Optical filter

Abstract

The present invention relates to an optical filter which is sequentially provided with 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 containing a near-infrared absorbing dye, an ultraviolet absorbing dye, and a resin, and which satisfies all specific spectral characteristics (i-1) to (i-9).

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] As such a filter, for example, there can be mentioned: a reflective filter in which dielectric thin films (dielectric multilayer films) having different refractive indices are alternately laminated on one or both sides of a transparent substrate and light to be shielded is reflected by light interference; an absorption-type filter that uses glass or a pigment that absorbs light in a specific wavelength range to absorb light to be shielded; various types such as a filter obtained by combining a reflective type and an absorption type.

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

[0005] A filter including a glass that absorbs light in the near-infrared region and a reflective layer including a dielectric multilayer film is described in Patent Document 2.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: International Publication No. 2019 / 168090

[0009] Patent Document 2: International Publication No. 2019 / 151348 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] In the filter described in Patent Document 1, light in the near-infrared light region is widely shielded only by the absorption characteristics of the pigment, resulting in a decrease in the transmittance in the visible light region, and there is room for improvement in this regard.

[0012] In addition, in a filter that uses reflection of a dielectric multilayer film as in the filter described in Patent Document 2, since the optical film thickness of the dielectric multilayer film changes 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, a problem of reduced image reproducibility occurs. In particular, with the recent trend of lowering the height of camera modules, use under high incident angle conditions is envisaged, and thus a filter that is not easily affected by the incident angle is required.

[0013] In addition, since the reflected light is incident after being reflected again on the lens surface, or the light reflected on the sensor surface is incident after being reflected again on the surface of the dielectric multilayer film, there is sometimes a phenomenon of light generation outside the originally assumed optical path, so-called stray light. When such a filter is used, there is a possibility of generating glare or ghosting in the solid-state imaging device, or the image quality may deteriorate. In particular, with the recent improvement in the image quality of camera modules, a filter that is less likely to generate stray light is required.

[0014] In particular, from the viewpoint of suppressing the generation of blue glare or ghosting, a filter that suppresses the reflection characteristics in the ultraviolet light region on the light incident surface side so that the filter itself absorbs ultraviolet light is required.

[0015] An object of the present invention is to provide a filter having excellent transmittance in the visible light region, excellent shielding property in a wide range of near-infrared light region around 1200 nm, small change in spectral characteristics even under high incident angle conditions, suppression of stray light, and small reflection characteristics in the ultraviolet light region.

[0016] Means for Solving the Problems

[0017] The present invention provides a filter or the like having the following configuration.

[0018] [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

[0019] the resin film contains a near-infrared absorbing pigment, an ultraviolet absorbing pigment, and a resin,

[0020] the filter satisfies all of the following spectral characteristics (i-1) to (i-9):

[0021] (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 that the incident angle is 0 degree 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 is 12% or less;

[0022] (i-2) The average transmittance T 440-600(0deg)AVE is 78% or more;

[0023] (i-3) The wavelength IR_T at which the transmittance is 50% under the condition that the incident angle is 0 degree 50(0deg) is in the wavelength range of 590 nm to 640 nm;

[0024] (i-4) The average transmittance T at a wavelength of 700 nm to 800 nm under the condition that the incident angle is 0 degree700-800(0deg)AVE is 1% or less;

[0025] (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;

[0026] (i-6) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 370 nm to 420 nm under the condition that the incident angle is 5 degrees 370-420(5deg)AVE is 35% or less;

[0027] (i-7) When the medium multilayer film 1 side is the incident direction, the wavelength IR1_R when the reflectance is 50% under the condition that the incident angle is 5 degrees 50(5deg) is in the wavelength range of 790 nm to 860 nm;

[0028] (i-8) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 800 nm to 1000 nm under the condition that the incident angle is 5 degrees 800-1000(5deg)AVE is 75% or more;

[0029] (i-9) When the medium multilayer film 2 side is the incident direction, the average reflectance R2 at a wavelength of 400 nm to 800 nm under the condition that the incident angle is 5 degrees 400-800(5deg)AVE is 2% or less.

[0030] Advantages of the Invention

[0031] According to the present invention, it is possible to provide a filter having excellent transmittance in the visible light region, excellent shielding property in a wide range of near-infrared light region including around 1200 nm, small change in spectral characteristics even under high incident angle conditions, suppression of stray light, and small reflection characteristics in the ultraviolet light region. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a cross-sectional view schematically showing an example of a filter of one embodiment.

[0033] Figure 2 is a graph showing the spectral transmittance curves (0° transmittance, 60° transmittance) of the filter of Example 1.

[0034] Figure 3 is a graph showing the spectral reflectance curves (5° reflectance, 60° reflectance, medium multilayer film 1 side) of the filter of Example 1.

[0035] Figure 4 is a graph showing the spectral reflectance curves (5° reflectance, 60° reflectance, medium multilayer film 2 side) of the filter of Example 1.

[0036] Figure 5 A graph showing the spectral transmittance curves (0° transmittance, 60° transmittance) of the filter of Example 2.

[0037] Figure 6 A graph showing the spectral transmittance curves (0° transmittance, 60° transmittance) of the filter of Example 3.

[0038] Figure 7 A graph showing the spectral reflectance curves (5° reflectance, 60° reflectance, on the side of dielectric multilayer film 1) of the filter of Example 3.

[0039] Figure 8 A graph showing the spectral transmittance curves (0° transmittance, 60° transmittance) of the filter of Example 4.

[0040] Figure 9 A graph showing the spectral transmittance curves (0° transmittance, 60° transmittance) of the filter of Example 5. Detailed Embodiments

[0041] Hereinafter, embodiments of the present invention will be described.

[0042] In this specification, the near-infrared absorbing dye may sometimes be simply referred to as "NIR dye", and the ultraviolet absorbing dye may be simply referred to as "UV dye".

[0043] In this specification, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds represented by other formulas. The dye containing compound (I) is also referred to as dye (I), and the same applies to other dyes. In addition, the group represented by formula (I) is also denoted as group (I), and the same applies to groups represented by other formulas.

[0044] In this specification, the internal transmittance is the transmittance obtained by deducting the influence of interface reflection from the measured transmittance, which is represented by the formula {measured transmittance (incident angle 0 degrees) / (100 - reflectance (incident angle 5 degrees))} × 100.

[0045] 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.

[0046] The spectral characteristics can be measured using an ultraviolet-visible spectrophotometer.

[0047] In this specification, "~" indicating a numerical range includes the upper and lower limits.

[0048] <Filter>

[0049] 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, an ultraviolet absorbing pigment, and a resin.

[0050] 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, the near-infrared absorbing pigment, and the ultraviolet 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 changes in spectral characteristics even under high incident angle conditions can be obtained.

[0051] The configuration example of the filter of this embodiment will be described with reference to the drawings. Figure 1 It is a cross-sectional view schematically showing an example of a filter of one embodiment.

[0052] Figure 1 The shown filter 1B is an example including a dielectric multilayer film 21, a substrate 40 having a near-infrared absorbing glass 10 and a resin film 30, and a dielectric multilayer film 22.

[0053] The filter of this embodiment satisfies all of the following spectral characteristics (i-1) to (i-9).

[0054] (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 12% or less;

[0055] (i-2) The average transmittance T 440-600(0deg)AVE is 78% or more;

[0056] (i-3) The wavelength IR_T when the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) is in the wavelength range of 590 nm to 640 nm;

[0057] (i-4) The average transmittance T of 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% or less;

[0058] (i-5) The average transmittance T of 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;

[0059] (i-6) When the medium multilayer film 1 side is used as the incident direction, the average reflectance R1 of the wavelength range of 370 nm to 420 nm under the condition that the incident angle is 5 degrees 370-420(5deg)AVE is 65% or less;

[0060] (i-7) When the medium multilayer film 1 side is used as the incident direction, the wavelength IR1_R when the reflectance is 50% under the condition that the incident angle is 5 degrees 50(5deg) is in the wavelength range of 790 nm to 860 nm;

[0061] (i-8) When the medium multilayer film 1 side is used as the incident direction, the average reflectance R1 of the wavelength range of 800 nm to 1000 nm under the condition that the incident angle is 5 degrees 800-1000(5deg)AVE is 75% or more;

[0062] (i-9) When the medium multilayer film 2 side is used as the incident direction, the average reflectance R2 of the wavelength range of 400 nm to 800 nm under the condition that the incident angle is 5 degrees 400-800(5deg)AVE is 2% or less.

[0063] The filter of the present embodiment that satisfies all the spectral characteristics (i-1) to (i-9) has high visible light transmittance as shown in the characteristic (i-2), and has high near-infrared light shielding property in a wide range of 750 nm to 1200 nm as shown in the characteristics (i-4) and (i-5).

[0064] As shown in the spectral characteristic (i-6) that substantially reflects the reflection characteristics of the dielectric multilayer film, the reflection characteristics in the ultraviolet region are suppressed to be small, and at the same time, the light shielding property in the ultraviolet region is ensured by using an ultraviolet absorbing pigment. As shown in the spectral characteristic (i-8), the near-infrared region has a certain degree of reflection characteristics, but the light in the near-infrared region is also shielded by using a near-infrared absorbing pigment. As shown in the characteristic (i-1), even under the condition of a high incident angle, the change in the spectral characteristic is small. In addition, as shown in the spectral characteristic (i-9), the reflection characteristics on the other dielectric multilayer film side are suppressed to be small in a wide range, so stray light is not easily generated.

[0065] 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.

[0066] The absolute value of the difference in the spectral characteristic (i-1) is preferably 11% or less, more preferably 10% or less.

[0067] Average transmittance T 440-600(0deg)AVE It is preferably 79% or more, more preferably 79.5% or more.

[0068] The spectral characteristics (i-1) and (i-2) can be achieved, for example, by using a dielectric multilayer film with a low reflectance in the visible light region, using a near-infrared absorbing pigment and an ultraviolet absorbing pigment with a high transmittance in the visible light region, and using the glass described below as a near-infrared absorbing glass.

[0069] Satisfying the spectral characteristic (i-3) means that the color reproducibility of the captured image, especially in red, is excellent.

[0070] Wavelength IR_T 50(0deg) It is preferably in the range of 590 nm to 630 nm, more preferably in the range of 595 nm to 620 nm.

[0071] The spectral characteristic (i-3) can be achieved, for example, by using the glass described below as a near-infrared absorbing glass.

[0072] Satisfying the spectral characteristic (i-4) means that the near-infrared light shielding property is excellent.

[0073] Average transmittance T 700-800(0deg)AVE It is preferably 0.5% or less, more preferably 0.09% or less, and further preferably 0.08% or less.

[0074] The spectral characteristic (i-4) can be achieved, for example, by using two or more near-infrared absorbing pigments and using the glass described below as a near-infrared absorbing glass.

[0075] 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.

[0076] Average transmittance T 800-1200(0deg)AVE Is preferably 4.6% or less, more preferably 4.2% or less.

[0077] The spectral characteristic (i-5) can be achieved, for example, by using the glass described below as a near-infrared absorbing glass.

[0078] The spectral characteristics (i-6) to (i-9) substantially reflect the reflection characteristics of the dielectric multilayer film.

[0079] As shown in the spectral characteristics (i-6) to (i-8), the reflection characteristics of one dielectric multilayer film in the ultraviolet light region with a wavelength of 370 nm to 420 nm are small, and the reflection characteristics in the near-infrared light region with a wavelength of 800 nm to 1000 nm are large.

[0080] Average reflectance R1 370-420(5deg)AVE Is preferably 60% or less, more preferably 58% or less.

[0081] Wavelength IR1_R 50(5deg) Is preferably in the range of 790 nm to 850 nm, more preferably in the range of 795 nm to 840 nm.

[0082] Average reflectance R1 800-1000(5deg)AVE Is preferably 80% or more, more preferably 85% or more.

[0083] As shown in the spectral characteristic (i-9), the other dielectric multilayer film has small reflection characteristics in a wide range of visible light and near-infrared light with a wavelength of 400 nm to 800 nm and functions as an antireflection film. Thereby, a filter with high color reproducibility of a captured image can be provided.

[0084] Average reflectance R2 400-800(5deg)AVE Is preferably 1.5% or less, more preferably 1.0% or less.

[0085] The filter of the present embodiment preferably satisfies all of the following spectral characteristics (i-10) to (i-11).

[0086] (i-10) Wavelength UV_T when the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) Is in the wavelength range of 400 nm to 420 nm;

[0087] (i-11) Average transmittance T of wavelengths 370 nm to 400 nm under the condition that the incident angle is 0 degrees 370-400(0deg)AVE Is 10% or less.

[0088] Satisfying spectral characteristic (i-10) means that the color reproducibility of the captured image, especially in blue, is excellent.

[0089] Wavelength UV_T 50(0deg) More preferably, it is in the range of 405 nm to 420 nm, and even more preferably in the range of 410 nm to 420 nm.

[0090] Satisfying spectral characteristic (i-11) means that the shielding property in the ultraviolet light region is excellent.

[0091] Average transmittance T 370-400(0deg)AVE More preferably, it is 8% or less, and even more preferably 6% or less.

[0092] Spectral characteristics (i-10) and (i-11) can be achieved, for example, by using two or more ultraviolet absorbing pigments.

[0093] The filter of this embodiment preferably satisfies the following spectral characteristic (i-12).

[0094] (i-12) When the medium 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 range of wavelengths from 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 range of wavelengths from 500 nm to 700 nm 50(5deg) The absolute value of the difference is 145 nm or more.

[0095] Satisfying spectral characteristic (i-12) means that the light shielding region of the reflection characteristic is separated from the light shielding region of the absorption characteristic.

[0096] The absolute value of the difference in spectral characteristic (i-12) is more preferably 155 nm or more, and even more preferably 165 nm or more.

[0097] Spectral characteristic (i-12) can be achieved, for example, by using the medium multilayer film 21 described later.

[0098] The filter of this embodiment preferably satisfies the following spectral characteristic (i-13). In addition, it preferably satisfies the following spectral characteristic (i-14).

[0099] When the medium multilayer film 1 side is the incident direction, the absorption loss amount in the range of wavelengths from 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-13) The average value of the absorption loss in the wavelength range of 370 nm to 400 nm 370-400 is 9% or more.

[0102] (i-14) The average value of the absorption loss in the wavelength range of 700 nm to 800 nm 700-800 is 70% or more.

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

[0104] Satisfying the spectral characteristics (i-13) to (i-14) means that the light in the ultraviolet region and the near-infrared region is shielded by the absorption characteristics.

[0105] The average value of the absorption loss 370-400 is more preferably 30% or more, and still more preferably 50% or more.

[0106] The average value of the absorption loss 700-800 is more preferably 75% or more, still more preferably 80% or more, and particularly preferably 90% or more.

[0107] The spectral characteristics (i-13) to (i-14) can be achieved, for example, by using an ultraviolet absorbing pigment having a maximum absorption wavelength in the wavelength range of 350 nm to 420 nm and a near-infrared absorbing pigment having a maximum absorption wavelength in the wavelength range of 700 nm to 800 nm.

[0108] The filter of the present embodiment preferably satisfies all of the following spectral characteristics (i-15) to (i-17).

[0109] (i-15) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at an incident angle of 5 degrees in the wavelength range of 430 nm to 650 nm 430-650(5deg)AVE is 2% or less;

[0110] (i-16) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at an incident angle of 60 degrees in the wavelength range of 430 nm to 650 nm 430-650(60deg)AVE is 9% or less;

[0111] (i-17) When the medium multilayer film 1 side is the incident direction, the average reflectance R1 at an incident angle of 5 degrees in the wavelength range of 840 nm to 960 nm 840-960(5deg)AVE is 85% or more.

[0112] Satisfying the spectral characteristics (i-15) to (i-17) essentially means that the dielectric multilayer film 1 has small reflection characteristics in the visible light region even under the condition of a high incident angle, and has reflection characteristics in the near-infrared light region with wavelengths from 840 nm to 960 nm.

[0113] Average reflectance R1 430-650(5deg)AVE More preferably, it is 1.5% or less, and further preferably 1% or less.

[0114] Average reflectance R1 430-650(60deg)AVE More preferably, it is 8.5% or less, and further preferably 8% or less.

[0115] Average reflectance R1 840-960(5deg)AVE More preferably, it is 90% or more, and further preferably 95% or more.

[0116] By designing the dielectric multilayer film 1 in such a way as to have the above characteristics, the above spectral characteristics can be achieved.

[0117] The filter of this embodiment preferably satisfies the following spectral characteristic (i-18).

[0118] (i-18) When the dielectric multilayer film 1 side is the incident direction, at an incident angle of 5 degrees, the reflectance R1 at each wavelength is read at 1-nm intervals from a wavelength of 840 nm to a wavelength of 960 nm n(5deg) (n: any integer), the reflectance R1 n(5deg) is 93% or more for 75 or more n.

[0119] Satisfying the spectral characteristic (i-18) means that the light in the near-infrared light region with wavelengths from 840 nm to 960 nm is shielded by the reflection characteristic.

[0120] Reflectance R1 n(5deg) is more preferably 80 or more, further preferably 85 or more, and particularly preferably 90 or more for n that is 93% or more.

[0121] The spectral characteristic (i-18) can be achieved, for example, by using a dielectric multilayer film with high reflectance in the wavelength range of 800 nm to 1000 nm.

[0122] <Near-infrared absorbing glass>

[0123] The near-infrared absorbing glass in the filter of this embodiment preferably satisfies all of the following spectral characteristics (ii-1) to (ii-2). In addition, it preferably satisfies the following spectral characteristic (ii-3).

[0124] (ii-1) The average transmittance T at wavelengths from 400 nm to 600 nm under the condition of an incident angle of 0 degrees 400-600(0deg)AVE is 75% or more;

[0125] (ii-2) 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 25% or less;

[0126] (ii-3) The transmittance T at a wavelength of 1200 nm under the condition that the incident angle is 0 degrees 1200(0deg) is 25% or less.

[0127] As shown in the spectral characteristics (ii-1) to (ii-3), the visible light transmittance of the near-infrared absorbing glass is excellent, and the near-infrared light in a wide range of 800 nm to 1200 nm is absorbed. Thus, a filter can be obtained that can sufficiently shield this region even without enhancing the near-infrared light reflection characteristics of the dielectric multilayer film, and the spectral characteristics change little even under the condition of a high incident angle.

[0128] From the viewpoint of easily satisfying the above spectral characteristics, the near-infrared absorbing glass in the filter of the present embodiment is preferably a phosphate glass, a fluorophosphate glass, a silicophosphate glass, a thiophosphate glass, etc. containing near-infrared absorbing components such as iron and copper.

[0129] The thickness of the near-infrared absorbing glass in the filter of the present embodiment is preferably 0.5 mm or less, 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, more preferably 0.15 mm or more.

[0130] <Dielectric Multilayer Film>

[0131] The filter of the present 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 the 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.

[0132] The NIR reflection film preferably has, for example, wavelength selectivity that allows visible light to transmit, allows the near-infrared light in the transmission region of the absorption layer to transmit, and mainly reflects the near-infrared light other than the near-infrared light in the transmission region of the absorption layer.

[0133] As shown in the spectral characteristic (i-8) of the above filter, at least one of the dielectric multilayer films is preferably a reflection film having reflection characteristics in the near-infrared light region of 800 nm to 1000 nm, and this characteristic is used to shield light.

[0134] By combining the reflection characteristics in this specific wavelength range with the absorption characteristics of near-infrared absorbing pigments and near-infrared absorbing glass, it is possible to shield light in the near-infrared light region with wavelengths from 800 nm to 1200 nm over a wide range.

[0135] On the other hand, as shown in the spectral characteristics (i-9) of the above filter, it is preferable that the dielectric multilayer film as the reflection film has little change in the reflection 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.

[0136] As can be seen from the above, at least one dielectric multilayer film is preferably designed as a reflection layer that does not reflect visible light and reflects near-infrared light (wavelengths 800 nm to 1000 nm) under the conditions of an incident angle of light of 0 degrees and 60 degrees. In addition, it is preferable that the dielectric multilayer film 1 is a reflection layer.

[0137] As shown in the spectral characteristics (i-9) of the above filter, the other dielectric multilayer film is preferably designed as an antireflection layer with small reflection characteristics in both the visible light region and the near-infrared light region. In addition, it is preferable that the dielectric multilayer film 2 is an antireflection layer.

[0138] The dielectric multilayer film is constituted by, for example, a dielectric multilayer film obtained by laminating dielectric films with 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.

[0139] 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 formation properties, reproducibility of refractive index, stability, etc.

[0140] 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. Examples of materials for the medium refractive index film include: ZrO2, Nb2O5, Al2O3, HfO2; 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., Inc., etc. Among them, considering film formation properties, reproducibility of refractive index, stability, etc., Al2O3-based compounds and mixtures of Al2O3 and ZrO2 are preferred.

[0141] 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. Examples of materials for the low refractive index film include: SiO2, SiO x N y , MgF2, etc. Examples of other commercially available products include: S4F, S5F (a mixture of SiO2 and Al2O3) manufactured by Canon Optron Co., Ltd. Among them, considering film formation property reproducibility, stability, economy, etc., SiO2 is preferred.

[0142] For the dielectric multilayer film, [the sum T(H) of the QWOTs of the dielectric films with relatively higher refractive indices] / [the sum T(L) of the QWOTs of the dielectric films with relatively lower refractive indices] 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.

[0143] 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.

[0144] QWOT = physical film thickness / center wavelength (500 nm) × 4 × refractive index at a wavelength of 500 nm

[0145] 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 the QWOTs is the sum of the QWOTs of the high refractive index films, and the sum T(L) of the QWOTs is the sum of the QWOTs of the low refractive index films.

[0146] 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 the QWOTs is the sum of the QWOTs of the medium refractive index films, and the sum T(L) of the QWOTs is the sum of the QWOTs of the low refractive index films.

[0147] In the case where the dielectric multilayer film is a laminate of a medium refractive index film and a high refractive index film, the sum T(H) of the QWOTs is the sum of the QWOTs of the high refractive index films, and the sum T(L) of the QWOTs is the sum of the QWOTs of the medium refractive index films.

[0148] In addition, the dielectric multilayer film is preferably a multilayer film obtained by alternately laminating 10 or more layers each of an H2 layer and an M2 layer defined below.

[0149] 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.

[0150] M2 layer: A single layer or a multilayer existing between two H2 layers and having a sum of QWOTs of 1.2 or more and 1.8 or less.

[0151] The above-mentioned specific laminated structure is a structure obtained by alternately laminating 10 or more 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.

[0152] 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. However, 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.

[0153] The dielectric multilayer film having the above-mentioned specific laminated structure is preferably at least a dielectric multilayer film designed as a reflective layer.

[0154] In the case where the dielectric multilayer film designed as a reflective layer has the above-mentioned laminated structure, the layer closest to the near-infrared absorbing glass in the H2 layer and the M2 layer is preferably an 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.

[0155] As the dielectric multilayer film designed as a reflective layer, 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. Therefore, the total number of laminated layers is preferably 110 or less, more preferably 80 or less, and even more preferably 60 or less.

[0156] In addition, the film thickness (physical film thickness) of the dielectric multilayer film designed as a reflective layer is preferably 1 μm to 6 μm as a whole.

[0157] When the filter is installed in the 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, further preferably 20 layers or less, and in addition, it is preferably 6 layers or more.

[0158] 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.

[0159] 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.

[0160] When the filter is installed in the 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.

[0161] <Resin film>

[0162] The resin film in the filter of this embodiment contains resin, near-infrared absorbing pigment, and ultraviolet absorbing pigment. Here, the resin refers to the resin constituting the resin film.

[0163] As the near-infrared absorbing pigment, a pigment having a maximum absorption wavelength in the range of 700 nm to 800 nm in the resin is preferred. A pigment having a maximum absorption wavelength in the range of 700 nm to 800 nm, a steep absorption rise, and a small absorption loss in the visible light region is particularly preferred. Thereby, a filter with a small incident angle dependence while maintaining a high transmittance in the red wavelength band (600 nm to 700 nm) can be obtained.

[0164] 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 diimmonium pigments can be listed, 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 700 nm to 800 nm and easily exerting the effects of the present invention, squarylium salt pigments and cyanine pigments are preferred. In addition, it is preferred to use two or more near-infrared absorbing pigments. Thereby, it is easy to maintain high visible light transmittance.

[0165] The content of the near-infrared absorbing pigment in the resin film is preferably 0.1 to 30 parts by mass, more preferably 0.1 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.

[0166] As the ultraviolet absorbing pigment, a pigment having a maximum absorption wavelength in the range of 350 nm to 420 nm in the resin is preferred. Particularly preferred is a pigment having a maximum absorption wavelength in the range of 350 nm to 420 nm and a steep rise in absorption. Thereby, a filter having a small absorption loss in the visible light region while effectively blocking the ultraviolet light region can be obtained.

[0167] Examples of the ultraviolet absorbing pigment 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. In addition, it is preferred to use two or more ultraviolet absorbing pigments. Thereby, it is easy to maintain high visible light transmittance.

[0168] The content of the ultraviolet absorbing pigment in the resin film is preferably 0.5 to 20 parts by mass, more preferably 1 to 10 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.

[0169] 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 of them can be mixed and used.

[0170] 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.

[0171] In the case of using a plurality of pigments, these pigments can be contained in the same resin film, or can be separately contained in different resin films.

[0172] The resin film can be formed by preparing a coating solution by dissolving or dispersing a pigment, a resin or a raw material component of the resin, and each component compounded as needed in a solvent, applying the coating solution onto a support and drying it, and further curing it as needed. The support at this time can be the near-infrared absorbing glass for this filter, or 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.

[0173] In addition, in order to improve voids caused by minute bubbles, depressions caused by adhesion of foreign substances, etc., and shrinkage holes in the drying process, the coating solution can contain a surfactant. In addition, in the application of the coating solution, for example, a dipping method, a casting coating method, a spin coating method, etc. can be used. The above coating solution is applied onto a support and then dried, thereby forming a resin film. In addition, when the coating solution contains a raw material component of a transparent resin, a curing treatment such as thermal curing or photocuring is further performed.

[0174] In addition, the resin film can also be formed into a film shape by extrusion molding. The obtained film-shaped resin film is laminated on phosphate glass and integrated by thermal pressing or the like, thereby enabling the manufacture of a substrate.

[0175] The filter can have one resin film or two or more resin films. When there are two or more resin films, each layer can have the same configuration or a different configuration. In addition, when there are two or more resin films, they can all be laminated on the same main surface side of the near-infrared absorbing glass, or can be laminated on different main surface sides respectively.

[0176] From the viewpoints of the in-plane film thickness distribution and appearance quality in the coated substrate, the thickness of the resin film is 10 μm or less, preferably 5 μm or less. In addition, from the viewpoint of exhibiting desired spectral characteristics at 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, it is preferable that the total thickness of each resin film is within the above range.

[0177] The filter of this embodiment can, for example, include constituent elements (layers) that generate 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 can 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 a high visible light transmittance and have light absorption properties in a wide range of infrared wavelength regions greater than 1200 nm.

[0178] 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.

[0179] As described above, the following filters, etc. are disclosed in this specification.

[0180] [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,

[0181] the resin film contains a near-infrared absorbing pigment, an ultraviolet absorbing pigment, and a resin,

[0182] the filter satisfies all of the following spectral characteristics (i-1) to (i-9):

[0183] (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 that the incident angle is 0 degree 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 is 12% or less;

[0184] (i-2) The average transmittance T 440-600(0deg)AVE is 78% or more;

[0185] (i-3) The wavelength IR_T when the transmittance is 50% under the condition that the incident angle is 0 degree 50(0deg) is in the wavelength range of 590 nm to 640 nm;

[0186] (i-4) The average transmittance T at a wavelength of 700 nm to 800 nm under the condition that the incident angle is 0 degree 700-800(0deg)AVE is 1% or less;

[0187] (i-5) The average transmittance T at a wavelength of 800 nm to 1200 nm under the condition that the incident angle is 0 degree 800-1200(0deg)AVE is 5% or less;

[0188] (i-6) When the dielectric multilayer film 1 side is the incident direction, the average reflectance R1 at a wavelength of 370 nm to 420 nm under the condition that the incident angle is 5 degrees 370-420(5deg)AVE is 65% or less;

[0189] (i - 7) When the side of the dielectric multilayer film 1 is taken as the incident direction, the wavelength IR1_R at which the reflectance is 50% under the condition that the incident angle is 5 degrees 50(5deg) In the wavelength range of 790 nm to 860 nm;

[0190] (i - 8) When the side of the dielectric multilayer film 1 is taken as the incident direction, the average reflectance R1 in the wavelength range of 800 nm to 1000 nm under the condition that the incident angle is 5 degrees 800-1000(5deg)AVE is 75% or more;

[0191] (i - 9) When the side of the dielectric multilayer film 2 is taken as the incident direction, the average reflectance R2 in the wavelength range of 400 nm to 800 nm under the condition that the incident angle is 5 degrees 400-800(5deg)AVE is 2% or less.

[0192] [2] The filter according to [1], wherein the filter satisfies all of the following spectral characteristics (i - 10) to (i - 11):

[0193] (i - 10) The wavelength UV_T at which the transmittance is 50% under the condition that the incident angle is 0 degree 50(0deg) is in the range of 400 nm to 420 nm;

[0194] (i - 11) The average transmittance T in the wavelength range of 370 nm to 400 nm under the condition that the incident angle is 0 degree 370-400(0deg)AVE is 10% or less.

[0195] [3] The filter according to [1] or [2], wherein the filter satisfies the following spectral characteristic (i - 12):

[0196] (i - 12) When the side of the dielectric multilayer film 1 is taken as the incident direction, the wavelength IR_R at which the reflectance is 50% in the wavelength range of 750 nm to 900 nm under the condition that the incident angle is 5 degrees 50(5deg) and the wavelength IR_T at which the transmittance is 50% in the wavelength range of 500 nm to 700 nm under the condition that the incident angle is 5 degrees 50(5deg) The absolute value of the difference is 145 nm or more.

[0197] [4] The filter according to any one of [1] to [3], wherein the filter satisfies the following spectral characteristic (i - 13):

[0198] 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 :

[0199] (Absorption loss amount X-Y)[%]=100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees)

[0200] (i - 13) Absorption loss amount in the wavelength range of 370 nm to 400 nm 370-400 The average value is 9% or more.

[0201] [5] The filter according to any one of [1] to [4], wherein the filter satisfies the following spectral characteristic (i - 14):

[0202] 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 :

[0203] (Absorption loss amount X-Y )[%]=100 - (Transmittance at an incident angle of 5 degrees) - (Reflectance at an incident angle of 5 degrees)

[0204] (i - 14) Absorption loss amount in the wavelength range of 700 nm to 800 nm 700-800 The average value is 70% or more.

[0205] [6] The filter according to any one of [1] to [5], wherein the filter satisfies all of the following spectral characteristics (i - 15) to (i - 17):

[0206] (i - 15) Average reflectance R1 at wavelengths of 430 nm to 650 nm at an incident angle of 5 degrees when the medium multilayer film 1 side is the incident direction 430-650(5deg)AVE is 2% or less;

[0207] (i - 16) Average reflectance R1 at wavelengths of 430 nm to 650 nm at an incident angle of 60 degrees when the medium multilayer film 1 side is the incident direction 430-650(60deg)AVE is 9% or less;

[0208] (i - 17) Average reflectance R1 at wavelengths of 840 nm to 960 nm at an incident angle of 5 degrees when the medium multilayer film 1 side is the incident direction 840-960(5deg)AVE is 85% or more.

[0209] [7] The filter according to any one of [1] to [6], wherein the filter satisfies the following spectral characteristic (i - 18):

[0210] (i - 18) When the medium multilayer film 1 side is taken as the incident direction, under the condition that the incident angle is 5 degrees, the reflectance R1 at each wavelength is read at intervals of 1 nm from a wavelength of 840 nm to a wavelength of 960 nm. n(5deg) (n: any integer), the reflectance R1 n(5deg) There are 75 or more n with a reflectance R1 of 93% or more.

[0211] [8] The filter according to any one of [1] to [7], wherein the near-infrared absorbing glass satisfies all of the following spectral characteristics (ii - 1) to (ii - 2):

[0212] (ii - 1) The average transmittance T in the wavelength range of 400 nm to 600 nm under the condition that the incident angle is 0 degrees 400-600(0deg)AVE is 75% or more;

[0213] (ii - 2) 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 25% or less.

[0214] [9] The filter according to any one of [1] to [8], wherein the near-infrared absorbing glass satisfies the following spectral characteristic (ii - 3):

[0215] (ii - 3) The transmittance T at a wavelength of 1200 nm under the condition that the incident angle is 0 degrees 1200(0deg) is 25% or less.

[0216]

[10] The filter according to any one of [1] to [9], wherein the resin film contains two or more ultraviolet absorbing pigments having a maximum absorption wavelength in the range of 350 nm to 420 nm in the resin.

[0217]

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

[10] , wherein the resin film contains two or more near-infrared absorbing pigments having a maximum absorption wavelength in the range of 700 nm to 800 nm in the resin.

[0218]

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

[11] .

[0219] Examples

[0220] Next, the present invention will be described more specifically by way of examples.

[0221] A UV-visible spectrophotometer (manufactured by Hitachi High-Technologies Corporation, model UH - 4150) was used in the measurement of each spectral characteristic.

[0222] Note that the spectral characteristics under the condition where the incident angle is not specifically and clearly 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).

[0223] The pigments used in each example are as described below.

[0224] Compound 1 (cyanine compound): Synthesized based on the method described in Dyes and Pigments, 73, 344 - 352 (2007).

[0225] Compound 2 (squaraine salt compound): Synthesized based on International Publication No. 2017 / 135359.

[0226] Compound 3 (mero - cyanine compound): Synthesized based on the specification of German Patent Gazette No. 10109243.

[0227] Compound 4 (squaraine salt compound): Synthesized based on Japanese Patent Application Laid - Open No. 2017 - 110209.

[0228]

[0229] The maximum absorption wavelengths of the respective pigments in the polyimide resin are shown in Table 2 described later.

[0230] <Spectral Characteristics of Glass>

[0231] The following glasses were prepared as the glasses used in the examples and comparative examples.

[0232] Glass 1, Glass 2: Fluorophosphate glass (manufactured by AGC Techno Glass Co., Ltd., NF - 50GX)

[0233] Glass 3: Soda glass (manufactured by Schott AG, D263)

[0234] Glass 4: Fluorophosphate glass (containing, by mass%, P 5+ : 34.9%, Al 3+ : 7.9%, Na + : 7.3%, K + : 13.7%, Ca 2+ : 4.8%, Sr 2+ : 7.2%, Ba 2+ : 15.5%, Cu 2+ : 8.7%, when the component elements other than F - contained in the glass are set to 100% by mass, contains 14.2% by mass of F - )

[0235] It should be noted that among the above-mentioned glasses, the near-infrared absorbing glasses are Glass 1, Glass 2, and Glass 4.

[0236] The spectral characteristics of each glass are shown in Table 1 below.

[0237] In addition, the spectral characteristics of each near-infrared absorbing glass are shown in Table 1.

[0238] [Table 1]

[0239]

[0240] As shown above, it can be seen that Glass 1 has a high transmittance in the visible light region and excellent light-shielding properties in the near-infrared light region.

[0241] <Example 1: Filter>

[0242] A resin film was formed on one main surface of the glass substrate of Glass 1 by the method shown below, thereby manufacturing a base material having a glass substrate and a resin film. First, 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 mass%. Each of the above pigments was added to the resin solution at the concentrations shown in Table 2 below relative 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 spin coating to form a resin film 1 with a film thickness of about 3 μm.

[0243] 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.

[0244] By operating in this way, a filter having a structure of dielectric multilayer film 1 (Table 3) / Glass 1 / resin film 1 / dielectric multilayer film 2 (Table 4) was manufactured.

[0245] <Examples 2 to 6: Filter>

[0246] Except that the glass, resin film, dielectric multilayer film 1, and dielectric multilayer film 2 were changed to the compositions shown below, the same operations as in Example 1 were performed to manufacture a filter. The compositions of the respective dielectric multilayer films are shown in Tables 3 to 8.

[0247] Example 2: dielectric multilayer film 1 (Table 3) / Glass 2 / resin film 1 / dielectric multilayer film 2 (Table 6)

[0248] Example 3: Dielectric multilayer film 1 (Table 4) / Glass 2 / Resin film 1 / Dielectric multilayer film 2 (Table 6)

[0249] Example 4: Dielectric multilayer film 1 (Table 3) / Glass 3 / Resin film 1 / Dielectric multilayer film 2 (Table 6)

[0250] Example 5: Dielectric multilayer film 1 (Table 5) / Glass 2 / Resin film 1 / Dielectric multilayer film 2 (Table 7)

[0251] Example 6: Dielectric multilayer film 1 (Table 8) / Glass 4 / Resin film 2 / Dielectric multilayer film 2 (Table 6)

[0252] For each of the filters, 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 in the wavelength range of 300 nm to 1200 nm were measured using an ultraviolet-visible spectrophotometer.

[0253] The results are shown in Table 9 below.

[0254] In addition, the spectral transmittance curve of the filter of Example 1 is shown in Figure 2 and the spectral reflectance curve on the dielectric multilayer film 1 side is shown in Figure 3 and the spectral reflectance curve on the dielectric multilayer film 2 side is shown in Figure 4 The spectral transmittance curve of the filter of Example 2 is shown in Figure 5 The spectral transmittance curve of the filter of Example 3 is shown in Figure 6 and the spectral reflectance curve on the dielectric multilayer film 1 side is shown in Figure 7 The spectral transmittance curve of the filter of Example 4 is shown in Figure 8 The spectral transmittance curve of the filter of Example 5 is shown in Figure 9 .

[0255] It should be noted that Examples 1 to 2 and Example 6 are examples, and Examples 3 to 5 are comparative examples.

[0256] [Table 2]

[0257]

[0258] [Table 3]

[0259]

[0260] [Table 4]

[0261]

[0262] [Table 5]

[0263]

[0264] [Table 6]

[0265]

[0266] [Table 7]

[0267]

[0268] [Table 8]

[0269]

[0270] [Table 9]

[0271]

[0272] Based on the above results, the average transmittance T of the filters in Examples 1 to 2 and Example 6 440-600(0deg)AVE and the average transmittance T 440-600(60deg)AVE have an absolute difference of 12% 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 78% or more, maintaining a high visible light transmittance. In addition, 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 590 nm to 640 nm. Furthermore, the average transmittance T 700-800(0deg)AVE is 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. In addition, in the filters of Examples 1 to 2 and Example 6, according to the reflectance results, one dielectric multilayer film has a low UV reflectance and a high reflectance in the near-infrared light region of 800 nm to 1000 nm, and the other dielectric multilayer film has a low reflectance in the visible light region and the near-infrared light region of 400 nm to 800 nm.

[0273] On the other hand, the absolute difference between the average transmittance T of the filter of Example 3 440-600(0deg)AVE and the average transmittance T 440-600(60deg)AVE is greater than 10%, and the change in visible light transmittance is large under the condition of a high incident angle. This is because the spectral characteristics of dielectric multilayer film 1 change greatly according to the incident angle.

[0274] The wavelength IR_T of the filter of Example 4 50(0deg) is out of the wavelength range of 590 nm to 640 nm, the average transmittance T 700-800(0deg)AVE is greater than 1%, the average transmittance T 800-1200(0deg)AVE is greater than 5%, and the shielding property of near-infrared light is low. This is because the glass substrate does not have the property of absorbing near-infrared light.

[0275] The average reflectance R on the side of dielectric multilayer film 1 of the filter of Example 5370-420(5deg)AVE Greater than 35%, with a high ultraviolet light reflectivity. This is because the ultraviolet light reflectivity of the dielectric multilayer film 1 is high.

[0276] The present invention has been described in detail with reference to specific embodiments, but it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the gist and scope of the present invention. This application is based on a Japanese patent application (Japanese Patent Application No. 2022-210261) filed on December 27, 2022, the content of which is incorporated herein by reference.

[0277] Industrial Applicability

[0278] The filter of this embodiment has spectral characteristics with little change in spectral characteristics even under conditions of a high incident angle, excellent transmittance in the visible light region, and excellent shielding properties in the near-infrared light region, particularly excellent shielding properties in a wide range including 1200 nm. It is useful in applications such as imaging devices such as cameras and sensors for conveyors that have been promoted to high performance in recent years.

[0279] Reference Numeral Explanation

[0280] 1B... Filter

[0281] 10... Near-infrared absorbing glass

[0282] 21, 22... Dielectric multilayer film

[0283] [[ID=**************]]

[0284] 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, an ultraviolet absorbing pigment, and a resin, the filter satisfies all of the following spectral characteristics (i-1) to (i-9): (i-1) The average transmittance T of wavelengths from 440 nm to 600 nm under the condition of an incident angle of 0 degrees 440-600(0deg)AVE and the average transmittance T of wavelengths from 440 nm to 600 nm under the condition of an incident angle of 60 degrees 440-600(60deg)AVE The absolute value of the difference is 12% or less; (i-2) The average transmittance T 440-600(0deg)AVE is 78% 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 590 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% 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; When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 370 nm to 420 nm under the condition that the incident angle is 5 degrees 370-420(5deg)AVE is 65% or less; When the side of the medium multilayer film 1 is taken as the incident direction, the wavelength IR1_R at which the reflectance is 50% under the condition that the incident angle is 5 degrees 50(5deg) within the wavelength range of 790 nm to 860 nm; When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 800 nm to 1000 nm under the condition that the incident angle is 5 degrees 800-1000(5deg)AVE is 75% or more; (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 400 nm to 800 nm under the condition that the incident angle is 5 degrees 400-800(5deg)AVE is 2% or less.

2. The optical filter according to claim 1, wherein, the filter satisfies all of the following spectral characteristics (i-10) to (i-11): (i-10) The wavelength UV_T at which the transmittance is 50% under the condition that the incident angle is 0 degrees 50(0deg) within the range of wavelengths from 400 nm to 420 nm; (i-11) The average transmittance T at a wavelength of 370 nm to 400 nm under the condition that the incident angle is 0 degrees 370-400(0deg)AVE is 10% or less.

3. The optical filter according to claim 1, wherein the filter satisfies the following spectral characteristic (i-12): 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 500 nm to 700 nm 50(5deg) The absolute value of the difference is 145 nm or more.

4. The optical filter according to claim 1, wherein the filter satisfies the following spectral characteristic (i-13): When taking the side of the medium multilayer film 1 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-13) The average value of the absorption loss in the wavelength range of 370 nm to 400 nm 370-400 is 9% or more.

5. The optical filter according to claim 1, wherein, the filter satisfies the following spectral characteristic (i-14): When taking the side of the medium multilayer film 1 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 amount in the wavelength range of 700 nm to 800 nm 700-800 is 70% or more.

6. The optical filter according to claim 1, wherein the filter satisfies all of the following spectral characteristics (i-15) to (i-17): (i - 15) When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 430 nm to 650 nm under the condition that the incident angle is 5 degrees 430-650(5deg)AVE is 2% or less; (i-16) When the medium multilayer film 1 side is taken as the incident direction, the average reflectance R1 at a wavelength of 430 nm to 650 nm under the condition that the incident angle is 60 degrees 430-650(60deg)AVE is 9% or less; (i - 17) When the side of the medium multilayer film 1 is taken as the incident direction, the average reflectance R1 at a wavelength of 840 nm to 960 nm under the condition that the incident angle is 5 degrees 840-960(5deg)AVE is 85% or more.

7. The optical filter according to claim 1, wherein the filter satisfies the following spectral characteristic (i-18): When the side of the medium multilayer film 1 is taken as the incident direction, under the condition that the incident angle is 5 degrees, the reflectance R1 of each wavelength is read at intervals of 1 nm from a wavelength of 840 nm to a wavelength of 960 nm n(5deg) (n: any integer), the reflectance R1 n(5deg) There are 75 or more values of n for which it is 93% or more.

8. The optical filter according to claim 1, wherein, the near-infrared absorbing glass satisfies all of the following spectral characteristics (ii-1) to (ii-2): (ii-1) The average transmittance T at a wavelength of 400 nm to 600 nm under the condition that the incident angle is 0 degrees 400-600(0deg)AVE is 75% or more; (ii-2) 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 25% or less.

9. The optical filter according to claim 1, wherein, the near-infrared absorbing glass satisfies the following spectral characteristic (ii-3): (ii-3) Transmittance T at a wavelength of 1200 nm under the condition that the incident angle is 0 degrees 1200(0deg) is 25% or less.

10. The optical filter according to claim 1, wherein, the resin film contains two or more ultraviolet absorbing pigments having a maximum absorption wavelength in the range of 350 nm to 420 nm in the resin.

11. The optical filter according to claim 1, wherein, the resin film contains two or more near-infrared absorbing pigments having a maximum absorption wavelength in the range of 700 nm to 800 nm in the resin.

12. An imaging device, wherein, The imaging device includes the filter according to any one of claims 1 to 11.

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