JP6962322B2 - Near infrared cut filter glass - Google Patents

Description

The present invention relates to a near-infrared cut filter glass that is used in a color correction filter of a digital still camera, a color video camera, or the like, and is particularly excellent in light transmission in the visible range.

Solid-state imaging devices such as CCDs and CMOSs used in digital still cameras and the like have spectral sensitivities ranging from the visible region to the near-infrared region near 1200 nm. Therefore, since good color reproducibility cannot be obtained as it is, the luminosity factor is corrected by using a near-infrared cut filter glass to which a specific substance that absorbs infrared rays is added. As this near-infrared cut filter glass, an optical glass in which CuO is added to a fluorinated glass is developed and used so as to selectively absorb wavelengths in the near-infrared region and have high weather resistance. The compositions of these glasses are disclosed in Patent Documents 1 to 4.

Japanese Unexamined Patent Publication No. 1-219037 Japanese Unexamined Patent Publication No. 2004-83290 Japanese Unexamined Patent Publication No. 2004-137100 International Publication No. 2015/156163

Cameras and the like using a solid-state image sensor are becoming smaller and thinner. Along with this, imaging devices and their on-board devices are also required to be smaller and thinner. When thinning a near-infrared cut filter glass in which CuO is added to a fluorinated glass, it is necessary to increase the concentration of the Cu component that affects the optical characteristics. However, when the concentration of the Cu component in the glass is increased, the optical characteristics on the near infrared side are desired, but there is a problem that the transmittance of light in the visible region is lowered.

Among the Cu components, Cu ²⁺ has the effect of cutting near infrared rays, but Cu ⁺ has the effect of weakening the intensity of blue (selectively absorbing only light of blue wavelength in visible light). be. When used in an image sensor application, if the transmittance of only a specific wavelength of visible light is low, the effect on the captured image is large, which is not preferable. Patent Document 4 ^{studies a method of suppressing the amount of Cu +} , but it is difficult to completely suppress the amount of ^{Cu +} even if the redox of the molten glass is strictly controlled.

The present invention provides a near-infrared cut filter glass having a high visible light transmittance even if the concentration of Cu component in the filter glass increases due to the thinning of the filter glass. With the goal.

As a result of diligent studies, the present inventor has determined that the filter glass containing P and Cu as essential components contains at least one selected from Cl, Br and I, and the filter glass contains crystals. , It has been found that a near-infrared cut filter glass having excellent devitrification resistance and optical characteristics can be obtained.

The near-infrared cut filter glass of the present invention essentially contains P and Cu as cation components, and at least one selected from Cl, Br and I as an anion component, and the Cu content is 0 in% cation. It is characterized in that it is 5 to 25% and contains crystals.

In the near-infrared cut filter glass of the present invention, the content of at least one selected from Cl, Br and I is preferably 0.01 to 20% in% anion.

Further, in the near-infrared cut filter glass of the present invention, it is preferable that the crystal contains at least one crystal selected from CuCl, CuBr and CuI.

Further, in the near-infrared cut filter glass of the present invention, it is preferable that Ag is contained as a cation component and the content of Ag is 0.01 to 5% in terms of cation%.

Further, in the near-infrared cut filter glass of the present invention, P ₂ O ₅ : 35 to 75% is displayed in terms of mass% based on oxides.
Al ₂ O ₃ : 5 to 15%
R ₂ O: 3 to 30% (However, R ₂ O represents the total amount of _{Li 2} O, Na ₂ O and K _{2 O)}
R'O: 3 to 35% (However, R'O represents the total amount of MgO, CaO, SrO, BaO, and ZnO)
CuO: 0.5-20%
Is preferably contained.

Further, the near-infrared cut filter glass of the present invention is
Cation% P ⁵⁺ : 20-50%
Al ³⁺ : 5 to 20%
R ⁺ : 15-40% (where R ⁺ represents the total amount of Li ⁺ , Na ⁺ , and K ⁺⁾
R ^'2+: 5~30% (however, R' ²⁺ is ^{Mg 2+, Ca 2+, Sr 2+} , represents the total amount of ^{Ba 2+,} and ^{Zn 2+.)}
Total amount of Cu ²⁺ and Cu ⁺ : 0.5 to 25%
F ⁻ : 10 to 70% with% anion
Is preferably contained.

Further, the near-infrared cut filter glass of the present invention preferably has a light transmittance of 80% or more at a wavelength of 450 nm.

According to the present invention, it is possible to obtain a near-infrared cut filter glass having high visible light transmittance and low near-infrared light transmittance and excellent optical characteristics.

The near-infrared cut filter glass of the present invention (hereinafter, also simply referred to as “filter glass”) indispensably contains P and Cu as a cation component, and contains at least one selected from Cl, Br and I as an anion component. However, it is a filter glass containing 0.5 to 25% of the Cu in a cation%, and is characterized by containing crystals in the filter glass.

That is, the filter glass of the present invention is composed of glass and crystals. In the filter glass of the present invention, the glass is an amorphous component and is mainly composed of the filter glass. Further, the crystal is preferably a crystal in which the components contained in the glass are precipitated in the glass as crystals. In the present specification, the content of each component indicates the content in the filter glass. Further, in the following description, the term "glass" simply means glass as an amorphous component in the filter glass.

P is a main component (glass-forming oxide) that forms glass, and is an essential component for enhancing the cuttability of the filter glass in the near infrared region. P is contained in the glass as, for example, P ^5+.

Further, Cu is an essential component for cutting near infrared rays. Cu is contained in the glass as, for example, Cu ²⁺ and Cu ^+. If the Cu content in the filter glass is less than 0.5%, the effect cannot be sufficiently obtained when the wall thickness of the filter glass is reduced, and if it exceeds 25%, the visible transmittance is lowered, which is preferable. No. The Cu content is preferably 0.5 to 19%, more preferably 0.6 to 18%, and even more preferably 0.7 to 17%. The Cu content ^{refers to the total amount of Cu 2+} , Cu ⁺ in the glass, and the Cu component in the crystal.

The filter glass of the present invention contains at least one selected from Cl, Br and I as an anion component. Two or more kinds of Cl, Br and I may be contained in combination. Cl, Br and I are contained in ^{the glass as Cl −} , Br ⁻ and I ^{−, respectively.} The content of Cl, Br and I in the filter glass is preferably 0.01 to 20%, which is the total amount of anion%. If the content of Cl, Br and I is less than 0.01%, crystals are difficult to precipitate, and if it exceeds 20%, the volatility becomes high and the veins in the glass may increase, which is not preferable. The total content of Cl, Br and I in the filter glass is preferably 0.01 to 15%, more preferably 0.02 to 10%.

Cl ⁻ , Br ⁻ , and I ⁻ react with ^{Cu + in} the glass ^{, Cl −} forms CuCl, Br ⁻ forms CuBr, and I ⁻ forms CuI. These components make it possible to sharply cut near-ultraviolet light in the obtained filter glass. Cl ⁻ , Br ⁻ , and I ⁻ can be appropriately selected according to the wavelength at which light in the near-ultraviolet region is desired to be sharply cut.

The crystal contained in the filter glass of the present invention preferably contains at least one crystal selected from CuCl, CuBr and CuI. That is, CuCl, CuBr, and CuI contained in the filter glass are preferably precipitated as crystals. Since at least one selected from CuCl, CuBr and CuI is precipitated in the crystalline state, the sharp cut property of light in the ultraviolet region can be enhanced.

The filter glass of the present invention preferably contains Ag as a cationic component. Ag binds to at least one selected from Cl, Br and I to precipitate silver halides (eg AgCl). In this case, AgCl acts as a crystal nucleus and has an effect of facilitating the precipitation of CuCl crystals. The content of Ag in the filter glass is preferably 0.01 to 5% as% cation. If it is less than 0.01%, the effect of precipitating crystals cannot be sufficiently obtained. On the other hand, if it exceeds 5%, Ag colloid is formed and the transmittance of visible light is lowered, which is not preferable.

Further, at least one crystal selected from CuCl, CuBr and CuI may be precipitated by precipitating or introducing a component that becomes a crystal nucleus other than silver halide into the filter glass.

The crystal component in the filter glass of the present invention is mainly composed of at least one selected from CuCl, CuBr and CuI, and a crystal nucleus or other crystals in which at least one selected from Ag and Cl, Br and I are bonded. It may contain a nucleus.

Next, the filter glass of the present invention will be described by taking as an example the filter glass of the two embodiments, that is, the filter glass of the first embodiment composed of the phosphoric acid glass and the crystal and the filter glass of the second embodiment composed of the phosphoric acid glass and the crystal. do.

<Filter glass of embodiment 1>
Filter glass according to the first embodiment of the present invention, _P 2 _O 5 mass% based on oxide: 35 to 75%
Al ₂ O ₃ : 5 to 15%
R ₂ O: 3 to 30% (However, R ₂ O represents the total amount of _{Li 2} O, Na ₂ O and K _{2 O)}
R'O: 3 to 35% (However, R'O represents the total amount of MgO, CaO, SrO, BaO, and ZnO)
CuO: 0.5-20%
Contains.

The filter glass of the first embodiment contains at least one selected from Cl, Br and I. The content and the content form of at least one selected from Cl, Br and I in the filter glass of the first embodiment are as described above. The reason why the content of each component constituting the filter glass of the first embodiment of the present invention is limited as described above will be described below. In the following description, the content "%" of the component contained in the filter glass of the first embodiment is the mass% based on the oxide unless otherwise specified.

P ₂ O ₅ is a main component (glass-forming oxide) that forms glass and is an essential component for improving the cuttability of the filter glass in the near-infrared region, but if it is less than 35%, the effect is sufficiently obtained. If it exceeds 75%, the glass becomes unstable, the weather resistance is lowered, and the residual amount of at least one selected from Cl, Br and I in the optical glass is lowered, and crystals are not sufficiently precipitated. Therefore, it is not preferable. The content of P ₂ O ₅ is preferably 38 to 73%, more preferably 40 to 72%.

Al ₂ O ₃ is a main component (glass-forming oxide) that forms glass and is an essential component for enhancing weather resistance, but if it is less than 5%, the effect cannot be sufficiently obtained, and 15% is used. If it exceeds the limit, the glass becomes unstable and the near-infrared ray blocking property of the filter glass deteriorates, which is not preferable. The content of Al ₂ O ₃ is preferably 5.5 to 12%, more preferably 6 to 10%.

R ₂ O (where R ₂ O represents the sum of Li ₂ O, Na ₂ O and K ₂ O) lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. It is a component for making the glass, but if it is less than 3%, the effect cannot be sufficiently obtained, and if it exceeds 30%, the glass becomes unstable, which is not preferable. The content of R ₂ O is preferably 5 to 28%, more preferably 6-25%. It should be _{noted that R 2} O means the total amount of Li ₂ O, Na ₂ O and K ₂ O, that is, Li ₂ O + Na ₂ O + K ₂ O. Further, R ₂ O is _{one kind or two or more kinds selected from Li 2} O, Na ₂ O and K ₂ O, and in the case of two or more kinds, any combination may be used.

Li ₂ O is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When Li ₂ O is contained, if it exceeds 15%, the glass becomes unstable, which is not preferable. The content of Li ₂ O is preferably 0 to 10%, more preferably 0 to 8%.

Na ₂ O is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When Na ₂ O is contained, if it exceeds 25%, the glass becomes unstable, which is not preferable. The content of Na ₂ O is preferably 0 to 22%, more preferably 0 to 20%.

K ₂ O is not an essential component, but is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, and the like. When K ₂ O is contained, if it exceeds 25%, the glass becomes unstable and the coefficient of thermal expansion becomes extremely large, which is not preferable. The K ₂ O content is preferably 0-20%, more preferably 0-15%.

R'O (where R'O represents the sum of MgO, CaO, SrO, BaO, and ZnO) lowers the melting temperature of the glass, lowers the liquidus temperature of the glass, and stabilizes the glass. It is an essential ingredient for making glass and increasing the strength of glass. If it is less than 3%, the effect cannot be sufficiently obtained, and if it exceeds 35%, the glass becomes unstable, the near-infrared cut property of the filter glass is lowered, the strength of the glass is lowered, and so on, which is not preferable. The content of R'O is preferably 3.5 to 32%, more preferably 4 to 30%. R'O means the total amount of MgO, CaO, SrO, BaO, and ZnO, that is, R'O is MgO + CaO + SrO + BaO + ZnO. Further, R'O is one kind or two or more kinds selected from MgO, CaO, SrO, BaO and ZnO, and in the case of two or more kinds, any combination may be used.

MgO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, increasing the strength of glass, and the like. However, MgO tends to make the glass unstable and easily devitrified, and it is preferable not to contain MgO especially when it is necessary to set a high Cu content. When MgO is contained, if it exceeds 5%, the glass becomes extremely unstable and the near-infrared cut property of the filter glass is lowered, which is not preferable. The content of MgO is preferably 0 to 3%, more preferably 0 to 2%.

CaO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, increasing the strength of the glass, and the like. When CaO is contained, if it exceeds 10%, the glass becomes unstable and easily devitrified, and the near-infrared cut property of the filter glass is lowered, which is not preferable. The CaO content is preferably 0 to 7%, more preferably 0 to 5%.

SrO is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When SrO is contained, if it exceeds 15%, the glass becomes unstable and easily devitrified, and the near-infrared cut property of the filter glass is lowered, which is not preferable. The content of SrO is preferably 0 to 12%, more preferably 0 to 10%.

Although BaO is not an essential component, it is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When BaO is contained, if it exceeds 30%, the glass becomes unstable and easily devitrified, and the near-infrared cut property of the filter glass is lowered, which is not preferable. The content of BaO is preferably 0 to 27%, more preferably 0 to 25%.

Although ZnO is not an essential component, it has effects such as lowering the melting temperature of glass, lowering the liquidus temperature of glass, and increasing the chemical durability of glass. When ZnO is contained, if it exceeds 10%, the glass becomes unstable and easily devitrified, and the solubility of the glass deteriorates, which is not preferable. The ZnO content is preferably 0 to 8%, more preferably 0 to 5%.

CuO is an essential component for cutting near infrared rays. If the content of CuO in the filter glass is less than 0.5%, the effect cannot be sufficiently obtained when the wall thickness of the filter glass is reduced, and if it exceeds 20%, the visible transmittance of the filter glass decreases. Therefore, it is not preferable. The CuO content is preferably 0.8 to 19%, more preferably 1.0 to 18%.

The content of Cu in the cation% of the filter glass of the first embodiment is 0.5 to 25% as described above, and the preferable content is also as described above. When the above Cl, Br, and I form CuCl, CuBr, and CuI, respectively, the cation% of Cu in the filter glass is the total content of the Cu component and other Cu components in the copper halide. be.

The filter glass of the first embodiment may contain 0 to 3% _{of Sb 2} O _{3 as an optional component.} Although Sb ₂ O ₃ is not an essential component, it has the effect of increasing the visible range transmittance of the filter glass. When Sb ₂ O ₃ is contained, if it exceeds 3%, the stability of the glass is lowered, which is not preferable. The content of Sb ₂ O ₃ is preferably 0 to 2.5%, more preferably 0 to 2%.

The filter glass of the first embodiment can further contain other components normally contained in the phosphoric acid glass such _{as SiO 2} , SO ₃ , B ₂ O _{3 as optional components as long as the effects of the present invention are not impaired.} The total content of these components is preferably 3% or less.

Further, the filter glass of the first embodiment contains crystals as described above, and preferably contains at least one crystal selected from CuCl, CuBr and CuI. The content of the crystal component in the filter glass of the first embodiment is preferably in the same range as the above as the crystallinity of the filter glass.

The filter glass of the first embodiment may further contain Ag as an optional component. The Ag content and the content form in the filter glass of the first embodiment are as described above.

<Filter glass of embodiment 2>
The filter glass of the second embodiment is
Cation% P ⁵⁺ : 20-50%
Al ³⁺ : 5 to 20%
R ⁺ : 15-40% (where R ⁺ represents the total amount of Li ⁺ , Na ⁺ , and K ⁺⁾
R ^'2+: 5~30% (however, R' ²⁺ is ^{Mg 2+, Ca 2+, Sr 2+} , represents the total amount of ^{Ba 2+,} and ^{Zn 2+.)}
Total amount of Cu ²⁺ and Cu ⁺ : 0.5 to 25%
F ⁻ : 10 to 70% with% anion
It is characterized by containing.

In the present specification, "cation%" and "anion%" are units as follows. First, the constituent components of the filter glass are divided into a cation component and an anion component. The "cation%" is a unit in which the content of each cation component is expressed as a percentage when the total content of all cation components contained in the filter glass is 100 mol%. "Anion%" is a unit in which the content of each anion component is expressed as a percentage when the total content of all anion components contained in the filter glass is 100 mol%.

The filter glass of the second embodiment ^{contains O 2-} as an anion component in addition to ^{F −} , and contains at least one selected from ^{Cl −} , Br ⁻ and I ^{−. The content of O 2-} in the filter glass of the second embodiment is as follows, and the content and the content form of at least one selected from ^{Cl −} , Br ⁻ and I ^{− are as described above.}

The reason why the content (displayed in% cation and% anion) of each component constituting the filter glass of the second embodiment of the present invention is limited as described above will be described below. In the following description, the content “%” of the component contained in the filter glass of the second embodiment is cation% for the cation component and anion% for the anion component unless otherwise specified.

(Cation component)
P ⁵⁺ is a main component (glass-forming oxide) that forms glass and is an essential component for improving the cuttability of the filter glass in the near-infrared region, but if it is less than 20%, the effect cannot be sufficiently obtained. If it exceeds 50%, the glass becomes unstable and the weather resistance is lowered, which is not preferable. The content of P ⁵⁺ is preferably 20 to 48%, more preferably 21 to 46%, still more preferably 22 to 44%.

Al ³⁺ is a main component (glass-forming oxide) that forms glass and is an essential component for enhancing weather resistance, but if it is less than 5%, the effect cannot be sufficiently obtained, and if it exceeds 20%, the effect cannot be sufficiently obtained. It is not preferable because the glass becomes unstable and the near-infrared ray blocking property of the filter glass is lowered. The content of Al ³⁺ is preferably 6 to 18%, more preferably 6.5 to 15%, and even more preferably 7 to 13%.

R ⁺ (where R ⁺ represents the sum of Li ⁺ , Na ⁺ and K ⁺ ) is used to lower the melting temperature of the glass, lower the liquidus temperature of the glass, stabilize the glass, etc. However, if it is less than 15%, the effect cannot be sufficiently obtained, and if it exceeds 40%, the glass becomes unstable, which is not preferable. The content of R ⁺ is preferably 15 to 38%, more preferably 16 to 37%, still more preferably 17 to 36%. Note that R ⁺ means the ^{total amount of Li +} , Na ⁺ , and K ⁺ , that is, Li ⁺ + Na ⁺ + K ⁺ . Further, R ⁺ is ^{one kind or two or more kinds selected from Li +} , Na ⁺ and K ⁺ , and in the case of two or more kinds, any combination may be used.

Li ⁺ is an essential component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, and the like. If it is less than 5%, the effect cannot be sufficiently obtained, and if it exceeds 40%, the glass becomes unstable, which is not preferable. The Li ⁺ content is preferably 8 to 38%, more preferably 10 to 35%, and even more preferably 15 to 30%.

Na ⁺ is not an essential component, but is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When Na ⁺ is contained, the effect cannot be sufficiently obtained if it is less than 5%, and if it exceeds 40%, the glass becomes unstable, which is not preferable. The Na ⁺ content is preferably 5 to 35%, more preferably 6 to 30%.

K ⁺ is not an essential component, but is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, and the like. When K ⁺ is contained, the effect cannot be sufficiently obtained if it is less than 0.1%, and if it exceeds 30%, the glass becomes unstable, which is not preferable. The content of K ⁺ is preferably 0.5 to 25%, more preferably 0.5 to 20%.

^{R'2 +} (where ^{R'2 +} represents the ^{sum of Mg 2+} , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Zn ²⁺ ) lowers the melting temperature of the glass and lowers the liquidus temperature of the glass. It is an essential ingredient for lowering, stabilizing glass, and increasing the strength of glass. If it is less than 5%, the effect cannot be sufficiently obtained, and if it exceeds 30%, the glass becomes unstable, the near-infrared ray cutting property of the filter glass is lowered, the strength of the glass is lowered, and so on, which is not preferable. ^{The content of R'2 +} is preferably 5 to 28%, more preferably 7 to 25%, still more preferably 9 to 23%. Incidentally, R ^{'2+ is, Mg 2+, Ca 2+, Sr} 2+, Ba 2+, and the total amount of ^{Zn 2+, i.e.,} refers to a ^{Mg 2+ + Ca 2+ + Sr 2+} + Ba 2+ + Zn 2+. Also, R ^{'2+ is, Mg 2+, Ca 2+, Sr} 2+, is one or more selected from ^{Ba 2+} and ^{Zn 2+,} the case of two or more may be any combination.

Mg ²⁺ is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, increasing the strength of glass, and the like. However, Mg ²⁺ tends to make the glass unstable and easily devitrified. When Mg ²⁺ is contained, the effect cannot be sufficiently obtained if it is less than 1%, and if it exceeds 30%, the glass is extremely unstable. This is not preferable because the melting temperature of the glass rises. The content of Mg ²⁺ is preferably 1 to 25%, more preferably 1 to 20%.

Although Ca ²⁺ is not an essential component, it is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing glass, increasing the strength of glass, and the like. When Ca ²⁺ is contained, the effect cannot be sufficiently obtained if it is less than 1%, and if it exceeds 30%, the glass becomes unstable and easily devitrified, which is not preferable. The Ca ²⁺ content is preferably 1 to 25%, more preferably 1 to 20%.

Although Sr ²⁺ is not an essential component, it is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When Sr ²⁺ is contained, the effect is not sufficiently obtained if it is less than 1%, and if it exceeds 30%, the glass becomes unstable and easily devitrified, which is not preferable because the strength of the glass decreases. The content of Sr ²⁺ is preferably 1 to 25%, more preferably 1 to 20%.

Although Ba ²⁺ is not an essential component, it is a component for lowering the melting temperature of glass, lowering the liquidus temperature of glass, stabilizing the glass, and the like. When Ba ²⁺ is contained, the effect is not sufficiently obtained if it is less than 0.1%, and if it exceeds 30%, the glass becomes unstable and easily devitrified, which is not preferable because the strength of the glass decreases. The content of Ba ²⁺ is preferably 1 to 25%, more preferably 1 to 20%.

Although Zn ²⁺ is not an essential component, it has effects such as lowering the melting temperature of glass, lowering the liquidus temperature of glass, and increasing the chemical durability of glass. When Zn ²⁺ is contained, the effect cannot be sufficiently obtained if it is less than 1%, and if it exceeds 30%, the glass becomes unstable and easily devitrified, and the solubility of the glass deteriorates, which is not preferable. The content of Zn ²⁺ is preferably 1 to 25%, more preferably 1 to 20%.

The content of Cu as a cation component in the filter glass of the second embodiment, that ^{is, the total content of Cu 2+} and Cu ^{+ is} the total amount of the Cu component and other Cu components in the copper halide. Specifically, the Cu content is 0.5 to 25% as described above, and the preferable content is also as described above.

Cu ²⁺ is an essential component for cutting near infrared rays, and the content is preferably 0.1% or more and less than 25%. If the content is less than 0.1%, the effect cannot be sufficiently obtained when the wall thickness of the filter glass is thinned, and if it is 25% or more, the visible transmittance of the filter glass is lowered. It is not preferable because it cannot contain ^{Cu +.} The content of Cu ²⁺ is preferably 0.2 to 24%, more preferably 0.3 to 23%, and even more preferably 0.4 to 22%.

Cu ⁺ reacts with Cl, Br, and I and precipitates as copper halide crystals, whereby the effect of sharply cutting ultraviolet rays can be imparted to the filter glass. The Cu ⁺ content is preferably 0.1 to 15%. If the content is less than 0.1%, the effect cannot be sufficiently obtained, and if it exceeds 15%, the intensity of the blue color of the filter glass is weakened, which is not preferable. The content of Cu ⁺ is preferably 0.2 to 13%, more preferably 0.3 to 12%, and even more preferably 0.4 to 11%.

The filter glass of the second embodiment may contain 0 to 1% ^{of Sb 3+ as an arbitrary cationic component.} Although Sb ³⁺ is not an essential component, it has the effect of increasing the visible range transmittance of the filter glass. When Sb ³⁺ is contained, if it exceeds 1%, the stability of the glass is lowered, which is not preferable. The content of Sb ³⁺ is preferably 0.01 to 0.8%, more preferably 0.05 to 0.5%, and even more preferably 0.1 to 0.3%.

The filter glass of the second embodiment can further contain, as an arbitrary cation component, other components such as Si and B usually contained in the borosilicate glass as long as the effects of the present invention are not impaired. The total content of these components is preferably 5% or less.

(Anion component)
^O2- is an essential component for reducing the ultraviolet transmittance in order to stabilize the glass, increase the visible range transmittance of the filter glass, enhance the mechanical properties such as strength, hardness and elastic modulus. The content is preferably 30 to 90%. If ^{the content of O 2-} is less than 30%, the effect cannot be sufficiently obtained, and if it exceeds 90%, the glass becomes unstable and the weather resistance is lowered, which is not preferable. The content of O ^2- is more preferably 30 to 80%, still more preferably 30 to 75%.

F ⁻ is an essential component for improving weather resistance in order to stabilize the glass, but if it is less than 10%, the effect cannot be sufficiently obtained, and if it exceeds 70%, the visible transmittance of the filter glass is high. It is not preferable because there is a risk that the mechanical properties such as strength, hardness and elastic modulus will decrease, and the volatility will increase and the veins will increase. The content of F ⁻ is preferably 10 to 50%, more preferably 13 to 40%.

Since the filter glass of the second embodiment of the present invention contains the F component indispensably, it has excellent weather resistance. Specifically, it is possible to suppress deterioration of the surface of the filter glass and decrease in transmittance due to the reaction with moisture in the atmosphere. For the evaluation of weather resistance, for example, an optically polished filter glass sample is held in a high-temperature and high-humidity tank at 65 ° C. and a relative temperature of 90% for 1000 hours using a high-temperature and high-humidity tank. Then, the burnt state on the surface of the filter glass can be visually observed and evaluated. It is also possible to compare and evaluate the transmittance of the filter glass before it is put into the high temperature and high humidity tank and the transmittance of the filter glass after holding it in the high temperature and high humidity tank for 1000 hours.

The filter glass of the second embodiment can further contain, as an arbitrary anionic component, other components such as S usually contained in the borosilicate glass as long as the effects of the present invention are not impaired. The total content of these components is preferably 5% or less.

Further, the filter glass of the second embodiment contains crystals as described above, and preferably contains at least one crystal selected from CuCl, CuBr and CuI. The content of the crystal component in the filter glass of the second embodiment is preferably in the same range as the above as the crystallinity of the filter glass.

The filter glass of the second embodiment may further contain Ag as an arbitrary cationic component. The Ag content and the content form in the filter glass of the second embodiment are as described above.

Next, the content of other components that are optional components other than the above components, which are common to the filter glass of the first embodiment and the filter glass of the second embodiment of the present invention, will be described. In addition, in this specification, "substantially not contained" means that it is not intentionally used as a raw material, and it is considered that it does not contain raw material components or unavoidable impurities mixed from the manufacturing process.

It is preferable that the filter glass of the present invention _{contains substantially none of PbO, As 2} O ₃ , V ₂ O ₅ , YbF ₃ , and GdF _3. PbO is a component that lowers the viscosity of glass and improves manufacturing workability. In addition, As ₂ O ₃ is a component that acts as an excellent clarifying agent capable of generating a clarifying gas in a wide temperature range. However, since PbO and As ₂ O ₃ are environmentally hazardous substances, it is desirable that they are not contained as much as possible. Since V ₂ O ₅ has absorption in the visible region, it is desirable that it is not contained as much as possible in the near-infrared cut filter glass for a solid-state image sensor, which is required to have high visible region transmittance. Although YbF ₃ and GdF ₃ are components that stabilize glass, they are desirable to be contained as little as possible because the raw materials are relatively expensive and lead to cost increase.

In the filter glass of the present invention, a nitrate compound or a sulfate compound having cations forming the glass can be added as an oxidizing agent or a clarifying agent. The oxidant has the effect of improving the cuttability of near infrared rays by increasing the ratio ^{of Cu 2+} ions in the total amount of Cu in the filter glass. The amount of the nitrate compound or the sulfate compound added is preferably 0.5 to 10% by mass based on the external split addition with respect to the raw material mixture. If the amount added is less than 0.5% by mass, the effect of improving the transmittance is difficult to obtain, and if it exceeds 10% by mass, it tends to be difficult to form glass. It is more preferably 1 to 8% by mass, and even more preferably 3 to 6% by mass.

Nitrate compounds include Al (NO ₃ ) ₃ , LiNO ₃ , NaNO ₃ , KNO ₃ , Mg (NO ₃ ) ₂ , Ca (NO ₃ ) ₂ , Sr (NO ₃ ) ₂ , Ba (NO ₃ ) ₂ , Zn. There are (NO ₃ ) ₂ , Cu (NO ₃ ) _{2, and the} like. The sulfate _{compounds, Al 2 (SO 4) 3} · 16H 2 O, Li 2 SO 4, Na 2 SO 4, K 2 SO 4, MgSO 4, CaSO 4, SrSO 4, BaSO 4, ZnSO 4, CuSO 4 And so on.

Further, the filter glass of the present invention preferably has an average transmittance of 80% or more of light having a wavelength of 450 to 600 nm when the wall thickness is 0.03 to 0.3 mm. When it is set to 80% or more, light in the visible range can be sufficiently transmitted, and a clear image can be displayed when used in an imaging device.

Further, when the wall thickness of the filter glass of the present invention is 0.03 to 0.3 mm, the wavelength at which the transmittance is 50% is preferably 600 to 650 nm. Under such conditions, it is possible to realize desired optical characteristics in a sensor that is required to be thin. Further, when the wall thickness is 0.03 to 0.3 mm, the transmittance of light having a wavelength of 450 nm is 80%, so that a near-infrared cut filter having more excellent optical characteristics can be obtained.

The value of the transmittance was converted so as to be the value when the wall thickness was 0.03 to 0.3 mm. The conversion of the transmittance was performed using the following formula 1. _{Ti 1} is the internal transmittance of the measurement sample (data excluding the reflection loss on the front and back surfaces), t ₁ is the wall thickness (mm) of the measurement sample, _{Ti 2} is the converted transmittance, and t ₂ is the converted transmittance. , Refers to the wall thickness to be converted (0.03 to 0.3 mm in the case of the present invention).

Since the near-infrared cut filter glass of the present invention corresponds to the miniaturization and thinning of the image pickup device and the equipment mounted on the image pickup device, good spectral characteristics can be obtained even when the wall thickness of the filter glass is thin. The wall thickness of the filter glass is preferably 1 mm or less, more preferably 0.8 mm or less, still more preferably 0.6 mm or less, and most preferably 0.4 mm or less. The lower limit of the wall thickness of the filter glass is not particularly limited, but is preferably 0.03 mm or more, more preferably 0. It is 05 mm or more, more preferably 0.07 mm or more, and most preferably 0.1 mm or more.

The filter glass of the present invention may be formed into a predetermined shape, and then an optical thin film such as an antireflection film, an infrared cut film, an ultraviolet ray and an infrared cut film may be provided on the surface of the filter glass. These optical thin films are made of a single-layer film or a multilayer film, and can be formed by a known method such as a vapor deposition method or a sputtering method.

The near-infrared cut filter glass of the present invention can be produced as follows. First, the raw materials are weighed and mixed so that the obtained filter glass has the above composition range (mixing step). This raw material mixture is housed in a platinum crucible and melted by heating in an electric furnace at a temperature of 700 to 1300 ° C. (melting step). After sufficiently stirring and clarifying, it is cast in a mold to precipitate crystals (crystal precipitation step), and then cut and polished to form a flat plate having a predetermined wall thickness (molding step).

In the melting step of the above manufacturing method, in the filter glass composed of fluorinated glass and crystals, for example, in the filter glass of the second embodiment, the highest temperature of the glass during glass melting is set to 950 ° C. or lower, and the filter composed of phosphoric acid glass and crystals. In the glass, for example, the filter glass of the first embodiment, the temperature is preferably 1280 ° C. or lower. This is because if the highest temperature of the glass during glass melting exceeds the above temperature, the transmittance characteristics deteriorate, and in the futuric acid glass, the volatilization of fluorine is promoted and the glass becomes unstable. The temperature is more preferably 900 ° C. or lower, still more preferably 850 ° C. or lower in the borosilicate glass. In phosphoric acid glass, it is more preferably 1250 ° C. or lower, still more preferably 1200 ° C. or lower.

Further, if the temperature in the melting step becomes too low, problems such as devitrification during melting and a long time for melting down occur. Therefore, the borosilicate glass is preferably 700 ° C. or higher, more preferably 750 ° C. That is all. In phosphoric acid glass, it is more preferably 800 ° C. or higher, still more preferably 850 ° C. or higher. In the above method for producing filter glass, it is preferable that the glass component does not crystallize before the following crystal precipitation step, and therefore the temperature in the melting step is preferably in the above range.

The crystal precipitation step performed following the melting step is preferably carried out by slow cooling or slow cooling and heat treatment. The slow cooling is preferably performed on the borosilicate glass at a rate of 0.1 to 2 ° C./min until the temperature reaches 200 to 250 ° C. In phosphoric acid glass, it is preferable to carry out at a rate of 0.1 to 2 ° C./min until the temperature reaches 200 to 250 ° C.

When the crystal precipitation step is carried out by slow cooling and heat treatment, after slow cooling similar to the above slow cooling conditions, the temperature of the borosilicate glass is raised from the temperature after slow cooling to 400 to 600 ° C. It is preferable to carry out the heat treatment. Similarly, for phosphoric acid glass, it is preferable to carry out slow cooling in the same manner as the above-mentioned slow cooling conditions, and then perform heat treatment for raising the temperature from the temperature after slow cooling to 350 to 600 ° C.

In the above method for producing filter glass, crystals are precipitated in the glass in such a crystal precipitation step. The obtained filter glass of the present invention is a filter glass composed of an amorphous (glass) portion and a crystalline portion. In the crystal precipitation step, it is preferable to precipitate at least one crystal selected from CuCl, CuBr and CuI in the glass. ^{By precipitating the crystals of CuCl, CuBr, and CuI, the amount of Cu + in} the amorphous (glass) portion excluding the crystal portion can be reduced in the obtained filter glass, and the sharp cut effect of ultraviolet rays can be imparted. It is also preferable because it can be used.

Examples and comparative examples of the present invention are shown in Tables 1 to 3. Table 1 shows examples of filter glass related to phosphoric acid glass, Examples 1-1 and 1-2 are examples of the present invention, and Example 1-3 is a comparative example of the present invention. Tables 2 and 3 show examples of filter glass related to borosilicate glass, and Examples 2-1 and 2-4 to 2-8 are examples of the present invention, and Examples 2-2 and 2-3 Is a comparative example of the present invention.

[Making filter glass]
The raw materials are weighed and mixed so as to have the composition shown in Table 1 (displayed in mass% based on oxide) and the composition shown in Tables 2 and 3 (cation%, anion%), and placed in a platinum crucible having an internal volume of about 400 cc. After melting, clarifying, and stirring at a temperature of 800 to 1300 ° C. for 2 hours, the mixture was cast into a rectangular mold having a length of 50 mm, a width of 50 mm, and a height of 20 mm, which was preheated to about 300 to 500 ° C.

For the examples of the present invention (Example 1-1, Example 1-2, Example 2-1 and Examples 2-4 to 2-8), after casting into a rectangular mold, slow cooling or slow cooling is performed. And heat treatment (Example 1-1, Example 1-2: After holding at 460 ° C. for 1 hour, cooling to room temperature at 1 ° C./min, then holding at 480 ° C. for 1 hour, then cooling to room temperature at 1 ° C./min, Example 2-1: After holding at 360 ° C. for 1 hour, cooling to room temperature at 1 ° C./min, Example 2-4, Example 2-6 to Example 2-8: After holding at 360 ° C. for 1 hour, then 1 ° C./ Cool to room temperature in minutes, then hold at 410 ° C. for 2 hours, then cool to room temperature at 1 ° C./min, eg 2-5: Hold at 410 ° C. for 1 hour, then cool to room temperature at 1 ° C./min). rice field. For Comparative Examples (Example 1-3, Example 2-2, Example 2-3), slow cooling (Example 1-3: After holding at 460 ° C. for 1 hour, cooling to room temperature at 1 ° C./min, Example 2- 2. Example 2-3: After holding at 360 ° C. for 1 hour, cooling to room temperature at 1 ° C./min). In each example, a block-shaped filter glass having a length of 50 mm, a width of 50 mm, and a thickness of 20 mm was obtained. After grinding this filter glass, a glass plate polished to a desired thickness was used for evaluation.

The raw materials for each filter glass _{are H 3} PO ₄ and / or Al (PO ₃ ) ₃ in the case of ^{P 5+} _{, Al F 3} , Al (PO ₃ ) ₃ and / or Al ₂ O _{3 in} the case of ^{Al 3+.} the, in the case of Li ⁺ _LiF, a LiNO _3, Li 2 _{CO 3} and / or LiPO ₃ a, in the case of ^{Mg 2+} MgF ₂ and / or MgO and / or Mg _{(PO 3) 2,} the case of ^{Sr 2+} is SrF ₂ , SrCO ₃ and / or Sr (PO ₃ ) ₂ , BaF ₂ , BaCO ₃ and / or Ba (PO ₃ ) ₂ ^{for Ba 2+} , Na ⁺ for NaCl and / or NaBr and / or NaI and / Or NaF and / or Na (PO ₃ ), fluoride, carbonate and / or metaphosphate for ^{K +} , Ca ²⁺ , Zn ²⁺ , Sb ₂ O ₃ ^{for Sb 3+} , Cu ²⁺ In ^{the case of Cu +} , CuO, CuCl, and CuBr were used, respectively. In the case of ^{Ag +} _{, AgNO 3} was used.

[evaluation]
With respect to the glass plates obtained in each example, the presence or absence of crystal precipitation can be confirmed by a powder X-ray diffractometer, a transmission electron microscope (TEM: Transmission Electron Microscope), or the like. Further, the transmittance of light having a wavelength of 450 to 600 nm was measured by an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation, V570). For Examples 1-1 to 1-3, the transmittance (calculated based on the surface reflection of the glass plate) converted to a wall thickness of 0.3 mm was obtained. For Examples 2-1 to 2-8, the transmittance converted to a wall thickness of 0.05 mm (calculated based on the surface reflection of the glass plate) was obtained. Tables 1, 2 and 3 show the presence or absence of crystals, the average transmittance of light having a wavelength of 450 to 600 nm, and the transmittance of light having a wavelength of 450 nm. Table 1 shows ^{the content of Cu (total of Cu 2+} and Cu ⁺ ) in% cation and the content of Cl + Br + I in% anion.

In the examples of the present invention, the crystal-precipitated Examples 1-1, 1-2, 2-1 and 2-4 to 2-8 were able to realize higher transmittance than the comparative examples. There is. Further, since the transmittance at 450 nm also exceeds 80%, it is preferable because the visible region side close to the ultraviolet region can be sufficiently transmitted when used in an imaging device or the like.

The near-infrared cut filter glass of the present invention has a high transmittance of light in the visible region even when the content of Cu component is large due to the thinning of the plate. Extremely useful for filter applications.

Claims (6)

Essentially contains P and Cu as cation components,
Containing at least one selected from Cl, Br and I as an anion component,
The content of Cu is 0.5 to 25% in terms of cation% and contains crystals .
In mass% display based on oxides
P ₂ O ₅ : 35-75%
Al ₂ O ₃ : 5 to 15%
R ₂ O: 3 to 30% (However, R ₂ O represents the total amount of _{Li 2} O, Na ₂ O and K _{2 O)}
R'O: 3 to 35% (However, R'O represents the total amount of MgO, CaO, SrO, BaO, and ZnO)
CuO: 0.5-20%
A near-infrared cut filter glass characterized by containing. Essentially contains P and Cu as cation components,
Containing at least one selected from Cl, Br and I as an anion component,
The Cu content is 0.5 to 25% in terms of cation%, and
Contains crystals,
With% cation
P ⁵⁺ : 20-50%
Al ³⁺ : 5-20%
R ^＋ 15-40% (however, R ^＋ Is Li ^＋ , Na ^＋ , And K ^＋ Represents the total amount of. )
R' ²⁺ : 5 to 30% (however, R' ²⁺ Is Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , And Zn ²⁺ Represents the total amount of. )
Cu ²⁺ And Cu ^＋ Total amount: 0.5 to 25%
With% anion
F ⁻ : 10-70%
A near-infrared cut filter glass characterized by containing. The near-infrared cut filter glass according to claim 1 or 2 , wherein the content of at least one selected from Cl, Br and I is 0.01 to 20% in% anion. The near-infrared cut filter glass according to any one of claims 1 to 3, wherein the crystal contains at least one crystal selected from CuCl, CuBr and CuI. Contains Ag as a cation component,
The near-infrared cut filter glass according to any one of claims 1 to 4 , wherein the Ag content is 0.01 to 5% in terms of cation%. The near-infrared cut filter glass according to any one of claims 1 to 5 , wherein the transmittance of light having a wavelength of 450 nm is 80% or more.