Optical filter and imaging device

Abstract

An optical filter according to one embodiment of the present invention is provided with: a glass substrate which has a first main surface and a second main surface that are opposite to each other, and which contains a phosphoric acid glass; a first antireflection layer that is disposed on the first main surface side of the glass substrate; and a resin layer containing a dye, at least one layer of the resin layer being disposed on the second main surface side of the glass substrate, the composition of the glass substrate satisfying a predetermined range, the dye having a maximum absorption wavelength in the resin layer in a wavelength range of 690-800 nm, the thickness of the resin layer being 10 [mu] m or less, and the thickness of the resin layer being 10 [mu] m or less. The optical filter has all spectral characteristics of (a-1) to (a-6), and has a haze value of 2% or less.

Description

Technical Field

[0001] The invention relates to an optical filter and an imaging device. Background Art

[0002] Imaging devices such as car cameras and smartphone cameras are equipped with solid-state imaging elements (CCD, CMOS, etc.). However, solid-state imaging elements are more sensitive to infrared light than human visual sensitivity. Therefore, in order to make the image obtained by the solid-state imaging element close to human visual sensitivity, a filter is further provided in the imaging device.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2014 / 030628 Summary of the invention

[0006] Problems to be solved by the invention

[0007] High-precision optical filters are required to have (1) high transmittance in the visible light region, (2) high light shielding properties in the infrared region, and (3) no change in optical characteristics depending on the incident angle of light.

[0008] In order to satisfy such characteristics, Patent Document 1 describes an optical filter having a fluorophosphate glass substrate containing CuO. The fluorophosphate glass substrate containing CuO has a function of absorbing infrared rays to a certain extent. Therefore, by combining the fluorophosphate glass substrate containing CuO, the pigment-containing layer and the dielectric multilayer film, an optical filter having the effects of (1) to (3) described above can be provided.

[0009] However, according to the inventors of the present application, even for the optical filter described in Patent Document 1, the effects of (2) and (3) described above are not sufficient. In particular, optical filters for cameras mounted on electronic devices such as smartphones have been increasingly required to be lower in height in recent years. As such optical filters are being lowered, the problem of angular dependence of optical characteristics is expected to become more prominent in the future.

[0010] The present invention has been made in view of the above background. An object of the present invention is to provide an optical filter having a significantly high light shielding property in the infrared region and having significantly suppressed angular dependence of optical characteristics.

[0011] Means used to solve problems

[0012] In one embodiment of the present invention, there is provided an optical filter, wherein the optical filter comprises: a glass substrate having a first main surface and a second main surface opposite to each other and containing phosphate glass; a first anti-reflection layer, the first anti-reflection layer being arranged on the first main surface side of the glass substrate; and a resin layer, the resin layer containing a pigment, and at least one layer being arranged on the second main surface side of the glass substrate,

[0013] Calculated by mass percentage based on oxides, the glass substrate comprises:

[0014] 50% to 80% P2O5;

[0015] 5% to 20% Al2O3;

[0016] 4% to 20% CuO;

[0017] 0.5% to 15% of R(1)2O, wherein R(1) is at least one element selected from the group consisting of Li, Na, K, Rb and Cs; and

[0018] 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn,

[0019] The pigment has a maximum absorption wavelength in the resin layer within a wavelength range of 690 nm to 800 nm.

[0020] The thickness of the resin layer is less than 10 μm,

[0021] The filter has the following spectral characteristics:

[0022] (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%,

[0023] (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%.

[0024] (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%,

[0025] (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm.

[0026] (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at both incident angles θ = 0° and 50° （t）ave2 All are below 4.0%.

[0027] (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%.

[0028] The haze value of the filter is less than 2%.

[0029] Effects of the Invention

[0030] According to one embodiment of the present invention, it is possible to provide an optical filter having significantly high light shielding properties in the infrared region and significantly suppressing the angular dependence of optical characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The graphs compare and show typical optical properties of CuO-containing fluorophosphate glass (a) and phosphate glass (b).

[0032] Figure 2 This is a cross-sectional view schematically showing a configuration example of an optical filter according to one embodiment of the present invention.

[0033] Figure 3 This is a cross-sectional view schematically showing a configuration example of an optical filter according to another embodiment of the present invention.

[0034] Figure 4 This is a diagram schematically showing an example of optical characteristics of a glass substrate included in an optical filter according to one embodiment of the present invention.

[0035] Figure 5 This is a diagram schematically showing an example of optical characteristics of a resin layer that may be included in the optical filter according to one embodiment of the present invention.

[0036] Figure 6 This is a diagram schematically showing an example of the optical characteristics of the optical filter according to one embodiment of the present invention.

[0037] Figure 7 This is a diagram showing an example of a transmittance graph obtained by an optical filter according to an embodiment of the present invention.

[0038] Figure 8 This is a diagram showing an example of a reflectance graph obtained by an optical filter according to an embodiment of the present invention.

[0039] Fig. 9This is a diagram showing an example of a transmittance graph obtained by an optical filter according to another embodiment of the present invention. DETAILED DESCRIPTION

[0040] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0041] As mentioned above, it is difficult to say that the effects of (2) and (3) above are still sufficient for conventional optical filters. Therefore, conventional optical filters may not be able to sufficiently suppress light leakage in the infrared region and / or the phenomenon that optical characteristics vary depending on the incident angle of light (hereinafter referred to as the "angle dependency problem"). In particular, as the height of optical filters is further reduced in the future, the "angle dependency problem" is expected to become more significant.

[0042] Under such circumstances, the inventors of the present application have conducted intensive research and development on the structure of an optical filter that can further enhance the effects of (2) and (3). The inventors of the present application have found that when phosphate glass is used instead of fluorophosphate glass as the glass substrate containing an absorbent, absorption in the infrared region can be further enhanced, and that the "angle dependency problem" can be eliminated by not using an infrared cutoff film.

[0043] On the other hand, when the pigment-containing layer is thickened in order to enhance the effect of (2), the haze value of the filter increases, the light reflectance increases, and thus a tendency is observed to reduce the clarity of the image. The inventors of the present application have also studied the problem of such haze value. As a result, it was found that by adjusting the haze value of the filter to a specific range, the light shielding property in the infrared region can be significantly improved while maintaining the clarity of the image.

[0044] Therefore, in one embodiment of the present invention, there is provided an optical filter, wherein the optical filter comprises: a glass substrate having a first main surface and a second main surface opposite to each other and containing phosphate glass; a first anti-reflection layer, the first anti-reflection layer being arranged on the first main surface side of the glass substrate; and a resin layer, the resin layer containing a pigment, and at least one layer being arranged on the second main surface side of the glass substrate,

[0045] Calculated by mass percentage based on oxides, the glass substrate comprises:

[0046] 50% to 80% P2O5;

[0047] 5% to 20% Al2O3;

[0048] 4% to 20% CuO;

[0049] 0.5% to 15% of R(1)2O; wherein R(1) is at least one component selected from the group consisting of Li, Na, K, Rb and Cs; and

[0050] 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn,

[0051] The pigment has a maximum absorption wavelength in the resin layer within a wavelength range of 690 nm to 800 nm.

[0052] The thickness of the resin layer is less than 10 μm,

[0053] The filter has the following spectral characteristics:

[0054] (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%,

[0055] (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%.

[0056] (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%,

[0057] (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm.

[0058] (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at both incident angles θ = 0° and 50° （t）ave2 All are below 4.0%.

[0059] (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%.

[0060] The haze value of the filter is less than 2%.

[0061] In this specification, the haze value refers to a value measured in accordance with JIS K7136.

[0062] In the optical filter of one embodiment of the present invention, an infrared cutoff film is not used. Therefore, in the optical filter of one embodiment of the present invention, the "angle dependence problem" is not easy to occur. For example, even if the incident angle of light changes from 0° to 50°, the optical characteristics do not change much.

[0063] In one embodiment of the present invention, phosphoric acid glass is used as the glass for the glass substrate containing the absorbent. Figure 1 The representative optical properties of fluorophosphate glass and phosphate glass containing an absorber (CuO) are shown in FIG. Figure 1 In the figure, the horizontal axis is the wavelength of light and the vertical axis is the internal transmittance. Figure 1 In the graph, (a) is the internal transmittance of fluorophosphate glass containing an absorber, and (b) is the internal transmittance of phosphate glass containing an absorber.

[0064] It should be noted that, in the present application, “internal transmittance (%)” refers to the transmittance (%) when the incident angle is 5° as T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） The internal transmittance at is expressed by the following formula (3).

[0065] Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3)

[0066] like Figure 1 As shown in FIG. 1 , phosphoric acid glass containing an absorber has an internal transmittance equivalent to that of fluorophosphate glass containing an absorber in the wavelength range of 450 nm to 600 nm. Therefore, even if phosphoric acid glass is used instead of fluorophosphate glass as the glass substrate of the optical filter, a high internal transmittance can be maintained in the visible light region.

[0067] In addition, if Figure 1 As shown in FIG. 1 , phosphoric acid glass containing an absorber shows sufficiently lower internal transmittance than fluorophosphate glass containing an absorber in a wavelength range greater than 750 nm. Therefore, when phosphoric acid glass containing an absorber is used as a glass substrate of an optical filter, even if an infrared cutoff film is not used, the combination of an antireflection layer and a resin layer containing a pigment can significantly improve light shielding properties in the infrared region.

[0068] In addition, in one embodiment of the present invention, the glass substrate comprises, in terms of mass percentage based on oxides:

[0069] 50% to 80% P2O5;

[0070] 5% to 20% Al2O3;

[0071] 4% to 20% CuO;

[0072] 0.5% to 15% of R(1)2O, wherein R(1) is at least one element selected from the group consisting of Li, Na, K, Rb and Cs; and

[0073] 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn.

[0074] When the glass substrate has the above composition, the light shielding property in the infrared region can be significantly improved, and the transmittance in the visible light region can also be significantly improved at the same time.

[0075] In one embodiment of the present invention, the optical filter comprises: a first anti-reflection layer, the first anti-reflection layer is arranged on the first main surface side of the glass substrate; and a resin layer, the resin layer contains a pigment, and at least one layer is arranged on the second main surface side of the glass substrate. In addition, the pigment has a maximum absorption wavelength in the range of 690nm to 800nm ​​in the resin layer, and the thickness of the resin layer is 10μm or less.

[0076] When the thickness of the resin layer containing the pigment having the maximum absorption wavelength in the infrared region is 10 μm or less, the haze value of the filter can be reduced, and the light shielding property in the infrared region can be significantly improved while maintaining the clarity of the image.

[0077] Specifically, the haze value of the optical filter is 2% or less. When the haze value of the optical filter is 2% or less, the light shielding property in the infrared region can be significantly improved while maintaining the clarity of the image.

[0078] Furthermore, in one embodiment of the present invention, the filter has the following spectral characteristics:

[0079] (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%,

[0080] (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%.

[0081] (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%,

[0082] (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm.

[0083] (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at both incident angles θ = 0° and 50° （t）ave2 All are below 4.0%.

[0084] (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%.

[0085] When the optical filter has the spectral characteristics (a-1) to (a-6) described above, the light shielding property in the infrared region can be significantly improved, and the angular dependency of the optical characteristics can be significantly suppressed.

[0086] Due to the above effects, in one embodiment of the present invention, it is possible to provide an optical filter having significantly high light shielding properties in the infrared region and significantly suppressing the angular dependence of optical characteristics.

[0087] (Optical Filter According to One Embodiment of the Present Invention)

[0088] Below, refer to Figure 2 An optical filter according to one embodiment of the present invention will be described. Figure 2 FIG. 2 schematically shows a cross section of a filter according to an embodiment of the present invention. Figure 2 As shown, an optical filter (hereinafter referred to as a “first optical filter”) 100 according to one embodiment of the present invention includes a glass substrate 110 , a first antireflection layer 120 , and a resin layer 130 containing a pigment.

[0089] The glass substrate 110 has a first main surface 112 and a second main surface 114 which are opposite to each other. The first anti-reflection layer 120 is disposed on the first main surface 112 side of the glass substrate 110. The first main surface 112 of the glass substrate 110 may be covered by the first anti-reflection layer 120, or another layer may be disposed between the first main surface 112 of the glass substrate 110 and the first anti-reflection layer 120.

[0090] At least one layer of the resin layer 130 is disposed on the second main surface 114 side of the glass substrate 110. A plurality of resin layers 130 may be stacked on the second main surface 114 side of the glass substrate 110. The first main surface 112 of the glass substrate 110 may be covered with the resin layer 130, or another layer may be disposed between the second main surface 114 of the glass substrate 110 and the resin layer 130.

[0091] From the viewpoint of protecting the glass substrate 110 from external influences, the first main surface 112 and the second main surface 114 of the glass substrate 110 are preferably covered with an inorganic film. More preferably, the first main surface 112 and the second main surface 114 of the glass substrate 110, and the end surface 116 between the first main surface 112 and the second main surface 114 are covered with an inorganic film such as aluminum oxide.

[0092] (Optical filter according to another embodiment of the present invention)

[0093] Next, refer to Figure 3 An optical filter according to another embodiment of the present invention will be described. Figure 3 Schematically shows a cross section of the structure of another embodiment of the filter of the present invention (hereinafter referred to as the "second filter"). Figure 3 As shown in FIG. 1 , the second filter 200 has the same structure as the first filter 100 described above. Figure 3 In the embodiment, for the components corresponding to the components included in the first filter 100, the components are respectively used for Figure 2 The reference numerals shown are those obtained by increasing 100.

[0094] For example, Figure 3 As shown, the second optical filter 200 includes a glass substrate 210 , a first antireflection layer 220 , and a resin layer 230 containing a pigment. However, in the second optical filter 200 , unlike the first optical filter 100 , a second antireflection layer 240 is provided on the resin layer 230 .

[0095] The first main surface 212 of the glass substrate 210 may be covered with the first anti-reflection layer 220 , or another layer may be disposed between the first main surface 212 of the glass substrate 210 and the first anti-reflection layer 220 .

[0096] At least one layer of the resin layer 230 is disposed on the second main surface 214 side of the glass substrate 210. A plurality of resin layers 230 may be stacked on the second main surface 214 side of the glass substrate 210. The second main surface 214 of the glass substrate 210 may be covered with the resin layer 230, or another layer may be disposed between the second main surface 214 of the glass substrate 210 and the resin layer 230.

[0097] From the viewpoint of protecting the glass substrate 210 from external influences, the first main surface 212 and the second main surface 214 of the glass substrate 210 are preferably covered with an inorganic film. More preferably, the first main surface 212 and the second main surface 214 of the glass substrate 210, and the end surface 216 between the first main surface 212 and the second main surface 214 are covered with an inorganic film such as aluminum oxide.

[0098] (Regarding the respective components included in the optical filter according to one embodiment of the present invention)

[0099] Next, each component constituting the optical filter according to one embodiment of the present invention will be described in more detail. Figure 2 The components will be described by taking the first optical filter 100 shown in FIG. 1 as an example. Figure 2 Reference marks shown.

[0100] (Glass substrate 110)

[0101] Hereinafter, the glass substrate 110 used in the optical filter according to one embodiment of the present invention will be described. In the following description, unless otherwise specified, the content and total content of each component represent values ​​of mass percentage based on oxides.

[0102] The glass substrate 110 is composed of phosphoric acid glass containing an absorbent. In terms of mass percentage based on oxides, the glass substrate 110 comprises:

[0103] 50% to 80% P2O5;

[0104] 5% to 20% Al2O3;

[0105] 4% to 20% CuO;

[0106] 0.5% to 15% of R(1)2O, wherein R(1) is at least one element selected from the group consisting of Li, Na, K, Rb and Cs; and

[0107] 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn.

[0108] P2O5 is a main component for forming glass and is a component for improving near-infrared cutoff. If the content of P2O5 is 50% or more, its effect can be fully obtained. If the content of P2O5 is 80% or less, it is not easy to cause problems such as glass becoming unstable and weather resistance being reduced. Therefore, P2O5 is preferably 50% to 80%, more preferably 52% to 78%, further preferably 54% to 77%, further more preferably 56% to 76%, and most preferably 60% to 75%.

[0109] Al2O3 is the main component of glass and is used to improve the strength of glass. If the content of Al2O3 is 5% or more, its effect can be fully obtained. If the content of Al2O3 is 20% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced. Therefore, Al2O3 is preferably 5% to 20%, more preferably 6% to 18%, further preferably 7% to 17%, further more preferably 8% to 16%, and most preferably 9% to 13%. If the content of Al2O3 is 9% or more, the weather resistance of glass can be improved.

[0110] R(1)2O is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, etc. If the total amount of R(1)2O is 0.5% or more, its effect can be fully obtained, and if the total amount of R(1)2O is 20% or less, the glass is less likely to become unstable, which is preferred. Therefore, the total amount of R(1)2O is preferably 0.5% to 20%, more preferably 1% to 20%, further preferably 2% to 20%, further more preferably 3% to 20%, and most preferably 4% to 20%.

[0111] Li2O is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. The content of Li2O is preferably 0% to 15%. If the content of Li2O is 15% or less, it is not easy to cause problems such as glass becoming unstable and near-infrared cutoff properties being reduced, so it is preferred. The content of Li2O is more preferably 0% to 8%, further preferably 0% to 7%, further more preferably 0% to 6%, and most preferably substantially free of Li2O.

[0112] In the present application, “substantially containing no specific component” means that the specific component is not intentionally added, and does not exclude the inclusion of the specific component to the extent that the specific component is inevitably mixed from raw materials and the like and does not affect the desired properties.

[0113] Na2O is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. The content of Na2O is preferably 0% to 15%. If the content of Na2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of Na2O is more preferably 0.5% to 14%, further preferably 1% to 13%, and further more preferably 2% to 13%.

[0114] K2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of K2O is preferably 0% to 15%. If the content of K2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of K2O is more preferably 0.5% to 14%, further preferably 1% to 13%, and further more preferably 2% to 13%.

[0115] Rb2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of Rb2O is preferably 0% to 15%. If the content of Rb2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of Rb2O is more preferably 0.5% to 14%, further preferably 1% to 13%, and further more preferably 2% to 13%.

[0116] Cs2O is a component that has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of Cs2O is preferably 0% to 15%. If the content of Cs2O is 15% or less, the glass is less likely to become unstable, so it is preferred. The content of Cs2O is more preferably 0.5% to 14%, further preferably 1% to 13%, and further more preferably 2% to 13%.

[0117] R(2)O is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, and improve the strength of glass. The total amount of R(2)O is preferably 0% to 15%. If the total amount of R(2)O is 15% or less, it is less likely to cause problems such as glass instability, reduced near-infrared cutoff, reduced short-wavelength infrared transmittance, and reduced glass strength, so it is preferred. The total amount of R(2)O is more preferably 0% to 13%, and even more preferably 0% to 11%. It is even more preferably 0% to 9%, and even more preferably 0% to 8%.

[0118] CuO is a component for cutting off near infrared rays. If the content of CuO is 4% or more, its effect can be fully obtained. In addition, if the content of CuO is 20% or less, it is not easy to produce problems such as reduced transmittance in the visible light region and reduced transmittance in the short-wavelength infrared region, so it is preferred. The content of CuO is more preferably 4% to 19.5%, further preferably 5% to 19%, further more preferably 6% to 18.5%, and further preferably greater than 7%. In particular, when the glass does not substantially contain divalent cations other than Cu, the near-infrared cutoff and short-wavelength infrared transmittance can be further improved by having a CuO content greater than 7%. The most preferred content of CuO is 7% to 18% (excluding 7%).

[0119] It is preferred that the glass substrate 110 contains substantially no divalent cations other than Cu. The reason for this will be described below.

[0120] When the glass of this embodiment contains CuO, 2+ The light absorption of the ions blocks the light in the near infrared region. 2- The electric field of the ions splits the Cu 2+ It is produced by the electron transition between the d orbitals of the ions. 2+ O around ions 2- When the symmetry of the ion is reduced, the splitting of the d orbitals is promoted. 2- When there are cations around the ion, O 2- The ions are attracted by the electric field of the cations, O 2- The symmetry of the ions is reduced. As a result, the splitting of the d orbital is promoted, and light absorption occurs through the electron transition between the split d orbitals, so the light absorption capacity in the near-infrared region is weakened, and the light absorption capacity in the short-wavelength infrared region is enhanced. When the valence of the ion is large, the intensity of the electric field of the cation becomes stronger, so especially when an oxide containing a divalent cation other than Cu is added to the glass, the near-infrared cutoff may be reduced and the transmittance of the short-wavelength infrared may be reduced.

[0121] CaO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, and increase the strength of glass. As the content of CaO, it is preferably 0% to 10%. If the content of CaO is less than 10%, it is not easy to cause problems such as glass becoming unstable, near-infrared cutoff properties being reduced, and short-wavelength infrared transmittance being reduced, so it is preferred. It is more preferably 0% to 8%, further preferably 0% to 6%, and further more preferably 0% to 5%. It is most preferred that CaO is substantially absent.

[0122] MgO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, and increase the strength of glass. The content of MgO is preferably 0% to 15%. If the content of MgO is 15% or less, it is not easy to cause problems such as glass becoming unstable, near-infrared cutoff properties being reduced, and short-wavelength infrared transmittance being reduced, so it is preferred. It is more preferably 0% to 13%, further preferably 0% to 10%, and further more preferably 0% to 9%. It is most preferred that MgO is substantially absent.

[0123] BaO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. As the content of BaO, it is preferably 0.1% to 10%. If the content of BaO is less than 10%, it is not easy to cause problems such as glass becoming unstable, near-infrared cutoff properties being reduced, and short-wavelength infrared transmittance being reduced, so it is preferred. It is more preferably 0% to 8%, further preferably 0% to 6%, and further more preferably 0% to 5%. It is most preferred that BaO is substantially absent.

[0124] SrO is a component used to lower the melting temperature of glass, lower the liquidus temperature of glass, stabilize glass, etc. The SrO content is preferably 0% to 10%. If the SrO content is 10% or less, it is not easy to cause problems such as glass becoming unstable, near-infrared cutoff properties being reduced, and short-wavelength infrared transmittance being reduced, so it is preferred. It is more preferably 0% to 8%, and even more preferably 0% to 7%. It is most preferred that SrO is substantially absent.

[0125] ZnO has the effect of lowering the melting temperature of glass and the liquidus temperature of glass. The content of ZnO is preferably 0% to 15%. If the content of ZnO is 15% or less, it is not easy to produce problems such as poor solubility of glass, reduced near-infrared cutoff, and reduced transmittance of short-wavelength infrared, so it is preferred. It is more preferably 0% to 13%, further preferably 0% to 10%, and further more preferably 0% to 9%. It is most preferred that ZnO is substantially absent.

[0126] In order to stabilize the glass, B2O3 may be contained within a range of 10% or less. If the content of B2O3 is 10% or less, it is not easy to cause problems such as poor weather resistance of the glass, reduced near-infrared cutoff, and reduced transmittance of short-wavelength infrared rays, so it is preferred. Preferably, it is 9% or less, more preferably 8% or less, further preferably 7% or less, further more preferably 6% or less, and most preferably, substantially no B2O3 is contained.

[0127] In the glass substrate 110 , F is a component effective for improving weather resistance, but is an environmentally hazardous substance and may reduce near-infrared cutoff properties, so it is preferred that F is not substantially contained.

[0128] In order to improve the weather resistance of the glass, the glass substrate 110 may contain SiO2, GeO2, ZrO2, SnO2, TiO2, CeO2, WO3, Y2O3, La2O3, Gd2O3, Yb2O3, and Nb2O5 in a range of 5% or less. If the content of these components is 5% or less, it is less likely to cause problems such as reduced near infrared cutoff and reduced short-wavelength infrared transmittance, so it is preferred. It is preferably 4% or less, more preferably 3% or less, further preferably 2% or less, and further more preferably 1% or less.

[0129] Fe2O3, Cr2O3, Bi2O3, NiO, V2O5, MoO3, MnO2, and CoO are components that reduce the visible light transmittance due to their presence in the glass. Therefore, it is preferred that these components are not substantially contained in the glass.

[0130] The thermal expansion coefficient of the glass substrate 110 in the range of 30°C to 300°C is preferably 60×10 -7 / ℃~180×10 -7 / ℃.

[0131] The glass substrate 110 may have a thickness in the range of 0.1 mm to 3 mm, for example.

[0132] The shape of the glass substrate 110 is not particularly limited. The first main surface 112 and the second main surface 114 of the glass substrate 110 may be rectangular or elliptical (including circular). When the first main surface 112 and the second main surface 114 are rectangular, the glass substrate 110 has a plurality of end surfaces 116. On the other hand, when the first main surface 112 and the second main surface 114 are circular, the glass substrate 110 has a single end surface 116.

[0133] In addition, the shape of the end surface 116 is not particularly limited. For example, the end surface 116 may have a shape extending in a direction substantially perpendicular to the first main surface 112 and the second main surface 114, or may have other shapes. For example, the end surface 116 of the glass substrate 110 may have a portion inclined relative to the normal line of the first main surface 112 and / or the normal line of the second main surface 114.

[0134] Figure 4 An example of the optical properties of the glass substrate 110 is schematically shown in FIG. Figure 4 In the figure, the horizontal axis is the wavelength and the vertical axis is the internal transmittance when the incident angle is 5°.

[0135] like Figure 4 As shown, the glass substrate 110 preferably has the following spectral characteristics:

[0136] (b-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 92%,

[0137] (b-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%,

[0138] (b-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 625nm~650nm,

[0139] (b-4) Average internal transmittance T in the wavelength range of 750 nm to 1000 nm （g）ave2 Below 2.5%,

[0140] (b-5) Maximum internal transmittance T in the wavelength range of 1000nm to 1200nm （g）max is less than 7%, and

[0141] The haze value is less than 1%.

[0142] When the glass substrate 110 has the spectral characteristics (b-1) to (b-5) and a haze value of 1% or less, the light shielding property of the first optical filter 100 in the infrared region can be significantly improved while maintaining the image clarity, and the angular dependence of the optical characteristics can be significantly suppressed. In addition, the visible light region can also be significantly improved.

[0143] (First anti-reflection layer 120)

[0144] In the present application, the “antireflection layer” refers to a layer configured so that the maximum reflectance is 45% or less for light with a wavelength between 450 nm and 1200 nm. The reflectance of the first antireflection layer in the wavelength range of 450 nm to 750 nm is preferably 20% or less.

[0145] The first anti-reflection layer 120 is composed of a multilayer film. The multilayer film can be composed of alternating films of high refractive index films and low refractive index films. The high refractive index film can be selected from titanium dioxide and aluminum oxide, for example. In addition, the low refractive index film can be selected from silicon dioxide and magnesium fluoride, for example.

[0146] The thickness of the first anti-reflection layer 120 is, for example, in the range of 0.1 μm to 3 μm, but is not limited thereto.

[0147] exist Figure 3 In the case of the second optical filter 200 shown, the first anti-reflection layer 220 and the second anti-reflection layer 240 may have the same structure as the first anti-reflection layer 120 of the first optical filter 100 .

[0148] (Resin layer 130)

[0149] The resin layer 130 contains a pigment that absorbs infrared rays. Such a pigment can be obtained, for example, from squaric acid. Choose from salt pigments, phthalocyanine pigments and anthocyanin pigments.

[0150] In addition, there is no particular limitation on the resin constituting the resin layer 130 as long as it is transparent. The resin can be selected from, for example, polyester resins, acrylic resins, epoxy resins, ene-thiol resins, polycarbonate resins, polyether resins, polyarylate resins, polysulfone resins, polyethersulfone resins, polyparaphenylene resins, polyarylene ether phosphine oxide resins, polyamide resins, polyimide resins, polyamideimide resins, polyolefin resins, cyclic olefin resins, polyurethane resins, and polystyrene resins.

[0151] From the viewpoints of spectral characteristics, glass transition temperature (Tg), and adhesion of the resin layer 130 , the resin is preferably selected from polyimide resins, polycarbonate resins, polyester resins, and acrylic resins.

[0152] In addition, from the viewpoint of heat resistance, the glass transition temperature (Tg) of the resin is preferably 200° C. or higher.

[0153] The resin contained in the resin layer 130 may be one kind or a mixture of two or more kinds.

[0154] The thickness of the resin layer 130 is 10 μm or less. The thickness of the resin layer 130 is preferably in the range of 0.3 μm to 10 μm. When the thickness of the resin layer 130 is 10 μm or less, the haze value of the filter can be reduced, and the light shielding property in the infrared region can be significantly improved while maintaining the clarity of the image.

[0155] The pigment has a maximum absorption wavelength in the range of 690 nm to 800 nm in the resin layer 130. In other words, the resin layer 130 has a maximum absorption wavelength in the range of 690 nm to 800 nm. Therefore, when the resin layer 130 including such a pigment is combined with the glass substrate 110 of the above composition, the internal transmittance in the infrared region can be reduced compared to the case of only the glass substrate 110. Therefore, the light shielding property of the first optical filter 100 in the infrared region can be significantly improved.

[0156] For example, the aforementioned square acid The maximum absorption wavelength of the salt pigment may be 752 nm, and the maximum absorption wavelength of the anthocyanin pigment may be 773 nm.

[0157] The resin layer 130 preferably has the following spectral characteristics:

[0158] (c-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 85%,

[0159] (c-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%,

[0160] (c-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 660nm~700nm.

[0161] Since the resin layer 130 has the spectral characteristics (c-1) to (c-3) described above, when the resin layer 130 is combined with the glass substrate 110 having the above composition, the light shielding property of the first optical filter 100 in the infrared region can be more significantly improved.

[0162] When the internal transmittance calculated by the above-mentioned formula (3) is represented by Y, the absorbance is represented by the following formula (4).

[0163] Absorbance = -log10 (Y / 100) …… (4)

[0164] When the absorbance at a wavelength of 450 nm is A1, the absorbance at a wavelength of 500 nm is A2, the absorbance at a wavelength of 550 nm is A3, and the absorbance at a wavelength of 600 nm is A4, the resin layer 130 preferably satisfies the following relational expression.

[0165] 0<A2 / A1

[0166] A3 / A2>1

[0167] A4 / A3>1

[0168] When the absorbance of the resin layer 130 satisfies the above relationship, the light shielding property of the first optical filter 100 in the infrared region can be more significantly improved when the resin layer 130 is combined with the glass substrate 110 having the above composition.

[0169] In addition, the resin layer 130 may have a pigment that absorbs light in the ultraviolet region. Such a pigment may be, for example, a merocyanine pigment (maximum absorption wavelength 397 nm). The resin layer 130 may have a pigment that absorbs light in the ultraviolet region, thereby being able to sufficiently suppress the internal transmittance in the ultraviolet region.

[0170] Figure 5 An example of the absorption spectrum of the resin layer 130 (more precisely, the pigment contained in the resin layer 130) is schematically shown in FIG. Figure 5 In the figure, the horizontal axis is the wavelength and the vertical axis is the internal transmittance. The resin layer 130 includes anthocyanin pigment, anthocyanin pigment and squaric acid. Salt pigments are used as pigments.

[0171] like Figure 5 As shown, in this example, the resin layer 130 shows large absorption in the wavelength region of about 400 nm and the wavelength region of about 750 nm.

[0172] (First filter 100)

[0173] Figure 6 An example of the optical characteristics of the first optical filter 100 is schematically shown in FIG. Figure 6 In the figure, the horizontal axis is wavelength and the vertical axis is transmittance.

[0174] Figure 6 The change in transmittance when the incident angle θ=0° is shown. However, in the case of the first optical filter 100, even when the incident angle θ=50°, the optical characteristics do not change much.

[0175] The first filter 100 has the following spectral characteristics:

[0176] (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%,

[0177] (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%.

[0178] (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%,

[0179] (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm.

[0180] (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at both incident angles θ = 0° and 50° （t）ave2 All are below 4.0%.

[0181] (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%.

[0182] Since the first optical filter 100 has the spectral characteristics (a-1) to (a-6) described above, the light shielding property in the infrared region can be significantly improved, and the angular dependency of the optical characteristics can be significantly suppressed.

[0183] Furthermore, the first optical filter 100 preferably has the following spectral characteristics: when light is incident from the first main surface 112 of the glass substrate 110,

[0184] (a-7) Maximum reflectivity R in the wavelength range of 450nm to 700nm at both incident angles θ = 5° and 50° （t）max1 All below 7%.

[0185] (a-8) Maximum reflectivity R in the wavelength range of 700nm to 1200nm at both incident angles θ = 5° and 50° （t）max2 All are below 45%.

[0186] Since the first optical filter 100 has the spectral characteristics (a-7) to (a-8) described above, the light shielding property in the infrared region can be significantly improved, and the angular dependency of the optical characteristics can be more significantly suppressed.

[0187] The haze value of the first optical filter 100 is 2% or less. When the haze value of the first optical filter 100 is 2% or less, the light shielding property in the infrared region can be significantly improved while maintaining the clarity of the image.

[0188] When the transmittance (%) is T and the reflectance (%) is R, the absorptivity is expressed by the following formula (1).

[0189] Absorption rate (%) = 100-TR …… (1)

[0190] In other words, the absorption rate represented by the formula (1) is the loss rate of transmittance caused by absorption of the filter.

[0191] The first optical filter 100 preferably has the following spectral characteristics: when light is incident from the first main surface 112 of the glass substrate 110,

[0192] (a-9) The average absorptivity at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 450 nm to 600 nm is 15% or less,

[0193] (a-10) The average absorption rate at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 600 nm to 1200 nm is 88% or more.

[0194] The first optical filter 100 has the spectral characteristics of (a-9) to (a-10) above. The smaller the haze value, the smaller the reflectivity. The smaller the reflectivity, the closer the absorptivity is to 100-T. （5） That is, the light shielding property in the infrared region is not caused by reflection, but the light shielding property caused by absorption contributes significantly. Therefore, the light shielding property in the infrared region can be more significantly improved while maintaining the clarity of the image.

[0195] The first optical filter 100 more preferably has the following spectral characteristics:

[0196] (a-11) the difference between the absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 450nm to 600nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 450nm to 600nm is 3% or less,

[0197] (a-12) The difference between the absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 600 nm to 1200 nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 600 nm to 1200 nm is 5% or less.

[0198] Since the first optical filter 100 has the spectral characteristics (a-11) to (a-12) described above, the light shielding property in the infrared region can be more significantly improved while maintaining the clarity of an image, and the angular dependency of the optical characteristics can be more significantly suppressed.

[0199] When the absorbance calculated by the above-mentioned formula (1) is represented by X, the absorbance is represented by the following formula (2).

[0200] Absorbance = -log10 (X / 100) …… (2)

[0201] When the incident angle θ=0°, the reflection angle θ=5°, the absorbance at a wavelength of 450nm is set to B1, the absorbance at a wavelength of 500nm is set to B2, the absorbance at a wavelength of 550nm is set to B3, and the absorbance at a wavelength of 600nm is set to B4, the first filter 100 preferably satisfies the following relationship.

[0202] 1<B2 / B1

[0203] 0<B3 / B2<1

[0204] 0<B4 / B3<1

[0205] The light shielding property in the infrared region can be more significantly improved by the first optical filter 100 satisfying the above relational expression. In addition, since the minimum value of the absorbance of the first optical filter 100 is in the green wavelength band, it can have a spectral characteristic closer to human visual sensitivity.

[0206] (Method for Manufacturing an Optical Filter According to One Embodiment of the Present Invention)

[0207] Next, an example of a method for manufacturing an optical filter according to an embodiment of the present invention will be described.

[0208] A method for manufacturing an optical filter according to an embodiment of the present invention (hereinafter referred to as “the first method”) includes the following steps: a step of preparing a glass substrate having a predetermined size (step S110); and a step of providing a first anti-reflection layer on a first main surface of the glass substrate and providing a resin layer on a second main surface of the glass substrate (step S120).

[0209] Each process is described below. It should be noted that, here, the manufacturing method of the first optical filter 100 is described by taking the first optical filter 100 as an example. Therefore, when representing each component, the Figure 2 Reference marks shown.

[0210] (Process S110)

[0211] First, a glass substrate is prepared. As described above, the glass substrate 110 has the first main surface 112, the second main surface 114, and the end surface 116, and is made of phosphoric acid glass having the above-mentioned composition.

[0212] (Process S120)

[0213] The first anti-reflection layer 120 is provided on the first main surface 112 of the glass substrate 110, and a resin layer 130 containing a pigment is provided on the second main surface 114. The resin layer 130 is formed by a resin solution containing a pigment. The resin solution can be prepared by dissolving the pigment in a solution containing a resin, an organic solvent and a silane coupling agent. The pigment can include the aforementioned infrared absorbing pigment and the ultraviolet absorbing pigment. The resin layer 130 is coated by a coating method such as a spin coating method. Then, the coated film is dried to form the resin layer 130.

[0214] In the case of the second optical filter 200 , step S130 may be further included.

[0215] (Process S130)

[0216] The second anti-reflection layer 240 is provided on the resin layer 230 .

[0217] As described above, the first anti-reflection layer 120 and the second anti-reflection layer 240 are composed of a plurality of films. The first anti-reflection layer 120 and the second anti-reflection layer 240 can be formed by alternately forming a high refractive index film and a low refractive index film. There is no particular limitation on the film forming method of the first anti-reflection layer 120 and the second anti-reflection layer 240. For example, a common film forming method such as a sputtering method can be used.

[0218] In addition, step S140 may be provided between step S110 and step S120 .

[0219] (Process S140)

[0220] An inorganic film is provided on the first main surface 112 and the second main surface 114 of the glass substrate 110. The inorganic film may be made of, for example, aluminum oxide. There is no particular limitation on the method for forming the inorganic film. The inorganic film may be formed by, for example, vapor deposition or sputtering.

[0221] The optical filter according to one embodiment of the present invention can be applied to, for example, an imaging device such as a digital camera. The imaging device having the optical filter according to one embodiment of the present invention can provide good color reproducibility.

[0222] An imaging device having an optical filter according to an embodiment of the present invention further has a solid-state imaging element and an imaging lens, and the optical filter can be arranged, for example, between the imaging lens and the solid-state imaging element. In addition, the optical filter according to an embodiment of the present invention can be directly attached to the solid-state imaging element and / or the imaging lens of the imaging device, for example, via an adhesive layer.

[0223] Example

[0224] Hereinafter, examples of the present invention will be described. It should be noted that in the following description, examples 1 and 2 are examples.

[0225] First, a glass plate was cut by a blade cutting method to prepare glass substrates A and B having a length of 76 mm × a width of 76 mm × a thickness of 0.28 mm used in Examples 1 and 2. Glass substrates A and B were phosphate glasses having the compositions shown in Table 1 below.

[0226] [Table 1]

[0227]

[0228] The optical properties of the glass substrate A and glass substrate B used are shown in the above Figure 4 In addition, various parameters calculated based on the measured optical characteristics are shown in Table 2 below.

[0229] [Table 2]

[0230]

[0231] The haze values ​​of the glass substrate A and the glass substrate B were measured in accordance with JIS K7136 using an automatic haze meter (TC-HIIIDPK) manufactured by Tokyo Denshoku Co., Ltd., and the results were both 0.1 or less.

[0232] (Example 1)

[0233] The first antireflection layer was formed on the first main surface of the glass substrate A by evaporation. The first antireflection layer was an alternating film of silicon dioxide film and titanium dioxide film. The thickness of the first antireflection layer was 200 nm. The composition of the first antireflection layer is shown in Table 3 below.

[0234] [Table 3]

[0235]

[0236] In Table 3, the first film is the film closest to the first main surface of the glass substrate A, and the second film, the third film, ..., the fifteenth film are arranged in order from near to far from the first main surface.

[0237] Next, a resin layer liquid is prepared. The resin layer liquid is prepared in the following manner.

[0238] First, polyimide varnish C3G30G (manufactured by Mitsubishi Gas Chemical Co., Ltd.) was diluted with cyclohexanone and γ-butyrolactone so that the resin solid content was 8.5% by weight. Compound A, compound B, and compound C were added as pigments to the diluted solution to prepare a liquid for a resin layer. The addition amounts of compound A, compound B, and compound C were 2.33% by mass, 6.08% by mass, and 2.56% by mass, respectively, relative to the resin.

[0239] The specifications of compound A, compound B, and compound C are collectively shown in Table 4 below.

[0240] [Table 4]

[0241]

[0242] Compound A, compound B and compound C have the following general formulae, respectively.

[0243]

[0244]

[0245]

[0246] Next, a resin layer liquid is spin-coated on the second main surface of the glass substrate A. The target thickness is 1 μm. Then, the resin layer liquid is dried to form a resin layer. The resin layer has the above-mentioned Figure 5 Optical properties shown.

[0247] Next, a second antireflection layer was formed on the resin layer. The second antireflection layer had the same structure as the first antireflection layer and was formed by a vapor deposition method. Thus, an optical filter (hereinafter referred to as “optical filter 1”) was obtained.

[0248] (Example 2)

[0249] A first aluminum oxide film was formed on the first main surface of the glass substrate B by vapor deposition. The target thickness of the first aluminum oxide film was 143 nm. Next, a second aluminum oxide film was formed on the first main surface of the glass substrate B. The target thickness of the second aluminum oxide film was 143 nm.

[0250] Next, a first antireflection layer was formed on the first aluminum oxide film by vapor deposition. The structure and thickness of the first antireflection layer were the same as those in Example 1.

[0251] Next, a resin layer liquid was spin-coated on the second aluminum oxide film of the glass substrate B. The resin layer liquid used was the same liquid as in Example 1. The target thickness of the resin layer was 1 μm. Then, the resin layer liquid was dried to form the same resin layer as in Example 1.

[0252] Next, a second antireflection layer was formed on the resin layer in the same manner as in Example 1. Thus, an optical filter (hereinafter referred to as “optical filter 2”) was obtained.

[0253] (evaluate)

[0254] The following evaluations were performed using each filter.

[0255] (Determination of haze value)

[0256] The haze value of each filter was measured in accordance with JIS K 7136. The haze values ​​of both filter 1 and filter 2 were 1% or less.

[0257] (Evaluation of optical properties)

[0258] The optical properties were evaluated using each filter. An ultraviolet-visible-near-infrared spectrophotometer (UH4150: manufactured by Hitachi High-Technologies Corporation) was used for the measurement. When measuring the transmittance, light was incident on each filter from the first anti-reflection layer side at an incident angle of 0° and 50°. On the other hand, when measuring the reflectance, light was incident on each filter from the first anti-reflection layer side at an incident angle of 5° and 50°.

[0259] exist Figure 7 An example of a transmittance curve obtained by the filter 1 is shown in FIG. Figure 7 In the figure, the horizontal axis is wavelength and the vertical axis is transmittance. Figure 7 The results when the incident angles θ=0° and θ=50° are also shown.

[0260] like Figure 7As shown in the figure, it can be seen that the influence of the incident angle θ on the transmittance curve of the filter 1 is hardly observed. That is, in the visible light region, high transmittance is obtained regardless of the incident angle θ. In addition, even if the incident angle θ changes, the area where the transmittance sharply decreases hardly changes. Furthermore, it can be seen that low transmittance is shown in the infrared region regardless of the incident angle θ.

[0261] exist Figure 8 An example of a reflectance curve obtained by filter 1 is shown in FIG. Figure 8 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 8 The results when the incident angles θ=5° and θ=50° are also shown.

[0262] like Figure 8 As shown, it can be seen that for filter 1, the influence of the incident angle θ on the reflectivity curve is almost unobservable.

[0263] exist Fig. 9 An example of a transmittance curve obtained by filter 2 is shown in FIG. Fig. 9 In the figure, the horizontal axis is wavelength and the vertical axis is transmittance. Fig. 9 The results when the incident angles θ=0° and θ=50° are also shown.

[0264] like Fig. 9 As shown in FIG. 1 , filter 2 also obtained the same results as filter 1. That is, in the visible light region, high transmittance was obtained regardless of the incident angle θ. In addition, even if the incident angle θ changes, the area where the transmittance sharply decreases does not change. Moreover, it can be seen that low transmittance is shown in the infrared region regardless of the incident angle θ.

[0265] Table 5 below shows together the parameters related to the transmittance graphs measured for the optical filter 1 and the optical filter 2.

[0266] [Table 5]

[0267]

[0268] Table 6 below shows together the parameters related to the reflectance graphs measured for Filter 1 and Filter 2.

[0269] [Table 6]

[0270]

[0271] Table 7 below shows parameters related to the absorbance graphs measured and calculated for Filter 1 and Filter 2.

[0272] [Table 7]

[0273]

[0274] Table 8 below shows parameters related to the absorbance graphs measured and calculated for Filter 1 and Filter 2.

[0275] [Table 8]

[0276]

[0277] As can be seen, for filter 1 and filter 2, it was confirmed that the optical characteristics hardly changed even when the incident angle θ changed. In addition, for filter 1 and filter 2, it was confirmed that they had excellent light absorption capabilities in the infrared region and infrared rays were fully shielded. In addition, for filter 1 and filter 2, it was confirmed that the haze value was low, and there was no problem with the clarity of the image obtained by filter 1 and filter 2.

[0278] (Mode of the Invention)

[0279] The present invention includes the following aspects.

[0280] (Method 1)

[0281] A filter, wherein the filter comprises:

[0282] a glass substrate having a first main surface and a second main surface opposite to each other and comprising phosphoric acid glass;

[0283] a first anti-reflection layer, the first anti-reflection layer being disposed on the first main surface side of the glass substrate; and

[0284] a resin layer, the resin layer containing a pigment, and at least one layer of the resin layer is arranged on the second main surface side of the glass substrate,

[0285] Calculated by mass percentage based on oxides, the glass substrate comprises:

[0286] 50% to 80% P2O5;

[0287] 5% to 20% Al2O3;

[0288] 4% to 20% CuO;

[0289] 0.5% to 15% of R(1)2O, wherein R(1) is at least one element selected from the group consisting of Li, Na, K, Rb and Cs; and

[0290] 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn,

[0291] The pigment has a maximum absorption wavelength in the resin layer within a wavelength range of 690 nm to 800 nm.

[0292] The thickness of the resin layer is less than 10 μm,

[0293] The filter has the following spectral characteristics:

[0294] (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%,

[0295] (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%.

[0296] (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%,

[0297] (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm.

[0298] (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at both incident angles θ = 0° and 50° （t）ave2 All are below 4.0%.

[0299] (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%.

[0300] The haze value of the filter is less than 2%.

[0301] (Method 2)

[0302] The optical filter according to aspect 1 has the following spectral characteristics: when light is incident from the first main surface side of the glass substrate,

[0303] (a-7) Maximum reflectivity R in the wavelength range of 450nm to 700nm at both incident angles θ = 5° and 50° （t）max1 All below 7%.

[0304] (a-8) Maximum reflectivity R in the wavelength range of 700nm to 1200nm at both incident angles θ = 5° and 50°（t）max2 All are below 45%.

[0305] (Method 3)

[0306] The optical filter according to aspect 1 or 2, wherein a second antireflection layer is disposed on the second main surface side of the glass substrate.

[0307] (Method 4)

[0308] The optical filter according to aspect 3, wherein the second main surface of the glass substrate is covered with the resin layer,

[0309] The resin layer has a maximum absorption wavelength within a wavelength range of 650nm to 850nm.

[0310] The second anti-reflection layer is disposed on the resin layer.

[0311] (Method 5)

[0312] The optical filter according to any one of aspects 1 to 4, wherein, when transmittance (%) is T and reflectance (%) is R, the absorptivity is represented by the following formula (1):

[0313] Absorption rate (%) = 100-TR …… (1)

[0314] The optical filter has the following spectral characteristics: when light is incident from the first main surface side of the glass substrate,

[0315] (a-9) The average absorptivity at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 450 nm to 600 nm is 15% or less,

[0316] (a-10) The average absorption rate at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 600 nm to 1200 nm is 88% or more.

[0317] (Method 6)

[0318] The optical filter as described in mode 5, wherein the optical filter has the following spectral characteristics:

[0319] (a-11) the difference between the average absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 450nm to 600nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 450nm to 600nm is 3% or less,

[0320] (a-12) The difference between the average absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 600 nm to 1200 nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 600 nm to 1200 nm is 5% or less.

[0321] (Method 7)

[0322] The optical filter according to any one of aspects 1 to 6, wherein, when transmittance (%) is T and reflectance (%) is R,

[0323] The absorption rate is expressed by the following formula (1):

[0324] Absorption rate (%) = 100-TR …… (1)

[0325] When the absorption rate calculated by the above formula (1) is set to X,

[0326] The absorbance is expressed by the following formula (2):

[0327] Absorbance = -log10 (X / 100) …… (2)

[0328] When the incident angle θ=0°, the reflection angle θ=5°, the absorbance at a wavelength of 450nm is set to B1, the absorbance at a wavelength of 500nm is set to B2, the absorbance at a wavelength of 550nm is set to B3, and the absorbance at a wavelength of 600nm is set to B4, the filter satisfies the following relationship:

[0329] 1<B2 / B1

[0330] 0<B3 / B2<1

[0331] 0<B4 / B3<1.

[0332] (Method 8)

[0333] The optical filter according to any one of aspects 1 to 7, wherein the transmittance (%) at an incident angle of 5° is T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） hour,

[0334] The internal transmittance is expressed by the following formula (3):

[0335] Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3)

[0336] The glass substrate has the following spectral characteristics:

[0337] (b-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 92%,

[0338] (b-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%,

[0339] (b-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 625nm~650nm,

[0340] (b-4) Average internal transmittance T in the wavelength range of 750 nm to 1000 nm （g）ave2 Below 2.5%,

[0341] (b-5) Maximum internal transmittance T in the wavelength range of 1000nm to 1200nm （g）max Below 7%,

[0342] The haze value of the glass substrate is less than 1%.

[0343] (Method 9)

[0344] The optical filter according to any one of aspects 1 to 8, wherein the transmittance (%) at an incident angle of 5° is T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） hour,

[0345] The internal transmittance is expressed by the following formula (3):

[0346] Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3)

[0347] The resin layer has the following spectral characteristics:

[0348] (c-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 85%,

[0349] (c-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%,

[0350] (c-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 660nm~700nm.

[0351] (Method 10)

[0352] The optical filter according to any one of aspects 1 to 9, wherein the transmittance (%) at an incident angle of 5° is T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） hour,

[0353] The internal transmittance is expressed by the following formula (3):

[0354] Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3)

[0355] When the internal transmittance calculated by equation (3) is set to Y,

[0356] The absorbance is expressed by the following formula (4):

[0357] Absorbance = -log10 (Y / 100) …… (4)

[0358] When the absorbance at a wavelength of 450 nm is set to A1, the absorbance at a wavelength of 500 nm is set to A2, the absorbance at a wavelength of 550 nm is set to A3, and the absorbance at a wavelength of 600 nm is set to A4, the resin layer satisfies the following relationship:

[0359] 0<A2 / A1

[0360] A3 / A2>1

[0361] A4 / A3>1.

[0362] (Method 11)

[0363] The optical filter according to any one of aspects 1 to 10, wherein the first main surface and the second main surface of the glass substrate are covered with an inorganic film.

[0364] (Method 12)

[0365] An imaging device, wherein the imaging device comprises the filter according to any one of aspects 1 to 11.

[0366] This international application claims the priority based on Japanese Patent Application No. 2022-102257 filed on June 24, 2022, the entire contents of which are incorporated herein by reference.

[0367] Description of symbols

[0368] 100 1st filter

[0369] 110 Glass substrate

[0370] 112 1st main surface

[0371] 114 Second main surface

[0372] 116 End face

[0373] 120 1st anti-reflection layer

[0374] 130 resin layer

[0375] 200 2nd filter

[0376] 210 Glass substrate

[0377] 212 1st main surface

[0378] 214 Second main surface

[0379] 216 End face

[0380] 220 1st anti-reflection layer

[0381] 230 resin layer

[0382] 240 Second anti-reflection layer

Claims

1. A filter, wherein: The optical filter has: a glass substrate having a first main surface and a second main surface opposite to each other and comprising phosphoric acid glass; a first anti-reflection layer, the first anti-reflection layer being disposed on the first main surface side of the glass substrate; and a resin layer, the resin layer containing a pigment, and at least one layer being arranged on the second main surface side of the glass substrate, Calculated by mass percentage based on oxides, the glass substrate comprises: 50% to 80% P2O5; 5% to 20% Al2O3; 4% to 20% CuO; 0.5% to 15% of R(1)2O, wherein R(1) is at least one element selected from the group consisting of Li, Na, K, Rb and Cs; and 0% to 15% of R(2)O, wherein R(2) is at least one component selected from the group consisting of Ca, Mg, Ba, Sr and Zn, The pigment has a maximum absorption wavelength in the resin layer within a wavelength range of 690 nm to 800 nm. The thickness of the resin layer is less than 10 μm, The filter has the following spectral characteristics: (a-1) Transmittance T at a wavelength of 450 nm when the incident angle θ = 0° and 50° （t）450 All are above 80%, (a-2) Average transmittance T in the wavelength range of 450nm to 600nm at the two cases of incident angle θ = 0° and 50° （t）ave1 All of them are above 78%. (a-3) Maximum transmittance T in the wavelength range of 450nm to 600nm at both incident angles θ = 0° and 50° （t）max1 All are above 85%, (a-4) The minimum wavelength λ when the transmittance is 50% for the two cases of incident angle θ = 0° and 50° （t）50 All are in the range of 600nm to 650nm. (a-5) Average transmittance T in the wavelength range of 750nm to 1200nm at the two cases of incident angle θ = 0° and 50° （t）ave2 All are below 4.0%. (a-6) Maximum transmittance T in the wavelength range of 1000nm to 1200nm at both incident angles θ = 0° and 50° （t）max2 All below 15%. The haze value of the filter is less than 2%.

2. The optical filter according to claim 1, wherein: The filter has the following spectral characteristics: When light is incident on the first main surface of the glass substrate, (a-7) Maximum reflectivity R in the wavelength range of 450nm to 700nm at both incident angles θ = 5° and 50° （t）max1 All below 7%. (a-8) Maximum reflectivity R in the wavelength range of 700nm to 1200nm at both incident angles θ = 5° and 50° （t）max2 All below 45%.

3. The optical filter according to claim 1 or 2, wherein: A second antireflection layer is disposed on the second main surface side of the glass substrate.

4. The optical filter according to claim 3, wherein: The second main surface of the glass substrate is covered with the resin layer, The resin layer has a maximum absorption wavelength within a wavelength range of 650nm to 850nm. The second anti-reflection layer is disposed on the resin layer.

5. The optical filter according to claim 3, wherein: When the transmittance (%) is T and the reflectance (%) is R, the absorptivity is expressed by the following formula (1): Absorption rate (%) = 100-TR …… (1) The filter has the following spectral characteristics: When light is incident on the first main surface of the glass substrate, (a-9) The average absorptivity at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 450 nm to 600 nm is 15% or less, (a-10) The average absorption rate at an incident angle θ=0° and a reflection angle θ=5° within a wavelength range of 600 nm to 1200 nm is 88% or more.

6. The optical filter according to claim 5, wherein: The filter has the following spectral characteristics: (a-11) the difference between the average absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 450nm to 600nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 450nm to 600nm is 3% or less, (a-12) The difference between the average absorptivity at an incident angle θ=0° and a reflection angle θ=5° in a wavelength range of 600 nm to 1200 nm and the average absorptivity at an incident angle θ=50° and a reflection angle θ=50° in a wavelength range of 600 nm to 1200 nm is 5% or less.

7. The optical filter according to claim 6, wherein: When the absorption rate calculated by the above formula (1) is set to X, The absorbance is expressed by the following formula (2): Absorbance = -log10 (X / 100) …… (2) When the incident angle θ=0°, the reflection angle θ=5°, the absorbance at a wavelength of 450nm is set to B1, the absorbance at a wavelength of 500nm is set to B2, the absorbance at a wavelength of 550nm is set to B3, and the absorbance at a wavelength of 600nm is set to B4, the filter satisfies the following relationship: 1<B2 / B1 0<B3 / B2<1 0<B4 / B3<1.

8. The optical filter according to claim 1 or 2, wherein: When the incident angle is 5°, the transmittance (%) is set to T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） hour, The internal transmittance is expressed by the following formula (3): Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3) The glass substrate has the following spectral characteristics: (b-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 92%, (b-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%, (b-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 625nm~650nm, (b-4) Average internal transmittance T in the wavelength range of 750 nm to 1000 nm （g）ave2 Below 2.5%, (b-5) Maximum internal transmittance T in the wavelength range of 1000nm to 1200nm （g）max Below 7%, The haze value of the glass substrate is less than 1%.

9. The optical filter according to claim 1 or 2, wherein: When the incident angle is 5°, the transmittance (%) is set to T （5） , let the reflectivity (%) when the incident angle is 5° be R （5） hour, The internal transmittance is expressed by the following formula (3): Internal transmittance (%) = T （5） / (100-R （5） ) × 100 …… (3) The resin layer has the following spectral characteristics: (c-1) Internal transmittance T at a wavelength of 450 nm （g）450 More than 85%, (c-2) Average internal transmittance T in the wavelength range of 450 nm to 600 nm （g）ave1 More than 90%, (c-3) Minimum wavelength λ when internal transmittance is 50% （g）50 In the range of 660nm~700nm.

10. The optical filter according to claim 9, wherein: When the internal transmittance calculated by the above formula (3) is denoted as Y, The absorbance is expressed by the following formula (4): Absorbance = -log10 (Y / 100) …… (4) When the absorbance at a wavelength of 450 nm is A1, the absorbance at a wavelength of 500 nm is A2, the absorbance at a wavelength of 550 nm is A3, and the absorbance at a wavelength of 600 nm is A4, the resin layer satisfies the following relationship: 0<A2 / A1 A3 / A2>1 A4 / A3>1.

11. The optical filter according to claim 1 or 2, wherein: The first main surface and the second main surface of the glass substrate are covered with an inorganic film.

12. An imaging device, wherein: The imaging device comprises the optical filter according to claim 1 or 2.

Images