Near-infrared cut-off filter

Abstract

A near-infrared cut filter capable of intentionally suppressing reflectivity in the visible light region over a wide range of incident angles. The near-infrared cut filter comprises a transparent substrate, an optical multilayer film, a first matching film, and an outermost second matching film, the first matching film being disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film. In this near-infrared cut filter, the regular reflectance of light incident from the second matching film at an incident angle of 5° is defined as first reflectance R1, and the regular reflectance of light incident at an incident angle of 40° is defined as second reflectance R2. When an approximate straight line for R1 in the wavelength range of 480 nm to 680 nm is defined as y1, and an approximate straight line for R2 in the wavelength range of 450 nm to 650 nm is defined as y2, the maximum absolute value ΔR1 of the difference between the values of R1 and y1 is less than 5%, and the maximum absolute value ΔR2 of the difference between the values of R2 and y2 is less than 6%.

Description

Technical Field

[0001] The present invention relates to a near-infrared cut filter. Background Art

[0002] Imaging devices such as digital cameras and camcorders are equipped with solid-state imaging devices (image sensors) to detect people and scenery. However, solid-state imaging devices exhibit a higher sensitivity to infrared light than human vision. Therefore, to make images produced by solid-state imaging devices approach human visual sensitivity, imaging devices are also equipped with near-infrared cutoff filters.

[0003] Typically, such near-infrared cut filters are constructed by placing an optical multilayer film that shields near-infrared rays on a transparent substrate. The optical multilayer film is constructed by alternately stacking thin films composed of a high-refractive-index dielectric (e.g., TiO2) and thin films composed of a low-refractive-index dielectric (e.g., SiO2).

[0004]

Prior technical literature

[0005] [Patent Literature]

[0006] [Patent Document 1] International Publication No. WO2014 / 104370

[0007] [Problems to be solved by the invention]

[0008] It is known that the optical properties of near-infrared cut filters having optical multilayers often vary depending on the angle of incident light. This can lead to problems such as achieving desired optical properties for light with an incident angle close to normal, but failing to achieve desired optical properties for light with an incident angle significantly deviating from normal.

[0009] Furthermore, the incident angle dependence of the optical properties of such near-infrared cut filters poses a problem in image clarity when applied to solid-state imaging devices. For example, if some visible light entering the near-infrared cut filter is not transmitted but reflected, this reflected light can cause stray light. Summary of the Invention

[0010] The present invention has been made in view of the above background, and an object of the present invention is to provide a near-infrared cut filter capable of intentionally suppressing the reflectance in the visible light region within a wide range of incident angles.

[0011]

Solutions to Solve the Problem

[0012] The present invention provides a near-infrared cut filter, comprising:

[0013] a transparent substrate having a first surface;

[0014] an optical multilayer film disposed on the first surface side of the transparent substrate;

[0015] a first matching film, disposed on the first surface side of the transparent substrate;

[0016] a second matching film, disposed on the outermost side of the first surface;

[0017] The optical multilayer film has a structure in which high-refractive index layers and low-refractive index layers are alternately stacked, and the optical multilayer film has a function of reflecting near-infrared rays.

[0018] The first matching film and the second matching film have the function of suppressing the reflection of visible light.

[0019] The first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film.

[0020] In this near infrared cut filter,

[0021] The regular reflectance of light incident from the second matching film side at an incident angle of 5° is defined as a first reflectance R1, and the regular reflectance of light incident from the second matching film side at an incident angle of 40° is defined as a second reflectance R2.

[0022] When the approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm is y1 and the approximate straight line of the second reflectance R2 in the wavelength range of 450nm to 650nm is y2,

[0023] In the wavelength range of 480 nm to 680 nm, the maximum absolute value ΔR1 of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%.

[0024] In the wavelength range of 450 nm to 650 nm, the maximum value ΔR2 of the absolute value of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%.

[0025] Effects of the invention

[0026] The present invention can provide a near-infrared cut filter capable of intentionally suppressing the reflectance in the visible light region within a wide incident angle range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a diagram schematically showing a cross section of a near-infrared cut filter according to one embodiment of the present invention.

[0028] Figure 2 This is a diagram schematically showing a cross section of a near-infrared cut filter according to another embodiment of the present invention.

[0029] Figure 3 This is a diagram schematically showing a cross section of a near-infrared cut filter according to still another embodiment of the present invention.

[0030] Figure 4 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 1 at 5° incidence and 40° incidence.

[0031] Figure 5 It will Figure 4 A graph showing an enlarged portion of the optical characteristics at an incident angle of 5°.

[0032] Figure 6 It will Figure 4 A graph showing an enlarged portion of the optical characteristics at 40° incidence.

[0033] Figure 7 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 2 at 5° incidence and 40° incidence.

[0034] Figure 8 It will Figure 7 A graph showing an enlarged portion of the optical characteristics at an incident angle of 5°.

[0035] Figure 9 It will Figure 7 A graph showing an enlarged portion of the optical characteristics at 40° incidence.

[0036] Figure 10 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 3 at 5° incidence and 40° incidence.

[0037] Figure 11 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 4 at 5° incidence and 40° incidence.

[0038] Figure 12 It will Figure 11 A graph showing an enlarged portion of the optical characteristics at an incident angle of 5°.

[0039] Figure 13 It will Figure 11 A graph showing an enlarged portion of the optical characteristics at 40° incidence.

[0040] Figure 14This is a graph showing the optical characteristics of the near-infrared cut filter of Example 11 at 5° incidence and 40° incidence.

[0041] Figure 15 It will Figure 14 A graph showing an enlarged portion of the optical characteristics at an incident angle of 5°.

[0042] Figure 16 It will Figure 14 A graph showing an enlarged portion of the optical characteristics at 40° incidence.

[0043] Figure 17 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 11 at 5° incidence and 40° incidence.

[0044] Figure 18 It will Figure 17 A graph showing an enlarged portion of the optical characteristics at an incident angle of 5°.

[0045] Figure 19 It will Figure 17 A graph showing an enlarged portion of the optical characteristics at 40° incidence.

[0046] Figure 20 This is a graph showing the optical characteristics of the near-infrared cut filter of Example 13 at 5° incidence and 40° incidence.

[0047] Figure 21 This is a graph showing the optical characteristics obtained in the near-infrared cut filter of Example 14 at 5° incidence and 40° incidence.

[0048]

Number Description

[0049] 100 First Optical Filter

[0050] 110 Transparent substrate

[0051] 112 first surface

[0052] 120 optical multilayer film

[0053] 140 first matching film

[0054] 160 Second matching film

[0055] 200 Second optical filter

[0056] 210 transparent substrate

[0057] 212 first surface

[0058] 220 optical multilayer film

[0059] 240 First matching film

[0060] 260 Second matching film

[0061] 300 Third optical filter

[0062] 310 transparent substrate

[0063] 312 first surface

[0064] 320 optical multilayer film

[0065] 340 First Matching Film

[0066] 350 Third matching film

[0067] 360 Second Matching Film DETAILED DESCRIPTION

[0068] Hereinafter, one embodiment of the present invention will be described.

[0069] In one embodiment of the present invention, a near-infrared cut filter is provided, comprising:

[0070] a transparent substrate having a first surface;

[0071] an optical multilayer film disposed on the first surface side of the transparent substrate;

[0072] a first matching film, disposed on the first surface side of the transparent substrate;

[0073] a second matching film, disposed on the outermost side of the first surface;

[0074] The optical multilayer film has a structure in which high-refractive index layers and low-refractive index layers are alternately stacked, and the optical multilayer film has a function of reflecting near-infrared rays.

[0075] The first matching film and the second matching film have the function of suppressing the reflection of visible light.

[0076] The first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film.

[0077] In this near infrared cut filter,

[0078] The regular reflectance of light incident from the second matching film side at an incident angle of 5° is defined as a first reflectance R1, and the regular reflectance of light incident from the second matching film side at an incident angle of 40° is defined as a second reflectance R2.

[0079] When the approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm is y1 and the approximate straight line of the second reflectance R2 in the wavelength range of 450nm to 650nm is y2,

[0080] In the wavelength range of 480 nm to 680 nm, the maximum absolute value ΔR1 of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%.

[0081] In the wavelength range of 450 nm to 650 nm, the maximum value ΔR2 of the absolute value of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%.

[0082] A near-infrared cut filter according to one embodiment of the present invention includes an optical multilayer film having a function of preventing transmission of near-infrared rays and reflecting the near-infrared rays.

[0083] Furthermore, the near infrared cut filter according to one embodiment of the present invention includes a first matching film and a second matching film. The first matching film and the second matching film have a function of suppressing reflection of visible light.

[0084] Furthermore, the near-infrared cut filter according to one embodiment of the present invention is characterized in that, within the wavelength range of 480 nm to 680 nm, the maximum absolute value ΔR1 of the difference between the first reflectivity R1 at the same wavelength and the value of the approximate straight line y1 is less than 5%. Furthermore, the near-infrared cut filter according to one embodiment of the present invention is characterized in that, within the wavelength range of 450 nm to 650 nm, the maximum absolute value ΔR2 of the difference between the second reflectivity R2 at the same wavelength and the value of the approximate straight line y2 is less than 6%.

[0085] As will be described in detail later, a near-infrared cut filter having such a structure can intentionally suppress the reflectivity in the visible light region over a wide range of incident angles. Therefore, when the near-infrared cut filter according to one embodiment of the present invention is applied to a solid-state imaging element, a clear image can be obtained.

[0086] (Near-infrared cut filter according to one embodiment of the present invention)

[0087] Next, one embodiment of the present invention will be described in more detail with reference to the drawings.

[0088] Figure 1 A cross section of a near-infrared cut filter (hereinafter referred to as a “first optical filter”) according to one embodiment of the present invention is schematically shown.

[0089] like Figure 1As shown, the first optical filter 100 includes: a transparent substrate 110 having a first surface 112 ; an optical multilayer film 120 ; a first matching film 140 ; and a second matching film 160 .

[0090] The optical multilayer film 120 is disposed on the first surface 112 of the transparent substrate 110 , and the first matching film 140 is disposed on the optical multilayer film 120 . Furthermore, the second matching film 160 is disposed on the outermost side of the first surface 112 .

[0091] The optical multilayer film 120 has a function of preventing the transmission of near-infrared rays and reflecting the near-infrared rays. Furthermore, the first matching film 140 and the second matching film 160 have a function of suppressing the reflection of visible light.

[0092] Here, the regular reflectance of light incident from the second matching film 160 side at an incident angle of 5° relative to the normal is referred to as first reflectance R1, and the regular reflectance of light incident at an incident angle of 40° relative to the normal is referred to as second reflectance R2. Furthermore, the approximate straight line for the first reflectance R1 in the wavelength range of 480 nm to 680 nm is denoted as y1, and the approximate straight line for the second reflectance R2 in the wavelength range of 450 nm to 650 nm is denoted as y2.

[0093] In this case, the first optical filter 100 has the following features:

[0094] In the wavelength range of 480 nm to 680 nm, the maximum value ΔR1 of the absolute value of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%.

[0095] In the wavelength range of 450 nm to 650 nm, the maximum value ΔR2 of the absolute value of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%.

[0096] For example, ΔR1 may be less than 4%, preferably less than 3%. Furthermore, for example, ΔR2 may be less than 5.5%, preferably less than 5%.

[0097] The first optical filter 100 can intentionally suppress the reflectance in the visible light region within a wide range of incident angles. Therefore, when the first optical filter 100 is applied to a solid-state imaging element, a clear image can be obtained.

[0098] (Near-infrared cut filter according to another embodiment of the present invention)

[0099] Next, refer to Figure 2 , describing another embodiment of the present invention.

[0100] Figure 2A cross section of a near-infrared cut filter (hereinafter referred to as a “second optical filter”) according to another embodiment of the present invention is schematically shown.

[0101] like Figure 2 As shown, the second optical filter 200 includes: a transparent substrate 210 having a first surface 212 ; a first matching film 240 ; an optical multilayer film 220 ; and a second matching film 260 .

[0102] The first matching film 240 is disposed on the first surface 212 of the transparent substrate 210 , and the optical multilayer film 220 is disposed on the first matching film 240 . Furthermore, the second matching film 260 is disposed on the outermost side of the first surface 212 .

[0103] Here, similarly to the first optical filter 100, the second optical filter 200 also has the following features:

[0104] In the wavelength range of 480 nm to 680 nm, the maximum value ΔR1 of the absolute value of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%.

[0105] In the wavelength range of 450 nm to 650 nm, the maximum value ΔR2 of the absolute value of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%.

[0106] The second optical filter 200 can intentionally suppress the reflectance in the visible light region within a wide range of incident angles. Therefore, when the second optical filter 200 is applied to a solid-state imaging element, a clear image can be obtained.

[0107] (Near-infrared cut filter according to another embodiment of the present invention)

[0108] Next, refer to Figure 3 , describing another embodiment of the present invention.

[0109] Figure 3 A cross section of a near-infrared cut filter (hereinafter referred to as a “third optical filter”) according to still another embodiment of the present invention is schematically shown.

[0110] like Figure 3 As shown, the third optical filter 300 includes: a transparent substrate 310 having a first surface 312 ; a first matching film 340 ; an optical multilayer film 320 ; a third matching film 350 ; and a second matching film 360 .

[0111] The first matching film 340 is provided on the first surface 312 of the transparent substrate 310. The optical multilayer film 320 is provided on the first matching film 340, and the third matching film 350 is disposed on the optical multilayer film 320. In addition, the second matching film 360 is provided on the outermost side of the first surface 312.

[0112] Here, like the first optical filter 100 and the second optical filter 200, the third optical filter 300 also has the following features:

[0113] In the wavelength range of 480 nm to 680 nm, the maximum value ΔR1 of the absolute value of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%.

[0114] In the wavelength range of 450 nm to 650 nm, the maximum value ΔR2 of the absolute value of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%.

[0115] The third optical filter 300 can intentionally suppress the reflectance in the visible light region within a wide range of incident angles. Therefore, when the third optical filter 300 is applied to a solid-state imaging element, a clear image can be obtained.

[0116] (Constituent components)

[0117] Next, each member constituting the near-infrared cut filter according to one embodiment of the present invention will be described in more detail.

[0118] It should be noted that, here, as an example, the third optical filter 300 is taken as an example to explain its constituent components. Figure 3 Reference numerals shown.

[0119] (Transparent substrate 310)

[0120] The transparent substrate 310 may be made of any material as long as it is transparent (high transmittance) to visible light. For example, the transparent substrate 310 may be made of glass (white glass, near-infrared absorbing glass, etc.) or resin.

[0121] (Optical multilayer film 320)

[0122] The optical multilayer film 320 has a repeated structure of a “high refractive index layer” and a “low refractive index layer” and has a function of reflecting near infrared rays (wavelength 750 nm to 900 nm).

[0123] In the present application, a “high refractive index layer” refers to a layer having a refractive index of 2.0 or higher at a wavelength of 500 nm, and a “low refractive index layer” refers to a layer having a refractive index of 1.6 or lower at a wavelength of 500 nm.

[0124] Examples of high-refractive-index layers include titanium oxide, tantalum oxide, and niobium oxide. Examples of low-refractive-index layers include silicon oxide and magnesium fluoride. For example, the refractive index of titanium oxide at a wavelength of 500 nm is generally in the range of 2.3 to 2.8, although it is affected by the crystalline state. The refractive index of silicon oxide is generally in the range of 1.4 to 1.5.

[0125] The number of layers of the optical multilayer film 320 is not particularly limited, and is, for example, in the range of 4 to 100. The number of layers is preferably in the range of 6 to 24.

[0126] In addition, half of the number of layers of the multilayer film (if there is a decimal, the decimal point is discarded) is also referred to as the "repetition number (n)".

[0127] The repetition number n of the optical multilayer film 320 is in the range of 2 to 50, and preferably in the range of 3 to 13.

[0128] The total thickness (physical film thickness) of the optical multilayer film 320 is, for example, in the range of 200 nm to 10 μm, or preferably in the range of 1 μm to 6 μm.

[0129] The optical multilayer film 320 may also have a function of reflecting near-ultraviolet rays and infrared rays (wavelength 900 nm to 1200 nm). In this case, the third optical filter 300 can shield near-ultraviolet rays and infrared rays.

[0130] (First Matching Film 340)

[0131] As described above, the first matching film 340 has the function of suppressing reflection of visible light.

[0132] The first matching film 340 may have a structure in which “high refractive index layers” and “low refractive index layers” are alternately stacked. As for the “high refractive index layers” and “low refractive index layers”, reference may be made to the above description.

[0133] When the first matching film 340 has a structure in which high refractive index layers and low refractive index layers are alternately stacked, the QWOT (Quarter-wave Optical Thickness) of the high refractive index layer at a wavelength of 550 nm is set to Q H , the QWOT of the low refractive index layer at a wavelength of 550nm is set to Q L When , the first matching film 340 may also have the following structures in order from the transparent substrate 310 side:

[0134] (H1Q H , L1Q L , H2Q H , L2QL ,……,H n Q H , L n Q L ) (1) (here, n is a natural number greater than 1). In addition, each coefficient can also satisfy the following formula:

[0135] 1.7≤W≤2.5 (2)

[0136] Here,

[0137] W=(H1+H2+…+H n ) / (L1+L2+…+L n ) (3) formula.

[0138] Q in formula (1) H and Q L Previous H1…H n and L1…L n The coefficients of H and Hw represent how many times the physical thickness of each layer is QWOT. n Q H and L n Q L etc. represent the optical film thickness of each layer.

[0139] The number of layers of the first matching film 340 is not particularly limited, but is preferably in the range of 2 to 20 layers. If the number of layers exceeds 20, film formation takes time, increasing the manufacturing cost of the third optical filter 300. The number of layers of the first matching film 340 is more preferably in the range of 6 to 16 layers, and even more preferably 12 layers or less.

[0140] (Second Matching Film 360)

[0141] The second matching film 360 , like the first matching film 340 , has a function of suppressing reflection of visible light.

[0142] The second matching film 360 preferably has a two-layer structure of a high refractive index layer and a low refractive index layer (ie, the number of repetitions n = 1). Note that the "high refractive index layer" and the "low refractive index layer" can refer to the above description.

[0143] In this case, the QWOT of the high refractive index layer at a wavelength of 550 nm is Q A , the QWOT of the low refractive index layer at a wavelength of 550nm is set to Q B When , the second matching film 360 has the following structure from the transparent substrate side:

[0144] (XQ A , YQ B ) (4)

[0145] Here, X>Y is preferred.

[0146] (Third Matching Film 350)

[0147] The third matching film 350 , like the first matching film 340 and the second matching film 360 , has a function of suppressing reflection of visible light.

[0148] The third matching film 350 may also have a structure of alternately stacked “high refractive index layers” and “low refractive index layers.” As for the “high refractive index layers” and “low refractive index layers,” reference may be made to the above description.

[0149] In particular, the third matching film 350 may be composed of the same number of layers as the first matching film 340. Furthermore, the third matching film 350 may be configured to satisfy the aforementioned equations (1) to (3).

[0150] For example, the third matching film 350 may be composed of 6 to 16 layers. In this case, the number of repetitions n is 3 to 8.

[0151] The third matching film 350 is not an essential structure, but the provision of the third matching film 350 can further suppress the reflection of visible light.

[0152] It should be noted that in Figure 3 In the example shown, the third matching film 350 is disposed on the optical multilayer film 320 disposed on the first matching film 340. However, the third matching film 350 may be disposed between the transparent substrate 310 and the optical multilayer film 320, and the first matching film 340 may be disposed on the optical multilayer film 320.

[0153] Above, each component included in the near infrared cut filter of one embodiment of the present invention has been described with the third optical filter 300 as an example. However, the above description can also be applied to the first optical filter 100 and the second optical filter 200, which is self-evident to those skilled in the art.

[0154] [Example]

[0155] Next, examples of the present invention will be described. Note that in the following description, Examples 1 to 4 are examples, and Examples 11 to 14 are comparative examples.

[0156] The optical characteristics of the near-infrared cut filters having the structures shown in the following examples were evaluated. The optical characteristics were evaluated using commercially available optical simulation software (TFCalc from Software SPectra, Inc.).

[0157] In the following evaluation, the reflectance of the near infrared cut filter represents regular reflectance obtained when light is incident from the first surface side of the transparent substrate (ie, the side provided with various films) at a predetermined angle relative to the normal.

[0158] The incident angles of light relative to the normal are 5° and 40°. Hereinafter, these incident directions are referred to as "5° incident" and "40° incident," respectively.

[0159] (Example 1)

[0160] The near infrared cut filter of Example 1 has Figure 1 The structure shown.

[0161] Glass (D263; manufactured by Schott) was used as the transparent substrate. In addition, the same glass was used in other examples.

[0162] The optical multilayer film has a structure of repeated low-refractive-index layers (SiO2 layers) and high-refractive-index layers (TiO2 layers). The number of layers is 17. Furthermore, the first matching film has a structure of repeated TiO2 and SiO2 layers, with 6 layers. Furthermore, the second matching film has a two-layer structure of TiO2 and SiO2 layers.

[0163] Table 1 below summarizes the layer structures of the optical multilayer film, the first matching film, and the second matching film used in Example 1.

[0164]

Table 1

[0165]

[0166] In the first matching film, the value of W represented by the aforementioned formula (3), that is, the value of (H1+H2+H3) / (L1+L2+L3), is 2.20.

[0167] In addition, in the second matching film, the QWOT (Q A )=1.898, QWOT(Q B ) is 0.887. When the second matching film is represented by the aforementioned formula (4), X / Y=2.14.

[0168] In Table 1, the layers are listed in order of proximity to the transparent substrate, and thus the layers are arranged on the transparent substrate from the top to the bottom in Table 1. This description also applies to Tables 2 to 8 below.

[0169] (Example 2)

[0170] The near infrared cut filter of Example 2 has Figure 1 The structure shown.

[0171] Glass is used as the transparent substrate.

[0172] The optical multilayer film has a structure of 18 layers of repeated TiO2 and SiO2 layers. Furthermore, the first matching film has a structure of 6 layers of repeated TiO2 and SiO2 layers. Furthermore, the second matching film has a double-layer structure of TiO2 and SiO2 layers.

[0173] Table 2 below summarizes the layer structures of the optical multilayer film, the first matching film, and the second matching film used in Example 2.

[0174]

Table 2

[0175]

[0176] In the first matching film, the value of W represented by the aforementioned formula (3), that is, the value of (H1+H2+H3) / (L1+L2+L3), is 1.71.

[0177] In addition, in the second matching film, the QWOT (Q A )=2.000, QWOT(Q B ) is 0.900. When the second matching film is represented by the aforementioned formula (4), X / Y=2.22.

[0178] (Example 3)

[0179] The near infrared cut filter of Example 3 has Figure 2 The structure shown.

[0180] Glass is used as the transparent substrate.

[0181] The first matching film has a structure of six repeated TiO2 and SiO2 layers. Furthermore, the optical multilayer film has a structure of 17 repeated SiO2 and TiO2 layers. Furthermore, the second matching film has a two-layer structure of TiO2 and SiO2 layers.

[0182] Table 3 below summarizes the layer structures of the first matching film, the optical multilayer film, and the second matching film used in Example 3.

[0183]

Table 3

[0184]

[0185] In the first matching film, the value of W represented by the aforementioned formula (3), that is, the value of (H1+H2+H3) / (L1+L2+L3), is 2.09.

[0186] In addition, in the second matching film, the QWOT (Q A )=1.587, QWOT(Q B ) is 0.884. When the second matching film is represented by the aforementioned formula (4), X / Y=1.80.

[0187] (Example 4)

[0188] The near infrared cut filter of Example 4 has Figure 3 The structure shown.

[0189] Glass is used as the transparent substrate.

[0190] The first matching film has a six-layer structure consisting of a repeated SiO2 layer and a TiO2 layer. Furthermore, the optical multilayer film has a six-layer structure consisting of a repeated SiO2 layer and a TiO2 layer. Furthermore, the third matching film has a six-layer structure consisting of a repeated TiO2 layer and a SiO2 layer. Furthermore, the second matching film has a two-layer structure consisting of a TiO2 layer and a SiO2 layer.

[0191] Table 4 below summarizes the layer structures of the first matching film, the optical multilayer film, the third matching film, and the second matching film used in Example 4.

[0192]

Table 4

[0193]

[0194] In the first matching film, the value of W represented by the aforementioned formula (3), that is, the value of (H1+H2+H3) / (L1+L2+L3), is 2.15.

[0195] In addition, in the second matching film, the QWOT (Q A )=1.983, QWOT(Q B ) is 0.921. When the second matching film is represented by the aforementioned formula (4), X / Y=2.15.

[0196] (Example 11)

[0197] The near-infrared cut filter in Example 11 has a structure having only an optical multilayer film on a transparent substrate. The optical multilayer film has a structure of repeated TiO2 layers and SiO2 layers, and the number of layers is 20.

[0198] Table 5 below shows the layer structure of the optical multilayer film used in Example 11.

[0199]

Table 5

[0200]

[0201] (Example 12)

[0202] The near-infrared cut filter in Example 12 has a structure having only an optical multilayer film on a transparent substrate. The optical multilayer film has a structure of repeated SiO2 layers and TiO2 layers, and the number of layers is 21.

[0203] Table 6 below shows the layer structure of the optical multilayer film used in Example 12.

[0204]

Table 6

[0205]

[0206] (Example 13)

[0207] The near-infrared cut filter in Example 13 has a structure in which an optical multilayer film and a first matching film are sequentially arranged on a transparent substrate.

[0208] The optical multilayer film has a structure of repeated SiO2 layers and TiO2 layers, with a number of layers set to 17. The first matching film has a structure of repeated TiO2 layers and SiO2 layers, with a number of layers set to 6.

[0209] Table 7 below summarizes the layer structures of the optical multilayer film and the first matching film used in Example 13.

[0210]

Table 7

[0211]

[0212] (Example 14)

[0213] The near infrared cut filter in Example 14 has Figure 1 The structure shown.

[0214] Glass is used as the transparent substrate.

[0215] The optical multilayer film has a structure of repeated SiO2 and TiO2 layers, with 17 layers. Furthermore, the first matching film has a structure of repeated TiO2 and SiO2 layers, with 6 layers. Furthermore, the second matching film has a double-layer structure of TiO2 and SiO2 layers.

[0216] Table 8 below summarizes the layer structures of the optical multilayer film, the first matching film, and the second matching film used in Example 14.

[0217]

Table 8

[0218]

[0219] (Evaluation Results of Optical Characteristics)

[0220] (Near infrared cut filter in Example 1)

[0221] Figures 4 to 6 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 1 are shown.

[0222] exist Figure 4 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 4 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0223] according to Figure 4 As a result, it was found that the near infrared cut filter in Example 1 has a transmission band in the visible light region (wavelength of about 450 nm to about 650 nm) and a reflection band in the near infrared region.

[0224] It should be noted that the wavelength range of the reflection band at 5° incidence is approximately 750 nm to 1000 nm, whereas the wavelength range of the reflection band at 40° incidence is approximately 700 nm to 900 nm. In other words, the wavelength range of the reflection band at 40° incidence is shifted toward the lower wavelength side compared to the wavelength range of the reflection band at 5° incidence.

[0225] However, it can be seen that in the case of either the first reflectivity R1 or the second reflectivity R2 , reflection can be sufficiently suppressed in the transmission band.

[0226] exist Figure 5 In Figure 4 The change in the first reflectance R1 in the wavelength range of 480 nm to 680 nm in the trace shown is shown in an enlarged manner.

[0227] It should be noted that Figure 5 The straight line y1 in is an approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm, and is expressed by the following formula:

[0228] y1=0.0353λ-16.087 (5)

[0229] Here, λ is the wavelength (the same applies hereinafter).

[0230] In addition, Figure 6 In Figure 4 The change in the second reflectance R2 in the wavelength range of 450 nm to 650 nm in the trace shown is shown in an enlarged manner.

[0231] Figure 6 The straight line y2 is an approximate straight line of the second reflectivity R2 in the wavelength range of 450nm to 650nm, and is expressed by the following formula:

[0232] y2=0.0532λ-24.315 (6)

[0233] From the above results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 2.35%.

[0234] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 5.38%.

[0235] (Near infrared cut filter in Example 2)

[0236] Figures 7 to 9 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 2 are shown.

[0237] exist Figure 7 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 7 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0238] according to Figure 7 As a result, it was found that the near infrared cut filter of Example 2 has a transmission band in the visible light region (wavelength of about 450 nm to about 650 nm) and a reflection band in the near infrared region.

[0239] Furthermore, in the transmission band, it can be seen that reflection can be sufficiently suppressed in both the first reflectance R1 and the second reflectance R2.

[0240] exist Figure 8 In Figure 7 The change in the first reflectance R1 in the wavelength range of 480 nm to 680 nm in the trace shown is shown in an enlarged manner.

[0241] Figure 8 The straight line y1 in is an approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm, and is expressed by the following formula:

[0242] y1=-0.0046λ+4.6073 (7)

[0243] In addition, Figure 9 In Figure 7The change in the second reflectance R2 in the wavelength range of 450 nm to 650 nm in the trace shown is shown in an enlarged manner.

[0244] Figure 9 The straight line y2 in the figure is an approximate straight line of the second reflectivity R2 in the wavelength range of 450 nm to 650 nm, and is expressed by the following formula:

[0245] y2=0.008λ-2.0209 (8)

[0246] From the above results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 3.25%.

[0247] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 3.98%.

[0248] (Near infrared cut filter in Example 3)

[0249] Figure 10 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 3 are shown.

[0250] exist Figure 10 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 10 , the results of the first reflectance R1, which is a regular reflectance obtained at 5° incidence, and the second reflectance R2, which is a regular reflectance obtained at 40° incidence, are shown together.

[0251] according to Figure 10 As a result, it can be seen that the near-infrared cut filter in Example 3 has a transmission band in the visible light region (wavelength of about 450 nm to about 650 nm) and a reflection band in the near-infrared region.

[0252] Furthermore, it can be seen that, in the transmission band, reflection can be sufficiently suppressed in both the first reflectance R1 and the second reflectance R2.

[0253] From the obtained results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength was obtained, ΔR1 = 1.27%.

[0254] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 4.41%.

[0255] (Near infrared cut filter in Example 4)

[0256] Figures 11 to 13The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 4 are shown.

[0257] exist Figure 11 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 11 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0258] according to Figure 11 As a result, it was found that the near infrared cut filter of Example 4 has a transmission band in the visible light region (wavelength of about 450 nm to about 650 nm) and a reflection band in the near infrared region.

[0259] Furthermore, it can be seen that, in the transmission band, reflection can be sufficiently suppressed in both the first reflectance R1 and the second reflectance R2.

[0260] exist Figure 12 In Figure 11 The change in the first reflectance R1 in the wavelength range of 480 nm to 680 nm in the trace shown is shown in an enlarged manner.

[0261] Figure 12 The straight line y1 in is an approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm, and is expressed by the following formula:

[0262] y1=0.0026λ-0.8325 (9)

[0263] In addition, Figure 13 In Figure 11 The change in the second reflectance R2 in the wavelength range of 450 nm to 650 nm in the trace shown is shown in an enlarged manner.

[0264] Figure 13 The straight line y2 in the figure is an approximate straight line of the second reflectivity R2 in the wavelength range of 450 nm to 650 nm, and is expressed by the following formula:

[0265] y2=0.015λ-6.6515 (10)

[0266] From the above results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 1.03%.

[0267] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 4.98%.

[0268] (Near infrared cut filter in Example 11)

[0269] Figures 14 to 16 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 11 are shown.

[0270] exist Figure 14 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 14 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0271] according to Figure 14 As a result, in the case of the near-infrared cut filter of Example 11, a decrease in reflectivity was observed in the visible light region at both 5° and 40° incidence. However, it can be seen that the values of the first reflectivity R1 and the second reflectivity R2 are not significantly suppressed in this region.

[0272] exist Figure 15 In Figure 14 The change in the first reflectance R1 in the wavelength range of 480 nm to 680 nm in the trace shown is shown in an enlarged manner.

[0273] Figure 15 The straight line y1 in is an approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm, and is expressed by the following formula:

[0274] y1=0.0735λ-27.775 (11)

[0275] In addition, Figure 16 In Figure 14 The change in the second reflectance R2 in the wavelength range of 450 nm to 650 nm in the trace shown is shown in an enlarged manner.

[0276] Figure 16 The straight line y2 in the figure is an approximate straight line of the second reflectivity R2 in the wavelength range of 450 nm to 650 nm, and is expressed by the following formula:

[0277] y2=0.0747λ-27.467 (12)

[0278] From the above results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 17.56%.

[0279] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 12.93%.

[0280] (Near infrared cut filter in Example 12)

[0281] Figures 17 to 19 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 12 are shown.

[0282] exist Figure 17 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 17 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0283] according to Figure 17 As a result, in the case of the near-infrared cut filter of Example 12, a decrease in reflectivity was observed in the visible light region for both the first reflectivity R1 and the second reflectivity R2. However, it can be seen that the values of the first reflectivity R1 and the second reflectivity R2 are not significantly suppressed in this region.

[0284] exist Figure 18 In Figure 17 The change in the first reflectance R1 in the wavelength range of 480 nm to 680 nm in the trace shown is shown in an enlarged manner.

[0285] Figure 18 The straight line y1 in is an approximate straight line of the first reflectivity R1 within the wavelength range of 480 nm to 680 nm, and is expressed by the following formula:

[0286] y1=0.0435λ-20.496 (13)

[0287] In addition, Figure 19 In Figure 17 The change in the second reflectance R2 in the wavelength range of 450 nm to 650 nm in the trace shown is shown in an enlarged manner.

[0288] Figure 19 The straight line y2 in the figure is an approximate straight line of the second reflectivity R2 in the wavelength range of 450 nm to 650 nm, and is expressed by the following formula:

[0289] y2=0.044λ-19.138 (14)

[0290] From the above results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 6.75%.

[0291] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 5.35%.

[0292] (Near infrared cut filter in Example 13)

[0293] Figure 20 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 13 are shown.

[0294] exist Figure 20 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 20 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0295] according to Figure 20 As a result, in the case of the near-infrared cut filter in Example 13, a decrease in reflectivity was observed in the visible light region for both the first reflectivity R1 and the second reflectivity R2. However, it can be seen that the values of the first reflectivity R1 and the second reflectivity R2 are not significantly suppressed in this region.

[0296] From the obtained results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 10.10%.

[0297] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 10.30%.

[0298] (Near infrared cut filter in Example 14)

[0299] Figure 21 The evaluation results of the optical characteristics obtained in the near-infrared cut filter of Example 14 are shown.

[0300] exist Figure 21 In the figure, the horizontal axis is wavelength and the vertical axis is reflectivity. Figure 21 , the results of the first reflectivity R1, a regular reflectivity obtained at 5° incidence, and the second reflectivity R2, a regular reflectivity obtained at 40° incidence, are shown together.

[0301] according to Figure 21 As a result, in the case of the near-infrared cut filter of Example 14, a decrease in reflectivity was observed in the visible light region for both the first reflectivity R1 and the second reflectivity R2. However, it can be seen that the values of the first reflectivity R1 and the second reflectivity R2 are not significantly suppressed in this region.

[0302] From the obtained results, when the maximum value ΔR1 of the absolute value of the difference between the first reflectance R1 and the value of the approximate straight line y1 at the same wavelength is obtained, ΔR1 = 10.30%.

[0303] Furthermore, when the maximum value ΔR2 of the absolute value of the difference between the second reflectance R2 and the value of the approximate straight line y2 at the same wavelength is obtained, ΔR2 = 14.77%.

[0304] Table 9 below shows the values of ΔR1 and ΔR2 obtained in the near-infrared cut filter of each example.

[0305]

Table 9

[0306]

[0307] Thus, in the near-infrared cut filters of Examples 1 to 4 satisfying ΔR1<5% and ΔR2<6%, it was confirmed that the reflection of light in the transmission band can be intentionally suppressed regardless of the incident angle of light.

Claims

1. A near infrared cut filter, wherein: have: a transparent substrate having a first surface; an optical multilayer film disposed on the first surface side of the transparent substrate; a first matching film, disposed on the first surface side of the transparent substrate; a second matching film, disposed on the outermost side of the first surface; The optical multilayer film has a structure in which high-refractive index layers and low-refractive index layers are alternately stacked, and the optical multilayer film has a function of reflecting near-infrared rays. The first matching film and the second matching film have the function of suppressing the reflection of visible light. The first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film. In this near infrared cut filter, The regular reflectance of light incident from the second matching film side at an incident angle of 5° is defined as a first reflectance R1, and the regular reflectance of light incident from the second matching film side at an incident angle of 40° is defined as a second reflectance R2. When the approximate straight line of the first reflectance R1 in the wavelength range of 480nm to 680nm is y1 and the approximate straight line of the second reflectance R2 in the wavelength range of 450nm to 650nm is y2, In the wavelength range of 480 nm to 680 nm, the maximum absolute value ΔR1 of the difference between the first reflectivity R1 and the value of the approximate straight line y1 at the same wavelength is less than 5%. In the wavelength range of 450 nm to 650 nm, the maximum absolute value ΔR2 of the difference between the second reflectivity R2 and the value of the approximate straight line y2 at the same wavelength is less than 6%. The first matching film has an alternating stacking structure of high refractive index layers and low refractive index layers. When the optical thickness of a quarter wavelength of light is defined as QWOT and the QWOT of the high refractive index layer at a wavelength of 550 nm is defined as Q H , the QWOT of the low refractive index layer at a wavelength of 550nm is set to Q L hour, The first matching film has the following structure from the transparent substrate side: (H1Q H ,L1Q L ,H2Q H ,L2Q L ,……H n Q H ,L n Q L ) Here, n is a natural number greater than 1. The coefficients satisfy the following formula: <h2 style=";text-align:left;direction:ltr">1.7≤(H1+H2+…+H<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> ) / (L1+L2+…+L<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> )≤2.20, Here, Q H and Q L Previous H1…H n and L1…L n The coefficient indicates how many times the physical thickness of each layer is the QWOT. The high refractive index layer refers to a layer having a refractive index of 2.0 or greater at a wavelength of 500 nm, and the low refractive index layer refers to a layer having a refractive index of 1.6 or less at a wavelength of 500 nm.

2. The near infrared cut filter according to claim 1, wherein The first matching film is composed of six or more layers.

3. The near infrared cut filter according to claim 1 or 2, wherein The second matching film has a double-layer structure of a high refractive index layer and a low refractive index layer. The QWOT of the high refractive index layer at a wavelength of 550 nm is set to Q A , the QWOT of the low refractive index layer at a wavelength of 550nm is set to Q B hour, The second matching film has the following structure from the transparent substrate side: (XQ A ,YQ B ) Here, Q A and Q B The coefficients of X and Y above indicate how many times the physical film thickness of each layer is the QWOT, and X>Y.

4. The near infrared cut filter according to claim 1 or 2, wherein A third matching film is provided on the first surface side, the third matching film having a structure of alternating stacking of high refractive index layers and low refractive index layers. The optical multilayer film is disposed between the first matching film and the third matching film.

5. The near infrared cut filter according to claim 4, wherein The third matching film is composed of the same number of layers as the first matching film.

6. The near infrared cut filter according to claim 1 or 2, wherein The optical multilayer film has a transmission band in the visible light region.

7. The near infrared cut filter according to claim 6, wherein The optical multilayer film has a reflection band in the near-ultraviolet region.

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