阅读说明：本技术 近红外线截止滤波器 (Near infrared cut-off filter ) 是由 长田崇 于 2021-05-12 设计创作，主要内容包括：一种近红外线截止滤波器,能够在大的入射角度范围内有意地抑制可见光区域的反射率。近红外线截止滤波器具有透明基板、光学多层膜、第一匹配膜、设置于最外侧的第二匹配膜,第一匹配膜设置在光学多层膜上、或设置在透明基板与光学多层膜之间,在该近红外线截止滤波器中,将从第二匹配膜侧以5°的入射角度入射的光的正反射率设为第一反射率R-(1),将以40°的入射角度入射的光的正反射率设为第二反射率R-(2),将波长480nm～680nm的范围的R-(1)的近似直线设为y-(1),将波长450nm～650nm的范围的R-(2)的近似直线设为y-(2)时,R-(1)与y-(1)的值之间的差的绝对值的最大值ΔR-(1)小于5％,R-(2)与y-(2)的值之间的差的绝对值的最大值ΔR-(2)小于6％。(A near infrared cut filter capable of intentionally suppressing the reflectance in the visible light region in a wide incident angle range. The near infrared cut filter includes a transparent substrate, an optical multilayer film, a first matching film provided on the optical multilayer film or between the transparent substrate and the optical multilayer film, and a second matching film provided on the outermost side, and has a first reflectance R defined as a regular reflectance of light incident at an incident angle of 5 DEG from the second matching film side 1 The second reflectance R is the regular reflectance of light incident at an incident angle of 40 ° 2 R with a wavelength of 480nm to 680nm 1 Is set as y 1 R with a wavelength of 450nm to 650nm 2 Is set as y 2 When R is 1 And y 1 Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R 1 Less than 5%, R 2 And y 2 Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R 2 Less than 6%.)

1. A near infrared ray cut filter, comprising:

a transparent substrate having a first surface;

an optical multilayer film provided on the first surface side of the transparent substrate;

a first matching film provided on the first surface side of the transparent substrate;

a second matching film disposed at an outermost side of the first surface,

the optical multilayer film has an alternating laminated structure of a high refractive index layer and a low refractive index layer, has a function of reflecting near infrared rays,

the first matching film and the second matching film have a function of suppressing reflection of visible light,

the first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film,

in the near-infrared ray cut-off filter,

the regular reflectance of light incident at an incident angle of 5 ° from the second matching film side is set as a first reflectance R₁And the regular reflectance of light incident from the second matching film side at an incident angle of 40 ° is defined as a second reflectance R₂，

The first reflectance R in the range of 480nm to 680nm₁Is set as y₁The second reflectance R in the wavelength range of 450nm to 650nm₂Is set as y₂When the temperature of the water is higher than the set temperature,

the first reflectance R at the same wavelength in the range of 480nm to 680nm₁And the approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

the second reflectance R at the same wavelength in the wavelength range of 450 nm-650 nm₂And the approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

2. The near infrared ray cutoff filter according to claim 1,

the first matching film has an alternating laminated structure of high refractive index layers and low refractive index layers,

QWOT at wavelength of 550nm of the high refractive index layer is set to Q_HQWOT at wavelength of 550nm of the low refractive index layer is set as Q_LWhen the temperature of the water is higher than the set temperature,

the first matching film has the following structure from the transparent substrate side:

(H₁Q_H，L₁Q_L，H₂Q_H，L₂Q_L，……H_nQ_H，L_nQ_L)

where n is a natural number of 1 or more,

each coefficient satisfies the following formula:

1.7≤(H₁+H₂+…+H_n)/(L₁+L₂+…+L_n)≤2.5。

3. the near infrared ray cut filter according to claim 1 or 2,

the first matching film is composed of 6 or more layers.

4. The near-infrared ray cut filter according to any one of claims 1 to 3,

the second matching film has a two-layer structure of a high refractive index layer and a low refractive index layer,

QWOT at wavelength of 550nm of the high refractive index layer is set to Q_AQWOT at wavelength of 550nm of the low refractive index layer is set as Q_BWhen the temperature of the water is higher than the set temperature,

the second matching film has the following structure from the transparent substrate side:

(XQ_A，YQ_B)

here, X > Y.

5. The near-infrared ray cut filter according to any one of claims 1 to 4,

a third matching film having an alternating laminated structure of a high refractive index layer and a low refractive index layer on the first surface side,

the optical multilayer film is disposed between the first matching film and the third matching film.

6. The near infrared ray cutoff filter according to claim 5,

the third matching film is composed of the same number of layers as the first matching film.

7. The near-infrared ray cut filter according to any one of claims 1 to 6,

the optical multilayer film has a transmission band in a visible light region.

8. The near infrared ray cutoff filter according to claim 7,

the optical multilayer film has a reflection band in a near ultraviolet region.

Technical Field

The present invention relates to a near infrared ray cut filter.

Background

An imaging device such as a digital camera or a digital video camera includes a solid-state imaging element (image sensor) for sensing a person, a scene, or the like. However, the solid-state image pickup element exhibits a stronger sensitivity to infrared light than the human vision. Therefore, a near infrared cut filter is also provided in the imaging device in order to make an image obtained by the solid-state imaging element closer to the human visual sensitivity.

Generally, such a near-infrared cut filter is configured by providing an optical multilayer film that shields near-infrared rays on a transparent substrate. The optical multilayer film is formed by coating a high refractive index dielectric (e.g., TiO)₂) Films of and dielectrics of low refractive index (e.g. SiO)₂) The constituent films are alternately laminated.

[ Prior Art document ]

[ patent document ]

[ patent document 1 ] International publication No. WO2014/104370

[ problem to be solved by the invention ]

In a near infrared ray cut filter having an optical multilayer film, it is known that optical characteristics often change depending on the angle of incident light. Therefore, for example, the following problems arise: the problem is that even if desired optical characteristics are obtained for light energy having an incident angle close to the normal direction, desired optical characteristics are not obtained for light having an incident angle greatly deviated from the normal direction.

Further, the incident angle dependency of the optical characteristics of the near infrared ray cut filter becomes a problem in the point of image clarity when the near infrared ray cut filter is applied to a solid-state imaging device. For example, if a part of the visible light incident on the near infrared cut filter is reflected without being transmitted, such reflected light causes stray light.

Disclosure of Invention

The present invention has been made in view of such a background, and an object of the present invention is to provide a near infrared cut filter capable of intentionally suppressing the reflectance in the visible light region in a wide incident angle range.

[ MEANS FOR solving PROBLEMS ] A method for solving the problems

In the present invention, there is provided a near infrared cut filter comprising:

a transparent substrate having a first surface;

an optical multilayer film provided on the first surface side of the transparent substrate;

a first matching film provided on the first surface side of the transparent substrate;

a second matching film disposed at an outermost side of the first surface,

the optical multilayer film has an alternating laminated structure of a high refractive index layer and a low refractive index layer, has a function of reflecting near infrared rays,

the first matching film and the second matching film have a function of suppressing reflection of visible light,

the first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film,

in the near-infrared ray cut-off filter,

the regular reflectance of light incident at an incident angle of 5 ° from the second matching film side is set as a first reflectance R₁And the regular reflectance of light incident from the second matching film side at an incident angle of 40 ° is defined as a second reflectance R₂，

The first reflectance R in the range of 480nm to 680nm₁Is set as y₁The second reflectance R in the wavelength range of 450nm to 650nm₂Is set as y₂When the temperature of the water is higher than the set temperature,

the first reflectance R at the same wavelength in the range of 480nm to 680nm₁And the approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

the second reflectance R at the same wavelength in the wavelength range of 450 nm-650 nm₂And the approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

[ Effect of the invention ]

In the present invention, a near infrared cut filter capable of intentionally suppressing the reflectance in the visible light region in a large incident angle range can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view of a near-infrared cut filter according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a near-infrared cut filter according to another embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of a near-infrared cut filter according to still another embodiment of the present invention.

Fig. 4 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained in the near-infrared cut filter of example 1.

Fig. 5 is a graph showing a part of the optical characteristics of 5 ° incidence in fig. 4 in an enlarged manner.

Fig. 6 is a graph showing a part of the optical characteristics of the 40 ° incident light of fig. 4 in an enlarged manner.

Fig. 7 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained in the near-infrared cut filter of example 2.

Fig. 8 is a graph showing a part of the optical characteristics of fig. 7 at 5 ° incidence in an enlarged manner.

Fig. 9 is a partially enlarged graph showing the optical characteristics of fig. 7 at 40 ° incidence.

Fig. 10 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained in the near-infrared cut filter of example 3.

Fig. 11 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained in the near-infrared cut filter of example 4.

Fig. 12 is a partially enlarged graph showing the optical characteristics of fig. 11 at 5 ° incidence.

Fig. 13 is a partially enlarged graph showing the optical characteristics of fig. 11 at 40 ° incidence.

Fig. 14 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained by the near-infrared cut filter of example 11.

Fig. 15 is a graph showing a part of the optical characteristics of fig. 14 at 5 ° incidence in an enlarged manner.

Fig. 16 is a partially enlarged graph showing the optical characteristics of fig. 14 at 40 ° incidence.

Fig. 17 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained by the near-infrared cut filter of example 11.

Fig. 18 is a partially enlarged graph showing the optical characteristics of fig. 17 at 5 ° incidence.

Fig. 19 is a partially enlarged graph showing the optical characteristics of fig. 17 at 40 ° incidence.

Fig. 20 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained by the near-infrared cut filter of example 13.

Fig. 21 is a graph showing optical characteristics of 5 ° incidence and 40 ° incidence obtained by the near-infrared cut filter of example 14.

[ Mark Specification ]

100 first optical filter

110 transparent substrate

112 first surface

120 optical multilayer film

140 first matching film

160 second matching film

200 second optical filter

210 transparent substrate

212 first surface

220 optical multilayer film

240 first matching film

260 second matching film

300 third optical filter

310 transparent substrate

312 first surface

320 optical multilayer film

340 first matching film

350 third matching film

360 second matching film

Detailed Description

An embodiment of the present invention is explained below.

In one embodiment of the present invention, there is provided a near-infrared cut filter including:

a transparent substrate having a first surface;

an optical multilayer film provided on the first surface side of the transparent substrate;

a first matching film provided on the first surface side of the transparent substrate;

a second matching film disposed at an outermost side of the first surface,

the optical multilayer film has an alternating laminated structure of a high refractive index layer and a low refractive index layer, has a function of reflecting near infrared rays,

the first matching film and the second matching film have a function of suppressing reflection of visible light,

the first matching film is disposed on the optical multilayer film or between the transparent substrate and the optical multilayer film,

in the near-infrared ray cut-off filter,

the regular reflectance of light incident at an incident angle of 5 ° from the second matching film side is set as a first reflectance R₁And the regular reflectance of light incident from the second matching film side at an incident angle of 40 ° is defined as a second reflectance R₂，

The first reflectance R in the range of 480nm to 680nm₁Is set as y₁The second reflectance R in the wavelength range of 450nm to 650nm₂Is set as y₂When the temperature of the water is higher than the set temperature,

the first reflectance R at the same wavelength in the range of 480nm to 680nm₁And the approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

at a wavelength of 45The second reflectance R at the same wavelength in the range of 0nm to 650nm₂And the approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

The near-infrared cut filter according to an embodiment of the present invention includes an optical multilayer film. The optical multilayer film has a function of blocking transmission of near infrared rays and reflecting the near infrared rays.

In addition, the near-infrared cut filter according to one embodiment of the present invention includes a first matching film and a second matching film. The first matching film and the second matching film have a function of suppressing reflection of visible light.

In addition, the near infrared cut filter according to an embodiment of the present invention is characterized in that the first reflectance R at the same wavelength is in a range of 480nm to 680nm₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5%. In addition, the near infrared cut filter according to an embodiment of the present invention is characterized in that the second reflectance R at the same wavelength is within a range of 450nm to 650nm in the wavelength₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

In the near infrared cut filter having such a structure, as will be described in detail later, the reflectance in the visible light region can be intentionally suppressed in a wide incident angle range. Therefore, when the near-infrared cut filter according to the embodiment of the present invention is applied to a solid-state imaging device, a clear image can be obtained.

(near-infrared ray cut filter according to one embodiment of the present invention)

Next, an embodiment of the present invention will be described in more detail with reference to the drawings.

Fig. 1 schematically shows a cross section of a near-infrared cut filter (hereinafter, referred to as a "first optical filter") according to an embodiment of the present invention.

As shown in fig. 1, the first optical filter 100 has: a transparent substrate 110 having a first surface 112; an optical multilayer film 120; a first matching film 140; and a second matching film 160.

The optical multilayer film 120 is disposed on the first surface 112 of the transparent substrate 110, and the first matching film 140 is disposed on the optical multilayer film 120. Also, the second matching film 160 is disposed at the outermost side of the first surface 112.

The optical multilayer film 120 has a function of blocking transmission of near infrared rays and reflecting the near infrared rays. The first matching film 140 and the second matching film 160 have a function of suppressing reflection of visible light.

Here, the regular reflectance of light incident from the second matching film 160 side at an incident angle of 5 ° with respect to the normal line is referred to as a first reflectance R₁The regular reflectance of light incident at an incident angle of 40 ° with respect to the normal is referred to as a second reflectance R₂. The first reflectance R with a wavelength of 480nm to 680nm is adjusted₁Is set as y₁A second reflectance R with a wavelength of 450nm to 650nm₂Is set as y₂。

In this case, the first optical filter 100 has the following features:

a first reflectance R at the same wavelength in the range of 480nm to 680nm₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

a second reflectance R at the same wavelength in the wavelength range of 450nm to 650nm₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

For example,. DELTA.R₁It may also be less than 4%, preferably less than 3%. And, for example,. DELTA.R₂It may also be less than 5.5%, preferably less than 5%.

In the first optical filter 100, the reflectance in the visible light region can be intentionally suppressed in a large incident angle range. Therefore, when the first optical filter 100 is applied to a solid-state imaging device, a clear image can be obtained.

(near-infrared ray cut filter according to another embodiment of the present invention)

Next, another embodiment of the present invention will be described with reference to fig. 2.

Fig. 2 schematically shows a cross section of a near-infrared cut filter (hereinafter, referred to as "second optical filter") according to another embodiment of the present invention.

As shown in fig. 2, the second optical filter 200 includes: a transparent substrate 210 having a first surface 212; a first matching film 240; an optical multilayer film 220; and a second matching film 260.

A first matching film 240 is disposed on the first surface 212 of the transparent substrate 210, and an optical multilayer film 220 is disposed on the first matching film 240. Also, the second matching film 260 is disposed at the outermost side of the first surface 212.

Here, the second optical filter 200 has the following features as well as the first optical filter 100:

a first reflectance R at the same wavelength in the range of 480nm to 680nm₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

a second reflectance R at the same wavelength in the wavelength range of 450nm to 650nm₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

In the second optical filter 200, the reflectance in the visible light region can be intentionally suppressed in a large incident angle range. Therefore, when the second optical filter 200 is applied to a solid-state imaging device, a clear image can be obtained.

(near-infrared cut filter according to still another embodiment of the present invention)

Next, still another embodiment of the present invention will be described with reference to fig. 3.

Fig. 3 schematically shows a cross section of a near-infrared cut filter (hereinafter, referred to as a "third optical filter") according to still another embodiment of the present invention.

As shown in fig. 3, the third optical filter 300 includes: a transparent substrate 310 having a first surface 312; a first matching film 340; an optical multilayer film 320; a third matching film 350; and a second matching film 360.

The first matching film 340 is disposed on the first surface 312 of the transparent substrate 310. Further, the optical multilayer film 320 is disposed on the first matching film 340, and the third matching film 350 is disposed on the optical multilayer film 320. Further, a second matching film 360 is disposed at the outermost side of the first surface 312.

Here, the third optical filter 300 has the following characteristics, as with the first optical filter 100 and the second optical filter 200:

a first reflectance R at the same wavelength in the range of 480nm to 680nm₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁Less than 5 percent of the total weight of the composition,

a second reflectance R at the same wavelength in the wavelength range of 450nm to 650nm₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂Less than 6%.

In the third optical filter 300, the reflectance in the visible light region can be intentionally suppressed in a large incident angle range. Therefore, when the third optical filter 300 is applied to a solid-state imaging device, a clear image can be obtained.

(constituent Member)

Next, each member constituting the near-infrared cut filter according to an embodiment of the present invention will be described in more detail.

Here, the constituent members of the third optical filter 300 will be described as an example. Therefore, when referring to each member, the reference numerals shown in fig. 3 are used.

(transparent substrate 310)

The transparent substrate 310 may be made of any material as long as it is transparent (has high transmittance) to visible light. For example, the transparent substrate 310 may be made of glass (white plate glass, near infrared ray absorbing glass, or the like) or resin.

(optical multilayer film 320)

The optical multilayer film 320 has a repeating structure of a "high refractive index layer" and a "low refractive index layer" and has a function of reflecting near infrared rays (wavelength 750nm to 900 nm).

In the present application, the "high refractive index layer" means a layer having a refractive index of 2.0 or more at a wavelength of 500nm, and the "low refractive index layer" means a layer having a refractive index of 1.6 or less at a wavelength of 500 nm.

Examples of the high refractive index layer include titanium oxide, tantalum oxide, and niobium oxide. Examples of the low refractive index layer include silicon oxide and magnesium fluoride. For example, the refractive index of titanium oxide at a wavelength of 500nm is generally in the range of 2.3 to 2.8, and the refractive index of silicon oxide is generally in the range of 1.4 to 1.5, although it is also influenced by the crystal state.

The number of layers of the optical multilayer film 320 is not particularly limited, and is, for example, in the range of 4 to 100. The number of layers is preferably in the range of 6 to 24.

In addition, half of the number of layers of the multilayer film (in the case of mantissa, decimal point or less is omitted) is also referred to as "number of inversions (n)".

The number of repetitions n of the optical multilayer film 320 is in the range of 2 to 50, preferably in the range of 3 to 13.

The total thickness (physical film thickness) of the optical multilayer film 320 is, for example, in the range of 200nm to 10 μm, and preferably in the range of 1 μm to 6 μm.

The optical multilayer film 320 may also have a function of reflecting near ultraviolet rays and infrared rays (wavelength 900nm to 1200 nm). In this case, the third optical filter 300 can shield near ultraviolet rays and infrared rays.

(first matching film 340)

As described above, the first matching film 340 has a function of suppressing reflection of visible light.

The first matching film 340 may also have an alternating stacked structure of "high refractive index layers" and "low refractive index layers". As the "high refractive index layer" and the "low refractive index layer", the above description can be referred to.

In the case where the first matching film 340 has an alternating stacked structure of high refractive index layers and low refractive index layers, QWOT (Quarter-wave Optical Thickness) at a wavelength of 550nm of the high refractive index layers is to be formedLong optical thickness) to Q_HQWOT at wavelength of 550nm of the low refractive index layer is set as Q_LIn this case, the first matching film 340 may have the following structure in order from the transparent substrate 310 side:

(H₁Q_H，L₁Q_L，H₂Q_H，L₂Q_L，……，H_nQ_H，L_nQ_L) Formula (1) (here, n is a natural number of 1 or more). Moreover, each coefficient may also satisfy the following formula:

w is more than or equal to 1.7 and less than or equal to 2.5 (2)

. In this case, the amount of the solvent to be used,

W＝(H₁+H₂+…+H_n)/(L₁+L₂+…+L_n) (3) formula (II).

(1) In the formula Q_HAnd Q_LFormer H₁…H_nAnd L₁…L_nThe coefficients indicate how much the physical film thickness of each layer is a multiple of QWOT. I.e. H_nQ_HAnd L_nQ_LEtc. represent the optical film thickness of each layer.

The number of layers of the first matching film 340 is not particularly limited, but is preferably in the range of 2 to 20 layers, for example. When the number of layers exceeds 20, it takes time to form the film, and the manufacturing cost of the third optical filter 300 increases. The number of layers of the first matching film 340 is more preferably in the range of 6 to 16 layers, and still more preferably 12 or less.

(second matching film 360)

The second matching film 360 has a function of suppressing reflection of visible light, similarly to the first matching film 340.

The second matching film 360 preferably has a two-layer structure of a high refractive index layer and a low refractive index layer (that is, the repetition number n is 1). The "high refractive index layer" and the "low refractive index layer" may be referred to the above description.

In this case, QWOT at a wavelength of 550nm of the high refractive index layer is defined as Q_AQWOT at wavelength of 550nm of the low refractive index layer is set as Q_BWhen, the second matching film 360 has the following structure from the transparent substrate side:

(XQ_A，YQ_B) (4) formula

Here, X > Y is preferred.

(third matching film 350)

The third matching film 350 has a function of suppressing reflection of visible light, similarly to the first matching film 340 and the second matching film 360.

The third matching film 350 may also have an alternating stacked structure of "high refractive index layers" and "low refractive index layers". As the "high refractive index layer" and the "low refractive index layer", the above description can be referred to.

In particular, the third matching film 350 may be formed of the same number of layers as the first matching film 340. The third matching film 350 may be configured to satisfy the above-described expressions (1) to (3).

For example, the third matching film 350 may be formed of 6 to 16 layers. In this case, the number of repetitions n is 3 to 8.

The third matching film 350 is not necessarily structured, but reflection of visible light can be further suppressed by providing the third matching film 350.

In the example shown in fig. 3, the third matching film 350 is disposed on the optical multilayer film 320 provided on the first matching film 340. However, conversely, the third matching film 350 may be disposed between the transparent substrate 310 and the optical multilayer film 320, and the first matching film 340 may be disposed on the optical multilayer film 320.

The above description has been given of the respective members included in the near-infrared cut filter according to the embodiment of the present invention, taking the third optical filter 300 as an example. However, it is obvious to those skilled in the art that the above description can be applied to the first optical filter 100 and the second optical filter 200 as well.

[ examples ] A method for producing a compound

Next, an embodiment of the present invention is explained. In the following description, examples 1 to 4 are examples, and examples 11 to 14 are comparative examples.

Optical characteristics of the near-infrared cut filters having the structures shown in the following examples were evaluated. The optical properties were evaluated using commercially available optical simulation Software (TFCalc from Software SPectra, Inc.).

In the following evaluation, the reflectance of the near-infrared cut filter indicates a regular reflectance obtained when light is made incident at a predetermined angle with respect to a normal line from the first surface side of the transparent substrate (i.e., the side on which the various films are provided).

The incident angles of light are 5 ° and 40 ° with respect to the normal. Hereinafter, the incidence directions thereof are referred to as "5 ° incidence" and "40 ° incidence", respectively.

(example 1)

The near infrared ray cut filter of example 1 has a structure shown in fig. 1.

Glass (D263; manufactured by Schott) was used as the transparent substrate. In other examples, the same glass is used.

The optical multilayer film is a low refractive index layer (SiO)₂Layer) and high refractive index layer (TiO)₂Layers). The number of layers was set to 17. Further, the first matching film is made of TiO₂Layer and SiO₂The number of layers was 6 in the repeating structure. Further, the second matching film is made of TiO₂Layer and SiO₂A bilayer structure of layers.

In table 1 below, the layer structures of the optical multilayer film, the first matching film, and the second matching film used in example 1 are collectively shown.

[ TABLE 1 ]

In the first matching film, the value of W represented by the aforementioned formula (3), i.e., (H)₁+H₂+H₃)/(L₁+L₂+L₃) The value of (A) is 2.20.

In addition, in the second matching film, TiO₂QWOT (Q) of layer at wavelength 550nm_A)＝1.898，SiO₂QWOT (Q) of layer at wavelength 550nm_B) Is 0.887. In addition, the above-mentioned table of formula (4) is usedIn the case of the second matching film, X/Y is 2.14.

In table 1, since the layers are described in order of proximity to the transparent substrate, the layers are disposed on the transparent substrate from the upper side to the lower side of table 1. These descriptions are also given in tables 2 to 8 below.

(example 2)

The near infrared ray cut filter of example 2 has a structure shown in fig. 1.

Glass is used for the transparent substrate.

The optical multilayer film is made of TiO₂Layer and SiO₂The repetitive structure of (1). The number of layers was set to 18. Further, the first matching film is made of TiO₂Layer and SiO₂The number of layers is 6. Further, the second matching film is made of TiO₂Layer and SiO₂A bilayer structure of layers.

In table 2 below, the layer structures of the optical multilayer film, the first matching film, and the second matching film used in example 2 are collectively shown.

[ TABLE 2 ]

In the first matching film, the value of W represented by the aforementioned formula (3), i.e., (H)₁+H₂+H₃)/(L₁+L₂+L₃) The value of (A) is 1.71.

In addition, in the second matching film, TiO₂QWOT (Q) of layer at wavelength 550nm_A)＝2.000，SiO₂QWOT (Q) of layer at wavelength 550nm_B) Is 0.900. When the second matching film is expressed by the above formula (4), X/Y is 2.22.

(example 3)

The near infrared ray cut filter of example 3 has a structure shown in fig. 2.

Glass is used for the transparent substrate.

The first matching film is made of TiO₂Layer and SiO₂The number of layers is 6. And alsoThe optical multilayer film is made of SiO₂Layer and TiO₂The repetitive structure of the layers. The number of layers was set to 17. Further, the second matching film is made of TiO₂Layer and SiO₂A bilayer structure of layers.

In table 3 below, the layer structures of the first matching film, the optical multilayer film, and the second matching film used in example 3 are collectively shown.

[ TABLE 3 ]

In the first matching film, the value of W represented by the aforementioned formula (3), i.e., (H)₁+H₂+H₃)/(L₁+L₂+L₃) The value of (A) was 2.09.

In addition, in the second matching film, TiO₂QWOT (Q) of layer at wavelength 550nm_A)＝1.587，SiO₂QWOT (Q) of layer at wavelength 550nm_B) Is 0.884. When the second matching film is expressed by the above formula (4), X/Y is 1.80.

(example 4)

The near infrared ray cut filter of example 4 has a structure shown in fig. 3.

Glass is used for the transparent substrate.

The first matching film is made of SiO₂Layer and TiO₂The number of layers was 6 in the repeating structure. Further, the optical multilayer film is made of SiO₂Layer and TiO₂The repetitive structure of the layers. The number of layers was set to 17. Further, the third matching film is made of TiO₂Layer and SiO₂The number of layers was 6 in the repeating structure. Further, the second matching film is made of TiO₂Layer and SiO₂A bilayer structure of layers.

In table 4 below, the layer structures of the first matching film, the optical multilayer film, the third matching film, and the second matching film used in example 4 are collectively shown.

[ TABLE 4 ]

In the first matching film, the value of W represented by the aforementioned formula (3), i.e., (H)₁+H₂+H₃)/(L₁+L₂+L₃) The value of (A) is 2.15.

In addition, in the second matching film, TiO₂QWOT (Q) of layer at wavelength 550nm_A)＝1.983，SiO₂QWOT (Q) of layer at wavelength 550nm_B) Is 0.921. When the second matching film is expressed by the above formula (4), X/Y is 2.15.

(example 11)

The near-infrared cut filter in example 11 has a structure having only an optical multilayer film on a transparent substrate. The optical multilayer film is made of TiO₂Layer and SiO₂The number of layers was 20 in the repeating structure.

Table 5 below shows the layer structure of the optical multilayer film used in example 11.

[ TABLE 5 ]

(example 12)

The near-infrared cut filter in example 12 has a structure having only an optical multilayer film on a transparent substrate. The optical multilayer film is made of SiO₂Layer and TiO₂The number of layers was 21 in the repeating structure.

Table 6 below shows the layer structure of the optical multilayer film used in example 12.

[ TABLE 6 ]

(example 13)

The near-infrared cut filter in example 13 has a structure in which an optical multilayer film and a first matching film are arranged in this order on a transparent substrate.

Optical systemThe multilayer film is made of SiO₂Layer and TiO₂The number of layers was 17 in the repeating structure. Further, the first matching film is made of TiO₂Layer and SiO₂The number of layers was 6 in the repeating structure.

Table 7 below shows the layer structures of the optical multilayer film and the first matching film used in example 13.

[ TABLE 7 ]

(example 14)

The near-infrared cut filter in example 14 has the structure shown in fig. 1.

Glass is used for the transparent substrate.

The optical multilayer film is made of SiO₂Layer and TiO₂The repetitive structure of the layers. The number of layers was set to 17. Further, the first matching film is made of TiO₂Layer and SiO₂The number of layers was 6 in the repeating structure. Further, the second matching film is made of TiO₂Layer and SiO₂A bilayer structure of layers.

Table 8 below shows the layer structures of the optical multilayer film, the first matching film, and the second matching film used in example 14.

[ TABLE 8 ]

(evaluation results of optical Properties)

(near-infrared ray cut filter in example 1)

Fig. 4 to 6 show the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 1.

In fig. 4, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 4, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

As is clear from the results of fig. 4, the near-infrared cut filter in example 1 has a transmission band in the visible light region (wavelength of about 450nm to about 650nm) and a reflection band in the near-infrared region.

The wavelength range of the reflection band at 5 ° incidence is in the range of about 750nm to about 1000nm, whereas the wavelength range of the reflection band at 40 ° incidence is in the range of about 700nm to about 900 nm. That is, the wavelength range of the reflection band at 40 ° incidence is shifted to the lower wavelength side than the wavelength range of the reflection band at 5 ° incidence.

However, it can be seen that the first reflectance R is not the same₁And a second reflectance R₂In the case of any of the above, the reflection can be sufficiently suppressed in the transmission band.

In FIG. 5, the first reflectance R in the range of 480nm to 680nm in the trace shown in FIG. 4₁The change of (a) is shown in an enlarged scale.

In fig. 5, a straight line y₁A first reflectance R in a wavelength range of 480nm to 680nm₁Is represented by the following equation:

y₁0.0353 λ -16.087 (5).

Here, λ is a wavelength (the same applies hereinafter).

In FIG. 6, the second reflectance R in the range of 450nm to 650nm is shown in the trace shown in FIG. 4₂The change of (a) is shown in an enlarged scale.

Line y of FIG. 6₂A second reflectance R in a wavelength range of 450nm to 650nm₂Is represented by the following equation:

y₂0.0532 lambda-24.315 (6).

From the above results, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝2.35％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝5.38％。

(near-infrared ray cut filter in example 2)

Fig. 7 to 9 show the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 2.

In fig. 7, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 7, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 7, it is understood that the near infrared cut filter of example 2 has a transmission band in the visible light region (wavelength of about 450nm to about 650nm) and a reflection band in the near infrared region.

In the transmission band, it is found that the first reflectance R is not observed₁And a second reflectance R₂In any case, the reflection can be sufficiently suppressed.

In FIG. 8, the first reflectance R in the range of 480nm to 680nm in the trace shown in FIG. 7₁The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 8₁A first reflectance R in a wavelength range of 480nm to 680nm₁Is represented by the following equation:

y₁-0.0046 λ +4.6073 (7).

In FIG. 9, the second reflectance R in the range of 450nm to 650nm is shown in the trace shown in FIG. 7₂The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 9₂A second reflectance R in a wavelength range of 450nm to 650nm₂Is represented by the following equation:

y₂0.008 λ -2.0209 (8).

From the above results, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝3.25％。

In addition, the second inverse at the same wavelength is obtainedRefractive index R₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝3.98％。

(near-infrared ray cut filter in example 3)

Fig. 10 shows the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 3.

In fig. 10, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 10, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

As is clear from the results of fig. 10, the near-infrared cut filter of example 3 has a transmission band in the visible light region (wavelength of about 450nm to about 650nm) and a reflection band in the near-infrared region.

In addition, it can be seen that the first reflectance R is not observed in the transmission band₁And a second reflectance R₂In any case, the reflection can be sufficiently suppressed.

From the obtained result, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝1.27％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝4.41％。

(near-infrared ray cut filter in example 4)

Fig. 11 to 13 show the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 4.

In fig. 11, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 11, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 11, it is understood that the near infrared cut filter of example 4 has a transmission band in the visible light region (wavelength of about 450nm to about 650nm) and a reflection band in the near infrared region.

In addition, it can be seen that the first reflectance R is not observed in the transmission band₁And a second reflectance R₂In any case, the reflection can be sufficiently suppressed.

In FIG. 12, the first reflectance R in the range of 480nm to 680nm in the line trace shown in FIG. 11₁The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 12₁A first reflectance R in a wavelength range of 480nm to 680nm₁Is represented by the following equation:

y₁(0.0026. lamda. -0.8325 (9)).

In FIG. 13, the second reflectance R in the range of 450nm to 650nm in the line trace shown in FIG. 11₂The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 13₂A second reflectance R in a wavelength range of 450nm to 650nm₂Is represented by the following equation:

y₂0.015 λ -6.6515 (10).

From the above results, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝1.03％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝4.98％。

(near Infrared ray cut filter in example 11)

Fig. 14 to 16 show the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 11.

In fig. 14, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 14, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 14, in the case of the near-infrared cut filter of example 11, a decrease in reflectance was observed in the visible light region regardless of the incidence of 5 ° or 40 °. However, it can be seen that in this region, the first reflectance R₁And a second reflectance R₂The value of (c) is not so suppressed.

In FIG. 15, the first reflectance R in the range of 480nm to 680nm in the line trace shown in FIG. 14₁The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 15₁A first reflectance R in a wavelength range of 480nm to 680nm₁Is represented by the following equation:

y₁0.0735 lambda-27.775 (11).

In FIG. 16, the second reflectance R in the range of 450nm to 650nm is shown in the trace shown in FIG. 14₂The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 16₂A second reflectance R in a wavelength range of 450nm to 650nm₂Is represented by the following equation:

y₂0.0747 lambda-27.467 (12).

From the above results, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝17.56％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝12.93％。

(near Infrared ray cut filter in example 12)

Fig. 17 to 19 show the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 12.

In fig. 17, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 17, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 17, in the case of the near infrared ray cut filter of example 12, the first reflectance R was not observed₁And a second reflectance R₂In the case of any of the above, a decrease in reflectance was observed in the visible light region. However, it can be seen that in this region, the first reflectance R₁And a second reflectance R₂The value of (c) is not so suppressed.

In FIG. 18, the first reflectance R in the range of 480nm to 680nm in the line trace shown in FIG. 17₁The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 18₁Is a first reflectance R in the wavelength range of 480nm to 680nm₁Is represented by the following equation:

y₁0.0435 lambda-20.496 (13).

In FIG. 19, the second reflectance R in the range of 450nm to 650nm is shown in the trace shown in FIG. 17₂The change of (a) is shown in an enlarged scale.

Straight line y in FIG. 19₂A second reflectance R in a wavelength range of 450nm to 650nm₂Is represented by the following equation:

y₂0.044 λ -19.138 (14).

From the above results, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝6.75％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝5.35％。

(near Infrared ray cut filter in example 13)

Fig. 20 shows the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 13.

In FIG. 20, the horizontal axis represents wavelength and the vertical axis represents wavelengthIs the reflectivity. In fig. 20, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 20, in the case of the near infrared ray cut filter in example 13, the reflectance R was not measured at all at the first reflectance R₁And a second reflectance R₂In the case of any of the above, a decrease in reflectance was observed in the visible light region. However, it can be seen that in this region, the first reflectance R₁And a second reflectance R₂The value of (c) is not so suppressed.

From the obtained result, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝10.10％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝10.30％。

(near Infrared ray cut filter in example 14)

Fig. 21 shows the evaluation results of the optical characteristics obtained in the near-infrared cut filter of example 14.

In fig. 21, the horizontal axis represents wavelength and the vertical axis represents reflectance. In fig. 21, the first reflectance R, which is the regular reflectance obtained at 5 ° incidence, is shown₁And a second reflectance R, which is a regular reflectance obtained at 40 DEG incidence₂The results of (A) are also shown.

From the results of fig. 21, in the case of the near infrared ray cut filter of example 14, the first reflectance R was not observed₁And a second reflectance R₂In the case of any of the above, a decrease in reflectance was observed in the visible light region. However, it can be seen that in this region, the first reflectance R₁And a second reflectance R₂The value of (c) is not so suppressed.

From the obtained result, the first reflectance R at the same wavelength is obtained₁And an approximate straight line y₁Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₁When it is changed to Δ R₁＝10.30％。

In addition, the second reflectivity R at the same wavelength is obtained₂And an approximate straight line y₂Of the absolute value of the difference between the values of (a) and (b) is a maximum value Δ R₂When it is changed to Δ R₂＝14.77％。

In table 9 below, Δ R obtained in the near-infrared cut filter of each example is shown₁And Δ R₂The values of (A) are also indicated.

[ TABLE 9 ]

Thus, when Δ R is satisfied₁<5% and. DELTA.R₂<In the 6% near-infrared cut filters of examples 1 to 4, it was confirmed that reflection of light at the transmission band can be intentionally suppressed regardless of the incident angle of light.