JP6259157B1 - Optical filter and imaging device - Google Patents

Abstract

An optical filter is provided which is advantageous in preventing color unevenness from occurring in an image generated by an imaging apparatus. An optical filter (1a) includes a light absorption layer (10). The light absorption layer absorbs at least part of light in the near infrared region. The optical filter (1a) satisfies a predetermined condition regarding transmittance when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at incident angles of 0 °, 30 °, and 40 °. Also, nine differences in IEθrR, IEθgG, and IEθbB defined for incident angles θ ° of 0 °, 30 °, and 40 ° respectively, and IEθrR, IEθgG, and IEθbB for the same two incident angles θ °. A range which is a difference obtained by subtracting the minimum value from the maximum value of the three differences satisfies the predetermined condition. [Selection] Figure 1A

Description

  The present invention relates to an optical filter and an imaging device.

  2. Description of the Related Art Conventionally, an imaging apparatus including an optical filter such as a near infrared cut filter is known. For example, Patent Document 1 describes a near-infrared cut filter including a laminated plate having a resin layer containing a near-infrared absorber on at least one surface of a glass plate substrate. For example, this near-infrared cut filter has a dielectric multilayer film on at least one side of a laminate. In this near-infrared cut filter, the absolute value | Ya−Yb | of the difference between the wavelength value (Ya) and the wavelength value (Yb) is less than 15 nm. The wavelength value (Ya) is a wavelength value at which the transmittance is 50% when measured from the vertical direction of the near-infrared cut filter in the wavelength range of 560 to 800 nm. The wavelength value (Yb) is a wavelength value at which the transmittance is 50% when measured from an angle of 30 ° with respect to the vertical direction of the near-infrared cut filter in the wavelength range of 560 to 800 nm. Thus, according to Patent Document 1, the angle dependency of the transmission characteristics in the near-infrared cut filter is adjusted to be small.

Patent Document 2 describes a near-infrared cut filter including a near-infrared absorbing glass substrate, a near-infrared absorbing layer, and a dielectric multilayer film. The near infrared absorbing layer contains a near infrared absorbing dye and a transparent resin. Patent Document 2 describes a solid-state imaging device including the near-infrared cut filter and a solid-state imaging element. According to Patent Document 2, by laminating a near-infrared absorbing glass substrate and a near-infrared absorbing layer, the dielectric multilayer film inherently has an angle dependency in which the shielding wavelength shifts depending on the incident angle of light. The effect can be almost eliminated. For example, in Patent Document 2, the transmittance (T ₀ ) at an incident angle of 0 ° and the transmittance (T ₃₀ ) at an incident angle of 30 ° in the near infrared cut filter are measured.

  Patent Documents 3 and 4 describe an infrared cut filter including a dielectric substrate, an infrared reflection layer, and an infrared absorption layer. The infrared reflecting layer is formed of a dielectric multilayer film. The infrared absorbing layer contains an infrared absorbing dye. Patent Documents 3 and 4 describe an imaging device including this infrared cut filter. Patent Documents 3 and 4 describe the transmittance spectrum of the infrared cut filter when the incident angles of light are 0 °, 25 °, and 35 °.

Patent Document 5 describes a near-infrared cut filter that includes an absorption layer and a reflection layer and satisfies predetermined requirements. For example, in this near-infrared cut filter, the integral value T _{0 (600-725)} of the transmittance of light having a wavelength of 600 to 725 nm in the spectral transmittance curve at an incident angle of 0 ° and the spectral transmittance curve at an incident angle of 30 °. The difference | T _{0 (600-725)} −T _{30 (600-725)} | from the integrated value T _{30 (600-725)} of the transmittance of light having a wavelength of 600 to 725 nm is 3% · nm or less. Patent Document 5 also describes an imaging device including the near infrared cut filter.

Patent Documents 6 and 7 describe optical filters that include a light absorption layer and a near-infrared reflective layer and satisfy ΔE ^* ≦ 1.5. ΔE ^* is a color difference between light that is perpendicularly incident on the optical filter and transmitted through the optical filter, and light that is incident at an angle of 30 ° from the direction perpendicular to the optical filter and is transmitted through the optical filter. The light absorption layer includes, for example, a binder resin, and a light absorber is dispersed in the binder resin. The near-infrared reflective layer is, for example, a dielectric multilayer film. Patent Documents 6 and 7 also describe an imaging device such as a camera provided with this optical filter.

JP 2012-103340 A International Publication No. 2014/030628 US Patent Application Publication No. 2014/0300956 US Patent Application Publication No. 2014/0063597 Japanese Patent No. 6119920 Korean Registered Patent No. 10-1474902 Korean Registered Patent No. 10-1527822

  In the above-mentioned patent documents, the characteristics of the optical filter when the incident angle of light to the optical filter is larger than 35 ° (for example, 40 °) are not specifically examined. An imaging device such as a camera is equipped with an image sensor having R (red), G (green), and B (blue) color filters. In the above-mentioned patent document, the characteristics of these color filters are described. The suitability of has not been studied. Therefore, the present invention is easily adapted to the characteristics of a color filter used in an image sensor mounted on an imaging device even when the incident angle of light is larger, and color unevenness is generated in an image generated by an imaging device such as a camera. The present invention provides an optical filter having characteristics advantageous in preventing the occurrence of The present invention also provides an imaging device provided with this optical filter.

The present invention
An optical filter,
A light absorption layer containing a light absorber is provided,
When light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at incident angles of 0 °, 30 °, and 40 °, the following conditions are satisfied:
(I) Spectral transmittance at a wavelength of 700 nm is 3% or less.
(Ii) Spectral transmittance at a wavelength of 715 nm is 1% or less.
(Iii) Spectral transmittance at a wavelength of 1100 nm is 7.5% or less.
(Iv) The average transmittance at a wavelength of 700 nm to 800 nm is 1% or less.
(V) The average transmittance at a wavelength of 500 nm to 600 nm is 85% or more.
(Vi) Spectral transmittance at a wavelength of 400 nm is 45% or less.
(Vii) The spectral transmittance at a wavelength of 450 nm is 80% or more.
The spectral transmittance of the optical filter at the wavelength λ when the incident angle is θ ° is expressed as T _θ (λ),
The product of T _θ (λ) and R (λ), G (λ), and B (λ), which is a function of the wavelength λ defined by Table (I) in the wavelength range of 400 nm to 700 nm. Functions obtained by normalizing the respective functions determined with respect to the incident angle θ ° so that the maximum value is 1 are _represented as CR _θ (λ), CG _θ (λ), and CB _θ (λ),
Stiles & Burch (1959) The function of wavelength λ obtained by normalizing the color matching functions defined in 10-deg, RCB CMFs so that the maximum value is 1, respectively, is r (λ), g (λ), and b (λ),
When the wavelength λ which is a variable of CR _θ (λ), CG _θ (λ), and CB _θ (λ) is expressed as λ (n) = (Δλ × n + 400) nm as a function of n which is an integer of 0 or more. (Where Δλ = 5),
Nine differences in IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB defined for each of incident angles θ ° of 0 °, 30 °, and 40 ° by the following equations (1)-(3) A range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of IE _θ ^rR , IE _θ ^gG , and IE _θ ^{bB for} the same two incident angles θ ° satisfies the condition shown in Table (II).
An optical filter is provided.

The present invention also provides:
A lens system,
An image sensor that receives light that has passed through the lens system;
A color filter disposed in front of the image sensor and having three color filters of R (red), G (green), and B (blue);
The optical filter disposed in front of the color filter, and
An imaging device is provided.

  The optical filter described above easily adapts to the characteristics of a color filter used in an imaging device such as a camera even when the incident angle of light is larger, and prevents color unevenness from occurring in an image generated by the imaging device. Advantageous properties. Further, in the above-described imaging apparatus, even when the incident angle of light is larger, color unevenness hardly occurs in the generated image.

FIG. 1A is a cross-sectional view showing an example of the optical filter of the present invention. FIG. 1B is a cross-sectional view showing another example of the optical filter of the present invention. FIG. 1C is a cross-sectional view showing still another example of the optical filter of the present invention. FIG. 1D is a cross-sectional view showing still another example of the optical filter of the present invention. FIG. 1E is a cross-sectional view showing still another example of the optical filter of the present invention. FIG. 1F is a cross-sectional view showing still another example of the optical filter of the present invention. FIG. 2 is a graph of R (λ), G (λ), and B (λ). FIG. 3 is a cross-sectional view showing an example of the imaging apparatus of the present invention. 4A is a transmittance spectrum of a semi-finished product of the optical filter according to Example 1. FIG. FIG. 4B is a transmittance spectrum of another semi-finished product of the optical filter according to Example 1. 4C is a transmittance spectrum of the laminate according to Reference Example 1. FIG. FIG. 4D is a transmittance spectrum of the laminate according to Reference Example 2. FIG. 4E is a transmittance spectrum of the optical filter according to the first embodiment. FIG. 5A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 1, and the normalized color matching function r (λ). is there. FIG. 5B is a graph illustrating a relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to the first embodiment, and the normalized color matching function g (λ). is there. FIG. 5C is a graph illustrating a relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to the first embodiment, and the normalized color matching function b (λ). is there. 6A is a transmittance spectrum of the laminate according to Reference Example 3. FIG. 6B is a transmittance spectrum of the optical filter according to Example 2. FIG. FIG. 7A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 2, and the normalized color matching function r (λ). is there. FIG. 7B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Example 2, and the normalized color matching function g (λ). is there. FIG. 7C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Example 2, and the normalized color matching function b (λ). is there. FIG. 8A is a transmittance spectrum of a semi-finished product of the optical filter according to Example 3. FIG. 8B is a transmittance spectrum of the optical filter according to Example 3. FIG. 9A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 3, and the normalized color matching function r (λ). is there. FIG. 9B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Example 3, and the normalized color matching function g (λ). is there. FIG. 9C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Example 3, and the normalized color matching function b (λ). is there. FIG. 10A is a transmittance spectrum of the laminate according to Reference Example 4. FIG. 10B is a transmittance spectrum of the optical filter according to Example 4. FIG. 11A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 4, and the normalized color matching function r (λ). is there. FIG. 11B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Example 4, and the normalized color matching function g (λ). is there. FIG. 11C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Example 4, and the normalized color matching function b (λ). is there. FIG. 12 is a transmittance spectrum of the optical filter according to Example 5. FIG. 13A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 5, and the normalized color matching function r (λ). is there. FIG. 13B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Example 5, and the normalized color matching function g (λ). is there. FIG. 13C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Example 5, and the normalized color matching function b (λ). is there. FIG. 14A is a transmittance spectrum of a semi-finished product of the optical filter according to Example 6. FIG. 14B is a transmittance spectrum of the optical filter according to Example 6. FIG. 15A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Example 6, and the normalized color matching function r (λ). is there. FIG. 15B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Example 6, and the normalized color matching function g (λ). is there. FIG. 15C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Example 6, and the normalized color matching function b (λ). is there. FIG. 16A is a transmittance spectrum of a semi-finished product of the optical filter according to Comparative Example 1. FIG. 16B is a transmittance spectrum of the laminate according to Reference Example 5. FIG. 16C is a transmittance spectrum of the optical filter according to Comparative Example 1. FIG. 17A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Comparative Example 1, and the normalized color matching function r (λ). is there. FIG. 17B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Comparative Example 1, and the normalized color matching function g (λ). is there. FIG. 17C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Comparative Example 1, and the normalized color matching function b (λ). is there. 18A is a transmittance spectrum of an infrared-absorbing glass substrate of an optical filter according to Comparative Example 2. FIG. FIG. 18B is a transmittance spectrum of the laminate according to Reference Example 6. FIG. 18C is a transmittance spectrum of the laminate according to Reference Example 7. FIG. 18D is a transmittance spectrum of the optical filter according to Comparative Example 2. FIG. 19A is a graph showing the relationship between the normalized spectral sensitivity function CR _θ (λ) based on the transmittance spectrum and R (λ) of the optical filter according to Comparative Example 2, and the normalized color matching function r (λ). is there. FIG. 19B is a graph showing the relationship between the normalized spectral sensitivity function CG _θ (λ) based on the transmittance spectrum and G (λ) of the optical filter according to Comparative Example 2, and the normalized color matching function g (λ). is there. FIG. 19C is a graph showing the relationship between the normalized spectral sensitivity function CB _θ (λ) based on the transmittance spectrum and B (λ) of the optical filter according to Comparative Example 2, and the normalized color matching function b (λ). is there.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to an example of the present invention, and the present invention is not limited to these.

  The present inventors have devised the optical filter according to the present invention based on the new knowledge obtained by the following studies on the optical filter.

  An optical filter that shields unnecessary light other than visible light is disposed in a camera module or an imaging device mounted on a portable information terminal such as a smartphone. The use of an optical filter provided with a light absorption layer in order to shield unnecessary light has been studied. As in the optical filters described in Patent Documents 1 to 7, the optical filter provided with the light absorbing layer often further includes a reflective film formed of a dielectric multilayer film.

  In the reflection film constituted by the dielectric multilayer film, the wavelength band of the light beam to be transmitted and the wavelength band of the light beam to be reflected are determined by the interference of the light beam reflected on the front and back surfaces of each layer of the reflection film. Light can be incident on the optical filter from various incident angles. The optical path length in the reflective film varies depending on the incident angle of light on the optical filter. As a result, the wavelength band of transmitted light and reflected light changes to the short wavelength side. Therefore, in order to prevent the transmittance characteristics of the optical filter from fluctuating greatly depending on the incident angle of light, the boundary between the wavelength band of the light beam to be shielded and the wavelength band of the light beam to be transmitted is determined by light absorption, and the dielectric multilayer film It can be considered that the wavelength band of the light beam to be reflected is separated from the wavelength band of the light beam to be transmitted.

  Patent Documents 1 and 2 evaluate light transmission characteristics in a near-infrared cut filter when the incident angles of light are 0 ° and 30 °. In Patent Documents 3 and 4, the transmittance spectrum of the infrared cut filter when the incident angles of light are 0 °, 25 °, and 35 ° is evaluated. In recent years, it has been demanded to realize a wider angle of view and a further reduction in height in a camera module mounted on a portable information terminal such as a smartphone. For this reason, in the optical filter, it is desirable that the wavelength band and the amount of light to be transmitted hardly change even when the incident angle of light is larger (for example, 40 °).

  In an optical filter provided with a reflective film composed of a dielectric multilayer film, if the incident angle of light is large, the reflectance of light is locally increased in the wavelength band of light rays that originally want to suppress reflection and achieve high transmittance. May increase. This causes a problem called ripple in which the transmittance is locally reduced in the optical filter. For example, even if the optical filter is designed so that no ripple occurs when the incident angle of light is 0 ° to 30 °, the ripple is likely to occur when the incident angle of light increases to 40 °.

  An index that comprehensively evaluates the effect of shifting the boundary between the wavelength band of transmitted light and the wavelength band of light to be shielded by fluctuations in the incident angle of light and the occurrence of ripples has been established. Absent. According to the technique described in Patent Document 5, the boundary between the visible light wavelength band to be transmitted and the near-infrared wavelength band to be reflected or absorbed is stable against fluctuations in the incident angle of light. However, the technique described in Patent Document 5 has room for improvement from the viewpoint of shift and ripple generation due to the change in the incident angle at the boundary between the visible light wavelength band and the ultraviolet wavelength band.

According to Patent Documents 6 and 7, although the characteristics of the optical filter alone are specified by the color difference ΔE ^* , it is not guaranteed that the optical filter is compatible with an actual imaging device. This is because an RGB color filter is incorporated in each pixel of the image sensor provided in the imaging apparatus, and the amount of light detected by each pixel of the sensor is equal to the spectral transmittance of the optical filter that blocks unnecessary light. This is because it correlates with the product of the spectral transmittance of the color filter. For this reason, it is desirable that the optical filter has characteristics that match the characteristics of the color filter used in the imaging apparatus.

  Based on such circumstances, even when the incident angle of light is larger, studies were conducted day and night on an optical filter that easily matches the characteristics of the color filter used in the imaging device. In addition, the optical filter having characteristics advantageous for preventing the occurrence of uneven color in the image generated by the imaging apparatus has been studied day and night. As a result, the present inventors have devised an optical filter according to the present invention.

  In this specification, “spectral transmittance” is transmittance when incident light of a specific wavelength is incident on an object such as a sample, and “average transmittance” is spectral transmittance within a predetermined wavelength range. It is the average value of the rate. Further, in this specification, the “transmittance spectrum” is obtained by arranging spectral transmittances at respective wavelengths within a predetermined wavelength range in order of wavelength.

  In this specification, the “IR cutoff wavelength” indicates a spectral transmittance of 50% in a wavelength range of 600 nm or more when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at a predetermined incident angle. It means wavelength. The “UV cutoff wavelength” means a wavelength that exhibits a spectral transmittance of 50% in a wavelength range of 450 nm or less when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at a predetermined incident angle. .

As shown in FIG. 1A, the optical filter 1 a includes a light absorption layer 10. The light absorption layer 10 contains a light absorber, and the light absorber absorbs at least part of light in the near infrared region. The optical filter 1a satisfies the following conditions when light having a wavelength of 300 nm to 1200 nm is incident on the optical filter 1a at incident angles of 0 °, 30 °, and 40 °.
(I) Spectral transmittance at a wavelength of 700 nm is 3% or less.
(Ii) Spectral transmittance at a wavelength of 715 nm is 1% or less.
(Iii) Spectral transmittance at a wavelength of 1100 nm is 7.5% or less.
(Iv) The average transmittance at a wavelength of 700 nm to 800 nm is 1% or less.
(V) The average transmittance at a wavelength of 500 nm to 600 nm is 85% or more.
(Vi) Spectral transmittance at a wavelength of 400 nm is 45% or less.
(Vii) The spectral transmittance at a wavelength of 450 nm is 80% or more.

  Since the optical filter 1a satisfies the above conditions (i) to (vii), even if it is incorporated in a camera module or an imaging device equipped with a wide-angle lens, it can block unnecessary light rays without impairing the brightness.

The spectral transmittance of the optical filter 1a at the wavelength λ when the incident angle of light is θ ° is represented as T _θ (λ). Further, T _θ (λ) and R (λ), G (λ), and B (λ) that are functions of the wavelength λ defined by the following table (I) in the wavelength range of 400 nm to 700 nm. Functions obtained by normalizing each function determined by the product with respect to the incident angle θ ° so that the maximum value is 1 are _represented as CR _θ (λ), CG _θ (λ), and CB _θ (λ). In this specification, CR _θ (λ), CG _θ (λ), and CB _θ (λ) are also referred to as normalized spectral sensitivity functions. Stiles & Burch (1959) The function of wavelength λ obtained by normalizing the color matching functions defined in 10-deg, RCB CMFs so that the maximum value is 1, respectively, is r (λ), g (λ), and This is expressed as b (λ). In this specification, r (λ), g (λ), and b (λ) are also called normalized color matching functions. The wavelength λ that is a variable of CR _θ (λ), CG _θ (λ), and CB _θ (λ) is expressed as λ (n) = (Δλ × n + 400) nm as a function of n that is an integer of 0 or more. In this case, 9 in IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB defined by the following equations (1) to (3) for incident angles θ ° of 0 °, 30 °, and 40 °, respectively. The following table (II) shows the difference obtained by subtracting the minimum value from the maximum value of the three differences of IE _θ ^rR , IE _θ ^gG , and IE _θ ^{bB for} the same two incident angles θ °. Meet the conditions. Since the wavelength range mainly used for the evaluation of the optical filter is 400 nm to 700 nm, the value of Δλ is a positive constant that is a divisor of 300. In this specification, Δλ = 5. That is, the variable λ (n) is determined at 5 nm intervals. Even when Δλ is a constant other than 5, a function having a wavelength λ such as T _θ (λ) as a variable can be obtained by linear interpolation. The color matching function defined in Stiles & Burch (1959) 10-deg, RCB CMFs can be obtained from the Color & Vision Research Laboratory website (http://www.cvrl.org/).

  FIG. 2 shows graphs of R (λ), G (λ), and B (λ) shown in Table (I). The functions R (λ), G (λ), and B (λ) were determined as follows. First, ten types of commercially available color image sensors (hereinafter simply referred to as “image sensors”) were prepared. These image sensors were provided with image sensors such as CCD (Charge-Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor), and R (red), G (green) and B (blue) color filters. For each image sensor, spectral sensitivity characteristics corresponding to R, G, and B were disclosed as sensitivity spectra for each wavelength. For each image sensor, a color indicating a relatively largest value among the maximum value of the spectral sensitivity characteristic corresponding to R, the maximum value of the spectral sensitivity characteristic corresponding to G, and the maximum value of the spectral sensitivity characteristic corresponding to B. The filter (attribute) was selected. A coefficient is obtained so that the maximum value of the spectral sensitivity characteristic corresponding to the selected color filter is 1, and the coefficient is determined as a spectral sensitivity characteristic corresponding to R, a spectral sensitivity characteristic corresponding to G, and a spectral corresponding to B. The first normalization was performed by multiplying the sensitivity characteristic for each wavelength. These operations were performed on the spectral sensitivity characteristics of the 10 types of image sensors prepared, and the spectral sensitivity characteristics subjected to the first normalization were obtained. Next, for each of these ten types of spectral sensitivity characteristics that have been normalized, the spectral sensitivity characteristics corresponding to R, the spectral sensitivity characteristics corresponding to G, and the spectral sensitivity characteristics corresponding to B are respectively determined for each wavelength. Arithmetic averaging was performed to determine an average spectral sensitivity characteristic corresponding to each of R, G, and B. Further, a coefficient is obtained for each attribute of R, G, and B so that the maximum value of the average spectral sensitivity characteristic corresponding to each of R, G, and B is 1, and the coefficient is determined as R, G, and A second normalization is performed by multiplying the average spectral sensitivity characteristic corresponding to each of B for each wavelength, and functions R (λ), G (λ), and B (λ) are determined.

The normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) are the spectral transmittance T _θ (λ) of the optical filter 1a and the functions R (λ), G (λ), Alternatively, it is determined based on the product of B (λ). Specifically, with respect to the function obtained by the product of the spectral transmittance T _θ (λ) of the optical filter and the function R (λ) shown in Table (I) when the incident angle of light is θ °, the maximum A coefficient is obtained so that the value becomes 1, and a normalized spectral sensitivity function CR _θ (λ) is obtained by multiplying the coefficient by a function of a product of T _θ (λ) and R (λ) for each wavelength. Similarly, a normalized spectral sensitivity function CG _θ (λ) is obtained based on T _θ (λ) and G (λ), and a normalized spectral sensitivity function is calculated based on T _θ (λ) and B (λ). CB _θ (λ) is obtained. Here, the product of the spectral transmittance T _θ (λ) and other functions is obtained by multiplying them for each wavelength unless otherwise specified. For this reason, the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) are not only the characteristics of the optical filter 1a, but also the color filters provided in the image sensor mounted on the imaging device. It can be said that the function also takes into account the characteristics. The incident angle of the chief ray incident on the center of the image sensor or the image sensor is close to 0 °, and the incident angle of the chief ray incident on the periphery thereof is large. If an optical filter that changes the shape shift between the normalized color matching function curve and the normalized spectral sensitivity function curve depending on the angle of incidence of light on the optical filter is mounted, The hue changes when displaying or printing the generated image. For this reason, when displaying or printing an image photographed by the imaging device, the color of the subject, which should be the same color, changes from the central portion toward the peripheral portion, and can be recognized as uneven color. Compared to a region of the image corresponding to a change in the incident angle of light from 0 ° to 40 ° and a change in the incident angle of light from 0 ° to 30 °, it corresponds to a change in the incident angle of light from 30 ° to 40 °. The area of the image is narrow, and color unevenness is more easily recognized in this area. For this reason, even if the incident angle of the light to the optical filter changes, if the change in the shape of the curve of the normalized spectral sensitivity function is small, it is possible to prevent color unevenness from occurring in the image generated by the imaging device. Since the optical filter 1a satisfies the conditions shown in Table (II), even if the incident angle of light changes, the change in the shape of the curve of the normalized spectral sensitivity function is small, and the image pickup apparatus has such an optical filter 1a. By providing, it is possible to prevent color unevenness from occurring in an image generated by the imaging apparatus.

As shown in the equations (1) to (3), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB are differences obtained by subtracting the normalized spectral sensitivity function from the normalized color matching function in the wavelength range of 400 nm to 700 nm. It is determined by integrating. Therefore, by referring to IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB , the direction of deviation of the normalized spectral sensitivity function curve from the normalized color matching function curve can be determined. For example, when one of IE ₀ ^rR −IE ₃₀ ^rR and IE ₀ ^bB −IE ₃₀ ^bB is a positive value and the other is a negative value, IE ₀ ^rR −IE ₃₀ ^rR and IE ₀ ^bB −IE ₃₀ ^bB Color unevenness is more likely to occur than when both are positive. However, in the optical filter 1a, the range satisfies the conditions shown in Table (II), so that the image pickup apparatus includes such an optical filter 1a, thereby causing color unevenness in an image generated by the image pickup apparatus. Can be prevented.

When displaying or printing an image captured by an imaging device, corrections made to optimize brightness or color reproducibility are performed on a pixel-by-pixel basis, so the actual value of spectral sensitivity is directly corrected. It doesn't matter. Therefore, as described above, the normalized color matching functions r (λ), g (λ), and b (λ) and the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ ), The characteristics of the optical filter 1a can be appropriately specified by comparing the functions obtained by normalization. In addition, since the incident angle of the chief ray to each pixel of the image sensor can be predicted, it is conceivable to correct or display or print an image photographed by the imaging device according to the incident angle.

In the optical filter 1a, preferably 9 differences and IE 2 in IE _θ ^rR , IE _θ ^gG and IE _θ ^bB defined for the incident angles θ ° of 0 °, 30 ° and 40 ° respectively. A range which is a difference obtained by subtracting a minimum value from a maximum value of three differences of IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB with respect to two incident angles θ ° satisfies the condition shown in Table (III).

In the optical filter 1a, more preferably, nine differences in IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB defined for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively, and the same A range which is a difference obtained by subtracting a minimum value from a maximum value of three differences of IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB with respect to two incident angles θ ° satisfies the condition shown in Table (IV).

In the optical filter 1a, for example, IAE _θ ^rR , IAE _θ ^gG , and IAE defined with respect to incident angles θ ° of 0 °, 30 °, and 40 ° by the following formulas (4) to (6), respectively. _A range which is a difference obtained by subtracting a minimum value from a maximum value of three differences of IAE _θ ^rR , IAE _θ ^gG , and IAE _θ ^bB with _{respect to} nine differences in _θ ^bB and the same two incident angles θ ° is shown in Table (V). The condition shown in is satisfied.

As shown in the equations (4) to (6), IAE _θ ^rR , IAE _θ ^gG , and IAE _θ ^bB are the difference obtained by subtracting the normalized spectral sensitivity function from the normalized color matching function in the wavelength range of 400 nm to 700 nm. It is determined by integrating the absolute value. Only in the evaluation based on IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB , the integrated value in the wavelength band in which the difference obtained by subtracting the normalized spectral sensitivity function from the normalized color matching function is negative is positive. There is a possibility that it is canceled out by the integrated value in the wavelength band, and it may be difficult to appropriately specify the characteristics of the optical filter. However, when the optical filter 1a satisfies the conditions shown in Table (V), the change in the shape of the normalized spectral sensitivity function curve is small even when the incident angle of light changes more reliably, and the imaging apparatus By providing such an optical filter 1a, it is possible to more effectively prevent color unevenness from occurring in an image generated by the imaging apparatus. Thus, IAE _theta ^rR, can be evaluated more appropriately optical filter 1a with IAE _theta ^gG, and IAE _theta ^bB.

In the optical filter 1a, preferably nine differences and the same two in IAE _θ ^rR , IAE _θ ^gG and IAE _θ ^bB defined for incident angles θ ° of 0 °, 30 ° and 40 °, respectively. A range that is a difference obtained by subtracting the minimum value from the maximum value of the three differences of IAE _θ ^rR , IAE _θ ^gG , and IAE _θ ^bB for the two incident angles θ ° satisfies the condition shown in Table (VI).

In the optical filter 1a, for example, ISE _θ ^rR , ISE _θ ^gG , and ISE defined for the incident angles θ ° of 0 °, 30 °, and 40 ° by the following equations (7) to (9), respectively. nine difference and the same two incident angles ISE _theta ^rR for theta ° in _θ ^bB, ISE _θ ^gG, and range is the difference obtained by subtracting the minimum value from the maximum value of the three difference ISE _theta ^bB Table (VII) The condition shown in is further satisfied.

As shown in the equations (7) to (9), ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB are the difference obtained by subtracting the normalized spectral sensitivity function from the normalized color matching function in the wavelength range of 400 nm to 700 nm. It is determined by integrating the square value. As described above, it may be difficult to appropriately specify the characteristics of the optical filter only by evaluation based on IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB . However, if the optical filter 1a satisfies the conditions shown in Table (VII), the change in the shape of the normalized spectral sensitivity function curve is small even when the incident angle of light changes more reliably, and the imaging apparatus By providing such an optical filter 1a, it is possible to more effectively prevent color unevenness from occurring in an image generated by the imaging apparatus. As described above, the optical filter 1a can be more appropriately evaluated using ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB .

In the optical filter 1a, preferably nine differences and two identical ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB defined for incident angles θ ° of 0 °, 30 °, and 40 °, respectively. A range that is a difference obtained by subtracting the minimum value from the maximum value of the three differences of ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB with respect to two incident angles θ ° satisfies the condition shown in Table (VIII).

  The light absorbing agent contained in the light absorbing layer 10 absorbs at least part of light in the near infrared region, the optical filter 1a satisfies the above conditions (i) to (vii), and the table (II) As long as the conditions shown in (2) are satisfied, there is no particular limitation. The light absorber is formed of, for example, phosphonic acid and copper ions. In this case, the light absorption layer 10 can absorb light in a wide wavelength band of the near infrared region and the visible light region adjacent to the near infrared region. For this reason, even if the optical filter 1a is not provided with a reflective film, desired characteristics can be exhibited. Even when the optical filter 1a includes a reflection film, the optical filter 1a can be designed so that the wavelength band of the light beam reflected by the reflection film is sufficiently separated from the wavelength band of the light beam to be transmitted. For example, the wavelength band of the light beam reflected by the reflective film can be set to a wavelength band longer by 100 nm or more than the wavelength band of the transition region where the transmittance sharply decreases as the wavelength increases. Thereby, even if the incident angle of light is large and the wavelength band of the light beam reflected by the reflective film shifts to the short wavelength side, it overlaps with the wavelength band of the light beam absorbed by the light absorption layer 10, and the transition of the optical filter 1a The transmittance characteristics in the region are unlikely to fluctuate with changes in the incident angle of light. In addition, the light absorption layer 10 can absorb light in a wide range of wavelength bands in the ultraviolet region.

  When the light absorption layer 10 includes a light absorber formed by phosphonic acid and copper ions, the phosphonic acid includes, for example, a first phosphonic acid having an aryl group. In the first phosphonic acid, the aryl group is bonded to the phosphorus atom. Accordingly, the above condition is easily satisfied in the optical filter 1a.

  The aryl group of the first phosphonic acid is, for example, a phenyl group, a benzyl group, a toluyl group, a nitrophenyl group, a hydroxyphenyl group, a halogenated phenyl group in which at least one hydrogen atom in the phenyl group is substituted with a halogen atom, Alternatively, it is a halogenated benzyl group in which at least one hydrogen atom in the benzene ring of the benzyl group is substituted with a halogen atom.

  When the light absorption layer 10 includes a light absorber formed by phosphonic acid and copper ions, the phosphonic acid desirably further includes a second phosphonic acid having an alkyl group. In the second phosphonic acid, the alkyl group is bonded to the phosphorus atom.

  The alkyl group that the second phosphonic acid has is, for example, an alkyl group having 6 or less carbon atoms. This alkyl group may have either a straight chain or a branched chain.

  When the light absorption layer 10 includes a light absorber formed of phosphonic acid and copper ions, the light absorption layer 10 desirably further includes a phosphate ester that disperses the light absorber and a matrix resin.

The phosphoric acid ester contained in the light absorption layer 10 is not particularly limited as long as the light absorber can be appropriately dispersed. For example, the phosphoric acid diester represented by the following formula (c1) and the following formula (c2) At least one of phosphoric acid monoesters. In the following formulas (c1) and (c2), R ₂₁ , R ₂₂ , and R ₃ are each a monovalent functional group represented by — (CH ₂ CH ₂ O) nR ₄ , and n is , 1 to 25, and R ₄ represents an alkyl group having 6 to 25 carbon atoms. R ₂₁ , R ₂₂ , and R ₃ are the same or different types of functional groups.

  The phosphate ester is not particularly limited. For example, 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 Or Plysurf A215C: Polyoxyethylene tridecyl ether phosphate. These are all products manufactured by Daiichi Kogyo Seiyaku. Further, the phosphate ester is 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. possible. These are all products manufactured by Nikko Chemicals.

  The matrix resin contained in the light absorption layer 10 is, for example, a resin that can disperse a light absorber and can be cured by heat or ultraviolet light. Furthermore, when a resin layer of 0.1 mm is formed with the resin as the matrix resin, the transmittance of the resin layer with respect to light having a wavelength of 350 nm to 900 nm is, for example, 80% or more, preferably 85% or more, More preferably, a resin of 90% or more can be used, but is not particularly limited as long as the conditions (i) to (vii) and the conditions shown in Table (II) are satisfied in the optical filter 1a. The content of phosphonic acid in the light absorption layer 10 is, for example, 3 to 180 parts by mass with respect to 100 parts by mass of the matrix resin.

  The matrix resin contained in the light absorbing layer 10 is not particularly limited as long as the above properties are satisfied. For example, (poly) olefin resin, polyimide resin, polyvinyl butyral resin, polycarbonate resin, polyamide resin, polysulfone resin, polyethersulfone Resin, polyamideimide resin, (modified) acrylic resin, epoxy resin, or silicone resin. The matrix resin may contain an aryl group such as a phenyl group, and is preferably a silicone resin containing an aryl group such as a phenyl group. If the light absorption layer 10 is hard (rigid), cracks are likely to occur due to curing shrinkage during the manufacturing process of the optical filter 1a as the thickness of the light absorption layer 10 increases. When the matrix resin is a silicone resin containing an aryl group, the light absorption layer 10 tends to have good crack resistance. In addition, when a silicone resin containing an aryl group is used, the light absorbent hardly aggregates when it contains a light absorbent formed by the above-described phosphonic acid and copper ions. Furthermore, when the matrix resin of the light absorption layer 10 is a silicone resin containing an aryl group, the phosphate ester contained in the light absorption layer 10 is a phosphate ester represented by the formula (c1) or the formula (c2). It is desirable to have a linear organic functional group having flexibility such as an oxyalkyl group. Because of the interaction based on the combination of the above-mentioned phosphonic acid, a silicone resin containing an aryl group, and a phosphate ester having a linear organic functional group such as an oxyalkyl group, the light absorber is difficult to aggregate, and This is because the light absorption layer can be provided with good rigidity and good flexibility. Specific examples of the silicone resin used as the matrix resin include KR-255, KR-300, KR-2621-1, KR-211, KR-311, KR-216, KR-212, and KR-251. be able to. These are all silicone resins manufactured by Shin-Etsu Chemical Co., Ltd.

  As shown in FIG. 1A, the optical filter 1a further includes a transparent dielectric substrate 20, for example. One main surface of the transparent dielectric substrate 20 is covered with the light absorption layer 10. The characteristics of the transparent dielectric substrate 20 are not particularly limited as long as the conditions (i) to (vii) and the conditions shown in Table (II) are satisfied in the optical filter 1a. The transparent dielectric substrate 20 is a dielectric substrate having a high average transmittance (for example, 80% or more, preferably 85% or more, more preferably 90% or more) at 450 nm to 600 nm, for example.

  The transparent dielectric substrate 20 is made of, for example, glass or resin. When the transparent dielectric substrate 20 is made of glass, the glass contains, for example, borosilicate glass such as D263T eco, soda lime glass (blue plate), white plate glass such as B270, non-alkali glass, or copper. Infrared absorbing glass such as phosphate glass or fluorophosphate glass containing copper. When the transparent dielectric substrate 20 is an infrared-absorbing glass such as a phosphate glass containing copper or a fluorophosphate glass containing copper, the infrared-absorbing performance and light of the transparent dielectric substrate 20 A desired infrared absorption performance can be provided to the optical filter 1a by a combination with the infrared absorption performance of the absorption layer 10. Such infrared absorbing glass is, for example, BG-60, BG-61, BG-62, BG-63, or BG-67 manufactured by Schott, 500EXL manufactured by Nippon Electric Glass, or HOYA. CM5000, CM500, C5000, or C500S manufactured by the company. Further, the transparent dielectric substrate 20 may have an ultraviolet absorption characteristic.

  The transparent dielectric substrate 20 may be a crystalline substrate having transparency such as magnesium oxide, sapphire, or quartz. For example, since sapphire has high hardness, it is hard to be damaged. For this reason, the plate-like sapphire is placed on the front surface of a camera module or lens provided in a mobile terminal such as a smartphone or a mobile phone as a scratch-resistant protective material (sometimes called a protect filter or a cover glass). May be. By forming the light absorption layer 10 on such a plate-like sapphire, light with a wavelength of 650 nm to 1100 nm can be effectively cut along with protection of the camera module and the lens. There is no need to arrange an optical filter having an infrared shielding property with a wavelength of 650 nm to 1100 nm around an imaging device such as a CCD (Charge-Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor or inside a camera module. For this reason, if the light absorption layer 10 is formed on plate-shaped sapphire, it can contribute to the low profile of a camera module or an imaging device.

  When the transparent dielectric substrate 20 is made of resin, the resin is, for example, (poly) olefin resin, polyimide resin, polyvinyl butyral resin, polycarbonate resin, polyamide resin, polysulfone resin, polyethersulfone resin, polyamideimide resin, (Modified) An acrylic resin, an epoxy resin, or a silicone resin.

  The optical filter 1a can be manufactured, for example, by applying a coating liquid for forming the light absorption layer 10 to one main surface of the transparent dielectric substrate 20, forming a coating film, and drying the coating film. The method for preparing the coating liquid and the method for producing the optical filter 1a will be described by taking as an example the case where the light absorption layer 10 contains a light absorber formed of phosphonic acid and copper ions.

  First, an example of a method for preparing a coating solution will be described. A copper salt such as copper acetate monohydrate is added to a predetermined solvent such as tetrahydrofuran (THF) and stirred to obtain a copper salt solution. Next, a phosphoric acid ester compound such as a phosphoric acid diester represented by the formula (c1) or a phosphoric acid monoester represented by the formula (c2) is added to the solution of the copper salt and stirred to prepare a solution A. To do. Also, the first phosphonic acid is added to a predetermined solvent such as THF and stirred to prepare a liquid B. Next, while stirring the liquid A, the liquid B is added to the liquid A and stirred for a predetermined time. Next, a predetermined solvent such as toluene is added to this solution and stirred to obtain liquid C. Next, desolvation treatment is performed for a predetermined time while heating the C liquid to obtain the D liquid. Thereby, components generated by dissociation of a solvent such as THF and a copper salt such as acetic acid (boiling point: about 118 ° C.) are removed, and a light absorber is generated by the first phosphonic acid and copper ions. The temperature at which the liquid C is heated is determined based on the boiling point of the component to be removed that has dissociated from the copper salt. In the solvent removal treatment, a solvent such as toluene (boiling point: about 110 ° C.) used for obtaining the liquid C is also volatilized. Since it is desirable for this solvent to remain to some extent in the coating solution, the amount of solvent added and the time for desolvation treatment should be determined from this viewpoint. In addition, in order to obtain C liquid, it can replace with toluene and can use o-xylene (boiling point: about 144 degreeC). In this case, since the boiling point of o-xylene is higher than that of toluene, the addition amount can be reduced to about one-fourth of the addition amount of toluene. A coating solution can be prepared by adding a matrix resin such as a silicone resin to the solution D and stirring.

  The coating liquid is applied to one main surface of the transparent dielectric substrate 20 to form a coating film. For example, the coating liquid is applied to one main surface of the transparent dielectric substrate 20 by die coating, spin coating, or application by a dispenser to form a coating film. Next, the coating film is cured by performing a predetermined heat treatment on the coating film. For example, the coating film is exposed to an environment having a temperature of 50 ° C. to 200 ° C. for a predetermined time.

  In the optical filter 1a, the light absorption layer 10 may be formed as a single layer or may be formed as a plurality of layers. When the light absorption layer 10 is formed as a plurality of layers, the light absorption layer 10 includes, for example, a first layer containing a light absorber formed by first phosphonic acid and copper ions, and a second layer. And a second layer containing a light absorber formed by phosphonic acid and copper ions. In this case, the coating liquid for forming the first layer can be prepared as described above. On the other hand, the second layer is formed using a coating liquid prepared separately from the coating liquid for forming the first layer. The coating liquid for forming the second layer can be prepared, for example, as follows.

  A copper salt such as copper acetate monohydrate is added to a predetermined solvent such as tetrahydrofuran (THF) and stirred to obtain a copper salt solution. Next, a phosphoric acid ester compound such as a phosphoric acid diester represented by the formula (c1) or a phosphoric acid monoester represented by the formula (c2) is added to the copper salt solution and stirred to prepare a solution E. To do. Further, the second phosphonic acid is added to a predetermined solvent such as THF and stirred to prepare a solution F. Next, while stirring the E liquid, the F liquid is added to the E liquid and stirred for a predetermined time. Next, a predetermined solvent such as toluene is added to the solution and stirred, and the solvent is further volatilized to obtain a liquid G. Next, a matrix resin such as a silicone resin is added to the G liquid and stirred to obtain a coating liquid for forming the second layer.

A coating solution for forming the first layer and a coating solution for forming the second layer are applied to form a coating film, and the coating film is subjected to a predetermined heat treatment to cure the coating film. Thus, the first layer and the second layer can be formed. For example, the coating film is exposed to an environment having a temperature of 50 ° C. to 200 ° C. for a predetermined time. The order in which the first layer and the second layer are formed is not particularly limited, and the first layer and the second layer may be formed in different periods or may be formed in the same period. A protective layer may be formed between the first layer and the second layer. The protective layer is formed of, for example, a SiO ₂ vapor deposition film.

<Modification>
The optical filter 1a can be changed from various viewpoints. For example, the optical filter 1a may be changed to the optical filters 1b to 1f shown in FIGS. 1B to 1F, respectively. The optical filters 1b to 1f are configured in the same manner as the optical filter 1a unless otherwise described. Constituent elements of the optical filters 1b to 1f that are the same as or correspond to the constituent elements of the optical filter 1a are assigned the same reference numerals, and detailed descriptions thereof are omitted. The description regarding the optical filter 1a also applies to the optical filters 1b to 1f unless there is a technical contradiction.

  As shown in FIG. 1B, in the optical filter 1b, the light absorption layers 10 are formed on both main surfaces of the transparent dielectric substrate 20. Accordingly, the conditions (i) to (vii) and the conditions shown in Table (II) are satisfied not by the single light absorption layer 10 but by the two light absorption layers 10. The thickness of the light absorption layer 10 on both main surfaces of the transparent dielectric substrate 20 may be the same or different. That is, the light absorption layer is formed on both main surfaces of the transparent dielectric substrate 20 so that the thickness of the light absorption layer 10 necessary for the optical filter 1b to obtain desired optical characteristics is evenly or unevenly distributed. 10 is formed. Thereby, the thickness of each light absorption layer 10 formed on one main surface of the transparent dielectric substrate 20 of the optical filter 1b is smaller than that of the optical filter 1a. Since the light absorption layers 10 are formed on both main surfaces of the transparent dielectric substrate 20, even when the transparent dielectric substrate 20 is thin, warpage is suppressed in the optical filter 1b. Each of the two light absorption layers 10 may be formed as a plurality of layers.

As shown in FIG. 1C, in the optical filter 1c, the light absorption layers 10 are formed on both main surfaces of the transparent dielectric substrate 20. In addition, the optical filter 1 c includes an antireflection film 30. The antireflection film 30 is a film that is formed so as to form an interface between the optical filter 1c and the air and reduces reflection of light in the visible light region. The antireflection film 30 is a film formed of a dielectric material such as resin, oxide, and fluoride. The antireflection film 30 may be a multilayer film formed by laminating two or more kinds of dielectrics having different refractive indexes. In particular, the antireflection film 30 may be a dielectric multilayer film made of a low refractive index material such as SiO ₂ and a high refractive index material such as TiO ₂ or Ta ₂ O ₅ . In this case, Fresnel reflection at the interface between the optical filter 1c and air is reduced, and the amount of light in the visible light region of the optical filter 1c can be increased. The antireflection film 30 may be formed on both surfaces of the optical filter 1c, or may be formed on one surface of the optical filter 1c.

As shown in FIG. 1D, in the optical filter 1d, the light absorption layers 10 are formed on both main surfaces of the transparent dielectric substrate 20. In addition, the optical filter 1 d further includes a reflective film 40. The reflective film 40 reflects infrared rays and / or ultraviolet rays. The reflective film 40 is, for example, a film formed by vapor deposition of a metal such as aluminum, or a dielectric multilayer film in which layers made of a high refractive index material and layers made of a low refractive index material are alternately laminated. is there. As the high refractive index material _{TiO 2, ZrO 2, Ta 2} O 5, Nb 2 O 5, ZnO, and In ₂ O ₃ material having a refractive index of 1.7 to 2.5, such as are used. As the low refractive index material, a material having a refractive index of 1.2 to 1.6 such as SiO ₂ , Al ₂ O ₃ , and MgF ₂ is used. A method for forming the dielectric multilayer film is, for example, a chemical vapor deposition (CVD) method, a sputtering method, or a vacuum deposition method. Further, such a reflective film may be formed so as to form both main surfaces of the optical filter (not shown). When reflective films are formed on both main surfaces of the optical filter, the stress is balanced on both the front and back surfaces of the optical filter, so that the optical filter is less likely to warp.

  As shown in FIG. 1E, the optical filter 1e is constituted only by the light absorption layer 10. The optical filter 1e is formed, for example, by applying a coating liquid to a predetermined substrate such as a glass substrate, a resin substrate, or a metal substrate (for example, a steel substrate or a stainless steel substrate) to form a coating film, and then curing the coating film. It can manufacture by making it peel from a board | substrate. The optical filter 1e may be manufactured by a casting method. The optical filter 1e is thin because it does not include the transparent dielectric substrate 20. For this reason, the optical filter 1e can contribute to the reduction in the height of the imaging device.

  As shown in FIG. 1F, the optical filter 1f includes a light absorption layer 10 and a pair of antireflection films 30 disposed on both surfaces thereof. In this case, the optical filter 1f can contribute to a reduction in the height of the imaging device and can increase the amount of light in the visible light region as compared to the optical filter 1e.

  Each of the optical filters 1a to 1f may be changed to include an infrared absorption layer (not shown) separately from the light absorption layer 10 as necessary. The infrared absorption layer contains, for example, an infrared absorber made of an organic infrared absorber or a metal complex such as cyanine, phthalocyanine, squarylium, diimmonium, and azo. The infrared absorption layer contains, for example, one or more infrared absorbers selected from these infrared absorbers. This organic infrared absorber has a small wavelength range (absorption band) of light that can be absorbed, and is suitable for absorbing light in a specific range of wavelengths.

  Each of the optical filters 1a to 1f may be changed to include an ultraviolet absorbing layer (not shown) separately from the light absorbing layer 10 as necessary. The ultraviolet absorbing layer contains, for example, ultraviolet absorbers such as benzophenone, triazine, indole, merocyanine, and oxazole. The ultraviolet absorbing layer contains, for example, one or more ultraviolet absorbers selected from these ultraviolet absorbers. These ultraviolet absorbers include, for example, those that absorb ultraviolet rays in the vicinity of 300 nm to 340 nm, emit light having a wavelength longer than the absorbed wavelength (fluorescence), and function as a fluorescent agent or fluorescent whitening agent. The ultraviolet absorbing layer can reduce the incidence of ultraviolet rays that cause deterioration of materials used for optical filters such as resins.

  The above infrared absorber and / or ultraviolet absorber may be preliminarily contained in the resin-made transparent dielectric substrate 20 to form a substrate having the characteristic of absorbing infrared rays and / or ultraviolet rays. In this case, the resin needs to be able to appropriately dissolve or disperse the infrared absorber and / or the ultraviolet absorber and be transparent. Such resins include (poly) olefin resins, polyimide resins, polyvinyl butyral resins, polycarbonate resins, polyamide resins, polysulfone resins, polyethersulfone resins, polyamideimide resins, (modified) acrylic resins, epoxy resins, and silicone resins. Can be illustrated

  As shown in FIG. 3, the optical filter 1 a is used, for example, for manufacturing the imaging device 100 (camera module). The imaging apparatus 100 includes a lens system 2, an imaging element 4, a color filter 3, and an optical filter 1a. The image sensor 4 receives light that has passed through the lens system 2. The color filter 3 is disposed in front of the image sensor 4 and includes three color filters of R (red), G (green), and B (blue). The optical filter 1 a is disposed in front of the color filter 3. In particular, the light absorption layer 10 is formed in contact with the surface of the transparent dielectric substrate 20 close to the lens system 2. As described above, by using a material with high hardness such as sapphire for the transparent dielectric substrate 20, the effect of protecting the lens system 2 or the image sensor 4 is increased. For example, three color filters of R (red), G (green), and B (blue) in the color filter 3 are arranged in a matrix, and R (red), A filter of any color of G (green) and B (blue) is arranged. The image sensor 4 receives light from the subject that has passed through the lens system 2, the optical filter 1 a, and the color filter 3. The imaging device 100 generates an image based on information about charges generated by light received by the imaging element 4. The color filter 3 and the image sensor 4 may be integrated to form a color image sensor.

  In the optical filter 1a, the above conditions (i) to (vii) and the conditions shown in Table (II) are satisfied. Therefore, the imaging apparatus 100 including such an optical filter 1a displays an image in which color unevenness is prevented. Can be generated.

  The examples illustrate the invention in more detail. The present invention is not limited to the following examples.

<Transmission spectrum measurement>
A transmittance spectrum when light having a wavelength of 300 nm to 1200 nm is incident on an optical filter according to Examples and Comparative Examples, a semi-finished product thereof, or a laminate according to a reference example, an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, Product name: V-670). When incident angles of incident light are set to 0 °, 30 °, and 40 ° with respect to the optical filters of Examples and Comparative Examples, some semi-finished products, and some laminates according to some reference examples The transmittance spectrum of was measured. With respect to the laminates according to other semi-finished products and other reference examples, transmittance spectra were measured when the incident angle of incident light was set to 0 °.

<Example 1>
Coating liquid IRA1 was prepared as follows. 1.1 g of copper acetate monohydrate and 60 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours, and phosphate ester (product name: Prisurf A208F, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to the resulting liquid. 3 g was added and stirred for 30 minutes to obtain Liquid A. 10 g of THF was added to 0.6 g of phenylphosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and stirred for 30 minutes to obtain a liquid B. B liquid was added while stirring A liquid, and it stirred at room temperature for 1 minute. After 45 g of toluene was added to this solution, the mixture was stirred at room temperature for 1 minute to obtain solution C. While heating with an oil bath (manufactured by Tokyo Rika Kikai Co., Ltd., model: OSB-2100) adjusted to 120 ° C. by putting C liquid into a flask, The solvent was removed for 25 minutes to obtain a solution D. Liquid D was taken out from the flask, 4.4 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300) was added, and the mixture was stirred at room temperature for 30 minutes to obtain a coating liquid IRA1.

  A coating solution IRA2 was prepared as follows. 2.25 g of copper acetate monohydrate and 120 g of tetrahydrofuran (THF) were mixed and stirred for 3 hours, and 1.8 g of phosphate ester (Daiichi Kogyo Seiyaku product name: Prisurf A208F) was added to the resulting liquid. And stirred for 30 minutes to obtain solution E. 20 g of THF was added to 1.35 g of butylphosphonic acid and stirred for 30 minutes to obtain a liquid F. F solution was added while stirring E solution, and after stirring at room temperature for 3 hours, 40 g of toluene was added, and then the solvent was volatilized in an environment of 85 ° C. over 7.5 hours to obtain G solution. 8.8 g of silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR-300) was added to solution G and stirred for 3 hours to obtain coating solution IRA2.

The coating liquid IRA1 was applied to one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) with a die coater, and the oven was 85 ° C. for 3 hours, then 125 ° C. for 3 hours, and then 150 ° C. Heat treatment was performed for 1 hour and then at 170 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. In this manner, a semi-finished product α of the optical filter according to Example 1 was obtained. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.2 mm. The transmittance spectrum of the semi-finished product α at an incident angle of 0 ° is shown in FIG. 4A. The semi-finished product α had the following characteristics (α1) to (α6).
(Α1): The average transmittance at a wavelength of 700 to 1000 nm was 0.5% or less.
(Α2): The average transmittance at a wavelength of 1100 to 1200 nm was 29.5%.
(Α3): The average transmittance at a wavelength of 450 to 600 nm was 88.0%.
(Α4): The transmittance at a wavelength of 400 nm was 63.7%.
(Α5): When the IR cutoff wavelength is 632 nm, the UV cutoff wavelength is 394 nm, and the difference between the IR cutoff wavelength and the UV cutoff wavelength is regarded as the full width at half maximum of the transmission region, the half value of the transmission region The total width was 238 nm.
(Α6): The wavelength at which the spectral transmittance was 20% at a wavelength of 600 to 800 nm was 661 nm.

A vapor-deposited film of SiO ₂ (protective layer p1) having a thickness of 500 nm was formed on the infrared absorption layer ira11 of the semi-finished product α using a vacuum vapor deposition apparatus. Similarly, a deposited film (protective layer p2) of SiO _{2 having} a thickness of 500 nm was formed on the infrared absorption layer ira12 of the semi-finished product α. The coating liquid IRA2 is applied to the surface of the protective layer p1 by a die coater, and is heated in an oven at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 ° C. for 3 hours. The coating film was cured to form an infrared absorption layer ira21. Also, the coating liquid IRA2 was applied to the surface of the protective layer p2 with a die coater, and the coating film was cured under the same heating conditions to form the infrared absorption layer ira22. In this way, a semi-finished product β was obtained. The total thickness of the infrared absorption layer ira21 and the infrared absorption layer ira22 was 50 μm. The transmittance spectrum of the semi-finished product β is shown in FIG. 4B. The semi-finished product β had the following characteristics (β1) to (β6).
(Β1): The average transmittance at a wavelength of 700 to 1000 nm was 0.5% or less.
(Β2): Average transmittance at a wavelength of 1100 to 1200 nm was 4.5%.
(Β3): The average transmittance at a wavelength of 450 to 600 nm was 86.9%.
(Β4): The transmittance at a wavelength of 400 nm was 62.1%.
(Β5): The IR cutoff wavelength was 631 nm, the UV cutoff wavelength was 394 nm, and the full width at half maximum of the transmission region was 237 nm.
(Β6): The wavelength with a spectral transmittance of 20% at a wavelength of 600 to 800 nm was 659 nm.

A vapor-deposited film of SiO ₂ (protective layer p3) having a thickness of 500 nm was formed on the infrared absorption layer ira22 of the semi-finished product β using a vacuum vapor deposition apparatus.

The coating solution UVA1 was adjusted as follows. As the ultraviolet absorbing material, a benzophenone-based ultraviolet absorbing material that absorbs little light in the visible light region and is soluble in MEK (methyl ethyl ketone) was used. This ultraviolet absorbing material was dissolved in MEK as a solvent, and polyvinyl butyral (PVB) having a solid content of 60% by weight was added and stirred for 2 hours to obtain a coating solution UVA1. The coating liquid UVA1 was applied onto the protective layer p3 by spin coating, and was heated and cured at 140 ° C. for 30 minutes to form the ultraviolet absorbing layer uva1. The thickness of the ultraviolet absorbing layer uva1 was 6 μm. Separately, an ultraviolet absorbing layer having a thickness of 6 μm was formed on the surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) by spin coating using the coating liquid UVA1, and the laminate according to Reference Example 1 was obtained. The transmittance spectrum of the laminate according to Reference Example 1 is shown in FIG. 4C. The laminate according to Reference Example 1 had the following characteristics (r1) to (r3).
(R1): The transmittance at a wavelength of 350 to 390 nm was 0.5% or less.
(R2): The transmittance at a wavelength of 400 nm is 12.9%, the transmittance at 410 nm is 51.8%, the transmittance at 420 nm is 77.1%, and the transmittance at 450 nm is 89.8%. Met.
(R3): The average transmittance at a wavelength of 450 to 750 nm was 91.0%.

An antireflection film ar1 was formed on the infrared absorption layer ira21 using a vacuum deposition apparatus. Further, an antireflection film ar2 was formed on the ultraviolet absorbing layer uva1 using a vacuum deposition apparatus. The antireflection film ar1 and the antireflection film ar2 have the same specifications and are films in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar1 and the antireflection film ar2 have seven layers. The layer and total film thickness was about 0.4 μm. In this way, an optical filter according to Example 1 was obtained. An antireflection film was formed on one surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) under the same conditions as the formation of the antireflection film ar1, and a laminate according to Reference Example 2 was obtained. The transmittance spectrum of the laminate according to Reference Example 2 is shown in FIG. 4D. The laminate according to Reference Example 2 had the following characteristics (s1) to (s4).
(S1): When the incident angle of light is 0 °, the transmittance at a wavelength of 350 nm is 73.4%, the transmittance at a wavelength of 380 nm is 88.9%, and the transmittance at a wavelength of 400 nm is 95.%. The average transmittance at a wavelength of 400 to 700 nm was 95.3%, and the transmittance at a wavelength of 715 nm was 95.7%.
(S2): When the incident angle of light is 30 °, the transmittance at a wavelength of 350 nm is 78.5%, the transmittance at a wavelength of 380 nm is 92.0%, and the transmittance at a wavelength of 400 nm is 94. The average transmittance at a wavelength of 400 to 700 nm was 94.3%, and the transmittance at a wavelength of 715 nm was 94.6%.
(S3): When the incident angle of light is 40 °, the transmittance at a wavelength of 350 nm is 82.3%, the transmittance at a wavelength of 380 nm is 93.3%, and the transmittance at a wavelength of 400 nm is 94.3%. The average transmittance at a wavelength of 400 to 700 nm was 94.0%, and the transmittance at a wavelength of 715 nm was 94.1%.
(S4): Regardless of the incident angle of light, there was no wavelength band that caused a ripple in which the transmittance locally decreased at a wavelength of 400 to 700 nm.

The transmittance spectrum of the optical filter according to Example 1 is shown in FIG. Further, the optical filter according to Example 1 had the characteristics shown in Table 12. For each of cases where the incident angle θ of light is 0 °, 30 °, and 40 °, the spectral transmittance T _θ (λ) of the optical filter according to Example 1 and the function R (λ) shown in Table (I) The normalized spectral sensitivity function CR _θ (λ) was obtained by normalizing the function obtained by the product of 1 and 2 so that the maximum value is 1. FIG. 5A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). The function obtained by the product of the spectral transmittance T _θ (λ) of the optical filter according to the first embodiment and the function G (λ) shown in Table (I) is normalized so that the maximum value is 1. Thus, the normalized spectral sensitivity function CG _θ (λ) was obtained. FIG. 5B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). The function obtained by the product of the spectral transmittance T _θ (λ) of the optical filter according to the first embodiment and the function B (λ) shown in Table (I) is normalized so that the maximum value is 1. Thus, the normalized spectral sensitivity function CB _θ (λ) was obtained. FIG. 5C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Tables 13-15.

<Example 2>
Coating liquid IRA1 and coating liquid IRA2 were prepared in the same manner as in Example 1. The coating liquid IRA1 was applied to one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) with a die coater, and the oven was 85 ° C. for 3 hours, then 125 ° C. for 3 hours, and then 150 ° C. Heat treatment was performed for 1 hour and then at 170 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.2 mm.

A deposited film (protective layer p1) of SiO _{2 having} a thickness of 500 nm was formed on the infrared absorption layer ira11 using a vacuum deposition apparatus. Similarly, a deposited SiO ₂ film (protective layer p2) having a thickness of 500 nm was formed on the infrared absorption layer ira12. The coating liquid IRA2 is applied to the surface of the protective layer p1 by a die coater, and is heated in an oven at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 ° C. for 3 hours. The coating film was cured to form an infrared absorption layer ira21. Also, the coating liquid IRA2 was applied to the surface of the protective layer p2 with a die coater, and the coating film was cured under the same heating conditions to form the infrared absorption layer ira22. The total thickness of the infrared absorption layer ira21 and the infrared absorption layer ira22 was 50 μm.

A 500 nm thick SiO ₂ vapor deposition film (protective layer p3) was formed on the infrared absorption layer ira22 using a vacuum vapor deposition apparatus. A coating solution UVIRA1 containing an infrared absorbing dye and an ultraviolet absorbing dye was prepared as follows. The infrared absorbing dye was a combination of a cyanine organic dye and a squarylium organic dye having an absorption peak at a wavelength of 680 to 780 nm and hardly absorbing light in the visible light region. The ultraviolet absorbing dye was a dye made of a benzophenone ultraviolet absorbing substance that hardly absorbs light in the visible light region. The infrared absorbing dye and the ultraviolet absorbing dye were soluble in MEK. An infrared absorbing dye and an ultraviolet absorbing dye were added to MEK as a solvent, PVB as a matrix material was further added, and then stirred for 2 hours to obtain a coating solution UVIRA1. The blending ratio of the infrared absorbing dye and the blending ratio of the ultraviolet absorbing dye in the coating liquid UVIRA1 were determined so that the laminate according to Reference Example 3 showed the transmittance spectrum shown in FIG. 6A. The laminate according to Reference Example 3 was applied by coating the coating solution UVIRA1 on a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) by spin coating, and then the coating film was cured by heating at 140 ° C. for 30 minutes. Made. In the coating solution UVIRA1, the mass ratio of the infrared absorbing dye to the solid content of PVB (the weight of the infrared absorbing dye: the mass of the solid content of PVB) was about 1: 199. Further, the mass ratio of the ultraviolet absorbing dye and the solid content of PVB (the mass of the ultraviolet absorbing dye: the mass of the solid content of PVB) was about 40:60. The laminate according to Reference Example 3 had the following characteristics (t1) to (t5).
(T1): The transmittance at a wavelength of 700 nm was 8.7%, the transmittance at a wavelength of 715 nm was 13.6%, and the average transmittance at a wavelength of 700 to 800 nm was 66.2%.
(T2): The transmittance at a wavelength of 1100 nm was 92.1%.
(T3): The transmittance at a wavelength of 400 nm was 11.8%, the transmittance at 450 nm was 85.3%, and the average transmittance at a wavelength of 500 to 600 nm was 89.1%.
(T4): The IR cutoff wavelength at a wavelength of 600 nm to 700 nm was 669 nm, the IR cutoff wavelength at a wavelength of 700 nm to 800 nm was 729 nm, and the difference between them was 60 nm. The wavelength (maximum absorption wavelength) showing the lowest transmittance at wavelengths of 600 nm to 800 nm was 705 nm.
(T5): The UV cutoff wavelength at a wavelength of 350 nm to 450 nm was 411 nm.

  The coating liquid UVIRA1 was applied on the protective layer p3 by spin coating, and the coating film was cured by heating at 140 ° C. for 30 minutes to form an infrared / ultraviolet absorbing layer uvira1. The thickness of the infrared / ultraviolet absorbing layer uvira1 was 7 μm.

An antireflection film ar1 was formed on the infrared absorption layer ira21 using a vacuum deposition apparatus. Further, an antireflection film ar2 was formed on the infrared / ultraviolet absorption layer uvira1 by using a vacuum deposition apparatus. The antireflection film ar1 and the antireflection film ar2 have the same specifications and are films in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar1 and the antireflection film ar2 have seven layers. The layer and total film thickness was about 0.4 μm. In this way, an optical filter according to Example 2 was obtained.

The transmittance spectrum of the optical filter according to Example 2 is shown in FIG. 6B and Table 16. Further, the optical filter according to Example 2 had the characteristics shown in Table 17. In the same manner as in the first embodiment, the spectral transmittances T _θ (λ) and R (of the optical filter according to the second embodiment for the cases where the incident angles θ of light are 0 °, 30 °, and 40 °, respectively. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 7A shows a graph of the normalized color matching function r (λ) and CR _θ (λ). FIG. 7B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 7C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 18 to Table 20.

<Example 3>
Coating liquid IRA1 and coating liquid IRA2 were prepared in the same manner as in Example 1. The coating liquid IRA1 was applied to one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) with a die coater, and the oven was 85 ° C. for 3 hours, then 125 ° C. for 3 hours, and then 150 ° C. Heat treatment was performed for 1 hour and then at 170 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. Thus, a semi-finished product γ of the optical filter according to Example 3 was obtained. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.2 mm. The transmittance spectrum of the semi-finished product γ at an incident angle of 0 ° is shown in FIG. 8A. The semi-finished product γ had the following characteristics (γ1) to (γ6).
(Γ1): The average transmittance at a wavelength of 700 to 1000 nm was 0.5% or less.
(Γ2): The average transmittance at a wavelength of 1100 to 1200 nm was 25.9%.
(Γ3): The average transmittance at a wavelength of 450 to 600 nm was 87.5%.
(Γ4): The transmittance at a wavelength of 400 nm was 60.9%.
(Γ5): IR cutoff wavelength was 629 nm, UV cutoff wavelength was 395 nm, and the full width at half maximum of the transmission region was 234 nm.
(Γ6): The wavelength at a spectral transmittance of 20% at a wavelength of 600 to 800 nm was 657 nm.

An SiO ₂ vapor deposition film (protective layer p2) having a thickness of 500 nm was formed on the infrared absorption layer ira12 of the semi-finished product γ. On the protective layer p2, the coating solution UVA1 used in Example 1 was applied by spin coating, and the coating film was heated and cured at 140 ° C. for 30 minutes to form an ultraviolet absorbing layer uva1. The thickness of the ultraviolet absorbing layer uva1 was 6 μm.

An antireflection film ar1 was formed on the infrared absorption layer ira11 using a vacuum deposition apparatus. Further, an antireflection film ar2 was formed on the ultraviolet absorbing layer uva1 using a vacuum deposition apparatus. The antireflection film ar1 and the antireflection film ar2 have the same specifications and are films in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar1 and the antireflection film ar2 have seven layers. The layer and total film thickness was about 0.4 μm. In this way, an optical filter according to Example 3 was obtained.

The transmittance spectrum of the optical filter according to Example 3 is shown in FIG. 8B and Table 21. The optical filter according to Example 3 had the characteristics shown in Table 22. In the same manner as in the first embodiment, the spectral transmittances T _θ (λ) and R (of the optical filter according to the third embodiment for each of the cases where the incident angles θ of light are 0 °, 30 °, and 40 °. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 9A shows a graph of the normalized color matching function r (λ) and CR _θ (λ). FIG. 9B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 9C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 23 to Table 25.

<Example 4>
A coating solution IRA1 was prepared in the same manner as in Example 1. A transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) was coated on one main surface by a die coater, and was oven-treated at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 A heat treatment was carried out at 3 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.2 mm.

Next, an infrared reflection film irr1 was formed on the infrared absorption layer ira11 using a vacuum deposition apparatus. In the infrared reflecting film irr1, 16 layers of SiO ₂ and TiO ₂ were alternately laminated. An infrared reflective film was formed on one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) under the same conditions as the formation of the infrared reflective film irr1, and a laminate according to Reference Example 4 was produced. The transmittance spectrum of the laminate according to Reference Example 4 is shown in FIG. 10A. The laminate according to Reference Example 4 had the following characteristics (u1) to (u3).
(U1): When the incident angle of light is 0 °, the transmittance at a wavelength of 380 nm is 1.8%, the transmittance at a wavelength of 400 nm is 7.3%, and the average transmittance at a wavelength of 450 to 700 nm Is 94.8%, the minimum transmittance at a wavelength of 450 to 700 nm is 93.4%, the average transmittance at a wavelength of 700 to 800 nm is 94.0%, and the transmittance at a wavelength of 1100 nm is 4.4. 1%, IR cutoff wavelength was 902 nm, and UV cutoff wavelength was 410 nm.
(U2): When the incident angle of light is 30 °, the transmittance at a wavelength of 380 nm is 1.8%, the transmittance at a wavelength of 400 nm is 67.8%, and the average transmittance at a wavelength of 450 to 700 nm Is 95.0%, the minimum value of the transmittance at a wavelength of 450 to 700 nm is 93.8%, the average transmittance at a wavelength of 700 to 800 nm is 92.1%, and the transmittance at a wavelength of 1100 nm is 5. 3%, the IR cutoff wavelength was 863 nm, and the UV cutoff wavelength was 398 nm.
(U3): When the incident angle of light is 40 °, the transmittance at a wavelength of 380 nm is 4.0%, the transmittance at a wavelength of 400 nm is 90.2%, and the average transmittance at a wavelength of 450 to 700 nm Is 94.1%, the minimum transmittance at a wavelength of 450 to 700 nm is 92.9%, the average transmittance at a wavelength of 700 to 800 nm is 91.5%, and the transmittance at a wavelength of 1100 nm is 8. The IR cutoff wavelength was 837 nm, and the UV cutoff wavelength was 391 nm.

A deposited film (protective layer p2) of SiO _{2 having} a thickness of 500 nm was formed on the infrared absorption layer ira12. On the protective layer p2, the coating solution UVA1 used in Example 1 was applied by spin coating, and the coating film was heated and cured at 140 ° C. for 30 minutes to form an ultraviolet absorbing layer uva1. The thickness of the ultraviolet absorbing layer uva1 was 6 μm. An antireflection film ar2 was formed on the ultraviolet absorbing layer uva1 using a vacuum deposition apparatus. The antireflection film ar2 is a film in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar2 has seven layers and a total film thickness of about 0.4 μm. In this way, an optical filter according to Example 4 was obtained.

FIG. 10B and Table 26 show the transmittance spectrum of the optical filter according to Example 4. Further, the optical filter according to Example 4 had the characteristics shown in Table 27. In the same manner as in the first embodiment, the spectral transmittances T _θ (λ) and R (of the optical filter according to the fourth embodiment for the cases where the incident angles θ of light are 0 °, 30 °, and 40 °, respectively. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 11A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). FIG. 11B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 11C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 28 to Table 30.

<Example 5>
A coating solution IRA1 was prepared in the same manner as in Example 1. A transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) was coated on one main surface by a die coater, and was oven-treated at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 A heat treatment was carried out at 3 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.2 mm.

Next, in the same manner as in Example 4, an infrared reflection film irr1 was formed on the infrared absorption layer ira11 using a vacuum evaporation apparatus. In the infrared reflecting film irr1, 16 layers of SiO ₂ and TiO ₂ were alternately laminated.

A deposited film (protective layer p2) of SiO _{2 having} a thickness of 500 nm was formed on the infrared absorption layer ira12. On the protective layer p2, the coating solution UVIRA1 used in Example 2 was applied under the same conditions as in Example 2, and the coating film was heated at 140 ° C. for 30 minutes to be cured to form an infrared / ultraviolet absorbing layer uvira1. did. The thickness of the infrared / ultraviolet absorbing layer uvira1 was 7 μm. An antireflection film ar2 was formed on the infrared / ultraviolet absorption layer uvira1 using a vacuum deposition apparatus. The antireflection film ar2 is a film in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar2 has seven layers and a total film thickness of about 0.4 μm. In this way, an optical filter according to Example 5 was obtained.

The transmittance spectrum of the optical filter according to Example 5 is shown in FIG. The optical filter according to Example 5 had the characteristics shown in Table 32. In the same manner as in the first embodiment, the spectral transmittances T _θ (λ) and R (of the optical filter according to the fifth embodiment for the cases where the incident angles θ of light are 0 °, 30 °, and 40 °, respectively. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 13A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). FIG. 13B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 13C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 33 to Table 35.

<Example 6>
Coating liquid IRA1 and coating liquid IRA2 were prepared in the same manner as in Example 1. A transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) was coated on one main surface by a die coater, and was oven-treated at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 A heat treatment was carried out at 3 ° C. for 3 hours to cure the coating film and form an infrared absorption layer ira11. Similarly, coating liquid IRA1 was applied to the opposite main surface of the transparent glass substrate, and heat treatment was performed under the same conditions as above to cure the coating film, thereby forming infrared absorption layer ira12. The total thickness of the infrared absorption layer ira11 and the infrared absorption layer ira12 was 0.4 mm.

A deposited film (protective layer p1) of SiO _{2 having} a thickness of 500 nm was formed on the infrared absorption layer ira11 using a vacuum deposition apparatus. Similarly, a deposited SiO ₂ film (protective layer p2) having a thickness of 500 nm was formed on the infrared absorption layer ira12. The coating liquid IRA2 is applied to the surface of the protective layer p1 by a die coater, and is heated in an oven at 85 ° C. for 3 hours, then at 125 ° C. for 3 hours, then at 150 ° C. for 1 hour, and then at 170 ° C. for 3 hours. The coating film was cured to form an infrared absorption layer ira21. Also, the coating liquid IRA2 was applied to the surface of the protective layer p2 with a die coater, and the coating film was cured under the same heating conditions to form the infrared absorption layer ira22, whereby a semi-finished product δ was obtained. The transmittance spectrum of the semi-finished product δ at an incident angle of 0 ° C. is shown in FIG. 14A. The semi-finished product δ had the following characteristics (δ1) to (δ8).
(Δ1): The average transmittance at a wavelength of 700 to 1100 nm was 0.5% or less.
(Δ2): The average transmittance at a wavelength of 700 to 1000 nm was 0.5% or less.
(Δ3): The average transmittance at a wavelength of 1100 to 1200 nm was 0.5% or less.
(Δ4): The average transmittance at a wavelength of 450 to 600 nm was 82.2%.
(Δ5): The average transmittance at a wavelength of 500 to 600 nm was 82.7%.
(Δ6): The transmittance at a wavelength of 400 nm was 42.0%, and the transmittance at a wavelength of 450 nm was 76.7%.
(Δ7): The IR cutoff wavelength was 613 nm, the UV cutoff wavelength was 404 nm, and the full width at half maximum of the transmission region was 209 nm.
(Δ8): The wavelength with a spectral transmittance of 20% at a wavelength of 600 to 800 nm was 637 nm.

An antireflection film ar1 was formed on the infrared absorption layer ira21 using a vacuum deposition apparatus. Further, an antireflection film ar2 was formed on the infrared absorption layer ira22 using a vacuum vapor deposition apparatus. The antireflection film ar1 and the antireflection film ar2 have the same specifications and are films in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar1 and the antireflection film ar2 have seven layers. The layer and total film thickness was about 0.4 μm. Thus, an optical filter according to Example 6 was obtained.

The transmittance spectrum of the optical filter according to Example 6 is shown in FIG. 14B and Table 36. In addition, the optical filter according to Example 6 had the characteristics shown in Table 37. In the same manner as in Example 1, the spectral transmittances T _θ (λ) and R (of the optical filter according to Example 6 for the cases where the incident angles θ of light are 0 °, 30 °, and 40 °, respectively. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 15A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). FIG. 15B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 15C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 38 to Table 40.

<Comparative Example 1>
A transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) is used to form an infrared reflection film irr2 by laminating 24 layers of SiO ₂ and TiO ₂ alternately using a vacuum deposition apparatus on one main surface, and a semi-product ε Got. The transmittance spectrum of the semi-finished product ε is shown in FIG. 16A. The semi-finished product ε had the following characteristics (ε1) to (ε3).
(Ε1): When the incident angle of light is 0 °, the transmittance at a wavelength of 380 nm is 0.5% or less, the transmittance at a wavelength of 400 nm is 3.1%, and the average transmittance at a wavelength of 450 to 600 nm Is 94.1%, the minimum transmittance at a wavelength of 450 to 600 nm is 92.6%, the transmittance at a wavelength of 700 nm is 86.2%, and the transmittance at a wavelength of 715 nm is 30.8%. Yes, the average transmittance at a wavelength of 700 to 800 nm was 12.4%, the transmittance at a wavelength of 1100 nm was 0.5% or less, the IR cutoff wavelength was 710 nm, and the UV cutoff wavelength was 410 nm. .
(Ε2): When the incident angle of light is 30 °, the transmittance at a wavelength of 380 nm is 1.7%, the transmittance at a wavelength of 400 nm is 77.7%, and the average transmittance at a wavelength of 450 to 600 nm is 94.1%, the minimum value of the transmittance at a wavelength of 450 to 600 nm is 93.0%, the transmittance at a wavelength of 700 nm is 8.2%, the transmittance at a wavelength of 715 nm is 2.2%, The average transmittance at 700 to 800 nm was 1.1%, the transmittance at a wavelength of 1100 nm was 1.2%, the IR cutoff wavelength was 680 nm, and the UV cutoff wavelength was 397 nm.
(Ε3): When the incident angle of light is 40 °, the transmittance at a wavelength of 380 nm is 13.1%, the transmittance at a wavelength of 400 nm is 90.5%, and the average transmittance at a wavelength of 450 to 600 nm is 92.1%, the minimum transmittance at a wavelength of 450 to 600 nm is 87.6%, the transmittance at a wavelength of 700 nm is 2.0%, and the transmittance at a wavelength of 715 nm is 0.8%. The average transmittance at a wavelength of 700 to 800 nm was 0.5% or less, the transmittance at a wavelength of 1100 nm was 5.4%, the IR cutoff wavelength was 661 nm, and the UV cutoff length was 386 nm.

A coating solution IRA3 containing an infrared absorbing dye was prepared as follows. The infrared absorbing dye was a combination of a cyanine organic dye soluble in MEK and a squarylium organic dye. An infrared absorbing dye was added to MEK as a solvent, PVB as a matrix material was further added, and then stirred for 2 hours to obtain a coating liquid IRA3. The content of the matrix material in the solid content of the coating liquid IRA3 was 99% by mass. After the coating liquid IRA3 was applied to the other main surface of the transparent glass substrate of the semi-finished product ε by spin coating, the coating film was heated and cured at 140 ° C. for 30 minutes to form an infrared absorption layer ira3. Separately, an infrared absorption layer is formed on one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) under the same conditions as the formation conditions of the infrared absorption layer ira3 to obtain a laminate according to Reference Example 5. It was. FIG. 16B shows the transmittance spectrum of the laminate according to Reference Example 5 at an incident angle of 0 °. The laminate according to Reference Example 5 had the following characteristics (v1) to (v4).
(V1): The transmittance at a wavelength of 700 nm was 2.0%, the transmittance at a wavelength of 715 nm was 2.6%, and the average transmittance at a wavelength of 700 to 800 nm was 15.9%.
(V2): The transmittance at a wavelength of 1100 nm was 91.1%.
(V3): The transmittance at a wavelength of 400 nm was 78.2%, the transmittance at 450 nm was 83.8%, and the average transmittance at a wavelength of 500 to 600 nm was 86.9%.
(V4): The IR cut-off wavelength at a wavelength of 600 nm to 700 nm is 637 nm, the IR cut-off wavelength at a wavelength of 700 nm to 800 nm is 800 nm, and the difference between these IR cut-off wavelengths is 163 nm, at a wavelength of 600 to 800 nm The maximum absorption wavelength was 706 nm.

  An antireflection film ar1 was formed on the infrared absorption layer ira3 in the same manner as in Example 1 using a vacuum vapor deposition apparatus, and an optical filter according to Comparative Example 1 was obtained.

The transmittance spectrum of the optical filter according to Comparative Example 1 is shown in FIG. Further, the optical filter according to Comparative Example 1 had the characteristics shown in Table 42. In the same manner as in Example 1, the spectral transmittances T _θ (λ) and R (of the optical filter according to Comparative Example 1 are respectively obtained when the light incident angles θ are 0 °, 30 °, and 40 °. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 17A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). FIG. 17B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 17C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 43 to Table 45.

<Comparative example 2>
An infrared-absorbing glass substrate having the transmittance spectrum shown in FIG. 18A at an incident angle of 0 ° was prepared. This infrared absorbing glass substrate had the following characteristics (g1) to (g5).
(G1): The average transmittance at a wavelength of 700 to 1000 nm was 16.8%.
(G2): The average transmittance at a wavelength of 1100 to 1200 nm was 38.5%.
(G3): The average transmittance at a wavelength of 450 to 600 nm was 87.8%.
(G4): The transmittance at a wavelength of 400 nm was 88.5%.
(G5): IR cut-off wavelength was 653 nm. The wavelength corresponding to a transmittance of 20% at a wavelength of 600 to 800 nm was 738 nm.

An infrared reflecting film irr3 was formed by alternately stacking 20 layers of SiO ₂ and TiO ₂ on one main surface of an infrared-absorbing glass substrate having a thickness of 210 μm using a vacuum vapor deposition apparatus, to obtain a semi-finished product ζ. An infrared reflective film was formed on one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) under the same conditions as those for forming the infrared reflective film irr3, and a laminate according to Reference Example 6 was obtained. The transmittance spectrum of the laminate according to Reference Example 6 is shown in FIG. 18B. The laminate according to Reference Example 6 had the following characteristics (w1) to (w3).
(W1): When the incident angle of light is 0 °, the transmittance at a wavelength of 380 nm is 0.5% or less, the transmittance at a wavelength of 400 nm is 0.5% or less, and the average transmittance at a wavelength of 450 to 600 nm The transmittance is 95.2%, the minimum transmittance at a wavelength of 450 to 600 nm is 93.7%, the average transmittance at a wavelength of 700 to 800 nm is 4.7%, and the transmittance at a wavelength of 1100 nm is 0. The IR cutoff wavelength was 702 nm, and the UV cutoff wavelength was 411 nm.
(W2): When the incident angle of light is 30 °, the transmittance at a wavelength of 380 nm is 1.7%, the transmittance at a wavelength of 400 nm is 77.7%, and the average transmittance at a wavelength of 450 to 600 nm is 94.1%, the minimum transmittance at a wavelength of 450 to 600 nm is 93.0%, the average transmittance at a wavelength of 700 to 800 nm is 1.1%, and the transmittance at a wavelength of 1100 nm is 1.2. %, The IR cutoff wavelength was 680 nm, and the UV cutoff wavelength was 397 nm.
(W3): When the incident angle of light is 40 °, the transmittance at a wavelength of 380 nm is 13.1%, the transmittance at a wavelength of 400 nm is 90.5%, and the average transmittance at a wavelength of 450 to 600 nm is 92.1%, the minimum transmittance at a wavelength of 450 to 600 nm is 87.6%, the average transmittance at a wavelength of 700 to 800 nm is 0.5% or less, and the transmittance at a wavelength of 1100 nm is 5. The IR cutoff wavelength was 661 nm and the UV cutoff wavelength was 386 nm.

A coating solution UVIRA2 containing an infrared absorbing dye and an ultraviolet absorbing dye was prepared as follows. The ultraviolet absorbing dye was a dye made of a benzophenone ultraviolet absorbing substance that hardly absorbs light in the visible light region. The infrared absorbing dye was a combination of a cyanine organic dye and a squarylium organic dye. The infrared absorbing dye and the ultraviolet absorbing dye were soluble in MEK. An infrared absorbing dye and an ultraviolet absorbing dye were added to MEK as a solvent, PVB as a matrix material was further added, and then stirred for 2 hours to obtain a coating solution UVIRA2. The PVB content in the solid content of the coating liquid UVIRA2 was 60% by mass. The coating liquid UVIRA2 was applied to the other main surface of the semi-finished product ζ, and the coating film was heated and cured to form an infrared / ultraviolet absorbing layer uvira2. The thickness of the infrared / ultraviolet absorbing layer uvira2 was 7 μm. An infrared / ultraviolet absorption layer is formed on one main surface of a transparent glass substrate (manufactured by SCHOTT, product name: D263T eco) using the coating liquid UVIRA2 under the same conditions as those for forming the infrared / ultraviolet absorption layer uvira2. A laminate according to Reference Example 7 was obtained. FIG. 18C shows the transmittance spectrum of the laminate according to Reference Example 7 at an incident angle of 0 °. The laminate according to Reference Example 7 had the following characteristics (p1) to (p5).
(P1): The transmittance at a wavelength of 700 nm was 4.9%, the transmittance at a wavelength of 715 nm was 8.4%, and the average transmittance at a wavelength of 700 to 800 nm was 63.9%.
(P2): The transmittance at a wavelength of 1100 nm was 92.3%.
(P3): The transmittance at a wavelength of 400 nm was 12.6%, the transmittance at 450 nm was 84.4%, and the average transmittance at a wavelength of 500 to 600 nm was 88.7%.
(P4): The IR cutoff wavelength at wavelengths of 600 nm to 700 nm was 664 nm, the IR cutoff wavelength at wavelengths of 700 nm to 800 nm was 731 nm, and the difference between them was 67 nm. The wavelength (maximum absorption wavelength) showing the lowest transmittance at wavelengths of 600 nm to 800 nm was 705 nm.
(P5): The UV cutoff wavelength at wavelengths of 350 nm to 450 nm was 411 nm.

An antireflection film ar1 was formed on the infrared / ultraviolet absorbing layer uvira2 in the same manner as in Example 1 by using a vacuum deposition apparatus. The antireflection film ar1 is a film in which SiO ₂ and TiO ₂ are alternately laminated. The antireflection film ar1 has seven layers and a total film thickness of about 0.4 μm. In this way, an optical filter according to Comparative Example 2 was obtained.

The transmittance spectrum of the optical filter according to Comparative Example 2 is shown in FIG. In addition, the optical filter according to Comparative Example 2 had the characteristics shown in Table 47. In the same manner as in Example 1, the spectral transmittances T _θ (λ) of the optical filter according to Comparative Example 2 and R (R) for the cases where the incident angles θ of light are 0 °, 30 °, and 40 °, respectively. Normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) based on each function of λ), G (λ), and B (λ) were obtained. FIG. 19A shows a graph of normalized color matching functions r (λ) and CR _θ (λ). FIG. 19B shows a graph of the normalized color matching functions g (λ) and CG _θ (λ). FIG. 19C shows a graph of the normalized color matching functions b (λ) and CB _θ (λ). Based on the normalized spectral sensitivity functions CR _θ (λ), CG _θ (λ), and CB _θ (λ) and the normalized color matching functions r (λ), g (λ), and b (λ), (1) to (9), IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB and IAE _θ ^rR , IAE _θ for the incident angles θ ° of 0 °, 30 °, and 40 °, respectively. ^gG and IAE _θ ^bB and ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB were determined. The results are shown in Table 48 to Table 50.

  In the optical filters according to Examples 1 to 6, the above conditions (i) to (vii) were satisfied. In the optical filter which concerns on Examples 1-6, the transmittance | permeability in a 700 nm or more wavelength range is low enough, and it was shown that the optical filter which concerns on Examples 1-6 can shield near infrared rays favorably. The optical filter according to Example 2 showed lower transmittance in the wavelength range of 700 nm or more than the optical filter according to Example 1. In the optical filter according to Example 2, the transmittance in the visible light region was about 2 points lower than that of the optical filter according to Example 1 due to the inclusion of the organic infrared absorbing dye. However, there is no problem in practical use. Since the optical filter according to Example 3 has only the infrared absorption layer ira11 and the infrared absorption layer ira12 as the infrared absorption layer, as compared with the optical filter according to Examples 1 and 2, in the wavelength range of 1100 nm or more, 700 Higher transmittance was shown compared to the wavelength range of ˜1100 nm. However, since the sensitivity of an image sensor such as a CMOS sensor with respect to light having a wavelength of 1100 nm or more is low, the optical filter according to Example 3 is considered to have appropriate characteristics for the image pickup apparatus. In the optical filter according to Example 6, the transmittance near the wavelength of 400 nm was higher than that of the optical filters of the other examples, but was 45% or less.

  In the optical filters according to Examples 1 to 6, the conditions shown in Tables (II) to (VIII) were satisfied. In the optical filters according to Examples 1 to 6, the spectral transmittance with respect to the incident angles of 0 °, 30 °, and 40 ° was hardly changed. For this reason, when the optical filter according to Examples 1 to 6 is incorporated in an imaging apparatus such as a camera, even if the incident angle of light on the optical filter changes, the change in the sensitivity curve based on the output from the imaging apparatus is slight. It was suggested that In the infrared reflective film of the optical filter according to Examples 4 and 5, the boundary between the wavelength band that transmits light with an incident angle of 40 ° and the wavelength band that reflects light with an incident angle of 40 ° is approximately 850 nm. It was set. For this reason, the spectral transmittances of the optical filters according to Examples 4 and 5 hardly changed at incident angles of 0 °, 30 °, and 40 °. In the optical filters according to Examples 4 and 5, the greater the incident angle of light, the higher the transmittance near the wavelength of 400 nm. Therefore, the difference between the IE at the incident angle of 0 ° and the IE at the incident angle of 30 ° and the range thereof. There was something that was slightly larger. However, it is considered that there is no practical problem. In the optical filters according to Examples 1 to 6, the local transmittance change (ripple) is a part where the curve of the normalized spectral sensitivity function has a relatively large difference from the curve of the normalized color matching function at wavelengths of 450 to 600 nm. ) Did not occur. As a result, IE, IAE, and ISE at an incident angle of 0 ° are subtracted from IE, IAE, and ISE at an incident angle of 30 °, respectively, and IE, IAE, and ISE at an incident angle of 0 ° are 40 ° Substantial changes in IE, IAE, and ISE subtracted from the incident angle, and IE, IAE, and ISE subtracted from the incident angle of 30 ° minus IE, IAE, and ISE, respectively. Did not occur. For this reason, when the optical filter according to the first to sixth embodiments is incorporated in an imaging apparatus, even if a light beam is incident on the optical filter in an incident angle range of 0 ° to 40 °, It is considered that there is no color unevenness inside.

In the optical filter according to Comparative Example 1, the boundary between the visible light region adjacent to the near-infrared region and the wavelength band that transmits light in the near-infrared region and the wavelength band that blocks light are determined by the infrared absorption layer ira3. It has been. However, since the absorption band of the infrared absorption layer ira3 is narrow, in the transmittance spectrum of the optical filter according to Comparative Example 1, the reflection band of the infrared reflection film shifts to the short wavelength side as the incident angle of light increases. I was affected. Further, the optical filter according to Comparative Example 1 has insufficient light absorption capability in the ultraviolet region, and the optical filter according to Comparative Example 1 substantially shielded the light in the ultraviolet region only by the infrared reflection film irr2. . For this reason, the optical filter according to Comparative Example 1 was strongly affected by the shift of the reflection band to the short wavelength side depending on the incident angle of light in the ultraviolet region. In the optical filter according to Comparative Example 1, as the incident angle of light increases, CR _θ (λ) decreases near the wavelength of 650 nm and approaches the normalized color matching function r (λ). IE _θ ^rR corresponding to the integral value of the difference between the function r (λ) and the normalized spectral sensitivity CR _θ (λ) increased. On the other hand, CB _θ (λ) does not monotonously increase or decrease as the incident angle of light increases, but fluctuates in the vicinity of a wavelength of 410 nm. This is not only because the transmission band of the infrared reflection film irr2 is shifted by the incident angle of light, but also in the transmittance of the optical filter according to Comparative Example 1 at an incident angle of 40 °, a ripple is generated at a wavelength of 400 nm to 430 nm, and is close This is probably because the transmittance at a wavelength of 440 nm was drastically decreased by 15 points or more. Therefore, IE, IAE, and ISE at an incident angle of 0 ° are subtracted from IE, IAE, and ISE at an incident angle of 30 °, respectively, and IE, IAE, and ISE at an incident angle of 0 ° are 40 ° There is a significant change in the difference in IE, IAE, and ISE at the incident angle, respectively, and IE, IAE, and ISE at the incident angle of 30 ° minus the IE, IAE, and ISE, respectively, at the incident angle of 40 °. It was happening. In addition, the behavior of the change in CR _θ (λ) with respect to the normalized color matching function r (λ) with the change in the incident angle and the CB _θ (λ) with respect to the normalized color matching function b (λ) with the change in the incident angle. The behavior of the change was different, and CR _θ (λ) and CB _θ (λ) fluctuated greatly in a narrow range between the incident angle of 30 ° and the incident angle of 40 °. For this reason, when the optical filter according to Comparative Example 1 is incorporated in the imaging apparatus, there is a concern that strong color unevenness may occur inside the image.

  In the optical filter according to Comparative Example 2, in the region adjacent to the near-infrared region of the visible light region, the near-infrared region, and the ultraviolet region, the boundary between the wavelength band that transmits light and the wavelength band that blocks light is infrared / ultraviolet absorption. It was determined by the layer uvira2. However, since the absorption band of the infrared / ultraviolet absorption layer uvira2 in the near-infrared region is narrow, in the optical filter according to Comparative Example 2, the reflection band by the infrared reflection film irr3 cannot be set sufficiently long. For this reason, in the optical filter according to Comparative Example 2, the influence of the reflection band shifting to the short wavelength side as the incident angle of light increases cannot be avoided. In addition, a local variation in the transmittance of the optical filter according to Comparative Example 2 at an incident angle of 40 ° was observed in the visible light region. For this reason, in the optical filter according to Comparative Example 2, the change in IE and IAE accompanying the change in the incident angle of light is large, and when the optical filter according to Comparative Example 2 is incorporated in the imaging apparatus, strong color unevenness is generated inside the image. There is a concern that this will occur.

DESCRIPTION OF SYMBOLS 1a-1f Optical filter 2 Lens system 3 Color filter 4 Image pick-up element 10 Light absorption layer 20 Transparent dielectric substrate 30 Antireflection film 40 Reflective film 100 Imaging device (camera module)

Claims (11)

An optical filter,
Comprising a light absorbing layer containing a light absorber that absorbs at least part of light in the near infrared region,
When light having a wavelength of 300 nm to 1200 nm is incident on the optical filter at incident angles of 0 °, 30 °, and 40 °, the following conditions are satisfied:
(I) Spectral transmittance at a wavelength of 700 nm is 3% or less.
(Ii) Spectral transmittance at a wavelength of 715 nm is 1% or less.
(Iii) Spectral transmittance at a wavelength of 1100 nm is 7.5% or less.
(Iv) The average transmittance at a wavelength of 700 nm to 800 nm is 1% or less.
(V) The average transmittance at a wavelength of 500 nm to 600 nm is 85% or more.
(Vi) Spectral transmittance at a wavelength of 400 nm is 45% or less.
(Vii) The spectral transmittance at a wavelength of 450 nm is 80% or more.
The spectral transmittance of the optical filter at the wavelength λ when the incident angle is θ ° is expressed as T _θ (λ),
The product of T _θ (λ) and R (λ), G (λ), and B (λ), which is a function of the wavelength λ defined by Table (I) in the wavelength range of 400 nm to 700 nm. Functions obtained by normalizing the respective functions determined with respect to the incident angle θ ° so that the maximum value is 1 are _represented as CR _θ (λ), CG _θ (λ), and CB _θ (λ),
Stiles & Burch (1959) The function of wavelength λ obtained by normalizing the color matching functions defined in 10-deg, RCB CMFs so that the maximum value is 1, respectively, is r (λ), g (λ), and b (λ),
When the wavelength λ which is a variable of CR _θ (λ), CG _θ (λ), and CB _θ (λ) is expressed as λ (n) = (Δλ × n + 400) nm as a function of n which is an integer of 0 or more. (Where Δλ = 5),
Nine differences in IE _θ ^rR , IE _θ ^gG , and IE _θ ^bB defined for each of incident angles θ ° of 0 °, 30 °, and 40 ° by the following equations (1)-(3) A range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of IE _θ ^rR , IE _θ ^gG , and IE _θ ^{bB for} the same two incident angles θ ° satisfies the condition shown in Table (II).
Optical filter.

0 °, 30 °, and IE _theta ^rR defined for 40 ° each incident angle theta ° of, IE _theta ^gG, and IE _theta IE for nine difference and the same two incident angle theta ° in ^bB _theta The optical filter according to claim 1, wherein a range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of ^rR , IE _θ ^gG , and IE _θ ^bB satisfies a condition shown in Table (III).

0 °, 30 °, and IE _theta ^rR defined for 40 ° each incident angle theta ° of, IE _theta ^gG, and IE _theta IE for nine difference and the same two incident angle theta ° in ^bB _theta The optical filter according to claim 1, wherein a range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of ^rR , IE _θ ^gG , and IE _θ ^bB satisfies a condition shown in Table (IV).

Nine differences in IAE _θ ^rR , IAE _θ ^gG , and IAE _θ ^bB defined for each of incident angles θ ° of 0 °, 30 °, and 40 ° by the following equations (4)-(6) and The range which is a difference obtained by subtracting the minimum value from the maximum value of the three differences of IAE _θ ^rR , IAE _θ ^gG and IAE _θ ^{bB for} the same two incident angles θ ° satisfies the condition shown in Table (V). Item 4. The optical filter according to any one of Items 1 to 3.

0 °, 30 °, and IAE _theta ^rR defined for 40 ° each incident angle theta ° of, IAE _theta ^gG, and IAE _theta IAE _theta for nine difference and the same two incident angle theta ° in ^bB The optical filter according to claim 4, wherein a range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of ^rR , IAE _θ ^gG , and IAE _θ ^bB satisfies a condition shown in Table (VI).

Nine differences in ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^bB defined for each of incident angles θ ° of 0 °, 30 °, and 40 ° according to equations (7)-(9) below: A range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of ISE _θ ^rR , ISE _θ ^gG , and ISE _θ ^{bB for} the same two incident angles θ ° satisfies the conditions shown in Table (VII). Item 6. The optical filter according to any one of Items 1 to 5.

0 °, 30 °, and ISE _theta ^rR defined for 40 ° each incident angle theta ° of, ISE _theta ^gG, and ISE _theta for nine difference and the same two incident angle theta ° in ISE _theta ^bB The optical filter according to claim 6, wherein a range that is a difference obtained by subtracting a minimum value from a maximum value of three differences of ^rR , ISE _θ ^gG , and ISE _θ ^bB satisfies the condition shown in Table (VIII).

  The optical filter according to claim 1, wherein the light absorber is formed of phosphonic acid and copper ions.   The optical filter according to claim 8, wherein the phosphonic acid includes a first phosphonic acid having an aryl group.   The optical filter according to claim 9, wherein the phosphonic acid further includes a second phosphonic acid having an alkyl group. A lens system,
An image sensor that receives light that has passed through the lens system;
A color filter disposed in front of the image sensor and having three color filters of R (red), G (green), and B (blue);
The optical filter according to any one of claims 1 to 10 disposed in front of the color filter.
Imaging device.

Images