Optical filter, light-absorbing composition, method for manufacturing an optical filter, imaging device, sensing device, and sensing method

Abstract

An optical filter 1a comprises a light absorbing compound and a resin that contains the light absorbing compound. The optical filter 1a has a first transmittance spectrum that satisfies the conditions (i), (ii), (iii) and (iv) described below. The absolute value |λ1-UV 25°C - λ2-UV 25°C| is 8 nm or less. (i) The average of the transmittances within the wavelength range of 300 nm to 380 nm is 1% or less. (ii) The average of the transmittances within the wavelength range of 450 nm to 600 nm is 80% or more. (iii) The average of the transmittances within the wavelength range of 700 nm to 725 nm is 10% or less. (iv) The average of the transmittances within the wavelength range of 950 nm to 1,150 nm is 5% or less.

Description

Optical filter, light-absorbing composition, method for manufacturing an optical filter, sensing device, and sensing method

[0001] The present invention relates to an optical filter, a light-absorbing composition, a method for producing an optical filter, a sensing device, and a sensing method.

[0002] In imaging devices using solid-state imaging elements such as CCDs (Charge Coupled Devices) or CMOSs ​​(Complementary Metal Oxide Semiconductors), various optical filters are placed in front of the solid-state imaging elements to obtain images with good color reproducibility. Solid-state imaging elements generally have spectral sensitivity over a wide wavelength range, from the ultraviolet to the infrared. Meanwhile, human visual sensitivity is limited to the visible light range. Therefore, a known technique involves placing an optical filter in front of the solid-state imaging element to block part of the infrared or ultraviolet light, in order to bring the spectral sensitivity of the solid-state imaging element in an imaging device closer to the human visual sensitivity.

[0003] Conventionally, such optical filters have typically utilized light reflection by a dielectric multilayer film to block infrared or ultraviolet light. Meanwhile, in recent years, optical filters equipped with a film containing a light-absorbing agent have been attracting attention. Because the transmittance characteristics of optical filters equipped with a film containing a light-absorbing agent are less affected by the angle of incidence, even when light is incident obliquely on the optical filter in an imaging device, they can produce good images with little color change and little in-plane color unevenness, with good reproducibility. Furthermore, light-absorbing optical filters that do not use a light-reflecting film can suppress the occurrence of ghosts and flares caused by multiple reflections by the light-reflecting film, making it easier to obtain good images in backlit conditions or when photographing night scenes. Additionally, optical filters equipped with a layer containing a light-absorbing agent are advantageous in terms of miniaturizing and thinning imaging devices.

[0004] Known examples of such optical filters include optical filters having a layer containing a light absorber formed from phosphonic acid and copper ions. For example, Patent Document 1 describes an optical filter having a UV-IR absorbing layer capable of absorbing infrared and ultraviolet rays. The UV-IR absorbing layer contains a UV-IR absorber formed from phosphonic acid and copper ions. The UV-IR absorbing composition contains, for example, a phenyl-based phosphonic acid and an alkyl-based phosphonic acid so that the optical filter has predetermined optical properties.

[0005] Furthermore, Patent Document 2 describes an optical filter having a light absorbing layer containing copper phosphonate and an organic dye.

[0006] Patent No. 6232161 Patent No. 6709885

[0007] The techniques described in Patent Documents 1 and 2 have room for reexamination from the viewpoint of increasing the yield of products equipped with optical filters. Therefore, the present invention provides an optical filter that is advantageous from the viewpoint of increasing the yield of products equipped with optical filters.

[0008] The present invention provides an optical filter, the optical filter comprising: a light-absorbing compound; and a resin containing the light-absorbing compound; the optical filter has a first transmission spectrum at 25°C and an incident angle of 0° before a heating test in which the optical filter is heated at 125°C for 200 hours, the first transmission spectrum satisfying the following conditions (i), (ii), (iii), and (iv); the optical filter has a second transmission spectrum at 25°C and an incident angle of 0° after the heating test; and a wavelength λ at which a transmittance of 50% is achieved within a wavelength range of 350 nm to 450 nm in the first transmission spectrum. 1-UV 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 350 nm to 450 nm in the second transmission spectrum. 2-UV 25℃The present invention provides an optical filter in which the absolute value of the difference between the transmittance and the transmittance is 8 nm or less. (i) The average transmittance at wavelengths of 300 nm to 380 nm is 1% or less. (ii) The average transmittance at wavelengths of 450 nm to 600 nm is 80% or more. (iii) The average transmittance at wavelengths of 700 nm to 725 nm is 10% or less. (iv) The average transmittance at wavelengths of 950 nm to 1150 nm is 5% or less.

[0009] The present invention also provides a light-absorbing composition comprising: a light-absorbing compound; a curable resin; at least one selected from the group consisting of alkoxysilanes and alkoxysilane hydrolysates; and water.

[0010] The present invention also provides a method for producing an optical filter, comprising curing the curable resin of the light-absorbing composition by heating the composition through the following steps (a), (b), (c), and (d): (a) heating for 2 hours or more at a first heating temperature within a temperature range of room temperature to 60°C, (b) heating for 2 hours or more at a second heating temperature within a temperature range of the first heating temperature to 100°C, (c) heating for 2 hours or more at a third heating temperature within a temperature range of the second heating temperature to 140°C, and (d) heating for 1 hour or more at a fourth heating temperature within a temperature range of the third heating temperature to 200°C.

[0011] The present invention also provides an imaging device including the above optical filter.

[0012] The present invention also provides a sensing device comprising: an imaging device; and a computer connected to the imaging device, wherein the imaging device comprises the optical filter described above.

[0013] The present invention also provides a sensing method, which includes executing predetermined processing by a computer on image data obtained by an imaging device, wherein the imaging device is equipped with the optical filter described above.

[0014] The above optical filter is advantageous in terms of increasing the yield of products equipped with the optical filter.

[0015] FIG. 1A is a cross-sectional view showing an example of an optical film according to the present invention. FIG. 1B is a cross-sectional view showing another example of an optical film according to the present invention. FIG. 1C is a cross-sectional view showing yet another example of an optical film according to the present invention. FIG. 1D is a cross-sectional view showing yet another example of an optical film according to the present invention. FIG. 2A is a cross-sectional view schematically showing an example of an imaging device according to the present invention. FIG. 2B is a cross-sectional view schematically showing another example of an imaging device according to the present invention. FIG. 3 is a diagram schematically showing an automobile equipped with an imaging device according to the present invention. FIG. 4 is a block diagram showing an example of a sensing device according to the present invention. FIG. 5 is a graph showing the transmission spectrum of an optical filter according to Example 1. FIG. 6 is a graph showing the transmission spectrum of an optical filter according to Example 4. FIG. 7 is a graph showing the transmission spectrum of an optical filter according to Example 5. FIG. 8 is a graph showing the transmission spectrum of the optical filter according to Example 1 at an incident angle of 0° at 25° C. and 70° C. FIG. 9 is a graph showing the reflection spectrum of the optical filter according to Example 1. FIG. 10 is a graph showing the reflection spectrum of the optical filter according to Example 4. FIG. 11 is a graph showing the reflection spectrum of the optical filter according to Example 5. Fig. 12 is a graph showing the transmission spectra before and after a heating test of the optical filter according to Example 1. Fig. 13 is a graph showing the transmission spectra before and after a heating test of the optical filter according to Example 4. Fig. 14 is a graph showing the transmission spectra before and after a heating test of the optical filter according to Comparative Example 2. Fig. 15 is a graph showing the transmission spectra before and after a heating test of the optical filter according to Comparative Example 3.

[0016] When an optical filter, which blocks a portion of incident light, is placed in a specific environment, the yield of products equipped with the optical filter may decrease. For example, when a screening test involving heating is performed on an optical system component such as an optical filter or a product equipped with the optical filter, the yield of the product equipped with the optical filter may decrease depending on the conditions of the screening test, such as the heating conditions. Here, the screening test is not limited to a specific test. For example, the screening test may be a test performed at the time of designing a product equipped with an optical filter to confirm whether the optical filter has the required heat resistance. The screening test may be a test performed to screen out optical filters with initial failures or potential defects before shipping the optical filter. The screening test may be a test performed before introducing the optical filter into a manufacturing process for a product equipped with the optical filter to screen out products with initial failures or potential defects before shipping the product equipped with the optical filter. The screening test includes an inspection procedure in which a product is judged to be conforming or non-conforming, passed or failed, or passed or defective based on predetermined criteria. The type and conditions of the screening test are determined appropriately depending on the required durability or heat resistance. Furthermore, due to the nature of manufacturing, it is desirable that the screening test be completed in a short time and a judgment be made. The screening test may be, for example, a thermal cycle test conducted under conditions of an upper temperature of 60°C to 120°C and a lower temperature of -40°C to 5°C, or a heat shock test (thermal shock test) involving a sudden temperature change. Furthermore, from the perspective of whether a product has a predetermined heat resistance, the screening test may be a heating test. The heating test conditions may be, for example, a maintenance time of an upper temperature of 80°C to 200°C for 5 minutes to several hours. It is desirable that a judgment of conformance or non-conformance be made by a heating test under such conditions.For example, when the optical filter is to be mounted on an electronic substrate, the upper limit temperature for the heating test can be determined taking into consideration the upper limit temperature (e.g., 260° C.) of soldering used in manufacturing the electronic substrate. The heating test may be performed by placing the optical filter to be tested in a thermostatic chamber at room temperature, raising the temperature inside the thermostatic chamber to a target temperature such as 125° C., and maintaining the target temperature for a predetermined time (e.g., 200 hours), and then lowering the temperature to room temperature.

[0017] An example of a product equipped with an optical filter is an imaging device such as an onboard camera. Onboard cameras are mounted on vehicles such as automobiles and trains. The onboard cameras capture images of the vehicle's surroundings, such as traffic conditions, the presence or absence of obstacles, and clearance with other vehicles, or the interior of the vehicle. Images captured using onboard cameras are used for purposes such as displaying images on displays inside or outside the vehicle, recording images in a storage device, inputting the images into a computer for image sensing, image analysis, and data processing and utilization. Automobiles are also expected to be used in relatively hot regions, such as the Middle East. Additionally, the temperature inside a vehicle can become significantly higher under the blazing sun. For this reason, heat resistance is required for each component of onboard cameras mounted on vehicles such as automobiles. Therefore, optical filters used in onboard cameras may undergo screening tests before being installed in modules, etc. Onboard cameras also include cameras intended to be brought into the vehicle and used therein. Screening tests may include exposure to high-temperature environments or accelerated testing to ensure the heat resistance of the optical filters. In an in-vehicle camera, only parts that pass such heat resistance tests are considered to be conforming products (good products) and can be incorporated into a camera module, etc. On the other hand, parts such as optical filters that do not pass the required heat resistance tests are removed from the assembly process and disposed of as non-conforming, defective, or rejected products. Therefore, if there are a large number of non-conforming, defective, or rejected products, the yield rate for screening tests for the heat resistance of optical filters or inspections to determine whether heat resistance is met will be low, increasing manufacturing costs and directly leading to a decline in profits. Therefore, there is a strong trend toward optical filters that have heat resistance performance that exceeds thresholds or standards.

[0018] The present inventors have conducted extensive research to provide an optical filter having sufficient heat resistance, and further to increase the yield of products equipped with the optical filter, such as in-vehicle cameras. As a result of extensive trial and error, they have discovered that a specific optical filter utilizing light absorption has a specific heat resistance and is advantageous from the viewpoint of increasing the yield of products, and have thus completed the present invention.

[0019] Hereinafter, embodiments of the present invention will be described. Note that the following description is for illustrative purposes only and the present invention is not limited to the following embodiments.

[0020] FIG. 1A is a cross-sectional view showing an optical filter 1a. The optical filter 1a includes a light-absorbing compound and a resin containing the light-absorbing compound. The optical filter 1a absorbs light in a predetermined wavelength range. When light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at an incident angle of 0° at 25°C, the optical filter 1a has a first transmission spectrum that satisfies the following conditions (i), (ii), (iii), and (iv). This allows light belonging to a portion of the ultraviolet and infrared ranges to be blocked, and, for example, an imaging device equipped with the optical filter 1a can obtain an image using light generally belonging to the visible light range. The first transmission spectrum is a transmission spectrum obtained by measuring the optical filter 1a before a heating test in which the optical filter 1a is heated at 125°C for 200 hours. (i) The average transmittance at wavelengths of 300 nm to 380 nm is 1% or less. (ii) The average transmittance at wavelengths of 450 nm to 600 nm is 80% or more. (iii) The average transmittance in the wavelength range of 700 nm to 725 nm is 10% or less, and (iv) The average transmittance in the wavelength range of 950 nm to 1150 nm is 5% or less.

[0021] Regarding condition (i), the average transmittance in the wavelength range of 300 nm to 380 nm of the first transmission spectrum is preferably 0.8% or less, more preferably 0.6% or less, even more preferably 0.4% or less, and particularly preferably 0.2% or less. Light with wavelengths of 300 nm to 380 nm belongs to the ultraviolet range. This light is difficult for the human eye to perceive, and it is advantageous, except in certain fields, for an optical filter to have low transmittance in this wavelength range and high blocking ability for light in this wavelength range.

[0022] Regarding condition (ii), the average transmittance in the wavelength range of 450 nm to 600 nm of the first transmission spectrum is preferably 82% or more, and more preferably 85% or more. This wavelength belongs to the visible light range (380 nm to 780 nm), and the sensitivity of the human eye to light in this wavelength range (luminosity) is relatively high. Therefore, the human eye can recognize the brightness of light in this wavelength range, so it is advantageous for an optical filter to have a high transmittance in this wavelength range.

[0023] Regarding condition (iii), the average transmittance in the wavelength range of 700 nm to 725 nm of the first transmission spectrum is preferably 8% or less, more preferably 6% or less, and even more preferably 4% or less. This wavelength corresponds to the wavelength that exhibits the color red. Since red is perceived as brighter by the human eye than other primary colors such as blue and green, it is advantageous for the optical filter to have low transmittance in this wavelength range.

[0024] With respect to condition (iv), the average transmittance of the first transmission spectrum in the wavelength range of 950 nm to 1150 nm is preferably 4% or less, more preferably 2% or less, and even more preferably 1% or less. Solid-state imaging elements, such as CMOS or CCD, used in imaging devices contain semiconductors such as silicon. Therefore, solid-state imaging elements can have a predetermined sensitivity in the wavelength range up to 1150 nm, which is invisible to the human eye. Therefore, it is advantageous for an optical filter to have a sufficiently low transmittance in this wavelength range.

[0025] The average value of the transmittance in the wavelength range of 900 nm to 950 nm of the first transmission spectrum is not limited to a specific value. This average value is, for example, 5% or less, preferably 3% or less, more preferably 1% or less, even more preferably 0.5% or less, and particularly preferably 0.1% or less. For example, in position sensing using a laser, light including wavelengths such as 905 nm and 940 nm is emitted as reference light. Light of such wavelengths can be reflected by a measurement object, and the reflected light can be received for sensing. Therefore, it is advantageous for the optical filter to have a sufficiently low transmittance within a range including the wavelength corresponding to the reference light.

[0026] After the heating test, the optical filter 1a has a second transmission spectrum when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at an incident angle of 0° at 25° C. 1-UV 25℃ and wavelength λ 2-UV 25℃ Absolute value of the difference between |λ 1-UV 25℃ -λ 2-UV 25℃ is, for example, 8 nm or less. 1-UV 25℃ is a wavelength in the first transmission spectrum at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm. 2-UV 25℃ is the wavelength at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm in the second transmission spectrum. 1-UV 25℃ -λ 2-UV 25℃By having | be 8 nm or less, the wavelength at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm is less likely to change before and after the heating test. Therefore, for example, even if a screening test involving heating is performed on the optical filter 1a, the yield of products equipped with the optical filter is less likely to decrease. The heating test may involve placing the optical filter 1a in a thermostatic bath at room temperature, raising the temperature inside the bath to 125°C, maintaining the temperature at 125°C for 200 hours, and then allowing the temperature to naturally decrease to room temperature. The temperature of the optical filter 1a may be increased by placing it inside a thermostatic bath previously maintained at 125°C. The temperature of the optical filter 1a may be decreased by maintaining the temperature inside the thermostatic bath at 125°C for 200 hours, removing the optical filter 1a from the thermostatic bath with its high internal temperature, and allowing the optical filter 1a to naturally decrease outside the thermostatic bath. It should be noted that these procedures may subject the optical filter 1a to thermal shock. During the heating test, the humidity inside the thermostatic chamber may be left as it is. Specifically, the humidity inside the thermostatic chamber may be similar to the humidity inside a room maintained at 40 to 60%. The humidity inside the thermostatic chamber during the heating test may be 40 to 60%. Furthermore, a heating test may be performed on optical filters currently on the market. As long as the gist of the present application is satisfied, it does not matter whether a similar or different heating test has been performed in the past. It is sufficient that the gist of the present application is satisfied when a heating test is performed again or for the first time on an optical filter currently on the market.

[0027] wavelength λ 1-UV 25℃ is not limited to a specific value as long as it falls within the wavelength range of 350 nm to 450 nm. 1-UV 25℃ is the wavelength corresponding to the lower limit of the wavelength range of light that the human eye can perceive. From the viewpoint of consistency or similarity with the human visual sensitivity characteristics, the wavelength λ 1-UV 25℃ It is advantageous for the wavelength λ to be within this range. 1-UV 25℃ is, for example, 390 nm to 450 nm, preferably 395 nm to 445 nm, and more preferably 400 nm to 440 nm.

[0028] Absolute value | λ 1-UV 25℃ -λ 2-UV 25℃ is preferably 7 nm or less, more preferably 6 nm or less, and even more preferably 5 nm or less.

[0029] In the optical filter 1a, the wavelength λ 1-IR 25℃ and wavelength λ 2-IR 25℃ Absolute value of the difference between |λ 1-IR 25℃ -λ 2-IR 25℃ | is not limited to a specific value. 1-IR 25℃ is a wavelength in the first transmission spectrum at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm. 2-IR 25℃ is the wavelength at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm in the second transmission spectrum. 1-IR 25℃ -λ 2-IR 25℃ is, for example, 5 nm or less. In this case, the wavelength at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm is unlikely to change before and after the heating test. Therefore, even if a screening test involving heating is performed on the optical filter 1a, the yield of products equipped with the optical filter is unlikely to decrease.

[0030] Absolute value | λ 1-IR 25℃ -λ 2-IR 25℃ is preferably 4 nm or less, and more preferably 3 nm or less.

[0031] wavelength λ 1-IR 25℃ is not limited to a specific value as long as it falls within the wavelength range of 600 nm to 700 nm. 1-IR 25℃ is the wavelength corresponding to the upper limit of the wavelength range of light that can be recognized by the human eye, and from the viewpoint of agreement or similarity with the human visual sensitivity characteristics, the wavelength λ 1-IR 25℃It is advantageous for the wavelength λ to be within this range. 1-IR 25℃ is, for example, 610 nm to 690 nm, preferably 615 nm to 685 nm, and more preferably 620 nm to 680 nm.

[0032] In the optical filter 1a, the wavelength λ 1-20 25℃ and wavelength λ 2-20 25℃ Absolute value of the difference between |λ 1-20 25℃ -λ 2-20 25℃ | is not limited to a specific value. 1-20 25℃ is a wavelength at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm in the first transmission spectrum. 2-20 25℃ is the wavelength at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm in the second transmission spectrum. 1-20 25℃ -λ 2-20 25℃ is, for example, 5 nm or less. In this case, the wavelength at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm is unlikely to change before and after the heating test. Therefore, even if a screening test involving heating is performed on the optical filter 1a, the yield of products equipped with the optical filter 1a is unlikely to decrease. Furthermore, at or near the wavelength at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm, the steepness of the transmission spectrum increases, so that the absolute value |λ 1-20 25℃ -λ 2-20 25℃ By setting | equal to or less than a specific value, fluctuations in the transmission spectrum are less noticeable.

[0033] Absolute value | λ 1-20 25℃ -λ 2-20 25℃ is preferably 4 nm or less, and more preferably 3 nm or less.

[0034] In the optical filter 1a, the average value T 1-450 25℃ and the average value T2-450 25℃ Absolute value of the difference between |T 1-450 25℃ -T 2-450 25℃ | is not limited to a specific value. 1-450 25℃ is the average value of the transmittance in the wavelength range of 400 nm to 450 nm of the first transmission spectrum. 2-450 25℃ is the average value of the transmittance in the wavelength range of 400 nm to 450 nm of the second transmission spectrum. 1-450 25℃ -T 2-450 25℃ is, for example, 8% or less. In this case, the average value of the transmittance in the wavelength range of 400 nm to 450 nm is unlikely to fluctuate before and after the heating test. Therefore, even if the optical filter 1a is subjected to a screening test that involves heating, the yield of products equipped with the optical filter 1a is unlikely to decrease.

[0035] Absolute value | T 1-450 25℃ -T 2-450 25℃ is preferably 7% or less, and more preferably 6% or less.

[0036] In the optical filter 1a, the average value T 1-VIS 25℃ and the average value T 2-VIS 25℃ Absolute value of the difference between |T 1-VIS 25℃ -T 2-VIS 25℃ | is not limited to a specific value. 1-VIS 25℃ is the average value of the transmittance in the wavelength range of 450 nm to 600 nm of the first transmission spectrum. 2-VIS 25℃ is the average value of the transmittance in the wavelength range of 450 nm to 600 nm of the second transmission spectrum. 1-VIS 25℃ -T 2-VIS 25℃is, for example, 3% or less. In this case, the average value of transmittance in the wavelength range of 450 nm to 600 nm is unlikely to fluctuate before and after the heating test, and the change in brightness of the image acquired through the optical filter 1a is perceived as small. Therefore, for example, even if the optical filter 1a is subjected to a screening test that involves heating, the yield of products equipped with the optical filter 1a is less likely to decrease.

[0037] Absolute value | T 1-VIS 25℃ -T 2-VIS 25℃ is preferably 2.5% or less, and more preferably 2% or less.

[0038] The second transmission spectrum may satisfy the conditions for the first transmission spectrum, such as the above conditions (i), (ii), (iii), and (iv). The above conditions (i), (ii), (iii), and (iv) require that the spectrum of the optical filter has good compatibility with human visual sensitivity. If the above conditions (i), (ii), (iii), and (iv) are satisfied even after the heating test, this indicates that the optical filter can maintain good compatibility even after the heating test, suggesting that the optical filter of the present invention has heat resistance and can maintain or improve good yield even after a screening test involving heating.

[0039] The reflection spectrum obtained when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at a temperature of 25°C at an angle of incidence of 5° is not limited to a specific spectrum. For example, when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at a temperature of 25°C at an angle of incidence of 5°, the optical filter 1a has a reflection spectrum that satisfies the following conditions (I) and (II). In this case, the optical filter 1a reduces reflection of a portion of light belonging to the visible light and infrared light ranges, making it less likely for ghosts and flares to occur in an imaging device equipped with the optical filter 1a. In addition, satisfying condition (I) is advantageous in reducing purple fringing, a type of purple color fringing that appears around the contours of a subject and is specific to this wavelength range. (I) The maximum reflectance at wavelengths of 300 nm to 400 nm is 8% or less. (II) The average reflectance at wavelengths of 800 nm to 1150 nm is 10% or less.

[0040] Regarding condition (I), the maximum value of the reflectance in the wavelength range of 300 nm to 400 nm in the above reflection spectrum is preferably 6% or less.

[0041] Regarding condition (II), the average value of the reflectance in the wavelength range of 800 nm to 1150 nm in the above reflection spectrum is preferably 8% or less, and more preferably 6% or less.

[0042] When an optical filter is mounted on a camera module or the like, light reflected from the optical filter may further reflect off the lens barrel, housing, or lens that make up the camera module before reaching the image sensor. When such internally reflected light reaches the image sensor, ghosts or flares may appear in the image, potentially reducing the image quality. Therefore, it is desirable for the optical filter to have low reflectivity. In the reflection spectrum obtained when light with wavelengths of 300 nm to 1200 nm is incident on the optical filter 1a at a temperature of 25°C and an incident angle of 5°, the maximum reflectance within the wavelength range of 450 nm to 600 nm is, for example, greater than the maximum reflectance within the wavelength range of 800 nm to 1150 nm. In this reflection spectrum, the difference between the maximum reflectance within the wavelength range of 450 nm to 600 nm and the maximum reflectance within the wavelength range of 800 nm to 1150 nm is, for example, 5% or less, preferably 4% or less.

[0043] It is desirable that images obtained by an imaging device equipped with an optical filter have reduced ghosting and flare, further reduced purple fringing, and reduced color unevenness within a single image, such as differences in color between the central and peripheral portions. On the light-receiving surface of an imaging element, light rays incident on the central portion and light rays incident on the peripheral portion, including the chief ray, cause differences in the angle of incidence of the incident light rays onto the optical filter. The angle of incidence of light rays incident on the central portion of the light-receiving surface of the imaging element is small, while the angle of incidence of light rays incident on the peripheral portion is large. Such differences in the angles of incidence of the incident light rays may result in differences in the transmission spectrum of the optical filter, resulting in differences in color. Therefore, it is advantageous for the difference in the transmission spectrum of the optical filter at different angles of incidence to be small. Therefore, the optical filter 1a desirably satisfies one or more of the following conditions (i') to (vi'): In the following conditions (i') to (vi'), the notation |A-B| means the absolute value of the difference between the value of A and the value of B.

[0044] In the transmission spectrum when light of wavelengths 300 nm to 1200 nm is incident on the optical filter 1a at an incident angle of 40° and 60° at a temperature of 25°C, the wavelengths at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm are respectively defined as λ 40 / UV 25℃ and λ 60 / UV 25℃ This transmission spectrum is obtained by measuring the optical filter 1a before the heating test. (i')|λ 40 / UV 25℃ -λ 1-UV 25℃ The value of |λ is 7 nm or less, preferably 5 nm or less. 60 / UV 25℃ -λ 1-UV 25℃ The value of | is 14 nm or less, and preferably 10 nm or less.

[0045] In the transmission spectrum when light of wavelengths 300 nm to 1200 nm is incident on the optical filter 1a at an incident angle of 40° and 60° at a temperature of 25°C, the wavelengths at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm are respectively defined as λ 40 / IR 25℃ and λ 60 / IR 25℃ This transmission spectrum is obtained by measuring the optical filter 1a before the heating test. (iii')|λ 40 / IR 25℃ -λ 1-IR 25℃ The value of |λ is 8 nm or less, preferably 6 nm or less. 60 / IR 25℃ -λ 1-IR 25℃ The value of | is 16 nm or less, preferably 12 nm or less.

[0046] In the transmission spectrum when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at an incident angle of 0°, 40°, and 60° at a temperature of 25°C, the wavelengths at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm are defined as λ 0 / 20 25℃ , λ 40 / 20 25℃ , and λ60 / 20 25℃ This transmission spectrum is obtained by measuring the optical filter 1a before the heating test. 0 / 20 25℃ is λ 1-20 25℃ (v')|λ 40 / 20 25℃ -λ 0 / 20 25℃ The value of |λ is 8 nm or less, preferably 6 nm or less. 60 / 20 25℃ -λ 0 / 20 25℃ The value of | is 16 nm or less, preferably 12 nm or less.

[0047] The optical filter 1a has a third transmission spectrum when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at an incident angle of 0° at 70°C. The third transmission spectrum is obtained by measuring the optical filter 1a before the heating test. The third transmission spectrum is not limited to a specific spectrum. In the optical filter 1a, 1-UV 25℃ and wavelength λ UV 70℃ Absolute value of the difference between |λ 1-UV 25℃ -λ UV 70℃ | is not limited to a specific value. UV 70℃ is the wavelength at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm in the third transmission spectrum. 1-UV 25℃ -λ UV 70℃ is, for example, 10 nm or less. In this case, even if the optical filter 1a is placed in an environment at room temperature or a relatively high temperature, the wavelength at which the transmittance is 50% within the wavelength range of 350 nm to 450 nm is unlikely to fluctuate, and a shift or deviation in the transmission spectrum is suppressed. Therefore, the optical filter 1a is likely to have a transmission spectrum with little temperature dependency and is likely to have the desired heat resistance.

[0048] Absolute value | λ 1-UV 25℃ -λ UV70℃ is preferably 9 nm or less, and more preferably 8 nm or less.

[0049] In the optical filter 1a, the wavelength λ 1-IR 25℃ and wavelength λ IR 70℃ Absolute value of the difference between |λ 1-IR 25℃ -λ IR 70℃ | is not limited to a specific value. IR 70℃ is the wavelength at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm in the third transmission spectrum. 1-IR 25℃ -λ IR 70℃ is, for example, 10 nm or less. In this case, even if the optical filter 1a is placed in an environment at room temperature or a relatively high temperature, the wavelength at which the transmittance is 50% within the wavelength range of 600 nm to 700 nm is unlikely to fluctuate, and a shift or deviation in the transmission spectrum is suppressed. Therefore, the optical filter 1a is likely to have a transmission spectrum with little temperature dependency and is likely to have the desired heat resistance.

[0050] In the optical filter 1a, the transmittance T 400 25℃ and transmittance T 400 70℃ Absolute value of the difference between |T 400 25℃ -T 400 70℃ | is not limited to a specific value. 400 25℃ is the transmittance at a wavelength of 400 nm in the first transmission spectrum. 400 70℃ is the transmittance at a wavelength of 400 nm in the third transmission spectrum. 400 25℃ -T 400 70℃| is, for example, 20% or less. In this case, even if the optical filter 1a is placed in an environment at room temperature or a relatively high temperature, the transmittance at a wavelength of 400 nm is unlikely to fluctuate, and a shift or deviation of the transmission spectrum is suppressed. Therefore, the optical filter 1a is likely to have a transmission spectrum with little temperature dependency and is likely to have the desired heat resistance. Furthermore, 400 nm < λ 1-UV 25℃ and / or 400 nm < λ UV 70℃ When this is the case, in the spectrum of the optical filter 1a, the wavelength of 400 nm belongs to a band where the transmittance increases rapidly from zero or close to zero, and therefore the temperature dependence of the transmission spectrum of the optical filter 1a can be further reduced.

[0051] Absolute value | T 400 25℃ -T 400 70℃ is preferably 19% or less, more preferably 18% or less, and even more preferably 17% or less.

[0052] As shown in FIG. 1A , the optical filter 1a is, for example, in the form of a film and contains a resin as its main component. In this specification, a main component refers to the component that is contained in the largest amount by mass. The thickness of the optical filter 1a is not limited to a specific value. The thickness is, for example, 65 μm to 600 μm, and preferably 90 μm to 300 μm. The thinner the optical filter 1a, the more it can contribute to a lower profile of the imaging device. On the other hand, by making the optical filter 1a thicker than a predetermined value, it is possible to prevent warping or wrinkling of the optical filter 1a during the manufacture of the imaging device, which would lead to a deterioration in image quality.

[0053] The haze (or haze value, cloudiness) of the optical filter 1a is not limited to a specific value. The optical filter 1a has a haze of, for example, 0.5% or less. The smaller the haze of the optical filter, the higher the transparency of the optical filter, which is suitable for improving the quality of images captured by an imaging device. For example, even if the optical filter has a spectrum with high transmittance in the visible light range, if the haze of the optical filter is high, light scattering occurs inside or on the surface of the optical filter, increasing the tendency for the optical filter to become cloudy or opaque. For this reason, it is important to evaluate the optical filter by its haze. The optical filter 1a preferably has a haze of 0.3% or less.

[0054] The optical filter 1a can be manufactured, for example, by curing a predetermined light-absorbing composition. The light-absorbing composition contains a light-absorbing compound, a curable resin, at least one selected from the group consisting of alkoxysilanes and alkoxysilane hydrolysates, and water. The light-absorbing compound absorbs a portion of light having a wavelength in the range of 300 nm to 380 nm and a portion of light having a wavelength in the range of 700 nm to 1200 nm. In the process of heating and curing such a light-absorbing composition, by raising the temperature relatively slowly from room temperature (15°C to 35°C), it is expected that the reaction will occur without evaporating excess water and without volatilizing the silane compound. The formation of —O—Si—O— bonds is promoted via the silanol groups of the hydrolyzed alkoxysilane, and a strong crosslinked structure can be formed in the optical filter 1a. By including a moderate amount of such strong crosslinked structures in the optical filter 1a, the desired heat resistance is likely to be achieved.

[0055] The water content in the light-absorbing composition is not limited to a specific value. The water content in the light-absorbing composition is, for example, 700 ppm (parts per million) to 7000 ppm by mass. In this case, water necessary for hydrolysis of alkoxysilane is supplied during curing of the light-absorbing composition, and a function of promoting condensation polymerization via silanol groups of the hydrolyzed alkoxysilane is expected.

[0056] The water content in the light-absorbing composition is preferably 1200 ppm or more, more preferably 3500 ppm or more. Furthermore, the water content in the light-absorbing composition is preferably 6600 ppm or less, and may be 5000 ppm or less, 4000 ppm or less, or less than 1000 ppm. The water content in the light-absorbing composition can be adjusted according to the heat resistance required for the optical filter 1a. The water content in the light-absorbing composition can be adjusted by adding water in preparing the light-absorbing composition. When a hydrate is used in preparing the light-absorbing composition, the water content may be adjusted taking into account the total amount of water added and the amount derived from the hydrate.

[0057] When the water content in the light-absorbing composition is 7000 ppm or less, the possibility of a water-related reaction rapidly progressing locally during curing of the light-absorbing composition is reduced, and the occurrence of aggregation or phase separation of the light-absorbing compound is likely to be suppressed, which in turn tends to suppress the formation of scatterers inside or on the surface of the optical filter 1a, the occurrence of cracks or fissures, and the increase in haze.

[0058] The method for producing the optical filter 1a by curing the light-absorbing composition is not limited to a specific method. For example, the light-absorbing composition is cured to form a curable resin through a process including the heating steps (a), (b), (c), and (d) below. This allows the optical filter 1a to be produced. The room temperature is, for example, 15°C to 35°C. This method makes it easy to achieve a desired balance between the evaporation of components such as water and silane compounds that accompanies heating and the promotion of the reaction in the curing of the light-absorbing composition. For example, excessive evaporation of water is suppressed, and the removal of by-products by evaporation and the reaction for curing are adjusted to a desired state. This prevents the curing reaction from being too fast, resulting in wrinkles in the optical filter and increased haze. (a) Heating for 2 hours or more at a first heating temperature within a temperature range of room temperature to 60°C; (b) Heating for 2 hours or more at a second heating temperature within a temperature range of the first heating temperature to 100°C; (c) Heating for 2 hours or more at a third heating temperature within a temperature range of the second heating temperature to 140°C; (d) Heating for 1 hour or more at a fourth heating temperature within a temperature range of the third heating temperature to 200°C.

[0059] In the production of the optical filter 1a, a so-called humidification treatment may be performed by exposing the composition to a relatively high humidity atmosphere for a certain period of time. The moisture in the atmosphere may promote hydrolysis of the alkoxysilane contained in the light-absorbing composition, thereby promoting the formation of —O—Si—O— bonds. Furthermore, the humidification treatment allows the production of a hard, dense optical filter 1a in a state in which the fine particles containing the light-absorbing agent do not aggregate.

[0060] The light-absorbing compound is not limited to a specific substance as long as it absorbs a portion of light in the wavelength range of 300 nm to 380 nm and a portion of light in the wavelength range of 700 nm to 1200 nm. The light-absorbing compound includes, for example, a phosphonic acid and a copper component.

[0061] The phosphonic acid in the light-absorbing compound is not limited to a specific phosphonic acid. The phosphonic acid may be represented, for example, by the following formula (a): In formula (a), R is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group has been substituted with a halogen atom. In this case, the transmission band of the optical filter 1a is likely to extend to a wavelength of around 700 nm, and the optical filter 1a is likely to have the desired transmittance characteristics.

[0062]

[0063] The phosphonic acid is, for example, methylphosphonic acid, ethylphosphonic acid, normal (n-)propylphosphonic acid, isopropylphosphonic acid, normal (n-)butylphosphonic acid, isobutylphosphonic acid, sec-butylphosphonic acid, tert-butylphosphonic acid, or bromomethylphosphonic acid.

[0064] The phosphonic acid in the light-absorbing compound may be represented by formula (a), where R1 is an aryl group or a halogenated aryl group in which at least one hydrogen atom in the aryl group has been substituted with a halogen atom. The aryl group is, for example, a phenyl group. The halogenated aryl group is, for example, a halogenated phenyl group. This makes it easier for the optical filter 1a to have the desired transmittance characteristics.

[0065] The copper component in the light-absorbing compound is a concept that includes copper ions, copper complexes, copper-containing compounds, and the like. The copper component can have desirable absorption characteristics for a portion of light in the near-infrared region and high light transmittance in the visible light region spanning wavelengths of 450 nm to 680 nm. Specifically, excellent near-infrared absorption characteristics are exhibited by selectively absorbing light of a wavelength in the near-infrared region corresponding to this energy through the transition of electrons in the d orbital of the divalent copper ion. In particular, the divalent copper ion may be mixed with phosphonic acid in the form of a copper salt, and the phosphonic acid may be coordinated to the copper ion to form a copper complex (copper salt).

[0066] The source of the copper component in the light-absorbing compound is not limited to a specific substance. The source of the copper component is, for example, a copper salt. The copper salt may be an anhydride or hydrate of copper chloride, copper formate, copper stearate, copper benzoate, copper pyrophosphate, copper naphthenate, or copper citrate. For example, copper acetate monohydrate is expressed as Cu(CH3COO)2·H2O, and one mole of copper acetate monohydrate provides one mole of copper ions. These copper salts may be used alone, or multiple copper salts or a mixture thereof may be used.

[0067] The contents of the copper component and the phosphonic acid in the light-absorbing composition are not limited to specific values. The ratio of the content of the phosphonic acid to the content of the copper component in the light-absorbing composition is, for example, 0.3 to 1.5 on a substance amount (molar) basis. The ratio of the content of the phosphonic acid to the content of the copper component in the light-absorbing composition may be desirably 0.4 to 1.4, more desirably 0.6 to 1.2, and even more desirably 0.8 to 1.1.

[0068] The light absorbing compound may be a compound containing a sulfonic acid and a copper component, or M n Cu y P.O. 4-z (M is a metal element other than Cu). x WO 4-y (wherein M is a metal element other than W), or an organic compound such as a phthalocyanine compound, a cyanine compound, a squarylium compound, or an azo compound.

[0069] The curable resin is not limited to a specific resin. For example, the curable resin is a resin capable of dispersing or dissolving a light-absorbing compound and retaining it. The curable resin is preferably liquid in an uncured or unreacted state and capable of dispersing or dissolving a light-absorbing compound. Furthermore, the curable resin can be applied to any object by a coating method such as spin coating, spraying, dipping, or dispensing to form a coating film. The object on which the coating film is formed is a substrate having any surface, whether flat or curved. The curable resin can be cured by heating, humidifying, irradiating with energy such as light, or a combination of these methods. The curable resin may satisfy at least one of the following conditions: the transmission spectrum of a plate-shaped object having a smooth surface and a thickness of 1 mm, formed by curing the curable resin, is 90% or more at wavelengths of 450 nm to 800 nm. Examples of curable resins include cyclic polyolefin resins, epoxy resins, polyimide resins, modified acrylic resins, silicone resins, and polyvinyl resins such as PVB.

[0070] The inclusion of at least one selected from the group consisting of alkoxysilanes and alkoxysilane hydrolysates in the light-absorbing composition prevents aggregation of particles of the light-absorbing compound. Therefore, the light-absorbing compound is well dispersed in the light-absorbing composition, and the light absorber is easily dispersed in the optical filter 1a. Therefore, by treating the light-absorbing composition so that the hydrolysis reaction and condensation polymerization reaction of the alkoxysilane occur sufficiently during curing, an —O—Si—O— bond is formed, and the optical filter 1a is likely to have good moisture resistance. In addition, the optical filter 1a is likely to have good heat resistance. This is because siloxane bonds have higher bond energy and are more chemically stable than bonds such as —C—C— and —C—O— bonds, and therefore have excellent heat resistance and moisture resistance.

[0071] The alkoxysilane is not limited to a specific alkoxysilane as long as it can form a hydrolysis-condensation polymerization compound having a siloxane bond in the optical filter 1 a through hydrolysis and condensation polymerization. The alkoxysilane may be, for example, a monomer such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, or 3-glycidoxypropylmethyldiethoxysilane, or may be a dimer or oligomer in which parts of these are bonded together.

[0072] The light-absorbing composition may further contain, for example, a phosphate ester compound. The phosphate ester compound facilitates good dispersion of the light-absorbing compound in the light-absorbing composition. The phosphate ester may function as a dispersant for the light-absorbing compound, or a portion of the phosphate ester may react with a metal component to form a compound. For example, the phosphate ester may coordinate with the light-absorbing compound or react with the compound, or may partially form a complex with the copper component. As long as the optical filter 1a satisfies the conditions regarding the predetermined transmission spectrum, the compound containing the phosphate ester and the copper component may also absorb light of some wavelengths. The phosphate ester may not be substantially present in the light-absorbing composition, which is the precursor of the optical filter 1a, as long as the light-absorbing substance containing at least a phosphonic acid and a copper component is suitably dispersed. Furthermore, when at least one selected from the group consisting of alkoxysilanes and alkoxysilane hydrolysates is contained in the light-absorbing composition to impart dispersion function, the amount of phosphate ester added can be reduced.

[0073] The phosphate ester is not limited to a specific phosphate ester or compound thereof. The phosphate ester may have, for example, a polyoxyalkyl group. Examples of such phosphate esters include Plysurf A208N: polyoxyethylene alkyl (C12, C13) ether phosphate ester, Plysurf A208F: polyoxyethylene alkyl (C8) ether phosphate ester, Plysurf A208B: polyoxyethylene lauryl ether phosphate ester, Plysurf A219B: polyoxyethylene lauryl ether phosphate ester, Plysurf AL: polyoxyethylene styrenated phenyl ether phosphate ester, Plysurf A212C: polyoxyethylene tridecyl ether phosphate ester, and Plysurf A215C: polyoxyethylene tridecyl ether phosphate ester. All of these are products manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Additionally, examples of phosphate esters include NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate ester, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate ester, and NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester, all of which are products manufactured by Nikko Chemicals Co., Ltd. These phosphate ester compounds may be used alone or in combination.

[0074] The contents of phosphonic acid and phosphate ester in the light-absorbing composition or optical filter 1a are not limited to specific values. The ratio of the phosphonic acid content to the phosphate ester content in the light-absorbing composition or optical filter 1a is, for example, 0.6 to 1.6 by mass. This suppresses hydrolysis of the phosphate ester even when the optical filter 1a comes into contact with water vapor, making the optical filter 1a more likely to have good weather resistance. The ratio of the phosphonic acid content to the phosphate ester content in the light-absorbing composition or optical filter 1a may desirably be 0.7 to 1.5, and more desirably be 0.8 to 1.4.

[0075] The ratio of the copper component content to the phosphorus component content in the light-absorbing composition or optical filter 1a is not limited to a specific value. The ratio of the copper component content to the phosphorus component content in the light-absorbing composition or optical filter 1a is, for example, 1.0 to 3.0, and preferably 1.5 to 2.0, on a mass basis. The phosphorus component may be derived from a phosphonic acid contained in the light-absorbing composition, or may be derived from a phosphonic acid and a phosphate ester contained in the light-absorbing composition, or may be contained in other additives.

[0076] The light-absorbing composition may contain a curing catalyst involved in curing the curable resin. The curing catalyst may be a catalyst that can control conditions such as the curing speed of the curable resin, the curing reactivity of the curable resin, and the hardness of the cured product of the curable resin.

[0077] The curing catalyst is preferably an organic compound containing a metal component (organometallic compound). The organometallic compound is not limited to a specific compound. Examples of the organometallic compound include an organoaluminum compound, an organotitanium compound, an organozirconium compound, an organozinc compound, and an organotin compound.

[0078] Examples of organic aluminum compounds include, but are not limited to, aluminum salt compounds such as aluminum triacetate and aluminum octylate, aluminum alkoxide compounds such as aluminum trimethoxide, aluminum triethoxide, aluminum dimethoxide, aluminum diethoxide, aluminum triallyl oxide, aluminum diallyl oxide, and aluminum isopropoxide, and aluminum methoxybis(ethylacetoacetate), aluminum methoxybis(acetylacetonate), aluminum ethoxybis(ethylacetoacetate), aluminum ethoxybis(acetylacetonate), and aluminum isopropoxybis(ethylacetoacetate). Examples of the aluminum chelate compounds include aluminum isopropoxybis(methyl acetoacetate), aluminum isopropoxybis(t-butyl acetoacetate), aluminum butoxybis(ethyl acetoacetate), aluminum dimethoxy(ethyl acetoacetate), aluminum dimethoxy(acetylacetonate), aluminum diethoxy(ethyl acetoacetate), aluminum diethoxy(acetylacetonate), aluminum diisopropoxy(ethyl acetoacetate), aluminum diisopropoxy(methyl acetoacetate), aluminum tris(ethyl acetoacetate), and aluminum tris(acetylacetonate). These may be used alone or in combination.

[0079] Examples of organic titanium compounds include, but are not limited to, titanium chelates such as titanium tetraacetylacetonate, dibutyloxytitanium diacetylacetonate, titanium ethylacetoacetate, titanium octylene glycolate, and titanium lactate, as well as titanium alkoxides such as tetraisopropyl titanate, tetrabutyl titanate, tetramethyl titanate, tetra(2-ethylhexyl titanate), titanium tetra-2-ethylhexoxide, titanium butoxy dimer, titanium tetra-normal butoxide, titanium tetraisopropoxide, and titanium diisopropoxybis(ethylacetoacetate). These may be used alone or in combination.

[0080] Examples of organic zirconium compounds include, but are not limited to, zirconium chelates such as zirconium tetraacetylacetonate, zirconium dibutoxybis(ethylacetoacetate), zirconium monobutoxyacetylacetonate bis(ethylacetoacetate), and zirconium tributoxymonoacetylacetonate, as well as zirconium alkoxides such as zirconium tetra-normal butoxide and zirconium tetra-normal propoxide. These may be used alone or in combination.

[0081] Examples of organic zinc compounds include zinc alkoxides such as dimethoxyzinc, diethoxyzinc, and ethylmethoxyzinc, which may be used alone or in combination.

[0082] Examples of organotin compounds include tin alkoxides such as dimethyltin oxide, diethyltin oxide, dipropyltin oxide, dibutyltin oxide, dipentyltin oxide, dihexyltin oxide, diheptyltin oxide, and dioctyltin oxide, which may be used alone or in combination.

[0083] The curing catalyst may further contain at least one selected from the group consisting of the alkoxides having the above-mentioned metal components and hydrolysates of alkoxides having the above-mentioned metal components. The alkoxides having the metal components and hydrolysates of alkoxides having the metal components are collectively referred to as "metal alkoxide compounds." Metal alkoxides are represented by the general formula M(OR) n(M is a metal element, n is an integer of 1 or greater), and is a compound in which the hydrogen atom of a hydroxy group of an alcohol is substituted with the metal element M. Metal alkoxides form M-OH upon hydrolysis, and further form an M-O-M bond upon reaction with metal alkoxides of other molecules. For example, when a flowable light-absorbing composition is cured to form the optical filter 1a, the metal alkoxide compound may function as a catalyst to promote curing of the light-absorbing composition. When the light-absorbing composition is cured by heat treatment, the higher the heat treatment temperature, the more likely it is that environmental resistance, such as heat resistance, will improve. On the other hand, if the heat treatment temperature is high, the properties of the light-absorbing compound may deteriorate. However, when the optical filter 1a contains a metal alkoxide compound, the curing of the light-absorbing composition can be promoted even if the heat treatment temperature is not high. As a result, the optical filter 1a is likely to have high environmental resistance.

[0084] The metal component contained in the metal alkoxide compound is not limited to a specific component, and examples of the metal component include Al, Ti, Zr, Zn, Sn, and Fe. Examples of metal alkoxides include CAT-AC and DX-9740, which are aluminum alkoxides manufactured by Shin-Etsu Chemical Co., Ltd., ORGATIXX AL-3001, which is an aluminum alkoxide manufactured by Matsumoto Fine Chemical Co., Ltd., aluminum isopropoxide, which is an aluminum alkoxide manufactured by Tokyo Chemical Industry Co., Ltd., titanium alkoxides D-20, D-25, and DX-175 manufactured by Shin-Etsu Chemical Co., Ltd., titanium alkoxides ORGATIXX TA-8, TA-21, TA-30, TA-80, and TA-90 manufactured by Matsumoto Fine Chemical Co., Ltd., zirconia alkoxides D-15 and D-31 manufactured by Shin-Etsu Chemical Co., Ltd., and zirconia alkoxides ORGATIXX ZA-45 and ZA-65 manufactured by Matsumoto Fine Chemical Co., Ltd. can be used.

[0085] The ratio of the copper content to the metal content contained in the metal alkoxide compound in the optical filter 1a is not limited to a specific value. The ratio of the copper content to the metal content contained in the metal alkoxide compound in the optical filter 1a is 1×10 2 ~7 x 102 may be, and preferably 2×10 2 ~6 x 10 2 and more preferably 3×10 2 ~5 x 10 2 may be.

[0086] Furthermore, the ratio of the content of the phosphorus component to the content of the metal component contained in the metal alkoxide compound in the optical filter 1a is not limited to a specific value. The ratio of the content of the phosphorus component to the content of the metal component contained in the metal alkoxide compound in the optical filter 1a is 0.5×10 on a mass basis. 2 ~5 x 10 2 may be, and preferably 1×10 2 ~4 x 10 2 and more preferably 1.5×10 2 ~3 x 10 2 may be.

[0087] The light-absorbing composition may contain an ultraviolet absorber that absorbs a portion of ultraviolet light. The ultraviolet absorber is not limited to a specific compound as long as the first transmission spectrum of the optical filter 1 a satisfies predetermined conditions.

[0088] The ultraviolet absorber is preferably selected from the viewpoints of absorbing light in a desired wavelength range, being compatible with a specific solvent, dispersing well in a light-absorbing composition, particularly a curable resin, and having excellent environmental resistance. Examples of ultraviolet absorbers include benzophenone-based compounds, benzotriazole-based compounds, salicylic acid-based compounds, and triazine-based compounds. For example, Tinuvin PS, Tinuvin 99-2, Tinuvin 234, Tinuvin 326, Tinuvin 329, Tinuvin 900, Tinuvin 928, Tinuvin 405, and Tinuvin 460 can be used as ultraviolet absorbers. These are ultraviolet absorbers manufactured by BASF, and Tinuvin is a registered trademark.

[0089] The content of the ultraviolet absorber in the optical filter 1a is not limited to a specific value as long as the first transmission spectrum of the optical filter 1a satisfies predetermined conditions. High absorption capacity can be achieved by including a small amount of ultraviolet absorber. The ratio of the content of the ultraviolet absorber to the content of the copper component in the optical filter 1a is, by mass, for example, 0.01 to 1, preferably 0.02 to 0.5, and more preferably 0.07 to 0.14. The ratio of the content of the ultraviolet absorber to the content of the phosphorus component in the light absorber 10 is, by mass, for example, 0.02 to 2, preferably 0.04 to 1, and more preferably 0.12 to 0.26.

[0090] For example, as shown in FIGS. 1B, 1C, and 1D, optical filtering articles 10a, 10b, and 10c each having an optical filter 1a can be provided.

[0091] As shown in FIG. 1B , the optical filter 1a may be disposed on a support 20. The support 20 is not limited to a specific support. The support 20 may be, for example, a transparent dielectric material such as glass or resin. For example, if the support 20 is rigid, the rigidity of an article including the optical filter 1a is increased, making it easier to handle the optical filter 1a during assembly of a product such as an imaging device, and reducing degradation in image quality. The support 20 may be plate-shaped or may be one or more lenses included in the lens system of the imaging device. The support 20 may have a planar or curved main surface. The support 20 may be an optical element (including an acousto-optical element) such as a mirror, a prism, a diffuser, a planar microlens array, a polarizer, a diffraction grating, a hologram, an optical modulation element, an optical deflection element, or a filter. The support 20 may be a light-transmitting shield such as a solid-state imaging device, a window or windshield of a building or an automobile, a helmet, or goggles. The support 20 may also be a display device such as a display or a screen.

[0092] As shown in FIG. 1C , when the optical filter 1a is plate-shaped, a predetermined functional film 31 or functional layer 32 may be formed on at least one major surface of the optical filter 1a. The functional film 31 or functional layer 32 is not limited to a specific film or layer. The functional film 31 or functional layer 32 may be a hard coating film (hard coat) or hard coating layer, a reflection-reducing film or layer, an anti-reflection film or layer, a reflective film or layer, a polarizing film or layer, or a selective wavelength light-absorbing film or layer. The hard coating film or layer is a film or layer intended to improve scratch resistance. The reflection-reducing film or layer, or the anti-reflection film or layer is a film or layer intended to reduce or prevent the generation of reflected light belonging to a specific wavelength range from the surface of the optical filter 1a when light is incident on the optical filter 1a. Hereinafter, in this specification, reflection-reducing films and anti-reflection films are collectively referred to as "anti-reflection films." The reflective film or reflective layer is a film or layer that reflects light belonging to a specific wavelength range from its surface more strongly when light is incident toward the optical filter 1a. The polarizing film or polarizing layer is a film or layer that reduces the transmittance of light having a polarization direction other than a specific direction when light is incident toward the optical filter 1a. The selective wavelength light absorbing film or selective wavelength light absorbing layer is a film or layer that absorbs light within a certain wavelength range. The functional film 31 or functional layer 32 may be configured as a single film or layer of any of these functional films and functional layers, or may be configured as a plurality of functional films or functional layers.

[0093] When the functional film 31 is an anti-reflection film, the anti-reflection film may be disposed on one or both of the main surfaces of the optical filter 1 a. The main surface of the optical filter 1 a is the surface having the largest area in the optical filter 1 a.

[0094] The anti-reflection film is formed of, for example, one or more materials. The material constituting the anti-reflection film is not limited to a specific material. The anti-reflection film may be formed of, for example, SiO2, SiO 1.5 , TiO2, or TiO 1.5The antireflection film is a film mainly composed of the above-mentioned material. The antireflection film is formed by, for example, a sol-gel method. The antireflection film may contain hollow particles or particles of a low refractive index material dispersed in its main component. The antireflection film may also contain TiO2, Ta2O3, SiO2, Nb2O5, ZnS, MgF, or a mixture thereof. This film may be formed by a method such as vapor deposition, sputtering, or ion plating. The vapor deposition method may be ion-beam-assisted vapor deposition. The antireflection film may be a single-layer film containing the above-mentioned material, or a multilayer film (dielectric multilayer film) in which films of different materials are alternately stacked. The antireflection film may be formed in contact with the optical filter 1a, or in contact with another functional film or layer formed in contact with the optical filter 1a.

[0095] The antireflective film may be a film containing silicon and formed by a sol-gel method. The sol-gel method allows the formation of an antireflective film at low temperatures and can form a film containing a cross-linked structure formed by —O—Si—O— bonds, similar to glass. This makes the antireflective film more reliable and allows the film to be mainly composed of silica, which has a relatively low refractive index, making the sol-gel method suitable as a method for forming an antireflective film.

[0096] Materials used in the sol-gel method may contain trifunctional silanes containing hydrocarbon groups, such as methyltriethoxysilane (MTES), and tetrafunctional silanes, such as tetraethoxysilane (TEOS). The ratio A1 / A2 of the trifunctional silane content A1 to the tetrafunctional silane content A2 in the material used in the sol-gel method is, for example, 0.5 to 5 on a mass basis. The trifunctional silane can suppress the occurrence of cracks in the film, and the tetrafunctional silane is expected to form a strong skeleton.

[0097] In addition, for example, when the optical filter 1a is formed from a light-absorbing composition containing at least one selected from the group consisting of alkoxysilanes and alkoxysilane hydrolysates, problems such as peeling at the interface between the optical filter 1a and the anti-reflection film are expected to be suppressed. In the sol-gel method, the coating film is baked, for example, at a temperature ranging from 60°C to 170°C. The coating film may be baked preferably at a temperature ranging from 60°C to 150°C, or alternatively at a temperature ranging from 60°C to 115°C. Because the optical filter 1a has the desired heat resistance, a strong anti-reflection film can be formed without problems such as the generation of decomposition products even when the coating film is baked at a high temperature. The baking time for the coating film is, for example, 1 minute to 10 hours, preferably 0.5 hours to 6 hours. Furthermore, baking may be performed under conditions in which the heating temperature is changed stepwise at predetermined intervals, such as 1 hour at 40°C, 1 hour at 60°C, and 1 hour at 85°C.

[0098] When the functional film 31 is a light-reflecting film, the optical filter 1a and the functional film 31 may cooperate to exhibit a predetermined light-blocking ability. Such cooperation makes it possible to reduce or block the transmission of light belonging to a specific wavelength range, and the burden required of the optical filter 1a in terms of light absorption characteristics is likely to be reduced. This makes it easy to reduce, for example, the thickness of the optical filter 1a. Also, for example, it makes it easy to reduce the content of light-absorbing compounds such as light absorbents in the optical filter 1a.

[0099] The selective wavelength light absorbing film is not limited to a specific film. The selective wavelength light absorbing film may be a film of a metal such as Ag (silver), Al (aluminum), Au (gold), or Pt (platinum), or may be a film containing a compound containing one or more of these metals or other metals. In particular, metal films are easily adaptable to a wide wavelength range and tend to have a simple structure. For this reason, metal films can be used as simple films that exhibit light reflection or light absorption functions. Such selective wavelength light absorbing films can be used as neutral density (ND) filters or half mirrors.

[0100] As shown in FIG. 1D, a predetermined functional film 31 or functional layer 32 may be formed on at least one main surface of the laminate including the support 20 and the optical filter 1a.

[0101] For example, an imaging device including the optical filter 1a can be provided. The imaging device may also be called a camera or a camera module. Fig. 2A is a cross-sectional view schematically showing an example of an imaging device according to the present invention. The imaging device 2a includes the optical filter 1a.

[0102] The imaging device 2a further includes a solid-state imaging element 3 and a lens group 5. The solid-state imaging element 3 includes, for example, a CMOS or a CCD. The lens group 5 focuses light from a subject onto the solid-state imaging element 3. The imaging device 2a may further include a case including a shield or housing, a lens driving device, a circuit board for driving the solid-state imaging element 3, a driver, etc. These components and members are not shown in FIG. 2A . In the imaging device 2a, light from a subject passes through the lens group 5 and the optical filter 1a, and light belonging to a specific wavelength range reaches the solid-state imaging element 3.

[0103] FIG. 2B is a cross-sectional view schematically illustrating another example of an imaging device according to the present invention. The imaging device 2b has the same configuration as the imaging device 2a, except for portions that will be particularly described. In the imaging device 2b, an optical filter 1a is disposed on the surface of one or more lenses 5a included in the lens group 5. The imaging device 2b includes a lens 10d with an optical filter, which includes the optical filter 1a and a lens 5a. The imaging device 2b may further include a case including a shield or housing, a lens driving device, a circuit board for driving the solid-state imaging element 3, a driver, and the like. These components and members are not illustrated in FIG. 2B. In the imaging device 2b, light from a subject passes through the lens group 5 including the lens 10d with an optical filter, and light belonging to a specific wavelength range reaches the solid-state imaging element 3. The arrangement of the lens 10d with an optical filter in the lens group 5 is not limited to a specific arrangement.

[0104] In addition to being provided as a digital camera, an imaging device (camera) can be mounted on a smartphone. Additionally, an imaging device can be mounted on a manned or unmanned moving body such as an automobile, a ship, an aircraft, or a drone. In particular, in the field of manned automobiles (hereinafter simply referred to as "automobiles"), an imaging device can be used for preventive safety, surrounding monitoring, or interior monitoring.

[0105] FIG. 3 is a schematic diagram illustrating an automobile equipped with an imaging device according to the present invention. The illustration in FIG. 3 is illustrative, and the use of the imaging device, the functions involved, and the location of the imaging device are not limited to those described below. An imaging device installed inside or outside a vehicle is referred to as an on-board camera here. On-board cameras are installed not only on automobiles but also on all moving objects, including the aforementioned ships, aircraft, and unmanned aerial vehicles such as drones, regardless of whether they are manned or unmanned. An imaging device installed in an automobile may be used, for example, as a drive recorder, for driving assistance functions aimed at ensuring preventive safety, or for monitoring the exterior or interior of the vehicle.

[0106] As shown in Fig. 3, in an automobile 70, the imaging device 7a is a front camera inside the automobile, and the imaging device 7b is a front camera outside the automobile. The imaging device 7c is a rear camera inside the automobile, and the imaging device 7d is a rear camera outside the automobile. The imaging device 7e is a side camera. In Fig. 3, "F" indicates the front side of the automobile 70, and "R" indicates the rear side of the automobile. Each of the imaging devices 7a, 7b, 7c, 7d, and 7e is equipped with an optical filter 1a.

[0107] It is important that imaging devices intended for installation in automobiles be resistant to environmental temperature changes. Automobiles may be used in extremely cold environments near the poles, scorching hot environments directly under the equator, or environments with significant temperature differences between day and night. When an optical filter used in an imaging device contains an organic dye as a light absorber, the light absorber may degrade in a high-temperature environment, significantly reducing its light absorption ability. On the other hand, even if the optical filter 1a is placed in an environment of, for example, 70°C or 125°C, the performance of the optical filter 1a does not deteriorate significantly and can maintain almost its initial performance. Therefore, the optical filter 1a is suitable for imaging devices intended for installation in automobiles.

[0108] Images captured by an onboard camera can be used, for example, in a device for driving assistance functions in a vehicle. Images captured by an onboard camera can be displayed on a predetermined display so that they can be recognized by people inside or outside the vehicle. Alternatively, images captured by an onboard camera can be input into a predetermined computer, which then recognizes the images. This can provide an image sensing technology (hereinafter simply referred to as "image sensing") that performs specific functions based on the results of image analysis in a computer. Image sensing can realize, for example, automatic braking or emergency collision mitigation braking in a vehicle. In addition, image sensing is expected to be applied to autonomous driving.

[0109] The image capturing devices 7a and 7b may be involved in functions such as collision prevention, collision impact mitigation, sign recognition, lane departure warning, lane keeping assist, automatic high beam control, etc. The image capturing devices 7c and 7d may be involved in functions such as collision prevention when reversing, collision impact mitigation, parking assist, etc. The image capturing device 7e may be involved in functions such as rear side approach warning assist, lane change assist, narrow road driving assist, and hit-and-run prevention assist.

[0110] Fig. 4 is a block diagram showing an example of a sensing device according to the present invention. As shown in Fig. 4, the sensing device 80 includes an imaging device 2a, an image processing unit 81, and an output unit 82. The image processing unit 81 is connected to the imaging device 2a and may be configured as an information processing device or a computer that performs predetermined processing on image data obtained from the imaging device 2a. The output unit 82 may include, for example, a display.

[0111] 4 , the output unit 82 is connected to, for example, an electronic control unit (ECU) via a communication path 85. Data generated by processing in the image processing unit 81 is sent from the output unit 82 to the ECU via the communication path 85. The communication protocol of the communication path 85 may be a Controller Area Network (CAN), a Local Interconnect Network (LIN), FlexRay, or Ethernet. One or more of these communication protocols may be selected and combined as the communication protocol of the communication path 85.

[0112] 4 , the sensing device 80 may include a storage unit 83. The storage unit 83 is connected to, for example, the image processing unit 81. For example, data generated by processing in the image processing unit 81 may be stored in the storage unit 83.

[0113] The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0114] 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 Plysurf A208N (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a phosphate ester compound, was added to the copper acetate solution and stirred for 30 minutes to obtain Solution A1.

[0115] 40 g of THF was added to 0.706 g of phenylphosphonic acid and stirred for 30 minutes to obtain B1α solution. 40 g of THF was added to 4.230 g of 4-bromophenylphosphonic acid and stirred for 30 minutes to obtain B1β solution. Next, B1α solution and B1β solution were mixed and stirred for 1 minute to obtain a mixed solution. 8.664 g of methyltriethoxysilane (MTES) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13) and 2.840 g of tetraethoxysilane (TEOS) (manufactured by Kishida Chemical Co., Ltd., special grade) were added to this mixed solution and stirred for another 1 minute to obtain B1 solution.

[0116] While stirring the A1 solution, the B1 solution was added to the A1 solution, and the mixture was stirred at room temperature for 1 minute. Next, 100 g of toluene was added to this solution, and the mixture was stirred at room temperature for 1 minute, yielding the C1 solution. The C1 solution was placed in a flask and heated in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., model: OSB-2100), while a solvent removal treatment was carried out using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model: N-1110SF). The set temperature of the oil bath was adjusted to 105°C. The D1 solution after the solvent removal treatment was then removed from the flask. In this way, the D1 solution containing a light-absorbing compound containing a phosphonic acid having an aryl group and a copper component was obtained.

[0117] 4.500 g of copper acetate monohydrate and 240 g of THF were mixed and stirred for 3 hours to obtain a copper acetate solution, and then 2.573 g of Plysurf A208N was added to the copper acetate solution and stirred for 30 minutes to obtain Solution E1.

[0118] 40 g of THF was added to 2.885 g of n-butylphosphonic acid and stirred for 30 minutes to obtain solution F1.

[0119] While stirring the E1 solution, the F1 solution was added to the E1 solution, and the mixture was stirred at room temperature for 1 minute. Next, 100 g of toluene was added to this solution, and the mixture was stirred at room temperature for 1 minute to obtain the G1 solution. The G1 solution was placed in a flask and heated in an oil bath, and the solvent was removed using a rotary evaporator. The temperature of the oil bath was adjusted to 105°C. The H1 solution after the solvent removal treatment was then removed from the flask. In this way, the H1 solution containing a light-absorbing compound containing a phosphonic acid having an alkyl group and a copper component was obtained.

[0120] The D1 liquid and the H1 liquid were mixed so that the content Cf of phosphonic acid having an aryl group and the content Cs of phosphonic acid having an alkyl group were Cf: Cs = 71:29 on a mass basis, and further, 8.925 g of a curable resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), 0.089 g of a catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), 7.696 g of methyltriethoxysilane (MTES) as a trifunctional alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), 4.015 g of tetraethoxysilane (TEOS) as a tetrafunctional alkoxysilane (Kishida Chemical Co., Ltd., special grade), and 3.476 g of dimethyldiethoxysilane (DMDES) as a bifunctional alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed and stirred for 30 minutes. Next, water was added to the liquid so that the water content after mixing was 700 ppm by mass, without taking into consideration the amount of water contained in copper acetate monohydrate, and the mixture was stirred for 5 minutes, thereby obtaining a light-absorbing composition according to Example 1.

[0121] A mixture was obtained by mixing 0.1 g of a surface antifouling coating agent (manufactured by Daikin Industries, Ltd., product name: Optool DSX, active ingredient concentration: 20% by mass) with 19.9 g of a hydrofluoroether-containing liquid (manufactured by 3M Corporation, product name: Novec 7100). This mixture was stirred for 5 minutes to prepare a fluorine treatment agent (active ingredient concentration: 0.1% by mass).

[0122] The fluorine treatment agent was applied to one main surface of a borosilicate glass substrate (manufactured by SCHOTT, product name: D263 T eco) measuring 130 mm x 100 mm x 0.70 mm. The glass substrate was then left at room temperature for 24 hours to dry the coating of the fluorine treatment agent, and the glass surface was then lightly wiped with a dust-free cloth containing Novec 7100 to remove excess fluorine treatment agent. In this way, a fluorine-treated substrate was prepared.

[0123] The light-absorbing composition according to Example 1 was applied to an 80 mm x 80 mm area at the center of one main surface of a fluorine-treated substrate using a dispenser to form a coating film. The resulting coating film was thoroughly dried at room temperature, then placed in an oven and heated from room temperature to 45°C over 6 hours to remove the solvent and by-products. The temperature was then raised from 45°C to 85°C over 8 hours to further remove the solvent and by-products. The film was then further heated stepwise at 125°C for 3 hours, 150°C for 1 hour, and 170°C for 3 hours to fully promote the reaction. A post-cure was then performed for 24 hours in an environment at 85°C and 85% relative humidity to complete the curing reaction of the coating film. Finally, the cured coating film was peeled off from the fluorine-treated substrate to obtain a film-like optical filter according to Example 1.

[0124] Example 2 A light-absorbing composition according to Example 2 was prepared in the same manner as in Example 1, except that the amount of water added was adjusted so that the water content was 1,470 ppm. An optical filter according to Example 2 was obtained in the same manner as in Example 1, except that the light-absorbing composition according to Example 2 was used instead of the light-absorbing composition according to Example 1.

[0125] Example 3 A light-absorbing composition according to Example 3 was prepared in the same manner as in Example 1, except that the amount of water added was adjusted so that the water content was 4,370 ppm. An optical filter according to Example 3 was obtained in the same manner as in Example 1, except that the light-absorbing composition according to Example 3 was used instead of the light-absorbing composition according to Example 1.

[0126] Example 4 A light-absorbing composition according to Example 4 was prepared in the same manner as in Example 1, except that the amount of water added was adjusted so that the water content was 6,510 ppm. An optical filter according to Example 4 was obtained in the same manner as in Example 1, except that the light-absorbing composition according to Example 4 was used instead of the light-absorbing composition according to Example 1.

[0127] Example 5 A transparent liquid material (anti-reflective coating composition) was prepared as a precursor for an anti-reflective coating, containing alkoxysilane, water, and ethanol. The anti-reflective coating composition contained methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) as the alkoxysilanes in a mass ratio of 4:1.

[0128] An antireflection coating composition was applied to one surface of the optical filter according to Example 1 by spin coating to a predetermined thickness to form a coating film, and the coating film was then left to stand at room temperature for 1 minute to dry. Next, an antireflection coating composition was applied to the other surface of the optical filter according to Example 1 by spin coating to a predetermined thickness to form a coating film, and the coating film was then left to stand at room temperature for 1 minute to dry. In this way, coating films of the antireflection coating precursor were formed on both surfaces of the optical filter according to Example 1. In this state, the optical filter according to Example 1 was heated at 85°C for 1 hour to promote hydrolysis of the alkoxysilane contained in the coating film and condensation polymerization by the generated silanol groups, thereby hardening the coating film, and an optical filter having antireflection coatings on both surfaces was obtained.

[0129] <Comparative Example 1> A light-absorbing composition according to Comparative Example 1 was prepared in the same manner as in Example 1, except that the amount of water added was adjusted so that the water content was 8630 ppm. A filter according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the light-absorbing composition according to Comparative Example 1 was used instead of the light-absorbing composition according to Example 1.

[0130] <Comparative Example 2> Except for not adding water, a light-absorbing composition according to Comparative Example 2 was prepared in the same manner as in Example 1. Except for using the light-absorbing composition according to Comparative Example 2 instead of the light-absorbing composition according to Example 1, an optical filter according to Comparative Example 2 was obtained in the same manner as in Example 1.

[0131] <Comparative Example 3> An optical filter according to Comparative Example 3 was obtained in the same manner as in Example 1, except that the light-absorbing composition according to Comparative Example 2 was used instead of the light-absorbing composition according to Example 1, and heating at 125°C for 3 hours, at 150°C for 1 hour, and at 170°C for 3 hours was not performed.

[0132] <Transmission Spectrum> A V-770 ultraviolet-visible-near-infrared spectrophotometer manufactured by JASCO Corporation was used to measure the transmission spectra of the optical filters according to the Examples and Comparative Examples. At 25°C, light was incident on the optical filters according to the Examples and Comparative Examples at angles of incidence of 0°, 40°, and 60°, and the transmission spectra were measured at wavelengths of 300 nm to 1200 nm. The transmission spectra of the optical filters were measured by fixing the optical filters inside a compact thermostatic chamber manufactured by OPTQUEST, which is capable of adjusting and maintaining the internal temperature, and then placing the compact thermostatic chamber on the spectrophotometer. Table 1 shows parameters that can be observed from the transmission spectra of the optical filters according to the Examples and Comparative Examples at an incident angle of 0°. Table 2 shows parameters that can be observed from the transmission spectra of the optical filters according to Examples 1, 4, and 5 at angles of incidence of 0°, 40°, and 60°. The transmission spectra of the optical filters according to Examples 1, 4, and 5 are shown in Figures 5, 6, and 7, respectively.

[0133] Next, at 70° C., the transmission spectra were measured at wavelengths of 300 nm to 1200 nm when light was incident on the filters according to Examples 1 to 5 and Comparative Example 1, and the optical filters according to Comparative Examples 2 and 3, at incident angles of 0°, 40°, and 60°. Fig. 8 shows the transmission spectra of the optical filter according to Example 1 at an incident angle of 0° at temperatures of 25° C. and 70° C. Table 1 also shows parameters that can be seen from the transmission spectra.

[0134] <Reflection Spectrum> A V-770 ultraviolet-visible-near-infrared spectrophotometer manufactured by JASCO Corporation was used to measure the reflection spectrum of the optical filter. The reflection spectrum was measured at wavelengths of 300 nm to 1200 nm when light was incident on the optical filters according to each Example and Comparative Example at an incident angle of 5° at 25°C. The reflection spectrum was also measured using a small thermostatic oven, similar to the measurement of the transmission spectrum. The reflection spectra of the optical filters according to Examples 1, 4, and 5 are shown in Figures 9, 10, and 11, respectively. Parameters obtained from the obtained reflection spectra are shown in Table 1.

[0135] <Thickness> The thickness of the optical filters according to each of the examples and comparative examples was measured using a laser displacement meter LK-H008 manufactured by Keyence Corp. The results are shown in Table 1.

[0136] <Haze> Using a haze meter HM-65L2 manufactured by Murakami Color Research Laboratory, the haze of the optical filters according to each of the examples and comparative examples was measured in accordance with Japanese Industrial Standard JIS K 7136:2000.

[0137] <Heating Test> After measuring the transmission spectrum, reflection spectrum, thickness, and haze, the optical filters according to each Example and Comparative Example were placed in a thermostatic chamber whose temperature was about room temperature (18°C to 28°C), the temperature inside the thermostatic chamber was raised to 125°C, and the chamber was left standing for 200 hours. The temperature inside the thermostatic chamber was then allowed to naturally decrease to room temperature, and the optical filters were then removed. A DKM400 constant temperature incubator with blower, manufactured by AS ONE Corporation, was used as the thermostatic chamber.

[0138] Next, each optical filter was removed from the thermostatic chamber, and the transmission spectra were measured at wavelengths of 300 nm to 1200 nm when light was incident on the optical filters of each Example and Comparative Example at 25°C and incident angles of 0°, 40°, and 60°. Figures 12, 13, 14, and 15 show the transmission spectra (incident angle 0°, measurement temperature 25°C) before and after the heating test for Example 1, Example 4, Comparative Example 2, and Comparative Example 3, respectively. The values ​​of the following parameters were determined for the transmission spectra of each optical filter at 25°C before the heating test and at 25°C after the heating test. The results are shown in Table 3. Wavelengths in the wavelength range of 350nm to 450nm where the transmittance is 50% Wavelengths in the wavelength range of 600nm to 700nm where the transmittance is 50% Wavelengths in the wavelength range of 600nm to 700nm where the transmittance is 20% Average value of transmittance in the wavelength range of 400nm to 450nm Average value of transmittance in the wavelength range of 450nm to 600nm

[0139] As shown in Table 1, the transmission spectra of the optical filters according to each example at an incident angle of 0° at 25°C before the heating test satisfied the above conditions (i) to (iv). In addition, as shown in Table 3, for example, in the transmission spectra of the optical filters according to Examples 1 and 4 at an incident angle of 0° at 25°C before and after the heating test, the absolute value of the difference between the wavelengths at which the transmittance was 50% within the wavelength range of 350 nm to 450 nm was 8 nm or less. On the other hand, in the transmission spectra of the optical filters according to Comparative Examples 2 and 3 at an incident angle of 0° at 25°C before and after the heating test, the absolute value of the difference between the wavelengths at which the transmittance was 50% within the wavelength range of 350 nm to 450 nm exceeded 8 nm.

[0140] Furthermore, as shown in Table 1, the haze values ​​of the optical filters according to each example before the heating test were all less than 0.5%, making them suitable as optical filters to be mounted in image capture devices, etc. On the other hand, the filter according to comparative example 1 had a haze exceeding 0.5 due to the large amount of added moisture, suggesting that it is not suitable as an optical filter to be mounted in an image capture device.

[0141]

[0142]

[0143]

Claims

1. An optical filter, the optical filter includes a light-absorbing compound and a resin containing the light-absorbing compound; The optical filter has a first transmission spectrum at 25°C and an incident angle of 0° before a heating test in which the optical filter is heated at 125°C for 200 hours, and the first transmission spectrum satisfies the following conditions (i), (ii), (iii), and (iv): the optical filter has, after the heating test, a second transmission spectrum at 25° C. and an incident angle of 0°; The wavelength λ at which the transmittance becomes 50% within the wavelength range of 350 nm to 450 nm in the first transmission spectrum 1-UV 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 350 nm to 450 nm in the second transmission spectrum. 2-UV 25℃ The absolute value of the difference is 8 nm or less. Optical filters. (i) The average transmittance in the wavelength range of 300 nm to 380 nm is 1% or less. (ii) The average transmittance in the wavelength range of 450 nm to 600 nm is 80% or more. (iii) The average transmittance in the wavelength range of 700 nm to 725 nm is 10% or less. (iv) The average transmittance in the wavelength range of 950 nm to 1150 nm is 5% or less.

2. 2. The optical filter according to claim 1, wherein the optical filter has a reflection spectrum at a temperature of 25° C. and an incident angle of 5°, and the reflection spectrum satisfies the following conditions (I) and (II): (I) The maximum reflectance at wavelengths of 300 nm to 400 nm is 8% or less. (II) The average reflectance in the wavelength range of 800 nm to 1150 nm is 10% or less.

3. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The wavelength λ at which the transmittance becomes 50% within the wavelength range of 350 nm to 450 nm in the first transmission spectrum 1-UV 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 350 nm to 450 nm in the third transmission spectrum. UV 70℃ The absolute value of the difference between 3. The optical filter according to claim 1 or 2.

4. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The wavelength λ at which the transmittance becomes 50% within the wavelength range of 600 nm to 700 nm in the first transmission spectrum 1-IR 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 600 nm to 700 nm in the third transmission spectrum. IR 70℃ The absolute value of the difference between 3. The optical filter according to claim 1 or 2.

5. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The wavelength λ at which the transmittance becomes 50% within the wavelength range of 600 nm to 700 nm in the first transmission spectrum 1-IR 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 600 nm to 700 nm in the third transmission spectrum. IR 70℃ The absolute value of the difference between The optical filter according to claim 3 .

6. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The transmittance T at a wavelength of 400 nm in the first transmission spectrum 400 25℃ and the transmittance T at a wavelength of 400 nm in the third transmission spectrum. 400 70℃ 3. The optical filter according to claim 1, wherein the absolute value of the difference between

7. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The transmittance T at a wavelength of 400 nm in the first transmission spectrum 400 25℃ and the transmittance T at a wavelength of 400 nm in the third transmission spectrum. 400 70℃ 4. The optical filter according to claim 3, wherein the absolute value of the difference between

8. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The transmittance T at a wavelength of 400 nm in the first transmission spectrum 400 25℃ and the transmittance T at a wavelength of 400 nm in the third transmission spectrum. 400 70℃ 5. The optical filter according to claim 4, wherein the absolute value of the difference between

9. the optical filter has a third transmission spectrum at an incident angle of 0° at 70°C; The transmittance T at a wavelength of 400 nm in the first transmission spectrum 400 25℃ and the transmittance T at a wavelength of 400 nm in the third transmission spectrum. 400 70℃ 6. The optical filter according to claim 5, wherein the absolute value of the difference between

10. The wavelength λ at which the transmittance becomes 50% within the wavelength range of 600 nm to 700 nm in the first transmission spectrum 1-IR 25℃ and a wavelength λ at which the transmittance is 50% within a wavelength range of 600 nm to 700 nm in the second transmission spectrum. 2-IR 25℃ The absolute value of the difference is 5 nm or less.

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

11. The wavelength λ at which the transmittance is 20% within the wavelength range of 600 nm to 700 nm in the first transmission spectrum 1-20 25℃ and a wavelength λ at which the transmittance is 20% within a wavelength range of 600 nm to 700 nm in the second transmission spectrum. 2-20 25℃ The absolute value of the difference is 5 nm or less.

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

12. The average transmittance T in the wavelength range of 400 nm to 450 nm of the first transmission spectrum 1-450 25℃ and the average value T of the transmittance in the wavelength range of 400 nm to 450 nm of the second transmission spectrum. 2-450 25℃ The absolute value of the difference between 3. The optical filter according to claim 1 or 2.

13. The average transmittance T in the wavelength range of 450 nm to 600 nm of the first transmission spectrum 1-VIS 25℃ and the average value T of the transmittance in the wavelength range of 450 nm to 600 nm of the second transmission spectrum. 2-VIS 25℃ The absolute value of the difference is 3% or less.

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

14. 3. The optical filter of claim 1, having a haze of 0.5% or less.

15. a light absorbing compound; A curable resin; at least one selected from the group consisting of alkoxysilanes and hydrolyzed alkoxysilanes; Water, including Light-absorbing composition.

16. 16. The light-absorbing composition according to claim 15, wherein the content of the water in the light-absorbing composition is 700 parts per million (ppm) to 7000 ppm by mass.

17. 1. A method for manufacturing an optical filter, comprising: The method comprises curing the curable resin of the light-absorbing composition according to claim 15 or 16 by a process including the following heating steps (a), (b), (c), and (d): method. (a) Heating for 2 hours or more at a first heating temperature within the temperature range of room temperature to 60°C (b) heating at a second heating temperature within the temperature range of the first heating temperature to 100°C for 2 hours or more; (c) Heating at a third heating temperature within the temperature range of the second heating temperature to 140°C for 2 hours or more. (d) heating at a fourth heating temperature within the temperature range of the third heating temperature to 200°C for one hour or more;

18. An imaging device comprising the optical filter according to claim 1 or 2.

19. An imaging device; a computer connected to the imaging device, The imaging device comprises the optical filter according to claim 1 or 2. Sensing device.

20. performing predetermined processing on image data obtained by an imaging device by a computer; The imaging device comprises the optical filter according to claim 1 or 2. Sensing method.