Optical filter, solid-state imaging device and camera module

Abstract

To provide an optical filter that is superior in a shielding property of a light beam of a specific wavelength region desired to be shielded, and to provide a device using the optical filter.SOLUTION: An optical filter is provided, including a substrate having absorption in a specific wavelength region, the optical filter has: a first dielectric multi-layer film in one face of the substrate; and a second dielectric multi-layer film in other face thereof, wherein the total number of layers of the first dielectric multi-layer film and the second dielectric multi-layer film are equal to or less than 60 layers, and wherein the optical filter satisfies following conditions (A) to (C) in the specific wavelength region. (A) an average value of transmittance of the substrate is less than 90%, (B) an average value of reflectance of a non-polarized light beam incident at an angle of 5° from a vertical direction with respect to a face of the first dielectric multi-layer film is equal to or more than 80%, and (C) an average value of reflectance of the non-polarized light beam incident at the angle of 5° from the vertical direction with respect to a face of the second dielectric multi-layer film is equal to or more than 80%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an optical filter, a solid-state imaging device, and a camera module. [Background technology]

[0002] Optical filters are used in various devices that utilize light rays in specific wavelength ranges, and the optical filters usually transmit light rays in specific wavelength ranges and block light rays in specific wavelength ranges, which are determined depending on the application in which the optical filter is used.

[0003] Solid-state imaging devices such as video cameras, digital still cameras, camera-equipped mobile phones, and smartphones use CCD and CMOS image sensors, which are solid-state imaging elements for capturing color images. These solid-state imaging elements use sensors sensitive to near-infrared light in their light receiving sections, and therefore require luminosity correction. When performing such luminosity correction, for example, a near-infrared cut filter (e.g., the near-infrared cut filter described in Patent Document 1) is used as the optical filter, which transmits light rays in the visible light range and blocks light rays in a specific near-infrared range.

[0004] Furthermore, in recent years, for the purpose of improving security and safety, there has been a growing trend in mobile phones such as smartphones, in-vehicle terminals, etc. to simultaneously perform imaging using visible light and distance measurement, face recognition, etc. using light in other wavelength ranges (e.g., near-infrared to infrared light range).When performing such distance measurement, face recognition, etc., an optical filter that transmits light of a specific wavelength in the near-infrared to infrared light range and blocks light of other specific wavelength ranges (e.g., near-infrared transmitting filter (IRPF)) is used as the optical filter.

[0005] Furthermore, there are devices that utilize light rays of specific wavelengths in the visible light and near-infrared light regions, and in these devices, for example, an optical filter is used that transmits light rays of specific wavelength regions in the near-infrared light region and light rays of the visible light region and blocks light rays of other specific wavelength regions (e.g., a visible-near-infrared selective transmission filter (DBPF)). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-200113 Summary of the Invention [Problem to be solved by the invention]

[0007] In the optical filters described above, it is preferable that the transmittance of light in the specific wavelength range to be blocked is as low as possible (excellent blocking properties). However, while conventional optical filters have been able to lower the transmittance of light in the specific wavelength range to be blocked to a certain extent, further improvement in blocking properties has been desired.

[0008] The present invention has been made in view of the above, and an object of the present invention is to provide an optical filter that has excellent blocking properties for light rays in a specific wavelength range that is desired to be blocked, and a device that uses the optical filter. [Means for solving the problem]

[0009] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following configuration examples, and have thus completed the present invention. In the present invention, the expression "A to B" or the like that expresses a numerical range is synonymous with "A or more, B or less," and A and B are included in the numerical range. In addition, in the present invention, a wavelength of A to B nm represents characteristics at a wavelength resolution of 1 nm in a wavelength region of wavelengths of Am or more and wavelengths of B nm or less.

[0010] [1] An optical filter including a substrate having absorption in a specific wavelength region, the optical filter has a first dielectric multilayer film on one surface of the substrate and a second dielectric multilayer film on the other surface, the total number of layers of the first dielectric multilayer film and the second dielectric multilayer film being 60 or less, The following requirements (A) to (C) are satisfied in the specific wavelength region: Optical filter. (A) The average transmittance of the substrate is less than 90%. (B) The average reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more. (C) The average reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

[0011] [2] The substrate is consisting of only an absorption layer 1 having absorption in the specific wavelength region, or The absorption layer 1 has absorption in the specific wavelength region, and another layer 2. [1] The optical filter according to [1].

[0012] [3] The optical filter according to [1] or [2], wherein the average transmittance of the substrate in the specific wavelength region is 20% or more and less than 90%.

[0013] [4] The optical filter according to any one of [1] to [3], wherein the width of the specific wavelength region is 5 to 300 nm. [5] The optical filter according to any one of [1] to [4], wherein the specific wavelength region is in the wavelength range of 700 to 1200 nm.

[0014] [6] The optical filter according to any one of [1] to [5], wherein the first dielectric multilayer film has a region in the wavelength range of 700 to 1000 nm in which the average reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more. [7] The optical filter according to any one of [1] to [6], wherein the second dielectric multilayer film has a region in the wavelength range of 800 to 1100 nm in which the average reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

[0015] [8] The optical filter according to any one of [1] to [7], which has a region A in which the average value of transmittance in the specific wavelength region is 0.01% or less. [9] The optical filter according to any one of [1] to [8], which has a region B in which the average value of transmittance is 85% or more in the wavelength range of 400 to 630 nm.

[0016]

[10] A solid-state imaging device comprising the optical filter according to any one of [1] to [9].

[11] A camera module comprising the optical filter according to any one of [1] to [9]. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an optical filter that has excellent blocking properties for light rays in a specific wavelength range that is desired to be blocked, and a device that uses the optical filter.

[0018] Optical filters are required to have high transmittance for light in a specific wavelength range that is desired to be transmitted and low transmittance for light in a specific wavelength range that is desired to be blocked; in other words, they are required to have a high contrast between the high transmittance regions and the low transmittance regions (hereinafter also referred to as "high contrast"). For example, when the near-infrared cut filter does not have high contrast, the use of this near-infrared cut filter may result in a deterioration in image quality due to an image defect called a ghost that originates from light in the near-infrared light region.

[0019] One method for realizing the high contrast is to increase the number of layers in a dielectric multilayer film that is commonly used in optical filters such as near-infrared cut filters. Increasing the number of layers in the dielectric multilayer film in this way can improve the blocking ability in a specific wavelength range. However, increasing the number of layers in the dielectric multilayer film can increase stress on the optical filter, which can cause deformation of the optical filter and lead to problems such as deterioration of the appearance and optical properties of the filter.

[0020] Another method for improving the shielding properties for light in the specific wavelength range to be shielded is to use a base material that has excellent absorption of light in the specific wavelength range to be shielded, for example by adding a large amount of a dye that has absorption in the specific wavelength range to be shielded. However, when a large amount of dye is used in this way, it is not possible to maintain high transmittance of light in a specific wavelength range that is desired to be transmitted, and high contrast cannot be realized.

[0021] On the other hand, according to the present invention, an optical filter can be provided that has high contrast (particularly, high transmittance for light in the visible light region and low transmittance for light in the near-infrared to infrared region) while maintaining low stress on the optical filter due to the dielectric multilayer film. Furthermore, according to the present invention, by using the optical filter, it is possible to provide a solid-state imaging device and a camera module in which ghosts in the obtained images are suppressed. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram illustrating an example of an optical filter of the present invention. [Figure 2] 1 is a schematic diagram illustrating an example of an optical filter of the present invention. [Figure 3] FIG. 2 is a graph showing the spectral transmittance curve of the substrate obtained in Example 1. [Figure 4] FIG. 2 is a diagram showing the spectral reflectance curve of the first dielectric multilayer film obtained in Example 1. [Figure 5] FIG. 3 is a graph showing the spectral reflectance curve of the second dielectric multilayer film obtained in Example 1. [Figure 6]FIG. 2 is a diagram showing the spectral transmittance curve of the optical filter obtained in Example 1. [Figure 7] FIG. 7 is an enlarged view of the wavelength region of 700 to 1200 nm in FIG. [Figure 8] FIG. 7 is an enlarged view of the wavelength region of 700 to 1200 nm in FIG. [Figure 9] FIG. 1 is a graph showing the spectral transmittance curve of the substrate obtained in Example 2. [Figure 10] FIG. 1 is a diagram showing the spectral transmittance curve of the optical filter obtained in Example 2. [Figure 11] FIG. 11 is an enlarged view of the wavelength region of 700 to 1200 nm in FIG. [Figure 12] FIG. 11 is an enlarged view of the wavelength region of 700 to 1200 nm in FIG. [Figure 13] FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter obtained in Example 3. [Figure 14] FIG. 1 is a diagram showing the spectral transmittance curve of the optical filter obtained in Example 4. [Figure 15] FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter obtained in Example 5. [Figure 16] FIG. 1 is a diagram showing the spectral transmittance curve of the optical filter obtained in Comparative Example 1. [Figure 17] FIG. 17 is an enlarged view of the wavelength region of 700 to 1200 nm in FIG. [Figure 18] FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter obtained in Comparative Example 2. [Figure 19] FIG. 10 is a diagram showing the spectral transmittance curve of the optical filter obtained in Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0023] Optical Filter The optical filter according to the present invention (hereinafter also referred to as "the filter") includes a substrate having absorption in a specific wavelength region, the optical filter has a first dielectric multilayer film on one surface of the substrate and a second dielectric multilayer film on the other surface, the total number of layers of the first dielectric multilayer film and the second dielectric multilayer film being 60 or less, The following requirements (A) to (C) are satisfied in the specific wavelength region. (A) The average transmittance of the substrate is less than 90%. (B) The average reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more. (C) The average reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

[0024] By satisfying requirements (A) to (C), when light in a specific wavelength range enters the optical filter, it undergoes multiple reflections between the first dielectric multilayer film and the second dielectric multilayer film, and is then absorbed by the substrate, thereby effectively preventing the occurrence of ghosts.

[0025] Since the present filter satisfies the requirements (A) to (C) in the specific wavelength region, the specific wavelength region can also be called a blocking region. As described above, the wavelength range to be blocked varies depending on the type of the present filter (e.g., near-infrared cut filter, near-infrared transmission filter, visible light-near-infrared selective transmission filter), and therefore the specific wavelength range is appropriately selected depending on the type of the present filter.

[0026] Since the present filter is suitably used as a near-infrared cut filter, in this case, specific examples of the specific wavelength region are preferably in the wavelength range of 700 to 1200 nm, more preferably in the wavelength range of 800 to 1000 nm. By having the specific wavelength region fall within the above range, the specific region from near infrared to infrared, which is the main cause of ghosts, is blocked, thereby further improving image quality.

[0027] The width of the specific wavelength region is preferably 5 to 300 nm. By having the width of the specific wavelength region within the above range, the number of layers in the dielectric multilayer film can be further reduced, thereby reducing stress on the optical filter and further preventing deformation of the optical filter.

[0028] In the present invention, the term "specific wavelength range" refers to a wavelength range in which the transmittance of light incident perpendicularly to the surface of the optical filter does not continuously exceed 0.01%. Here, "continuous" refers to the relationship between the transmittance at a wavelength Am and the transmittance at A-1 nm or A+1 nm. Hereinafter, the transmittance of a substrate or an optical filter refers to the transmittance of light incident perpendicularly to the surface of the substrate or optical filter. Here, the surface of the substrate or optical filter refers to the surface with the largest area (main surface) of the substrate or optical filter.

[0029] When the present filter is used as a filter that cuts off part or all of the near-infrared light, the present filter desirably has a region A in which the average transmittance in a specific wavelength region is 0.01% or less, preferably 0.001% or less.

[0030] In the present invention, the average value (average transmittance) of the transmittance in a certain wavelength range (wavelengths A to B nm) is a value calculated by measuring the transmittance at each wavelength from A nm to B nm in 1 nm increments and dividing the sum of the transmittances by the number of measured transmittances (wavelength range, B-A+1).

[0031] When the present filter is used as a filter that transmits visible light, it is desirable that the present filter have a region B in which the average transmittance in the wavelength region of 400 to 630 nm is preferably 85% or more, more preferably 90% or more.

[0032] The thickness of the present filter is preferably 32 to 220 μm, and within this range it is useful for making solid-state imaging devices thinner. The thickness of the present filter is more preferably 32 to 160 μm, and even more preferably 42 to 120 μm.Within this range, the filter can be suitably used in a thin solid-state imaging device having a total thickness of 6.5 mm or less.

[0033] One embodiment of the present filter is a filter having the configuration shown in FIG. 1 or FIG. Although the embodiments of the present invention will be described with reference to the drawings as necessary, the drawings are provided merely for illustration purposes, and the present invention is not limited to these drawings in any way. Furthermore, the drawings are schematic, and the relationship between thickness and planar dimensions, thickness ratios, etc. may differ from the actual ones.

[0034] This filter, for example, has excellent ability to cut off light in the wavelength range you want to cut off and excellent ability to transmit light in the wavelength range you want to transmit, resulting in high contrast. Therefore, it is useful for correcting the visibility of solid-state imaging elements such as CCD and CMOS image sensors in camera modules. It is particularly useful in digital still cameras, smartphone cameras, mobile phone cameras, digital video cameras, wearable device cameras, PC cameras, surveillance cameras, automotive cameras, infrared cameras, televisions, car navigation systems, personal digital assistants, video game consoles, portable game consoles, fingerprint authentication systems, digital music players, various sensing systems, infrared communications, and the like. It is also useful as a heat-cutting filter attached to glass panels in automobiles, buildings, and the like.

[0035] <Base material> The substrate used in the present filter is a substrate that has absorption in the specific wavelength region and is not particularly limited as long as it satisfies the requirement (A). The substrate, although it depends on the type of the filter, is preferably a substrate that transmits light in the visible light range (e.g., wavelengths of 400 to 630 nm), specifically, the average transmittance in the visible light range is preferably 85% or more, more preferably 90% or more.

[0036] Furthermore, in order to more effectively prevent the occurrence of ghosts, the average transmittance of the substrate in the specific wavelength range is preferably 20% or more and less than 90%, more preferably 40% or more and less than 90%, and even more preferably 60% or more and less than 90%.

[0037] Examples of the material of the substrate include glass, tempered glass, special glass, and resin. The substrate may have two or more glass (including glass, tempered glass, and special glass) layers, two or more resin layers, or one or more glass layers and one or more resin layers. The substrate preferably includes a layer having a glass transition temperature of 140° C. or higher, and more preferably includes a layer made of resin (resin layer) because it is less likely to break.

[0038] Suitable examples of the substrate include substrate A consisting only of absorption layer 1 having absorption in a specific wavelength region, and substrate B comprising absorption layer 1 having absorption in the specific wavelength region and another layer 2. An example of the present filter comprising substrate A is a filter comprising a substrate (substrate A) 10, a first dielectric multilayer film 21, and a second dielectric multilayer film 22, as shown in Fig. 1. An example of the present filter comprising substrates A and B is a filter comprising absorption layer 1 (11), other layers 2 (12, 13), the first dielectric multilayer film 21, and the second dielectric multilayer film 22, as shown in Fig. 2. The substrate A may have two or more absorbent layers 1, and in this case, the two or more absorbent layers 1 may be the same or different layers. The substrate B may have two or more absorbent layers 1 and two or more other layers 2. In this case, the two or more absorbent layers 1 may be the same or different layers, and the two or more other layers 2 may be the same or different layers.

[0039] A specific example of the absorbing layer 1 is a layer containing a light absorber, and when the specific wavelength region is the near-infrared region, it preferably contains a near-infrared absorber. That is, it is preferable to use a light absorber that allows the substrate to satisfy requirement (A) in the specific wavelength region. The near-infrared absorbent preferably contains at least one selected from inorganic near-infrared absorbents such as cesium tungsten oxide and copper (II) oxide, near-infrared absorbents that utilize surface plasmons such as gold nanorods, organic near-infrared absorbents such as cyanine dyes and squarylium dyes, and metal complex near-infrared absorbents such as metal dithiol complexes and metal phthalocyanine complexes.

[0040] The other layer 2 is not particularly limited as long as it is a layer that does not have absorption in a specific wavelength region, and examples thereof include a glass layer that does not contain a light absorbent and is made of glass, tempered glass, special glass, etc.; a resin layer that does not contain a light absorbent; and a functional layer. Examples of the functions of the functional layer include electrical conductivity, antistatic effect, foreign matter adhesion prevention effect, scratch prevention effect, anti-fogging property, heat resistance improvement effect, gas barrier property, high elasticity, scratch removal effect, flatness, surface roughness, moisture absorption, and anti-aging effect.

[0041] The base material preferably has 1 to 5 layers. If the base material has six or more layers, there are concerns about the adhesion between the layers and an increase in manufacturing costs. The closer the refractive index of each layer is, the better, and the difference in refractive index between each layer is preferably 0.3 or less.

[0042] The total thickness of the base material is preferably 30 to 200 μm, and this range is useful for making the solid-state imaging device thinner. The total thickness of the substrate is more preferably 30 to 150 μm, and even more preferably 40 to 110 μm.Within this range, the substrate can be suitably used in a thin solid-state imaging device having a total thickness of 6.5 mm or less. If the total thickness of the substrate is less than 30 μm, there is a concern that the substrate may be prone to warping or cracking.

[0043] [Glass] Examples of the glass include silicate glass, borosilicate glass, phosphate glass, copper phosphate glass, fluorophosphate glass, and copper fluorophosphate glass. An example of the silicate glass is D263 manufactured by SCHOTT. Examples of the phosphate glass and the fluorophosphate glass include BS3, BS4, BS6, BS7, BS8, BS10, BS11, BS12, BS13, BS16, and BS17 manufactured by Matsunami Glass Industry Co., Ltd.

[0044] [Tempered glass] Examples of the tempered glass include physically tempered glass, tempered laminated glass, and chemically tempered glass. Among these, chemically tempered glass is preferred because it has a thin compression layer and can be processed to reduce the thickness of the substrate. Specific examples of chemically tempered glass include "Dragontrail" manufactured by AGC Inc. and "Gorilla Glass" manufactured by Corning.

[0045] [Special glass] Examples of the special glass include alumina glass, yttrium aluminate, and yttrium oxide. An example of the alumina glass is "HICERAM" manufactured by NGK INSULATORS, LTD. An example of the yttrium aluminate or yttrium oxide is "EXYRIA" manufactured by CoorsTek Corporation.

[0046] [resin] Examples of the resin include polyester resins, polyether resins, acrylic resins, polyolefin resins, polycycloolefin resins, norbornene resins, polycarbonate resins, enethiol resins, epoxy resins, polyamide resins, polyimide resins, polyurethane resins, and polystyrene resins. Of these, norbornene resins, polyimide resins, and polyether resins are preferred. The resins may be used alone or in combination of two or more.

[0047] The refractive index of the resin can be adjusted by adjusting the molecular structure of the raw material components. Specific examples of methods for adjusting the refractive index include imparting a specific structure to the main chain or side chain of the polymer of the raw material components. The structure imparted to the polymer is not particularly limited, and examples thereof include a norbornene skeleton and a fluorene skeleton. The refractive index of the resin at a wavelength of 500 nm is preferably 1.40 to 1.7.

[0048] The resin may be a commercially available product, such as "Ogusol EA-F5003" (acrylic resin, refractive index: 1.60) manufactured by Osaka Gas Chemicals Co., Ltd., "Polymethyl methacrylate" (refractive index: 1.49) manufactured by Tokyo Chemical Industry Co., Ltd., "Polyisobutyl methacrylate" (refractive index: 1.48) manufactured by Tokyo Chemical Industry Co., Ltd., or "BR50" (refractive index: 1.56) manufactured by Mitsubishi Chemical Corporation.

[0049] Commercially available polyester resins include, for example, "OKP4HT" (refractive index: 1.64), "OKP4" (refractive index: 1.61), "B-OKP2" (refractive index: 1.64), and "OKP-850" (refractive index: 1.65) manufactured by Osaka Gas Chemicals Co., Ltd., and "Bylon 103" (refractive index: 1.55) manufactured by Toyobo Co., Ltd. Commercially available polycarbonate resins include, for example, "LeXan ML9103" (refractive index: 1.59) and "xylex" manufactured by SABIC. Examples of commercially available norbornene-based resins include "7507" manufactured by Mitsubishi Gas Chemical Company, Inc., "EP5000" (refractive index: 1.63), and "SP3810" (refractive index: 1.63), "SP1516" (refractive index: 1.60), and "TS2020" (refractive index: 1.59) manufactured by Teijin Limited. Examples of commercially available norbornene-based resins include "ARTON" (refractive index: 1.52) manufactured by JSR Corporation and "ZEONEX" (refractive index: 1.53) manufactured by Zeon Corporation.

[0050] The polyether resin is preferably a polymer having at least one structural unit selected from the group consisting of structural units represented by the following formulas (1) and (2), and may also have a structural unit represented by the following formula (3) or (4).

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] In the formula (1), R 1 ~R 4 each independently represents a monovalent organic group having 1 to 12 carbon atoms. a to d each independently represent an integer of 0 to 4, preferably 0 or 1, and more preferably 0.

[0056] In the formula (2), R 1 ~R 4 and a to d each independently represent R in the formula (1). 1 ~R 4 and a to d, Y represents a single bond, -SO2- or -CO-, and R 7 and R 8 each independently represents a halogen atom, a monovalent organic group having 1 to 12 carbon atoms, or a nitro group, and m represents 0 or 1. However, when m is 0, R 7 is not a cyano group. g and h each independently represent an integer of 0 to 4, preferably 0.

[0057] In the formula (3), R5 and R 6 each independently represents a monovalent organic group having 1 to 12 carbon atoms, Z represents a single bond, -O-, -S-, -SO2-, -CO-, -CONH-, -COO- or a divalent organic group having 1 to 12 carbon atoms, and n represents 0 or 1. e and f each independently represent an integer of 0 to 4, preferably 0.

[0058] In the formula (4), R 7 , R 8 , Y, m, g, and h each independently represent R 7 , R 8 , Y, m, g, and h are synonymous with R 5 , R 6 , Z, n, e, and f each independently represent R 5 , R 6 , Z, n, e and f.

[0059] The substrate preferably has a resin layer as the absorbent layer 1 or another layer 2, preferably as the absorbent layer 1. The substrate having the resin layer can easily provide an optical filter that has high transmittance for light having a wavelength of 400 to 630 nm, high heat resistance, resistance to warping and breaking, and a low in-plane retardation R. Therefore, a solid-state imaging device including an optical filter having the resin layer can provide high image quality and can be easily manufactured.

[0060] When the resin layer has a thickness of 1 μm, the average transmittance at wavelengths of 430 to 630 nm is preferably 90% or more, in order to provide a solid-state imaging device with high sensitivity.

[0061] The glass transition temperature of the resin layer is preferably 140° C. or higher, since this allows the solid-state imaging device to be manufactured in a low-temperature reflow process.

[0062] The resin layer can be formed, for example, by melt molding or cast molding, and if necessary, the base material can be produced by a method in which, after molding, the base material is coated with at least one coating agent selected from an antireflection agent, a hard coating agent, an antistatic agent, and the like.

[0063] Melt molding The resin layer can be produced by melt-molding pellets obtained by melt-kneading a resin, preferably a resin and a near-infrared absorbent; by melt-molding a resin composition containing a resin, preferably a resin and a near-infrared absorbent; or by melt-molding pellets obtained by removing a solvent from a resin composition containing a resin and a solvent, preferably a resin, a near-infrared absorbent, and a solvent. Examples of melt-molding methods include injection molding, melt extrusion molding, and blow molding.

[0064] Cast molding The resin layer can also be produced by a method of casting a resin composition containing a resin and a solvent, preferably a resin, a near-infrared absorbent, and a solvent, onto a suitable support and then removing the solvent; a method of casting a resin composition containing at least one coating agent selected from antireflection agents, hard coating agents, antistatic agents, etc., a near-infrared absorbent, and a resin onto a suitable support; or a method of casting a curable composition containing at least one coating agent selected from antireflection agents, hard coating agents, antistatic agents, etc., a near-infrared absorbent, and a resin onto a suitable support and then curing and drying the resulting composition. The resin layer thus obtained may be used after being peeled off from the support, or a laminate of the support and the resin layer may be used as the substrate without being peeled off from the support.

[0065] Furthermore, a resin layer can be formed directly on an optical component by coating the resin composition on an optical component such as a glass plate, quartz, or plastic and then drying the solvent, or by coating the curable composition on the optical component and then curing and drying it.

[0066] The amount of residual solvent in the resin layer obtained by the above method should be as small as possible, and is usually 3% by mass or less, preferably 1% by mass or less, and more preferably 0.5% by mass or less, relative to 100% by mass of the resin layer. When the amount of residual solvent is within the above range, a substrate that is resistant to deformation and changes in properties and can easily exhibit the desired functions can be easily obtained. Furthermore, depending on the application in which the present filter is used, there is a concern that the electrical circuits around the filter may be corroded, so it is desirable that the amount of residual halogen-containing solvent in the resin layer be 50 ppm or less.

[0067] [Near infrared absorber] The near-infrared absorbing agent preferably has a maximum absorption wavelength in the range of 650 to 1200 nm. By using a near-infrared absorber having an absorption maximum wavelength within the above range, an optical filter having high contrast, in particular, high transmittance for light in the visible light region and low transmittance for light in the near-infrared to infrared region, can be easily obtained.

[0068] Examples of the near-infrared absorbent include cyanine dyes, phthalocyanine dyes, dithiol dyes, diimonium dyes, squarylium dyes, croconium dyes, copper phosphates, and polymethine dyes. The structure of these compounds is not particularly limited, and generally known compounds or commercially available compounds can be used as long as they do not impair the effects of the present invention. In addition, the near-infrared absorbent used may be one type or multiple types, as long as they do not impair the effects of the present invention.

[0069] The content of the near-infrared absorbing agent is preferably 0.01 to 10.0 parts by mass with respect to 100 parts by mass of the resin contained in the resin layer. When the content of the near-infrared absorbing agent is within the above range, a substrate having suitable optical properties can be easily obtained.

[0070] Cyanine dyes The cyanine dye is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include the cyanine dyes described in JP-A-2009-108267, JP-A-2010-72575, JP-A-2016-060774, etc.

[0071] Phthalocyanine dyes The phthalocyanine dye is not particularly limited as long as it does not impair the effects of the present invention. Examples of the phthalocyanine dye include compounds described in paragraphs

[0026] to

[0027] of JP-A Nos. 2005-220060, 2007-169343, and 2013-195480, and Table 1 of WO 2015 / 025779. When a phthalocyanine dye is used, it is preferable to use it in combination with at least one other near-infrared absorbing agent.

[0072] Dithiol dyes The dithiol dye is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include the dithiol dyes described in JP-A No. 2006-215395 and WO 2008 / 086931. Alternatively, for example, chlorides of dithiol dyes may be used as described in WO 1998 / 034988.

[0073] Squarylium dyes The squarylium dye is not particularly limited as long as it does not impair the effects of the present invention. Examples thereof include squarylium dyes represented by the following formula (4) and squarylium dyes described in JP-A-2014-074002, JP-A-2014-052431, etc., and may be synthesized by a commonly known method.

[0074] [ka]

[0075] Specific examples of Rsq1 to Rsq6 in the formula (4) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, and an n-octyl group; groups in which an alkyl group is partially substituted with a substituent, such as a 2-hydroxyethyl group, a 2-cyanoethyl group, a 3-hydroxypropyl group, a 3-cyanopropyl group, a methoxyethyl group, an ethoxyethyl group, and a butoxyethyl group; aryl groups or groups in which an aryl group is partially substituted with a substituent, such as a phenyl group, a fluorophenyl group, a chlorophenyl group, a tolyl group, a diethylaminophenyl group, and a naphthyl group; alkenyl groups such as a vinyl group, a propenyl group, a butenyl group, and a pentenyl group; and aralkyl groups or groups in which an aralkyl group is partially substituted with a substituent, such as a benzyl group, a p-fluorobenzyl group, a phenylpropyl group, and a naphthylethyl group. Any number of hydrogen groups contained in Rsq1 to Rsq6 may be substituted with a substituent L. Examples of the substituent L include a group containing fluorine, chlorine, bromine, an amino group (which may be alkylated), a cyano group, a nitro group, an alkyl group, a hydroxyl group, a thiol group, an alkyl ether group, an alkylthioether group, or an ester group.

[0076] In view of solubility in resins, Rsq1 to Rsq6 in formula (4) are preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, or any of these groups in which any number of hydrogen atoms have been substituted with a substituent L, and more preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, or any of these groups in which any number of hydrogen atoms have been substituted with a substituent L.

[0077] Diimonium dyes The diimonium dye is not particularly limited as long as it does not impair the effects of the present invention. Examples thereof include diimonium dyes represented by the following formula (5), and diimonium dyes described in Japanese Patent No. 4168031, Japanese Patent No. 4252961, WO 2004 / 048480, etc., and may be synthesized by a commonly known method.

[0078] [ka]

[0079] Rdi1 to Rdi12 each independently represent a hydrogen atom, a halogen atom, a sulfo group, a hydroxyl group, a cyano group, a nitro group, a carboxy group, a phosphate group, or -NR g R h Group, -SR i Group, -SO2R i Group, -OSO2R i group or the following L a ~L h R g and R h are each independently a hydrogen atom, -C(O)R i group or the following L a ~L e R i is the following L a ~L e represents one of the following: (L a ) an aliphatic hydrocarbon group having 1 to 12 carbon atoms (L b ) Halogen-substituted alkyl group having 1 to 12 carbon atoms (L c ) Alicyclic hydrocarbon group having 3 to 14 carbon atoms (L d ) Aromatic hydrocarbon group having 6 to 14 carbon atoms (L e ) Heterocyclic group having 3 to 14 carbon atoms (L f ) an alkoxy group having 1 to 12 carbon atoms (L g ) an acyl group having 1 to 12 carbon atoms which may have a substituent L; (L h) an alkoxycarbonyl group having 1 to 12 carbon atoms which may have a substituent L; the substituent L is at least one selected from the group consisting of an aliphatic hydrocarbon group having 1 to 12 carbon atoms, a halogen-substituted alkyl group having 1 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 14 carbon atoms, an aromatic hydrocarbon group having 6 to 14 carbon atoms, and a heterocyclic group having 3 to 14 carbon atoms; X represents the anion required to neutralize the charge.

[0080] The Rdi1 to Rdi8 are preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclohexyl group, a phenyl group, or a benzyl group, and more preferably an isopropyl group, a sec-butyl group, a tert-butyl group, or a benzyl group.

[0081] Rdi9 to Rdi12 are preferably a chlorine atom, a fluorine atom, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclohexyl group, a phenyl group, a hydroxyl group, an amino group, a dimethylamino group, a cyano group, a nitro group, a methoxy group, an ethoxy group, an n-propoxy group, an n-butoxy group, an acetylamino group, a propionylamino group, an N-methylacetylamino group, a trifluoromethanoylamino group, a pentafluoroethanoylamino group, a tert-butanoylamino group, a cyclohexynoylamino group, or a phenyl group. Rdi9 to Rdi12 are preferably 0 to 4, and more preferably 1 to 4. Rdi9 to Rdi12 are preferably 0 to 4. The number of Rdi9 to Rdi12 bonded to the same aromatic ring is not particularly limited as long as it is 0 to 4, but is preferably 0 or 1.

[0082] The X is an anion required to neutralize the charge; if the anion is divalent, one molecule is required, and if the anion is monovalent, two molecules are required. In the latter case, the two anions may be the same or different, but from a synthesis standpoint, they are preferably the same. X is not particularly limited as long as it is an anion, and examples thereof include the anions listed in Table 1 below.

[0083] [Table 1]

[0084] As X, if the acid has high acidity when converted into an acid, the anion of the diimonium dye tends to improve the heat resistance of the diimonium dye, and therefore (X-10), (X-16), (X-17), (X-21), (X-22), (X-24), and (X-28) in Table 1 are particularly preferred.

[0085] Polymethine pigments The polymethine dye is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include polymethine dyes described in JP 2021-134350 A, WO 2021 / 085372 A, etc.

[0086] Among the near-infrared absorbents, the compounds represented by formula (4), the compounds represented by formula (5), and polymethine dyes are preferred because of their high visible light transmittance, absorption characteristics in the wavelength range of 700 to 750 nm, and absorption characteristics in the wavelength range of 800 to 1100 nm.

[0087] [Near UV absorber] When it is desired to cut near-ultraviolet rays using the present filter, it is preferable to use a near-ultraviolet absorber in the substrate. By using a near-ultraviolet absorber in addition to the near-infrared absorber, an optical filter having small incidence angle dependency even in the near-ultraviolet wavelength region can be obtained. The near-ultraviolet absorbent used may be one kind or a plurality of kinds, as long as it does not impair the effects of the present invention.

[0088] The near-ultraviolet absorber is preferably at least one selected from the group consisting of azomethine compounds, indole compounds, benzotriazole compounds, triazine compounds, merophthalocyanine compounds, oxazole compounds, naphthalimide compounds, oxadiazole compounds, oxazine compounds, oxazolidine compounds, and anthracene compounds, and is preferably a compound having at least one absorption maximum in the wavelength range of 300 to 420 nm.

[0089] The near-ultraviolet absorber may be a commercially available product, and examples of such commercially available products include "A BS 407" manufactured by Exiton, "UV 381A", "UV 381B", "UV 382A", and "UV 386A" manufactured by QCRSolutions, "TINUVIN 326", "TINUVIN 460", and "TINUVIN 479" manufactured by BASF, and "BONA3911" manufactured by Orient Chemical Industries, Ltd.

[0090] The content of the near-ultraviolet absorber is usually 0.01 to 5.0 parts by mass, and preferably 0.05 to 2.0 parts by mass, relative to 100 parts by mass of the resin contained in the resin layer. When the content of the near-ultraviolet absorber is within the above range, a substrate having suitable optical properties can be easily obtained.

[0091] Azomethine compounds The azomethine compound is not particularly limited, but examples thereof include compounds represented by the following formula (6).

[0092] [ka]

[0093] In formula (6), R a1 ~R a5each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxy group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkoxycarbonyl group having 1 to 9 carbon atoms.

[0094] Indole compounds The indole compound is not particularly limited, but examples thereof include compounds represented by the following formula (7).

[0095] [ka]

[0096] In formula (7), R b1 ~R b5 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxy group, a cyano group, a phenyl group, an aralkyl group, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or an alkoxycarbonyl group having 1 to 9 carbon atoms.

[0097] Benzotriazole compounds The benzotriazole-based compound is not particularly limited, but examples thereof include compounds represented by the following formula (8).

[0098] [ka]

[0099] In formula (8), R c1 ~R c3 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, an aralkyl group, an alkyl group having 1 to 9 carbon atoms, an alkoxy group having 1 to 9 carbon atoms, or a group in which an alkyl group having 1 to 9 carbon atoms has been partially substituted with an alkoxycarbonyl group having 1 to 9 carbon atoms.

[0100] Triazine compounds The triazine-based compound is not particularly limited, but examples thereof include compounds represented by the following formula (9), (10) or (11).

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] In formulas (9) to (11), R d1 R independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an alkenyl group having 3 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkylaryl or arylalkyl group having 7 to 18 carbon atoms. However, these alkyl, cycloalkyl, alkenyl, aryl, alkylaryl, and arylalkyl groups may be substituted with a hydroxy group, a halogen atom, an alkyl group or an alkoxy group having 1 to 12 carbon atoms, and may contain an oxygen atom, a sulfur atom, a carbonyl group, an ester group, an amide group, or an imino group. d2 ~R d9 each independently represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an alkenyl group having 3 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkylaryl or arylalkyl group having 7 to 18 carbon atoms.

[0105] Merophthalocyanine compounds An example of the melophthalocyanine compound is "S0511" manufactured by Few Chemicals.

[0106] Oxazole compounds Examples of the oxazole-based compounds include "Uvitex OB" manufactured by BASF, "Hakkol RF-K" manufactured by Showa Chemical Industry Co., Ltd., and "Nikkafluor EFS" and "Nikkafluor SB-conc" manufactured by Nippon Chemical Industry Co., Ltd.

[0107] Naphthalimide compounds An example of the naphthalimide compound is "Lumogen Fviolet 570" manufactured by BASF.

[0108] [Other ingredients] The substrate may further contain additives such as antioxidants, ultraviolet absorbers, dispersants, flame retardants, plasticizers, heat stabilizers, light stabilizers, and metal complex compounds, within the range that does not impair the effects of the present invention. Furthermore, when the resin layer is formed by the above-mentioned cast molding, the production of the resin layer can be facilitated by adding a leveling agent or an antifoaming agent. These other components may each be used alone or in combination of two.

[0109] These other components may be mixed with the resin when forming the resin layer, or may be added when producing the resin. The amount added is selected appropriately depending on the desired properties, but is usually 0.01 to 5.0 parts by mass, and preferably 0.05 to 2.0 parts by mass, per 100 parts by mass of the resin.

[0110] Examples of the antioxidant include 2,6-di-tert-butyl-4-methylphenol, 2,2'-dioxy-3,3'-di-t-butyl-5,5'-dimethyldiphenylmethane, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0111] <Dielectric multilayer film> One of the features of this filter is that it has a first dielectric multilayer film on one side of a substrate and a second dielectric multilayer film on the other side, and the total number of layers in the first dielectric multilayer film and the second dielectric multilayer film is 60 or less. By limiting the total number of layers of the first dielectric multilayer film and the second dielectric multilayer film to 60 or less, stress due to the dielectric multilayer film can be reduced, and deformation of the filter can be prevented. To further prevent deformation of the filter, the total number of layers is preferably 54 or less, and more preferably 50 or less. The lower limit of the total number of layers is preferably 5, and more preferably 10. The term "one surface of the substrate" refers to one of the main surfaces of the substrate, that is, one of the surfaces of the substrate having the largest area. In this case, the other surface of the substrate having the largest area is the other surface.

[0112] In a specific wavelength range, the average reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more, preferably 90% or more, and more preferably 99% or more. Furthermore, in a specific wavelength range, the average value of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more, preferably 90% or more, and more preferably 99% or more.

[0113] In the present invention, the average value (average reflectance) of reflectance in a specific wavelength range (e.g., wavelengths A to B nm) is a value calculated by measuring the reflectance at each wavelength from A nm to B nm in 1 nm increments, and dividing the sum of the reflectances by the number of measured reflectances (wavelength range, B-A+1). It is extremely difficult to measure the reflectance of unpolarized light incident perpendicularly to the surface of a dielectric multilayer film, so in the present invention, the reflection characteristics of unpolarized light incident at an angle of 5° from the perpendicular to the surface of the dielectric multilayer film are measured.

[0114] "Unpolarized light" refers to light that has no polarization direction bias, and refers to a collection of waves in which the electric field is distributed more or less uniformly in all directions. The "average transmittance of unpolarized light" may be the average of the "average transmittance of S-polarized light" and the "average transmittance of P-polarized light." The "average reflectance of unpolarized light" may be the average of the "average reflectance of S-polarized light" and the "average reflectance of P-polarized light."

[0115] The first dielectric multilayer film is preferably a dielectric multilayer film in which the average value of the reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction falls within the above-mentioned range in the wavelength range of preferably 700 to 1000 nm, more preferably 800 to 950 nm. Furthermore, it is desirable that the second dielectric multilayer film be a dielectric multilayer film in which the average value of the reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction falls within the above-mentioned range, preferably in the wavelength range of 800 to 1100 nm, more preferably 800 to 1000 nm. When the wavelength range in which the average reflectance values ​​of the first dielectric multilayer film and the second dielectric multilayer film fall within the above range is within the above range, an optical filter that can block light from a wider range of the near-infrared to infrared region can be easily obtained.

[0116] The dielectric multilayer film may be a laminate in which high refractive index material layers and low refractive index material layers are alternately stacked. The high refractive index material layer can be made of a material having a refractive index of 1.7 or more, and a material having a refractive index in the range of 1.7 to 2.5 is usually selected. Examples of such materials include those containing titania, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide, or indium oxide as the main component, with small amounts (e.g., 0 to 10% by mass of the main component) of titanium oxide, tin oxide, and / or cerium oxide.

[0117] The low refractive index material layer can be made of a material with a refractive index of 1.6 or less, and a material with a refractive index in the range of 1.2 to 1.6 is usually selected. Examples of such materials include silica, alumina, lanthanum fluoride, magnesium fluoride, and sodium aluminum hexafluoride.

[0118] The method for laminating high-refractive index material layers and low-refractive index material layers is not particularly limited as long as a dielectric multilayer film is formed by laminating these material layers. For example, a dielectric multilayer film in which high-refractive index material layers and low-refractive index material layers are alternately laminated can be formed directly on the substrate by a CVD method, a vacuum deposition method, a sputtering method, an ion-assisted deposition method, an ion plating method, a radical-assisted sputtering method, or the like. Ion-assisted deposition, ion plating, and radical-assisted sputtering are preferred because they can produce high-quality multilayer films whose optical thicknesses are less susceptible to environmental changes. Ion-assisted deposition is even more preferred because it can reduce warping of the resulting optical filter.

[0119] Furthermore, if warping occurs in the substrate when the dielectric multilayer film is formed, in order to eliminate this, the surface of the substrate on which the dielectric multilayer film is formed may be irradiated with electromagnetic waves such as ultraviolet rays. In the case of irradiating with electromagnetic waves, irradiation may be performed during the formation of the dielectric multilayer film, or separately after the formation of the dielectric multilayer film.

[0120] The first and second dielectric multilayer films can be formed by, for example, designing them as in Design 1 and Design 2 shown in Table 2 below. In this case, the thickness and number of each layer can be optimized using optical thin film design software (Essential Macleod, manufactured by Thin Film Center) to match the wavelength-dependent characteristics of the refractive index of the substrate and the light absorption characteristics of the light absorber used so as to achieve anti-reflection effects in the visible range and selective transmission / reflection performance in the near-infrared range. Examples of input parameters (target values) to the software when performing optimization include the input parameters in Table 2 below.

[0121] [Table 2]

[0122] <Solid-state imaging device> The solid-state imaging device according to the present invention includes the filter. Here, the solid-state imaging device is a device equipped with a solid-state imaging element such as a CCD or CMOS image sensor. The solid-state imaging element is made of a photoelectric conversion element, such as a silicon photodiode or organic semiconductor, that converts light of a specific wavelength into an electric charge.

[0123] <Camera module> A camera module according to the present invention includes the filter. Here, the camera module may be a device that includes an image sensor, a focus adjustment mechanism, a phase detection mechanism, a distance measurement mechanism, etc., and outputs image and distance information as electrical signals. [Example]

[0124] The present invention will be described below with reference to examples, but the present invention is not limited to these examples in any way. The methods for measuring and evaluating various physical properties in the examples are as follows.

[0125] <Glass transition temperature> The glass transition temperatures of the resins used below were measured using a differential scanning calorimeter "DSC6200" manufactured by Hitachi High-Tech Science Corporation under conditions of a temperature rise rate of 20°C / min in a nitrogen gas flow.

[0126] <Transmittance> The transmittance was measured using a spectrophotometer "U-4100" manufactured by Hitachi High-Tech Corp. When measured perpendicular to the substrate or optical filter, the transmittance was measured using unpolarized light that was transmitted perpendicularly through the substrate or optical filter.

[0127] <Reflectance> The spectral reflectance was measured using a spectrophotometer "U-4100" manufactured by Hitachi High-Tech Corporation, by measuring the intensity of light reflected by the first dielectric multilayer film or the second dielectric multilayer film at an incident angle of 5° using the absolute reflectance measurement method.

[0128] <Contrast evaluation> For optical filters, the average transmittance in the wavelength range of 465 to 680 nm was taken as Tra.Vis, and the average transmittance in the wavelength range of 880 to 1010 nm was taken as Tra.IR, and the value of Tra.Vis / Tra.IR was calculated. The larger this value, the higher the contrast between the visible light range and a specific wavelength range (near-infrared range) different from the visible light range, and the better the image quality will be even in dark places.

[0129] <Ghost Evaluation> The resulting optical filter was placed between the lens and sensor used in an imaging device (Shikino High-Tech Corporation's "KBCR-M04VG") that uses a sensor with a photoelectric conversion element made from silicon photodiodes. In a dark room free from the influence of external light, ambient stray light was blocked, and imaging was performed using an LED light with maximum intensity between 850 nm and 970 nm as the light source. As a result of imaging, an image that appeared in a place different from the light source used for imaging was considered a ghost; if a ghost was observed, the ghost performance was deemed poor, and if no ghost was observed, the ghost performance was deemed good.

[0130] [Example 1] 100 parts by weight of "ARTON" norbornene resin (manufactured by JSR Corporation) (refractive index of light with a wavelength of 550 nm: 1.52, glass transition temperature: 160°C), 0.1 parts by weight of CIR-RL (manufactured by Nippon Carlit Co., Ltd.) as infrared absorber A, and 0.05 parts by weight of a phenolic antioxidant (manufactured by ADEKA Corporation, "ADK STAB AO-20") were dissolved in methylene chloride to obtain a solution with a solid content of 30% by weight. The resulting solution was then cast onto a smooth glass plate, dried at 50°C for 8 hours, further dried under reduced pressure at 100°C for 1 hour, and then peeled off from the glass plate to obtain a substrate with a thickness of 0.1 mm. The optical properties (transmittance) of the obtained substrate are shown in FIG.

[0131] An ion-assisted vacuum deposition apparatus was used to form a dielectric multilayer film (near-infrared reflective film) [a laminate consisting of alternating layers of silica (SiO2: refractive index of 1.46 for light with a wavelength of 550 nm) and titania (TiO2: refractive index of 2.48 for light with a wavelength of 550 nm)] on both sides of the obtained substrate at a deposition temperature of 120°C according to designs (1) and (2) shown in Table 3 below, thereby producing an optical filter with a thickness of 0.106 mm. Note that the thickness in Table 3 indicates the physical film thickness.

[0132] [Table 3]

[0133] The reflectance of the dielectric multilayer film (first dielectric multilayer film) obtained in design (1) was measured, and its optical characteristics are shown in Figure 4. The reflectance of the dielectric multilayer film (second dielectric multilayer film) obtained in design (2) was measured, and its optical characteristics are shown in Figure 5. The optical characteristics of the fabricated optical filter are shown in Figure 6. Figures 7 and 8 show enlarged views of the wavelength region of 700 to 1200 nm in Figure 6. The evaluation results of the optical filter obtained in Example 1 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Example 1 is suitable for solid-state imaging devices and camera modules.

[0134] [Example 2] A substrate having a thickness of 0.1 mm was obtained in the same manner as in Example 1, except that the content of infrared absorber A was changed to 0.01 parts by mass. The optical properties (transmittance) of the obtained substrate are shown in FIG.

[0135] First and second dielectric multilayer films were formed on both sides of the obtained substrate in the same manner as in Example 1, thereby producing an optical filter with a thickness of 0.106 mm. The optical characteristics of the fabricated optical filter are shown in Figure 10. Figures 11 and 12 show enlarged views of the wavelength region of 700 to 1200 nm in Figure 10. The evaluation results of the optical filter obtained in Example 2 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Example 2 is suitable for solid-state imaging devices and camera modules.

[0136] [Example 3] A substrate having a thickness of 0.1 mm was obtained in the same manner as in Example 1, except that 0.06 parts by mass of a compound represented by the following formula (12) was used as infrared absorber B instead of 0.1 parts by mass of infrared absorber A. The evaluation results of the obtained substrates are shown in Table 7.

[0137] [ka] [Ph: phenyl group]

[0138] An optical filter having a thickness of 0.105 mm was produced by forming dielectric multilayer films of design (3) and design (4) (first and second dielectric multilayer films, respectively) shown in Table 4 below on both sides of the obtained substrate.

[0139] [Table 4]

[0140] The optical characteristics of the fabricated optical filter are shown in FIG. The evaluation results of the optical filter obtained in Example 3 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Example 3 is suitable for solid-state imaging devices and camera modules.

[0141] [Example 4] A substrate having a thickness of 0.1 mm was obtained in the same manner as in Example 1, except that 0.04 parts by mass of a compound represented by the following formula (13) was used as infrared absorber C instead of 0.1 parts by mass of infrared absorber A. The evaluation results of the obtained substrates are shown in Table 7.

[0142] [ka]

[0143] An optical filter having a thickness of 0.105 mm was produced by forming dielectric multilayer films of designs (5) and (6) (first and second dielectric multilayer films, respectively) shown in Table 5 below on both sides of the obtained substrate.

[0144] [Table 5]

[0145] The optical characteristics of the fabricated optical filter are shown in FIG. The evaluation results of the optical filter obtained in Example 3 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Example 4 is suitable for solid-state imaging devices and camera modules.

[0146] [Example 5] Methylene chloride was added to and dissolved in 100 parts by mass of "ARTON," a norbornene-based resin manufactured by JSR Corporation, 0.3 parts by mass of the infrared absorber B, and 0.05 parts by mass of a phenol-based antioxidant ("ADEKA STAB AO-20," manufactured by ADEKA Corporation), to obtain a solution (A) with a solid content of 30% by mass. Similarly, 100 parts by mass of norbornene-based resin "ARTON" manufactured by JSR Corporation, 0.2 parts by mass of the infrared absorber C, and 0.05 parts by mass of a phenol-based antioxidant ("ADEKA STAB AO-20" manufactured by ADEKA Corporation) were dissolved in methylene chloride to obtain a solution (B) with a solid content of 30% by mass. Next, the obtained solution (A) was cast onto a smooth glass plate so that the thickness of the obtained film was 0.05 mm, dried at 50 ° C. for 8 hours, and further dried under reduced pressure at 100 ° C. for 1 hour. On the obtained film, solution (B) was further cast onto the obtained film so that the thickness of the obtained film was 0.05 mm, dried at 50 ° C. for 8 hours, and further dried under reduced pressure at 100 ° C. for 1 hour. Thereafter, by peeling from the glass plate, a substrate with a total thickness of 0.1 mm was obtained. The evaluation results of the obtained substrates are shown in Table 7.

[0147] First and second dielectric multilayer films were formed on both sides of the obtained substrate in the same manner as in Example 4, thereby producing an optical filter with a thickness of 0.105 mm. The optical characteristics of the fabricated optical filter are shown in FIG. The evaluation results of the optical filter obtained in Example 5 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Example 5 is suitable for solid-state imaging devices and camera modules.

[0148] [Comparative Example 1] A 0.1 mm thick transparent glass D263 (manufactured by SCHOTT) was used as the substrate, and first and second dielectric multilayer films were formed on both sides of the substrate in the same manner as in Example 1 to produce an optical filter with a thickness of 0.106 mm. The evaluation results of the substrates used are shown in Table 7, and the optical properties of the fabricated optical filter are shown in Fig. 16. Fig. 17 shows an enlarged view of the wavelength region of 700 to 1200 nm in Fig. 16. The evaluation results of the optical filter obtained in Comparative Example 1 are shown in Table 7. The optical filter obtained in Comparative Example 1 was unsuitable for solid-state imaging devices and camera modules.

[0149] Comparative Example 2 A substrate having a thickness of 0.1 mm was obtained in the same manner as in Example 1, except that 0.06 parts by mass of a compound represented by the following formula (14) was used as infrared absorber D instead of 0.1 parts by mass of infrared absorber A. The evaluation results of the obtained substrates are shown in Table 7.

[0150] [ka] [Me: methyl group, i-Pr: isopropyl group]

[0151] First and second dielectric multilayer films were formed on both sides of the obtained substrate in the same manner as in Example 4, thereby producing an optical filter with a thickness of 0.105 mm. The optical characteristics of the fabricated optical filter are shown in FIG. The evaluation results of the optical filter obtained in Comparative Example 2 are shown in Table 7. The results in Table 7 show that the optical filter obtained in Comparative Example 2 was unsuitable for solid-state imaging devices and camera modules.

[0152] Comparative Example 3 A substrate having a thickness of 0.1 mm was obtained in the same manner as in Example 1, except that 0.06 parts by mass of infrared absorber B was used instead of 0.1 parts by mass of infrared absorber A. The evaluation results of the obtained substrates are shown in Table 7.

[0153] An optical filter having a thickness of 0.107 mm was produced by forming dielectric multilayer films of designs (7) and (8) (first and second dielectric multilayer films, respectively) shown in Table 6 below on both sides of the obtained substrate.

[0154] [Table 6]

[0155] The optical characteristics of the fabricated optical filter are shown in FIG. The evaluation results of the optical filter obtained in Comparative Example 3 are shown in Table 7. The optical filter obtained in Comparative Example 3 was deformed due to the internal stress of the dielectric multilayer film, and was therefore unsuitable for assembly into a solid-state imaging device or a camera module.

[0156] [Table 7] [Industrial Applicability]

[0157] This filter is useful for correcting the visibility of solid-state imaging devices such as CCDs and CMOSs ​​in camera modules, and is particularly useful in digital still cameras, mobile phone cameras, smartphone cameras, digital video cameras, PC cameras, surveillance cameras, automotive cameras, televisions, car navigation systems, personal digital assistants, PCs, video games, portable game consoles, fingerprint authentication systems, iris authentication systems, face authentication systems, distance measurement sensors, distance measurement cameras, digital music players, etc.

[0158] In addition, this filter is also useful for improving the signal-to-noise contrast for sensing applications other than those for luminosity correction. For example, in vegetation sensing, signal-to-noise contrast is required in specific wavelength ranges, not just visible light, and in biological monitoring such as monitoring red blood cell concentration, signal-to-noise contrast is required in the red wavelength range. [Explanation of symbols]

[0159] 1: This filter 10: Base material 11: Absorption layer 1 12, 13: Other layers 2 21: First dielectric multilayer film 22: Second dielectric multilayer film

Claims

1. An optical filter including a substrate having absorption in a specific wavelength region, the optical filter has a first dielectric multilayer film on one surface of the substrate and a second dielectric multilayer film on the other surface, the total number of layers of the first dielectric multilayer film and the second dielectric multilayer film being 60 or less, The specific wavelength region is in a wavelength range of 789 to 1200 nm, and the width of the specific wavelength region is 146 to 300 nm, The following requirements (A) to (C) are satisfied in the specific wavelength region: Optical filter. (A) The average transmittance of the substrate is less than 90%. (B) The average reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more. (C) The average reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

2. The substrate is or consisting of only an absorption layer 1 having absorption in the specific wavelength region; The absorption layer 1 has absorption in the specific wavelength region, and another layer 2. The optical filter according to claim 1 .

3. 3. The optical filter according to claim 1, wherein the average transmittance of the substrate in the specific wavelength region is 20% or more and less than 90%.

4. The optical filter according to any one of claims 1 to 3, wherein the first dielectric multilayer film has a region in a wavelength range of 700 to 1000 nm, in which the average value of the reflectance of unpolarized light incident on the surface of the first dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

5. The optical filter according to any one of claims 1 to 4, wherein the second dielectric multilayer film has a region in a wavelength range of 800 to 1100 nm, in which the average value of the reflectance of unpolarized light incident on the surface of the second dielectric multilayer film at an angle of 5° from the perpendicular direction is 80% or more.

6. 6. The optical filter according to claim 1, which has a region A in which the average value of transmittance in the specific wavelength region is 0.01% or less.

7. 7. The optical filter according to claim 1, which has a region B in which the average transmittance is 85% or more in the wavelength range of 400 to 630 nm.

8. A solid-state imaging device comprising the optical filter according to any one of claims 1 to 7.

9. A camera module comprising the optical filter according to any one of claims 1 to 7.

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