JP2019200399A - Optical filter and imaging device - Google Patents

Abstract

To provide an optical filter with which it is possible to realize the downsizing (slimming down) of an imaging device and maintain shock resistance and optical functionality, and with which a reflection color is adjusted.SOLUTION: Provided is an optical filter 10 comprising: a transparent substrate 11 having a first principal surface and a second principal surface facing the first principal surface and transmitting visible range light; an absorption layer 12 provided on the second principal surface and having near-infrared absorption ability for absorbing at least near-infrared light; and a reflection layer 13 laminated on the absorption layer, for transmitting visible range light and reflecting ultraviolet and near-infrared range light. The thickness of the transparent substrate is 0.2-0.5 mm, and the surface strength of at least one of the first and second principal surfaces is 170 N or greater.SELECTED DRAWING: Figure 1A

Description

  The present invention relates to an optical filter that transmits light in the visible region and blocks light in the near-ultraviolet region and the near-infrared region, an imaging device including the optical filter, and a portable device including the imaging device.

  In an imaging device using a solid-state imaging device such as a CCD or CMOS image sensor mounted on a digital still camera or the like, in order to reproduce a color tone well according to human visual sensitivity and obtain a clear image, a visible region An optical filter that transmits light in the near-ultraviolet region and the near-infrared region is used.

  FIG. 15 is a cross-sectional view (partially enlarged view) schematically showing a portion where an imaging device 210 is mounted in a portable device 200 which is a conventional embodiment. Specifically, an imaging device 210, a cover glass 26, and a casing 27 of a portable device are shown. Here, the imaging device 210 is provided inside the solid-state imaging device 21, the optical filter 22, the imaging lens 23, the housing 24 of the imaging device that houses them, and the housing 24 of the imaging device. The solid-state image sensor 21 and the imaging lens 23 are arranged along the optical axis X. A cover glass 26 and a casing 27 of a portable device that fixes the cover glass 26 are arranged in a direction in which light is incident on the imaging device 210.

  Here, the solid-state imaging device 21 is an electronic component that converts light that has passed through the imaging lens 23 into an electrical signal. Specifically, a CCD, CMOS, or the like is used.

  The cover glass 26 prevents the imaging lens from being damaged due to a mechanical load such as dropping or wear. The light that has passed through the cover glass 26 and entered the imaging device 210 passes through the imaging lens 23 and the optical filter 22 and is received by the solid-state imaging device 21, and is converted into an electrical signal by the solid-state imaging device 21. Output as an image signal.

  In addition, in the imaging device 210 illustrated in FIG. 15, a configuration including one lens is schematically illustrated as the imaging lens 23, but a plurality of lenses may be used to achieve high resolution with a wide viewing angle (low F number). It is also generally performed to combine the two.

  Examples of such portable devices include mobile phones, smart phones, and mobile personal computers. In recent years, imaging devices mounted on such portable devices have been further reduced in size and functionality, and the optical filter has a thin thickness. There is also a need to make it.

  As a conventional optical filter that blocks ultraviolet light and near infrared light, an optical filter having a near infrared absorption layer in which a near infrared absorption dye is dispersed in a transparent resin and a reflective selective wavelength blocking layer composed of a dielectric multilayer film is used. Example of filter configuration (for example, refer to Patent Document 1), configuration of optical filter including transparent base material made of absorption glass, absorption layer made of transparent resin containing ultraviolet absorber and near infrared absorber, and reflection layer An example is known (see, for example, Patent Document 2).

  As a configuration example of such a conventional optical filter, FIG. 16A schematically shows an example of a configuration cross-sectional view of a conventional optical filter 22A. The optical filter 22A has a reflection wavelength band in the near-infrared wavelength region and the ultraviolet wavelength region made of a dielectric multilayer film on the surface on the imaging lens 23 side of the fluorophosphate-type absorption glass 12c to which CuO is added. A reflection layer 13 is formed, and an absorption layer 12b made of a transparent resin containing an ultraviolet absorber and a near infrared absorber and an antireflection film 14 are formed on the surface on the solid-state imaging device 21 side.

  In the optical filter 22 </ b> A, the light that has passed through the cover glass 26, the imaging lens 23, and the optical filter 22 and reaches the solid-state imaging device 21 is reflected by the light receiving surface of the solid-state imaging device 21. In order to prevent stray light from being reflected again and reaching the solid-state imaging device 21, the reflection layer 13 having a high reflectance in the near infrared and ultraviolet wavelength regions is placed on the imaging lens 23 side of the absorption glass 12c, and the near infrared and ultraviolet wavelengths. The absorption layer 12b that absorbs the region is disposed on the solid-state imaging device 21 side. Further, in order to reduce the reflected light generated at the interface between the absorption layer 12b and air and improve the transmittance in the visible wavelength region, the antireflection film 14 is formed on the surface of the absorption layer 12b.

  Further, there is known a cover glass on which an antireflection film that is hard to be scratched even when rubbed and has a high scratch resistance (see, for example, Patent Document 3). Such a cover glass is preferably used as the cover glass 26, and is not easily broken or deformed due to a mechanical load such as dropping or collision of the portable device. As the cover glass 26, it is preferable to use chemically tempered glass (for example, see Patent Document 4). However, glass that is not chemically strengthened such as quartz, crystal, sapphire, or resin material such as polycarbonate may be used. Good. Sapphire is particularly preferable from the viewpoint of the strength or hardness of the substrate. On the light incident surface of the cover glass 26, it is preferable to form an anti-reflective film having high scratch resistance, a coating having a fingerprint-proofing effect that prevents fingerprints from sticking or being noticeable. Further, an antireflection film in the visible wavelength region is provided on the light emitting surface as necessary.

  The thickness t of the cover glass 26 used here is preferably as thick as possible in order to maintain impact resistance, but is preferably 0.5 mm or less from the viewpoint of reducing the thickness of the portable device. On the other hand, the impact resistance of the cover glass 26 is compared with the surface strength F (BOR strength: unit N) obtained by a glass ball-on-ring bending test, and the surface strength F is proportional to the square of the thickness t. The thicker the thickness t, the higher the impact resistance. The surface strength F of the cover glass 26 is preferably 170 N or more. For example, in the cover glass 26 using sapphire having a thickness t = 0.3 mm, a surface strength of about 210 N has been confirmed by a ball-on-ring bending test.

International Publication No. 2012-169447 International Publication No. 2016-114363 International Publication No. 2013-183457 International Publication No. 2015-008766

  By the way, the thinning of the optical filter necessary for further downsizing of the imaging device is approaching the limit in terms of securing impact resistance and maintaining optical characteristics. Therefore, in order to reduce the thickness of the entire portable device, for example, it is possible to omit the cover glass and use the conventional optical filter 22A shown in FIG. 16A instead of the cover glass. However, in this case, the surface strength of the absorptive glass 12c that secures the strength as an optical filter is significantly inferior to the surface strength of the conventional cover glass 26, so that the impact resistance cannot be sufficiently secured. Can be considered.

  Further, in this case, incident light in the near-infrared wavelength band of 700 to 1100 nm is reflected by the reflective layer 13 formed on the surface of the absorption glass 12c on the light incident surface side, and a reflection color corresponding to the spectral reflectance is obtained. However, with respect to incident light with an incident angle of 0 to 30 °, the reflectivity of the reflective layer 14 in the visible wavelength range of 420 to 670 nm, which has high visibility, is low, and there is no problem. In the conventional imaging apparatus 210 shown in FIG. 15, the incident angle of light incident on the optical filter 22 is defined by the F number of the imaging lens 23, and is not a clear reflected color because it is about 0 to 30 degrees. However, when the optical filter 22A is used instead of the cover glass, the near-infrared reflection wavelength band shifts to the short wavelength side as the incident angle increases, and the reflectance in the red wavelength region of 650 nm or more is obtained at an incident angle of 45 ° or more. It becomes as large as 50% or more and is visually recognized as a clear reflected color. As a result, the reflected color of the entire cover glass is limited to the red region, and the appearance may not match the reflected color of the casing of the portable device.

  Further, as an improvement in strength when using FIG. 16A as a cover glass, it may be possible to integrate the optical filter 22A with a conventional cover glass. As an example of such a configuration, FIG. A cross-sectional view of the optical filter 22B integrated with is schematically shown. The optical filter 22B has a configuration in which the cover glass 26 and the optical filter 22A are provided as they are on the imaging device side of the cover glass 26. At this time, the adhesive layer 16 for adhering the cover glass 26 and the optical filter 22A is provided.

  Although the strength is improved by adopting a configuration like this optical filter 22B, the characteristics relating to the reflected light are not changed, and the reflected color of the entire cover glass is also limited to the red range, and does not match the reflected color of the portable device. The point which may become an external appearance is the same as that of the said optical filter 22A.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical filter that realizes downsizing (thinning) of an imaging device mounted on a portable device and that can maintain impact resistance and optical function. It is another object of the present invention to provide an optical filter in which the reflection color is adjusted, and the appearance of the cover glass is adjusted to a design that does not feel uncomfortable with the casing of the portable device. Furthermore, it aims at provision of the imaging device provided with this optical filter, and the portable apparatus provided with this imaging device further.

  As a result of intensive studies on the above problems, the present inventors have secured the impact resistance by integrating the function of the optical filter with the cover glass that is used in the imaging device portion of the portable device and has secured the impact resistance. However, the present inventors have found an optical filter that can secure an optical function and eliminate the optical filter in the imaging apparatus, and has completed the present invention.

  That is, the optical filter of the present invention has a first main surface and a second main surface opposite to the first main surface, the transparent substrate that transmits light in the visible range, and the second main surface. An absorption layer having a near-infrared absorption capability that absorbs at least near-infrared light, and is laminated on the absorption layer, transmits visible light, and transmits ultraviolet and near-infrared light. An optical filter having a reflective layer, the transparent substrate having a thickness of 0.2 to 0.5 mm, and at least one main surface of the first main surface and the second main surface The surface strength of the material is 170N or more.

  According to the optical filter of the present invention, it is possible to achieve a reduction in size (thinning) of the imaging device by maintaining good impact resistance and optical function and using it as a component of the imaging device mounted on a portable device or the like. it can. In addition, by having a configuration having predetermined characteristics, it exhibits a stable filter function against light irradiation in a wide wavelength band including ultraviolet rays from the outside, and is suitably used as a cover glass of an imaging device mounted on a portable device. be able to. In this optical filter, the color temperature of the reflected light from the cover glass provided with the function of the optical filter is higher than that of white light (6500 K), and the appearance color close to bluish white can be obtained.

  Since the imaging apparatus and portable device of the present invention have the optical filter of the present invention, the imaging apparatus and the portable device can be reduced in size (thinned) and can stably capture images with a stable filter function.

It is sectional drawing of the optical filter which shows the structural example of 1st Embodiment. It is sectional drawing of the optical filter which shows the structural example of 2nd Embodiment. It is sectional drawing of the optical filter which shows the structural example of 3rd Embodiment. It is sectional drawing of the optical filter which shows the structural example of 4th Embodiment. It is sectional drawing which shows typically the structural example of the portable apparatus by which the optical filter and imaging device of 1st Embodiment are mounted. It is a graph which shows the example of the spectral reflectance of the antireflection film of the 1st main surface of the transparent substrate used for the optical filter of this embodiment. It is a graph which shows the other example of the spectral reflectance of the antireflection film of the 1st main surface of the transparent substrate used for the optical filter of this embodiment. It is a graph which shows the example of the spectral reflectance of the antireflection film of the 2nd principal surface of the transparent substrate used for the optical filter of this embodiment. It is a graph which shows the other example of the spectral reflectance of the antireflection film of the 2nd main surface of the transparent substrate used for the optical filter of this embodiment. It is a graph which shows the example of the spectral transmittance of the near-infrared absorption layer containing the near-infrared absorption pigment | dye used for the optical filter of this embodiment. It is a graph which shows the example of the spectral transmittance of the near ultraviolet absorption layer containing the near ultraviolet absorption pigment | dye used for the optical filter of this embodiment. It is a graph which shows the example of the spectral transmittance of the absorption layer containing the near-infrared absorption pigment | dye used for the optical filter of this embodiment, and a near-ultraviolet absorption pigment | dye. It is a graph which shows the example of the spectral transmittance of the absorption layer which contained the coloring material used for the optical filter of this embodiment in high concentration. It is a graph which shows the example of the spectral reflectance in which the absorption layer which contained the coloring material used for the optical filter of this embodiment in low concentration was formed on the reflective layer of 10% reflectance. It is a graph which shows the example of the spectral transmittance of the reflection layer which permeate | transmits the visible region used for the optical filter of this embodiment, and shields an ultraviolet-ray zone and a near-infrared zone by reflection. 6 is a graph showing an example of spectral transmittance of the optical filter of Example 1. 6 is a graph showing an example of spectral reflectance of the optical filter of Example 1. 6 is a graph showing an example of spectral transmittance of the optical filter of Example 2. 6 is a graph showing an example of spectral reflectance of the optical filter of Example 2. 10 is a graph showing an example of spectral transmittance of the optical filter of Example 3. 10 is a graph showing an example of spectral reflectance of the optical filter of Example 3. 10 is a graph showing an example of spectral reflectance of the optical filter of Example 4. It is a graph which shows the example of the spectral reflectance of the optical filter of a comparative example. It is sectional drawing which shows typically the example of a part of portable device with which the imaging device incorporating the optical filter of a prior art example, and a cover glass were mounted. It is sectional drawing which shows the example of the optical filter of a prior art example typically. It is sectional drawing which shows typically the example which integrated the optical filter of the prior art example with the conventional cover glass.

  Hereinafter, the present invention will be described with reference to embodiments. In this specification, a refractive index without wavelength description means a refractive index with respect to light having a wavelength of 589 nm at 20 ° C. unless otherwise specified.

[Optical filter]
As described above, the optical filter of the present invention has a first main surface and a second main surface opposite to the first main surface, and a transparent substrate that transmits light in the visible range; An absorption layer that is provided on the main surface and has a near-infrared absorption capability that absorbs at least near-infrared light, and is laminated on the absorption layer, transmits visible light, and transmits light in the ultraviolet and near-infrared regions. An optical filter having a reflective layer for reflecting the transparent substrate and satisfying predetermined characteristics with respect to the transparent substrate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
As shown in FIG. 1A, the optical filter according to the first embodiment of the present invention is an optical filter 10 having a transparent substrate 11, an absorption layer 12, a reflection layer 13, and an antireflection film 14. . Hereinafter, each of these components will be described in detail.

(Transparent substrate)
The transparent substrate 11 used in the first embodiment is made of a material that transmits light in the visible range of at least 420 to 660 nm, and includes a first main surface and a second main surface facing the first main surface. A transparent substrate.

  The transparent substrate 11 has a high impact resistance that is unlikely to cause breakage such as cracking due to an impact caused by a drop or collision of a portable device, and is hardly subject to surface scratches or alteration due to wear or the like, and has a visible range of at least 420 to 660 nm. It is preferable to use a material that transmits the light, and a cover glass that has been conventionally used for an imaging device portion of a portable device can be used.

  The transparent substrate 11 may be any material having translucency, and examples thereof include resin materials such as general glass, glass ceramics, quartz, crystal, sapphire, and polycarbonate. Among these materials, sapphire is preferable from the viewpoint of the strength or hardness of the substrate. The glass is preferably tempered glass, particularly chemically tempered glass.

  Specific examples of the chemically tempered glass include Dragonrail (registered trademark) (product name: Asahi Glass Co., Ltd .: trade name), GORILLA (registered trademark) Glass (product name: Corning Inc .: product name), and SCHOTT Xensation (registered trademark) Cover (shot company). Manufactured: trade name), SCHOTT Xensation (registered trademark) Cover 3D (manufactured by Shot Corporation: trade name), and the like. The composition of chemically strengthened glass is described in, for example, Patent Documents 3 and 4 described above. Further, specific examples of glass ceramics (crystallized glass) having excellent impact resistance and high hardness include Nanoceram (registered trademark) (trade name, manufactured by OHARA).

The transparent substrate 11 has a thickness of 0.2 to 0.5 mm and a surface strength by a ball-on-ring test of 170 N or more. Here, the thickness of the transparent substrate 11 is preferably 0.2 to 0.4 mm, and the BOR surface strength of the transparent substrate 11 is preferably 170 N or more. This surface strength may be satisfied by at least one main surface of the first main surface and the second main surface. By ensuring such thickness and surface strength, the impact resistance of the transparent substrate can be improved, and the optical filter can be suitable for use as a cover glass of an imaging device. About the surface strength measurement of the glass plate by a ball-on-ring test, it can evaluate as follows.
(Ball-on-ring test)
The glass plate is placed on a ring made of stainless steel having a diameter of 30 mm and the contact portion is rounded with a curvature radius of 2.5 mm, and the sphere is statically fixed in a state where the glass plate is in contact with a sphere made of steel having a diameter of 10 mm. The BOR strength F (N) measured by a ball-on-ring (BOR) test in which the load is applied to the center of the ring under load conditions is evaluated.
For example, on a receiving jig made of SUS304 (diameter 30 mm, contact portion curvature R 2.5 mm, contact portion is hardened steel, mirror finish), a glass plate as a sample is placed horizontally, and the central region of this glass plate Is pressed with a pressurizing jig (hardened steel, diameter 10 mm, mirror finish) made of SUS304 at a descending speed of 1.0 mm / min, and the breaking load (N) when the glass plate is broken is determined by the BOR strength. And the average value of 20 measurements is defined as the BOR average intensity. However, when the fracture start point of the glass plate is 2 mm or more away from the ball pressing position, it is excluded from the data for calculating the average value.
The surface strength in this specification means this BOR average strength.

(Antireflection film)
The antireflection film 14 used in the first embodiment is a film that is provided on the first main surface and prevents reflection of light in the visible range. The antireflection film 14 is an optional component in the present embodiment, and may or may not be provided.

  Examples of the antireflection film 14 include known antireflection films used in this type of optical filter, such as a dielectric multilayer film, an intermediate refractive index medium, and a moth-eye structure in which the refractive index gradually changes. Among these, the use of a dielectric multilayer film is preferable from the viewpoints of optical efficiency and productivity. The dielectric multilayer film used for the antireflection layer is obtained by alternately laminating low refractive index films and high refractive index films in the same manner as the dielectric layer film generally used for the reflection layer.

Further, the antireflection film 14, the spectral reflectance to light in the visible region, the incident angle 0 to 45 °, the average value _{R S} wavelength 420~560nm is, the incidence angle 0 to 45 °, the average value of the wavelength 570~660nm A film having a value larger than _RL is preferable. By doing in this way, the color temperature of the reflected light in the anti-reflective film 14 becomes higher than white light (6500K), and it can be set as the appearance color near bluish white. In order to obtain such a film, the antireflection film 14 preferably has a multilayer structure. By doing so, it is easy to obtain the same characteristics for the spectral reflectance of the optical filter 10.

The spectral reflectance of the optical filter 10 corresponds to the sum of Fresnel reflected light generated at the interface of materials having different refractive indexes. That is, the spectral reflectance Rt of the optical filter 10 shown in FIG. 1A is the spectral reflectance A of the antireflection film 14 formed at the interface between the transparent substrate 11 and air, and the spectrum at the interface between the transparent substrate 11 and the absorption layer 12. It depends on the reflectance B and the spectral reflectance C of the reflective layer 13 formed at the interface between the absorbing layer 12 and air. Rt is not a simple sum (A + B + C), but corresponds to the reflectance in consideration of the multiple reflections between the reflective interfaces and the spectral transmittance of the absorption layer 12, so that only the spectral reflectance calculation values A, B, and C for each interface are included. However, if the spectral reflectance of individual films or layers satisfies a predetermined condition (average value R _S and average value R _L ), the spectral reflectance of the entire optical filter 10 is also reduced. It can be adjusted to the same reflection color.

The average values R _S and R _L are obtained by forming an antireflection film 14 on the surface of the transparent substrate 11, forming a sample having a blackened back surface after roughening to become a diffusion surface, Using a photometer, the incident angle of incident light having a wavelength of 420 to 660 nm is changed from 0 to 45 ° from the antireflection film 14 side, the spectral reflectance is measured, and the average value under the above conditions may be calculated. . As for the spectral reflectance of the optical filter 10, the spectral reflectance is measured in the same manner with respect to the incident light from the antireflection film 14 side, and an average value may be calculated (at this time, the antireflection layer 14 of the antireflection layer 14). (Roughening and blacking are not required). Note that the wavelength step of the spectral reflectance is preferably 10 nm or less, and the incident angle step may be a four-point average value of 15 ° or a three-point average value of incident angles of 0 °, 30 °, and 45 °.

  Further, when the optical filter is used in an imaging apparatus such as a portable device, the antireflection film 14 is usually disposed on the outer surface side of the portable device so as to be exposed to the external environment. Therefore, since it contacts or rubs various objects, the optical characteristics of the optical filter may be deteriorated due to the contact. Therefore, in order to suppress such a decrease in optical characteristics, it is preferable that the antireflection film 14 has a high scratch resistance that is not easily damaged by contact or rubbing.

  In addition, when using sapphire for the transparent substrate 11 from the viewpoint of the strength or hardness of the base material, since it is a scratch-resistant surface that is hard to be scratched, it may be left as it is from the viewpoint of strength and the like, but sapphire has a refractive index. Since it is as large as 1.77, the Fresnel reflectivity of vertically incident light at the interface with air is 7.7%, and the optical loss is approximately twice that of ordinary glass having a refractive index of approximately 1.50. Therefore, even when sapphire is used, it is preferable to form the antireflection film 14 as described above in order to reduce residual reflection while maintaining scratch resistance.

  Among them, the antireflection film 14 having high scratch resistance is preferable, and examples of the structure and manufacturing method of such a film include those exemplified in Patent Document 3 above. Further, by forming an antifouling coating layer (referred to as AFP (anti-fingerprint)) having a thickness of less than 20 nm exemplified in Patent Document 3 on the surface of the antireflection film 14, adhesion of oily dirt such as fingerprints. It is also possible to reduce the image quality degradation of the image pickup apparatus.

A structural example of the antireflection film 14 is shown in Table 1. Here, a high refractive index transparent dielectric film Ta ₂ O ₅ and a low refractive index transparent dielectric film SiO ₂ are alternately laminated on the first main surface of sapphire, and a Sn-containing SiO ₂ film is used as a surface protective layer. A film is formed. The calculation results of the spectral reflectance when the incident angle of the antireflection film 14 is 0 °, 30 °, and 45 ° are shown in FIG. 3A by a solid line, a dotted line, and a one-dot chain line, respectively. Here, in the antireflection film 14, the spectral reflectances with incident angles of 0 °, 30 °, and 45 ° correspond to R (0), R (30), and R (45) in FIG. 3A, respectively. By adjusting the configuration of the dielectric multilayer film, it is possible to provide an antireflection film that exhibits an antireflection effect in the visible region and increases residual reflection in the short wavelength region of 420 to 560 nm as compared to the long wavelength region of 570 to 660 nm. The color of the reflected color can be adjusted, and the color can be close to bluish white.

The antireflection film 14 is made of a single-layer dielectric film having a refractive index n, and the reflection color can be changed by adjusting the film thickness d and setting the optical film thickness n × d. When the refractive index of the transparent substrate 11 is n _G and the refractive index of the atmospheric medium is n ₀ , when light with a wavelength λ is perpendicularly incident, the interface between the transparent substrate 11 and the dielectric film and the interface between the atmospheric medium and the dielectric film are used. The Fresnel amplitude reflectances r ₁ and r ₂ are r ₁ = (n _G −n) / (n _G + n) and r ₂ = (n−n ₀ ) / (n + n ₀ ). r ₁ and r ₂ interfere with a phase difference δ = 2π × 2nd / λ due to the optical path length difference 2nd, and the energy reflectivity R is R = | r ₁ + r ₂ × e ^−iδ | ² = | r ₁ −r ₂ | ² + 4r ₁ × r ₂ × cos ² (δ / 2)
Can be approximated. That is, R = | r ₁ −r ₂ | ² at a wavelength λ at which the optical film thickness nd of the dielectric film is an odd multiple of λ / 4, and a wavelength λ at which the optical film thickness nd is a natural number multiple of λ / 2. R = | r ₁ + r ₂ | ² , and the energy reflectivity R becomes a value of | r ₁ −r ₂ | ² to | r ₁ + r ₂ | ² at other wavelengths.

In the case of the antireflection film 14 in which the atmospheric medium is air and the transparent substrate is sapphire, since n ₀ = 1.0 and n _G = 1.77, the dielectric film satisfying n ₀ <n <n _G is r ₁ >. Since 0 and r ₂ > 0, the optical film thickness nd is an odd-number multiple of λ / 4, and the antireflection film has the minimum reflectance R = | r ₁ −r ₂ | ² . Further, the reflectivity R = 0 when n = (n ₀ × n _G ) ^1/2 = 1.32.

For example, if λ _G = 520 nm and the optical film thickness nd = λ _G , then λ≈5 × λ _B / 4≈3 × λ _R / 4 when λ _B ≈420 nm and λ _R ≈700 nm, so the wavelength λ _G in residual reflectance maximum, the wavelength lambda _B and lambda in _R residual reflectivity is minimized antireflection film. According incident angle increases from 0 °, wavelength of maximum reflectance and minimum reflectance is shifted to the short wavelength side, but color reflected by setting the wavelength at which nd = lambda _G green near a green-green-blue Become.

When the antireflection film 14 is a single layer of MgF ₂ shown in Table 2, the calculation results of the spectral reflectances at incident angles of 0 °, 30 °, and 45 ° are shown in FIG. 3B as solid lines, dotted lines, and alternate long and short dash lines, respectively.

At this time, in the antireflection film 14, the spectral reflectances with incident angles of 0 °, 30 °, and 45 ° correspond to R (0), R (30), and R (45) in FIG. Are 5.2%, 6.1%, and 6.1%, respectively, and the average value R _S of the entire incident angle (0 °, 30 °, and 45 °) is 5.8%. On the other hand, 2.8% respectively, the mean value of the wavelength 570~660nm, 1.0%, 1.2%, an average value _{R L} of the entire incident angle is 1.6%. Therefore, since R _S > R _L , the color temperature of the reflected light of the anti-reflection film 14 is higher than that of white light, and the appearance of the appearance color close to blue-greenish white is exhibited.

(Absorption layer)
The absorption layer 12 used in the first embodiment is a layer that is provided on the second main surface of the transparent substrate 11 and has a near-infrared absorbing ability that absorbs at least light in the near-infrared region. The absorption layer 12 is for bringing light received by a solid-state imaging device, which will be described later, close to human visual sensitivity, and has a function of correcting spectral sensitivity at a wavelength of 650 to 720 nm which is a long wavelength side in the visible region. Since the absorption layer 12 has a spectral absorption characteristic that does not depend on the incident angle, the absorption layer 12 has an effect of making it difficult to cause color unevenness in the captured image.

  Here, the absorption layer 12 can have the same configuration as a known absorption layer. As an example of such an absorption layer, for example, it is formed of a transparent resin containing a single layer structure absorption layer, a near infrared absorber and a near ultraviolet absorber formed of a transparent resin containing a near infrared absorber. An absorption layer having a single layer structure, a multilayer structure in which a layer formed of a transparent resin containing a near infrared absorber and a layer formed of a transparent resin containing a near ultraviolet absorber are laminated, and the above Examples thereof include an absorption layer obtained by combining layers of near-infrared absorbing glass and the like. Such an absorption layer 12 can be obtained by using, for example, the materials and configurations exemplified in Patent Document 1.

  Hereinafter, as the absorption layer 12, an absorption layer having a single layer structure formed of a transparent resin containing a near infrared absorber and a near ultraviolet absorber will be described. Such an absorption layer 12 can be obtained by applying a coating solution in which a near-infrared absorber and a near-ultraviolet absorber are dissolved in a transparent resin on the transparent substrate 11, drying and curing.

  At this time, as the near-infrared absorber, a known near-infrared absorber can be used, and for example, a near-infrared absorbing dye composed of a squarylium compound represented by the following general formula (F1) is preferable.

ただし、式（Ｆ１）中の記号は以下のとおりである。
Ｒ^１およびＲ^２は互いに連結して窒素原子と共に５員環または６員環の環構成原子として酸素原子を含んでもよい複素環（環Ａ）を形成しているか、Ｒ^２およびＲ^５は互いに連結して窒素原子と共に５員環または６員環の環構成原子として酸素原子を含んでもよい複素環（環Ｂ）を形成している。複素環を形成していない場合の、Ｒ^１およびＲ^５は、それぞれ独立して、水素原子、フッ素原子、臭素原子、置換基を有していてもよい炭素数１〜６のアルキル基、置換基を有していてもよいアリル基、置換基を有していてもよい炭素数６〜１０のアリール基または置換基を有していてもよい炭素数７〜１１のアルアリール基を示す。アルキル基は、直鎖状、分岐鎖状、環状のいずれであってもよい。

However, the symbols in formula (F1) are as follows.
R ¹ and R ² are connected to each other to form a heterocyclic ring (ring A) that may contain an oxygen atom as a 5-membered or 6-membered ring constituent atom together with the nitrogen atom, or R ² and R ⁵ are They are connected to form a heterocyclic ring (ring B) that may contain an oxygen atom as a 5-membered or 6-membered ring constituent atom together with the nitrogen atom. When not forming a heterocyclic ring, R ¹ and R ⁵ are each independently a hydrogen atom, a fluorine atom, a bromine atom, an optionally substituted alkyl group having 1 to 6 carbon atoms, or a substituent. An allyl group which may have a group, an aryl group having 6 to 10 carbon atoms which may have a substituent or an araryl group having 7 to 11 carbon atoms which may have a substituent are shown. The alkyl group may be linear, branched or cyclic.

R ⁴ and R ⁶ are each independently a hydrogen atom, —NR ⁷ R ⁸ (R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or —C (= ^O) -R ^{9 (R} 9 is an alkyl group or aryl group having carbon atoms of 6 to 10 optionally having a carbon number of 1-20 which may have a substituent)) shows a.
R < ³ > shows a hydrogen atom or a C1-C6 alkyl group each independently.

  In the absorption spectrum in the wavelength range of 400 to 1000 nm, a transparent resin is used so that the near infrared absorption dye having an absorption peak wavelength of 700 nm is used, the transmittance at 700 nm is 2% or less, and the transmittance at 650 nm is about 50%. The near-infrared absorbing dye concentration is set.

  Various resin materials can be used as a transparent resin containing a near infrared absorber or a near ultraviolet absorber. For example, acrylic resin, epoxy resin, ene thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin, polyarylene ether phosphine oxide resin, polyimide resin, polyamide Examples include imide resins, polyolefin resins, cyclic olefin resins, and polyester resins. Transparent resin may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The absorption layer made of a transparent resin is set to a film thickness in which the absorbent is dispersed at a uniform concentration and a uniform spectral transmittance is obtained in the effective plane. Although depending on the transparent resin material and the film forming method, the film thickness is preferably 1 to 50 μm, and more preferably 2 to 20 μm from the viewpoint of reducing the amount of material used and reducing the influence of contained foreign substances.

  Prepare a coating solution that stirs and dissolves the absorbent at room temperature and disperses it in a transparent resin at a uniform concentration. After applying the coating solution to a uniform thickness on a transparent substrate by spin coating or die coating, heat is applied. It is good also as an absorption layer by making it dry. Moreover, you may use energy-beam curable resin mentioned later.

  An example of the spectral transmittance of an absorption layer having a thickness of 10 μm obtained using a transparent resin containing no near-infrared absorbing pigment as described above (not containing a near-ultraviolet absorber) is shown by a solid line in FIG. 5A. The spectral transmittance shown here is a calculation example in which Fresnel reflection at the air interface is corrected to obtain internal transmittance. A dotted line is a calculated value of spectral transmittance when reciprocating through the absorption layer.

The optical properties of the absorption layer are expressed by a complex refractive index n-iκ using a refractive index n and an extinction coefficient κ, and absorb light according to the wavelength (λ) dependence of the extinction coefficient κ inherent to the absorbent. Along with this, the spectral transmittance changes. When the thickness of the absorbent layer in which the absorbent is uniformly dispersed in the thickness direction in the transparent resin at the absorbent concentration C is L, the spectral transmittance T (λ) of the absorbent layer is T (λ) = exp ( −4πκL / λ). Here, α = 4πκ / λ is an absorption coefficient. When expressed in common logarithm, T (λ) = 10− ^βL , and β is a value obtained by multiplying α by log ₁₀ (e) = 0.434. It corresponds to. Here, the absorbance is represented by −log ₁₀ {T (λ)} = βL. The absorption coefficients α and β vary depending on the absorbent concentration C in the absorption layer. That is, the spectral transmittance of the absorption layer can be adjusted by the absorbent concentration C in the absorption layer and the thickness L of the absorption layer, and the same applies when a plurality of absorbents are included. Therefore, the forward spectral transmittance of an absorption layer made of a transparent resin having a film thickness L = 10 μm containing a near-infrared absorbing dye made of a squarylium compound at a predetermined concentration C, and the round trip spectral transmission corresponding to a film thickness L = 20 μm. A rate is calculated.

  The absorption layer 12 may be an absorption layer (near infrared and near ultraviolet absorption layer) containing a near ultraviolet absorbing dye as a near ultraviolet absorber. In the spectral sensitivity of a solid-state imaging device described later, it is effective to use a near-ultraviolet absorber in order to block light having a wavelength of 350 to 400 nm that does not reach human visibility. The absorption layer 12 containing the near-ultraviolet absorber has a spectral absorption characteristic that does not depend on the incident angle, and thus has an effect of making it difficult to cause color unevenness in the photographed image.

  Here, the near-ultraviolet absorbing dye used as the near-ultraviolet absorber and the transparent resin material containing the dye can have the same configuration as a known near-ultraviolet absorbing layer. The materials and configurations exemplified in Document 2 can be used.

  Near UV absorbers include merocyanine dyes, benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, triazine UV absorbers, oxanilide UV absorbers, nickel A complex salt type ultraviolet absorber, an inorganic type ultraviolet absorber, etc. are mentioned.

  Specific examples of the near ultraviolet absorber include H.I. W. Examples include Sands SDA 3382 and MSA 3144, QCR Solutions UV386A and UV386B and UV386A, Chiba TINUVIN479 (trade name), and the like. All of these have the absorption maximum wavelength in the wavelength region of 370 to 405 nm in the above-described absorption spectrum, almost no light absorption in the visible region of 440 to 700 nm, and relatively steep in the wavelength region of 390 to 420 nm. Since the transmittance change can be obtained, it is suitable as a near-ultraviolet absorber for the optical filter of the present embodiment.

  In addition, in the absorption spectrum of a wavelength range of 400 to 1000 nm, the spectral transmission of an absorption layer having a film thickness of 10 μm obtained using a transparent resin containing a near ultraviolet absorber having an absorption peak wavelength of 388 nm (not containing a near infrared absorber). An example of the rate is shown in FIG. The spectral transmittance shown here is a calculation example in which Fresnel reflection at the air interface is corrected to obtain internal transmittance. A dotted line is a calculated value of spectral transmittance when reciprocating through the absorption layer.

  Here, the near-UV absorber concentration in the transparent resin was set so that the transmittance at a wavelength of 388 nm was 5% or less and the transmittance at a wavelength of 400 nm was about 50%.

  And, when the absorption layer has a near infrared absorption ability and a near ultraviolet absorption ability (when the absorption layer contains a near infrared absorption agent and a near ultraviolet absorption agent in the same transparent resin, the near infrared absorption agent When the layer made of the transparent resin and the layer made of the transparent resin containing the near-ultraviolet absorber are laminated, the spectral transmittance of the absorption layer corresponds to the product of FIGS. 5A and 5B. It can be approximated by a 5C solid line (outward path) and a dotted line (reciprocating).

(Reflective layer)
The reflective layer 13 used in the first embodiment of the present invention is a reflective layer that transmits visible light and reflects ultraviolet and near-infrared light. The reflective layer 13 can have the same configuration as a known reflective layer.

  As the reflective layer 13, the transmittance of light having a wavelength of 420 to 600 nm, which is a visible region of the optical filter 10, is maintained at 90% or more, and transmission of light having a wavelength of 700 to 1100 nm, which is the near infrared region of the optical filter 10. It is preferable to block by reflection so that the rate is 10% or less.

  At this time, the transmittance of light in the visible region is preferably 95% or more, and the transmittance of light in the near infrared region is preferably 5% or less, more preferably 2% or less.

  In the optical filter 10 shown in FIG. 1A, the reflective layer 13 covers the absorption layer 12 and has a configuration in which the surface is formed at a position (outermost surface) in contact with air. Further, the second main surface of the transparent substrate 11 is shown. It may be formed on top. In that case, a reflective layer 13a that reflects light of 950 to 1100 nm which is a long wavelength region in the near infrared region at an incident angle of 0 ° is formed on the second main surface of the transparent substrate 11, and a short wavelength in the near infrared region is formed. A reflective layer 13b that reflects light having a wavelength of 700 to 950 nm is formed at a position (outermost surface) where the absorption layer 12 is in contact with air. With such a configuration, it is possible to block the near-infrared band with a wavelength of 700 to 1100 nm by synthesizing the spectral transmittances of the reflective layer 13a and the reflective layer 13b.

  Since the reflective layer 13 has such a separation configuration, even when the reflection wavelength band of the reflective layer 13a is shifted to the short wavelength side when the incident angle is increased, the visible region does not reach 700 nm or less. Wavelength side reflection does not increase. Further, even if the reflection wavelength band of the reflection layer 13b is shifted to the short wavelength side, the reflected light of the reflection layer 13b in the transition wavelength region between the visible region and the near infrared region is absorbed by the absorption layer 12 by reciprocating through the absorption layer 12. It is preferable because the reflected color does not have a low color temperature.

Such a reflective layer 13 (including 13a and 13b) includes an optical film thickness (refractive index n × film) of a transparent dielectric film having a high refractive index n _{H and} a transparent dielectric film having a low refractive index n _L alternately. It is constituted by a dielectric multilayer film laminated so that the thickness d) is approximately equal to or less than the wavelength λ of the reflection wavelength band. Examples of the configuration and spectral transmittance of the reflective layer include those exemplified in Japanese Patent No. 6202229. Note that a metal film having a thin film thickness that does not significantly reduce the transmittance in the visible region may be used as a component of the multilayer film.

Here, the reflective layer 13, as a spectral reflectance, the incident angle 0 to 45 °, the average value _{R S} wavelength 420~560nm is, the incidence angle 0 to 45 °, greater than the average value _{R L} of the wavelength 570~660nm It is preferable to have a multilayer film structure that provides a value. By doing so, it is easy to obtain the same characteristics with respect to the spectral reflectance of the optical filter 10, and the reflected light can be made to have an appearance color close to bluish white.

Table 3, on the transparent resin layer having a refractive index _n s = 1.64 at a wavelength of 840 nm, a SiO ₂ film of TiO ₂ film and a low refractive index _n L = 1.45 of the high refractive index _n H = 2.25 An example of the multilayer film configuration of the reflective layers 13 in which 49 layers are alternately stacked is shown.

  The calculated values of the spectral transmittance of the reflection layer having the 49-layer multilayer structure are shown in FIG. 7 with an incident angle of 0 ° as a solid line and an incident angle of 30 ° as a dotted line. The reflection bands having a transmittance of 50% or less at a wavelength of 350 to 1100 nm shift from 350 to 398 nm and 739 to 1100 nm at an incident angle of 0 ° to 350 to 386 nm and 708 to 1100 nm at an incident angle of 30 °, respectively. The average transmittances in the visible transmission wavelength range of 400 to 700 nm are 98.5% and 97.7% at incident angles of 0 ° and 30 °, respectively.

The optical filter 10 obtained as described above has an incident angle of 0 to 45 ° and an average value R _{S of} wavelengths of 420 to 560 nm with respect to the incident light from the antireflection film 14 side. It is larger than the average value R _L of 45 ° and wavelengths of 570 to 660 nm. By doing in this way, the color temperature of the reflected light in the optical filter 10 becomes higher than white light (6500K), and it can be set as the appearance color near bluish white.

In order to satisfy this characteristic, as described above, in either the reflective layer 13 or the antireflection film 14 having the absorption layer 12 arranged on the light incident side, the equivalent characteristic (the average value R _S is the average value R _The reflection layer 13 having the absorption layer 12 and the antireflection film 14 have the same characteristics (the average value R _S is greater than the average value R _L ). It is more preferable to have it.

(Second Embodiment)
An optical filter 20 shown in FIG. 1B includes a transparent substrate 11 having an antireflection film 14 on a first main surface, and an absorption layer 12 having a near-infrared absorptivity on a second main surface of the transparent substrate 11. This is a configuration example of the optical filter 20 in which the near-infrared absorbing glass 12c and the reflective layer 13 are laminated in this order. That is, the optical filter is configured by adding the near-infrared absorbing glass 12c between the absorption layer 12 and the reflection layer 13 to the optical filter 10 of the first embodiment.

  Here, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. Only the differences will be described below.

The near-infrared absorbing glass 12c used here may be a known near-infrared absorbing glass obtained by adding CuO or the like to a fluorophosphate glass or a phosphate glass. The “phosphate glass” includes silicic acid phosphate glass in which a part of the glass skeleton is composed of SiO ₂ .

  The maximum absorption wavelength of the infrared absorbing glass containing CuO is in the near infrared region of 850 to 950 nm, and shows absorption in a wide wavelength region of 620 to 1100 nm. Therefore, the minimum transmittance wavelength can be adjusted by adjusting the content of CuO. Becomes an absorption layer having a spectral transmittance of about 900 nm and a spectral transmittance of 50% or less in a wide near infrared region. As specific composition examples and product examples of the absorption glass containing CuO, for example, those exemplified in Patent Document 2 can be used.

  Here, although the thickness of the near-infrared absorbing glass 12c depends on the constituent materials, it is preferably 0.03 to 1 mm, and more preferably 0.05 to 0.5 mm from the viewpoint of handling and thinning.

  In this way, by combining the near-infrared absorbing glass 12c with the absorbing layer 12, incident light in the near-infrared wavelength region of 750 to 1100 nm that is not absorbed only by the absorbing layer 12 can be absorbed. Along with the light shielding by the reflection band, the near-infrared stray light component reaching the imaging lens 23 and the solid-state imaging device 21 is reduced. As a result, a clear image can be obtained. Moreover, it is possible to effectively correct the spectral sensitivity of the human eye from the spectral transmittance of the near-infrared absorbing glass at a wavelength of 650 to 720 nm.

(Third embodiment)
The optical filter 30 shown in FIG. 1C includes a transparent substrate 11 provided with an antireflection film 14 on a first main surface, and a near-ultraviolet absorber containing a near-ultraviolet absorber on the second main surface of the transparent substrate 11. This is a configuration example of the optical filter 30 in which a layer 12a, an infrared absorption glass 12c, an absorption layer 12b containing a near infrared absorber, and a reflection layer 13 are laminated in this order. That is, with respect to the optical filter 10 of the first embodiment, instead of the absorption layer 12, a layer (12b, 12c) having near infrared absorption ability and a layer (12a) having near ultraviolet absorption ability are respectively provided. It is an optical filter provided with a plurality of layer structures with separated functions.

  Here, the same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and the description thereof is omitted. Only the differences will be described below.

  The near-ultraviolet absorbing layer 12a is made of a transparent resin containing a near-ultraviolet absorber. The near-ultraviolet absorbing layer 12a is a near-ultraviolet absorbing layer 12a made of a transparent resin containing a near-ultraviolet-absorbing dye that corrects a wavelength of 350 to 400 nm to the spectral sensitivity of the human eye in the spectral sensitivity of a solid-state imaging device described later. . This near-ultraviolet absorbing layer 12a also functions as an adhesive layer that bonds the transparent substrate 11 and the near-infrared absorbing glass 12c.

  Moreover, about the light of a near infrared region, the light of wavelength 650-720 nm mentioned later is formed by combining the absorption layer 12b which consists of transparent resin containing the near-infrared absorption pigment | dye, and the near-infrared absorption-type glass 12c. Can effectively correct the spectral sensitivity of the eye.

  And, in order to block light with a wavelength of 350 to 400 nm, in particular, by forming the near ultraviolet absorption layer 12a, the near infrared absorption layer 12b and the near infrared absorption glass 12c as different layers, respectively. Since the necessary content of the near-ultraviolet absorbing dye can be adjusted, a sufficient blocking property can be secured as compared with the case where the near-infrared absorber and the near-ultraviolet absorber are contained in the same resin.

  Here, as for the transparent resin used for the near-ultraviolet absorption layer 12a, the refractive index of the hardened | cured material has preferable 1.45 or more. This refractive index is more preferably 1.5 or more, and particularly preferably 1.6 or more. The upper limit of the refractive index of the transparent resin is not particularly limited, but is preferably about 1.72 in view of availability.

  Specific examples of the transparent resin include thermoplastic resins such as polycarbonate (PC) and cycloolefin (COP), polyimide (PI), polyetherimide (PEI), polyamide (PA), and polyamideimide (PAI). And an energy ray curable resin such as acrylic or epoxy can be used.

  When using a thermosetting resin or energy ray curable resin, add a near-ultraviolet absorber at the stage of a polymerization precursor compound (hereinafter also referred to as a polymerizable compound) such as an oligomer or monomer, and then cure. Good. Among these, from the viewpoint of moldability, an energy ray curable resin substantially free of a solvent is preferably used. By using the energy ray curable resin, the cover base material can be covered and cured, so that the flatness of the surface of the resin material can be increased.

  Examples of the energy ray curable resin include an ultraviolet curable resin that is cured by irradiation with ultraviolet rays. Such a polymerizable compound can be used without particular limitation as long as it is a component that is cured by a polymerization reaction to form a cured product. For example, a radical polymerization type curable resin, a cationic polymerization type curable resin, and a radical polymerization type curable compound (monomer) can be used without particular limitation. Among these, a radical polymerization type curable compound (monomer) is preferable from the viewpoint of polymerization rate and moldability described later. Radical polymerization type curable resins include (meth) acryloyloxy groups, (meth) acryloylamino groups, (meth) acryloyl groups, allyloxy groups, allyl groups, vinyl groups, vinyloxy groups, etc. Examples thereof include a resin having a group having a bond.

  In the case of performing ultraviolet curing, it is preferable to use a photopolymerization initiator, for example, light appropriately selected from acetophenones, benzophenones, benzoins, benzyls, benzoin alkyl ethers, benzyldimethyl ketals, thioxanthones, and the like. A polymerization initiator is preferably used. A photoinitiator can be used 1 type or in combination of 2 or more types.

  The amount of the photopolymerization initiator is preferably 0.01% by mass to 5% by mass, and particularly preferably 0.1% by mass to 2% by mass with respect to the total amount of the polymerizable composition.

  In the present embodiment, the polymerizable compound is not particularly limited, but ethoxylated o-phenylphenol acrylate, 2- (perfluorohexyl) ethyl methacrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate. , Tricyclodecane (meth) acrylate, tricyclodecane methanol (meth) acrylate, tricyclodecane ethanol (meth) acrylate, 1-adamantyl acrylate, 1-adamantyl methanol acrylate, 1-adamantyl ethanol acrylate, 2-methyl-2- Monofunctional compounds such as adamantyl acrylate, 2-ethyl-2-adamantyl acrylate, 2-propyl-2-adamantyl acrylate, dicyclopentanyl acrylate, and 9,9-bis 4- (2-acryloyloxyethoxy) phenyl] fluorene, diethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, isobornyl di (meth) acrylate, tricyclodecane di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, tricyclodecane diethanol di (meth) acrylate, adamantane diacrylate, adamantane dimethanol diacrylate, tri Bifunctional compounds such as cyclodecane dimethanol diacrylate, trifunctional compounds such as trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate What tetrafunctional compounds, hexafunctional compounds such as dipentaerythritol hexa (meth) acrylate.

  The polymerizable compound may contain one type or two or more types. When only a monofunctional compound is used, cohesive failure may occur at the time of mold release after molding. Therefore, it is preferable to include a bifunctional or higher polyfunctional compound. The polyfunctional compound in the polymerizable compound is preferably 1% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 80% by mass or less. When the amount of the polyfunctional compound is less than 1% by mass, the effect of improving the cohesive failure is insufficient, and when it exceeds 90% by mass, shrinkage after polymerization may be a serious problem.

  Moreover, the polymeric compound which raise | generates a ring-opening reaction like an epoxy group other than said functional group which has a carbon-carbon unsaturated double bond can also be used. Since such a compound has a small polymerization shrinkage, not only can precision molding be performed by a mold, but also warpage can be reduced. Although not specifically illustrated, in this case as well, since a monofunctional compound alone may cause cohesive failure at the time of mold release after molding, it is preferable to include a bifunctional or higher polyfunctional compound. The polyfunctional compound in the polymerizable compound group is preferably 1% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and 80% by mass or less.

  Moreover, you may use OCA (Optical Clear Adhesive) of a sheet-like adhesive tape used as an adhesive agent for the display part of a display, or liquid ultraviolet curable resin OCR (Optical Clear Resin). The transparent resin used for the adhesive layer is preferably a material that is optically uniform and transparent in the visible wavelength range of 420 to 680 nm, has no adhesion failure such as peeling or foaming, and does not change in dimensions under various usage environments.

  As described in the absorption layer 12 of the optical filter 10 described in the first embodiment, the near-infrared absorption layer 12b can be provided by containing a near-infrared absorber in a transparent resin. Basically, it is provided as the same structure as the absorption layer 12 in the first embodiment, but in this embodiment, the near-infrared absorption layer 12b is optically contained without containing a near-ultraviolet absorber. Is provided as a layer only having near-infrared absorption ability.

  In this way, when a near-infrared absorber and a near-ultraviolet absorber are contained in the same transparent resin, there is a problem that a high absorption light-shielding property cannot be obtained because the content is restricted, specifically, the wavelength When a transparent resin containing a near-infrared absorbing dye necessary for correcting the spectral sensitivity of human eyes to 650 to 720 nm is used, the content of the near-ultraviolet absorbing dye may be limited. By using different layers, it is possible to solve the problem that the absorptivity at a wavelength of 350 to 400 nm is lowered and the blocking property is insufficient.

(Fourth embodiment)
In the fourth embodiment, an antireflection film is further formed between the transparent substrate and the absorption layer. In FIG. 1D, the transparent substrate 11 provided with the antireflection film 14 on the first main surface and the second antireflection film 15 on the second main surface, and on the second antireflection film 15, This is a configuration example of an optical filter 40 in which a near-ultraviolet absorbing layer 12a, a near-infrared absorbing glass 12c, a near-infrared absorbing layer 12b, and a reflecting layer 13 are stacked in this order. That is, the third embodiment is characterized in that an antireflection film 15 is provided between the transparent substrate 11 and the near ultraviolet absorption layer 12a.

In the optical filter 40, the second antireflection film 15 is provided for the purpose of reducing Fresnel reflection occurring at the interface when the difference in refractive index between the transparent substrate 11 and the near-ultraviolet absorbing layer 12a is large. The second antireflection film 15 has an incident angle of 0 to 45 ° and a wavelength of 420 so that the reflected light of the optical filter has an appearance color close to bluish white. mean value _{R S} of ~560nm is, the incidence angle 0 to 45 °, a multilayer film structure comprising a larger value than the average value _{R L} of the wavelength 570～660Nm.

  The second antireflection film 15 is included in the near ultraviolet region having a wavelength of 350 to 410 nm or in the near infrared region having a wavelength of 800 to 1100 nm among incident light having a wavelength of 350 to 1100 nm that is transmitted through the antireflection film 14 and the transparent substrate 11. It may have a function of wavelength selective reflection having a reflection band. As a result, since the reflection bandwidth which the reflection layer 13 bears decreases, the film thickness and the number of layers of the reflection layer can be reduced.

A configuration example of the second antireflection film 15 is shown in Table 4. Here, the high refractive index transparent dielectric film Ta ₂ O ₅ and the low refractive index transparent dielectric film SiO ₂ are alternately laminated on the second main surface of sapphire. FIG. 4A shows the calculation results of the spectral reflectances of the second antireflection film 15 with the incident angles of 0 °, 30 °, and 45 ° as a solid line, a dotted line, and an alternate long and short dash line, respectively. By adjusting the configuration of the dielectric multilayer film, the antireflection film exhibits an antireflection effect in the visible region, and becomes an antireflection film in which the residual reflection in the short wavelength region of 420 to 560 nm is larger than the long wavelength region of 570 to 660 nm. The reflected color is close to bluish white.

When the atmospheric medium corresponding to the second antireflection film 15 is a transparent resin and the transparent substrate is sapphire, for example, when n ₀ = 1.52 and n _G = 1.77, the refractive index difference between n ₀ and n _G is Since it is small, the Fresnel reflectivity is as low as 1% or less, and there is almost no effect of the antireflection film. When a single-layer dielectric film is formed to control the reflection color, a color reflection film is formed using a dielectric film satisfying n ₀ <n _G <n so that the reflectance in a specific wavelength region is increased. Becomes effective. Here, since r ₁ = (n _G −n) / (n _G + n) <0 and r ₂ = (n−n ₀ ) / (n + n ₀ )> 0, the energy reflectance R = | r ₁ −r ₂ | ² + 4r ₁ × r ₂ × cos ² (δ / 2) is the minimum reflectance R = | r ₁ + r ₂ | ² at the wavelength λ at which the optical film thickness nd is a natural number multiple of λ / ² , the optical film The maximum reflectance R = | r ₁ −r ₂ | ² is obtained at a wavelength λ at which the thickness nd is an odd multiple of λ / 4.

For example, as shown in Table 5, when ZrO ₂ (n = 2.06) is used as the dielectric film and the film thickness d is λ _G = 540 nm and the optical film thickness nd = 3 × λ _G / 4, the wavelength It is an alternative film (color reflection film) for the antireflection film 15 having a maximum reflectance at λ _G and a minimum reflectance at wavelengths λ _B ≈420 nm and λ _R > 700 nm. FIG. 4B shows the calculation results of the spectral reflectance when the incident angles are 0 °, 30 °, and 45 °, as a solid line, a dotted line, and a one-dot chain line, respectively. Therefore, by setting the wavelength λ _{G at} which nd = 3 × λ _G / 4 is set in the vicinity of green, the reflected color becomes green to patina. By setting the film thickness d corresponding to other wavelength lambda _G, it can be a different reflection colors color reflection film.

At this time, in the antireflection film (color reflection film) 15, the spectral reflectances with incident angles of 0 °, 30 °, and 45 ° correspond to R (0), R (30), and R (45) in FIG. 4B. , 3.5% average wavelength 420~560nm respectively, 4.4%, 5.5%, total incidence angle (0 °, 30 °, 45 °) is an average value _{R S} of a 4.5% . On the other hand, 3.5% respectively, the mean value of the wavelength 570~660nm, 2.5%, 1.8%, an average value _{R L} of the entire incident angle is 2.5%. Therefore, since R _S > R _L , the color temperature of the reflected light of the anti-reflection film 15 is higher than that of white light, and the design of an appearance color close to blue-greenish white is exhibited.

  As described above, the first to fourth embodiments have been described as the embodiments of the present invention. In each embodiment, the transparent resin used for forming the absorption layer absorbs in the visible wavelength range of 420 to 680 nm. You may contain the color pigment | dye which has. Here, the color pigment is preferably an absorption layer 12 containing a near ultraviolet absorber or a near ultraviolet absorption layer 12a.

  When the color pigment is used in this manner, the reflected color of the optical filter can be adjusted, so that when used as a cover glass for a portable device or the like, the appearance can be adjusted to a design that is not uncomfortable with the casing of the portable device. .

  By including a color pigment as described above, the reflected colors of the optical filters 10 to 40 can be colored. Here, in order for a human to recognize the color of a specific wavelength, the antireflection layer 14 is based on the premise that the light absorption rate of a specific color wavelength is lower than the light absorption rate of other wavelength regions in the visible range. Visible light entering through the transparent substrate 11 and the absorbing layer 12 (including the near-ultraviolet absorbing layer 12a, the near-infrared absorbing glass 12c, and the near-infrared absorbing layer 12b) are reflected by the reflecting layer 13 and again absorbed. The human perceives the color through the transparent substrate 11 (including the near-ultraviolet absorbing layer 12a, the near-infrared absorbing glass 12c, and the near-infrared absorbing layer 12b). When the residual reflectance of the reflective layer 13 is constant in the visible wavelength range, the spectral transmittance that reciprocates through the absorption layer 12 (including the near ultraviolet absorption layer 12a, the near infrared absorption glass 12c, and the near infrared absorption layer 12b) is colored. Determine the color of the wavelength.

  The color pigment that is the coloring material may be a dye dissolved in the resin material or an organic pigment dispersed in the resin material. It can be appropriately selected according to demands such as durability and glossiness.

As the organic pigment, known organic pigments can be used. For example, Reference 1 (Jiro Aihara, supervised by Okura Laboratory, “Technology and Application Development of Functional Pigments”, CMC Publishing Co., Ltd., September 2004, The pigment described in p.246) can be appropriately used. At that time, a plurality of pigments can be added to the resin material for the purpose of adjusting the observed color.
Here, the three colors of red, green, and blue will be described below by exemplifying coloring materials.

  As the red coloring material, coloring materials such as anthracene, diketopyrrolopyrrole, quinacridone, azo (bisazo), xanthene, perylene, and anthraquinone can be used.

  Examples of the diketopyrrolopyrrole group include pigment red 254, pigment red 255, pigment red 256, pigment red 270, pigment red 272, pigment orange 71, pigment orange 73, and the like. Examples of the quinacridone series include pigment red 122, pigment red 202, pigment red 206, pigment red 207, pigment red 209, pigment orange 48, pigment orange 49, and the like. As azo (bisazo), pigment red 17, pigment red 21, pigment red 22, pigment red 23, pigment red 31, pigment red 32, pigment red 37, pigment red 38, pigment red 60, pigment red 112, pigment red 112 114, pigment red 144, pigment red 146, pigment red 150, pigment red 166, pigment red 187, pigment red 188, pigment red 214, pigment red 220, pigment red 221, pigment red 253, pigment red 266, pigment red 268, pigment red 269 and the like. Examples of xanthene compounds include pigment red 81 and pigment red 169. Examples of the perylene system include pigment red 123, pigment red 149, pigment red 178, pigment red 179, pigment red 190, pigment red 224, and pigment red 242. Examples of the anthraquinone group include pigment red 168, pigment red 177, and pigment red 216.

  As the green coloring material, phthalocyanine, naphthoquinone, anthracene, triarylmethane, and the like can be used. Moreover, it is good also as green by mix | blending a yellow coloring material and a blue coloring material.

  Examples of the phthalocyanine series include pigment green 7, pigment green 36, and pigment green 58. Examples of the naphthoquinone type include pigment green 8. Examples of anthracene include pigment green 47 and pigment green 54. Examples of triarylmethanes include pigment green 1 and pigment green 4.

  Examples of the blue coloring material include triarylmethane, phthalocyanine, and anthraquinone.

  Examples of triarylmethanes include pigment blue 1, pigment blue 9, pigment blue 24, pigment blue 56, and pigment blue 61. Examples of the phthalocyanine series include pigment blue 15 and pigment blue 16. Examples of the anthraquinone group include pigment blue 60.

  FIG. 6A shows an example of spectral transmittance of a red colored resin material (hereinafter also referred to as R resin), a green colored resin material (hereinafter also referred to as G resin), and a blue colored resin material (hereinafter also referred to as B resin). Represented by “R”, “G”, and “B”, respectively. The red colored resin material is acryloyl morpholine and tricyclodecane dimethanol diacrylate, the green colored resin material is acryloyl morpholine and tricyclodecane dimethanol diacrylate, and the blue colored resin material is acryloyl morpholine and tricyclodehydride. Using candimethanol diacrylate, the content in the resin material in which each colored resin material is dispersed and the thickness of the resin material are adjusted so that the minimum transmittance in the visible region of 400 to 700 nm is 2% or less.

  Although the ratio (content rate) of the coloring material in the resin material of the absorption layer 12 and the near-ultraviolet absorption layer 12a depends on the magnitude of absorption per weight of the coloring material to be added and the thickness of the resin material serving as a binder, If the rate is small, the desired color does not appear, which is not preferable. Moreover, when there is much content rate, since the image light of a specific wavelength range falls within the visible wavelength range which permeate | transmits the optical filters 10-40 and the imaging lens 23, and injects into the solid-state image sensor 21, it is unpreferable.

  For example, the average transmittance in the visible wavelength region of the wavelength of 420 to 680 nm of the absorbing layer and the near ultraviolet absorbing layer is 90% or more, preferably 95% or more, and the minimum transmittance in the specific wavelength region accompanying light absorption of the coloring material is 70. The content rate of the coloring material is adjusted so as to be in the range of ˜90%. In addition, it is preferable that the content of the coloring material in which the average transmittance in the specific wavelength region is 5% or more lower than the average transmittance in the visible wavelength region excluding the specific wavelength region because a desired color is recognized. Usually, the content is 0.1% by mass to 5% by mass.

  In the R resin, G resin, and B resin described above, the content of the coloring material is adjusted so that the minimum transmittance in the visible region of 400 to 700 nm is about 90%. At this time, when the visible region of 400 to 700 nm is transmitted through the colored resin layer and reflected by the reflecting surface having a reflectance of 10% and is transmitted through the colored resin layer again and the reflected light is detected, the spectral reflectance calculation result Is shown in FIG. 6B. The R resin has a maximum reflectance of about 10% in the red wavelength range of 600 to 700 nm, the G resin has a maximum reflectance of about 9.5% in the green wavelength range of 500 to 550 nm, which has high visibility, and the B resin has a maximum reflectance of 450%. The maximum reflectance is approximately 10% in the blue wavelength region of ˜500 nm.

  That is, by including a coloring material in the resin material of the absorption layer 12, the reflected color visually recognized in the imaging apparatus of the present embodiment is the spectral characteristic of the reflecting surface such as a cover glass provided with an optical filter function. Can be adjusted independently. Here, the reflection color can generate any appearance color by adjusting the content of the R resin, G resin, and B resin described above.

  The optical function required for the optical filter is that the incident light in the visible range where the human eye is sensitive transmits with little loss, and the human eye is insensitive, but the solid-state imaging device 21 has sensitivity in the near ultraviolet range and near This is to block incident light in the infrared region, and in the wavelength region, it is required to block the wavelength bands of 350 to 400 nm and 700 to 1100 nm. The visible wavelength range of 420 to 620 nm, where the visibility is high, maintains particularly high transmittance, and the spectral transmittance close to the visibility characteristic where the transmittance gradually decreases in the visible wavelength range of 620 to 680 nm is a point of color reproducibility. Is preferable.

(Optical characteristics of optical filter)
Next, on the sapphire substrate 11, an absorption layer 12 (absorption layer in which a near ultraviolet absorber and a near infrared absorber are contained in the same transparent resin) whose spectral transmittance is illustrated in FIG. The optical characteristics of the optical filter 10 having the laminated structure of FIG. 1A in which the reflective layer 13 illustrating the transmittance was formed were examined. FIG. 8 shows a calculation result of the spectral transmittance for the incident light from the sapphire substrate 11 side with respect to the optical filter 10. The solid line corresponds to an incident angle of 0 °, and the dotted line corresponds to an incident angle of 30 °. Note that the reflectance of the antireflection film 14 formed on the first main surface of the sapphire substrate 11 is assumed to be zero, and its influence is ignored.

  From FIG. 8, the transmission of incident light in the near ultraviolet wavelength region of approximately 380 nm or less and the near infrared wavelength region of approximately 690 to 1100 nm is blocked, and the incident light in the visible wavelength region of approximately 420 to 600 nm is transmitted with a transmittance of 90% or more. To do. Further, the optical filter 10 having a wavelength of 50% transmittance of about 400 nm and about 650 nm, an incident angle of 0 to 30 °, and almost no change in spectral transmittance is obtained.

  Next, the absorption glass 12c having the near-infrared absorbing layer 12b and the reflecting layer 13 and the second main surface of the transparent substrate 11 having the antireflection film 14 on the first main surface are absorbed by near-ultraviolet rays. The optical characteristics of the optical filter 30 having the laminated structure of FIG. 1C bonded by the layer 12a were examined. FIG. 10 shows the calculation result of the spectral transmittance with respect to the incident light from the sapphire substrate 11 side with respect to the optical filter 30. The solid line corresponds to an incident angle of 0 °, and the dotted line corresponds to an incident angle of 30 °. Note that the reflectance of the antireflection film 14 formed on the first main surface of the sapphire substrate 11 is assumed to be zero, and its influence is ignored.

  Here, CuO-containing fluorophosphate glass is used as the absorbing glass 12c, and the CuO concentration is adjusted so that the transmittance at a wavelength of 850 nm at which absorption is maximum in the near-infrared wavelength region is approximately 25%. Moreover, the near-infrared absorption layer 12b containing the near-infrared absorber which illustrates a spectral transmittance in FIG. 5A, and the near-ultraviolet absorption layer 12a which contains the near-ultraviolet absorber which illustrates a spectral transmittance in FIG. 5B are used. ing. The spectral transmittance of the entire absorbing layer composed of the near-ultraviolet absorbing layer 12a, the near-infrared absorbing layer 12b, and the near-infrared absorbing glass 12c corresponds to the product of the spectral transmittance of FIG. 5C and the near-infrared absorbing glass 12c.

  8 and 10, the optical filter 30 has a spectral transmittance curve closer to the visual sensitivity, although the transmittance in the wavelength range of 570 to 680 nm is lower than that of the optical filter 10. An optical filter with little change in spectral transmittance at an angle of 0 to 30 ° is obtained.

[Imaging device and portable device]
An imaging apparatus and a portable device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a cross-sectional view (partially enlarged view) schematically showing a portion where the imaging device 110 is mounted in the portable device 100 according to the embodiment. The portable device 100 houses an imaging device 110 inside a casing 27 of the portable device. The imaging device 110 includes a solid-state imaging element 21, an imaging lens 23, and a housing of the imaging device that houses them. The solid-state image sensor 21 and the imaging lens 23 are provided with a body 24, a lens unit 25 that is provided inside the housing 24 of the imaging device, and fixes the imaging lens 23 in a predetermined position, and the optical filter 10. Arranged along the axis X. The optical filter 10 is fixed as a cover glass to the casing 27 of the portable device.

The difference from the conventional portable device 200 shown in FIG. 15 is that the optical filter 22 incorporated in the imaging device 210 is secured as the optical filter 10 integrated with the cover glass in the portable device 100 of the present embodiment. However, it is fixed to the casing 27 of the portable device 100 outside the imaging device 110. As a result, the distance between the lens unit 25 to which the imaging lens 23 of the imaging device 110 is fixed and the solid-state imaging device 21 can be shortened, and the imaging device 110 can be reduced in size and height. Further, since the optical filter function is imparted to the cover glass in which the impact resistance is ensured, it is possible to avoid a decrease in the impact resistance accompanying the reduction in the thickness of the conventional optical filter 22.
At this time, the optical filter 10 is provided in the opening of the housing 27, but it may be provided so that the surfaces of the housing 27 and the optical filter 10 are aligned, or fixed to the opening on the inside or outside of the housing 27. Alternatively, it is preferably provided in the opening on the outside of the housing 27. At this time, the transparent substrate constituting the optical filter 10 functions as a protective member used in the portable device in addition to the function of the support member that supports the absorption layer and the reflection layer.

  Here, the portable device including the imaging device 110 is not particularly limited, and can be applied to a known portable device. Examples of the portable device include wearable devices such as a digital still camera, a digital video camera, a mobile phone, a smartphone, a mobile personal computer, and a head mounted display.

  The optical filter of the present invention will be described below based on examples showing specific configuration examples and characteristic examples.

Example 1
The optical filter 10 having the configuration shown in FIG. 1A is manufactured as follows.
As the transparent substrate 11, sapphire having a thickness of 0.3 mm having high strength and wear resistance, less scratches and cracks compared to ordinary glass, and having stable optical characteristics is used.

The refractive index n _{d of} sapphire is 1.768 (wavelength 588 nm) is larger than that of ordinary white glass, and the Fresnel reflection loss at the air interface is as large as 7.7%. Further, Ta ₂ O ₅ with n _H = 2.14 as a high refractive index transparent dielectric film and SiO ₂ with n _L = 1.46 as a low refractive index transparent dielectric film are alternately laminated to form an antireflection film 14. Form. Further, a Sn-containing SiO ₂ film having a thickness of 10 nm and a refractive index of 1.51 is formed by sputtering as a surface protective layer (not shown) of the antireflection film. Here, the configuration of the antireflection film 14 is as shown in Table 1.

At this time, in the antireflection film 14, the spectral reflectances with incident angles of 0 °, 30 °, and 45 ° correspond to R (0), R (30), and R (45) in FIG. 3A, and have wavelengths of 420 to 560 nm. Are 1.0%, 0.8%, and 1.1%, respectively, and the average value R _S of the entire incident angle (0 °, 30 °, and 45 °) is 1.0%. On the other hand, 0.3% The average value of the wavelength 570~660nm is from 0.3% 0.8%, an average value _{R L} of the entire incident angle is 0.4%. Therefore, since R _S > R _L , the color temperature of the reflected light of the anti-reflection film 14 is higher than that of white light, and the appearance of the appearance color close to bluish white is exhibited.

Table 6 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the antireflection film 14 using incident light as a CIE standard D65 white light source having a color temperature of 6500K. The chromaticity coordinates (Xn, Yn) at incident angles of 0 °, 30 °, and 45 ° correspond to temperatures higher than the white light source values (0.313, 0.329), and are bluish because b ^* is −4.5 or less. It becomes a hue.

In addition, instead of the Sn-containing SiO ₂ film, a diamond-like carbon (DLC) having a thickness of 3 nm may be formed as the surface protective layer.

  Alternatively, a fluorine-based oil repellent (trade name “OPTOOL DSX” manufactured by Daikin Industries, Ltd.) may be formed on the surface protective layer to form an antifouling coating layer having a thickness of 7 nm.

  Next, the absorption layer 12 is formed on the second main surface of the sapphire transparent substrate 11. Add a silane coupling agent 1- [3- (trimethoxysilyl) propyl] urea to a 15% by mass cyclohexanone solution of polyester resin (trade name: OKP850 OKP850; refractive index 1.64) manufactured by Osaka Gas Chemical Co., Ltd. Let Furthermore, in this resin solution, a near-infrared absorbing dye composed of a squarylium compound and a merocyanine dye as a near-ultraviolet absorber are appropriately adjusted in a range of 0.01 to 20 parts by mass with respect to 100 parts by mass of the resin. After mixing, the mixture is dissolved to prepare a coating solution for forming the absorption layer 12.

  As the squarylium compound and the merocyanine dye, materials described in the following formulas (F11-2) and (M-2) are used.

  This coating solution is applied to the anti-second main surface of the sapphire substrate by spin coating, and heated to form an absorption layer having a thickness of 10 μm. As a result, the near infrared wavelength region of 680 to 750 nm and the near ultraviolet wavelength region of 360 to 400 nm can be blocked by absorption of the absorption layer 12.

  The Fresnel reflection generated at the interface between the sapphire substrate and the polyester resin has a refractive index difference as small as about 0.1, and is 0.2% or less, and is not visually recognized as a reflected color.

Thereafter, the reflective layer 13 exemplified in the above-described embodiment is formed on the surface of the absorption layer 12 by vacuum deposition. Specifically, the high refractive index _n H = 2.25 TiO ₂ film and the multilayer film structure 49 layers shown in Table 3 obtained by stacking SiO ₂ films alternately having a low refractive index _n L = 1.45 at a wavelength of 840nm It is said.

  The spectral transmittance of the optical filter 10 obtained in this manner is calculated in consideration of the spectral transmittance of the antireflection film 14 in FIG. 8 showing the spectral transmittance of the absorption layer 12 and the reflective layer 13 as a whole. Since the reflectance of the antireflection film 14 in the visible range of 400 to 700 nm is 2% or less with respect to an incident angle of 0 to 45 °, the spectral transmittance of the optical filter 10 corresponds to FIG.

  FIG. 9 shows a result of calculating the spectral reflectance of the optical filter 10 with respect to incident light from the sapphire substrate 11 side in consideration of the influence of the spectral reflectance of the antireflection film 14. Specifically, the spectral reflectance of the entire optical filter 10 based on the reflectance of the antireflection film 14, the reflectance of the interface between the sapphire substrate 11 and the absorbing layer 12, the transmittance of the absorbing layer 12, and the reflectance of the reflecting layer 13. Was calculated.

In the optical filter 10 obtained as described above, the average values of wavelengths 420 to 560 nm are 2.3%, 2.2%, and 8. The average value R _S of the entire incident angle (0 °, 30 °, 45 °) is 4.3%. On the other hand, 0.9% average wavelength 570~660nm respectively, 1.1%, becomes 7.8%, an average value _{R L} of the entire incidence angle is 3.3%. Therefore, since R _S > R _L , the color temperature of the reflected light of the optical filter 10 is higher than that of white light, and the design of an appearance color close to bluish white is exhibited.

Table 7 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the optical filter 10 using incident light as a CIE standard D65 white light source with a color temperature of 6500K. Chromaticity coordinates (Xn, Yn) at incident angles of 0 °, 30 °, and 45 ° correspond to temperatures higher than the white light source values (0.313, 0.329), and are bluish because b ^* is −11.4 or less. It becomes a hue.

(Example 2)
The optical filter 20 shown in FIG. 1B is manufactured as follows.
Here, near-infrared light having a CuO concentration adjusted so that the minimum transmittance in the near-infrared wavelength region of 850 to 950 nm with a thickness of 0.2 mm is approximately 25% using a fluorophosphate glass added with CuO. Absorption type glass 12c is used.

  Other configurations such as the antireflection film 14, the absorption layer 12, and the reflection layer 13 are the same as those of the optical filter 10 according to the first embodiment, and thus description thereof is omitted.

  In the optical filter 20, the reflective layer 13 is formed on the air interface side of the near-infrared absorbing glass 12c, and the absorbing layer 12 functions as an adhesive between the transparent substrate 11 made of sapphire and the near-infrared absorbing glass 12c.

  The spectral transmittance of the optical filter 20 obtained in this way is the influence of the spectral transmittance of the antireflection film 14 in FIG. 10, which shows the spectral transmittance of the absorption layer 12, the near-infrared absorbing glass 12 c and the reflective layer 13 as a whole. It is calculated considering Since the reflectance of the antireflection film 14 in the visible range of 400 to 700 nm is 2% or less with respect to an incident angle of 0 to 45 °, the spectral transmittance of the optical filter 20 corresponds to FIG.

  FIG. 11 shows a result of calculating the spectral reflectance of the optical filter 20 with respect to incident light from the sapphire substrate 11 side in consideration of the spectral reflectance of the antireflection film 14.

  Compared with the spectral reflectance of the optical filter 10 shown in FIG. 9, the reflectance of 620 to 670 nm at an incident angle of 45 ° is reduced by the influence of the absorption of the near-infrared absorbing glass 12 c, and the reflected light of 420 to 510 nm is relatively less. The ratio increases.

The reflectances of the optical filter 20 with incident angles of 0 °, 30 °, and 45 ° are 2.3%, 2.2%, and 8.5% of average values of wavelengths of 420 to 560 nm, respectively. The average value R _S of 0 °, 30 °, 45 °) is 4.3%. On the other hand, 0.7% average wavelength 570~660nm respectively, 0.8%, becomes 4.7%, an average value _{R L} of the entire incident angle is 2.1%. Therefore, since R _S > R _L , the color temperature of the reflected light of the optical filter 20 is higher than that of white light, and the design of an appearance color close to bluish white is exhibited.

Table 8 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the optical filter 10 using incident light as a CIE standard D65 white light source with a color temperature of 6500K. The chromaticity coordinates (Xn, Yn) at the incident angles of 0 °, 30 °, and 45 ° of the optical filter 20 correspond to higher temperatures than the white light source values (0.313, 0.329), and b ^* is −12.2. It becomes a pale shade for the following.

(Example 3)
The optical filter 30 shown in FIG. 1C is manufactured as follows.

  A near-ultraviolet absorbing layer 12a made of a transparent resin containing a near-ultraviolet absorber and a near-infrared absorbing layer 12b made of a transparent resin containing a near-infrared absorber are separately formed on both sides of the near-infrared absorbing glass 12c. It is configured as an absorption layer.

  A coating solution made of a resin solution containing only a near-infrared absorbing dye made of a squarylium compound is prepared, applied to one side of the near-infrared absorbing glass 12c by a spin coating method, and heated to absorb near-infrared having a thickness of 10 μm. Layer 12b is formed. The resin solution uses the same material as in Example 1, and the concentration of the near-infrared absorbing agent is adjusted so that the near-infrared absorbing layer 12b has the spectral transmittance shown in FIG. 5A.

Next, the near ultraviolet absorption layer 12a made of a transparent resin containing a near ultraviolet absorber is formed on the second main surface of the sapphire transparent substrate 11 having the antireflection film 14 formed on the first main surface.
Since the near-ultraviolet absorbing layer 12a also functions as an adhesive between the near-infrared absorbing glass 12c and the sapphire transparent substrate 11, an ultraviolet curable resin containing the same merocyanine dye as in Example 1 is used as the near-ultraviolet absorber. After applying a radical polymerization type curable compound (monomer) before curing containing a near ultraviolet absorber at a uniform concentration on the second main surface of the sapphire transparent substrate 11, the near infrared ray of the near infrared absorbing glass 12c is applied. It joins with the main surface in which the absorption layer 12b is not formed. Furthermore, by irradiating ultraviolet rays from the first main surface side of the sapphire transparent substrate 11 to polymerize and solidify the curable compound, the near-infrared absorbing glass 12c becomes the optical filter 30 integrated with the sapphire transparent substrate 11. .

  A polymerizable compound having an epoxy group is used as the radical polymerization type curable resin, and 0.1% by mass to 2% by mass of a photopolymerization initiator is contained with respect to the total amount. The film thickness of the near ultraviolet absorbing layer 12a is preferably 1 to 20 μm, and more preferably 2 to 10 μm. The other components such as the absorbent used for the near ultraviolet absorbing layer 12a and the near infrared absorbing layer 12b, the antireflection film 14, the near infrared absorbing glass 12c, and the reflecting layer 13 are the same as those of the optical filter 20 of the second embodiment. Description is omitted.

  The spectral transmittance and spectral reflectance of the optical filter 30 with respect to incident light from the sapphire substrate 11 side are substantially the same as those in the second embodiment. Since the near-ultraviolet absorbing layer 12a and the near-infrared absorbing layer 12b are formed separately, the options of the resin used for the absorbing layer 12a that also functions as an adhesive are expanded, so that the characteristics are easily improved.

Example 4
In the optical filter 10 of Example 1, acryloyl morpholine and tricyclodecane dimethanol diacrylate were further contained as a green coloring material in the absorption layer made of a transparent resin containing a near ultraviolet absorber and a near infrared absorber. An optical filter is manufactured.

  The content of the green colorant is the content of the green colorant so that the difference between the maximum value and the minimum value of the transmittance in the visible region of 420 to 660 nm is about 10% in the transparent resin containing only the green colorant. The amount has been adjusted.

  Furthermore, the film thickness of the multilayer film is adjusted so that the reflectance at the incident angles of 0 ° and 30 ° in the visible range of 420 to 660 nm of the reflective layer 13 is approximately 10%. Further, the antireflection film 14 is adjusted so that the residual reflection at an incident angle of 0 ° in the visible range of 420 to 660 nm is 0.5% or less. Since other configurations are the same as those of the optical filter 10 of the first embodiment, description thereof is omitted.

  FIG. 12A and FIG. 12B show the calculation results of the spectral transmittance and spectral reflectance of the optical filter 10 in the wavelength range of 400 to 700 nm with respect to the incident light from the sapphire substrate 11 side. The incident angles of 0 °, 30 °, and 45 ° are indicated by solid lines, dotted lines, and alternate long and short dash lines.

Table 9 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the optical filter 10 using incident light as a CIE standard D65 white light source with a color temperature of 6500K. The chromaticity coordinates (Xn, Yn) at incident angles of 0 °, 30 °, and 45 ° have smaller Xn values and larger Yn values than the white light source values (0.313, 0.329). In addition, since a ^* is −15.8 or less, the color becomes green to blue-green. That is, it is possible to adjust the reflection color unique to the material by including the coloring material in the transparent resin.

(Example 5)
The optical filter 40 shown in FIG. 1D is manufactured as follows.
An antireflection film 15 having the configuration shown in Table 4 is formed on the second main surface of the transparent substrate 11 made of sapphire. At this time, in the antireflection film 15, the spectral reflectances with incident angles of 0 °, 30 °, and 45 ° correspond to R (0), R (30), and R (45) in FIG. 4A and have wavelengths of 420 to 560 nm. Are 1.3%, 0.6%, and 0.2%, respectively, and the average value _RS of the entire incident angle (0 °, 30 °, and 45 °) is 0.7%. On the other hand, 0.1% respectively, the mean value of the wavelength 570~660nm, 0.0%, 0.2%, an average value _{R L} of the entire incident angle is 0.1%. Therefore, since R _S > R _L , the color temperature of the reflected light of the anti-reflection film 15 is higher than that of white light, and the appearance of the appearance color close to bluish white is exhibited.
Since other structures such as the absorption layer 12a and the absorption layer 12b, the antireflection film 14, the absorption glass 12c, and the reflection layer 13 are the same as those of the optical filter 30 of the third embodiment, description thereof is omitted.

  FIG. 13 shows the calculation result of the spectral reflectance in the wavelength range of 400 to 700 nm of the optical filter 40 with respect to the incident light from the transparent substrate 11 side made of sapphire. The incident angles of 0 °, 30 °, and 45 ° are indicated by solid lines, dotted lines, and alternate long and short dash lines.

In the optical filter 40 obtained as described above, the average values of wavelengths 420 to 560 nm are 3.6%, 2.7%, and 8. The average value _RS of the entire incident angle (0 °, 30 °, 45 °) is 5.0%. On the other hand, 0.8% average wavelength 570~660nm respectively, 0.9%, becomes 4.9%, an average value _{R L} of the entire incidence angle is 2.2%. Therefore, since R _S > R _L , the color temperature of the reflected light of the optical filter 40 is higher than that of white light, and the appearance of the appearance color close to bluish white is exhibited.

Table 10 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the optical filter 10 using incident light as a CIE standard D65 white light source having a color temperature of 6500K. Chromaticity coordinates (Xn, Yn) at incident angles of 0 °, 30 °, and 45 ° correspond to temperatures higher than the white light source values (0.313, 0.329), and are blue because b ^* is −19.6 or less. It becomes a hue.

(Comparative example)
A configuration in which the order of the absorption layer 12 and the reflection layer 13 formed on the second main surface of the transparent substrate 11 made of sapphire is reversed with respect to the optical filter 10 shown in FIG. 1A will be considered below. This configuration corresponds to an optical filter 22B in which an optical filter 22A is integrated with a conventional cover glass, as illustrated in FIGS. 16A and 16B.

  That is, the reflective layer 13 is formed on the second main surface of the transparent substrate 11 on which the antireflection film 14 is formed on the first main surface, and the absorption layer 12 is further formed on the reflective layer 13. . An antireflection film may be formed to reduce the Fresnel reflection of about 6% generated at the air interface of the absorption layer 12. Other configurations such as the absorption layer 12, the reflective layer 13, and the antireflection film 14 are the same as those of the optical filter 10 of Example 1 except that the stacking order is different, and thus the description thereof is omitted.

  FIG. 14 shows the calculation result of the spectral reflectance in the wavelength range of 400 to 700 nm of the optical filter 10 with respect to the incident light from the transparent substrate 11 side. The incident angles of 0 °, 30 °, and 45 ° are indicated by solid lines, dotted lines, and alternate long and short dash lines.

In the optical filter described above, the reflectances at incident angles of 0 °, 30 °, and 45 ° are 3.7%, 3.6%, and 15.2%, respectively, with average values of wavelengths of 420 to 560 nm. The average value _RS of (0 °, 30 °, 45 °) is 7.5%. On the other hand, 2.1% average wavelength 570~660nm respectively, 2.5%, becomes 26.7 percent, average _{R L} of the entire incidence angle is 10.4%. Therefore, since R _S > R _L , the color temperature of the reflected light of the optical filter is lower than that of white light, and the design of an appearance color close to reddish white is exhibited.

  In the configuration of the optical filter of the comparative example, the reflected light of the reflective layer 13 is emitted from the incident light side without being absorbed by the absorption layer 12, and as the incident angle increases from 0 ° to 30 ° and 45 °, Since reflected light in the near-infrared wavelength region shifts to the visible wavelength region side, red reflected light increases.

Table 11 shows the results of calculating the CIE chromaticity coordinates and the L ^* a ^* b ^* color system chromaticity number from the spectral reflectance of the optical filter 10 using incident light as a CIE standard D65 white light source with a color temperature of 6500K. The chromaticity coordinates (Xn, Yn) at the incident angles of 0 °, 30 °, and 45 ° have smaller Yn values than the white light source values (0.313, 0.329). Further, since the average values of a ^* and b ^* are 23.1 and -20.9, it corresponds to the hue of blue-red, the red reflection color becomes stronger with the increase of the incident angle, and the visually recognized hue is an example. Different from 1-5. The spectral transmittance is substantially the same as that of the optical filter 10 of the first embodiment.

  As described above, the optical filter having the configuration of the present embodiment can maintain its optical characteristics and adjust the color while ensuring its strength.

  The optical filter of the present invention is useful as an optical filter used in an imaging apparatus such as a digital still camera, a digital video camera, and a mobile phone camera using a solid-state imaging device (CCD, CMOS, etc.). In particular, it is useful to use the optical filter of the present invention for a small imaging device mounted on a portable device.

10, 20, 30, 40: Optical filter 11: Transparent substrate 12: Absorbing layer 12a: Near-ultraviolet absorbing layer 12b made of transparent resin containing near-ultraviolet absorber: Near-infrared made of transparent resin containing near-infrared absorber Absorbing layer 12c: Near-infrared absorbing glass 13: Reflecting layer 14: Antireflective film 15: Antireflective film or dielectric film 16: Adhesive layer 21: Solid-state imaging device 22: Optical filter 23: Imaging lens 24: Housing of imaging device Body 25: Lens unit 26: Cover glass 27: Case 100, 200 of mobile device: Mobile device 110, 210: Imaging device

Claims (16)

A transparent substrate having a first main surface and a second main surface opposite to the first main surface and transmitting light in the visible range;
An absorption layer provided on the second main surface and having a near-infrared absorbing ability to absorb at least light in the near-infrared region;
A reflective layer that is laminated on the absorption layer, transmits visible light, and reflects near-ultraviolet and near-infrared light;
An optical filter comprising:
The thickness of the transparent substrate is 0.2 to 0.5 mm, and the surface strength of at least one principal surface of the first principal surface and the second principal surface is 170 N or more. filter. A first antireflection film provided on the first main surface and preventing reflection of light in the visible range;
Wherein the optical filter, the spectral reflectance of incident light from the first anti-reflection film side, the incident angle 0 to 45 °, the average value _{R S} wavelength 420~560nm is, the incidence angle 0 to 45 °, wavelength 570 The optical filter according to claim 1, which is larger than an average value R _{L of} ˜660 nm.   The optical filter according to claim 1, wherein the absorption layer is made of a transparent resin containing a near-infrared absorber and transmitting visible light.   The optical filter according to claim 3, wherein the absorption layer further contains a near ultraviolet absorber.   The absorption layer contains a near-infrared absorber, a transparent resin that transmits visible light, and a near-infrared absorbing glass that absorbs near-infrared light and transmits visible light. The optical filter according to claim 1 or 2.   The absorption layer absorbs near-infrared light from a near-ultraviolet-absorbing layer composed of a transparent resin that contains a near-ultraviolet absorber and transmits visible light from the second main surface. The optical according to claim 1 or 2, wherein a near-infrared absorbing glass that transmits light and a near-infrared absorbing layer that includes a near-infrared absorber and is made of a transparent resin that transmits visible light. filter.   The optical filter according to claim 6, wherein the near-ultraviolet absorbing layer contains a color absorbent that absorbs light in a predetermined wavelength range in the visible range. The reflective layer has a multilayer film structure in which a high-refractive index dielectric film and a low-refractive index dielectric film are stacked, and a spectral reflectance average value R _S with an incident angle of 0 to 45 ° and a wavelength of 420 to 560 nm is incident. The optical filter according to any one of claims 1 to 7, wherein the optical filter has an angle of 0 to 45 ° and a spectral reflectance average value _RL having a wavelength of 570 to 660 nm.   The optical filter according to claim 1, further comprising a second antireflection film between the transparent substrate and the absorption layer. The first anti-reflection film or the second antireflection film, the spectral reflectance, the incident angle 0 to 45 °, the average value _{R S} wavelength 420~560nm is, the incidence angle 0 to 45 °, wavelength 570 to The optical filter according to claim 2, wherein the optical filter is larger than an average value R _{L of} 660 nm. The refractive index n _G of the transparent substrate has a value larger than the refractive index n _C of the near-ultraviolet absorbing layer, and the refractive index of the second antireflection film is in the range of the refractive indexes n _{G to} n _C. The optical filter according to claim 9, wherein the optical filter is a single-layer dielectric film.   The optical filter according to claim 1, wherein the reflective layer is provided on the absorption layer.   An imaging apparatus comprising the optical filter according to claim 1. An imaging device according to claim 13,
While fixing the optical filter of the imaging device, a housing for a portable device that houses the imaging device inside,
A portable device characterized by comprising:   The portable device according to claim 14, wherein the optical filter is fixed to an opening on the outside of the housing.   The portable device according to claim 14 or 15, wherein the transparent substrate also serves as a protective member used for the portable device and a support member that supports the absorbing layer and the reflective layer.

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