Light-absorbing film and light-absorbing film manufacturing method

Abstract

To provide an optical filter including a frame and a light-absorbing film and, for an article including the frame to which the light-absorbing film is attached, capable of exhibiting favorable resistance to a variation, such as a temperature variation, in an environmental condition.SOLUTION: An optical filter 1 includes a frame 10 and a light-absorbing film 20. The frame 10 has a through hole 12. The light-absorbing film 20 is disposed to close the through hole 12 and includes a light-absorbing compound. An average Young's modulus of the light-absorbing film 20 measured by continuous stiffness measurement is 2.5 GPa or less.SELECTED DRAWING: Figure 1B

Description

Technical Field

[0001] The present invention relates to an optical filter, an imaging device, and a method for manufacturing an optical filter.

Background Art

[0002] In an imaging device using a solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), various optical filters are arranged in front of the solid-state imaging device in order to obtain an image having good color reproducibility. Generally, a solid-state imaging device has spectral sensitivity in a wide wavelength range from the ultraviolet region to the infrared region. On the other hand, human visual sensitivity exists only in the visible light region. For this reason, in order to make the spectral sensitivity of the solid-state imaging device in the imaging device closer to human visual sensitivity, a technique of arranging an optical filter that shields a part of infrared or ultraviolet light in front of the solid-state imaging device is known.

[0003] Conventionally, as such an optical filter, one that shields infrared or ultraviolet light by utilizing light reflection of a dielectric multilayer film has been common. On the other hand, in recent years, an optical filter provided with a film containing a light-absorbing compound has attracted attention. Since the transmittance characteristics of an optical filter provided with a film containing a light-absorbing compound are less affected by the incident angle, a good image with little change in color can be obtained even when light is incident obliquely on the optical filter in an imaging device. In addition, a light-absorbing type optical filter that does not use a light reflection film can suppress the occurrence of ghosts and flares caused by multiple reflections by the light reflection film, and thus it is easy to obtain a good image in backlight conditions or night scene photography. In addition, an optical filter provided with a film containing a light absorbent is also advantageous in terms of miniaturization and thinning of the imaging device.

[0004] As such a light-absorbing compound, a light-absorbing compound formed by phosphonic acid and copper ions is known. For example, Patent Document 1 describes an optical filter provided with a UV-IR absorption layer capable of absorbing infrared rays and ultraviolet rays. The UV-IR absorption layer contains a UV-IR absorbent formed by phosphonic acid and copper ions. Further, Patent Document 2 describes a method for manufacturing an optical filter provided with a light-absorbing layer containing a light-absorbing compound formed by phosphonic acid and copper ions. According to the manufacturing method, a coating film is formed on a substrate having a surface containing an organic fluorine compound, and the coating film is cured to form a light-absorbing layer. Thereafter, the light-absorbing layer is peeled off from the substrate to obtain an optical filter.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Documents 1 and 2, nothing has been studied about an article in which a light-absorbing film is attached to a frame. Therefore, the present disclosure provides an optical filter including a frame and a light-absorbing film that can exhibit good resistance to changes in environmental conditions such as temperature changes.

Means for Solving the Problems

[0007] The present invention provides a frame having through holes, and a light-absorbing film disposed so as to close the through holes and containing a light-absorbing compound, and the average value of the Young's modulus of the light-absorbing film measured according to the continuous stiffness measurement method is 2.5 GPa or less. an optical filter.

[0008] Furthermore, the present invention an image sensor, a lens that transmits light from a subject and condenses it onto the image sensor, and the above optical filter, and provides an imaging device.

[0009] Furthermore, the present invention supplies a resin composition containing a light-absorbing compound so as to close the through-hole of a frame having a through-hole, cures the resin composition to form a light-absorbing film, and provides a method for manufacturing an optical filter, wherein an average value of Young's modulus of the light-absorbing film measured according to a continuous rigidity measurement method is 2.5 GPa or less. a method for manufacturing an optical filter.

Advantages of the Invention

[0010] The above optical filter can exhibit good resistance to changes in environmental conditions such as temperature changes.

Brief Description of the Drawings

[0011]

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DETAILED DESCRIPTION OF THE INVENTION

[0012] Since the optical filters described in Patent Documents 1 and 2 are in the form of a plate or a film, for example, when these optical filters are mounted on a camera module, it is understood that first, the optical filter needs to be cut into a desired size. In this case, it is conceivable to adhere the cut optical filter to a predetermined frame to produce a framed filter, and then adhere and incorporate this framed filter into the camera module. Such cutting or adhesion of the optical filter requires large-scale equipment or complex and delicate work. In addition, the process of producing such a framed filter is not easily improved in yield and is prone to productivity problems. In particular, due to the difference between the material of the frame and the material of the optical filter, when the environment of the framed filter changes, such as a temperature change, a difference is likely to occur between the amount of expansion and contraction of the optical filter and the amount of expansion and contraction of the frame. As a result, the optical filter may crack or the optical filter may come off the frame.

[0013] Therefore, the inventors of the present invention repeatedly studied day and night about a configuration that can exhibit good resistance to changes in environmental conditions such as temperature changes while including a frame and a light absorption film. As a result of repeating a great deal of trial and error, the inventors of the present invention finally devised the optical filter according to the present invention.

[0014] Hereinafter, embodiments of the present invention will be described. Note that the following description relates to an example of the present invention, and the present invention is not limited thereto.

[0015] FIG. 1A is a plan view of an example of an optical filter according to the present invention, and FIG. 1B is a cross-sectional view of the optical filter along a plane perpendicular to the paper surface passing through line IB-IB of FIG. 1A.

[0016] As shown in FIGS. 1A and 1B, the optical filter 1 includes a frame 10 and a light absorption film 20. The frame 10 has a through hole 12. The light absorption film 20 is disposed so as to close the through hole 12 and contains a light absorption compound. The average value of the Young's modulus of the light absorption film 20 measured according to the continuous stiffness measurement method is 2.5 GPa or less. Thereby, the optical filter 1 can exhibit good resistance to environmental changes such as temperature changes. For this reason, in the optical filter 1, even when the temperature of the environment of the optical filter 1 changes, the light absorption film 20 is less likely to crack, and the light absorption film 20 is less likely to come off from the frame 10. The average value of the Young's modulus of the light absorption film 20 can be determined, for example, according to the method described in the examples. For details of the nanoindentation method (continuous stiffness measurement method), reference can be made to International Publication No. 2019 / 044758 and Japanese Patent Application Laid-Open No. 2015-174270.

[0017] The average value of the Young's modulus of the light absorption film 20 is desirably 2.4 GPa or less, and more desirably 2.2 GPa or less. The Young's modulus of the light absorption film 20 may be, for example, 0.1 GPa or more and may be 0.4 GPa or more.

[0018] The average value of the hardness of the light absorption film 20 measured according to the continuous rigidity measurement method is not limited to a specific value. The average value of the hardness of the light absorption film 20 is, for example, 0.06 GPa or less. The average value of the hardness may be 0.005 GPa to 0.06 GPa.

[0019] The material of the frame 10 is not limited to a specific material. The material of the frame 10 may be a metallic material such as stainless steel, iron, and aluminum, may be a resin, may be a composite material, or may be ceramics. The metallic material may be an alloy such as an aluminum alloy. Examples of the resin are nylon, polyphenylene sulfide (PPS), polyethylene terephthalate (PET), vinyl chloride resin (PVC), acrylic resin, acrylonitrile-butadiene-styrene resin (ABS), polyethylene, polyester, polypropylene, polyolefin, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyimide, and epoxy resin. Further, the composite material is, for example, a material in which fillers or fibers are dispersed in a base resin. The ceramics contain, for example, alumina or zirconia.

[0020] The average linear expansion coefficient of the material forming the frame 10 at 0°C to 60°C is not limited to a specific range. The average linear expansion coefficient is, for example, 0.2×10 -5 [ / °C] to 25×10 -5 [ / °C]. Thereby, the optical filter 1 can more reliably exhibit good resistance to environmental changes such as temperature changes. The average linear expansion coefficient of the material forming the frame 10 at 0°C to 60°C is desirably 1.0×10 -5 [ / °C] to 25×10 -5 [ / °C], and more desirably 4.0×10 -5 [ / °C] to 16×10 -5 [ / °C].

[0021] When the material of the frame 10 is a metallic material, the average linear expansion coefficient of any metallic material within the temperature range of 0°C to 60°C is, for example, 1.0×10 -5 [ / °C] to 3.0×10 -5[ / °C]. When the metal material is an aluminum alloy such as aluminum and duralumin within the temperature range of 0°C to 60°C, the average linear expansion coefficient is 2.3×10 -5 [ / °C] to 2.8×10 -5 [ / °C]. When the metal material is iron and steel, it is 1.0×10 -5 [ / °C] to 1.3×10 -5 [ / °C]. When the metal material is stainless steel, it is 1.0×10 -5 [ / °C] to 1.8×10 -5 [ / °C]. The average linear expansion coefficient of the metal frame within a predetermined temperature range can be measured in accordance with Japanese Industrial Standard JIS R3251-1995.

[0022] When the material of the frame 10 is resin, the average linear expansion coefficient within the temperature range of 0°C to 60°C is, for example, 1.0×10 -5 [ / °C] to 25×10 -5 [ / °C]. When the resin is polyethylene (PE), the average linear expansion coefficient of the resin within the temperature range of 0°C to 60°C is 10×10 -5 [ / °C] to 22×10 -5 [ / °C]. When the resin is polypropylene (PP), it is 5×10 -5 [ / °C] to 11×10 -5 [ / °C]. When the resin is acrylonitrile-butadiene-styrene (ABS), it is 6×10 -5 [ / °C] to 13×10 -5 [ / °C]. When the resin is polymethyl methacrylate (PMMA), it is 5×10 -5 [ / °C] to 10×10 -5 [ / °C]. When the resin is polyamide (PA), it is 5×10 -5 [ / °C] to 15×10 -5 [ / °C]. When the resin is epoxy resin (EP), it is 4×10 -5 [ / °C] to 7×10 -5 [ / °C]. When the resin is polyetheretherketone (PEEK), it is 3.6×10 -5 [ / °C] to 5×10 -5[ / °C], and when the resin is polyetherimide (PEI), it is 4.2×10 -5 [ / °C] to 5.9×10 -5 [ / °C], and when the resin is polyethylene terephthalate (PET), it is 5×10 -5 [ / °C] to 7×10 -5 [ / °C], and when the resin is polyphenylene sulfide (PPS), it is 4×10 -5 [ / °C] to 6×10 -5 [ / °C]. Also, the frame 10 may be formed of an engineering plastic among these. The average coefficient of thermal expansion of the frame in the temperature range of 0°C to 60°C may be 3.5×10 -5 [ / °C] to 15×10 -5 [ / °C]. The average coefficient of linear expansion of the resin frame within a predetermined temperature range can be measured in accordance with JIS R3251-1995.

[0023] The material of the frame 10 may be ceramics as required. The average coefficient of linear expansion of ceramics within the temperature range of 0°C to 60°C is such that when the ceramics is Al 2 O 3 (alumina), it is 0.55×10 -5 [ / °C] to 0.7×10 -5 [ / °C], and when the ceramics is ZrO 2 (zirconia), it is 0.7×10 -5 [ / °C] to 0.8×10 -5 [ / °C], and when the ceramics is SiC (silicon carbide), it is 0.28×10 -5 [ / °C] to 0.3×10 -5 [ / °C]. The average coefficient of linear expansion of the ceramic frame within a predetermined temperature range can be measured in accordance with JIS R3251-1995.

[0024] The method for measuring the average linear expansion coefficient of the frame 10 is not limited to a specific method. The average linear expansion coefficient of the frame 10 can be measured, for example, in accordance with JIS R3251-1995 using a laser thermal dilatometer LIX-2L type manufactured by Advantech Co., Ltd. In this case, a measurement sample can be prepared by sandwiching the frame from both ends with a pair of quartz chips. The environment of the measurement sample is filled with low-pressure high-purity He gas, and while changing the temperature of the environment, the change in the length of the sample is measured by the Michelson-type laser light interference method, whereby the average thermal expansion coefficient of the frame at 0°C to 60°C can be obtained. In this case, the heating rate is set to, for example, 2°C / min. The diameter of the measurement sample sandwiched by the quartz chips is, for example, 3 mm to 6 mm, and the length of the sample is, for example, 10 mm to 15 mm.

[0025] The dimension of the frame 10 in the thickness direction of the light absorption film 20 is not limited to a specific value. The dimension is, for example, 0.2 mm to 2 mm.

[0026] The number of through holes 12 in the frame 10 is not limited to a specific value. The number may be 1 or may be 2 or more.

[0027] The size and shape of the through hole 12 in the plan view of the optical filter 1 are not limited to a specific aspect. For example, when the optical filter 1 is used together with an imaging device, the size of the through hole 12 in the plan view of the optical filter 1 can be determined according to the size of the imaging device or the size of the image circle.

[0028] Examples of the shape of the through hole 12 in the plan view of the optical filter 1 may be circular, substantially circular, elliptical, substantially elliptical, triangular, square, rectangular, and quadrilaterals such as rhombus, or other polygons such as pentagon and hexagon. For example, when the optical filter 1 is used together with an imaging device, the shape of the through hole 12 in the plan view of the optical filter 1 can be adjusted to a shape corresponding to the shape of the imaging device.

[0029] As shown in FIG. 1B, the frame 10 has a first surface 14. The first surface 14 is in contact with the through-hole 12 and is formed along a plane parallel to the main surface of the light absorption film 20. The first surface 14 is formed, for example, in an annular shape.

[0030] The frame 10 has, for example, at least one of a convex portion and a concave portion in contact with the through-hole 12. As shown in FIG. 1B, the frame 10 includes, for example, a convex portion 16 in contact with the through-hole 12. The convex portion 16 protrudes toward the center of the through-hole 12 in a direction parallel to the main surface of the light absorption film 20. For example, the first surface 14 is formed by the end surface of the convex portion 16 in the thickness direction of the light absorption film 20. For example, one end of the convex portion 16 in the thickness direction of the light absorption film 20 and one end of the frame 10 in the thickness direction of the light absorption film 20 are located in the same plane.

[0031] Note that the main surface means the "main surface" which has a larger area than other surfaces when the object having the main surface is a plate-like body, and that surface is referred to as the main surface.

[0032] In the frame 10, the through-hole 12 is formed such that a prismatic space having a volume of A×B×(t1 - t2) and a prismatic space having a volume of a×b×t2 are connected. When the shape of the through-hole 12 in plan view is a square, A = B and a = b. t1 is the dimension of the frame 10 in the thickness direction of the light absorption film 20, and t2 is the distance between one end of the frame 10 and the first surface 14 in the thickness direction of the light absorption film 20. Each of A and B is, for example, 5 to 30 mm, and each of a and b is, for example, 3 to 25 mm. t1 is, for example, 0.2 to 2 mm, may be 0.2 to 1.5 mm, or may be 0.3 to 0.9 mm. t2 is, for example, 0.1 to 0.5 mm, or may be 0.1 to 0.25 mm.

[0033] The ratio of the thickness t1 of the light absorption film 20 (the value obtained by dividing the thickness of the light absorption film 20 by t1) is not limited to a specific value. The ratio may be 0.6 or more, and may be 1 or more. The ratio of the thickness t1 of the light absorption film 20 may be 2 or less, and may be 1.5 or less. Further, the ratio of the thickness t1 of the light absorption film 20 may be 0.3 to 0.6, and may further be 0.39 to 0.44.

[0034] The ratio of the thickness t2 of the light absorption film 20 (the value obtained by dividing the thickness of the light absorption film 20 by t2) may be greater than 1 and 2 or less, may be 1.2 to 1.6, and may further be 1.3 to 1.46. When the thickness of the light absorption film 20 and t2 are in such a relationship, the contact area of the light absorption film 20 with the inner surface of the through hole 12 can be increased, and the adhesion of the light absorption film 20 to the frame 10 can be improved.

[0035] Note that FIG. 1B is a (cross-sectional) view showing one embodiment of the optical filter 1 according to the present application. The embodiment of the optical filter 1 according to the present application will be described more specifically with reference to FIG. 1B. In FIG. 1B, the frame 10 is in the shape of a flat plate having a first end face 25 and a second end face 26 in the thickness direction. The first end face 25 is the upper end face, and the second end face 26 is the lower end face. Each of the first end face 25 and the second end face 26 is a flat surface. The through hole 12 is formed through the frame 10 in the thickness direction. The thickness of the frame 10 is t1. The through hole 12 includes a convex portion 16 that protrudes toward the inside of the through hole 12. The convex portion 16 includes a first surface 14 and a surface 17. The first surface 14 is a surface substantially parallel to the second end face 26. The surface 17 is a surface perpendicular to the second end face 26 and the first surface 14. The length of the frame 10 in the thickness direction of the frame 10 between the second end face 26 and the first surface 14 is t2. The light absorption film 20 is formed inside the through hole 12. The light absorption film 20 is in the shape of a flat plate having a first main surface 22 and a second main surface 24 that are parallel to each other and are separated from each other in the thickness direction. The first main surface 22 is the upper main surface, and the second main surface 24 is the lower main surface. Each of the first main surface 22 and the second main surface 24 is a flat surface. The second main surface 24 of the light absorption film 20 is substantially flush with the second end face 26 of the frame 10. "Flush" means a state in which two or more surfaces are smoothly connected without a step. The thickness of the light absorption film 20 is the length of the light absorption film 20 between the first main surface 22 and the second main surface 24 in the thickness direction of the light absorption film 20. Further, the first main surface 22 of the light absorption film 20 is formed at a position closer to the first end face 25 than the first surface 14 of the frame 10, and the thickness of the light absorption film 20 is greater than the length t2. Further, the light absorption film 20 is in contact with two surfaces, i.e., the surface 17 and the first surface 14, that constitute the convex portion 16.

[0036] Regardless of the specific configuration of the above embodiment, in the optical filter according to the present application, when there is a convex portion or a concave portion inside the through hole in which the light absorption film is disposed, the light absorption film may be in contact with a part or all of the convex portion or the concave portion. Alternatively, the light absorption film may be in contact with at least two surfaces among the surfaces that constitute the convex portion or the concave portion.

[0037] The color of the surface of the frame 10 is not limited to a specific color. The portion of the frame 10 in contact with the through-hole 12 is, for example, black, and the entire surface color of the frame 10 may be black. In this case, for example, when the optical filter 1 is used in an imaging device, the re-reflection of light in the frame 10 can be suppressed. The frame 10 may be colored with a color that can suppress the re-reflection of light.

[0038] The surface of the frame 10 may be a matte surface with suppressed gloss, or minute irregularities may be formed on the surface of the frame 10 so that light is diffusely reflected. Thereby, the light re-reflected on the surface of the frame 10 can be diffused. As a result, when the optical filter 1 is used in an imaging device, it is easy to suppress ghosts or flares formed by direct reflection of light.

[0039] The frame 10 may be modified like the frame 10x shown in FIGS. 2A and 2B. The frame 10x is configured in the same manner as the frame 10 except for the parts to be specifically described. The components of the frame 10x that are the same as or corresponding to the components of the frame 10 are given the same reference numerals. The shape of the through-hole 12 in the plan view of the frame 10x is an ellipse. In the frame 10x, the through-hole 12 is formed such that an elliptical columnar space with a volume of π(S1 / 2)×(S2 / 2)×(t3 - t4) and an elliptical columnar space with a volume of π(s1 / 2)×(s2 / 2)×t4 are continuous. Each of S1 and s1 is the length of the major axis of the ellipse, and each of S2 and s2 is the length of the minor axis of the ellipse. When the shape of the through-hole 12 in the plan view is a circle, S1 = S2 and s1 = s2. t3 is the dimension of the frame 10x in the thickness direction of the light absorption film 20, and t4 is the distance between one end of the frame 10x and the first surface 14 in the thickness direction of the light absorption film 20. Each of S1 and S2 is, for example, 5 to 30 mm, and each of s1 and s2 is, for example, 3 to 25 mm. t3 is, for example, 0.2 to 2 mm, may be 0.2 to 1.5 mm, or may be 0.3 to 0.9 mm. t4 is, for example, 0.1 to 0.5 mm, may be 0.1 to 0.25 mm.

[0040] The ratio of the thickness t3 of the light absorption film 20 (the value obtained by dividing the thickness of the light absorption film 20 by t3) is not limited to a specific value. The ratio may be 0.6 or more, or may be 1 or more. Also, the ratio of the thickness t3 of the light absorption film 20 may be 2 or less, or may be 1.5 or less. The ratio of the thickness t3 of the light absorption film 20 may be 0.3 to 0.6, or may further be 0.39 to 0.44.

[0041] The ratio of the thickness t4 of the light absorption film 20 (the value obtained by dividing the thickness of the light absorption film 20 by t4) is greater than 1. The ratio may be 2 or less, may be 1.2 to 1.6, or may further be 1.3 to 1.46. When the thickness of the light absorption film 20 and t4 are in such a relationship, the contact area of the light absorption film 20 with the inner surface of the through hole 12 can be increased, and the adhesion of the light absorption film 20 to the frame 10x can be improved.

[0042] The frame 10 is not limited to a specific embodiment as long as it has the through hole 12. The frame 10 may be modified, for example, like the frames 10a to 10i shown in FIGS. 3A to 3I. The frames 10a to 10i are configured in the same manner as the frame 10 except for the parts that will be specifically described. The components of the frames 10a to 10i that are the same as or corresponding to the components of the frame 10 are given the same reference numerals. FIGS. 3A to 3I each show a cross section of the frames 10a to 10i formed along a plane including the axis of the through hole 12 and parallel to the axis.

[0043] In the frame 10a shown in FIG. 3A, the through hole 12 is formed by an inner surface extending in a direction perpendicular to the main surface of the light absorption film 20 (not shown). In the frame 10b shown in FIG. 3B, the through hole 12 is formed as a tapered hole. In the frame 10c shown in FIG. 3C, the through hole 12 has a portion formed as a tapered hole and a portion formed by an inner surface extending in a direction perpendicular to the main surface of the light absorption film 20. Each of the frame 10d shown in FIG. 3D and the frame 10e shown in FIG. 3E includes a convex portion 16 in contact with the through hole 12. The convex portion 16 is formed in an annular shape around the through hole 12. The convex portion 16 in the frame 10d has, for example, a pair of side surfaces parallel to the main surface of the light absorption film 20 and end surfaces connecting these side surfaces. For example, one of the pair of side surfaces in the convex portion 16 forms the first surface 14. The convex portion 16 in the frame 10e has a tapered shape.

[0044] Each of the frame 10f shown in FIG. 3F and the frame 10g shown in FIG. 3G includes a concave portion 18 in contact with the through hole 12. The concave portion 18 is formed in an annular shape and is included in a part of the through hole 12. The concave portion 18 in the frame 10f has, for example, a pair of side surfaces parallel to the main surface of the light absorption film 20 and facing each other. One of the pair of side surfaces may form the first surface 14. The concave portion 18 in the frame 10g forms a wedge-shaped groove.

[0045] In the frame 10h shown in FIG. 3H, a pair of inner surfaces extending in directions perpendicular to each other and in contact with the through-hole 12 may be connected by surfaces inclined with respect to those inner surfaces. For example, in a cross-section of the frame 10h formed along a plane including the axis of the through-hole 12 and parallel to the axis, the contours of a pair of inner surfaces extending in directions perpendicular to each other are connected by contours inclined at an angle of 45° with respect to both of those contours. A pair of inner surfaces extending in directions perpendicular to each other and in contact with the through-hole 12 may be connected by rounded curved surfaces. The above-described shape of the frame 10h can be said to be a chamfered shape with an appropriate amount of C-plane or R-plane taken with respect to a corner portion of a part of the inner surface forming the through-hole having the convex portion 16 in the frame of the optical filter represented in FIG. 1B. The size of the C-plane may be C0.01 to C0.25, or may be C0.025 to C0.1. The size of the R-plane may be R0.01 to R0.25, or may be R0.025 to R0.1. Note that such chamfering may be performed on a part of the inner surface forming the through-hole of the frames in FIGS. 3A to 3G above.

[0046] The frame 10i shown in FIG. 3I includes a convex portion 16 in contact with the through-hole 12. The convex portion 16 has a surface formed in a tapered shape from both end faces of the frame 10i in a direction perpendicular to the main surface of the light absorption film 20 (not shown).

[0047] As shown in FIG. 1B, the light absorption film 20 has, for example, a thickness smaller than the dimension of the frame 10 in the thickness direction of the light absorption film 20. In this case, even when the thickness of the light absorption film 20 is small, since the light absorption film 20 is integrated with the frame 10, the handling of the optical filter 1 is easy.

[0048] The thickness of the light absorption film 20 is not limited to a specific thickness. The light absorption film 20 has, for example, a thickness of 1 μm to 1000 μm.

[0049] The thickness of the light absorption film 20 may be 10 μm to 500 μm, or may be 50 μm to 300 μm.

[0050] As shown in FIG. 1B, the light absorption film 20 has, for example, a first main surface 22. The first main surface 22 is formed between one end and the other end of the frame 10 in the thickness direction of the light absorption film 20. In this case, it is possible to move the optical filter 1 without touching the first main surface 22, and the yield of the product provided with the optical filter 1 is likely to increase. The first main surface 22 is formed so as to cover the first surface 14, for example, in the thickness direction of the light absorption film 20. The first main surface 22 may be formed to be in the same plane as the first surface 14.

[0051] As shown in FIG. 1B, the light absorption film 20 has, for example, a second main surface 24. The second main surface 24 is formed to be in the same plane as one end of the frame 10 in the thickness direction of the light absorption film 20, for example. In this case, no step is caused by the second main surface 24 of the light absorption film 20 in the optical filter 1, and when carrying the optical filter 1, it is possible to prevent the light absorption film 20 from contacting other members and being damaged. As a result, the yield of the product provided with the optical filter 1 is likely to increase. Further, since the light absorption film 20 exists at one end of the through hole 12 in the thickness direction of the light absorption film 20, it is possible to prevent light from directly irradiating the inner surface of the frame 10 in contact with the through hole 12. The second main surface 24 may be formed between one end and the other end of the frame 10 in the thickness direction of the light absorption film 20.

[0052] As shown in FIG. 1B, the light absorption film 20 overlaps with the convex portion 16 in the thickness direction of the light absorption film 20. As shown in FIGS. 3J to 3P, for example, the light absorption film 20 may overlap at least a part of the convex portion or at least a part of the concave portion formed inside the through hole of the frame in the thickness direction of the light absorption film 20.

[0053] FIGS. 3J and 3K respectively show optical filters obtained by forming the light absorption film 20 inside the through hole 12 of the frame 10d shown in FIG. 3D. In the optical filter shown in FIG. 3J, the light absorption film 20 overlaps with the entire convex portion 16 in the thickness direction of the light absorption film 20. In the optical filter shown in FIG. 3K, the light absorption film 20 overlaps with a part of the convex portion 16 in the thickness direction of the light absorption film 20.

[0054] In the optical filter shown in FIG. 3J, the light absorption film 20 is in contact with three surfaces (two surfaces parallel to the end surface of the frame 10d and a surface perpendicular to those surfaces) that constitute the convex portion 16 inside the through hole of the frame 10d. In the optical filter shown in FIG. 3K, the light absorption film 20 is in contact with two surfaces (one surface parallel to the end surface of the frame 10d and a surface perpendicular to that surface) that constitute the convex portion 16 inside the through hole of the frame 10d.

[0055] FIG. 3L shows an optical filter obtained by forming the light absorption film 20 inside the through hole 12 of the frame 10e shown in FIG. 3E. In the optical filter shown in FIG. 3L, the light absorption film 20 overlaps the entire convex portion 16 in the thickness direction of the light absorption film 20. In the optical filter shown in FIG. 3L, the light absorption film 20 may overlap a part of the convex portion 16 in the thickness direction of the light absorption film 20.

[0056] In the optical filter shown in FIG. 3L, the light absorption film 20 is in contact with two surfaces that constitute a triangular convex portion protruding toward the center of the through hole inside the through hole of the frame 10e. Also, in the frame 10e included in the optical filter shown in FIG. 3L, although it has a convex portion inside the through hole, it does not have a surface parallel to one end surface of the frame like the frame included in the optical filter such as FIG. 1B. Such a configuration is also included in the present invention.

[0057] FIG. 3M and FIG. 3N each show an optical filter obtained by forming the light absorption film 20 inside the through hole 12 of the frame 10f shown in FIG. 3F. In the optical filter shown in FIG. 3M, the light absorption film 20 overlaps the entire concave portion 18 in the thickness direction of the light absorption film 20. In the optical filter shown in FIG. 3N, the light absorption film 20 overlaps a part of the concave portion 18 in the thickness direction of the light absorption film 20.

[0058] In the optical filter shown in FIG. 3M, the light absorption film 20 is in contact with three surfaces (two surfaces parallel to the end surface of the frame 10f and a surface perpendicular to the surface) that constitute the concave portion 18 inside the through hole of the frame 10f. In the optical filter shown in FIG. 3N, the light absorption film 20 is in contact with two surfaces (one surface parallel to the end surface of the frame 10d and a surface perpendicular to the surface) that constitute the concave portion 18 inside the through hole of the frame 10f.

[0059] FIG. 3O shows an optical filter obtained by forming a light absorption film 20 inside the through hole 12 of the frame 10g shown in FIG. 3G. In the optical filter shown in FIG. 3O, the light absorption film 20 overlaps the entire concave portion 18 in the thickness direction of the light absorption film 20. In the optical filter shown in FIG. 3O, the light absorption film 20 may overlap a part of the concave portion 18 in the thickness direction of the light absorption film 20.

[0060] In the optical filter shown in FIG. 3O, the light absorption film 20 is in contact with two surfaces that constitute a triangular concave portion that is recessed toward the outside of the through hole inside the through hole of the frame 10g. Further, in the frame 10g included in the optical filter shown in FIG. 3O, although it has a concave portion inside the through hole, it does not have a surface parallel to one end surface of the frame like the frame included in the optical filter such as FIG. 1B. Such a configuration is also included in the present invention.

[0061] FIG. 3P shows an optical filter obtained by forming a light absorption film 20 inside the through hole 12 of the frame 10i shown in FIG. 3I. In the optical filter shown in FIG. 3P, the light absorption film 20 overlaps a part of the convex portion 16 in the thickness direction of the light absorption film 20. In the optical filter shown in FIG. 3P, the light absorption film 20 may overlap the entire convex portion 16 in the thickness direction of the light absorption film 20.

[0062] In the optical filter shown in FIG. 3P, the light absorption film 20 is in contact with three surfaces that form a trapezoidal convex portion protruding toward the center of the through hole inside the through hole of the frame 10i. Also, in the frame 10i included in the optical filter shown in FIG. 3P, although it has a convex portion inside the through hole, it does not have a surface parallel to one end surface of the frame like the frame included in the optical filter such as FIG. 1B. Such a configuration is also included in the present invention.

[0063] As described above, in the optical filters according to FIGS. 1B and 3J to 3P, among the surfaces constituting the convex or concave portions inside the through holes of the frames included in the optical filters, at least two surfaces are in contact with the light absorption film.

[0064] The light absorption film 20 is not limited to a specific film as long as it can absorb light of a predetermined wavelength. The light absorption film 20 has a transmittance spectrum that satisfies, for example, the following requirements (I), (II), (III), (IV), (V), (VI), and (VII). (I) There is a first cut-off wavelength showing a transmittance of 50% in the wavelength range of 380 nm to 440 nm. (II) There is a second cut-off wavelength showing a transmittance of 50% in the wavelength range of 600 nm to 720 nm. (III) The maximum transmittance in the wavelength range of 300 nm to 350 nm is 1% or less. (IV) The average transmittance in the wavelength range of 450 nm to 600 nm is 75% or more. (V) The maximum transmittance in the wavelength range of 750 nm to 1000 nm is 5% or less. (VI) The maximum transmittance in the wavelength range of 800 nm to 950 nm is 4% or less. (VII) The transmittance at a wavelength of 1100 nm is 20% or less.

[0065] In this specification, "the maximum transmittance in the wavelength range of X nm to Y nm is A% or less" is synonymous with the transmittance being A% or less throughout the wavelength range of X nm to Y nm.

[0066] Regarding the requirement of (I) above, the first cut-off wavelength preferably exists in the range of wavelengths from 385 nm to 435 nm, more preferably in the range of wavelengths from 390 nm to 430 nm.

[0067] Regarding the requirement of (II) above, the second cut-off wavelength preferably exists in the range of wavelengths from 610 nm to 700 nm, more preferably in the range of wavelengths from 620 nm to 680 nm.

[0068] Regarding the requirement of (IV) above, the average transmittance at wavelengths from 450 nm to 600 nm is preferably 78% or more, more preferably 80% or more.

[0069] Regarding the requirement of (V) above, the maximum transmittance in the range of wavelengths from 750 nm to 1000 nm is preferably 3% or less, more preferably 1% or less.

[0070] Regarding the requirement of (VI) above, the maximum transmittance in the range of wavelengths from 800 nm to 950 nm is preferably 2% or less, more preferably 0.5% or less.

[0071] Regarding the requirement of (VII) above, the transmittance at a wavelength of 1100 nm is preferably 15% or less, more preferably 10% or less.

[0072] The light absorption film 20 is fixed to the frame 10, for example, by directly contacting the inner surface of the frame 10. In other words, there is no adhesive layer between the light absorption film 20 and the frame 10. The light absorption film 20 may be fixed to the frame 10 with an adhesive.

[0073] The light-absorbing compound in the light absorption film 20 is not limited to a specific compound as long as it can absorb light of a predetermined wavelength. The light-absorbing compound may contain, for example, a phosphonic acid represented by the following formula (a) and a copper component.

[0074]

Chemical formula

[0075] In the light absorption film 20, for example, a phosphonic acid represented by the formula (a) coordinates to a copper component to form a light-absorbing compound. For example, fine particles containing at least a light-absorbing compound are formed in the light absorption film 20. In this case, the fine particles are dispersed in the light absorption film 20 without aggregating with each other. The average particle diameter of the fine particles is, for example, 5 nm to 200 nm. If the average particle diameter of the fine particles is 5 nm or more, no special process is required for miniaturization of the fine particles, and the structure of the fine particles containing at least a light-absorbing compound is less likely to be broken. Also, the fine particles are well dispersed in the light absorption film 20. Further, when the average particle diameter of the fine particles is 200 nm or less, the influence of Mie scattering can be reduced, the transmittance of visible light of the light absorption film 20 can be improved, and deterioration of characteristics such as contrast and haze of an image captured by an imaging device can be suppressed. The average particle diameter of the fine particles is desirably 100 nm or less. In this case, since the influence of Rayleigh scattering is reduced, the transparency of the light absorption film 20 with respect to visible light is enhanced. Further, the average particle diameter of the fine particles is more desirably 75 nm or less. In this case, the transparency of the light absorption film 20 with respect to visible light is particularly high. Note that the average particle diameter of the fine particles can be measured by applying the dynamic light scattering method to the composition for the light absorption film 20.

[0076] The light absorption film 20 contains, for example, a hydrolysis condensate of an alkoxysilane. In this case, the light absorption film 20 has a strong skeleton having a siloxane bond (-Si-O-Si-).

[0077] The hydrolysis condensate of the alkoxysilane contained in the light absorption film 20 includes, for example, the hydrolysis condensate of a dialkoxysilane. Thereby, a strong skeleton having a siloxane bond is formed in the light absorption film 20, and the light absorption film 20 is likely to have desired flexibility due to the organic functional groups derived from the dialkoxysilane. For this reason, cracks and chipping are less likely to occur when cutting the light absorption film 20. In addition, when an external force is applied so that the light absorption film 20 bends, the light absorption film 20 is less likely to break. Further, even if the difference between the coefficient of thermal expansion of the frame 10 and the coefficient of thermal expansion of the light absorption film 20 is large, the light absorption film 20 can be flexibly deformed according to the expansion and contraction of the frame 10. For this reason, it is less affected by thermal stress, and problems such as cracks and peeling of the light absorption film 20 from the frame 10 are less likely to occur in the heat cycle test.

[0078] The hydrolysis condensate of the dialkoxysilane is not limited to the hydrolysis condensate of a specific dialkoxysilane. This hydrolysis condensate is derived from, for example, a dialkoxysilane having a hydrocarbon group having 1 to 6 carbon atoms bonded to a silicon atom. The dialkoxysilane may have a halogenated hydrocarbon group. In the halogenated hydrocarbon group, at least one hydrogen atom in the hydrocarbon group having 1 to 6 carbon atoms bonded to the silicon atom is substituted with a halogen atom.

[0079] The hydrolysis condensate of the dialkoxysilane may be derived from, for example, an alkoxysilane represented by the following formula (b). In this case, it is more likely that the desired flexibility is imparted to the light absorption film 20. (R 2 ) 2 -Si-(OR 3 ) 2 (b) [In the formula, R 2 are each independently an alkyl group having 1 to 6 carbon atoms, and R 3 are each independently an alkyl group having 1 to 8 carbon atoms.]

[0080] The hydrolytic condensate of dialkoxysilane may be, for example, a hydrolytic condensate of dimethyldiethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, or 3-glycidoxypropylmethyldiethoxysilane.

[0081] The hydrolytic condensate of alkoxysilane may further contain at least one hydrolytic condensate of tetraalkoxysilane and trialkoxysilane. Thereby, a dense structure is likely to be formed by siloxane bonds in the light absorption film 20.

[0082] The hydrolytic condensate of alkoxysilane may further contain a hydrolytic condensate of tetraalkoxysilane and a hydrolytic condensate of trialkoxysilane. Thereby, a dense structure is more reliably likely to be formed by siloxane bonds in the light absorption film 20.

[0083] The tetraalkoxysilane or trialkoxysilane for the hydrolytic condensate of alkoxysilane contained in the light absorption film 20 is not limited to a specific alkoxysilane. For example, the tetraalkoxysilane or trialkoxysilane for the hydrolytic condensate of alkoxysilane contained in the light absorption film 20 is at least one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, n-propyltriethoxysilane, n-propyltrimethoxysilane, hexyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-isocyanatopropyltrimethoxysilane.

[0084] The amounts of dialkoxysilane and the hydrolytic condensate of dialkoxysilane in the alkoxysilane and the hydrolytic condensate of alkoxysilane contained in the light absorption film 20 are not limited to specific values. The ratio of the content of the dialkoxysilane and the hydrolytic condensate of dialkoxysilane contained in the light absorption film 20 to the total amount of the alkoxysilane and the hydrolytic condensate of alkoxysilane contained in the light absorption film 20 is, on a mass basis converted to their complete hydrolytic condensates, for example, 6 to 48%. Thereby, more reliably, the average value of the Young's modulus of the light absorption film 20 measured according to the continuous stiffness measurement method is easily adjusted to a desired range. The ratio is desirably 8 to 35%, and more desirably 10 to 30%. In this case, the light absorption film 20 is likely to have high moisture resistance. This is because a dense structure is formed by siloxane bonds, and the light-absorbing compound is less likely to aggregate in a high-humidity environment.

[0085] The light absorption film 20 further contains, for example, a phosphate ester. Due to the function of the phosphate ester, the light-absorbing compound is likely to be well dispersed in the light absorption film 20. In the light absorption film 20, the compound derived from alkoxysilane can appropriately disperse the light-absorbing compound while imparting higher moisture resistance to the light absorption film 20 compared to the phosphate ester. Therefore, by containing alkoxysilane in the light absorption film 20, the usage amount of the phosphate ester can be reduced. In the formation of the light absorption film 20, when the alkoxysilane present around the light-absorbing compound reacts with the dialkoxysilane, the light absorption film 20 is likely to be homogeneous and have high density. Note that the light absorption film 20 may not contain a phosphate ester.

[0086] The phosphate ester is, for example, a phosphate ester having a polyoxyalkyl group. The phosphate ester having a polyoxyalkyl group is not limited to a specific phosphate ester. The phosphate ester having a polyoxyalkyl group is, for example, Prisurf A208N: polyoxyethylene alkyl (C12, C13) ether phosphate ester, Prisurf A208F: polyoxyethylene alkyl (C8) ether phosphate ester, Prisurf A208B: polyoxyethylene lauryl ether phosphate ester, Prisurf A219B: polyoxyethylene lauryl ether phosphate ester, Prisurf AL: polyoxyethylene styrenated phenyl ether phosphate ester, Prisurf A212C: polyoxyethylene tridecyl ether phosphate ester, or Prisurf A215C: polyoxyethylene tridecyl ether phosphate ester. These are all products manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. Also, the phosphate ester may be, for example, NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate ester, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate ester, or NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester. These are all products manufactured by Nikko Chemicals Co., Ltd.

[0087] The light absorption film 20 further contains, for example, a resin. The resin is not limited to a specific resin. The resin is, for example, a silicone resin. The silicone resin is a compound having a siloxane bond in its structure. In this case, since the hydrolysis polycondensate of alkoxysilane also has a siloxane bond, the compatibility between the hydrolysis polycondensate of alkoxysilane and the resin is good in the light absorption film 20.

[0088] The resin is desirably a silicone resin containing an aryl group such as a phenyl group. When the resin contained in the light absorption film 20 is hard (rigid), as the thickness of the light absorption film 20 increases, cracks are likely to occur due to curing shrinkage during the manufacturing process of the light absorption film 20. When the resin is a silicone resin containing an aryl group, the light absorption film 20 is likely to have good crack resistance. In addition, the silicone resin containing an aryl group has high compatibility with the phosphonic acid represented by the formula (a) and is difficult to aggregate the light-absorbing compound. Specific examples of the silicone resin used as the resin include KR-255, KR-300, KR-2621-1, KR-211, KR-311, KR-216, KR-212, KR-251, and KR-5230. These are all silicone resins manufactured by Shin-Etsu Chemical Co., Ltd.

[0089] An example of the manufacturing method of the optical filter 1 is shown. The manufacturing method of the optical filter 1 includes, for example, the following steps (i) and (ii). (i) A resin composition containing a light-absorbing compound is supplied so as to block the through-hole 12 of the frame 10. (ii) The resin composition supplied in (i) is cured to form the light absorption film 20.

[0090] FIG. 4 is a flowchart for explaining an example of manufacturing the optical filter 1 according to the present embodiment. As an example, a method of manufacturing the optical filter 1 according to FIGS. 1A and 1B is explained. Note that this explanation and FIG. 4 used for the explanation explain the main part of the manufacturing method of the optical filter according to the present invention and do not reflect a specific and definite configuration.

[0091] The optical filter 1 may be manufactured by the method shown in FIG. 4. In this method, first, a substrate 30 is provided. The substrate 30 is not limited to a specific substrate. The substrate 30 may be a glass substrate, a metal substrate such as stainless steel and aluminum, a ceramic substrate such as alumina and zirconia, or a resin substrate. The substrate 30 is preferably a glass substrate. In this case, a smooth surface can be easily and inexpensively obtained.

[0092] As understood from FIG. 4, the substrate 30 has at least one flat main surface.

[0093] Next, a coating 32 is formed on the main surface of the substrate 30. The coating 32 is formed so that the peeling of the light absorption film 20 becomes easy in a later process. The coating 32 has, for example, hydrophobicity or water repellency. The coating 32 contains, for example, a fluorine compound. The substrate 30 may be subjected to a surface treatment such that the peeling of the light absorption film 20 becomes easy in a later process by a method other than the formation of the coating 32. When the main surface of the substrate 30 has the property that the peeling of the light absorption film 20 is easy, the formation of the coating 32 and other surface treatments may be omitted. For example, when the substrate 30 is a substrate made of a fluororesin, the formation of the coating 32 and other surface treatments can be omitted.

[0094] Next, a frame 10 is installed on the coating 32. In this case, the frame 10 may be fixed to the substrate 30 by a jig (not shown). A plurality of frames 10 may be installed on one substrate 30. Desirably, the frame 10 is installed in a state where they are in close contact so that no gap is generated between a part of the surface of the frame 10 and the surface of the coating 32.

[0095] As can be understood from the figure showing the cross-sectional view of the frame 10 (particularly the third one from the top) in FIG. 4, the frame 10 has a flat plate shape with two parallel flat main surfaces and has a through hole 12 drilled in the thickness direction. One of the main surfaces of the frame 10 is grounded to the flat main surface of the substrate 30 or the surface of the coating 32 formed on the main surface of the substrate 30. The frame 10 includes a convex portion 16 inside the through hole 12. Further, the convex portion 16 includes a first surface 14 parallel to the main surface of the frame 10.

[0096] Next, a predetermined amount of the light-absorbing composition 20a is supplied so as to block the through hole 12 of the frame 10. The supply amount of the light-absorbing composition 20a is adjusted so that the light-absorbing film 20 obtained by curing the light-absorbing composition 20a has a thickness capable of exhibiting desired optical characteristics such as a desired transmittance spectrum.

[0097] At this time, as can be understood from FIG. 4 (particularly the fourth or fifth one from the top), one end surface in the thickness direction of the light-absorbing film 20 is in close contact with the flat main surface of the substrate 30 or the surface of the coating 32 formed on the main surface of the substrate 30. Thus, it is planned that one main surface in the thickness direction of the light-absorbing film 20 will be substantially flush with one main surface of the frame 10.

[0098] Also, as can be understood from FIG. 4 (particularly the fourth or fifth one from the top), the end surface of the light-absorbing film 20 on the side opposite to the substrate 30 is formed by supplying the light-absorbing composition 20a so as to exceed the height of the first surface 14.

[0099] Next, the light-absorbing composition 20a is cured to form the light-absorbing film 20. For example, the light-absorbing composition 20a can be cured by heating the light-absorbing composition 20a inside a heating furnace or an oven. The curing conditions of the light-absorbing composition 20a can be adjusted according to, for example, the curing conditions of the curable resin contained in the light-absorbing composition 20a. The curing conditions may include conditions related to the temperature of the atmosphere of the light-absorbing composition 20a and conditions related to time.

[0100] As can be understood from FIG. 4, the ratio of the length t2 of the thickness of the light absorption film 20 is greater than 1. The length t2 corresponds to the distance in the thickness direction of the light absorption film 20 between one end surface of the frame 10 and the first surface 14.

[0101] Next, the light absorption film 20 is peeled off from the substrate 30 together with the frame 10. Thereby, the optical filter 1 can be obtained. When the light absorption film 20 contains an alkoxysilane or a hydrolyzate thereof, by exposing the light absorption film 20 to an atmosphere at a temperature of about 60° C. to 90° C. and a predetermined relative humidity of 90% or less, the formation of siloxane bonds in the light absorption film 20 may be promoted. As a result, the matrix of the light absorption film 20 is likely to become stronger.

[0102] As long as the light absorption film 20 can be formed, the light absorption composition 20a is not limited to a specific composition. The light absorption composition 20a contains, for example, components contained in the light absorption film 20 or precursors of components contained in the light absorption film 20. Taking the case where the light absorption compound contains the above phosphonic acid and copper component as an example, an example of a method for preparing the light absorption composition 20a will be described.

[0103] For example, when the light absorption composition 20a is R in formula (a) 11When the phosphonic acid (aryl phosphonic acid) is an aryl group, nitroaryl group, hydroxyaryl group, or halogenated aryl group, the D solution is prepared as follows. A copper salt such as copper acetate monohydrate is added to a predetermined solvent such as tetrahydrofuran (THF) and stirred to prepare solution A which is a solution of the copper salt. Next, the aryl phosphonic acid is added to a predetermined solvent such as THF and stirred to prepare solution B. When using a plurality of types of aryl phosphonic acids as the phosphonic acid represented by formula (a), each aryl phosphonic acid may be added to a predetermined solvent such as THF and stirred, and then a plurality of prepared preliminary solutions prepared for each type of aryl phosphonic acid may be mixed to prepare solution B. For example, alkoxysilane is added in the preparation of solution B. While stirring solution A, solution B is added to solution A and stirred for a predetermined time. Next, a predetermined solvent such as toluene is added to this solution and stirred to obtain solution C. Next, solution C is subjected to a solvent removal treatment for a predetermined time while being heated to obtain solution D. Thereby, components generated by the dissociation of the solvent such as THF and the copper salt such as acetic acid (boiling point: about 118 ° C) are removed, and a photoabsorbing compound is generated by the reaction of the phosphonic acid represented by formula (a) and the copper component. The temperature at which solution C is heated is determined based on the boiling point of the component to be removed dissociated from the copper salt. In the solvent removal treatment, solvents such as toluene (boiling point: about 110 ° C) used to obtain solution C also volatilize. Since it is desirable that this solvent remains to some extent in the photoabsorbing composition 20a, from this viewpoint, the addition amount of the solvent and the time of the solvent removal treatment may be determined. Note that o-xylene (boiling point: about 144 ° C) can be used instead of toluene to obtain solution C. In this case, since the boiling point of o-xylene is higher than the boiling point of toluene, the addition amount can be reduced to about one-fourth of the addition amount of toluene.

[0104] The photoabsorbing composition 20a, in formula (a), R 11When containing a phosphonic acid in which the [[ID=]] is an alkyl group (alkyl-based phosphonic acid), for example, the H solution is further prepared as follows. First, a copper salt such as copper acetate monohydrate is added to a predetermined solvent such as tetrahydrofuran (THF) and stirred to obtain an E solution which is a solution of the copper salt. Also, the alkyl-based phosphonic acid is added to a predetermined solvent such as THF and stirred to prepare an F solution. When using a plurality of types of phosphonic acids as the alkyl-based phosphonic acid, each alkyl-based phosphonic acid may be added to a predetermined solvent such as THF and then stirred, and a plurality of preliminary solutions prepared for each type of alkyl-based phosphonic acid may be mixed to prepare the F solution. For example, an alkoxysilane is further added in the preparation of the F solution. While stirring the E solution, the F solution is added to the E solution and stirred for a predetermined time. Next, a predetermined solvent such as toluene is added to this solution and stirred to obtain a G solution. Next, the G solution is subjected to a solvent removal treatment for a predetermined time while being heated to obtain an H solution. Thereby, components generated by the dissociation of the solvent such as THF and the copper salt such as acetic acid are removed. The temperature at which the G solution is heated is determined in the same manner as the C solution, and the solvent for obtaining the G solution is also determined in the same manner as the C solution.

[0105] For example, while mixing the D solution and the H solution at a predetermined ratio, an alkoxysilane is added, and if necessary, a curable resin such as a silicone resin is added to prepare the light-absorbing composition 20a. In this case, the dialkoxysilane may be added after the mixing of the D solution and the H solution. In the light-absorbing composition 20a, the aryl-based phosphonic acid and the alkyl-based phosphonic acid may react with the copper component to form a complex. Also, a part of the added phosphate ester may react with the copper component to form a complex in the same manner, or a part of the phosphate ester may react with the phosphonic acid or the copper component to form a complex. The light-absorbing film 20 formed by curing the light-absorbing composition 20a can exhibit desired light-absorbing performance due to the action of each material, particularly the copper component such as copper ions.

[0106] The optical filter 1 may be provided with other functional films on one or both main surfaces of the light absorption film 20. The functional film is, for example, an antireflection film having an antireflection or reflection reduction function. The antireflection film may be designed or fabricated, for example, to reduce the reflection of light in the visible light range where transmission is expected in the light absorption film 20. Thereby, an improvement in the transmittance of light in the visible light range is achieved, and it is easy to obtain a bright image when the optical filter 1 is used in an imaging device. The antireflection film can be obtained by forming a dielectric film with an appropriate thickness on the main surface of the light absorption film 20. Examples of the dielectric are SiO 2 TiO 2 Ti 3 N 4 Al 2 O 3 and MgO. The antireflection film may be a single-layer film of a dielectric or a multilayer film of different types of dielectrics. For example, when forming an antireflection film using a material with a low refractive index, the antireflection film can exhibit a good antireflection function with a smaller number of layers. For example, when hollow particles or a sol thereof are encapsulated by a matrix of a resin or other material, since only the apparent refractive index of the hollow particles is low, a film or layer with a low refractive index can be formed as a whole. As the hollow particles, those composed of SiO 2 or TiO 2 etc. are on the market. Also, as the matrix of the antireflection film, a curable resin or a silane compound that can be cured by the sol-gel method and has a low refractive index is suitable.

[0107] The functional film may be a reflective film that can reflect some light. Similar to the light absorption film 20, the reflective film has the function of shielding some light. By the cooperation of the light absorption film 20 and the reflective film, light of a predetermined wavelength can be shielded. The reflective film can be formed, for example, as a dielectric multilayer film. In this case, since the degree of freedom in designing the wavelength characteristics of the reflective film is high, the light shielding can be adjusted more finely. Also, since a part of the light to be shielded by the optical filter 1 can be shielded by the reflection function, the required absorbance of the light absorption film 20 can be reduced. As a result, the thickness of the light absorption film 20 can be reduced or the concentration of the light-absorbing compound contained in the light absorption film 20 can be reduced. The reflective film can be formed by forming a dielectric film on the main surface of the light absorption film 20 with an appropriate thickness. Examples of the dielectric are SiO 2 TiO 2 Ti 3 N 4 Al 2 O 3 and MgO. The reflective film may be a single-layer dielectric film or a multilayer dielectric film.

[0108] The functional film may be formed so as to cover a part of the surface of the frame 10 in addition to the surface of the light absorption film 20.

[0109] An imaging device provided with the optical filter 1 can be provided. As shown in FIG. 5, the imaging device 5 includes an imaging element 2, a lens 3, and the optical filter 1. The lens 3 transmits light from the subject and condenses it on the imaging element 2.

[0110] The optical filter 1 is disposed, for example, between the lens 3 and the imaging element 2 in the optical path of the light from the subject. The imaging element 2 is disposed, for example, on the circuit board 50. In the imaging device 5, for example, the main surface of the light absorption film 20 in the optical filter 1 and the light receiving surface of the imaging element 2 are separated and not in direct contact. For this reason, the difficulty level of the manufacturing process of the imaging device 5 is likely to be low, and the man-hours can be reduced or the manufacturing yield of the imaging device 5 can be improved.

Example

[0111] The present invention will be described in more detail by way of examples. It should be noted that the present invention is not limited to the following examples.

[0112] <Example 1> 4.500 g of copper acetate monohydrate and 240 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 1.646 g of Pliserf A208N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), which is a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain Solution A1. 40 g of THF was added to 0.706 g of phenylphosphonic acid and stirred for 30 minutes to obtain Solution B1α. 40 g of THF was added to 4.230 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain Solution B1β. Next, Solution B1α and Solution B1β were mixed and stirred for 1 minute, and 8.664 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.840 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.) were added to this mixed solution and stirred for another 1 minute to obtain Solution B1. While stirring Solution A1, Solution B1 was added to Solution A1 and stirred at room temperature for 1 minute. Next, 100 g of toluene was added to this solution and stirred at room temperature for 1 minute to obtain Solution C1. This Solution C1 was placed in a flask and subjected to solvent removal treatment using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model: N-1110SF) while heating with an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., model: OSB-2100). The set temperature of the oil bath was adjusted to 105°C. Thereafter, Solution D1 after solvent removal treatment was taken out from the flask. Thus, Solution D1, which is a liquid composition containing an arylphosphonic acid and a copper component, was obtained.

[0113] 1.800 g of copper acetate monohydrate and 100 g of THF were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 1.029 g of Prisurf A208N, which is a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain Solution E1. Also, 40 g of THF was added to 1.154 g of n-butylphosphonic acid and stirred for 30 minutes to obtain Solution F1. While stirring Solution E1, Solution F1 was added to Solution E1 and stirred at room temperature for 1 minute. Next, 30 g of toluene was added to this solution, and then stirred at room temperature for 1 minute to obtain Solution G1. This Solution G1 was placed in a flask and subjected to solvent removal treatment using a rotary evaporator while heating with an oil bath. The set temperature of the oil bath was adjusted to 105 °C. Thereafter, Solution H1 after solvent removal treatment was taken out from the flask. In this way, Solution H1, which is a liquid composition containing n-butylphosphonic acid and a copper component, was obtained.

[0114] 8.800 g of Solution D1, which is a liquid composition, Solution H1, 8.800 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.090 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 10.840 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 5.660 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 4.896 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain Solution J1, which is a light-absorbing composition.

[0115] 0.1 g of a surface antifouling coating agent (manufactured by Daikin Industries, Ltd., product name: Optool DSX, concentration of active ingredient: 20% by mass) and 19.9 g of a hydrofluoroether-containing liquid (manufactured by 3M, product name: Novec 7100) were mixed and stirred for 5 minutes to prepare a fluorine treatment agent (concentration of active ingredient: 0.1% by mass).

[0116] A borosilicate glass substrate (manufactured by SCHOTT, product name: D263 T eco) with dimensions of 136 mm × 108 mm × 0.70 mm was prepared. The above fluorine treatment agent was poured and applied onto one main surface of the glass substrate. Then, the glass substrate was left at room temperature for 24 hours to dry the coating film of the fluorine treatment agent, and then the glass surface was gently wiped with a dust-free cloth containing Novec 7100 to remove the excess fluorine treatment agent. In this way, a fluorine-treated substrate coated with a fluorine compound was produced.

[0117] Nine types of frames having the dimensions shown in Table 5 were prepared. In Table 5, each of A, B, a, b, t1, and t2 corresponds to the dimensions shown in FIGS. 1A and 1B. Frames α-1, α-2, and α-3 are frames made of MC nylon. The average linear expansion coefficient of MC nylon at 0°C to 60°C is 10.1×10 -5 [ / °C]. MC nylon is a registered trademark. Frames β-1, β-2, and β-3 are frames made of high-strength nylon. The average linear expansion coefficient of high-strength nylon at 0°C to 60°C is 12.5×10 -5 [ / °C]. Frames γ-1, γ-2, and γ-3 are frames made of PPS. The average linear expansion coefficient of PPS at 0°C to 60°C is 4.7×10 -5 [ / °C]. Each frame was placed on the fluorine-treated substrate. At this time, a part of the main surface of the fluorine-treated substrate was exposed through the through-holes of the frame.

[0118] The light-absorbing composition J1 solution was injected into the through-holes of each frame using a dispenser. Thereafter, it was dried in an environment at 45°C for 3 hours, and the temperature of the environment was gently raised to 85°C over 10 hours to volatilize the solvent contained in the J1 solution and promote the reaction of the components contained in the J1 solution, thereby curing the light-absorbing composition. Thereafter, the light-absorbing composition during curing was placed in an environment at 85°C and 85% relative humidity for 8 hours to complete the curing reaction. Thereby, the light-absorbing film according to Example 1 was formed so as to block the through-holes of the frame. The thickness of the light-absorbing film such that the optical properties such as the transmission spectrum of the light-absorbing film when the light-absorbing composition was completely cured became predetermined properties was determined in advance, and the injection amount of the light-absorbing composition was controlled so that the light-absorbing film had that thickness. Next, the frame with the light-absorbing film formed in the through-hole and the light-absorbing film were slowly peeled off from the fluorine-treated substrate. In this way, the optical filter according to Example 1 was obtained.

[0119] In the optical filter according to Example 1, since the thickness of the light-absorbing film was 207 μm, and t1 and t2 of the frame were 0.5 mm (500 μm) and 0.15 mm (150 μm), respectively, the ratios of the thickness of the light-absorbing film to t1 and t2 were 0.414 and 1.38, respectively.

[0120] <Example 2> An optical filter according to Example 2 was produced in the same manner as in Example 1, except that J2 solution prepared under the following conditions was used instead of J1 solution as the light-absorbing composition.

[0121] In the optical filter according to Example 2, the thickness of the light-absorbing film was 204 μm, and the ratios of the thickness of the light-absorbing film to t1 and t2 were 0.408 and 1.36, respectively.

[0122] D1 solution, H1 solution, 8.800 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.090 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 5.420 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 2.830 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 2.448 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain J2 solution, which is a light-absorbing composition.

[0123] <Example 3> As the light-absorbing composition, an optical filter according to Example 3 was produced in the same manner as in Example 1, except that J3 solution prepared under the following conditions was used instead of J1 solution.

[0124] In the optical filter according to Example 3, the thickness of the light-absorbing film was 195 μm, and the ratios of the thickness of the light-absorbing film to t1 and t2 were 0.390 and 1.30, respectively.

[0125] D1 solution, H1 solution, 8.800 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.090 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 2.710 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 1.415 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 1.224 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain J3 solution, which is a light-absorbing composition.

[0126] <Example 4> As the light-absorbing composition, an optical filter according to Example 4 was produced in the same manner as in Example 1, except that J4 solution prepared under the following conditions was used instead of J1 solution.

[0127] In the optical filter according to Example 4, the thickness of the light absorption film was 220 μm, and the ratios of the thickness of the light absorption film to t1 and t2 were 0.440 and 1.47, respectively.

[0128] 8.800 g of D1 solution, H1 solution, silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.090 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 9.756 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 5.732 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 5.957 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain J4 solution, which is a light-absorbing composition.

[0129] <Example 5> An optical filter according to Example 5 was produced in the same manner as in Example 1, except that J5 solution prepared under the following conditions was used instead of J1 solution as the light-absorbing composition.

[0130] In the optical filter according to Example 5, the thickness of the light absorption film was 218 μm, and the ratios of the thickness of the light absorption film to t1 and t2 were 0.436 and 1.45, respectively.

[0131] 4.500 g of copper acetate monohydrate and 240 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 6.000 g of Plisurf A219B (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain Solution A5. 40 g of THF was added to 0.710 g of phenylphosphonic acid and stirred for 30 minutes to obtain Solution B5α. 40 g of THF was added to 4.290 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain Solution B5β. Next, Solution B5α and Solution B5β were mixed and stirred for 1 minute, and 8.664 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.840 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.) were added to this mixed solution and stirred for another 1 minute to obtain Solution B5. While stirring Solution A5, Solution B5 was added to Solution A5 and stirred at room temperature for 1 minute. Next, 60 g of cyclopentanone was added to this solution, and then stirred at room temperature for 1 minute to obtain Solution C5. This Solution C5 was placed in a flask and subjected to solvent removal treatment using a rotary evaporator (manufactured by Tokyo Rika Kikai Co., Ltd., model: N-1110SF) while heating with an oil bath (manufactured by Tokyo Rika Kikai Co., Ltd., model: OSB-2100). The set temperature of the oil bath was adjusted to 105°C. Thereafter, the post-solvent removal Solution D5 was taken out from the flask. In this way, Solution D5, which is a liquid composition containing an arylphosphonic acid and a copper component, was obtained.

[0132] 7.040 g of Solution D5, silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.070 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 5.420 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 2.830 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 2.448 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain Solution J5, which is a light-absorbing composition.

[0133] <Example 6> As the light-absorbing composition, an optical filter according to Example 6 was produced in the same manner as in Example 1, except that J6 solution prepared under the following conditions was used instead of J1 solution.

[0134] In the optical filter according to Example 6, the thickness of the light-absorbing film was 220 μm, and the ratios of the thicknesses t1 and t2 of the light-absorbing film were 0.440 and 1.47, respectively.

[0135] 4.500 g of copper acetate monohydrate and 240 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours to obtain a copper acetate solution. Next, 3.000 g of Prysurf A212C (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is a phosphate ester compound, was added to the obtained copper acetate solution and stirred for 30 minutes to obtain A6 solution. 40 g of THF was added to 0.750 g of phenylphosphonic acid and stirred for 30 minutes to obtain B6α solution. 40 g of THF was added to 4.490 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain B6β solution. Next, B6α solution and B6β solution were mixed and stirred for 1 minute, and 8.664 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.840 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.) were added to this mixed solution, and further stirred for 1 minute to obtain B6 solution. While stirring A6 solution, B6 solution was added to A6 solution and stirred at room temperature for 1 minute. Next, 60 g of cyclopentanone was added to this solution, and then stirred at room temperature for 1 minute to obtain C6 solution. This C6 solution was placed in a flask and subjected to solvent removal treatment with a rotary evaporator (manufactured by Tokyo Rika Kikai Co., Ltd., model: N-1110SF) while heating with an oil bath (manufactured by Tokyo Rika Kikai Co., Ltd., model: OSB-2100). The set temperature of the oil bath was adjusted to 105°C. Thereafter, the D6 solution after the solvent removal treatment was taken out from the flask. Thus, D6 solution, which is a liquid composition containing an arylphosphonic acid and a copper component, was obtained.

[0136] D6 liquid, 7.040 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.070 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 5.420 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 2.830 g of tetraethoxysilane (TEOS) (special grade manufactured by Kishida Chemical Co., Ltd.), and 2.448 g of dimethyldiethoxysilane (DMDES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes to obtain J6 liquid, which is a light-absorbing composition.

[0137] <Comparative Example 1> As the light-absorbing composition, an optical filter according to Comparative Example 1 was produced in the same manner as in Example 1, except that J7 liquid prepared under the following conditions was used instead of J1 liquid.

[0138] In the optical filter according to Comparative Example 1, the thickness of the light-absorbing film was 201 μm, and the ratios of the thickness of the light-absorbing film to t1 and t2 were 0.402 and 1.34, respectively.

[0139] D1 liquid, H1 liquid, 8.800 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), and 0.090 g of aluminum alkoxide compound (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC) were added and stirred for 30 minutes to obtain J7 liquid, which is a light-absorbing composition.

[0140] Table 1 and Table 2 show each compound and its addition amount when preparing the light-absorbing compositions according to Examples 1 to 6 and Comparative Example 1. As shown in these tables, toluene was used as the solvent in Examples 1 to 4. On the other hand, cyclopentanone was used as the solvent in Examples 5 and 6. Since it is necessary to prevent the aggregation of the coating liquid when changing the solvent, it was necessary to change the type of phosphate ester as the dispersant according to the type of the solvent. For this reason, in Examples 5 and 6, a phosphate ester different from the phosphate ester used in Examples 1 to 4 was used. It is understood that it is desirable to select the solvent and the phosphate ester corresponding to the solvent according to the chemical resistance of the frame used for the optical filter.

[0141] When preparing the light-absorbing compositions according to Examples 1 to 6 and Comparative Example 1, Table 3 shows the alkoxysilane, its total addition amount, the solid content assuming that the alkoxysilane is completely hydrolyzed and polycondensed, and their ratios.

[0142] <Measurement of Transmission Spectrum and Thickness of Light-Absorbing Film> Regarding the light-absorbing films in the optical filters according to Examples 1 to 6 and Comparative Example 1, the transmission spectrum at an incident angle of 0° was measured using a UV-visible near-infrared spectrophotometer V-670 manufactured by JASCO Corporation. The thickness of the light-absorbing film in each optical filter was measured using a laser displacement meter LK-H008 manufactured by KEYENCE Corporation. Among the optical filters according to each Example and Comparative Example 1, the thickness of the light-absorbing film in the optical filter provided with frame α-1 was measured as a representative. The transmission spectra of the optical filters according to Examples 1 to 6 and Comparative Example 1 are shown in FIGS. 6 to 12, respectively. In addition, the transmission characteristics read from these transmission spectra are shown in Table 4. Moreover, the thickness of the light-absorbing film in each optical filter is shown in Table 4.

[0143] <Heat Cycle Test> Regarding the optical filters according to Examples 1 to 6 and Comparative Example 1, five samples were selected for each type of frame. A heat cycle test of 144 cycles was performed on the selected five samples. Each cycle included a period of 30 minutes at 85°C and 30 minutes at -40°C. In each cycle, the time required for heating and cooling was 5 minutes. A thermal shock tester TSA-103ES manufactured by ESPEC Corporation was used for the heat cycle test. When there was cracking or peeling in only one of the five samples, it was evaluated as "B", and when there was cracking or peeling in two or more samples, it was evaluated as "C". Those without cracking or peeling in all of the five samples were evaluated as "A". The results are shown in Table 6.

[0144] <Young's Modulus and Hardness> Using the Nano Indenter XP manufactured by MTS Systems Corporation, measurements were performed on the surface of the light absorption film of each optical filter according to the nanoindentation method (continuous stiffness measurement method). As the indenter, a diamond pyramid indenter was used, and the measurements were carried out at room temperature of about 23 °C and in the atmosphere. The average value of the hardness of the surface of each optical filter was determined by averaging the hardness values in the range of indentation depths of 5 to 10 μm in the hardness-indentation depth diagram obtained from this measurement. Also, the average value of the Young's modulus of each light absorption film was determined by averaging the Young's modulus values in the range of indentation depths of 5 to 10 μm in the Young's modulus-indentation depth diagram obtained from this measurement method. In addition, considering that the main component of the light absorption film is silicone resin, the Poisson's ratio of the light absorption film was set to 0.4. The results are shown in Table 4.

[0145] <Glass transition point> Regarding the light absorption film according to Example 1, dynamic viscoelasticity measurement (DMA) by the forced vibration tensile method was performed. For this measurement, the Rheovibron DDV-01FP manufactured by Orientec was used, and the measurement was carried out under the following conditions. Test method: Forced vibration tensile method (temperature sweep) Measurement temperature: -40 °C to 95 °C Temperature rising rate: 2 °C / min Vibration frequency: 1 Hz Distance between chucks: 30 mm Vibration amplitude: 10 μm Preload: 4.9 mN

[0146] From the results of DMA, the temperature dependencies of the storage modulus E’ and the loss modulus E” were determined for the light absorption film according to Example 1. The results are shown in Fig. 13. The temperature at which the storage modulus E’ decreased was 50.8 °C, and this temperature indicates the temperature at which the hardness began to decrease. The loss modulus E” indicates the energy loss caused by the microscopic Brownian motion accompanying the transition, and the peak temperature thereof was 55.4 °C. From these results, it was found that the glass transition point of the light absorption film according to Example 1 was in the range of 50 to 60 °C. The fact that the glass transition point is in such a temperature range is effective because it can prevent film cracking due to thermal expansion or contraction when the optical filter is exposed to high temperatures or subjected to thermal cycling, by the increased flexibility accompanying the state change of the light absorption film. The glass transition point of the light absorption film is desirably in the range of room temperature to 80 °C, more desirably in the range of 35 °C to 70 °C, and even more desirably in the range of 40 °C to 60 °C.

[0147] As shown in Table 4, the average Young's modulus of the light absorption films in the optical filters according to Examples 1 to 6 was 0.56 GPa to 2.0 GPa. On the other hand, the average Young's modulus of the light absorption film in the optical filter according to Comparative Example 1 was 2.6 GPa. From these results, it was suggested that the light absorption films of the optical filters of Examples 1 to 6 had the desired flexibility, but the flexibility of the light absorption film of the optical filter of Comparative Example 1 was inferior. According to the comparison between Examples 1 to 6 and Comparative Example 1, it is understood that the desired flexibility is easily imparted by adding a specific alkoxysilane to the light-absorbing composition. For example, as the addition amount of DMDES increases, the flexibility of the light absorption film tends to increase. The addition amount of DMDES is preferably 10% or more of the total solid content of the alkoxysilane on a mass basis in terms of solid content, and it is understood that the flexibility of the light absorption film can be improved by increasing the ratio in the range of 10 to 24%. On the other hand, in the light absorption film of each optical filter, the addition amount of TEOS is about 20% of the total solid content of the alkoxysilane on a mass basis in terms of solid content. While TEOS gives strength to the light absorption film, an increase in the ratio of TEOS in the light absorption film may cause cracks or fractures during or after the production process of the light absorption film. Therefore, the addition amount of TEOS is desirably 50% or less of the total solid content of the alkoxysilane on a mass basis in terms of solid content, and more desirably 35% or less. It is also possible to improve the flexibility by increasing the addition amount of the phosphate ester, which is a component other than the silane monomer. The content of the phosphate ester in the light absorption film of the optical filters according to Examples 5 and 6 is larger than the content of the phosphate ester in the light absorption film of the optical filters according to Examples 1 to 4. This is understood to be one of the reasons for the decrease in the Young's modulus of the light absorption film.

[0148] As shown in Table 5, it was confirmed that peeling or cracking of the light absorption film occurred in some samples. The optical filters according to Examples 1 to 6 showed good results in the heat cycle test. On the other hand, problems such as peeling or cracking of the light absorption film occurred in the heat cycle test of the optical filter according to Comparative Example 1. The light-absorbing composition for the light absorption film of the optical filters according to Examples 1 to 6 contained DMDES in which two organic functional groups were bonded to one silicon atom, so it was estimated that the thermal expansion coefficient of the light absorption film was relatively large. However, since it has flexibility to exhibit durability against distortion based on the difference between the thermal expansion coefficient of the frame and the thermal expansion coefficient of the light absorption film, it is considered that good results were shown in the heat cycle test. On the other hand, for Comparative Example 1, although it is estimated to have a higher Young's modulus and greater rigidity, it is considered that the durability against distortion caused by temperature change was insufficient.

[0149] It is considered that cracking and peeling of the light absorption film can be prevented by bringing the thermal expansion coefficient of the frame closer to the thermal expansion coefficient of the light absorption film. However, it was found that when the periphery of the light absorption film is completely fixed to the frame, it is necessary to adjust the properties of the light absorption film rather than adjusting the difference between the thermal expansion coefficient of the frame and the thermal expansion coefficient of the light absorption film. This is suggested by the fact that in the heat cycle test of optical filters using three types of frames having different expansion coefficients, almost no influence of the type of frame on the test results was shown.

[0150] According to the results regarding the optical filters according to the examples, it is understood that controlling the average value of the Young's modulus of the light absorption film to 0.56 GPa to 2.0 GPa is particularly effective from the viewpoint of realizing high resistance to temperature change. In addition, it is understood that using a frame made of a material having an average linear expansion coefficient of 4.7×10 -5 ~12.5×10 -5 [ / °C] is particularly important for obtaining an optical filter having high resistance to temperature change.

[0151]

Table 1

[0152]

Table 2

[0153]

Table 3

[0154]

Table 4

[0155]

Table 5

[0156]

Table 6

Claims

1. A frame having a through hole; a light absorbing film that is disposed so as to cover the through hole and contains a light absorbing compound; The average Young's modulus of the light-absorbing film measured according to a continuous stiffness measurement method is 2.5 GPa or less; Optical filters.

2. The average linear expansion coefficient of the material constituting the frame at 0°C to 60°C is 0.2 x 10 -5 [ / ℃] ~ 25 x 10 -5 2. The optical filter according to claim 1, wherein the temperature is 100° C. or more.

3. The optical filter according to claim 1 , wherein the frame is in contact with the through hole and has a first surface formed along a plane parallel to a main surface of the light absorbing film.

4. 4. The optical filter according to claim 1, wherein the light absorbing film has a thickness smaller than a dimension of the frame in a thickness direction of the light absorbing film.

5. 5. The optical filter according to claim 1, wherein the light absorbing film has a first main surface formed between one end and the other end of the frame in a thickness direction of the light absorbing film.

6. 6. The optical filter according to claim 1, wherein the light absorbing film has a second main surface formed so as to be flush with one end of the frame in a thickness direction of the light absorbing film.

7. 7. The optical filter according to claim 1, wherein the through hole includes at least one of a convex portion and a concave portion inside.

8. The optical filter according to claim 7 , wherein the light absorbing film is in contact with at least a part of the convex portion or at least a part of the concave portion in a thickness direction of the light absorbing film.

9. 9. The optical filter according to claim 7, wherein the light absorbing film is in contact with at least two of the surfaces constituting the convex portion or the concave portion inside the through hole.

10. the frame is a flat plate having a first end surface and a second end surface as main surfaces, and has a through hole drilled in a thickness direction of the frame; The through hole includes a protrusion protruding toward the inside of the through hole, the protrusion includes a first surface that is substantially parallel to one of the first end surface and the second end surface, the light absorbing film has a first major surface and a second major surface; the second main surface is flatly connected to one of the first end surface and the second end surface, When a length in a thickness direction of the frame between the first surface and any one of the first end surface and the second end surface that is flatly connected to the second main surface of the light absorbing film is t2, a ratio of the thickness of the light absorbing film to the t2 is greater than 1 and less than or equal to 2.

3. The optical filter according to claim 1 or 2.

11. The optical filter according to any one of claims 1 to 10, wherein the light absorbing film has a transmission spectrum that satisfies the following requirements (I), (II), (III), (IV), (V), (VI), and (VII): (I) There is a first cutoff wavelength showing a transmittance of 50% in the wavelength range of 380 nm to 440 nm. (II) There is a second cutoff wavelength showing a transmittance of 50% in the wavelength range of 600 nm to 720 nm. (III) The maximum transmittance in the wavelength range of 300 nm to 350 nm is 1% or less. (IV) The average transmittance in the wavelength range of 450 nm to 600 nm is 75% or more. (V) The maximum transmittance in the wavelength range of 750 nm to 1000 nm is 5% or less. (VI) The maximum transmittance in the wavelength range of 800 nm to 950 nm is 4% or less. (VII) The transmittance at a wavelength of 1,100 nm is 20% or less.

12. The optical filter according to any one of claims 1 to 11, wherein the light absorbing film has a thickness of 1 µm to 1000 µm.

13. An imaging element; a lens that transmits light from a subject and collects the light on the image sensor; The optical filter according to any one of claims 1 to 12, Imaging device.

14. supplying a light absorbing composition containing a light absorbing compound to fill a through hole of a frame having a through hole; and curing the light absorbing composition to form a light absorbing film. The average Young's modulus of the light-absorbing film measured according to a continuous stiffness measurement method is 2.5 GPa or less; A method for manufacturing an optical filter.

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