Optical filters, optical devices, and light-absorbing compositions

Abstract

The present invention provides an optical filter that blocks some ultraviolet light and infrared light in the wavelength range of 700 to 1000 nm, while having high transmittance in the visible light range and a specific wavelength range with longer wavelengths, and a light-absorbing composition that is advantageous for fabricating such an optical filter. [Solution] The optical filter 1a has a first transmission spectrum that satisfies the following conditions (i), (ii), (iii), and (iv) at 25°C: (i) The minimum transmittance in the wavelength range of 450 nm to 600 nm is 70% or more. (ii) The maximum transmittance in the wavelength range of 300 nm to 370 nm is 5% or less. (iii) The maximum transmittance in the wavelength range of 800 nm to 1000 nm is 5% or less. (iv) The minimum transmittance in the wavelength range of 1500 nm to 1700 nm is 60% or more.

Description

Technical Field

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

Background Art

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

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

[0004] For example, Patent Document 1 describes an optical filter containing a light absorber formed by a phosphonic acid having a phenyl group or a halogenated phenyl group and a copper ion.

[0005] Patent Document 2 describes an optical filter provided with a UV-IR absorption layer capable of absorbing infrared rays and ultraviolet rays. The UV-IR absorption layer contains a UV-IR absorbent formed by a phosphonic acid and copper ions.

[0006] Patent Document 3 describes an infrared cut filter provided with an organic dye-containing layer and a copper phosphonate-containing layer.

[0007] Patent Document 4 describes an optical filter provided with a light absorption film. The light absorption film is formed of a cured product of a liquid composition containing a light absorbent formed by a phosphonic acid having an aryl group and copper ions. Patent Document 4 describes the transmission spectrum of the optical filter at wavelengths from 300 nm to 2200 nm.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] The technologies described in Patent Documents 1 to 4 can absorb some ultraviolet light and infrared light in the wavelength range of 700 to 1000 nm. On the other hand, the technologies described in Patent Documents 1 to 4 have room for reconsideration from the viewpoint of increasing the transmittance of the optical filter in a specific wavelength range having longer wavelengths. Therefore, the present invention provides an optical filter that shields some ultraviolet light and infrared light in the wavelength range of 700 to 1000 nm, while having high transmittance in the visible light range and a specific wavelength range having longer wavelengths. The present invention also provides a light-absorbing composition that is advantageous for manufacturing such an optical filter. [Means for solving the problem]

[0010] The present invention The present invention provides an optical filter having a first transmission spectrum that satisfies the following conditions (i), (ii), (iii), and (iv) at 25°C. (i) The minimum transmittance in the wavelength range of 450 nm to 600 nm is 70% or higher. (ii) The maximum transmittance in the wavelength range of 300 nm to 370 nm is 5% or less. (iii) The maximum transmittance in the wavelength range of 800 nm to 1000 nm is 5% or less. (iv) The minimum transmittance in the wavelength range of 1500 nm to 1700 nm is 60% or higher.

[0011] Furthermore, the present invention is A camera module that acquires image information recognized by the visible light of an object, A TOF sensor that acquires distance measurement information to the target object, The camera module and the optical filter positioned in front of the TOF sensor are provided, We provide optical devices.

[0012] Furthermore, the present invention is Copper complex and, A compound containing a primary alkoxy group having two alkoxy groups in its molecule, and at least one hydrolysis product of the primary alkoxy group containing compound, It contains a second alkoxy group-containing compound having three or four alkoxy groups in the molecule and at least one hydrolysate of the second alkoxy group-containing compound. A light-absorbing composition is provided. [Effects of the Invention]

[0013] The above-described optical filter blocks some ultraviolet light and light in the wavelength range of 700-1000 nm, while having high transmittance in the visible light range and a specific wavelength range with longer wavelengths. Furthermore, such an optical filter can be fabricated using the above-described light-absorbing composition. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a cross-sectional view showing an example of an optical filter according to the present invention. [Figure 2] Figure 2 is a cross-sectional view showing another example of an optical filter according to the present invention. [Figure 3] Figure 3 is a block diagram showing an example of a device equipped with an optical filter according to the present invention. [Figure 4] Figure 4 shows the transmission spectrum of the optical filter according to Example 1. [Figure 5] Figure 5 shows the transmission spectrum of the optical filter according to Example 2. [Figure 6] Figure 6 shows the transmission spectrum of the optical filter according to Example 6. [Figure 7] Figure 7 shows the transmission spectrum of the optical filter according to Example 7. [Figure 8] Figure 8 shows the transmission spectrum of a transparent glass substrate. [Figure 9] Figure 9 shows the transmission spectrum of the optical filter according to Example 8. [Figure 10] Figure 10 shows the transmission spectrum of the optical filter according to Example 11. [Figure 11] Figure 11 shows the transmission spectrum of the optical filter according to Example 16. [Figure 12] Figure 12 shows the transmission spectrum of the optical filter according to Example 19. [Figure 13] Figure 13 shows the transmission spectrum of the optical filter according to Example 20.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following description relates to an example of the present invention, and the present invention is not limited thereto.

[0016] The optical filter 1a shown in FIG. 1 has a first transmission spectrum at 25°C. The first transmission spectrum satisfies the following conditions (i), (ii), (iii), and (iv). (i) The minimum value T of the transmittance within the wavelength range of 450 nm to 600 nm min 450-600 is 70% or more. (ii) The maximum value T of the transmittance within the wavelength range of 300 nm to 370 nm max 300-370 is 5% or less. (iii) The maximum value T of the transmittance within the wavelength range of 800 nm to 1000 nm max 800-1000 is 5% or less. (iv) The minimum value T of the transmittance within the wavelength range of 1500 nm to 1700 nm min 1500-1700 is 60% or more.

[0017] Here, the fact that the minimum value T of the transmittance within the wavelength range of X nm to Y nm min X-Y is A% or more is synonymous with the fact that the transmittance is A% or more throughout the wavelength range of X nm to Y nm. In addition, the fact that the maximum value T of the transmittance within the wavelength range of X'nm to Y'nm max X’-Y’ is B% or less is synonymous with the fact that the transmittance is B% or less throughout the wavelength range of X'nm to Y'nm.

[0018] The optical filter 1a has high transmittance in the visible light range because the first transmission spectrum of the optical filter 1a satisfies condition (i). Minimum value T min 450-600 The percentage should preferably be 75% or higher, and more preferably 80% or higher.

[0019] By satisfying condition (ii) in the first transmission spectrum of optical filter 1a, some ultraviolet light can be blocked. Maximum value T max 300-370 The percentage is preferably 3% or less, and more preferably 1% or less.

[0020] The first transmission spectrum of optical filter 1a satisfies condition (iii), thereby blocking light in the wavelength range of 800 to 1000 nm. Maximum value T max 800-1000 The percentage is preferably 3% or less, and more preferably 1% or less.

[0021] By satisfying condition (iv) of the first transmission spectrum of optical filter 1a, optical filter 1a has high transmittance in a specific wavelength range with longer wavelengths, for example, in the range of 1500 nm to 2000 nm.

[0022] Optical filter 1a has high transmittance in the visible light range and a predetermined infrared range of 1500 nm or more. For this reason, it can be used, for example, as a near-infrared cut filter to block some wavelengths of infrared light that are outside the effective range of the human visual sensitivity curve in a camera module mounted on a portable terminal such as a digital camera or smartphone. In addition, optical filter 1a may be applied to distance measuring devices such as Light detection and ranging (LiDAR), as well as Time of Flight (TOF) type distance measuring devices or their peripheral equipment. When using TOF type sensors in LiDAR, etc., light such as lasers with wavelengths belonging to the near-infrared range of around 900 nm has sometimes been used. However, when using light with wavelengths of around 900 nm, the light receiver such as the sensor may be affected by sunlight. Sunlight contains a lot of light with a wavelength of 900 nm, and background noise may worsen the distance measuring accuracy.

[0023] Therefore, TOF (Time-of-Flight) systems using light such as lasers with wavelengths around 1550 nm, and LiDAR systems utilizing these systems, are being considered. In the solar spectrum, the light intensity and quantity at a wavelength of 1550 nm are smaller than those at a wavelength of 900 nm. For this reason, if the photodetector or its surrounding elements can be designed to correspond to the wavelength range used in LiDAR measurements, it is expected that noise from sunlight will be reduced even during the daytime, and the signal-to-noise ratio (S / N) in the measurements will be improved.

[0024] It is anticipated that devices will emerge that incorporate a camera module for capturing images formed by light in the visible light range that humans can perceive, and a TOF (Time-of-Flight) distance measuring device such as LiDAR, or devices that incorporate a part of the TOF distance measuring function into the aforementioned camera module. For example, a device is envisioned that can acquire images such as video or still images captured by the aforementioned camera module, while also acquiring images containing high-precision distance information from a TOF distance measuring device such as LiDAR. Furthermore, a device is envisioned that can acquire images such as video or still images containing detailed distance information. When optical filter 1a is applied to such a device, it can transmit light with wavelengths corresponding to the range of human visual sensitivity necessary for image formation, and can also transmit light with wavelengths around 1550 nm used in distance measuring devices, or light with longer wavelengths up to 2000 nm. In addition, it can block ultraviolet light and light with wavelengths of 700 nm to 1000 nm or 700 nm to 1100 nm, and optical filter 1a is excellent in terms of convenience, simplicity, and optical properties.

[0025] The optical filter 1a blocks some light by absorption, for example. Therefore, the optical filter 1a is advantageous in that it suppresses the occurrence of flare and ghosting, which are problems inside the camera module or rangefinder.

[0026] The effect of strong light from lasers and LEDs at a wavelength of 1550 nm on the human eye is smaller than that at a wavelength of 900 nm. For example, according to the safety standards for laser products set forth in the IEC60825 standard formulated by the International Electrotechnical Commission, the MPE (The maximum permissible exposure) is 1 × 10⁻¹⁶ for a pulse width of 1 microsecond (μs) at a wavelength of 900 nm. -6 J / cm 2 In contrast, at a wavelength of 1550 nm, the concentration is 1 J / cm². 2Therefore, ensuring human safety from laser light is absolutely essential, and using light with a wavelength of around 1550 nm lowers the hurdle for ensuring safety, which is advantageous from the perspective of expanding the range of measurement targets. In TOF (Time-of-Flight) distance measuring devices, including LiDAR, distance is measured based on the time of flight of light reflected by the object being measured after irradiating it with light. When a person holds a TOF distance measuring device, the reflected light from the object being measured returns to that person. In such cases, if the TOF distance measuring device includes a light emitter that emits light with a wavelength of around 1550 nm, and the TOF distance measuring device is placed near a person's eyes, face, or upper body, or at a similar height, these safety considerations are considered advantageous for adopting optical filter 1a.

[0027] In the first transmission spectrum of optical filter 1a, the minimum value T min 1500-1700 The percentage is preferably 70% or higher, and more preferably 75% or higher.

[0028] In the first transmission spectrum of optical filter 1a, the transmittance at a wavelength of 1550 nm is, for example, 70% or more, preferably 80% or more, and more preferably 85% or more.

[0029] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (v). This makes the first spectrum more compatible with human visual sensitivity in the wavelength range of 550 nm to 800 nm. (v) The first cutoff wavelength λ that exhibits a transmittance of 50% in the wavelength range of 550 nm to 800 nm. C1 It exists within the range of 600nm to 700nm.

[0030] First cutoff wavelength λ C1 Preferably, it exists within the range of 620nm to 680nm.

[0031] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (vi). As a result, optical filter 1a tends to have high transmittance in a predetermined infrared region of 1500 nm or higher. (vi) Second cutoff wavelength λ that exhibits a 50% transmittance in the wavelength range of 1000 nm to 1800 nm C2 It exists within the range of 1150nm to 1500nm.

[0032] Second cutoff wavelength λ C2 It is preferably located within the range of 1200 nm to 1430 nm.

[0033] Furthermore, in the first transmission spectrum of optical filter 1a, the second cutoff wavelength λ C2 and the first cutoff wavelength λ C1 The absolute value of the difference between |λ| C2 -λ C1 The value of | is, for example, 600 nm or more, preferably 650 nm or more, and more preferably 700 nm or more. Furthermore, |λ C2 -λ C1 The value of | is, for example, 800 nm or less, preferably 780 nm or less, and more preferably 760 nm or less.

[0034] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (vii). This makes the first spectrum more compatible with human visual sensitivity in the wavelength range of 350 nm to 450 nm. (vii) Third cutoff wavelength λ that exhibits 50% transmittance in the wavelength range of 350 nm to 450 nm C3 It exists within the range of 360nm to 430nm.

[0035] Furthermore, in the first transmission spectrum of the optical filter 1a, the first cutoff wavelength λ C1 and the third cutoff wavelength λ C3 The absolute value of the difference between |λ| C1 -λ C3The value of | is, for example, 200 nm or more, preferably 210 nm or more, and more preferably 220 nm or more. Furthermore, |λ C1 -λ C3 The value of | is, for example, 270 nm or less, preferably 260 nm or less, and more preferably 250 nm or less.

[0036] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (viii). This allows optical filter 1a to block a portion of infrared radiation having wavelengths of 1000 nm to 1100 nm. (viii) Maximum transmittance T in the wavelength range of 1000 nm to 1100 nm max 1000-1100 The percentage is less than 10%.

[0037] Maximum value T max 1000-1100 Ideally, this should be 5% or less.

[0038] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (ix). This allows optical filter 1a to be used in instruments that perform distance measurement using light in the wavelength range of 1700 nm to 1900 nm. (ix) Minimum transmittance T in the wavelength range of 1700 nm to 1900 nm min 1700-1900 The percentage is over 60%.

[0039] Minimum value T min 1700-1900 The percentage is preferably 65% ​​or higher, and more preferably 70% or higher.

[0040] The first transmission spectrum of optical filter 1a further satisfies, for example, the following condition (x). This allows optical filter 1a to be used in instruments that perform distance measurement using light in the wavelength range of 1900 nm to 2200 nm. (x) Minimum transmittance T in the wavelength range of 1900 nm to 2200 nm min 1900-2200The percentage is over 60%.

[0041] Minimum value T min 1900-2200 The percentage is preferably 65% ​​or higher, and more preferably 70% or higher.

[0042] As shown in Figure 1, the optical filter 1a includes, for example, a light-absorbing layer 10. The light-absorbing layer 10 contains a light-absorbing agent. The thickness of the light-absorbing layer 10 is not limited to a specific value. The light-absorbing layer 10 has a thickness of, for example, 100 μm to 400 μm. This makes it easier to lower the height of the equipment equipped with the optical filter 1a. The thickness of the light-absorbing layer 10 is preferably 120 μm to 350 μm, and more preferably 140 μm to 300 μm.

[0043] The optical filter 1a exhibits a fourth cutoff wavelength λ that, for example, shows a transmittance of 50% in the wavelength range of 550 nm to 800 nm at 70°C. C4 It has a second transmission spectrum with the following characteristics: fourth cutoff wavelength λ C4 and the first cutoff wavelength λ C1 The absolute value of the difference between |λ| C4 -λ C1 | is not limited to a specific value, for example, it can be 15 nm or less. In this case, in the optical filter 1a, the cutoff wavelength, which is the boundary between the transmission band and the shielding band in the wavelength range of 550 nm to 800 nm, is less likely to change even if the ambient temperature of the optical filter 1a fluctuates.

[0044] absolute value |λ C4 -λ C1 The | is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 5 nm or less.

[0045] The optical filter 1a exhibits a fifth cutoff wavelength λ that, for example, shows a transmittance of 50% in the range of wavelengths from 1000 nm to 1800 nm at 70°C. C5 It has a second transmission spectrum with a fifth cutoff wavelength λ. C5 and the second cutoff wavelength λ C2 The absolute value of the difference between |λ| C5 -λC2 | is not limited to a specific value, but for example, it is 30 nm or less. In this case, in the optical filter 1a, the cutoff wavelength, which is the boundary between the transmission band and the shielding band in the wavelength range of 1000 nm to 1800 nm, does not change easily even if the temperature of the environment surrounding the optical filter 1a fluctuates.

[0046] absolute value |λ C5 -λ C2 The | is preferably 20 nm or less.

[0047] The optical filter 1a exhibits a sixth cutoff wavelength λ that, for example, shows a 50% transmittance in the wavelength range of 350 nm to 450 nm at 70°C. C6 It has a second transmission spectrum with the following characteristics: sixth cutoff wavelength λ C6 and the third cutoff wavelength λ C3 The absolute value of the difference between |λ| C6 -λ C3 | is not limited to a specific value, but for example, it is 15 nm or less. In this case, in the optical filter 1a, the cutoff wavelength, which is the boundary between the transmission band and the shielding band in the wavelength range of 350 nm to 450 nm, does not change easily even if the temperature of the environment surrounding the optical filter 1a fluctuates.

[0048] absolute value |λ C6 -λ C3 The | is preferably 10 nm or less, and more preferably 8 nm or less.

[0049] In the first transmission spectrum of optical filter 1a, the average transmittance in the wavelength range of 1530 nm to 1570 nm is, for example, 70% or more, preferably 75% or more, and more preferably 80% or more. Having high transmittance for visible light and high transmittance for light around 1550 nm in the optical filter is advantageous for acquiring images containing distance information obtained by the TOF (Time-of-Flight) distance measurement function.

[0050] In the first transmission spectrum of optical filter 1a, the ratio Tr(1) of the average transmittance in the wavelength range of 1530nm to 1570nm to the average transmittance in the wavelength range of 450nm to 600nm is, for example, 0.8 or more, and preferably 0.85 or more. The ratio Tr(1) is, for example, 1.2 or less, and preferably 1.1 or less.

[0051] In the first transmission spectrum of the optical filter 1a, the average transmittance in the wavelength range of 1800 nm to 2100 nm is, for example, 80% or more, preferably 82% or more, and more preferably 85% or more. The high transmittance of the optical filter 1a in this wavelength range is thought to be due to the low content of functional groups that absorb light in the wavelength range of 1800 nm to 2100 nm, or compounds having such functional groups, in the light-absorbing layer 10.

[0052] The optical filter 1a has the characteristic of having less absorption in a specific wavelength range and higher transmittance in that wavelength range compared to, for example, the optical filter described in Patent Document 4. The first transmission spectrum of the optical filter 1a may have minimum values ​​(absorption peaks) in the wavelength range of 1600 nm to 1800 nm and in the wavelength range of 2100 nm to 2200 nm. In this case, the minimum value of transmittance in the wavelength range of 1600 nm to 1800 nm of the first transmission spectrum of the optical filter 1a is, for example, 70% or more, preferably 75% or more. The minimum value of transmittance in the wavelength range of 2100 nm to 2200 nm of the first transmission spectrum of the optical filter 1a is, for example, 70% or more, preferably 75% or more.

[0053] In the first transmission spectrum of optical filter 1a, the ratio Tr(2) of the minimum transmittance in the wavelength range of 1600nm to 1800nm ​​to the average transmittance in the wavelength range of 1800nm ​​to 2100nm is, for example, 0.8 or more, and preferably 0.85 or more. Also, the ratio Tr(2) is, for example, 1.1 or less, and preferably 1.0 or less.

[0054] In the first transmission spectrum of optical filter 1a, the ratio Tr(3) of the minimum transmittance in the wavelength range of 2100nm to 2200nm to the average transmittance in the wavelength range of 1800nm ​​to 2100nm is, for example, 0.8 or more, and preferably 0.85 or more. Also, Tr(3) is, for example, 1.1 or less, and preferably 1.0 or less.

[0055] As long as the first transmission spectrum of the optical filter 1a satisfies the conditions (i), (ii), (iii), and (iv) above, the material forming the light absorption layer 10 in the optical filter 1a is not limited to a specific material. The light absorption layer 10 may be formed, for example, by curing a predetermined light-absorbing composition. In this case, the light-absorbing composition contains, for example, a copper complex, at least one of a first alkoxy group-containing compound and a hydrolysate of the first alkoxy group-containing compound, and at least one of a second alkoxy group-containing compound and a hydrolysate of the second alkoxy group-containing compound. The first alkoxy group-containing compound is a compound having two alkoxy groups in its molecule. The first alkoxy group-containing compound is, for example, a compound that can be hydrolyzed and condensed. The second alkoxy group-containing compound is a compound having three or four alkoxy groups in its molecule. The second alkoxy group-containing compound is, for example, a compound that can be hydrolyzed and condensed. By curing such a light-absorbing composition, an optical filter that satisfies the conditions (i), (ii), (iii), and (iv) above can be produced. The reason why optical filters satisfying the above conditions (i), (ii), (iii), and (iv) can be fabricated by using such light-absorbing compositions is unclear. It is thought that by adding a first alkoxy group-containing compound and adjusting the amount added, the number of functional groups or groups of functional groups that bond three-dimensionally with the surroundings decreases, and the structure of the polymer in the layer becomes relatively sparse during and after the curing process. For this reason, it is thought that the amount of some molecules having functional groups that may absorb in the infrared region decreases from the layer by evaporation or sublimation. Since these molecules or some functional groups absorb light with wavelengths of 1500 nm to 2000 nm, it is thought that the transmittance of the optical filter is high in this wavelength range as a result.

[0056] The transmission spectrum of the cured product of the light-absorbing composition satisfies, for example, the conditions (i), (ii), (iii), and (iv) above. The transmission spectrum of the cured product of the light-absorbing composition may further satisfy at least one of the other conditions above that the first transmission spectrum of the optical filter 1a satisfies. In this case, the thickness of the cured product of the light-absorbing composition is, for example, 100 μm to 400 μm.

[0057] The copper complex contains, for example, phosphonic acid and a copper component. The copper complex may be at least one selected from the group consisting of compounds containing phosphonic acid having an aryl group and a copper component, and compounds containing phosphonic acid having an alkyl group and a copper component. The copper complex may contain both of these compounds. Because the copper complex contains phosphonic acid and a copper component, the optical filter can absorb light including some ultraviolet light with wavelengths shorter than the visible light range and light with wavelengths exceeding 700 nm while increasing the transmittance in the visible light range including wavelengths of 450 nm to 650 nm. For this reason, the transmission spectrum of the optical filter 1a is easily matched to human visual sensitivity. The copper complex is encapsulated in a transparent material such as resin in the light absorption layer 10, for example.

[0058] When a copper complex is a compound containing a phosphonic acid having an aryl group and a copper component, the copper complex tends to absorb light mainly in the wavelength range of 300 nm to 400 nm and light in the wavelength range of 800 nm to 1000 nm. On the other hand, when a copper complex is a compound containing a phosphonic acid having an alkyl group and a copper component, the copper complex tends to absorb light mainly in the wavelength range of 300 nm to 360 nm and light in the wavelength range of 800 nm to 1100 nm.

[0059] In a light-absorbing composition, by adjusting the ratio of the content of a compound containing an aryl group-containing phosphonic acid and a copper component to the content of a compound containing an alkyl group-containing phosphonic acid and a copper component to a predetermined range, it is easier to increase the light transmittance in the wavelength range of 1500 nm to 1700 nm in the optical filter 1a. Furthermore, by adjusting the ratio of the amount of aryl group-containing phosphonic acid added to the amount of alkyl group-containing phosphonic acid added to the light-absorbing composition to a predetermined range, it is easier to increase the light transmittance in the wavelength range of 1500 nm to 1700 nm in the optical filter 1a.

[0060] Phosphonic acids having an aryl group are not limited to specific phosphonic acids, but include, for example, phenylphosphonic acid, nitrophenylphosphonic acid, hydroxyphenylphosphonic acid, bromophenylphosphonic acid, dibromophenylphosphonic acid, fluorophenylphosphonic acid, difluorophenylphosphonic acid, chlorophenylphosphonic acid, dichlorophenylphosphonic acid, iodophenylphosphonic acid, diiodophenylphosphonic acid, benzylphosphonic acid, bromobenzylphosphonic acid, dibromobenzylphosphonic acid, fluorobenzylphosphonic acid, difluorobenzylphosphonic acid, chlorobenzylphosphonic acid, dichlorobenzylphosphonic acid, iodobenzylphosphonic acid, or diiodobenzylphosphonic acid.

[0061] Phosphonic acids having alkyl groups are not limited to specific phosphonic acids, but include, for example, phosphonic acids having alkyl groups with 1 to 8 carbon atoms.

[0062] In a light-absorbing composition, the content of phosphonic acid having an aryl group (Cf) and the content of phosphonic acid having an alkyl group (Cs) are not limited to a specific relationship. In a light-absorbing composition, the Cf:Cs ratio is, for example, 40:60 to 100:0 by mass, preferably 50:50 to 100:0. This makes it easier for optical filters made using the light-absorbing composition to have the desired transmission characteristics.

[0063] In light-absorbing compositions, the ratio of Cfc content to Ctc content is not limited to a specific value. Ctc content is the content of compounds containing alkoxy groups and their hydrolysates, converted to a total hydrolyzed condensate. Cfc content is the content of compounds containing primary alkoxy groups and their hydrolysates, converted to a total hydrolyzed condensate. The ratio of Cfc content to Ctc content is, for example, 0.01 to 0.6 by mass. As described above, the primary alkoxy group-containing compounds reduce the number of functional groups or groups of functional groups that bond three-dimensionally with their surroundings, and it is thought that the structure of polymers in the layer tends to be relatively sparse during and after curing. A relatively sparse structure is thought to be useful for removing solvents or by-products. On the other hand, a ratio of Cfc content to Ctc content of 0.6 or less promotes the formation of a network within the layer. This allows for the formation of a tack-free light-absorbing layer, and the light-absorbing composition tends to cure easily in the desired state. In addition, the mechanical strength of the cured product of the light-absorbing composition is more resistant to physical or chemical treatment in subsequent processes.

[0064] The ratio of Cfc content to Ctc content is preferably 0.02 to 0.5, and more preferably 0.03 to 0.4, on a mass basis.

[0065] The light-absorbing composition may or may not contain a curable resin. In the light-absorbing composition, the ratio of the solid content Crs of the curable resin to the content Ctc of the compound having an alkoxy group and its hydrolysate converted to a complete hydrolysis condensate is not limited to a specific value. The ratio of the solid content Crs to the content Ctc is, for example, 0 to 2 by mass. The curable resin can improve the density and mechanical strength of the light-absorbing layer 10. On the other hand, by keeping the ratio of the solid content Crs to the content Ctc to 2 or less, it is possible to suppress the inhibition by the curable resin of the function of the primary alkoxy group-containing compound in making the polymer structure in the layer relatively loose.

[0066] The ratio of solid content Crs to content Ctc is preferably 0 to 1.5, more preferably 0 to 1.3, and even more preferably 0 to 1.28 by mass. Thus, the content of curable resin in the light-absorbing composition may be relatively small.

[0067] In light-absorbing compositions, the ratio of Cfc content to total Ctr is not limited to a specific value. Total Ctr is the sum of the Ctc content, calculated by converting the alkoxy group-containing compound and its hydrolysate to a complete hydrolysis condensate, and the Crs content of the curable resin. Cfc content is the content of the first alkoxy group-containing compound and its hydrolysate to a complete hydrolysis condensate. The ratio of Cfc content to total Ctr is, for example, 0.01 to 0.4 by mass. This is thought to result in a relatively sparse polymer structure within the layer during and after curing. On the other hand, a ratio of Cfc content to total Ctr of 0.4 or less allows for the formation of a tack-free light-absorbing layer, and the light-absorbing composition cures to the desired state. The mechanical strength of the cured product of the light-absorbing composition can withstand physical or chemical treatment in subsequent processes. The ratio of Cfc content to total Ctr is preferably 0.02 to 0.35, more preferably 0.02 to 0.3, and even more preferably 0.04 to 0.26, on a mass basis.

[0068] In a light-absorbing composition, the first alkoxy group-containing compound and the second alkoxy group-containing compound may each be, for example, a silicon alkoxide (alkoxysilane), or a metal alkoxide such as Ti and Al. An alkoxide having two alkoxy groups in its molecule is called a difunctional alkoxide, an alkoxide having three alkoxy groups in its molecule is called a trifunctional alkoxide, and an alkoxide having four alkoxy groups in its molecule is called a tetrafunctional alkoxide. Alkoxysilanes having two to four alkoxy groups are called 2- to tetrafunctional alkoxysilanes, respectively.

[0069] Alkoxysilanes undergo hydrolysis and polymerization in the presence of water and acid catalysts to form polymers or inorganic compounds. Tetrafunctional alkoxysilanes undergo hydrolysis and polymerization to form solid compounds represented by SiO2. Trifunctional alkoxysilanes undergo hydrolysis and polymerization to form R-SiO2. 1.5 It forms a solid compound represented by . In this specification, "R-" means an organic component. These compounds can constitute a three-dimensional network. The light-absorbing composition may contain at least one selected from the group consisting of trifunctional alkoxysilanes, hydrolysates of trifunctional alkoxysilanes, tetrafunctional alkoxysilanes, and hydrolysates of tetrafunctional alkoxysilanes. A difunctional alkoxysilane has only two reactive functional groups per molecule. When the light-absorbing composition contains a difunctional alkoxysilane, the number of functional groups or groups of functional groups that bond three-dimensionally with the surroundings decreases, and the polymer structure of the curing process and the layer after curing tends to be relatively sparse. For this reason, it is thought that during the curing process of the light-absorbing composition, the solvent or acetic acid or alcohol produced by the reaction is easily and efficiently discharged to the outside. As a result, it is thought that some molecules having functional groups that can absorb light in a predetermined wavelength range in the infrared region decrease from the layer by evaporation and sublimation, and the absorption of light in that wavelength range may be suppressed.

[0070] Tetrafunctional alkoxysilanes are not limited to specific alkoxysilanes, but include, for example, tetramethoxysilane or tetraethoxysilane. Trifunctional alkoxysilanes are not limited to specific alkoxysilanes. Examples of trifunctional alkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, n-propyltriethoxysilane, n-propyltrimethoxysilane, hexyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanatetopropyltriethoxysilane, or 3-isocyanatetopropyltrimethoxysilane. Difunctional alkoxysilanes are not limited to specific alkoxysilanes. Examples of difunctional alkoxysilanes include dimethyldiethoxysilane, dimethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, or 3-glycidoxypropylmethyldiethoxysilane.

[0071] In a light-absorbing composition, the curable resin may contain a copper complex. The curable resin may contain a compound having an alkoxy group, a hydrolysate of the compound, or a polymer of the compound. When an optical filter is made by curing the light-absorbing composition, the presence of the curable resin improves the density of the layer or film formed by the curing of the light-absorbing composition, and has the advantage of easily increasing the rigidity of the layer or film. On the other hand, by adjusting the content of the curable resin in the light-absorbing composition, the effect of the primary alkoxy group-containing compound in appropriately loosening the layer structure is less likely to decrease.

[0072] The curable resin is not limited to any particular resin. The curable resin is, for example, at least one selected from the group consisting of epoxy resins, urethane resins, acrylic resins, polyolefin resins, and silicone resins.

[0073] The light-absorbing composition may further contain a phosphate ester. In a light-absorbing layer formed using the light-absorbing composition, a compound having an alkoxy group or a hydrolysate of such a compound can appropriately disperse the copper complex while providing higher moisture resistance to the light-absorbing layer compared to a phosphate ester. Therefore, by containing a compound having an alkoxy group or a hydrolysate of such a compound in the light-absorbing composition, the amount of phosphate ester used can be reduced. The light-absorbing composition does not need to contain a phosphate ester.

[0074] Phosphate esters are, for example, phosphate esters having a polyoxyalkyl group. Phosphate esters having a polyoxyalkyl group are not limited to specific phosphate esters. Examples of phosphate esters having a polyoxyalkyl group include: Prisurf A208N: polyoxyethylene alkyl (C12, C13) ether phosphate ester, Prisurf A208F: polyoxyethylene alkyl (C8) ether phosphate ester, Prisurf A208B: polyoxyethylene lauryl ether phosphate ester, Prisurf A219B: polyoxyethylene lauryl ether phosphate ester, Prisurf AL: polyoxyethylene styrene-phenyl ether phosphate ester, Prisurf A212C: polyoxyethylene tridecyl ether phosphate ester, or Prisurf A215C: polyoxyethylene tridecyl ether phosphate ester. All of these are products manufactured by Daiichi Kogyo Seiyaku Co., Ltd. In addition, phosphate esters may also be, for example, NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate ester, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate ester, or NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester. These are all products manufactured by Nikko Chemicals Co., Ltd.

[0075] As shown in Figure 1, the optical filter 1a further comprises a transparent substrate 20. The transparent substrate 20 has a pair of main surfaces parallel to each other. In the optical filter 1a, a light-absorbing layer 10 is disposed on one of the main surfaces of the transparent substrate 20. The optical filter 1a may be modified so that the light-absorbing layer 10 is disposed on both main surfaces of the transparent substrate 20. The light-absorbing layer 10 can be formed, for example, by applying the above-mentioned light-absorbing composition to one or both main surfaces of the transparent substrate 20 and curing it. The light-absorbing layer 10 and the main surfaces of the transparent substrate 20 may be in contact. On the other hand, as long as the first transmission spectrum of the optical filter 1a satisfies the above conditions (i), (ii), (iii), and (iv), other functional layers may be formed between the light-absorbing layer 10 and the main surfaces of the transparent substrate 20. The other functional layer is not limited to a specific layer, and is, for example, a layer that improves the adhesion between the light-absorbing layer 10 and the transparent substrate 20 or a layer other than the layer obtained by curing the above-mentioned light-absorbing composition. The transparency of the transparent substrate 20 is not limited to a specific level, as long as the first transmission spectrum of the optical filter 1a satisfies the above conditions (i), (ii), (iii), and (iv). For example, as the transparent substrate 20, a substrate exhibiting a transmittance of 75% or more at wavelengths of 400 nm to 700 nm can be used when it has a thickness of 0.2 mm. In addition, the transparent substrate 20 may be a substrate having a transmission spectrum exhibiting a transmittance of 75% or more at wavelengths of 1400 nm to 2200 nm.

[0076] The transparent substrate 20 is not limited to a specific substrate. The transparent substrate 20 may be a transparent glass substrate containing glass, or a transparent resin substrate containing resin. Transparent glass substrates have high transparency and a remarkably smooth main surface, and are very inexpensive. In addition, transparent glass substrates have high hardness and a high Young's modulus, so they can withstand manufacturing processes and distribution even when their thickness is small. Transparent resin substrates have high transparency, are lightweight, and are suitable for diverse production. If the transparent substrate 20 is a transparent resin substrate, for example, substrates of various shapes can be supplied inexpensively. The material of the transparent resin substrate is not limited to a specific material. Examples of materials for transparent resin substrates include epoxy resin, urethane resin, acrylic resin, polyethylene resin, polyethylene terephthalate resin, polypropylene resin, polyolefin resin, polyamide resin, polyimide resin, polyvinyl chloride resin, polystyrene resin, or silicone resin.

[0077] The optical filter 1a may be modified to have a configuration in which a light-absorbing layer is disposed on the surface of an optical element such as a lens, diffraction grating, and polarizing element. For example, an optical filter comprising an optical element and a light-absorbing layer can be provided by applying the above-mentioned light-absorbing composition to the surface of an optical element such as a lens and curing it. For example, if the optical filter is configured to include at least one lens from the lens system included in the camera module, light having a desired transmission spectrum can be incident on the image sensor without separately manufacturing and arranging an optical filter. In this way, for example, by forming a light-absorbing layer 10 on at least one surface of a functional optical element, an optical filter that combines the original function of the optical element with the function of light absorption can be provided. The optical element is not limited to the elements listed above. The material included in the optical element is not limited to a specific material and may include, for example, the material listed as an example of the material of the transparent substrate 20.

[0078] The optical filter 1a may be modified as shown in Figure 2, as shown in optical filter 1b. Optical filter 1b is a film-like filter equipped with a light-absorbing layer 10. Optical filter 1b can be obtained, for example, by applying the above-mentioned light-absorbing composition to the main surface of a substrate having a smooth main surface, curing it to form a light-absorbing layer 10, and then detaching the light-absorbing layer 10 from the substrate. The smooth main surface of the substrate is configured such that the optical filter 1b satisfies the above-mentioned conditions (i), (ii), (iii), and (iv). The above-mentioned transparent substrate 20 may be used as the substrate for manufacturing optical filter 1b, or a metal substrate or a ceramic substrate may be used. Optical filter 1b is a film-like filter and is configured as a substrate-less filter. For this reason, optical filter 1b is suitable for thinning and the manufacturing cost of optical filter 1b tends to be low. Optical filter 1b may also be obtained by forming a light-absorbing layer 10 on a substrate and then peeling the light-absorbing layer 10 off the substrate. Before applying the light-absorbing composition to the substrate, a fluororesin coating may be applied to the smooth main surface of the substrate. This allows the light-absorbing layer 10 to be easily peeled off the substrate.

[0079] An optical filter may be obtained by applying the above-mentioned light-absorbing composition to a substrate including a curved surface, a lattice-like structure, or a surface with irregularities, curing it to form a light-absorbing layer 10, and then detaching the light-absorbing layer 10 from the substrate. In this case, since the light-absorbing layer 10 is formed along the surface of the substrate, it has a shape corresponding to the surface of the substrate. Therefore, an optical filter can be manufactured that is suited to the characteristics of the surface of the substrate.

[0080] The optical filter 1a or 1b may be further modified to include, in addition to the light absorption layer 10, an anti-reflective or anti-reflective coating that reduces the reflectance of visible light or light with a wavelength of 1500 nm or more. This makes it easier for the amount of light of that wavelength to reach the image sensor to increase. By further including an anti-reflective or anti-reflective coating in the optical filter, for example, the reflectance of light reflected from the optical filter can be reduced to less than 5%.

[0081] The anti-reflective or anti-reflective coating is formed on at least one surface of the light-absorbing layer 10, for example, by having one or more layers made of one or more types of materials. The materials constituting the anti-reflective or anti-reflective coating are not limited to specific materials. The anti-reflective or anti-reflective coating can be, for example, SiO2 or SiO2. 1.5 The film may be formed by a sol-gel method or the like with the main component being TiO2, or it may be a film in which hollow fine particles or fine particles of a low refractive index material are dispersed in the main component. The anti-reflective or anti-reflective film may contain TiO2, Ta2O3, SiO2, Nb2O5, ZnS, MgF, or a mixture thereof, and may be a film formed by a method such as vapor deposition, sputtering, or ion plating. The vapor deposition method may be ion beam assisted vapor deposition. The anti-reflective or anti-reflective film may be a single-layer film containing the above materials, or it may be a multilayer film in which films of different materials are alternately laminated. Furthermore, the anti-reflective or anti-reflective film may be formed in contact with the light absorption layer 10, or in contact with other functional layers formed in contact with the light absorption layer 10.

[0082] The optical filter 1a or 1b may include, in addition to the light-absorbing layer 10, a film having high reflectivity for light in the wavelength range to be shielded, a so-called light-reflecting film. In this case, the optical filter may satisfy the above-mentioned conditions regarding the transmission spectrum through the cooperation of the light-absorbing layer 10 and the light-reflecting film. By effectively adjusting the spectrum of the light-reflecting film, for example, the thickness of the light-absorbing layer 10 can be reduced. The light-reflecting film can be formed on at least one surface of the light-absorbing layer 10, for example, having one or more layers made of one or more types of materials. The materials constituting the light-reflecting film are not limited to specific materials. The light-reflecting film may be SiO2 or SiO2. 1.5The light-reflective film may be formed by a sol-gel method or the like with the main component being TiO2, or it may be a film in which hollow fine particles or fine particles of a low refractive index material are dispersed in the main component. The light-reflective film may contain TiO2, Ta2O3, SiO2, Nb2O5, ZnS, MgF, or a mixture thereof, and may be a film formed by a method such as vapor deposition, sputtering, or ion plating. The vapor deposition method may be an ion beam-assisted vapor deposition method. The light-reflective film may be a single-layer film containing the above materials, or it may be a multilayer film in which films of different materials are alternately laminated. The light-reflective film may be formed in contact with the light-absorbing layer 10, in contact with other functional layers formed in contact with the light-absorbing layer 10, or in contact with at least one main surface of the transparent substrate 20.

[0083] The optical filter according to the present invention is not limited to the above-described embodiments, and the above-described features relating to the optical filter may be combined as appropriate, as long as they do not contradict each other technically.

[0084] Using the optical filter 1a, for example, the device 50 shown in Figure 3 can be provided. In addition to the optical filter 1a, the device 50 includes a TOF sensor unit 30 and a camera module unit 40. The camera module unit 40 is an element for recognizing light in the visible light range or infrared range and forming an image. The camera module unit 40 acquires image information recognized by light in the visible light range or infrared range, for example. Note that Figure 3 shows only the minimum elements or functions necessary for the explanation. The device 50 may include other elements.

[0085] The TOF sensor unit 30 acquires, for example, distance measurement information to an object. The TOF sensor unit 30 comprises an irradiator 31, a light receiver 33, and a control unit 35. The irradiator 31 emits light LI as illumination light with a wavelength of approximately 1550 nm or within the range of 1500 nm to 2200 nm, irradiating the object G to be measured. The light receiver 33 receives reflected light LR from the object G to be measured. The wavelength of the reflected light LR may be within the range of 1500 nm to 2200 nm. The control unit 35 controls the irradiator 31 and the light receiver 33. A distance measurement information image Id is obtained as an output image from the TOF sensor unit 30. In the distance measurement information image Id, for example, the proximity of the distance to the object G to be measured is represented by differences in intensity or color.

[0086] The irradiator 31 includes, for example, a light-emitting element and an optical element. The light-emitting element is an element such as a laser or LED that emits light with wavelengths included in the above range. The optical element is an element for irradiating the object G to be measured with light from the light-emitting element. The optical element included in the irradiator 31 may include a plurality of lenses, prisms or other refractors or deflectors, or diffusion elements for diffusing light. In Figure 3, the light-emitting element and optical element in the irradiator 31 are not shown.

[0087] The light receiver 33 includes, for example, an optical element and a light-receiving element. The optical element is an element for receiving reflected light LR from the object to be measured G. The optical element included in the light receiver 33 may include multiple lenses, refractors or deflectors such as prisms, or diffusion elements for diffusing light. The optical element focuses the reflected light LR from the object to be measured G onto the light-receiving element. The light-receiving element may be a CCD or CMOS type image sensor, or an avalanche photodiode (APD). In Figure 3, the optical element and light-receiving element in the light receiver 33 are not shown.

[0088] The camera module unit 40 acquires an image of an object illuminated by a reference light. The reference light may be sunlight, or it may be light belonging to the infrared region illuminated by an illuminator placed near the camera module. The camera module unit 40 includes, for example, a camera module 43 and a control unit 45 for controlling the camera module 43. The camera module 43 includes, for example, an optical element and a light-receiving element. The optical element is an element for receiving light from the object. The control unit 45 controls, for example, the optical element and the light-receiving element. The output image from the camera module unit 40 is, for example, a normal image Iu of the object shown in Figure 3. The normal image Iu may be an image that includes the shape and color of the object that can be recognized with visible light. When light belonging to the infrared region is used as the reference light, the device 50 can function as a night vision camera. On the other hand, in this case, attention may be needed regarding the overlap between the wavelength range of the light used by the TOF sensor unit 30 and the wavelength range of the reference light, or the noise caused by such overlap.

[0089] The optical elements included in the camera module 43 may include multiple lenses, or refractors or deflectors such as prisms. The optical elements focus light from the object onto the light-receiving element included in the camera module 43. The light-receiving element may be a CCD or CMOS image sensor. In Figure 3, the optical elements and light-receiving element of the camera module 43 are not shown.

[0090] As shown in Figure 3, the optical filter 1a is placed, for example, between the light receiver 33 and camera module 43 of the TOF sensor unit 30 and the object to be measured G. The optical filter 1a may also be placed between the irradiator 31, light receiver 33, and camera module 43 of the TOF sensor unit 30 and the object to be measured G. In other words, the optical filter 1a may be placed on the front of the device comprising the TOF sensor unit 30 and the camera module 43. The optical filter 1a can transmit light with wavelengths belonging to the visible light range and light with wavelengths belonging to the range of approximately 1550 nm or 1500 nm to 2200 nm with high transmittance, while blocking ultraviolet light and light in the range of wavelengths from 700 nm to 1100 nm. Therefore, the optical filter 1a alone can transmit only the light of wavelengths necessary for the TOF sensor unit 30 and the camera module unit 40 to perform their functions.

[0091] It is anticipated that the number of such devices incorporating both a TOF sensor and a camera module will increase. For example, it is anticipated that both a TOF sensor and a camera module will be incorporated into smartphones and tablet-type information terminals. Because such devices are small and thin, the TOF sensor and camera module may be placed in close proximity. The use of optical filter 1a makes it possible to simplify the configuration around the TOF sensor and camera module.

[0092] The device 50 may further include a cover glass (not shown) for protection of the device 50. This cover glass may be positioned in front of the optical filter 1a, that is, closer to the object to be measured G than the optical filter 1a. The cover glass can protect the optical filter 1a, the TOF sensor unit 30, and the camera module unit 40 from external shocks or temperature changes. For example, the optical filter 1a can be manufactured by forming a light-absorbing layer 10 on a rigid transparent substrate 20 such as glass or sapphire. Since sapphire and the like have particularly high hardness, for example, by positioning the optical filter 1a so that the main surface of the transparent substrate 20 on which the light-absorbing layer 10 is formed faces the camera module, an optical filter 1a that also has a protective function can be provided. [Examples]

[0093] The present invention will be described in more detail by reference to examples. However, the present invention is not limited to the following examples.

[0094] <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 the phosphate ester compound Prysurf A208N (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to the obtained copper acetate solution and stirred for 30 minutes to obtain solution A1. 0.706 g of phenylphosphonic acid was mixed with 40 g of THF and stirred for 30 minutes to obtain solution B1α. 4.230 g of 4-bromophenylphosphonic acid was mixed with 40 g of THF and stirred for 30 minutes to obtain solution B1β. Next, solutions B1α and B1β were mixed and stirred for 1 minute. 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 mixture and stirred for another minute to obtain solution B1. Solution B1 was added to solution A1 while stirring, and stirred at room temperature for 1 minute. Next, 100 g of toluene was added to this solution, and stirred at room temperature for 1 minute to obtain solution C1. Solution C1 was placed in a flask and desolvated using a rotary evaporator (manufactured by Tokyo Rikakikai Co., Ltd., model: N-1110SF) while being heated in an oil bath (manufactured by Tokyo Rikakikai Co., Ltd., model: OSB-2100). The oil bath temperature was set to 105°C. After that, solution D1 was removed from the flask after desolvation. In this way, solution D1 was obtained, which contains a phosphonic acid having an aryl group and a light-absorbing compound containing a copper component.

[0095] 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. Next, 2.573 g of the phosphate ester compound Prysurf A208N was added to the obtained copper acetate solution and stirred for 30 minutes to obtain solution E1. Also, 2.885 g of n-butylphosphonic acid was mixed with 40 g of THF and stirred for 30 minutes to obtain solution F1. Solution F1 was added to solution E1 while stirring and stirred at room temperature for 1 minute. Next, 100 g of toluene was added to this solution and stirred at room temperature for 1 minute to obtain solution G1. Solution G1 was placed in a flask and desolvated using a rotary evaporator while being heated in an oil bath. The oil bath temperature was set to 105°C. After that, solution H1 was removed from the flask after desolvation. In this way, solution H1 containing a light-absorbing compound containing alkyl group phosphonic acid and copper component was obtained.

[0096] Solution D1 and Solution H1 were mixed so that the content of phosphonic acid with an aryl group (Cf) and the content of phosphonic acid with an alkyl group (Cs) were Cf:Cs = 71:29 by mass. Furthermore, a curable resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300), a catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name: CAT-AC), methyltriethoxysilane (MTES) as a trifunctional alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-13), tetraethoxysilane (TEOS) as a tetrafunctional alkoxysilane (manufactured by Kishida Chemical Co., Ltd., special grade), and dimethyldiethoxysilane (DMDES) as a difunctional alkoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE-22) were mixed in the amounts shown in Table 1. This mixture was stirred for 30 minutes to obtain the light-absorbing composition according to Example 1. Table 2 shows the solid content of each alkoxysilane converted to a completely hydrolyzed condensate and the solid content of the curable resin in the light-absorbing composition according to Example 1. In Table 1, the mixing amount (addition amount) of each raw material during mixing or during the preparation of the light-absorbing composition is mainly shown for the other examples and comparative examples.

[0097] 0.1 g of a surface antifouling coating agent (manufactured by Daikin Industries, Ltd., product name: Optool DSX, active ingredient concentration: 20% by mass) and 19.9 g of a hydrofluoroether-containing liquid (manufactured by 3M, product name: Novec 7100) were mixed and stirred for 5 minutes to prepare a fluorine treatment agent (active ingredient concentration: 0.1% by mass). This fluorine treatment agent was applied to one main surface of a borosilicate glass (manufactured by SCHOTT, product name: D263 T eco) with dimensions of 130 mm × 100 mm × 0.70 mm. The glass substrate was then left at room temperature for 24 hours to dry the fluorine treatment agent coating, and then the glass surface was lightly wiped with a dust-free cloth containing Novec 7100 to remove excess fluorine treatment agent. A fluorine-treated substrate was thus prepared.

[0098] A light-absorbing composition according to Example 1 was applied to an 80 mm x 80 mm area in the center of one main surface of a fluorine-treated substrate using a dispenser to form a coating film. After the obtained coating film was thoroughly dried at room temperature, it was placed in an oven and the temperature was increased over 6 hours in the range of room temperature to 45°C to remove the solvent and by-products, and then further increased over 8 hours from 45°C to 85°C to remove the solvent and by-products. After that, the coating film was peeled off the fluorine-treated substrate, and the obtained film was post-cured for a further 24 hours in an environment of 85°C and 85% relative humidity to complete the reaction. After the film had dried to some extent, it was peeled off the substrate, and any remaining solvent and by-products in the film could be removed while further promoting the reaction. The light-absorbing composition according to Example 1 contained a predetermined amount of hydrolyzable alkoxysilane. The post-curing conditions were set with the aim of promoting the hydrolysis and polymerization of the alkoxysilane and the bonding of the polymers. In this way, an optical filter according to Example 1 was obtained.

[0099] <Examples 2-7> Light-absorbing compositions according to Examples 2 to 7 were obtained in the same manner as in Example 1, except that the amount of each raw material added was adjusted as shown in Table 1. Optical filters according to Examples 2 to 7 were obtained in the same manner as in Example 1, except that the light-absorbing compositions according to Examples 2 to 7 were used instead of the light-absorbing composition according to Example 1.

[0100] <Example 8> A light-absorbing composition according to Example 8 was obtained in the same manner as in Example 1, except that dimethyldimethoxysilane (DMDMS) (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM-22) was used as the difunctional alkoxysilane, and the amount of each raw material added was adjusted as shown in Table 1.

[0101] A light-absorbing composition according to Example 8 was applied using a dispenser to an 80mm x 80mm area in the center of one main surface of a borosilicate glass (manufactured by SCHOTT, product name: D263 T eco) having dimensions of 130mm x 100mm x 0.70mm to form a coating film. After the obtained coating film was thoroughly dried at room temperature, it was placed in an oven and the temperature was increased over 6 hours in the range of room temperature to 45°C while removing the solvent and by-products. Further removal of the solvent and by-products was carried out over 8 hours while increasing the temperature from 45°C to 85°C. After that, the coating film was post-cured in an environment of 85°C and 85% relative humidity for 24 hours to complete the reaction. In this way, an optical filter according to Example 8, comprising a glass substrate and a light-absorbing layer as a transparent substrate, was obtained.

[0102] <Examples 9-21> Light-absorbing compositions according to Examples 9 to 21 were obtained in the same manner as in Example 1, except that the amount of each raw material added was adjusted as shown in Table 1. Optical filters according to Examples 9 to 21 were obtained in the same manner as in Example 1, except that the light-absorbing compositions according to Examples 9 to 21 were used instead of the light-absorbing composition according to Example 1.

[0103] <Comparative Example 1> A light-absorbing composition according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the amount of each raw material added was adjusted as shown in Table 1. An optical 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.

[0104] <Measurement of transmission spectrum> Using a V-770 UV-Vis-Near-Infrared Spectrophotometer manufactured by JASCO Corporation, the transmission spectra of the optical filters according to Examples 1-15, Examples 17-21, and Comparative Example 1 at an incident angle of 0° were measured. Unless otherwise specified, the transmission spectra were measured at an ambient temperature of 25°C around the optical filters. The measurement results of the transmission spectra of the optical filters according to Examples 1, 2, 6, 7, 8, 11, 19, and 20 are shown in Figures 4, 5, 6, 7, 9, 10, 12, and 13, respectively. Furthermore, several characteristics related to wavelength and transmittance derived from the measurement results of the transmission spectra of the optical filters according to each example and the optical filter according to Comparative Example 1 are shown in Tables 3 and 4. The transmission spectrum of the borosilicate glass substrate used as a transparent substrate in Example 8 was similarly measured at an incident angle of 0°. The results are shown in Figure 8. As shown in Figure 8, the glass substrate had a transmittance of 90% or more in the wavelength range of at least 360 nm to 2500 nm.

[0105] The optical filter according to Example 16 was placed inside a small constant-temperature chamber manufactured by OPTQUEST, and the temperature inside the chamber was adjusted to 25°C. In this state, the transmission spectrum of the optical filter according to Example 16 at an incident angle of 0° was measured using a U-4100 ultraviolet-visible spectrophotometer manufactured by Hitachi, Ltd. Furthermore, with the temperature inside the small constant-temperature chamber adjusted to 70°C, the transmission spectrum of the optical filter according to Example 16 at an incident angle of 0° was measured in the same manner. The transmission spectra of Example 16 at each temperature are shown in Figure 11. In Figure 11, the solid line graph shows the transmission spectrum at 25°C, and the dashed line graph shows the transmission spectrum at 70°C. Several characteristics related to wavelength and transmittance derived from the measurement results of the transmission spectrum of the optical filter according to Example 16 are shown in Tables 3 and 4.

[0106] <Thickness measurement> The thickness of the optical filters for each example and Comparative Example 1 was measured using a Keyence LK-H008 laser displacement meter. The results are shown in Table 3. Note that the thickness of the glass substrate is not taken into account for the optical filter in Example 8.

[0107] As shown in Table 3, the optical filters according to each example satisfied conditions (i), (ii), (iii), (iv), (v), (vi), (vii), (viii), (ix), and (x). The optical filter according to Example 8 demonstrates that a desired optical filter can be obtained even if the light-absorbing composition does not contain a curable resin. On the other hand, the optical filter according to Comparative Example 1 did not satisfy condition (ii).

[0108] In the optical filter according to Example 21 and the optical filter according to Comparative Example 1, the minimum transmittance in the wavelength range of 1500 nm to 1700 nm was lower than that of the optical filters according to Examples 1 to 20. Therefore, it was suggested that in the light-absorbing composition, satisfying the relationship Cf:Cs = 50:50 to 100:0 on a mass basis for the content of phosphonic acid having an aryl group Cf and the content of phosphonic acid having an alkyl group Cs is advantageous in increasing the minimum transmittance in the wavelength range of 1500 nm to 1700 nm.

[0109] As shown in Figure 11 and Table 3, it can be seen that the cutoff wavelengths of the transmission spectrum of the optical filter according to Example 16 in the range of 550 nm to 800 nm, the cutoff wavelengths in the range of 1000 nm to 1800 nm, and the cutoff wavelengths in the range of 350 nm to 450 nm do not change significantly even when the temperature of the optical filter changes from 25°C to 70°C.

[0110] [Table 1]

[0111] [Table 2]

[0112] Table 3

[0113] Table 4

Claims

1. An optical filter having a first transmission spectrum that satisfies the following conditions (i), (ii), (iii), and (iv) at 25°C. (i) The minimum transmittance in the wavelength range of 450 nm to 600 nm is 70% or higher. (ii) The maximum transmittance in the wavelength range of 300 nm to 370 nm is 5% or less. (iii) The maximum transmittance in the wavelength range of 800 nm to 1000 nm is 5% or less. (iv) The minimum transmittance in the wavelength range of 1500 nm to 1700 nm is 60% or more.

2. The optical filter according to claim 1, wherein the first transmission spectrum further satisfies the following condition (v). (v) The first cutoff wavelength that exhibits a 50% transmittance within the wavelength range of 550 nm to 800 nm is located within the range of 600 nm to 700 nm.

3. The optical filter according to claim 1 or 2, wherein the first transmission spectrum further satisfies the following condition (vi). (vi) A second cutoff wavelength that exhibits a 50% transmittance within the wavelength range of 1000 nm to 1800 nm exists within the range of 1150 nm to 1500 nm.

4. The optical filter according to any one of claims 1 to 3, wherein the first transmission spectrum further satisfies the following condition (vii). (vii) A third cutoff wavelength that exhibits a 50% transmittance within the wavelength range of 350 nm to 450 nm exists within the range of 360 nm to 430 nm.

5. The optical filter according to any one of claims 1 to 4, wherein, in the first transmission spectrum, the absolute value of the difference between a first cutoff wavelength showing a transmittance of 50% in the range of 550 nm to 800 nm and a second cutoff wavelength showing a transmittance of 50% in the range of 1000 nm to 1800 nm is 600 nm or more and 800 nm or less.

6. The optical filter according to any one of claims 1 to 5, wherein in the first transmission spectrum, the absolute value of the difference between a first cutoff wavelength showing a transmittance of 50% in the range of 550 nm to 800 nm and a third cutoff wavelength showing a transmittance of 50% in the range of 350 nm to 450 nm is 200 nm or more and 270 nm or less.

7. The optical filter according to any one of claims 1 to 6, wherein the first transmission spectrum further satisfies the following condition (viii). (viii) The maximum transmittance in the wavelength range of 1000 nm to 1100 nm is 10% or less.

8. The optical filter according to any one of claims 1 to 7, wherein the first transmission spectrum further satisfies the following condition (ix). (ix) The minimum transmittance in the wavelength range of 1700 nm to 1900 nm is 60% or more.

9. The optical filter according to any one of claims 1 to 8, wherein the transmittance at a wavelength of 1550 nm in the first transmission spectrum is 70% or more.

10. The optical filter according to any one of claims 1 to 9, wherein the first transmission spectrum further satisfies the following condition (x). (x) The minimum transmittance in the wavelength range of 1900 nm to 2200 nm is 60% or more.

11. An optical filter according to any one of claims 1 to 10, comprising a light-absorbing layer containing a light-absorbing agent and having a thickness of 100 μm to 400 μm.

12. At 70°C, it has a second transmission spectrum with a fourth cutoff wavelength that exhibits a transmittance of 50% in the wavelength range of 550 nm to 800 nm. The optical filter according to claim 2, wherein the absolute value of the difference between the fourth cutoff wavelength and the first cutoff wavelength is 15 nm or less.

13. At 70°C, it has a second transmission spectrum with a fifth cutoff wavelength that exhibits a transmittance of 50% in the range of 1000 nm to 1800 nm. The optical filter according to claim 3, wherein the absolute value of the difference between the fifth cutoff wavelength and the second cutoff wavelength is 30 nm or less.

14. At 70°C, it has a second transmission spectrum with a sixth cutoff wavelength that exhibits a transmittance of 50% in the wavelength range of 350 nm to 450 nm. The optical filter according to claim 4, wherein the absolute value of the difference between the sixth cutoff wavelength and the third cutoff wavelength is 15 nm or less.

15. A camera module that acquires image information recognized by the visible light of an object, A TOF sensor that acquires distance measurement information to the target object, The camera module and the optical filter according to any one of claims 1 to 14, disposed in front of the TOF sensor, are provided. optical equipment.

16. The optical device according to claim 15, wherein the TOF sensor includes an irradiator that directs light with wavelengths in the range of 1500 nm to 2200 nm toward an object, a light receiver that receives reflected light from the object with wavelengths in the range of 1500 nm to 2200 nm, and a control unit.

17. Copper complex and, A compound containing a primary alkoxy group having two alkoxy groups in its molecule, and at least one hydrolysis product of the primary alkoxy group containing compound, It contains a second alkoxy group-containing compound having three or four alkoxy groups in the molecule and at least one hydrolysate of the second alkoxy group-containing compound. Light-absorbing composition.

18. The light-absorbing composition according to claim 17, wherein the ratio of the content of the first alkoxy group-containing compound and the hydrolysis of the first alkoxy group-containing compound, converted to a complete hydrolysis condensate, to the content of the compound having an alkoxy group and the hydrolysis of the compound, converted to a complete hydrolysis condensate, is 0.01 to 0.6 by mass.

19. The light-absorbing composition according to claim 17 or 18, wherein the ratio of the solid content of the curable resin to the content of the compound having an alkoxy group and the hydrolysate of the compound, converted to a complete hydrolysis condensate, is 0 to 2 by mass.

20. The light-absorbing composition according to any one of claims 17 to 19, wherein the ratio of the content of the first alkoxy group-containing compound and the hydrolysate of the first alkoxy group-containing compound, converted to a complete hydrolyzed condensate, to the sum of the content of the compound having an alkoxy group and the hydrolysate of the compound, converted to a complete hydrolyzed condensate, to the sum of the content of the compound and the solid content of the curable resin is 0.01 to 0.4 by mass.

21. The light-absorbing composition according to any one of claims 17 to 20, wherein the content of phosphonic acid having an aryl group Cf and the content of phosphonic acid having an alkyl group Cs satisfy the relationship Cf:Cs = 50:50 to 100:0 by mass.

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