more preferably 3.5% or less, further preferably 3% or less, still further preferably 2% or less, and most preferably 1% or less.

[0141] In the case of containing Mo 6+ , the content ratio of Mo 6+ to Cu 2+ (Mo 6+ / Cu 2+ ) is preferably 0.01 to 0.39 on a mass basis. By the content ratio of Mo 6+ to Cu 2+ (Mo 6+ / Cu 2+ ) being 0.01 or more, the absorption of light with wavelengths in the visible light region generated by Cu + can be sufficiently suppressed, and the absorption of light with wavelengths in the near-infrared region generated by Cu 2+ can be sufficiently promoted. In addition, by the content ratio of Mo 6+ to Cu 2+ (Mo 6+ / Cu 2+ ) being 0.39 or less, a decrease in the transmittance in the visible light region caused by Mo 5+ can be suppressed. The content ratio of Mo 6+ to Cu 2+ (Mo 6+ / Cu 2+ ) is more preferably 0.02 or more, further preferably 0.03 or more, still further preferably 0.05 or more, and most preferably 0.1 or more. In addition, it is more preferably 0.35 or less, further preferably 0.3 or less, still further preferably 0.25 or less, and most preferably 0.2 or less.

[0142] In order to improve the weather resistance of the glass, the fluoro-phosphate glass of the present embodiment may contain SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, Nb2O5 within the range of 10% or less. If the content of these components is 10% or less, problems such as devitrification foreign matter generation or reduction of near-infrared ray cut-off property in the glass are less likely to occur. The content of these components is preferably 4% or less, more preferably 3% or less, further preferably 2% or less, and even more preferably 1% or less.

[0143] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MnO2, and CoO are all components that reduce the transmittance of light in the visible light region by existing in the glass. Therefore, it is preferable that these components are substantially not contained in the glass. Here, substantially not containing in the glass means not containing except for inevitable impurities, and means not actively adding the component. Specifically, it means that the content rate of these components is each about 100 mass ppm or less in the glass.

[0144] The thermal expansion coefficient of the fluoro-phosphate glass of the present embodiment in the range of 30 °C to 300 °C is preferably 60×10 -7 / °C to 180×10 -7 / °C, more preferably 65×10 -7 / °C to 175×10 -7 / °C, further preferably 70×10 -7 / °C to 170×10 -7 / °C.

[0145] The fluoro-phosphate glass in the filter of the present embodiment preferably satisfies all of the following spectral characteristics (ii-1) to (ii-3).

[0146] (ii-1) The wavelength IR_T when the transmittance is 50% under the condition that the incident angle is 0 degree 50(0deg) is in the range of 590 nm to 640 nm;

[0147] (ii-2) The transmittance T at a wavelength of 700 nm under the condition that the incident angle is 0 degree 700(0deg) is 25% or less;

[0148] (ii-3) The average transmittance T at wavelengths of 700 nm to 800 nm under the condition that the incident angle is 0 degree 700-800(0deg)AVE is 10% or less.

[0149] As shown in the spectral characteristics (ii-1) to (ii-3), the near-infrared absorbing glass allows visible light to transmit, the region of 590 nm to 640 nm is the boundary between the transmission band and the absorption band, and it becomes an absorption band from 700 nm and above. Thus, a filter with excellent visible light transmittance and near-infrared light shielding property can be obtained.

[0150] Wavelength IR_T 50(0deg) More preferably, it is in the range of 590 nm to 630 nm, and still more preferably in the range of 590 nm to 624 nm.

[0151] Transmittance T 700(0deg) More preferably, it is 20% or less, still more preferably 15% or less, and particularly preferably 10% or less.

[0152] Average transmittance T 700-800(0deg)AVE More preferably, it is 9.8% or less, and still more preferably 9.7% or less.

[0153] The fluoro-phosphate glass in the filter of this embodiment preferably satisfies the following spectral characteristic (ii-4). Thus, a filter with excellent shielding property for near-infrared light of 800 nm and above can be obtained.

[0154] (ii-4) The average transmittance T of wavelengths from 800 nm to 1200 nm under the condition that the incident angle is 0 degree 800-1200(0deg)AVE Is 10% or less.

[0155] Average transmittance T 800-1200(0deg)AVE More preferably, it is 8% or less, and still more preferably 6% or less.

[0156] The thickness of the fluoro-phosphate glass in the filter of this embodiment is preferably 0.5 mm or less, and more preferably 0.4 mm or less. In addition, from the viewpoint of maintaining the strength of the element, the thickness is preferably 0.1 mm or more, and more preferably 0.15 mm or more.

[0157] <Dielectric multilayer film>

[0158] The filter of this embodiment includes a dielectric multilayer film 1 and a dielectric multilayer film 2. At least one of the dielectric multilayer films is preferably designed as a reflection film (hereinafter also referred to as "NIR reflection film") that reflects a part of near-infrared light. The other dielectric multilayer film may also be designed as a reflection film having a reflection region other than the near-infrared region, or an antireflection film.

[0159] The NIR reflection film preferably has, for example, a wavelength selectivity that allows visible light to transmit, allows near-infrared light in the transmission region of the absorption layer to transmit, and mainly reflects near-infrared light other than the near-infrared light in the transmission region of the absorption layer.

[0160] As shown in the spectral characteristics (i-5) and spectral characteristics (i-7) of the above-mentioned filter, at least one of the dielectric multilayer films is preferably a reflective film having reflective characteristics in the near-infrared light region with a wavelength of 850 nm to 1200 nm, and this characteristic is used to shield light.

[0161] By combining the reflective characteristics in this specific wavelength range with the absorption characteristics of a near-infrared absorbing dye having a maximum absorption wavelength in the range of 740 nm to 800 nm and a fluoro-phosphate glass having a main absorption wavelength of 700 nm to 1200 nm, it is possible to shield light in the near-infrared light region with a wavelength of 700 nm to 1200 nm over a wide range.

[0162] On the other hand, as shown in the spectral characteristics (i-6) and spectral characteristics (i-8) of the above-mentioned filter, the dielectric multilayer film as this reflective film preferably has little change in the reflective characteristics in the visible light region. Thereby, a filter can be obtained in which the spectral characteristics in the visible light region are not easily changed according to the incident angle and the ripple is reduced.

[0163] As can be seen from the above, at least one dielectric multilayer film is preferably designed to be a reflective film that does not reflect visible light and reflects near-infrared light (wavelength 800 nm to 1200 nm) under the condition that the incident angle of light is 0 degrees to 60 degrees.

[0164] As shown in the spectral characteristics (i-9) to spectral characteristics (i-12) of the above-mentioned filter, another dielectric multilayer film is preferably designed to be an antireflection layer having small reflective characteristics in both the visible light region and the near-infrared light region.

[0165] The dielectric multilayer film is constituted of, for example, a dielectric multilayer film obtained by laminating dielectric films having different refractive indices. More specifically, examples include: a low-refractive-index dielectric film (low-refractive-index film), a medium-refractive-index dielectric film (medium-refractive-index film), a high-refractive-index dielectric film (high-refractive-index film), and a dielectric multilayer film obtained by laminating two or more of these dielectric films.

[0166] The high-refractive-index film preferably has a refractive index of 1.6 or more at a wavelength of 500 nm, more preferably 1.8 to 2.5, and particularly preferably 2.2 to 2.5. As materials for the high-refractive-index film, for example, Ta2O5, TiO2, TiO, and Nb2O5 can be cited. As other commercially available products, OS50 (Ti3O5), OS10 (Ti4O7), OA500 (a mixture of Ta2O5 and ZrO2), OA600 (a mixture of Ta2O5 and TiO2), etc., manufactured by Canon Optron Co., Ltd. can be cited. Among them, TiO2 is preferably used in consideration of film formability, reproducibility of refractive index, stability, etc.

[0167] The medium refractive index film preferably has a refractive index of 1.6 or more and less than 2.2 at a wavelength of 500 nm. As materials for the medium refractive index film, for example, ZrO2, Nb2O5, Al2O3, HfO2 can be cited; OM-4, OM-6 (a mixture of Al2O3 and ZrO2), OA-100 sold by Canon Optron Co., Ltd.; H4, M2 (aluminum oxide - lanthanum oxide) sold by Merck Co., etc. Among them, from the aspects of film formation property, reproducibility of refractive index, stability, etc., Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred.

[0168] The low refractive index film preferably has a refractive index of less than 1.6 at a wavelength of 500 nm, and more preferably 1.38 to 1.5. As materials for the low refractive index film, for example, SiO2, SiO x N y 、MgF2, etc. As other commercially available products, S4F, S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Co., Ltd. can be cited. Among them, from the aspects of reproducibility of film formation property, stability, economy, etc., SiO2 is preferred.

[0169] For the dielectric multilayer film, [the sum T(H) of QWOT of the dielectric film with a relatively high refractive index] / [the sum T(L) of QWOT of the dielectric film with a relatively low refractive index] is preferably 1.6 or more. Thus, it is easy to obtain a dielectric multilayer film having the above spectral characteristics that satisfies near-infrared light with a reflection wavelength of 800 nm to 1100 nm and suppresses the reflection of visible light. In addition, it is preferred that at least the dielectric multilayer film laminated on the light incident side satisfies this ratio relationship.

[0170] It should be noted that here, QWOT (Quarter Wave Optical Thickness) refers to the optical film thickness of λ / 4 of the wavelength, which is calculated from the physical film thickness by the following formula.

[0171] QWOT = physical film thickness / center wavelength (500 nm) × 4 × refractive index at a wavelength of 500 nm

[0172] In the case where the dielectric multilayer film is a laminate of a low refractive index film and a high refractive index film, the sum T(H) of QWOT is the sum of QWOT of the high refractive index film, and the sum T(L) of QWOT is the sum of QWOT of the low refractive index film.

[0173] In addition, in the case where the dielectric multilayer film is a laminate of a low refractive index film and a medium refractive index film, the sum T(H) of QWOT is the sum of QWOT of the medium refractive index film, and the sum T(L) of QWOT is the sum of QWOT of the low refractive index film.

[0174] In the case where the dielectric multilayer film is a laminate of a medium refractive index film and a high refractive index film, the total sum T(H) of the QWOTs is the total sum of the QWOTs of the high refractive index films, and the total sum T(L) of the QWOTs is the total sum of the QWOTs of the medium refractive index films.

[0175] In addition, the dielectric multilayer film is preferably a multilayer film obtained by alternately laminating 10 or more layers each of the H2 layer and the M2 layer defined below. H2 layer: a single layer having a refractive index of 1.8 or more and 2.5 or less and a QWOT of 1.1 or more and 3.5 or less, M2 layer: a single layer or a multilayer existing between two H2 layers and having a total sum of QWOTs of 1.2 or more and 1.8 or less.

[0176] The above specific laminated structure is a structure obtained by alternately laminating 10 or more layers of a single layer (H2 layer) having a large refractive index and optical film thickness and a layer (M2 layer) having a total optical film thickness within a specified range. With this structure, it is easy to obtain a dielectric multilayer film that reflects near-infrared light with a reflection wavelength of 800 nm to 1200 nm and has a low reflectance of visible light.

[0177] It should be noted that as long as the M2 layer satisfies the specified optical film thickness, it can be a single layer or a multilayer, but from the viewpoint of obtaining smoother spectral characteristics, it is preferably composed of multiple layers. In addition, the minimum value of the film thickness of the single layer is preferably 5 nm or more, more preferably 10 nm or more. In addition, the refractive index of the dielectric film constituting the M2 layer is preferably the same as or lower than the refractive index of the H2 layer.

[0178] The dielectric multilayer film having the above specific laminated structure is preferably at least a dielectric multilayer film designed as a reflective film.

[0179] In the case where the dielectric multilayer film designed as a reflective film has the above laminated structure, the layer closest to the near-infrared absorbing glass in the H2 layer and the M2 layer is preferably the H2 layer. The H2 layer closest to the near-infrared absorbing glass can be directly laminated on the near-infrared absorbing glass, or there can be other layers that belong neither to the H2 layer nor to the M2 layer between the H2 layer closest to the near-infrared absorbing glass and the near-infrared absorbing glass.

[0180] As the dielectric multilayer film designed as a reflective film, the total number of laminated layers of the dielectric multilayer film is preferably 10 or more, more preferably 20 or more, and further preferably 30 or more. However, when the total number of laminated layers increases, warping or the like occurs or the film thickness increases, so the total number of laminated layers is preferably 110 or less, more preferably 80 or less, and even more preferably 60 or less.

[0181] In addition, the film thickness (physical film thickness) of the dielectric multilayer film designed as a reflective film is preferably 1 μm to 6 μm as a whole.

[0182] When a filter is installed in an imaging device, the dielectric multilayer film on the sensor side is usually preferably designed as an antireflection layer. The total number of stacked layers of the dielectric multilayer film designed as an antireflection layer is preferably 40 layers or less, more preferably 30 layers or less, still more preferably 20 layers or less, and further preferably 6 layers or more.

[0183] In addition, the film thickness (physical film thickness) of the dielectric multilayer film designed as an antireflection layer is preferably 0.2 μm to 1.0 μm as a whole.

[0184] In the formation of the dielectric multilayer film, for example, vacuum film-forming processes such as CVD method, sputtering method, and vacuum evaporation method can be used; wet film-forming processes such as spraying method and dipping method can also be used.

[0185] When a filter is installed in an imaging device, usually the dielectric multilayer film stacked on the glass surface is made the lens side, and the dielectric multilayer film stacked on the resin film surface is made the sensor side. Therefore, the filter of the present embodiment is preferably installed in such a manner that the dielectric multilayer film 1 is the lens side and the dielectric multilayer film 2 is the sensor side.

[0186] <Resin film>

[0187] The resin film in the filter of the present embodiment contains a resin and a near-infrared absorbing pigment. Here, the resin refers to the resin constituting the resin film.

[0188] As the near-infrared absorbing pigment, a pigment having a maximum absorption wavelength in the wavelength range of 740 nm to 800 nm in the resin is preferably used. By having a maximum absorption wavelength in the range of 740 nm to 800 nm, the near-infrared light absorption region of the fluorophosphate glass containing Cu or the like becomes the short-wavelength side, so that the spectral characteristics of the pigment can be more effectively utilized when combined with the glass.

[0189] As the near-infrared absorbing pigment, for example, at least one selected from the group consisting of cyanine pigments, phthalocyanine pigments, squarylium salt pigments, naphthalocyanine pigments, and diiminium pigments can be mentioned, and they can be used alone or in combination of multiple kinds. Among them, from the viewpoint of being able to sharply absorb the region of 740 nm to 800 nm and easily exerting the effects of the present invention, squarylium salt pigments and cyanine pigments are preferred.

[0190] The content of the near-infrared absorbing pigment in the resin film is preferably 0.1 part by mass to 30 parts by mass, more preferably 0.1 part by mass to 20 parts by mass, relative to 100 parts by mass of the resin. It should be noted that in the case of combining two or more compounds, the above content is the sum of the respective compounds.

[0191] The resin film may contain other pigments, such as ultraviolet light-absorbing pigments, within a range that does not impair the effects of the present invention.

[0192] Examples of the ultraviolet light-absorbing pigments include: azole pigments, merocyanine pigments, cyanine pigments, naphthalene dicarboximide pigments, diazole pigments, azine pigments, oxazolidine pigments, naphthalenedicarboxylic acid pigments, styryl pigments, anthracene pigments, cyclic carbonyl pigments, triazole pigments, etc. Among them, merocyanine pigments are particularly preferred. In addition, one kind can be used alone, or two or more kinds can be used in combination.

[0193] As the resin, there is no limitation as long as it is a transparent resin, and one or more transparent resins selected from polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins can be used. These resins can be used alone, or two or more kinds can be mixed and used.

[0194] From the viewpoints of the spectral characteristics, glass transition temperature (Tg), and adhesiveness of the resin film, one or more resins selected from polyimide resins, polycarbonate resins, polyester resins, and acrylic resins are preferred.

[0195] In the case of using multiple pigments, these pigments can be contained in the same resin film, or can be separately contained in different resin films.

[0196] The resin film can be formed by the following method: preparing a coating liquid by dissolving or dispersing the pigment, the resin or the raw material components of the resin, and each component blended as required in a solvent, coating the coating liquid on a support and drying it, and further curing it as required. The support at this time can be the near-infrared absorbing glass for this filter, or can be a peelable support used only when forming the resin film. In addition, the solvent can be a dispersion medium capable of stably dispersing or a solvent capable of dissolving.

[0197] In addition, in order to improve the voids caused by minute bubbles, the depressions caused by the adhesion of foreign substances, etc., and the shrinkage holes in the drying process, the coating liquid can contain a surfactant. In addition, in the coating of the coating liquid, for example, dip coating, casting coating, or spin coating can be used. The above coating liquid is coated on the support and then dried to form a resin film. In addition, in the case where the coating liquid contains the raw material components of a transparent resin, further curing treatments such as heat curing and light curing are performed.

[0198] Alternatively, the resin film can also be formed into a film shape by extrusion molding. The obtained film-shaped resin film is laminated on the phosphate glass and integrated by thermocompression bonding or the like, whereby a substrate can be manufactured.

[0199] The filter may have one resin film or two or more resin films. When there are two or more resin films, each layer may have the same composition or different compositions. Additionally, when there are two or more resin films, they may all be laminated on the same main surface side of the near-infrared absorbing glass, or may be laminated on different main surface sides respectively.

[0200] From the viewpoints of the in-plane film thickness distribution within the coated substrate and the appearance quality, the thickness of the resin film is 10 μm or less, preferably 5 μm or less. Additionally, from the viewpoint of exhibiting the desired spectral characteristics with an appropriate pigment concentration, the thickness of the resin film is preferably 0.5 μm or more. It should be noted that when the filter has two or more resin films, the total thickness of each resin film is preferably within the above range.

[0201] The above resin film in the filter of the present embodiment preferably satisfies all of the following spectral characteristics (iv-1) to (iv-4).

[0202] (iv-1) The average internal transmittance T at a wavelength of 440 nm to 600 nm under the condition that the incident angle is 0 degrees (in)440-600(0deg)AVE is 90% or more;

[0203] (iv-2) The wavelength IR_T when the internal transmittance is 50% under the condition that the incident angle is 0 degrees (in)50(0deg) is in the range of 630 nm to 645 nm;

[0204] (iv-3) In the wavelength range of 500 nm to 700 nm, the absolute value of the difference between the wavelength IR_T when the internal transmittance is 70% under the condition that the incident angle is 0 degrees (in)70(0deg) and the wavelength IR_T when the transmittance is 20% under the condition that the incident angle is 0 degrees (in)20(0deg) is 60 nm or less;

[0205] (iv-4) The average internal transmittance T at a wavelength of 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE is 5% or less.

[0206] For the resin film, as shown in the spectral characteristic (iv-1), the visible light transmittance is high. As shown in the spectral characteristic (iv-2), the wavelength range of 630 nm to 645 nm is the boundary region between the transmission region and the absorption region. As shown in the spectral characteristic (iv-3), the absorption characteristic in the boundary region is steep. As shown in the spectral characteristic (iv-4), the resin film has high shielding property for near-infrared light with wavelengths in the range of 700 nm to 800 nm.

[0207] Average internal transmittance T (in)440-600(0deg)AVE More preferably, it is 90.5% or more, and further preferably 91% or more.

[0208] Wavelength IR_T (in)50(0deg) More preferably, it is in the range of 632 nm to 640 nm, and further preferably in the range of 634 nm to 640 nm.

[0209] The absolute value of the difference in (iv-3) is more preferably 57 nm or less, and further preferably 55 nm or less.

[0210] Average internal transmittance T (in)700-800(0deg)AVE More preferably, it is 4% or less, and further preferably 3% or less.

[0211] In addition, the substrate having the above-mentioned near-infrared absorbing glass and resin film preferably satisfies all of the following spectral characteristics (iii-1) to (iii-3).

[0212] (iii-1) The average internal transmittance T of wavelengths from 440 nm to 600 nm under the condition that the incident angle is 0 degrees (in)440-600(0deg)AVE is 75% or more;

[0213] (iii-2) The average internal transmittance T of wavelengths from 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE is 1.2% or less;

[0214] (iii-3) The average internal transmittance T of wavelengths from 800 nm to 1000 nm under the condition that the incident angle is 0 degrees (in)800-1000(0deg)AVE is 5% or less.

[0215] As shown in the spectral characteristics (iii-1) to (iii-3), the substrate formed by combining glass and near-infrared absorbing pigment has high visible light transmittance and high near-infrared absorption characteristics in the wavelength range of 700 nm to 1000 nm.

[0216] Average internal transmittance T (in)440-600(0deg)AVE More preferably, it is 76% or more, and further preferably 77% or more.

[0217] Average internal transmittance T (in)700-800(0deg)AVE More preferably, it is 1.1% or less, and further preferably 1.05% or less.

[0218] Average internal transmittance T (in)800-1000(0deg)AVE More preferably, it is 4.5% or less, and still more preferably 4.0% or less.

[0219] The filter of the present embodiment may include, for example, a constituent element (layer) that generates absorption such as inorganic fine particles that control the transmission and absorption of light in a specific wavelength range as other constituent elements. Specific examples of the inorganic fine particles include: ITO (Indium Tin Oxides), ATO (Antimony-doped Tin Oxides), cesium tungstate, lanthanum boride, etc. ITO fine particles and cesium tungstate fine particles can be used when shielding of this infrared light is required because they have high visible light transmittance and light absorptivity in a wide range of infrared wavelength regions greater than 1200 nm.

[0220] When the filter of the present embodiment is used in an imaging device such as a digital camera, for example, an imaging device with excellent color reproducibility can be provided. The imaging device includes a solid-state imaging element, an imaging lens, and the filter of the present embodiment. The filter of the present embodiment can be disposed, for example, between the imaging lens and the solid-state imaging element or directly adhered to the solid-state imaging element, imaging lens, etc. of the imaging device through an adhesive layer for use.

[0221] As described above, the following filters and the like are disclosed in this specification.

[0222] [1] A filter, the filter sequentially includes a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2, wherein,

[0223] The resin film contains a near-infrared absorbing pigment and a resin,

[0224] The near-infrared absorbing glass is a fluorophosphate glass containing P, Cu, and F,

[0225] The filter satisfies all of the following spectral characteristics (i-1) to (i-5):

[0226] (i-1) The average transmittance T at a wavelength of 440 nm to 600 nm under the condition that the incident angle is 0 degrees 440-600(0deg)AVE And the average transmittance T at a wavelength of 440 nm to 600 nm under the condition that the incident angle is 60 degrees 440-600(60deg)AVE The absolute value of the difference is 15% or less;

[0227] (i-2) The average transmittance T 440-600(0deg)AVE Is 75% or more;

[0228] (i - 3) The wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) In the wavelength range of 580 nm to 640 nm;

[0229] (i - 4) The average transmittance T in the wavelength range of 700 nm to 800 nm under the condition that the incident angle is 0 degrees 700-800(0deg)AVE Is 1.1% or less;

[0230] (i - 5) The average transmittance T in the wavelength range of 800 nm to 1200 nm under the condition that the incident angle is 0 degrees 800-1200(0deg)AVE Is 5% or less.

[0231] [2] The filter according to [1], wherein the filter satisfies all of the following spectral characteristics (i - 6) to (i - 7):

[0232] (i - 6) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 in the wavelength range of 440 nm to 650 nm under the condition that the incident angle is 5 degrees 440-650(5deg)AVE Is 1.5% or less;

[0233] (i - 7) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 in the wavelength range of 850 nm to 1200 nm under the condition that the incident angle is 5 degrees 850-1200(5deg)AVE Is 60% or more.

[0234] [3] The filter according to [1] or [2], wherein the filter satisfies the following spectral characteristic (i - 8):

[0235] (i - 8) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 in the wavelength range of 440 nm to 650 nm under the condition that the incident angle is 60 degrees 440-650(60deg)AVE Is 10% or less.

[0236] [4] The filter according to any one of [1] to [3], wherein the filter satisfies all of the following spectral characteristics (i - 9) to (i - 10):

[0237] (i - 9) When the medium multilayer film 2 side is the incident direction, the average reflectance R2 in the wavelength range of 440 nm to 650 nm under the condition that the incident angle is 5 degrees 440-650(5deg)AVE Is less than 2.0%;

[0238] (i - 10) When the medium multilayer film 2 side is the incident direction, the average reflectance R2 in the wavelength range of 700 nm to 850 nm under the condition that the incident angle is 5 degrees 700-850(5deg)AVE Is 1.2% or less.

[0239] [5] The filter according to any one of [1] to [4], wherein the filter satisfies all of the following spectral characteristics (i-11) to (i-12):

[0240] (i-11) When the medium multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 60 degrees 440-650(60deg)AVE is less than 10%;

[0241] (i-12) When the medium multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 700 nm to 850 nm under the condition that the incident angle is 60 degrees 700-850(60deg)AVE is 8% or less.

[0242] [6] The filter according to any one of [1] to [5], wherein the filter satisfies the following spectral characteristic (i-13):

[0243] (i-13) When the medium multilayer film 1 side is the incident direction, the wavelength IR_R at which the reflectance is 50% under the condition that the incident angle is 5 degrees in the wavelength range of 750 nm to 900 nm 50(5deg) and the wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 5 degrees in the wavelength range of 580 nm to 640 nm 50(5deg) The absolute value of the difference is 160 nm or more.

[0244] [7] The filter according to any one of [1] to [6], wherein the filter satisfies all of the following spectral characteristics (i-14) to (i-15):

[0245] When the medium multilayer film 1 side is the incident direction, the absorption loss amount in the wavelength range of X nm to Y nm is defined as follows X-Y :

[0246] (Absorption loss amount X-Y ) [%] = 100 - (transmittance under the condition that the incident angle is 5 degrees) - (reflectance under the condition that the incident angle is 5 degrees)

[0247] (i-14) The average value of the absorption loss amount in the wavelength range of 700 nm to 800 nm 700-800 is 25% or more;

[0248] (i-15) The average value of the absorption loss amount in the wavelength range of 850 nm to 1000 nm 850-1000 is 17% or more.

[0249] [8] The filter according to any one of [1] to [7], wherein the thickness of the near-infrared absorbing glass is 0.4 mm or less,

[0250] The near-infrared absorbing glass satisfies all of the following spectral characteristics (ii-1) to (ii-3):

[0251] (ii-1) The wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) is in the range of 590 nm to 640 nm;

[0252] (ii-2) The transmittance T at a wavelength of 700 nm under the condition that the incident angle is 0 degrees 700(0deg) is 25% or less;

[0253] (ii-3) The average transmittance T in the wavelength range of 700 nm to 800 nm under the condition that the incident angle is 0 degrees 700-800(0deg)AVE is 10% or less.

[0254] [9] The filter according to any one of [1] to [8], wherein the substrate satisfies all of the following spectral characteristics (iii-1) to (iii-3):

[0255] (iii-1) The average internal transmittance T in the wavelength range of 440 nm to 600 nm under the condition that the incident angle is 0 degrees (in)440-600(0deg)AVE is 75% or more;

[0256] (iii-2) The average internal transmittance T in the wavelength range of 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE is 1.2% or less;

[0257] (iii-3) The average internal transmittance T in the wavelength range of 800 nm to 1000 nm under the condition that the incident angle is 0 degrees (in)800-1000(0deg)AVE is 5% or less.

[0258]

[10] The filter according to any one of [1] to [9], wherein the near-infrared absorbing pigment is a squarylium salt pigment having a maximum absorption wavelength in the range of 740 nm to 800 nm and is contained in the resin pigment.

[0259]

[11] The filter according to any one of [1] to

[10] , wherein the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-4):

[0260] (iv-1) The average internal transmittance T in the wavelength range of 440 nm to 600 nm under the condition that the incident angle is 0 degrees (in)440-600(0deg)AVE is 90% or more;

[0261] (iv-2) Wavelength IR_T at which the internal transmittance is 50% under the condition that the incident angle is 0 degrees (in)50(0deg) In the wavelength range of 630 nm to 645 nm;

[0262] (iv-3) Wavelength IR_T at which the internal transmittance is 70% under the condition that the incident angle is 0 degrees in the wavelength range of 500 nm to 700 nm (in)70(0deg) And the wavelength IR_T at which the transmittance is 20% under the condition that the incident angle is 0 degrees (in)20(0deg) The absolute value of the difference is 60 nm or less;

[0263] (iv-4) Average internal transmittance T in the wavelength range of 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE Is 5% or less.

[0264]

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

[11] , wherein the near-infrared absorbing glass is fluorophosphate glass, and the fluorophosphate glass contains, by mass%:

[0265] P 5+ : 30% to 70%

[0266] Al 3+ : 0% to 20%

[0267] Li + : 0% to 20%

[0268] Na + : 0% to 25%

[0269] K + : 0% to 25%

[0270] Mg 2+ : 0% to 10%

[0271] Ca 2+ : 0% to 20%

[0272] Sr 2+ : 0% to 30%

[0273] Ba 2+ : 0% to 40%

[0274] ΣR + : 0.1% to 30% (R + Is one or more components selected from Li + 、Na + And K + Among them)

[0275] ΣR2+ : 10% to 45% (R 2+ is selected from Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ and more than one of the components), and

[0276] Cu 2+ : 1% to 20%, and

[0277] when the component elements other than F contained in the glass are set to 100% by mass, based on the addition ratio, the fluoro-phosphate glass contains 5% to 70% by mass of F - . - .

[0278]

[13] An imaging device, wherein the imaging device includes the filter according to any one of [1] to

[12] .

[0279] Examples

[0280] Next, the present invention will be described more specifically by way of examples.

[0281] In the measurement of each spectral characteristic, a UV-visible spectrophotometer (manufactured by Hitachi High-Technologies Corporation, model UH-4150) was used.

[0282] It should be noted that the spectral characteristics in the case where the incident angle is not specifically specified are the values measured under the condition of an incident angle of 0 degrees (the direction perpendicular to the main surface of the filter).

[0283] The dyes used in each example are as follows.

[0284] Compound 1 (cyanine compound): Synthesized based on the method described in Dyes and Pigments, 73, 344-352 (2007).

[0285] Compound 2 (squaraine salt compound): Synthesized based on International Publication No. 2017 / 135359.

[0286] Compound 3 (mero-cyanine compound): Synthesized based on the specification of German Patent Gazette No. 10109243.

[0287] Compound 4 (squaraine salt compound): Synthesized based on Japanese Patent Laid-Open No. 2017-110209.

[0288] Compound 5 (squaraine Salt compound): Synthesized based on International Publication No. 2014 / 088063 and International Publication No. 2016 / 133099.

[0289]

[0290] The maximum absorption wavelengths of the polyimide resins of the respective pigments are shown in Table 2 described later.

[0291] <Spectral characteristics of glass>

[0292] As the glass used in the examples and comparative examples, Glass A1, Glass A2, Glass B, Glass C, Glass D1, and Glass D2 shown in Table 1 were prepared.

[0293] It should be noted that the above-mentioned Glass A1, Glass A2, Glass B, Glass D1, and Glass D2 are fluoro-phosphate glasses, and Glass C is a phosphate glass.

[0294] The spectral characteristics of the respective glasses are shown in Table 1 below.

[0295] [Table 1]

[0296]

[0297] As shown above, it can be seen that the fluoro-phosphate glass has a high transmittance in the visible light region and excellent shielding properties in the near-infrared light region, especially excellent shielding properties for light with wavelengths of 700 nm to 800 nm.

[0298] <Example 1: Filter>

[0299] A resin film was formed on one main surface of a fluoro-phosphate glass substrate A1 by the method shown below, thereby manufacturing a substrate having a glass substrate and a resin film. First, a polyimide resin (“C3G30G” (trade name) manufactured by Mitsubishi Gas Chemical Company, Inc., refractive index 1.59) was dissolved in γ-butyrolactone (GBL): cyclohexanone = 1:1 (mass ratio) to prepare a polyimide resin solution having a resin concentration of 8.5% by mass. Each of the above-mentioned pigments was added to the resin solution at the concentrations shown in Table 2 below with respect to 100 parts by mass of the resin, and stirred and dissolved at 50 °C for 2 hours to obtain a coating solution. The obtained coating solution was applied to the glass substrate by a spin coating method to form a resin film 1 with a film thickness of about 3 μm.

[0300] TiO2 and SiO2 were laminated on the other main surface of the glass substrate in the composition shown in Table 3 below by vapor deposition to form a dielectric multilayer film 1. In addition, TiO2 and SiO2 were laminated on the surface of the resin film in the composition shown in Table 4 below by vapor deposition to form a dielectric multilayer film 2.

[0301] By performing such operations, a filter having a structure of dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass A1 / resin film 1 / dielectric multilayer film 2 (Table 4) was fabricated.

[0302] <Examples 2 to 12: Filters>

[0303] Except for changing the glass, resin film, dielectric multilayer film 1, and dielectric multilayer film 2 to the structures shown below, the same operations as in Example 1 were performed to fabricate filters. The structures of the respective dielectric multilayer films are shown in Tables 3 to 6.

[0304] Example 2: Dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass A2 / resin film 1 / dielectric multilayer film 2 (Table 4)

[0305] Example 3: Dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass B / resin film 1 / dielectric multilayer film 2 (Table 4)

[0306] Example 4: Dielectric multilayer film 1 (Table 3) / phosphate glass C / resin film 1 / dielectric multilayer film 2 (Table 4)

[0307] Example 5: Dielectric multilayer film 1 (Table 5) / fluoro-phosphate glass A1 / resin film 1 / dielectric multilayer film 2 (Table 4)

[0308] Example 6: Dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass A1 / resin film 2 / dielectric multilayer film 2 (Table 4)

[0309] Example 7: Dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass D2 / resin film 1 / dielectric multilayer film 2 (Table 4)

[0310] Example 8: Dielectric multilayer film 1 (Table 3) / fluoro-phosphate glass D1 / resin film 3 / dielectric multilayer film 2 (Table 4)

[0311] Example 9: Dielectric multilayer film 1 (Table 6) / fluoro-phosphate glass D1 / resin film 3 / dielectric multilayer film 2 (Table 4)

[0312] Example 10: Dielectric multilayer film 1 (Table 6) / fluoro-phosphate glass D2 / resin film 3 / dielectric multilayer film 2 (Table 4)

[0313] Example 11: Dielectric multilayer film 1 (Table 6) / fluoro-phosphate glass D1 / resin film 4 / dielectric multilayer film 2 (Table 4)

[0314] Example 12: Dielectric multilayer film 1 (Table 6) / fluoro-phosphate glass D2 / resin film 4 / dielectric multilayer film 2 (Table 4)

[0315] For each resin film, the spectral transmittance curve was measured at an incident angle of 0 degrees in the wavelength range of 300 nm to 1200 nm using an ultraviolet-visible spectrophotometer. It should be noted that regarding the spectral characteristics of each resin film, for the resin film formed on a transparent glass substrate, in order to avoid the influence of reflections at the air interface and the glass interface, the internal transmittance was used for evaluation.

[0316] The results are shown in Table 2 below.

[0317] For each substrate (resin film and glass substrate), the spectral transmittance curve was measured at an incident angle of 0 degrees in the wavelength range of 300 nm to 1200 nm using an ultraviolet-visible spectrophotometer. It should be noted that regarding the spectral characteristics of each substrate, in order to avoid the influence of reflections at the air interface and the glass interface, the internal transmittance was used for evaluation.

[0318] The results are shown in Table 6 below.

[0319] For each filter, the spectral transmittance curves at incident angles of 0 degrees and 60 degrees and the spectral reflectance curve at an incident angle of 5 degrees were measured in the wavelength range of 300 nm to 1200 nm using an ultraviolet-visible spectrophotometer.

[0320] The results are shown in Tables 7 and 8 below.

[0321] In addition, the spectral transmittance curve of the filter of Example 1 is shown in Figure 2 , the spectral reflectance curve with the incident direction on the side of dielectric multilayer 1 is shown in Figure 3 , and the spectral reflectance curve with the incident direction on the side of dielectric multilayer 2 is shown in Figure 4 . The spectral transmittance curve of the filter of Example 2 is shown in Figure 5 , and the spectral reflectance curve with the incident direction on the side of dielectric multilayer 1 is shown in Figure 6 . The spectral transmittance curves of the filters of Examples 3 to 6 are shown in Figures 7 to 10 respectively.

[0322] It should be noted that Examples 1 to 2, 4, and 6 to 12 are examples, and Examples 3 and 5 are comparative examples.

[0323] [Table 2]

[0324]

[0325] [Table 3]

[0326]

[0327] [Table 4]

[0328]

[0329] [Table 5]

[0330]

[0331] [Table 6]

[0332]

[0333] [Table 7]

[0334]

[0335] [Table 8]

[0336]

[0337] Based on the above results, the average transmittance T of the optical filters of Example 1, Example 2, Example 4, and Example 6 to Example 12 440-600(0deg)AVE and the average transmittance T 440-600(60deg)AVE The absolute value of the difference is 15% or less. Even at a high incident angle of 60 degrees, the change in visible light transmittance is small. In addition, the average transmittance T 440-600(0deg)AVE is 75% or more, maintaining a high visible light transmittance. In addition, at an incident angle of 0 degrees, when the transmittance is 50%, the wavelength IR_T 50(0deg) is in the range of 580 nm to 640 nm, shielding the light in the near-infrared light region and effectively obtaining the visible light transmitted light. Furthermore, the average transmittance T 700-800(0deg)AVE is 1.1% or less and the average transmittance T 800-1200(0deg)AVE is 5% or less, and the shielding property of near-infrared light is excellent in a wide range.

[0338] On the other hand, the average transmittance T of the optical filter of Example 3 800-1200(0deg)AVE is greater than 5%, and the shielding property of near-infrared light is low. This is because the absorption of the glass substrate is insufficient.

[0339] The average transmittance T of the optical filter of Example 5 440-600(0deg)AVE and the average transmittance T 440-600(60deg)AVE The absolute value of the difference is greater than 15%, and the change in visible light transmittance is large at a high incident angle. This is because the reflectance of the near-infrared light region of the dielectric multilayer film 1 is too high.

[0340] The present invention has been described in detail with reference to specific embodiments, but various changes and modifications can be made without departing from the gist and scope of the present invention, which will be apparent to those skilled in the art. This application is based on a Japanese patent application (Japanese Patent Application No. 2022-210260) filed on December 27, 2022, the content of which is incorporated herein by reference.

[0341] Industrial Applicability

[0342] The filter of the present embodiment has excellent weather resistance, and has spectral characteristics such that even under conditions of a high incident angle, the change in spectral characteristics is small, the transmittance in the visible light region is excellent, and the shielding property in the near-infrared light region, particularly the shielding property in a wide range including 1200 nm, is excellent. It is useful in applications such as imaging devices such as cameras and sensors for conveyors, which have been advanced in performance in recent years.

[0343] Reference Numeral Explanation

[0344] 1B... Filter

[0345] 10... Near-infrared absorbing glass

[0346] 21, 22... Dielectric multilayer film

[0347] 30... Resin film

[0348] 40... Substrate

Claims

1. A filter, which successively includes a dielectric multilayer film 1, a substrate having a near-infrared absorbing glass and a resin film, and a dielectric multilayer film 2, wherein, the resin film contains a near-infrared absorbing pigment and a resin, the near-infrared absorbing glass is a fluoro-phosphate glass containing P, Cu, and F, the filter satisfies all of the following spectral characteristics (i-1) to (i-5): (i-1) The absolute value of the difference between the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 60 degrees 440-600(60deg)AVE is 15% or less; (i-2) The average transmittance T 440-600(0deg)AVE is 75% or more; (i-3) Wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) In the wavelength range of 580 nm to 640 nm; (i-4) The average transmittance T at a wavelength of 700 nm to 800 nm under the condition of an incident angle of 0 degrees 700-800(0deg)AVE is 1.1% or less; (i-5) The average transmittance T at a wavelength of 800 nm to 1200 nm under the condition that the incident angle is 0 degrees 800-1200(0deg)AVE is 5% or less.

2. The optical filter according to claim 1, wherein, the filter satisfies all of the following spectral characteristics (i-6) to (i-7): (i-6) When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 5 degrees 440-650(5deg)AVE is 1.5% or less; (i-7) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 850 nm to 1200 nm under the condition that the incident angle is 5 degrees 850-1200(5deg)AVE is 60% or more.

3. The optical filter according to claim 1, wherein, the filter satisfies the following spectral characteristic (i-8): When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 60 degrees 440-650(60deg)AVE is 10% or less.

4. The optical filter according to claim 1, wherein the filter satisfies all of the following spectral characteristics (i-9) to (i-10): (i-9) When the side of the medium multilayer film 2 is taken as the incident direction, the average reflectance R2 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 5 degrees 440-650(5deg)AVE is less than 2.0%; (i - 10) When the side of the medium multilayer film 2 is taken as the incident direction, the average reflectance R2 at a wavelength of 700 nm to 850 nm under the condition that the incident angle is 5 degrees 700-850(5deg)AVE is 1.2% or less.

5. The optical filter according to claim 1, wherein, the filter satisfies all of the following spectral characteristics (i-11) to (i-12): (i-11) When the side of the medium multilayer film 2 is taken as the incident direction, the average reflectance R2 at a wavelength of 440 nm to 650 nm under the condition that the incident angle is 60 degrees 440-650(60deg)AVE is less than 10%; When the side of the medium multilayer film 2 is the incident direction, the average reflectance R2 at a wavelength of 700 nm to 850 nm under the condition that the incident angle is 60 degrees 700-850(60deg)AVE is 8% or less.

6. The optical filter according to claim 1, wherein, the filter satisfies the following spectral characteristic (i-13): (i - 13) When the side of the medium multilayer film 1 is taken as the incident direction, the wavelength IR_R at which the reflectance is 50% under the condition of an incident angle of 5 degrees in the wavelength range of 750 nm to 900 nm 50(5deg) and the wavelength IR_T at which the transmittance is 50% under the condition of an incident angle of 5 degrees in the wavelength range of 580 nm to 640 nm 50(5deg) The absolute value of the difference is 160 nm or more.

7. The optical filter according to claim 1, wherein, the filter satisfies all of the following spectral characteristics (i-14) to (i-15): When the side of the dielectric multilayer film 1 is taken as the incident direction, the absorption loss amount in the wavelength range of X nm to Y nm is defined as follows X-Y : (Absorbed loss X-Y ) [%] = 100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees) (i-14) The average value of the absorption loss in the wavelength range of 700 nm to 800 nm 700-800 is 25% or more; (i-15) The average value of the absorption loss amount in the wavelength range of 850 nm to 1000 nm is 17% or more. 850-1000 ​ 8. The optical filter according to claim 1, wherein, the thickness of the near-infrared absorbing glass is 0.4 mm or less, the near-infrared absorbing glass satisfies all of the following spectral characteristics (ii-1) to (ii-3): (ii-1) Wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) In the wavelength range of 590 nm to 640 nm; (ii-2) Transmittance T of wavelength 700 nm under the condition that the incident angle is 0 degrees 700(0deg) is 25% or less; (ii-3) The average transmittance T of wavelengths from 700 nm to 800 nm under the condition that the incident angle is 0 degrees 700-800(0deg)AVE is 10% or less.

9. The optical filter according to claim 1, wherein, the substrate satisfies all of the following spectral characteristics (iii-1) to (iii-3): (iii-1) The average internal transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 0 degrees (in)440-600(0deg)AVE is 75% or more; (iii-2) The average internal transmittance T at a wavelength of 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE is 1.2% or less; (iii-3) The average internal transmittance T of wavelengths from 800 nm to 1000 nm under the condition that the incident angle is 0 degrees (in)800-1000(0deg)AVE is 5% or less.

10. The optical filter according to claim 1, wherein, The near-infrared absorbing pigment is a squarylium salt pigment contained in the resin and having a maximum absorption wavelength in the range of 740 nm to 800 nm. pigment.

11. The optical filter according to claim 1, wherein, the resin film satisfies all of the following spectral characteristics (iv-1) to (iv-4): (iv-1) The average internal transmittance T at a wavelength of 440 nm to 600 nm under the condition of an incident angle of 0 degrees (in)440-600(0deg)AVE is 90% or more; (iv-2) Wavelength IR_T at which the internal transmittance is 50% under the condition that the incident angle is 0 degrees (in)50(0deg) In the wavelength range of 630 nm to 645 nm; (iv-3) In the wavelength range of 500 nm to 700 nm, the wavelength IR_T when the internal transmittance is 70% under the condition of an incident angle of 0 degrees (in)70(0deg) and the wavelength IR_T when the transmittance is 20% under the condition of an incident angle of 0 degrees (in)20(0deg) the absolute value of the difference is 60 nm or less; (iv-4) The average internal transmittance T at a wavelength of 700 nm to 800 nm under the condition that the incident angle is 0 degrees (in)700-800(0deg)AVE is 5% or less.

12. The optical filter according to claim 1, wherein, the near-infrared absorbing glass is a fluoro-phosphate glass, and in terms of mass%, the fluoro-phosphate glass contains: P 5+ ：30%～70% Al 3+ ：0%～20% Li + : 0% to 20% Na + : 0% to 25% K + ：0%～25% Mg 2+ : 0% to 10% Ca 2+ : 0% to 20% Sr 2+ ：0%～30% Ba 2+ : 0% to 40% ΣR + : 0.1% to 30% (R + is selected from Li + , Na + and K + and one or more components thereof) ΣR 2+ : 10% to 45% (R 2+ is selected from Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ among more than one component), and Cu 2+ : 1% to 20%, and In addition to F - When the component elements other than F are taken as 100 mass %, the fluorophosphate glass contains 5 mass % to 70 mass % of F in terms of the proportion of the addition. - .

13. An imaging device, wherein, The imaging device includes the filter according to any one of claims 1 to 12.

Images