JP7089887B2 - Optical glass - Google Patents

Description

The present invention relates to optical glass, and more specifically to optical glass having high thermal shock resistance.

Optical glass is used in the fields of various optical devices such as shooting devices such as digital cameras and video cameras, and image reproduction (projection) devices such as projectors and projection televisions, and these devices constitute an optical system. It is used in applications such as lenses and prisms.

Here, as an optical glass having an optical constant in the range of a refractive index (nd) of 1.47 to 1.54 and an Abbe number (νd) of 60 to 68, a glass as represented by Patent Documents 1 to 4 is used. The composition is known.

Japanese Unexamined Patent Publication No. 2001-089183 Japanese Unexamined Patent Publication No. 2002-02136 Japanese Patent Application Laid-Open No. 2002-356348 Japanese Patent Application Laid-Open No. 2003-341557

The optical glasses described in Patent Documents 1 to 4 have been mainly used for optical devices used in a substantially fixed state, such as cameras and projectors. However, in recent years, optical elements have come to be used in action cameras attached to displacement means such as drones, in-vehicle cameras and headlights attached to transport machines such as automobiles, which occur when falling / landing or driving. There is a growing demand for optical glass that can withstand more physical impact.

Further, an optical glass capable of withstanding such a physical impact has been sought after in applications used outdoors, for example, applications such as surveillance cameras. In particular, in these applications used outdoors, strong winds and flying objects generated by them hit the optical glass, causing a physical impact.

The present invention has been made in view of the above problems, and an object thereof is to have impact resistance while the refractive index ( _{nd) and Abbe number (ν d )} are within desired ranges. It is to obtain high optical glass.

As a result of intensive test and research to solve the above problems, the present inventors have obtained an optical glass having high impact resistance in an optical glass containing a SiO ₂ component, a B ₂ O ₃ component, and an alkali metal component. We have found that it is possible to obtain it, and have completed the present invention. Specifically, the present invention provides the following.

(1) By mass% based on oxides,
SiO ₂ component 30.0-80.0%,
B ₂ O ₃ component 1.0 to 30.0% and Rn ₂ O component (in the formula, Rn is at least one of Li, Na, K) 1.0 to 30.0%.
It has an optical constant with a refractive index (nd) in the range of 1.47 to 1.54 and an Abbe number (νd) in the range of 60 to 68.
An optical glass having a minimum height of 100 cm or more at which the optical glass is damaged when a 23.8 g steel ball is freely dropped onto the optical glass.

(2) The optical glass according to (1), which is used for an outdoor optical instrument or an optical instrument having a displacement means.

(3) The optical glass according to (1) or (2), which is used for surveillance cameras, action cameras, in-vehicle cameras or headlights.

According to the present invention, it is possible to obtain an optical glass having a refractive index ( _{nd) and an Abbe number (ν d )} within a desired range but which is not easily broken even when a strong impact is applied.

It is sectional drawing of the main part which shows the structure of the surveillance camera in which the optical glass of this invention is preferably used. It is a schematic cross-sectional view which shows the structure of the optical system of the action camera and the vehicle-mounted camera in which the optical glass of this invention is preferably used. It is a schematic cross-sectional view which shows the structure of the headlight for a transport aircraft in which the optical glass of this invention is preferably used.

The optical glass of the present invention has a SiO ₂ component of 30.0 to 80.0%, a B ₂ O ₃ component of 1.0 to 30.0%, and an Rn ₂ O component (in the formula) in terms of mass% based on the oxide. , Rn is at least one of Li, Na, and K) is contained in an amount of 1.0 to 30.0%, a refractive index (nd) is 1.47 to 1.54, and an abbreviation number (νd) is 60 to 68. It has an optical constant in the range of 100 cm or more, and the minimum height at which the optical glass is damaged when a 23.8 g steel ball is freely dropped onto the optical glass is 100 cm or more. According to the present invention, an optical glass having high impact resistance can be obtained in an optical glass containing a SiO ₂ component, a B ₂ O ₃ component, and an alkali metal component. Therefore, it is possible to obtain an optical glass that is not easily broken even if a strong impact is applied, while the refractive index ( _{nd) and the Abbe number (ν d )} are within desired ranges.

Hereinafter, embodiments of the optical glass of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. be able to. It should be noted that the description may be omitted as appropriate for the parts where the explanations are duplicated, but the gist of the invention is not limited.

≪Glass component≫
The composition range of each component constituting the optical glass of the present invention is described below. Unless otherwise specified in the present specification, the content of each component shall be expressed as a mass% of the total mass of the glass in the oxide equivalent composition. Here, the "oxide-equivalent composition" is based on the assumption that the oxides, composite salts, metal fluorides, etc. used as raw materials for the glass constituents of the present invention are all decomposed at the time of melting and changed to oxides. The composition is such that each component contained in the glass is described with the total mass of the produced oxide as 100% by mass.

<About essential ingredients and optional ingredients>
The SiO ₂ component is an essential component that is indispensable as a glass-forming oxide, and is a component that can enhance the chemical durability of glass.
In particular, by containing 30.0% or more of the SiO ₂ component, the coloring of the glass can be reduced, the devitrification resistance can be enhanced, and the chemical durability and the impact resistance can be enhanced. Therefore, the content of the SiO ₂ component is preferably 30.0%, more preferably 40.0%, further preferably 46.0%, still more preferably 50.0%, still more preferably 55.0%, and further. The lower limit is preferably 60.0%.
On the other hand, by setting the content of the SiO ₂ component to 80.0% or less, it is possible to suppress an increase in the glass transition point and a bending point and suppress a decrease in the refractive index. Therefore, the content of the SiO ₂ component is preferably 80.0%, more preferably 78.0%, further preferably 74.0%, still more preferably 70.0%, still more preferably 65.0%. And.

The B ₂ O ₃ component is an essential component that is indispensable as a glass-forming oxide, and is a component that reduces the melt viscosity to obtain a homogeneous glass.
In particular, by containing 1.0% or _more of the B2O3 component _, the devitrification resistance of the glass can be enhanced and the dispersion of the glass can be reduced. Therefore, the content of the _B2O3 component is preferably 1.0%, _more preferably 3.0%, still more preferably 6.0%, still more preferably 10.0%, still more preferably 14.0%. Is the lower limit.
On the other hand, by setting the content of the B ₂ O ₃ component to 30.0% or less, a higher refractive index can be easily obtained, and deterioration of chemical durability and impact resistance can be suppressed. Therefore, the content of the _B2O3 component is preferably 30.0%, _more preferably 25.0%, still more preferably 22.0%, still more preferably 19.0%.

The total amount of the Rn ₂ O component (in the formula, Rn is one or more selected from the group consisting of Li, Na, and K) is preferably 1.0 to 30.0%.
In particular, by setting the total amount to 1.0% or more, the glass transition point and the yield point can be lowered, and the meltability at the time of glass production can be improved. Therefore, the mass sum of the Rn ₂ O components is preferably 1.0%, more preferably 5.0%, still more preferably 8.0%, still more preferably 11.0%, still more preferably 12.5%. The lower limit.
On the other hand, by setting the total amount to 30.0% or less, the refractive index of the glass can hardly be lowered, the chemical durability of the glass can be improved, and the devitrification resistance can be improved. Therefore, the mass sum of the Rn ₂ O components is preferably 30.0%, more preferably 26.0%, still more preferably 22.0%, still more preferably 18.0%, still more preferably 16.0%. The upper limit.

When the Li ₂ O component is contained in an amount of more than 0%, the meltability of the glass can be improved, the glass transition point can be lowered, and the formability at the time of press molding can be improved. Therefore, the lower limit of the content of the Li ₂ O component is preferably more than 0%, more preferably 2.0%, still more preferably 3.0%, still more preferably 4.0%, still more preferably 5.5%. May be.
On the other hand, by reducing the content of the Li ₂ O component to 20.0% or less, it is possible to make it difficult to lower the refractive index of the glass, improve the chemical durability of the glass, and improve the devitrification resistance. Be enhanced. Therefore, the content of the Li ₂ O component is preferably 20.0%, more preferably 15.0%, still more preferably 11.0%, still more preferably 8.0%.

The Na ₂ O component is an optional component that can improve the meltability of the glass, increase the devitrification resistance of the glass, and lower the glass transition point when the content exceeds 0%.
On the other hand, by setting the content of the Na ₂ O component to 15.0% or less, the refractive index of the glass can hardly be lowered and the chemical durability of the glass can be improved. Therefore, the content of the Na ₂ O component is preferably 15.0%, more preferably 10.0%, still more preferably 7.0%, still more preferably 4.0%.

_The K2O component is an optional component that can improve the meltability of the glass, increase the devitrification resistance of the glass, and lower the glass transition point when the content exceeds 0%. Therefore, the content of the K2O component may be preferably _more than 0%, more preferably 2.0%, still more preferably 6.6% as the lower limit.
_On the other hand, by setting the content of the K2O component to 25.0% or less, the refractive index of the glass can hardly be lowered and the chemical durability of the glass can be improved. Therefore, the content of the K2O component is preferably 25.0%, _more preferably 23.0%, still more preferably 20.0%, still more preferably 17.0%, still more preferably 14.0%. More preferably, the upper limit is 9.0%.

The Al ₂ O ₃ component is an optional component that enhances the chemical durability of the glass, suppresses the phase separation of the glass, and enhances the impact resistance and the devitrification resistance when the content exceeds 0%. Therefore, the content of the Al ₂ O ₃ component is preferably more than 0%, more preferably 1.0%, still more preferably 2.0%, still more preferably 3.0%, still more preferably 5.0%. It may be the lower limit.
On the other hand, by reducing the content of the Al ₂ O ₃ component to 23.0% or less, the decrease in the devitrification resistance of the glass due to the excessive content thereof can be suppressed, the increase in the yield point of the glass can be suppressed, and the increase in the yield point of the glass can be suppressed. , The viscosity at the time of forming glass can be lowered to facilitate press forming. Therefore, the content of the Al ₂ O ₃ component is preferably 23.0%, more preferably 19.0%, still more preferably 15.0%, still more preferably 10.0%, still more preferably 9.0%. Is the upper limit.

The total amount of the SiO ₂ component, the B ₂ O ₃ component and the Al ₂ O ₃ component is preferably 50.0% or more. As a result, it is possible to obtain a low yield point and viscosity having a desired refractive index and Abbe number and suitable for press molding, and to obtain excellent chemical durability, devitrification resistance, and impact resistance. Therefore, the sum of masses (SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ) is preferably 50.0%, more preferably 60.0%, still more preferably 68.0%, still more preferably 75.0%, and further. The lower limit is preferably 83.0%. On the other hand, the total amount may be preferably up to 98.0%, more preferably 94.0%, still more preferably 90.0%.

When the TiO ₂ component is contained in excess of 0%, the coloration due to solarization of the glass is reduced, the chemical durability is improved, the refractive index of the glass is high, the Abbe number is adjusted low, and the devitrification resistance is reduced. It is an optional ingredient that can enhance the sex. Therefore, the content of the TiO ₂ component may be preferably more than 0%, more preferably 0.01%, still more preferably 0.05%, still more preferably 0.10% as the lower limit.
On the other hand, by setting the content of TiO ₂ to 10.0% or less, the coloring of the glass can be reduced, the visible light transmittance can be increased, and the decrease in the Abbe number can be suppressed. Therefore, the content of the TiO ₂ component is preferably 10.0%, more preferably 5.0%, still more preferably 3.0%, still more preferably 1.0%.

The Nb ₂ O ₅ component and the WO ₃ component are optional components that can increase the refractive index of the glass and enhance the devitrification resistance when the content exceeds 0%. The WO ₃ component is also a component that can lower the glass transition point.
On the other hand, by reducing the contents of the Nb ₂ O ₅ component and the WO ₃ component to 10.0% or less, the coloring of the glass can be reduced, the visible light transmittance can be increased, and the decrease in the Abbe number can be suppressed. Be done. Therefore, the contents of the Nb ₂ O ₅ component and the WO ₃ component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1.0%, respectively. Less than.

When the ZnO component is contained in an amount of more than 0%, the glass transition point and the yield point can be lowered, the viscosity at the time of molding can be adjusted to be low, and the chemical durability can be enhanced. Therefore, the content of the ZnO component may be preferably more than 0%, more preferably 0.1%, and even more preferably 0.5% as the lower limit.
On the other hand, by setting the content of the ZnO component to 15.0% or less, the decrease in devitrification resistance can be suppressed. Therefore, the content of the ZnO component is preferably 15.0%, more preferably 10.0%, still more preferably 6.0%, still more preferably 4.0%.

The MgO component, CaO component, SrO component and BaO component are optional components that can enhance the meltability of the glass raw material and the devitrification resistance of the glass when the content exceeds 0%.
On the other hand, by setting the content of each of the MgO component, CaO component, SrO component and BaO component to 10.0% or less, the refractive index is lowered and the devitrification resistance is lowered due to the excessive content of these components. Can be suppressed. Therefore, the contents of the MgO component, the CaO component, the SrO component and the BaO component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1. It shall be less than 0%.

The total content (sum of mass) of the RO components (in the formula, R is one or more selected from the group consisting of Mg, Ca, Sr, and Ba) is preferably 12.0% or less. As a result, it is possible to suppress a decrease in the refractive index and a decrease in the devitrification resistance of the glass due to the excessive inclusion of the RO component. Therefore, the mass sum of the RO components is preferably 12.0% or less, more preferably less than 10.0%, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1.0. It shall be less than%.

The La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are optional components that can increase the refractive index of the glass and increase the Abbe number when the content exceeds 0%. ..
On the other hand, by reducing the content of each of the La ₂ O ₃ component, Gd ₂ O ₃ component, Y ₂ O ₃ component and Yb ₂ O ₃ component to 10.0% or less, the refractive index can be increased more than necessary. It can be suppressed and the devitrification resistance of the glass can be increased. Therefore, the contents of the La ₂ O ₃ component, the Gd ₂ O ₃ component, the Y ₂ O ₃ component, and the Yb ₂ O ₃ component are preferably 10.0% or less, more preferably less than 5.0%, and further preferably. Is less than 3.0%, more preferably less than 1.0%.

The sum (mass sum) of the contents of the Ln ₂ O ₃ component (in the formula, Ln is one or more selected from the group consisting of La, Gd, Y, and Yb) is preferably 10.0% or less.
By setting this sum to 10.0% or less, it is possible to suppress an increase in the refractive index more than necessary and to improve the devitrification resistance of the glass. Therefore, the mass sum of the Ln ₂ O ₃ components is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.

The P ₂ O ₅ component is an optional component that can enhance the devitrification resistance of the glass when it is contained in excess of 0%.
_On the other hand, by setting the content of the _P2O5 component to 10.0% or less, it is possible to suppress a decrease in the chemical durability of the glass, particularly the water resistance. Therefore, the content of the P2O5 component is preferably 10.0% or less, _more preferably less than _5.0 %, still more preferably less than 3.0%, still more preferably less than 1.0%.

The GeO ₂ component is an optional component that can increase the refractive index of glass and improve the devitrification resistance when it is contained in an amount of more than 0%. However, since the raw material price of Geo ₂ is high, the material cost increases when the amount is large. Therefore, the content of the GeO ₂ component is preferably 10.0% or less, more preferably less than 5.0%, further preferably less than 3.0%, still more preferably less than 1.0%, and most preferably contained. do not do.

_The ZrO2 component is an optional component that can contribute to high refractive index and low dispersion of glass and enhance devitrification resistance of glass when it is contained in excess of 0%.
On the other hand, by setting the content of the ZrO ₂ component to 10.0% or less, it is possible to suppress a decrease in the devitrification resistance of the glass due to an excessive content of the ZrO ₂ component. Therefore, the content of the ZrO2 component is preferably 10.0% or less, _more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.

The Ta ₂ O ₅ component is an optional component that, when contained in excess of 0%, can increase the refractive index of the glass, increase the devitrification resistance, and increase the viscosity of the molten glass.
On the other hand, by reducing the content of the expensive Ta ₂ O ₅ component to 10.0% or less, the material cost of the glass is reduced, so that cheaper optical glass can be produced. Further, as a result, the melting temperature of the raw material is lowered, and the energy required for melting the raw material is reduced, so that the manufacturing cost of the optical glass can be reduced. Therefore, the content of the Ta ₂ O ₅ component is preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably less than 1.0%.

The Bi ₂ O ₃ component and the Te O ₂ component are optional components that can increase the refractive index and lower the glass transition point when the content exceeds 0%.
On the other hand, by setting the content of the Bi ₂ O ₃ component to 10.0% or less, the devitrification resistance of the glass can be enhanced, and the coloring of the glass can be reduced to increase the visible light transmittance.
Further, TeO ₂ has a problem that it can be alloyed with platinum when the glass raw material is melted in a platinum crucible or a melting tank in which a portion in contact with the molten glass is made of platinum.
Therefore, the contents of the Bi _{2O 3} component and the TeO ₂ component are preferably 10.0% or less, more preferably less than 5.0%, still more preferably less than 3.0%, still more preferably 1.0%, respectively. Less than.

The SnO ₂ component is an optional component that can reduce the oxidation of the molten glass to make it clear and increase the visible light transmittance of the glass when it is contained in an amount of more than 0%.
On the other hand, by setting the content of the SnO ₂ component to 3.0% or less, it is possible to reduce the coloring of the glass and the devitrification of the glass due to the reduction of the molten glass. Further, since the alloying of the SnO ₂ component and the melting equipment (particularly noble metal such as Pt) is reduced, the life of the melting equipment can be extended. Therefore, the content of the SnO ₂ component is preferably 3.0%, more preferably 1.0%, and even more preferably 0.5%.

The Sb ₂ O ₃ component is an optional component capable of defoaming the molten glass when it contains more than 0%.
On the other hand, if the content of the Sb ₂ O ₃ component is too large, the transmittance in the short wavelength region of the visible light region deteriorates. Therefore, the content of the Sb ₂ O ₃ component is preferably 2.0%, more preferably 1.0%, and even more preferably 0.5%.

The component that clarifies and defoams the glass is not limited to the above Sb ₂ O ₃ component, and a clarifying agent, a defoaming agent, or a combination thereof known in the field of glass production can be used.

<Ingredients that should not be included>
Next, components that should not be contained in the optical glass of the present invention and components that are not preferable to be contained will be described.

Other components can be added as needed within a range that does not impair the characteristics of the glass of the present invention. However, each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag and Mo, excluding Ti, Zr, Nb, W, La, Gd, Y, Yb and Lu, is used alone. Alternatively, even if it is compounded and contained in a small amount, the glass is colored and has a property of causing absorption at a specific wavelength in the visible region. ..

Further, since lead compounds such as PbO and arsenic compounds such as As ₂ O ₃ are components having a high environmental load, it is desirable that they are not substantially contained, that is, they are not contained at all except for unavoidable contamination.

Furthermore, each component of Th, Cd, Tl, Os, Be, and Se has tended to refrain from being used as a harmful chemical substance in recent years, and is used not only in the glass manufacturing process but also in the processing process and disposal after commercialization. Environmental measures are required up to this point. Therefore, when the environmental impact is emphasized, it is preferable that these are not substantially contained.

≪Manufacturing method≫
The optical glass of the present invention is produced, for example, as follows. That is, raw materials such as oxides, carbonates, nitrates and hydroxides are uniformly mixed so that each component is within a predetermined content range, and the prepared mixture is put into a platinum crucible to melt the glass composition. It is produced by melting in an electric furnace in a temperature range of 1200 to 1500 ° C. for 2 to 4 hours depending on the degree of difficulty, stirring and homogenizing, lowering the temperature to an appropriate temperature, casting into a mold, and slowly cooling.

≪Physical characteristics≫
The optical glass of the present invention preferably has a high Abbe number (low dispersion). In particular, the Abbe number (ν _d ) of the optical glass of the present invention is preferably 60 as the lower limit, preferably 68, and more preferably 65 as the upper limit. Having such a low dispersion reduces the focus shift (chromatic aberration) due to the wavelength of light even with a single lens. Therefore, for example, when this optical glass is used for a camera, it is possible to shoot at a wider angle. It is possible to do. In addition, by having such a low dispersion, high imaging characteristics and the like can be achieved, for example, when combined with an optical element having a high dispersion (low Abbe number).

Further, the refractive index ( _nd ) of the optical glass of the present invention is preferably 1.47, more preferably 1.48 as the lower limit. The upper limit of the refractive index may be preferably 1.54, more preferably 1.53.

The optical glass of the present invention can reduce the size of the optical system while achieving such high imaging characteristics, and even in that case, it is a glass having high impact resistance.
In particular, the optical glass of the present invention is a rubber sheet made of natural rubber having a thickness of 5 mm and having a width of 50 mm × 50 mm or more and a steel ball of 23.8 g (diameter about 1.8 cm) made of SUJ-2. At least a part of the optical glass is cracked, chipped, cracked, etc. The minimum height (hereinafter referred to as "falling ball test result") that is damaged by the glass is 100 cm or more. As a result, damage to the optical element is reduced even if a strong wind or a flying object caused by the strong wind hits the optical glass. Further, the optical element is less likely to be damaged by the impact caused by dropping the device provided with the optical glass, the shaking generated when the device is displaced (moved), and the reaction when the displacement of the device is stopped by the displacement means. Therefore, even when the optical glass of the present invention is used for an outdoor optical device or a device having a displacement means, the life of the optical element or the device can be extended. Therefore, the lower limit of the ball drop test result of the optical glass of the present invention is preferably 100 cm, more preferably 105 cm, and most preferably 110 cm.

It is preferable that the optical glass of the present invention has a high visible light transmittance, particularly a light transmittance on the short wavelength side of visible light, and thus less coloring.
In particular, in the optical glass of the present invention, when expressed in terms of glass transmittance, the shortest wavelength (λ ₈₀ ) showing a spectral transmittance of 80% in a sample having a thickness of 10 mm is preferably 400 nm, more preferably 370 nm, and even more preferably. The upper limit is 350 nm.
Further, in the optical glass of the present invention, the shortest wavelength (λ ₅ ) showing a spectral transmittance of 5% in a sample having a thickness of 10 mm is preferably 360 nm, more preferably 340 nm, and further preferably 320 nm.
As a result, the absorption edge of the glass enters the ultraviolet region, and the transparency of the glass with respect to visible light is enhanced. Therefore, this optical glass can be preferably used for an optical element such as a lens that transmits light.

The optical glass of the present invention preferably has a small specific gravity. More specifically, the specific gravity of the optical glass of the present invention is preferably 4.50 [g / cm ³ ] or less. As a result, the weight of the optical element using optical glass is reduced, and the weight of the device equipped with the optical element is reduced. Therefore, especially when the device is dropped or the device is displaced (moved). It is possible to reduce the impact on the optical glass and its surrounding members due to the shaking of the device and the reaction when stopping the displacement of the device. Therefore, the specific gravity of the optical glass of the present invention is preferably 4.50, more preferably 4.30, still more preferably 4.00, still more preferably 3.80. The specific gravity of the optical glass of the present invention is often 2.00 or more, more specifically 2.20 or more.
The specific gravity of the optical glass of the present invention is measured based on the Japan Optical Glass Industry Association standard JOBIS05-1975 “Method for measuring the specific gravity of optical glass”.

The optical glass of the present invention preferably has a glass transition point (Tg) of 630 ° C. or lower. As a result, the glass softens at a lower temperature, so that the glass can be press-formed at a lower temperature. Further, it is possible to extend the life of the die by reducing the oxidation of the die used for press molding. Therefore, the glass transition point of the optical glass of the present invention is preferably 630 ° C, more preferably 600 ° C, and even more preferably 570 ° C. The lower limit of the glass transition point of the optical glass of the present invention is not particularly limited, but the glass transition point of the optical glass of the present invention is preferably 100 ° C., more preferably 200 ° C., and even more preferably 300 ° C. as the lower limit. good.

The optical glass of the present invention preferably has a yield point (At) of 700 ° C. or lower. The yield point is one of the indexes showing the softness of the glass as well as the glass transition point, and is an index showing a temperature close to the press forming temperature. Therefore, by using glass having a bending point of 700 ° C. or lower, press molding at a lower temperature becomes possible, so that press molding can be performed more easily. Therefore, the bending point of the optical glass of the present invention is preferably 700 ° C., more preferably 680 ° C., and most preferably 650 ° C. as the upper limit. The bending point of the optical glass of the present invention may be preferably 150 ° C., more preferably 250 ° C., and even more preferably 350 ° C. as the lower limit.

≪Use of optical glass≫
From the produced optical glass, a glass molded body can be produced by using, for example, a means for polishing or a means for mold press molding such as reheat press molding or precision press molding. That is, a glass molded body is produced by performing mechanical processing such as grinding and polishing on optical glass, or reheat press molding is performed on a preform produced from optical glass and then polishing is performed to form glass. It is possible to produce a glass molded body by performing precision press molding on a preform produced by producing a body, polishing, or a known preform formed by levitation molding or the like. The means for producing the glass molded body is not limited to these means.

As described above, the glass molded body formed from the optical glass of the present invention is useful for various optical elements and optical designs. Among them, it is particularly preferable to use the optical glass of the present invention for the use of the optical element in an outdoor optical device and the use of the optical element in an optical device having a displacement means.

<Use of optical elements in outdoor optical equipment>
Among these, applications of optical elements in outdoor optical equipment include surveillance cameras, action cameras, in-vehicle cameras, and headlights for transport aircraft. In these applications, strong winds and the resulting flying objects often exert a mechanical impact on the optics. By using the optical glass of the present invention for these purposes, it is possible to reduce damage to the optical element due to strong winds and flying objects caused by the strong wind without covering the optical element with a cover or an elastic body.

[Use of surveillance cameras]
Of these, the surveillance camera 1 is for attaching the camera device main body 11, the photographing lens barrel 12 attached to the camera device main body 11, and the photographing lens barrel 12 to the camera device main body 11, for example, as shown in FIG. It may have a mounting portion 13.

As shown in FIG. 1, the camera device main body 11 is housed in a housing 14 provided with an incident window 14a into which light guided from a photographing lens barrel 12 is incident, and an image pickup element (imaging element). It includes a substrate 16 having a CCD) 15. In addition, although not shown, a control unit, a power supply unit, and the like are provided inside the housing 14. The image pickup element 15 is arranged inside the housing 14 so that the optical axis C of the photographing lens barrel 12 attached to the incident window 14a side substantially coincides with the image pickup center O of the image pickup surface.

The photographing lens barrel 12 includes one or more photographing lenses, and a light flux from the subject is incident from the object point (subject) side. Then, the luminous flux incident from the photographing lens barrel 12 is imaged as an image of the subject on the image pickup surface of the image pickup element 15.

The photographing lens barrel 12 is composed of a desired optical system, and guides the light incident from the object point (subject) side to the image pickup element 15 of the camera apparatus main body 11 to form an image on the image pickup surface of the image pickup element 15. A male screw portion 12a screwed into a holder portion 132, which will be described later, is provided on the outer peripheral surface of the photographing lens barrel 12 on the camera device main body 11 side. When the photographing lens barrel 12 is attached to the camera device main body 11, the photographing lens barrel 12 is fixed to the holder portion 132.

The mounting portion 13 includes a base portion 131, a holder portion 132, a washer 133, and a stopper portion 134 that are sequentially arranged from the side of the camera device main body 11 toward the side of the photographing lens barrel 12. The mounting portion 13 is configured in a cylindrical shape in order to guide the light incident from the photographing lens barrel 12 to the side of the camera device main body 11.

The base portion 131 is formed of a cylindrical member having the image pickup center O of the image pickup element 15 provided on the camera device main body 11 as a central axis, and is integrally formed with the camera device main body 11 on the lens mounting side of the camera device main body 11. It is a thing.

The holder portion 132 is composed of a cylindrical member having a female screw portion 132a on the inner peripheral surface, and the male screw portion 12a of the photographing lens barrel 12 is screwed into the female screw portion 132a.

The washer (washer) 133 is composed of a hollow disk member, and is sandwiched between the stopper portion 134 and the holder portion 132, which will be described later, when the photographing lens barrel 12 is attached.

The stopper portion 134 is a member for fixing the holder portion 132 to the base portion 131, and a washer (washer) 133 is sandwiched between the holder portion 132 and the base portion 131 to fix them. Since the photographing lens barrel 12 can be fixed to the holder portion 132, the taking lens barrel 12 can be fixed to the camera device main body 11 by fixing the holder portion 132 to the base portion 131 by using the stopper portion 134. Can be fixed.

Such a surveillance camera 1 is mainly used for crime prevention in stores, banks, streets, and parking lots. However, unless a cover or the like is provided on the surface of the photographing lens barrel 12 of the surveillance camera 1 installed outdoors, the optical glass constituting the photographing lens barrel 12 is damaged by strong wind and flying objects generated by the strong wind. Often occurs.

Therefore, by using the optical glass of the present invention for the lens on the most subject (object point) side among the lenses constituting the photographing lens barrel 12 used for the surveillance camera 1, the photographing lens barrel due to strong wind or flying objects is used. It is possible to make the damage of 12 less likely to occur.

[Use of action camera]
An action camera is also called a wearable camera because of its characteristics, and is a helmet worn on the user's body via a mount, or a drone or an unmanned traveling device in which at least a part of the action camera is lifted or moved by being driven by a propeller or a motor. By attaching a camera to the camera and taking pictures, it is possible to take pictures at angles and situations that were not possible with conventional cameras. As shown in FIG. 2, for example, this action camera can use an optical system having an image pickup lens 21 and an image pickup element 22 for capturing an image formed by these image pickup lenses 31. Of these, the image pickup lens 21 is composed of a plurality of optical elements such as lenses, and a light flux from the subject is incident from the first lens 21a on the object point (subject) side. The luminous flux incident from the first lens 21a sequentially incidents on the second and subsequent lenses, and is imaged as an image of the subject on the image pickup surface of the image pickup element 22.

In particular, when the optical system shown in FIG. 2 is used for an action camera, a cushioning member made of an elastic material such as rubber is provided between the image pickup lens 21 and a lens barrel (not shown) from the viewpoint of alleviating the impact applied to the optical system. It may be provided.

However, such an action camera is often used outdoors, and unless a cover or the like is provided on the surface of the image pickup lens 21 of the action camera, the optical glass is damaged by a strong wind or a flying object generated by the strong wind. Often. Further, in particular, the first lens 21a is liable to be damaged by a strong wind or a flying object.

Therefore, by using the optical glass of the present invention for the image pickup lens 21 used in the action camera, more preferably the first lens 21a on the subject (object point) side, the image pickup lens 21 is damaged by strong wind or flying objects. Can be made less likely to occur.

[Use of in-vehicle camera]
Further, the in-vehicle camera is a camera mounted on the outer side of the vehicle body of the automobile, and as shown in FIG. 2, the image pickup lens 21 and an image pickup element (CCD) that captures an image formed by the image pickup lens 21. ) 22, and an optical system having the above can be used. Of these, the image pickup lens 21 is composed of a plurality of optical elements such as lenses, and a light flux from the subject is incident from the first lens 21a on the object point (subject) side. The luminous flux incident from the first lens 21a sequentially incidents on the second and subsequent lenses, and is imaged as an image of the subject on the image pickup surface of the image pickup element 22.

As in-vehicle cameras, those mounted on the rear part of the vehicle body and used for checking the rear, those mounted on the front part of the vehicle body and used for checking the front and sides, and those used for checking the distance to the vehicle in front. And so on.

However, the optical glass of the image pickup lens 21 in such an in-vehicle camera is often damaged by strong winds and flying objects generated by the strong wind unless a cover or the like is provided on the surface thereof. In particular, the first lens 21a was liable to be damaged by strong winds and flying objects.

Therefore, by using the optical glass of the present invention for the image pickup lens 21 used in the in-vehicle camera, more preferably the first lens 21a on the subject (object point) side, the image pickup lens 21 is damaged by strong wind or flying objects. Can be made less likely to occur.

As the lens for an in-vehicle camera, at least one surface of the plurality of lenses may be an aspherical surface. As a result, it is possible to improve the optical characteristics by reducing the aberration caused by the lens and improving the resolution.

[Use of headlights for transport aircraft]
Further, as the headlight 3 for a transport machine, for example, as shown in FIG. 3, a light source 32 for emitting laser light, a wavelength conversion element 33 arranged on the optical axis of the light source 32, and a wavelength conversion element 33 arranged so as to cover them are provided. A cover member 38 is provided, and light having a desired color temperature such as white light (including one obtained by superimposing a plurality of monochromatic lights) is emitted from a wavelength conversion element 33 to which a laser beam from a light source 32 is incident. Can be done.

As the light source 32, for example, a laser diode that emits a laser beam in the wavelength range of blue or ultraviolet light, that is, about 500 nm or less is used, but the light source 32 is not limited thereto. Then, the emitted light from the light source 32 is collected in the direction of the wavelength conversion element 33 by using, for example, a condenser lens 37, and is irradiated to the wavelength conversion element 33 as laser light.

Then, the emission light from the wavelength conversion element 33 uses the reflector 34 to change the radiation direction D2 of the emission light to the main radiation direction D1 of the headlight 3 for the transport machine, and also to change the direction of the optical path. After generating a desired light image of the headlight 3 for a transport machine, light can be taken out from an arbitrarily provided transparent cover member 38. Here, the light guide element 39 may be provided immediately before the wavelength conversion element 33 or so as to fix the wavelength conversion element 33, whereby the light coming from the light source 32 may be guided to the wavelength conversion element 33. Further, in order to absorb the reflected light generated when the light from the light source 32 is applied to the wavelength conversion element 33 and the light guide element 39, the shield element 35 may be provided on the optical path of the reflected light. Further, a cooling fin 36 may be provided as a carrier element for fixing the wavelength conversion element 33 in the reflector 34.

However, in such a transporter headlight 3, the strong wind and the flying objects generated by the strong wind hit the optical glass facing the outside of the transporter, more specifically, the optical glass constituting the cover member 38. The glass was broken.

Therefore, by using the optical glass of the present invention as an optical element such as a cover member 38 in the headlight 3 for a transport machine shown in FIG. 3, for example, the cover member 38 may be damaged due to a strong wind or a flying object generated by the strong wind. , It is possible to reduce the damage to the entire headlight 3 for the transport machine.

<Use of optical elements in equipment with displacement means>
Further, examples of the use of the device having the displacement means include an action camera, an in-vehicle camera, and a headlight for a transport aircraft. In these applications, the optical element is often subjected to a mechanical impact when the device is displaced by the displacement means or when the device is braked. By using the optical glass of the present invention for these purposes, it is possible to reduce damage to the optical element during displacement or braking of the device.

[Use of action camera]
Of these, in the application of action cameras, when the action camera is attached to a device having a displacement means, the impact due to the displacement means or the device falling, or the shaking when the device is displaced (moved) by the displacement means. , The optical element is liable to be damaged due to the reaction when the displacement of the device is stopped by the displacement means.

Therefore, by using the optical glass of the present invention for each optical element constituting the image pickup lens 21, for example, in the optical system of the action camera shown in FIG. 2, shaking when the action camera is displaced and displacement of the action camera It is possible to prevent damage to the optical element due to the reaction when the camera is stopped.

[Use of in-vehicle camera]
Further, in the use of optical devices fixed to the transport aircraft, such as in-vehicle cameras and headlights for transport aircraft, as in the case of action cameras, shaking when driving the transport aircraft and stopping the transport aircraft are required. The reaction tends to damage the optical element.

Among these, regarding the use of the in-vehicle camera, for example, in the optical system of the in-vehicle camera shown in FIG. 2, by using it for each optical element constituting the image pickup lens 21, shaking when driving the transport aircraft and the transport aircraft can be used. It is possible to prevent damage to the optical element due to the reaction when the optical element is stopped.

[Use of headlights for transport aircraft]
Further, regarding the use of the headlight for a transport aircraft, for example, in the headlight 3 for a transport aircraft shown in FIG. 3, when the transport aircraft is driven by using it for an optical element such as a condenser lens 37 and a cover member 38. It is possible to prevent damage to the optical element due to shaking or reaction when the transport aircraft is stopped.

The compositions of Examples (No. 1 to No. 13) and Comparative Examples (No. A) of the present invention, and the refractive index ( _{nd), Abbe number (ν d )} , and spectral transmittance of these glasses are 5. Tables 1 and 2 show the wavelengths (λ ₅ and λ ₈₀ ) showing% and 80%, specific gravity, glass transition point, bending point, and falling ball test results. The following examples are for illustrative purposes only, and are not limited to these examples.

The glasses of the examples and comparative examples of the present invention are ordinary optical glasses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphoric acid compounds, which correspond to each other as raw materials for each component. The high-purity raw materials used in the above are selected, weighed so as to have the composition ratio of each example shown in the table, mixed uniformly, and then put into a platinum pit, depending on the difficulty of melting the glass composition. After melting in an electric furnace in a temperature range of 1200 to 1500 ° C. for 2 to 4 hours, the glass was homogenized by stirring, cast into a mold or the like, and slowly cooled to prepare glass.

The refractive index (nd) and Abbe number (ν _d ) of the glass of Examples and Comparative Examples are shown by the measured values with respect to the _d line (587.56 nm) of the helium lamp. The Abbe number (ν _d ) is the refractive index of the d line, the refractive index of the hydrogen lamp with respect to the F line (486.13 nm) (n _F ), and the refractive index with respect to the C line (656.27 nm) (n _C ). It was calculated from the formula of Abbe number (ν _d ) = [(n _d -1) / (n _F − n _C )] using the value of.

The transmittance of the glass of Examples and Comparative Examples was measured according to the Japan Optical Glass Industry Association standard JOBIS02. In the present invention, the presence or absence and degree of coloring of the glass were determined by measuring the transmittance of the glass. Specifically, a face-to-face parallel polished product having a thickness of 10 ± 0.1 mm was measured for a spectral transmittance of 200 to 800 nm according to JIS Z8722, and λ ₅ (wavelength at a transmittance of 5%) and λ ₇₀ (transmittance). Wavelength at 70%) was determined.

The specific gravity of the glass of Examples and Comparative Examples was measured based on the Japan Optical Glass Industry Association standard JOBIS05-1975 “Method for measuring the specific gravity of optical glass”.

Further, the glass transition point (Tg) and the yield point (At) of the glass of Examples and Comparative Examples are the temperature and the elongation of the sample according to the Japan Optical Glass Industry Association standard JOBIS08-2003 “Measurement method of thermal expansion of optical glass”. It was obtained from the thermal expansion curve obtained by measuring the relationship with.

In addition, as a result of the falling ball test of the glass of the examples and the comparative examples, a steel ball of 23.8 g (diameter of about 1.8 cm) made of SUJ-2 has a width of 50 mm × 50 mm or more and a thickness of 5 mm. When freely dropped onto the center of the main surface of an optical two-sided polished optical glass with a diameter of 30 mm and a thickness of 2 mm, which is placed on the main surface of a rubber sheet made of natural rubber, at least a part of the optical glass is formed. The minimum height [cm] that is damaged by cracks, chips, cracks, etc. was determined.

As shown in the table, the optical glass of the embodiment of the present invention had a ball drop test result of 100 cm or more, more specifically 110 cm or more. On the other hand, in the glass of Comparative Example (No. A), the result of the falling ball test was less than 100 cm.

Further, all of the optical glasses of the examples of the present invention have a refractive index ( _{nd) in the range of 1.47 to 1.54 and an Abbe number (ν d )} in the range of 60 to 68, which are within the desired range. there were.

Further, the optical glass of the embodiment of the present invention had a λ ₈₀ (wavelength at a transmittance of 80%) of 400 nm or less, and more specifically, 350 nm or less. Further, the optical glass of the embodiment of the present invention had λ ₅ (wavelength at a transmittance of 5%) of 360 nm or less, and more specifically, 320 nm or less.

Further, all of the optical glasses of the examples of the present invention had a glass transition point of 600 ° C. or lower, more specifically 560 ° C. or lower, which was within a desired range.

Further, all of the optical glasses of the examples of the present invention had a yield point of 700 ° C. or lower, more specifically 630 ° C. or lower, which was within a desired range.

Further, all of the optical glasses of the examples of the present invention had a specific gravity of 4.50 or less, more specifically 3.70 or less, which were within a desired range.

Moreover, none of the optical glasses of the examples of the present invention was devitrified and was stable glass.

Therefore, the optical glass of the embodiment of the present invention has excellent falling ball test results while having a refractive index ( _{nd) and an Abbe number (ν d )} within desired ranges, and the glass is not easily broken even by the falling ball test. It became clear. Therefore, it is presumed that the optical glass of the embodiment of the present invention has high impact resistance.

It was also clarified that the optical glass of the embodiment of the present invention has less coloring, is easy to press-mold, and has a small specific gravity.

Although the present invention has been described in detail above for the purpose of illustration, the present embodiment is merely for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the idea and scope of the present invention. Will be understood.

11 Camera device body 12 Photograph lens barrel 12a Male screw part 13 Mounting part 131 Base part 132 Holder part 132a Female thread part 133 Washer 134 Stopper part 14 Housing 14a Incident window 15 Image sensor 16 Substrate

21 Image sensor 21a First lens 32 Image sensor

3 Headlight for transport machine 32 Light source 33 Wavelength conversion element 34 Reflector 35 Shield element 36 Cooling fin 37 Condensing lens 38 Cover member 39 Light guide element D1 Main radiation direction D2 Radiation direction

Claims (2)

By mass% based on oxides,
SiO ₂ component 50.0-74.0%,
The total amount of the B ₂ O ₃ component 1.0 to 25.0% and the Rn ₂ O component (in the formula, Rn is at least one of Li, Na, and K) is 5.0 to 30.0%. ,
Al ₂ O ₃ component exceeds 0%,
It has an optical constant with a refractive index (nd) in the range of 1.47 to 1.54 and an Abbe number (νd) in the range of 60 to 68.
The minimum height at which the optical glass breaks when it is freely dropped onto an optical glass having a diameter of 30 mm and a thickness of 2 mm, in which a 23.8 g steel ball is placed on the main surface of a rubber sheet made of natural rubber having a thickness of 5 mm. Optical glass used for outdoor optical equipment having a size of 100 cm or more or optical equipment having a displacement means. The optical glass according to claim 1, which is used for a surveillance camera, an action camera, an in-vehicle camera, or a headlight.

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