JP2017146506A - Optical filter and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical filter including an absorption layer in which temperature dependency of an optical characteristic is suppressed.SOLUTION: The optical filter includes an absorption layer comprising a first absorber and a second absorber having absorption wavelength regions which are at least partially overlap in a wavelength range from 350 to 1200 nm. The first absorber and the second absorber have a first transition wavelength region and a second transition wavelength region, respectively, where transition from a transmission wavelength region to a cutoff wavelength region appears. The first absorber shows a shift toward a shorter wavelength side of a spectral transmittance curve in the first transition wavelength region with elevation of temperature; and the second absorber shows a shift toward a longer wavelength side of a spectral transmittance curve in the second transition wavelength region with elevation of temperature.SELECTED DRAWING: None

Description

  The present invention relates to an optical filter that transmits visible light and blocks near-infrared light, and an imaging device using the optical filter.

  In an imaging apparatus using a solid-state imaging device, an optical filter that transmits visible light and blocks near-infrared light is used in order to reproduce color tone well and obtain a clear image. As the optical filter, a near-infrared cut filter comprising an absorption layer containing a near-infrared absorbing dye and a reflective layer made of a dielectric multilayer film that blocks ultraviolet light and near-infrared light is known (patent) References 1-4). Since the spectral transmittance curve of a dielectric multilayer film changes depending on the incident angle, the near-infrared cut filter including both the reflective layer and the absorbing layer has a spectral transmittance curve whose dependence on the incident angle is suppressed by the absorption characteristics of the absorbing layer. Is obtained.

JP 2013-190553 A JP 2014-52482 A International Publication No. 2014/002864 Korean Registered Patent No. 1453469

Until now, such near-infrared cut filters have not been specifically studied with respect to the optical characteristics with respect to ambient temperature changes, in particular, the temperature dependence of the spectral transmittance curve that affects color reproducibility. For this reason, the near-infrared cut filter whose optical characteristics greatly change depending on the temperature may not sufficiently suppress deterioration in color reproducibility due to, for example, the incident angle dependency of the reflective layer.
Therefore, an object of the present invention is to provide an optical filter in which the temperature dependence of optical characteristics is suppressed, and an imaging device using the optical filter.

  The optical filter which concerns on 1 aspect of this invention is equipped with the absorption layer containing the 1st absorber and the 2nd absorber which have the absorption wavelength range which overlaps with wavelength 350-1200 nm at least partially, Said 1st absorber And each of the second absorbers has a first transition wavelength region and a second transition wavelength region that transition from a transmission wavelength region to a cut-off wavelength region, and the first absorber has an increase in temperature. The spectral transmittance curve in the first transition wavelength region is shifted to the short wavelength side, and the second absorber shifts the spectral transmittance curve in the second transition wavelength region to the long wavelength side as the temperature rises. It is characterized by doing.

  According to the present invention, it is possible to obtain an optical filter that suppresses temperature dependency of optical characteristics, suppresses deterioration of color reproducibility with respect to a temperature change, and an imaging apparatus using the optical filter.

It is sectional drawing which shows the example of the optical filter of one Embodiment roughly. It is a figure which shows the spectral transmittance curve of the reflection layer used for the optical filter of the Example. (A) is the spectral transmittance curve measured at 30 degreeC and 100 degreeC about the optical filter of an Example, (b) is a figure which shows the spectral transmittance curve measured at normal temperature about the same optical filter. It is a figure which shows the spectral transmittance curve of each pigment | dye of the absorption layer in one Example. It is a figure which shows the spectral transmittance curve of each pigment | dye of the absorption layer in one Example. It is a figure which shows the spectral transmittance curve of each pigment | dye of the absorption layer in one Example. It is a figure which shows the spectral transmittance curve of each pigment | dye of the absorption layer in one Example.

  The optical filter according to the present invention has an absorption layer including a first absorber and a second absorber having an absorption wavelength region that at least partially overlaps a wavelength of 350 to 1200 nm. Each of the first absorber and the second absorber has a first transition wavelength region and a second transition wavelength region that transition from a transmission wavelength region to a cutoff wavelength region. Hereinafter, each embodiment will be described in detail.

(First embodiment)
In the optical filter of the present embodiment (hereinafter also referred to as “the present filter” in the description of the first embodiment), both the first absorber and the second absorber have wavelengths from 540 to 790 nm, and from the transmission wavelength range. It is a near-infrared cut filter containing an absorbent having a (first and second) transition wavelength range that transitions to a cutoff wavelength range.

A typical example of the absorbent used as the first and second absorbers is a dye (near infrared absorbing dye), but is not limited thereto. In addition, the first and second absorbers are near-infrared absorbing particles, such as compound A _{1 / n} CuPO ₄ (where A is one or more selected from the group consisting of alkali metals, alkaline earth metals, and NH _4). And n is 1 or 2.), and specifically includes a crystallite of KCuPO ₄ .

  Hereinafter, the first and second absorbers will be described as (near infrared absorption) dyes. Moreover, the pigment | dye which comprises a 1st absorber is called 1st pigment | dye, and the transition wavelength range in this 1st pigment | dye is called 1st transition wavelength region. And the pigment | dye which comprises a 2nd absorber is called a 2nd pigment | dye, and the transition wavelength range in this 2nd pigment | dye is called a 2nd transition wavelength range. The “(first and second) transition wavelength region” means that the first and second absorbers exhibit maximum transmittance from the wavelength exhibiting the minimum transmittance to the short wavelength side at wavelengths of 540 to 790 nm, respectively. It is defined as the wavelength range until the transition to the wavelength. For example, when these pigments are dyes, the first and second transition wavelength regions may be determined based on the above definition in a spectral transmittance curve measured in a state dissolved in dichloromethane or a specific transparent resin.

  The first and second absorbers may have a minimum transmittance of 20% or less at a wavelength of 540 to 790 nm, preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. The first and second absorbers may have a maximum transmittance at a wavelength of 540 to 790 nm of 60% or more, preferably 70% or more, more preferably 80% or more, and 90% or more. More preferred. Further, unless otherwise specified, the first and second transition wavelength regions are defined based on a spectral transmittance curve at room temperature (range of 20 ° C. ± 15 ° C.).

  Here, let the 1st pigment | dye be the object which shows the characteristic which shifts the spectral transmittance curve in a 1st transition wavelength area to the short wavelength side with a raise in temperature. The second dye is a target that exhibits the characteristic of shifting the spectral transmittance curve in the second transition wavelength region to the longer wavelength side as the temperature rises. Hereinafter, the shift to the long wavelength side of the spectral transmittance curve according to the temperature rise is also referred to as “positive shift”, and the shift to the short wavelength side is also referred to as “negative shift”.

  The absorption layer containing the first and second dyes may be one layer or two or more layers, and the absorption layer only needs to include at least the first dye and the second dye in the thickness direction. When two or more layers are provided, each layer may have the same configuration or a different configuration. When the absorption layer has two layers, a combination of a layer made of a resin containing the first dye and a layer made of a resin containing the second dye may be used. Further, the absorbing layer may include an absorber other than the first and second dyes (hereinafter referred to as a third absorber). The third absorber is an absorber in which the first and second pigments do not have a transition wavelength region in the specific wavelength region in which the (first and second) transition wavelength regions are present. Can be mentioned. Two or more types of the first dye, the second dye, and the third absorber may be included in the absorption layer. Furthermore, the absorption layer itself may include a substrate, such as a near-infrared absorbing glass substrate or a near-infrared absorbing resin substrate.

  The filter may further include a reflective layer. The reflective layer has one or more dielectric multilayer films. The dielectric multilayer film is not limited to being composed of a dielectric film, but may include a material other than a dielectric (for example, a metal film) in part. When the reflective layer has two or more dielectric multilayer films, the reflective layer is usually composed of a plurality of dielectric multilayer films having different reflection bands. For example, one is a near-infrared reflective layer that reflects light on the short wavelength side in the near-infrared region (700 to 1150 nm), and the other is both the long-wavelength side and near-ultraviolet regions in the near-infrared region. The structure used as the near-infrared / near-ultraviolet reflective layer which reflects light is mentioned.

  The filter may further have a transparent substrate. When this filter has a transparent substrate, an absorption layer, and a reflection layer, the absorption layer and the reflection layer may be provided on the same main surface of the transparent substrate, or may be provided on different main surfaces. When the absorption layer and the reflection layer are provided on the same main surface, the stacking order is not limited.

  The filter may also have other functional layers such as an antireflection layer that suppresses visible light transmittance loss. In particular, it is preferable to provide an antireflection layer on the absorption layer so that the absorption layer of the present filter does not come into contact with air, in that the light utilization efficiency can be improved. The antireflection layer may be configured to cover the entire side surface in addition to the main surface of the absorption layer. In this case, the moisture-proof effect of the absorption layer can be enhanced.

  Next, FIG. 1 shows a configuration example of this filter. 1A is an optical filter including only the absorption layer 11, and FIG. 1B is an optical filter 20 including the reflective layer 12 on one main surface of the absorption layer 11. The phrase “having another layer such as the reflective layer 12 on one main surface of the absorption layer 11” is not limited to the case where another layer is provided in contact with the absorption layer 11, and the absorption layer 11 and the other The case where another functional layer (including a space) is provided between these layers is also included, and the following configurations are also the same. Here, the absorption layer 11 in the optical filters 10 and 20 may have the function of a transparent substrate.

  FIG. 1C shows an optical filter 30 having an absorption layer 11 on one main surface of the transparent substrate 13 and a reflection layer 12 on the other main surface. FIG. 1 (d) shows an optical filter 40 that includes an absorption layer 11 and an antireflection layer 14 in this order on one main surface of the transparent substrate 13, and a reflection layer 12 on the other main surface. Next, the absorption layer, the reflective layer, the transparent substrate and the antireflection layer of this filter will be described in detail.

<Absorption layer>
The absorption layer contains a first dye (hereinafter referred to as “Dye A1”), a second dye (hereinafter referred to as “Dye A2”), and a transparent resin B, and is typically transparent. This is a layer in which the dye A1 and the dye A2 are uniformly dissolved or dispersed in the resin B at a predetermined weight ratio. The absorption layer may contain a dye other than the dye A1 and the dye A2, that is, a third dye (hereinafter referred to as “dye A3”).

  The dye A1 is a dye that has a first transition wavelength region at a wavelength of 540 to 790 nm in the absorption layer and negatively shifts the spectral transmittance curve in the first transition wavelength region. The dye A2 is a dye that has a second transition wavelength region at a wavelength of 540 to 790 nm in the absorption layer and positively shifts the spectral transmittance curve in the second transition wavelength region. The “transition wavelength range” of the absorption layer containing the dye A1 and the dye A2 has a wavelength range that transitions from the transmission wavelength range of the absorption layer to the cut-off wavelength range. Specifically, at the wavelength of 540 to 790 nm, the minimum transmission It is defined as a wavelength region from the wavelength indicating the rate to the wavelength indicating the maximum transmittance on the short wavelength side.

  The types of the pigments A1 and A2 are not particularly limited as long as the above requirements are satisfied. That is, whether the dye exhibits a negative shift behavior or a positive shift behavior depends on the type and addition amount of the dye and the type of the transparent resin B in which the dye is dispersed or dissolved. Accordingly, the dyes A1 and A2 are selected from, for example, squarylium compounds, cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, dithiol metal complex compounds, diimonium compounds, and the like, depending on the transparent resin B that disperses or dissolves them. It is good to select suitably and to combine after adjusting the addition amount.

  The transparent resin B is, for example, in a polyimide resin, a polyester resin, an acrylic resin, or a cyclic olefin resin, and the dye exhibiting a negative shifting behavior used as the dye A1 includes, for example, benzene rings on the left and right sides of the squarylium skeleton. Examples thereof include a squarylium compound having a structure in which a nitrogen atom is bonded to the 4-position of the benzene ring. More specifically, squarylium compounds (including their resonance structures) represented by formulas (A1-11) to (A1-14) can be given. In this specification, unless otherwise specified, a compound represented by the formula (A1-11) is referred to as a compound (A1-11), and a compound represented by another formula is also described in the same manner.

Symbols in the formulas (A1-11) to (A1-14) are as follows.
R ²⁴ and R ²⁶ are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl or alkoxy group having 1 to 6 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, or —NR ²⁷ R ²⁸ (R ²⁷ And R ²⁸ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, —C (═O) —R ²⁹ (R ²⁹ is a hydrogen atom, or a carbon number optionally having a substituent). An alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 11 carbon atoms, or an aryl group having 7 to 18 carbon atoms which may have a substituent and may have an oxygen atom between carbon atoms), -NHR ³⁰ or _-SO 2 ^{-R 30 (R} 30, are each one or more hydrogen atoms are halogen atom, a hydroxyl group, a carboxyl group, may be substituted by a sulfo group or a cyano group, between carbon atoms Unsaturated bond, an oxygen atom, a.) For a hydrocarbon group) saturated or may 1 to 25 carbon atoms which contain an unsaturated ring structure shown.

X ¹ and X ² are each a group represented by the formula (1x) or (2x), and Y ¹ and Y ² are each a group represented by any one selected from the formulas (1y) to (5y). When X ¹ and X ² are groups represented by the following formula (2x), X ¹ and X ² may be directly bonded to the benzene ring.

In the formula (1x), four Z's are each independently a hydrogen atom, a hydroxyl group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, or -NR ³⁸ R ³⁹ (R ³⁸ and R ³⁹ are each independently Represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms). R ^{31 to} R ³⁶ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R ³⁷ is an alkyl group having 1 to 6 carbon atoms or an alkyl group having 6 to 10 carbon atoms. An aryl group is shown.

R ²¹ and R ²² each independently represent a hydrogen atom, an optionally substituted alkyl group or allyl group having 1 to 6 carbon atoms, or an aryl group or aryl group having 6 to 11 carbon atoms. .
R ²³ and R ²⁵ each independently represent a hydrogen atom, a halogen atom, or an alkyl group or alkoxy group having 1 to 6 carbon atoms.
Q is an alkylene group in which a hydrogen atom is substituted with an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an acyloxy group having 1 to 10 carbon atoms which may have a substituent, Or an alkyleneoxy group is shown.

  Examples of the compounds (A1-11), (A1-12), (A1-13) and (A1-14) include the following.

  Moreover, as the pigment | dye which transparent resin B is in a polyimide resin, a polyester resin, an acrylic resin, or a cyclic olefin resin and shows the behavior which carries out the positive shift as pigment | dye A2, formula (A2-11)-(A2-13), for example ) And phthalocyanine compounds such as FDR-004 and FDR-005 (trade name, manufactured by Yamada Chemical Co., Ltd.).

Symbols in formulas (A2-11) to (A2-13) are as follows.
R ^{1 to} R ¹² each independently represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group having 1 to 15 carbon atoms, or an aryl group having 5 to 20 carbon atoms.
R ¹ and R ² may be connected to each other to form a 5-membered ring, a 6-membered ring, or a 7-membered ring. In that case, hydrogen bonded to the carbocycle may be substituted with an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms.
X ⁻ represents a monovalent anion, n represents the number of X ⁻ , and is 0 or 1.

When n is 0, A1 represents an anionic group represented by any ^one of formulas (a1) to (a6).
When n is 1, ^{A 1} is a halogen atom or,, ^-X-A 2 (X is a single bond, an ether bond (-O-), a sulfonyl bond _(-SO 2 -), an ester bond (-C (= O ) —O—, —O—C (═O) —) or a ureido bond (—NH—C (═O) —NH—), and A ² is an alkyl group having 1 to 20 carbon atoms or 6 to 6 carbon atoms. 30 aryl groups).

式（ａ１）〜（ａ６）中、Ｒ^１０１〜Ｒ^１１４はそれぞれ独立に水素原子、炭素数５〜２０のアリール基、または、置換基を有してもよい炭素数１〜１０のアルキル基を示す。

In formulas (a1) to (a6), R ^{101 to} R ¹¹⁴ each independently represent a hydrogen atom, an aryl group having 5 to 20 carbon atoms, or an alkyl group having 1 to 10 carbon atoms that may have a substituent. Show.

Examples of X in X ⁻ include I, PF ₆ , ClO ₄ ⁻ , anions represented by formulas (X1) and (X2), and the like.

  Specific examples of the compound (A2-11) include compounds represented by the formula (A2-11a) and the like, and specific examples of the compound (A2-13) include formulas (A2-13a) and (A2-13b) Examples thereof include compounds shown respectively.

  In addition to the above-mentioned resins, the transparent resin B is an epoxy resin, an ene / thiol resin, a polycarbonate resin, a polyether resin, a polyarylate resin, a polysulfone resin, a polyethersulfone resin, a polyparaphenylene resin, a polyarylene ether phosphate. Fin oxide resin, polyamideimide resin, polyolefin resin, and the like can be used. Moreover, the transparent resin B may be used individually by 1 type, and 2 or more types may be mixed and used for it.

Table 1 shows the spectral transmittance curves at temperatures of 30 ° C. and 100 ° C. for the absorption layer formed by dispersing or dissolving a predetermined amount of each pigment in 100 parts by mass of various transparent resins. This is the result of calculating the shift amount by _{obtaining the} wavelength at which the transmittance is 20%, λ _{T30 ° C.-20%,} and λ _{T100 ° C.-20%} in the transition wavelength region.
Shift amount (nm) = λ _{T100 ° C.−20%} −λ _{T30 ° C.−20%}
The reason why the wavelength at which the transmittance of the first dye and the second dye is 20% is used as an index is that the wavelength at which the transmittance is 20% is derived from the dye due to temperature change. This is because the fluctuation is large, and the temperature dependency of the spectral transmittance curve can be effectively suppressed by suppressing the temperature dependency of the wavelength at which the transmittance is 20%.

  The dyes used were squarylium compounds represented by formulas (A1-11a) and (A1-14a), cyanine compounds represented by formulas (A2-11a), (A2-13a) and (A2-13b), and FDR-004. And phthalocyanine compounds of FDR-005 (trade name, manufactured by Yamada Chemical Co., Ltd.). Transparent resins include polyimide resin (Mitsubishi Gas Chemical Co., Ltd., trade name Neoprim (registered trademark) C3G30), polyester resin (Osaka Gas Chemical Co., Ltd., trade name B-OKP2), acrylic resin (Mitsubishi). Rayon Co., Ltd., trade name BR-50), and cyclic olefin resin (JSR, trade name, ARTON (registered trademark)) were used. For the measurement of the spectral transmittance curve, an HR2000 high-resolution small fiber optical spectrometer manufactured by Ocean Optics was used.

  As is clear from Table 1, the squarylium compounds represented by the formulas (A1-11a) and (A1-14a) are polyimide resin, polyester resin, acrylic resin, and cyclic olefin resin, and their (first) transition. The spectral transmittance curve in the wavelength region showed a negative shift, that is, the behavior as the dye A1. On the other hand, the cyanine compounds represented by the formulas (A2-11a), (A2-13a), and (A2-13b) are spectral transmittances in the (second) transition wavelength region in polyimide resins, polyester resins, and acrylic resins. The curve showed a positive shift, that is, behavior as dye A2. The phthalocyanine-based compound has a positive shift behavior when FDR-004 is polyimide resin and cyclic olefin resin, and FDR-005 is positive shift when polyimide resin, polyester resin, acrylic resin, and cyclic olefin resin are used. The behavior as A2 was shown.

  In the absorption layer containing the first and second dyes, the first transition wavelength region and the second transition wavelength region may overlap in a band of 50 nm or more. By having such an overlapping band, the temperature dependence of the spectral transmittance curve in the absorption layer is reduced, and stable color reproducibility is easily obtained. That is, when there is an overlapping band of 50 nm or more, the effect of cancellation by the negative shift and the positive shift becomes remarkable, and the effect of reducing the shift amount of the spectral transmittance curve in the absorption layer can be obtained even if the temperature changes. The overlapping band of the first and second transition wavelength regions is preferably 80 nm or more, more preferably 100 nm or more, and further preferably 150 nm or more.

  The overlapping band preferably includes either one of a wavelength at which the transmittance of the dye A1 is 20% and a wavelength at which the transmittance of the dye A2 is 20%. And preferred. In addition, it is more preferable that the overlapping band includes any one of a wavelength at which the transmittance of the dye A1 is 15 to 40% and a wavelength at which the transmittance of the dye A2 is 15 to 40%. More preferably, it is contained. Further, this overlapping band preferably includes a wavelength at which the transmittance of the absorption layer containing the dye A1 and the dye A2 is 20%, and includes a wavelength at which the transmittance is 15 to 40%. And more preferred. In addition, it is preferable that all of the above are satisfied at least in a temperature condition of room temperature to 100 ° C.

Furthermore, the absorption layer containing the first and second absorbers preferably satisfies (i) or (ii), and more preferably satisfies both. In this embodiment, in order to satisfy such conditions, each dye and transparent resin are selected, and the concentration and thickness of each dye may be adjusted.
(I) The first absorber has wavelengths λ1 _{T30 ° C-20%} and λ1 _{T100 ° C-20% at} which the transmittance becomes 20% in the first transition wavelength range measured at 30 ° C and 100 ° C, respectively. Have
The second absorber has wavelengths λ2 _{T30 ° C-20%} and λ2 _{T100 ° C-20%} at which the transmittance is 20% in the second transition wavelength range measured at 30 ° C and 100 ° C, respectively.
| Λ1 _{T30 ° C.−20%} −λ1 _{T100 ° C.−20%} | ≦ 10 nm
| Λ2 _{T30 ° C.-20%} −λ2 _{T100 ° C.-20%} | ≦ 10 nm
Meet the relationship.
In (i), the (maximum) value on the right side of the two inequalities is preferably 5 nm, more preferably 3 nm, and even more preferably 2 nm.

(Ii) having a transition wavelength region that transitions from a transmission wavelength region to a cutoff wavelength region;
In the transition wavelength range measured at 30 ° C. and 100 ° C., the wavelengths λ _{T30 ° C.-20%} and λ _{T100 ° C.-20%} at which the transmittance is 20%, respectively,
The wavelengths [lambda] _{T30 [deg.] C.-20%} and [lambda] _{T100 [deg.] C.-20%} satisfy the following relationship.
| Λ _{T30 ° C.-20%} −λ _{T100 ° C.-20%} | ≦ 5 nm
In (ii), the (maximum) value of the right side of the inequality is preferably 3 nm, more preferably 1.5 nm, still more preferably 1 nm, and particularly preferably substantially 0 nm.
In the absorption layer, the transmittance at the wavelength where the absorption rate is maximum may be 10% or less, preferably 5% or less, and more preferably 3% or less.
In addition, as in (i) and (ii), the wavelength at which the transmittance is 20% is given as an index because the wavelength at which the transmittance is 20% due to a temperature change is likely to vary due to the pigment. This is because suppressing the wavelength fluctuation in the transmittance is important for highly accurate color reproducibility.

<Reflective layer>
The reflective layer preferably has a wavelength selection characteristic that transmits visible light and shields light having a wavelength other than the light shielding region of the absorption layer. In this case, the light shielding region of the reflective layer may include the light shielding region of the absorption layer.

  The reflective layer is composed of a dielectric multilayer film in which a low refractive index dielectric film (low refractive index film) and a high refractive index dielectric film (high refractive index film) are alternately stacked. The dielectric multilayer film exhibits a function of controlling the transmission and shielding of light in a specific wavelength region by utilizing light interference, and the transmission / shielding characteristics depend on the incident angle. In general, the wavelength of light shielded by reflection is shorter for light incident obliquely than for light incident vertically (incidence angle 0 °).

In the present embodiment, the dielectric multilayer film constituting the reflective layer may satisfy (iii-1).
(Iii-1) In the spectral transmittance curve at an incident angle of 0 °, the average transmittance of light having a wavelength of λ _{L to} 1100 nm is 10% or less (where λ _L is the first and second absorbers). It is preferably a wavelength on the long wavelength side of the maximum absorption wavelengths at wavelengths of 540 to 790 nm. The average transmittance of light having a wavelength λ _{L to} 1100 nm is preferably as low as possible, and more preferably 1% or less.

The dielectric multilayer film preferably also satisfies (iii-2) and (iii-3).
(Iii-2) In the spectral transmittance curve with an incident angle of 0 °, the transmittance of light having a wavelength of 430 to 550 nm is 90% or more. The transmittance of light having a wavelength of 430 to 550 nm is more preferably 93% or more, still more preferably 95% or more, and even more preferably 97% or more.
(Iii-3) In each spectral transmittance curve at an incident angle of 0 °, the average transmittance of light having a wavelength λ _{b to} 1100 nm is 1% or less (where λ _b is a wavelength of 630 to 800 nm of the absorption layer) The maximum wavelength at which the transmittance of light becomes 1%). As for the average transmittance | permeability of the light of wavelength (lambda) _b- 1100nm, 0.5% or less is more preferable.

It is more preferable that the dielectric multilayer film constituting the reflective layer further satisfies (iii-4) and (iii-5).
(Iii-4) In the spectral transmittance curve at an incident angle of 30 °, the transmittance of light having a wavelength of 430 to 550 nm is 90% or more. The transmittance of light having a wavelength of 430 to 550 nm is more preferably 93% or more, still more preferably 95% or more, and even more preferably 97% or more.
(Iii-5) In each spectral transmittance curve at an incident angle of 30 °, the average transmittance of light having a wavelength λ _{b to} 1100 nm is 1% or less. As for the transmittance | permeability of the light of wavelength (lambda) _b- 1100nm, 0.5% or less is more preferable.
If the reflective layer satisfies (iii-1), a near-infrared cut filter having a high near-infrared shielding effect can be obtained. Moreover, if (iii-2) and (iii-3) are satisfy | filled, the near-infrared cut off filter with the high transmittance | permeability of the light of wavelength 430-550 nm will be obtained. Furthermore, if (iii-4) and (iii-5) are satisfied, a near-infrared cut filter having high transmittance of light having a wavelength of 430 to 550 nm and excellent oblique incidence characteristics can be obtained.

[Transparent substrate]
The transparent substrate may be a material that exhibits high transmittance with visible light having a wavelength of 420 to 670 nm, and may be a material that absorbs near infrared light or near ultraviolet light. Specific examples include inorganic materials such as birefringent crystals such as glass, quartz, lithium niobate, and sapphire, and organic materials such as resins.

Examples of the glass that can be used for the transparent substrate include soda lime glass, borosilicate glass, alkali-free glass, and quartz glass. Moreover, the absorption type glass etc. which added CuO etc. to the fluorophosphate glass, phosphate glass, etc. which are demonstrated in 2nd Embodiment can also be used. The “phosphate glass” includes silicic acid phosphate glass in which a part of the glass skeleton is composed of SiO ₂ . Examples of resins that can be used for the transparent substrate include polyester resins, polyolefin resins, acrylic resins, urethane resins, vinyl chloride resins, fluororesins, polycarbonate resins, polyvinyl butyral resins, polyvinyl alcohol resins, and polyimide resins.

<Antireflection layer>
The filter may include an antireflection layer that reduces the reflection loss of visible light as another functional layer. In order to obtain an antireflection effect of visible light having a wavelength of 400 to 700 nm, the antireflection layer can be realized by stacking, for example, 3 to 9 dielectric films having different refractive indexes so as to have a thickness of 200 to 400 nm.

(Second Embodiment)
The optical filter of the present embodiment (hereinafter also referred to as “the present filter” in the description of the second embodiment) uses an absorptive glass as a part of the absorption layer. For example, the absorption layer of this filter is composed of an absorption type glass in which CuO or the like is added to fluorophosphate glass or phosphate glass, and a layer in which the dye A1 is dissolved or dispersed in the transparent resin B (in this embodiment). And also a “resin layer”).

Absorption type glass in which CuO or the like is added to fluorophosphate glass, phosphate glass, or the like exhibits optical characteristics similar to those of the layer in which dye A2 in the first embodiment is dissolved or dispersed in a transparent resin. That is, it has a second transition wavelength region at a wavelength of 540 to 790 nm, and the spectral transmittance curve in the second transition wavelength region shifts to the long wavelength side, that is, positively shifts as the temperature rises.
Therefore, while the first embodiment includes the dye A2 as the second absorber in the absorption layer, the optical filter of the present embodiment uses absorption glass as the layer including the second absorber. Other configurations are the same as those of the first embodiment. Hereinafter, a description will be given focusing on differences from the first embodiment.

Absorption type glass can adjust the transmittance | permeability of light with a wavelength of 700-1150 nm by adjusting the addition density | concentrations and thickness, such as CuO. Table 2 shows an example of the shift amount of the spectral transmittance curve in the (second) transition wavelength region of the phosphate glass containing CuO and the fluorophosphate glass containing CuO. The amount of shift is determined by measuring each spectral transmittance curve at temperatures of 30 ° C. and 100 ° C. as in the case of the absorption layer formed by dispersing or dissolving the dye described in the first embodiment in various transparent resins. The wavelength λ _{T30 ° C.-20%} and λ _{T 100 ° C.-20% at} which the transmittance of the spectral transmittance curve in the (second) transition wavelength region of the mold glass is _20% are determined, and the shift amount (λ _{T100 ° C.-20%} − ( _{λT30 ° C.−20%} ) (nm) is calculated.

  As apparent from Table 2, the absorption-type glass has a positive shift in its spectral transmittance curve in the (second) transition wavelength region as the temperature increases. Therefore, by combining with a layer containing the dye A1 in which the spectral transmittance curve in the (first) transition wavelength region is negatively shifted as the temperature rises, an optical filter in which the temperature dependence of spectral characteristics is suppressed can be realized. .

When the transparent substrate is a fluorophosphate glass, specifically, P ⁵⁺ 20 to 45%, Al ³⁺ 1 to 25%, R ⁺ 1 to 30% (where R ⁺ is Li ⁺ , It is at least one of Na ⁺ and K ⁺ , and the value on the left is a total value of the respective content ratios), Cu ²⁺ 1 to 20%, R ²⁺ 1 to 50 (provided that R ²⁺ is At least one of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Zn ²⁺ , and the value on the left is the sum of the respective content ratios), and in terms of anion%, ^- 10 to ^65%, preferably contains the O 2-35 to 90%.

Further, when the transparent substrate is a phosphate type glass, represented by _{mass%, P 2 O 5 30~80%,} Al 2 O 3 1~20%, R 2 O 0.5~30%, ( provided that, R ₂ O is at least one of Li ₂ O, Na ₂ O, and K ₂ O, and the values on the left are the total values of the respective content ratios)), CuO 1 to 12%, RO 0.5-40% (however, RO is at least one of MgO, CaO, SrO, BaO, ZnO, and the value on the left is a total value of each content) It is preferable to do.

  Examples of commercially available products include NF-50E, NF-50EX, NF-50T, NF-50TX (made by Asahi Glass Co., Ltd., trade name), BG-60, BG-61 (above, trade name, made by Schott) CD5000 (manufactured by HOYA, trade name) and the like.

The above-described CuO-containing glass may further contain a metal oxide. When the metal oxide contains, for example, one or more of Fe ₂ O ₃ , MoO ₃ , WO ₃ , CeO ₂ , Sb ₂ O ₃ , V ₂ O _5, etc., the CuO-containing glass has ultraviolet absorption characteristics. The content of these metal oxides, relative to the CuO-containing glass 100 parts by _weight, the _{Fe 2 O 3, MoO 3,} WO 3 and at least one selected from the group consisting of CeO _{2, Fe} 2 _{O 3} 0.6-5 parts by mass, MoO ₃ 0.5-5 parts by mass, WO ₃ 1-6 parts by mass, CeO ₂ 2.5-6 parts by mass, or Fe ₂ O ₃ and Sb ₂ O ₃ Fe ₂ O ₃ 0.6 to 5 parts by ₊ Sb ₂ O 3 0.1 to 5 parts by weight, or _V 2 _{O 5} two and CeO _{2 V} 2 _O 5 0.01 to 0.5 parts by + CeO ₂ It is good to set it as 1-6 mass parts.

  Also in this filter, the first transition wavelength region and the second transition wavelength region may have an overlapping band of 50 nm or more, the overlapping band is preferably 80 nm or more, more preferably 100 nm or more, and further 150 nm or more. preferable. Moreover, the absorption layer should just satisfy | fill (i) or (ii) mentioned above, and if both are satisfy | filled, it is preferable. In order to satisfy these conditions, the dye, transparent resin, and absorption glass are selected, the concentration of the dye, the thickness of the layer containing the dye, the concentration of CuO and the like contained in the absorption glass, and the thickness of the absorption glass. Is preferably adjusted.

As described above, this filter has an absorption type glass in which the spectral transmittance curve in the second transition wavelength region is positively shifted with increasing temperature, and the spectral transmittance curve in the first transition wavelength region is negatively shifted with increasing temperature. And an absorption layer including a layer containing the dye A1. Therefore, such an absorption layer as a whole has a transition wavelength region at a wavelength of 540 to 790 nm, and the amount by which the spectral transmittance curve in the transition wavelength region shifts to the long wavelength side or the short wavelength side as the temperature rises, It can suppress compared with the absorption layer comprised only with absorption type glass, or the absorption layer containing a 2nd pigment | dye and absorption type glass. That is, this filter includes an absorption layer having a spectral transmittance curve in which temperature dependency is suppressed in the transition wavelength region.
In addition, what is necessary is just to set it as the structure and favorable conditions in 1st Embodiment other than absorption type glass, such as transparent resin B, pigment | dye A1, a reflection layer, and an antireflection layer.

(Other embodiments)
The embodiment described above is an example of a near-infrared cut filter including an absorption layer having a transition wavelength region at a wavelength of 540 to 790 nm, but is not limited thereto, and has, for example, a transition wavelength region at a wavelength of 750 to 950 nm. Widely applicable to optical filters having an absorption layer, optical filters having an absorption layer having a transition wavelength region at a wavelength of 950 to 1200 nm, optical filters having an absorption layer having a transition wavelength region at a wavelength of 350 to 540 nm, etc. The same effect can be obtained. Moreover, including the first and second embodiments, the “first and second transition wavelength regions” of the first and second absorbers can be defined as the wavelength regions described in the first embodiment.

Examples of the present invention will be described below. Note that an HR2000 high-resolution small fiber optical spectrometer manufactured by Ocean Optics was used for measurement of spectral transmittance curves of the absorption layer and the reflection layer.
Example 1
Cyclohexanone, N-methylpyrrolidone, and a squarylium compound of the formula (A1-11a) were added to a polyimide resin solution (Neoprim (registered trademark) C3G30) to prepare a coating solution for forming a resin layer. The squarylium compound of the formula (A1-11a) was 6.2 parts by mass with respect to 100 parts by mass of the polyimide resin.
This coating solution was applied onto a substrate made of CuO-containing fluorophosphate glass (produced by Asahi Glass Co., Ltd., trade name: NF-50TX) having a thickness of 0.2 mm by spin coating, and the solvent was heated and dried. A resin layer having a thickness of about 1.0 μm was formed to obtain an optical filter.

(Example 2)
In addition to cyclohexanone, N-methylpyrrolidone and the squarylium compound of the formula (A1-11a), a cyanine compound of the formula (A2-11a) is further added to 100 parts by mass of the polyimide resin in the same polyimide resin solution as in Example 1. Was added at a rate of 10.3 parts by mass to prepare a coating solution for forming an absorption layer.
This coating solution is applied onto a glass substrate having a thickness of 0.2 mm (manufactured by SCHOTT, trade name: D263) by spin coating, and the solvent is heated and dried to form an absorption layer having a thickness of about 1.0 μm. An optical filter was obtained.

(Example 3)
The cyanine compound of the formula (A2-13a) is used in place of the cyanine compound of the formula (A2-11a), and the addition amount is 4.1 parts by mass with respect to 100 parts by mass of the polyimide resin. Obtained an optical filter in the same manner as in Example 2.
Example 4
The cyanine compound of the formula (A2-13b) is used in place of the cyanine compound of the formula (A2-11a), and the addition amount is 4.3 parts by mass with respect to 100 parts by mass of the polyimide resin. Obtained an optical filter in the same manner as in Example 2.
(Example 5)
Instead of using the phthalocyanine compound (FDR-005) instead of the cyanine compound of the formula (A2-11a), the addition amount was set to a ratio of 20.1 parts by mass with respect to 100 parts by mass of the polyimide resin. An optical filter was obtained in the same manner as in Example 2.

(Example 6)
A TiO ₂ film and a SiO ₂ film were alternately laminated on the same glass substrate as in Example 2 by vapor deposition to form a reflective layer composed of 48 dielectric multilayer films. The configuration of the reflective layer was simulated by using the number of laminated dielectric multilayer films, the thickness of the TiO ₂ film, and the thickness of the SiO ₂ film as parameters, and in each spectral transmittance curve at an incident angle of 0 °, (iii-1) Specifically, to satisfy (iii-3), in this example, the average transmittance of light having a wavelength λ _{L to} 1100 nm is 10% or less and a wavelength of 430 to 550 nm in combination with the absorption layer in Example 2. The light transmittance was 90% or more, and the average transmittance of light having a wavelength λ _b ˜1100 nm was 1% or less. FIG. 2 shows the spectral transmittance curves (incidence angles of 0 ° and 30 °) of the reflective layer produced based on the above design. In this example, (iii-4) and (iii-5) were also satisfied.

Next, the absorbing layer-forming coating solution prepared in the same manner as in Example 2 was applied to the surface opposite to the reflective layer-forming surface of the glass substrate on which the reflective layer was formed by spin coating, and the solvent was added. Heat-dried to form an absorption layer having a thickness of about 1.0 μm.
After that, seven layers of TiO ₂ films and SiO ₂ films were alternately laminated on the surface of the absorption layer by vapor deposition to form an antireflection layer, thereby obtaining an optical filter.
3A shows a spectral transmittance curve (incident angle 0 °) measured at 30 ° C. and 100 ° C. for the obtained optical filter, and FIG. 3B shows a spectral transmittance curve (incident angle) measured at room temperature. 0 ° and 30 °). Thus, the obtained optical filter exhibited stable optical characteristics in which temperature dependency was suppressed and incident angle dependency was also suppressed, particularly in a spectral transmittance curve including a transition wavelength region.

(Examples 7 to 9)
An optical filter was obtained in the same manner as in Example 6 except that the coating liquid for forming the absorbent layer was the same as that prepared in Examples 3 to 5.

With respect to the obtained optical filter, a spectral transmittance curve (incidence angle 0 °) at temperatures of 30 ° C. and 100 ° C. is measured, and from the measurement result, a wavelength λ _{T30 ° C.-} 20% at which the transmittance is 20% in the transition wavelength region. and lambda _{T100 ° C.} sought _-20%, was calculated shift amount _{(nm) (= λ T100 ℃} -20% -λ T30 ℃ -20%). The results are shown in Table 3.
Table 3 also shows the shift amount of the optical filter (Comparative Example 1) using the CuO-containing fluorophosphate glass having a thickness of 0.2 mm used in Example 1. Further, in Table 3, a coating solution prepared by adding only cyclohexanone, N-methylpyrrolidone and a squarylium compound of the formula (A1-11a) to a polyimide resin solution (Neoprim (registered trademark) C3G30) is used. For the optical filter obtained in the same manner as in Example 2 (Comparative Example 2), the shift amount obtained in the same manner is also described.

  As is apparent from Table 3, all of the optical filters according to the examples of the present invention have small temperature dependency of the optical characteristics and exhibit stable optical characteristics with respect to temperature changes.

Moreover, the spectral transmittance curve (incident angle 0 degree, normal temperature) of each pigment | dye (2 types) in each absorption layer of Examples 2-5 is shown in FIGS.
As is apparent from FIGS. 4 to 7, the overlapping band of the first and second transition wavelength bands is 150 nm or more, and the overlapping band includes a wavelength at which the transmittance of each dye is 15 to 40%. It was.
Also in Example 1, the overlap band of the first and second transition wavelength regions is 150 nm or more, and the overlap band includes a wavelength at which the transmittance of the resin layer and the CuO-containing fluorophosphate glass is 20%. It was.

  Since the optical filter of the present invention has optical characteristics with low temperature dependence, it is useful as a near-infrared cut filter used in applications requiring such characteristics or in environments.

  DESCRIPTION OF SYMBOLS 11 ... Absorbing layer, 12 ... Reflective layer, 13 ... Transparent substrate, 14 ... Antireflection layer.

Claims (15)

Comprising an absorption layer comprising a first absorber and a second absorber having an absorption wavelength region at least partially overlapping at a wavelength of 350 to 1200 nm,
Each of the first absorber and the second absorber has a first transition wavelength region and a second transition wavelength region that transition from a transmission wavelength region to a cutoff wavelength region,
The first absorber shifts the spectral transmittance curve in the first transition wavelength region to the short wavelength side with increasing temperature, and the second absorber has the second transition wavelength with increasing temperature. An optical filter characterized in that the spectral transmittance curve in the region is shifted to the longer wavelength side. It has the first transition wavelength region and the second transition wavelength region at wavelengths of 540 to 790 nm, and the wavelength λ _L [nm] is the wavelength 540 of the first absorber and the second absorber. When a wavelength on the long wavelength side of the maximum absorption wavelength at ˜790 nm is used, from a dielectric multilayer film having an average transmittance of light having a wavelength λ _L ˜1100 nm of 10% or less in a spectral transmittance curve at an incident angle of 0 ° The optical filter according to claim 1, further comprising: a reflective layer.   The optical filter according to claim 1 or 2, wherein the first transition wavelength region and the second transition wavelength region have an overlapping band of 50 nm or more.   The optical filter according to claim 3, wherein at least one of a wavelength at which the first absorber exhibits a transmittance of 20% and a wavelength at which the first absorber exhibits a transmittance of 20% is included in the overlapping band. . The first absorber has wavelengths λ1 _{T30 ° C-20%} and λ1 _{T100 ° C-20% at} which the transmittance is 20% in the first transition wavelength range measured at 30 ° C and 100 ° C, respectively. And
The second absorber has wavelengths λ2 _{T30 ° C-20%} and λ2 _{T100 ° C-20% at} which the transmittance is 20% in the second transition wavelength range measured at 30 ° C and 100 ° C, respectively. And
| Λ1 _{T30 ° C.−20%} −λ1 _{T100 ° C.−20%} | ≦ 10 nm
| Λ2 _{T30 ° C.-20%} −λ2 _{T100 ° C.-20%} | ≦ 10 nm
The optical filter according to claim 1, wherein the relationship is satisfied. The absorption layer has a transition wavelength region that transitions from a transmission wavelength region to a cutoff wavelength region,
In the transition wavelength range measured at 30 ° C. and 100 ° C., the wavelengths λ _{T30 ° C.-20%} and λ _{T100 ° C.-20%} at which the transmittance is 20%, respectively,
| Λ _{T30 ° C.-20%} −λ _{T100 ° C.-20%} | ≦ 5 nm
The optical filter according to claim 1, wherein the relationship is satisfied.   The optical filter according to any one of claims 1 to 6, wherein the first absorber and the second absorber are near-infrared absorbing dyes.   The optical filter according to claim 1, wherein the absorption layer includes a first absorption layer including the first absorber and a second absorption layer including the second absorber. .   The optical filter according to claim 1, wherein the absorption layer is formed of a single layer containing a transparent resin together with the first absorber and the second absorber.   Each of the first absorber and the second absorber is at least one selected from the group consisting of a squarylium compound, a cyanine compound, a phthalocyanine compound, a naphthalocyanine compound, a dithiol metal complex compound, and a diimonium compound. The optical filter according to claim 1, which is a seed. The first absorber is a squarylium compound represented by the formula (A1-11), and the second absorber is a cyanine represented by the formula (A2-11) or the formula (A2-13). The optical filter according to claim 10, which is a system compound.

  The optical filter according to claim 1, wherein the absorption layer has a first absorption layer containing a transparent resin together with a near-infrared absorbing dye, and a second absorption layer containing a near-infrared absorption glass.   The near infrared absorbing dye is at least one selected from the group consisting of squarylium compounds, cyanine compounds, phthalocyanine compounds, naphthalocyanine compounds, dithiol metal complex compounds and diimonium compounds, and the near infrared absorption The optical filter according to claim 12, wherein the glass is a fluorophosphate-based glass or a phosphate-based glass containing CuO. The optical filter according to claim 13, wherein the near-infrared absorbing dye is a squarylium-based compound represented by the formula (A1-11).

  The imaging device provided with the optical filter of any one of Claims 1-14.

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