Glass

Abstract

Provided is a glass having a high refractive index and high transmittance. The glass (10), expressed in mol% on an oxide basis, is Bi2O3 > 11.2%; contains at least one type selected from the group consisting of TeO2, TiO2, WO3, Nb2O5, and Bi2O3; fulfills 3.78 ≤ Nb2O5 / (TeO2+ TiO2+ WO3 + Nb2O5+ Bi2O3) × 100 ≤ 19.2; and has a total Fe, Cr, and Ni content of less than 4 ppm in mass terms.

Description

[Technical Field]

[0001] The present invention relates to glass. [Background technology]

[0002] In recent years, there has been a demand for glass with a high refractive index and high transmittance. In particular, in wearable devices such as head-mounted displays that realize AR (Augumented Reality), VR (Virtual Reality), MR (Mixed Reality), etc., a light guide plate with a high refractive index and high transmittance for visible light is required. For example, Patent Document 1 describes an optical glass with a high refractive index and high transmittance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5682171 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is room for improvement in the transmittance of the optical glass of Patent Document 1. Therefore, there is a demand for glass with a high refractive index and high transmittance.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a glass having a high refractive index and high transmittance. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objects, the glass according to the present disclosure contains, in mole % on an oxide basis, Bi2O3 > 11.2%, one or more elements selected from the group consisting of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, 3.78 ≦ Nb2O5 / (TeO2 + TiO2 + WO3 + Nb2O5 + Bi2O3) × 100 ≦ 19.2, and the total content of Fe, Cr, and Ni, expressed by mass, is less than 4 ppm. [Effects of the Invention]

[0007] According to the present invention, a glass having a high refractive index and high transmittance can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of the glass according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the glass according to this embodiment when it is used as a glass plate. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments, and when there are multiple embodiments, the present invention also includes configurations that are made by combining the respective embodiments. Furthermore, numerical values ​​include the range of rounding.

[0010] (glass) FIG. 1 is a schematic diagram of glass according to this embodiment. As shown in FIG. 1, glass 10 according to this embodiment is a plate-shaped glass plate, but the shape of glass 10 is not limited to a plate shape and may be any shape. In this embodiment, glass 10 is used as a light guide plate. More specifically, glass 10 is used as a light guide plate for a head-mounted display. A head-mounted display is a display device (wearable device) that is worn on a person's head. However, the use of glass 10 is arbitrary and is not limited to being used as a light guide plate, nor is it limited to being used in a head-mounted display.

[0011] (Glass composition) The composition of the glass 10 will be described below.

[0012] (Bi2O3) In glass 10, the Bi2O3 content, expressed in mole percent on an oxide basis, is greater than 11.2%, preferably greater than 15.0%, more preferably greater than 20.0%, and even more preferably greater than 25.0%. A Bi2O3 lower limit greater than 11.2% is preferable because it results in a high refractive index. Furthermore, in glass 10, the Bi2O3 content, expressed in mole percent on an oxide basis, is preferably less than 45.0%, more preferably less than 40.0%, even more preferably less than 35.0%, and even more preferably less than 32.0%. A Bi2O3 upper limit less than 45.0% is preferable because it results in high transmittance. Thus, by having the Bi2O3 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light. Note that the "content" here refers to the mole percent of the oxide content, expressed in mole percent on an oxide basis, when the total mole percent of glass 10 is taken as 100%. For example, "a Bi2O3 content of greater than 11.2%" means that, in mole percent on an oxide basis, when the mole percent of the total amount of glass 10 is 100%, the Bi2O3 content is greater than 11.2%.

[0013] (Nb2O5) In glass 10, the Nb2O5 content, expressed in mole percent on an oxide basis, is preferably greater than 2.0%, more preferably greater than 3.0%, even more preferably greater than 4.0%, and even more preferably greater than 5.0%. A lower limit of Nb2O5 greater than 2.0% is preferable because it results in a high refractive index. Furthermore, the Nb2O5 content, expressed in mole percent on an oxide basis, is preferably less than 15.0%, more preferably less than 10.0%, even more preferably less than 9.0%, and even more preferably less than 8.0%. An upper limit of Nb2O5 less than 15.0% is preferable because it maintains the stability of the glass. Thus, by having the Nb2O5 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0014] (TeO2) The TeO2 content of glass 10, expressed in mole percent on an oxide basis, is preferably greater than 10.1%, more preferably greater than 20.3%, even more preferably greater than 23.0%, and even more preferably greater than 25.0%. A TeO2 lower limit of greater than 10.1% is preferred because it results in a high refractive index. Furthermore, the TeO2 content of glass 10, expressed in mole percent on an oxide basis, is preferably less than 33.1%, more preferably less than 30.0%, even more preferably less than 29.0%, and even more preferably less than 28.0%. A TeO2 upper limit of less than 33.1% is preferred because it results in high transmittance. Thus, by having the TeO2 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0015] (P2O5) Glass 10 preferably contains P2O5 as an essential component. While glass can be obtained without P2O5, the glass becomes unstable and manufacturability deteriorates. Therefore, the P2O5 content of glass 10, expressed as mole percent on an oxide basis, is preferably greater than 2.0%, more preferably greater than 4.0%, even more preferably greater than 6.0%, and even more preferably greater than 8.0%. A P2O5 lower limit of greater than 2.0% is preferred because it maintains glass stability. Furthermore, the P2O5 content of glass 10, expressed as mole percent on an oxide basis, is preferably less than 18.0%, more preferably less than 16.0%, even more preferably less than 14.0%, and even more preferably less than 12.0%. A P2O5 upper limit of less than 18.0% is preferred because it results in a high refractive index. Thus, by having the P2O5 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0016] (B2O3) In glass 10, the B2O3 content, expressed in mole percent on an oxide basis, is preferably greater than 12.0%, more preferably greater than 14.0%, and even more preferably greater than 16.0%. Having a lower limit for B2O3 greater than 12.0% is preferable because it allows the stability of the glass to be maintained. Furthermore, in glass 10, the B2O3 content, expressed in mole percent on an oxide basis, is preferably less than 40.0%, more preferably less than 35.0%, and even more preferably less than 30.0%. Having an upper limit for B2O3 less than 40.0% is preferable because it allows a high refractive index to be achieved. Having a B2O3 content within this range allows glass 10 to maintain glass stability while maintaining high transmittance for visible light.

[0017] (TiO2) Glass 10 is an optional component, and the TiO2 content, expressed in mole percent on an oxide basis, is preferably less than 1.0%, more preferably less than 0.5%, and even more preferably less than 0.1%. A TiO2 upper limit of less than 1.0% is preferred because it results in high transmittance. More specifically, the inclusion of TiO2 results in a high refractive index, but at the expense of reduced transmittance. Therefore, by keeping the TiO2 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0018] (Ta2O5) The Ta2O5 content of glass 10, expressed in mole percent on an oxide basis, is preferably less than 1.0%, more preferably less than 0.5%, and even more preferably less than 0.1%. Having the upper limit of Ta2O5 less than 1.0% is preferable because it allows for cost reduction while maintaining glass stability. More specifically, the inclusion of Ta2O5 results in a high refractive index, but the glass becomes unstable and devitrification becomes more likely. Furthermore, it is expensive, leading to increased costs. By keeping the Ta2O5 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0019] (WO3) In glass 10, the WO3 content, expressed in mole percent on an oxide basis, is preferably less than 1.0%, more preferably less than 0.5%, and even more preferably less than 0.1%. Having the upper limit of WO3 less than 1.0% is preferable because it results in high transmittance. Furthermore, although the inclusion of WO3 results in a high refractive index, it is an optional component because it reduces transmittance. By keeping the WO3 content within this range, glass 10 can be made to have a high refractive index while maintaining high transmittance for visible light.

[0020] (ZnO) In glass 10, the ZnO content, expressed in mole percent on an oxide basis, is preferably greater than 1.0%, more preferably greater than 2.0%, and even more preferably greater than 3.0%. A lower limit of ZnO greater than 1.0% is preferable because it maintains the stability of the glass. Furthermore, in glass 10, the ZnO content, expressed in mole percent on an oxide basis, is preferably less than 15.0%, more preferably less than 12.0%, and even more preferably less than 10.0%. A higher ZnO content of less than 15.0% is preferable because it results in a high refractive index. Thus, by having the ZnO content within this range, glass 10 can maintain its stability while maintaining a high refractive index for visible light.

[0021] (TeO2+TiO2+WO3+Nb2O5+Bi2O3) In glass 10, the total content of (TeO2 + TiO2 + WO3 + Nb2O5 + Bi2O3), i.e., the total content of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, expressed in mole percent on an oxide basis, is preferably greater than 50.0%, more preferably greater than 55.0%, and even more preferably greater than 60.0%. A lower limit of these total contents greater than 50.0% is preferred because a high refractive index is achieved. Furthermore, in glass 10, the total content of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, expressed in mole percent on an oxide basis, is preferably less than 75.0%, more preferably less than 70.0%, and even more preferably less than 65.0%. A higher transmittance is preferred because an upper limit of these total contents less than 75.0% is preferred. In this way, by ensuring that the total content of TeO2, TiO2, WO3, Nb2O5, and Bi2O3 falls within this range, it is possible to achieve a high refractive index while maintaining high transmittance for visible light in glass 10. However, TiO2 and WO3 may not be contained.

[0022] (Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100) Glass 10 contains one or more elements selected from the group consisting of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, and preferably contains Nb2O5 in addition to one or more elements selected from the group consisting of TeO2, TiO2, WO3, and Bi2O3. Glass 10 preferably has a Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 ratio greater than 3.78, more preferably greater than 5.0, even more preferably greater than 7.0, and even more preferably greater than 10.0. Having a lower limit of Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 greater than 3.78 is preferred because it results in a high refractive index. Furthermore, for glass 10, Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 is preferably less than 19.2, more preferably less than 15.0, even more preferably less than 14.0, and even more preferably less than 12.0. Having Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 less than 19.2 is preferable because it results in high transmittance. Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 refers to the ratio of the content of Nb2O5, expressed as mole percent on an oxide basis, to the total content of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, expressed as mole percent on an oxide basis, multiplied by 100. In this way, when Nb2O5 / (TeO2+TiO2+WO3+Nb2O5+Bi2O3)×100 is in this range, it is possible to achieve a high refractive index while maintaining high transmittance for visible light in glass 10. However, TiO2 and WO3 do not necessarily need to be contained.

[0023] (Bi2O3+Nb2O5+TeO2+P2O5+B2O3+TiO2+Ta2O5+WO3+ZnO) Glass 10 preferably has a total content of (Bi2O3 + Nb2O5 + TeO2 + P2O5 + B2O3 + TiO2 + Ta2O5 + WO3 + ZnO), i.e., the total content of the oxides mentioned above, Bi2O3, Nb2O5, TeO2, P2O5, B2O3, TiO2, Ta2O5, WO3, and ZnO, of 100%. However, it is permissible for glass 10 to contain SiO2 and Al2O3 eluted from a melting vessel such as a quartz crucible or an alumina crucible. It is also permissible for glass 10 to contain impurities unavoidable during manufacturing, i.e., unavoidable impurities. In this case, the total content of SiO2 and Al2O3 in glass 10, expressed in mole percent on an oxide basis, is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less. In other words, it is preferable that glass 10 contains no elements other than Bi2O3, Nb2O5, TeO2, P2O5, B2O3, TiO2, Ta2O5, WO3, and ZnO, excluding unavoidable impurities. Glass 10 with this composition can have a high refractive index and high transmittance for visible light. However, TiO2 and WO3 may not be included.

[0024] (Fe, Cr, Ni content) The total content of Fe, Cr, and Ni in glass 10 is less than 4 ppm by mass, preferably 3 ppm or less, more preferably 2 ppm or less, and even more preferably 1 ppm or less, relative to the total mass of glass 10. Here, Fe, Cr, and Ni do not refer only to the elemental metals Fe, Cr, and Ni contained in glass 10, but may also include the elemental metals and compounds of Fe, Cr, and Ni. In other words, the total content of Fe, Cr, and Ni can be said to include the content of the elemental metals Fe, Cr, and Ni and the content of Fe, Cr, and Ni ions in the compounds. By keeping the total content of the coloring transition metals Fe, Cr, and Ni within this range, the visible light transmittance of glass 10 can be prevented from decreasing, thereby achieving high visible light transmittance. The total content of Fe, Cr, and Ni can be measured by ICP mass spectrometry. An Agilent 8800 manufactured by Agilent Technologies, for example, can be used as a measuring instrument.

[0025] The total content of Fe, Cr, Ni, Cu, Mn, Co, and V in glass 10 is preferably less than 4 ppm, more preferably 3 ppm or less, even more preferably 2 ppm or less, and even more preferably 1 ppm or less, by mass, relative to the total content of glass 10. Here, Fe, Cr, Ni, Cu, Mn, Co, and V, like the Fe, Cr, and Ni mentioned above, do not refer only to the individual metals Fe, Cr, Ni, Cu, Mn, Co, and V contained in glass 10, but may also include the individual metals and compounds of Fe, Cr, Ni, Cu, Mn, Co, and V. In other words, the total content of Fe, Cr, Ni, Cu, Mn, Co, and V can be said to include the content of the individual metals Fe, Cr, Ni, Cu, Mn, Co, and V and the content of Fe, Cr, Ni, Cu, Mn, Co, and V ions in the compounds. When the total content of the above coloring transition metal components falls within this range, a decrease in the visible light transmittance of glass 10 can be prevented, thereby achieving high visible light transmittance for glass 10. The total content of the above components can be measured by ICP mass spectrometry.

[0026] (Pb content) The total Pb content of glass 10, by mass, is preferably less than 1000 ppm, more preferably 100 ppm or less, and even more preferably 10 ppm or less, relative to the entire glass 10. In other words, glass 10 preferably contains substantially no Pb. Here, Pb, like Fe, Cr, and Ni, does not refer only to the Pb element contained in glass 10, but may also include the Pb element and compounds. In other words, the Pb content can be said to include the Pb element content and the Pb ion content in the compounds. The Pb content can be measured by ICP mass spectrometry.

[0027] (Refractive index n d ) The glass 10 having the above composition has a refractive index n d is preferably 2.00 or more, more preferably 2.05 or more, and even more preferably 2.10 or more. d When the refractive index n is in this range, a high refractive index for visible light can be achieved. d indicates the refractive index at the d line of helium (wavelength 587.6 nm). d can be measured using the V-block method.

[0028] (wavelength λ 70 ) Here, the wavelength at which the external transmittance is 70% for a plate thickness of 10 mm is defined as wavelength λ 70 That is, the wavelength λ 70 This refers to the wavelength of light at which the external transmittance is 70% for a sample with a thickness of 10 mm. 70 The wavelength λ is preferably less than 450 nm, more preferably 445 nm or less, even more preferably 440 nm, and even more preferably 435 nm or less. 70 When the wavelength λ is in this range, high transmittance for visible light can be achieved. 70The external transmittance for calculating the transmittance can be measured using a spectrophotometer (Hitachi High-Technologies Corporation: U-4100) on a sample that is 10 mm thick and mirror-polished on both sides.

[0029] (Light transmittance) Furthermore, the glass 10 preferably has an internal transmittance of 91.5% or more, preferably 93.0% or more, and more preferably 95.0% or more for light with a wavelength of 450 nm at a plate thickness (thickness) of 10 mm. By having the internal transmittance of light with a wavelength of 450 nm fall within this range, high transmittance for visible light can be achieved. The internal transmittance of a 10 mm thick glass can be calculated from the measured values ​​of the external transmittance of two types of glass with different plate thicknesses and the following formula (1). Note that the external transmittance means the transmittance including surface reflection loss. In formula (1), X is the internal transmittance of the 10 mm thick glass, T1 and T2 are the external transmittances, and Δd is the difference in thickness between the samples.

[0030]

number

[0031] (Glass form) The glass 10 according to this embodiment is preferably optical glass, and is preferably a glass plate having a thickness of 0.01 mm or more and 2.0 mm or less. A thickness of 0.01 mm or more can prevent breakage of the glass 10 during handling or processing. It can also prevent deflection of the glass 10 due to its own weight. This thickness is more preferably 0.1 mm or more, even more preferably 0.2 mm or more, and even more preferably 0.3 mm or more. On the other hand, a thickness of 2.0 mm or less can reduce the weight of optical elements using the glass 10. This thickness is more preferably 1.5 mm or less, even more preferably 1.0 mm or less, and even more preferably 0.8 mm or less.

[0032] When the glass 10 according to this embodiment is a glass plate, the area of ​​the main surface is 8 cm 2 This area is preferably 8cm or more. 2If the area is more than 30 cm, a large number of optical elements can be arranged, improving productivity. 2 More preferably, 170 cm 2 More preferably, it is 300 cm or more. 2 More preferably, it is 1000 cm 2 On the other hand, if the area is 6500 cm 2 If the area is less than 4500 cm, the glass plate can be easily handled and breakage during handling or processing can be suppressed. 2 More preferably, it is 4000 cm or less. 2 and even more preferably 3000 cm 2 It is particularly preferably 2000 cm 2 The following is the result.

[0033] When the glass 10 according to this embodiment is a glass plate, 25 cm 2 The LTV (Local Thickness Variation) in the above range is preferably 2 μm or less. By having a flatness in this range, it is possible to form a nanostructure of the desired shape on the main surface using imprinting technology or the like, and to obtain the desired light-guiding characteristics. In particular, in the case of a light guide, ghosting and distortion due to differences in optical path length can be prevented. This LTV is more preferably 1.5 μm or less, even more preferably 1.0 μm or less, and particularly preferably 0.5 μm or less.

[0034] When the glass 10 according to this embodiment is formed into a circular glass plate having a diameter of 8 inches, the warpage is preferably 50 μm or less. If the warpage of this glass 10 is 50 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light-guiding characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage of this glass 10 is more preferably 40 μm or less, even more preferably 30 μm or less, and particularly preferably 20 μm or less.

[0035] Furthermore, when the glass 10 according to this embodiment is formed into a circular glass plate with a diameter of 6 inches, the warpage is preferably 30 μm or less. If the warpage of this glass 10 is 30 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light-guiding characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage of this glass 10 is more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 10 μm or less.

[0036] Furthermore, when the glass 10 according to this embodiment is a square glass plate with sides of 6 inches, the warpage is preferably 100 μm or less. If the warpage of this glass 10 is 100 μm or less, it is possible to form a nanostructure of a desired shape on the main surface using imprinting technology or the like, and the desired light-guiding characteristics can be obtained. When multiple light guides are to be obtained, they can be obtained with stable quality. The warpage of this glass 10 is more preferably 70 μm or less, even more preferably 50 μm or less, even more preferably 35 μm or less, and particularly preferably 20 μm or less.

[0037] 2 is a cross-sectional view of a glass plate made from the glass according to this embodiment. When the glass 10 according to this embodiment is used as the glass plate G1, the "warpage" is a difference C between the maximum value B and the minimum value A of the perpendicular distance between a reference line G1D of the glass plate G1 and a center line G1C of the glass plate G1 in any cross section that passes through the center of a main surface G1F of the glass plate G1 and is perpendicular to the main surface G1F of the glass plate G1.

[0038] The intersection line between the arbitrary orthogonal cross section and the main surface G1F of the glass sheet G1 is defined as the base line G1A. The intersection line between the arbitrary orthogonal cross section and the other main surface G1G of the glass sheet G1 is defined as the top line G1B. Here, the center line G1C is a line connecting the centers of the glass sheet G1 in the thickness direction. The center line G1C is calculated by finding the midpoint between the base line G1A and the top line G1B with respect to the laser irradiation direction, which will be described later.

[0039] The reference line G1D is determined as follows. First, a base line G1A is calculated based on a measurement method that cancels the influence of the weight. A straight line is determined from the base line G1A using the least squares method. The determined straight line is the reference line G1D. A known method is used as the measurement method that cancels the influence of the weight.

[0040] For example, the main surface G1F of the glass plate G1 is supported at three points, and a laser displacement meter is used to irradiate the glass plate G1 with a laser, thereby measuring the height of the main surface G1F and the other main surface G1G of the glass plate G1 from an arbitrary reference plane.

[0041] Next, the glass plate G1 is inverted, and three points on the other main surface G1G opposite to the three points on which one main surface G1F is supported are supported, and the heights of the main surface G1F and the other main surface G1G of the glass substrate G1 from an arbitrary reference plane are measured. The influence of gravity is cancelled out by averaging the heights of each measurement point before and after inversion. For example, before inversion, the height of the main surface G1F is measured as described above. After inverting the glass plate G1, the height of the other main surface G1G is measured at a position corresponding to the measurement point on the main surface G1F. Similarly, before inversion, the height of the other main surface G1G is measured. After inverting the glass plate G1, the height of the other main surface G1F is measured at a position corresponding to the measurement point on the other main surface G1G. The warpage is measured, for example, by a laser displacement meter.

[0042] Furthermore, in the glass 10 according to this embodiment, the surface roughness Ra of the main surface is preferably 2 nm or less. Having an Ra in this range allows for the formation of nanostructures of desired shapes on the main surface using imprinting techniques or the like, and also allows for the attainment of desired light-guiding characteristics. In particular, in light guides, diffuse reflection at interfaces can be suppressed, preventing ghosting and distortion. This Ra is more preferably 1.7 nm or less, even more preferably 1.4 nm or less, even more preferably 1.2 nm or less, and particularly preferably 1 nm or less. Here, the surface roughness Ra is the arithmetic mean roughness defined in JIS B0601 (2001). In this specification, the value is measured over an area of ​​10 μm × 10 μm using an atomic force microscope (AFM).

[0043] (Glass manufacturing method) The method for manufacturing glass 10 according to this embodiment is not particularly limited, and existing methods for manufacturing sheet glass can be used. For example, known methods such as the float method, fusion method, and roll-out method can be used. However, in order to prevent deterioration of transmittance due to the inclusion of impurities, it is preferable that the material of the container (crucible) for containing raw materials when melting the raw materials in glass 10 is Au or an Au alloy.

[0044] Furthermore, in the glass 10 of this embodiment, it is preferable to carry out an operation to increase the water content in the molten glass during the melting process in which glass raw materials are heated and melted in a melting vessel to obtain molten glass. The operation to increase the water content in the glass is not limited, but possible examples include adding water vapor to the melting atmosphere and bubbling a gas containing water vapor into the melt. The operation to increase the water content is not essential, but can be carried out for purposes such as improving transmittance and clarity. Furthermore, glass 10 of the present embodiment containing alkali metal oxides such as LiO and NaO can be chemically strengthened by substituting Li ions with Na ions or K ions, or Na ions with K ions. In other words, chemical strengthening can improve the strength of optical glass.

[0045] (effect) As described above, glass 10 according to this embodiment has a Bi2O3 > 11.2% molar percentage (based on oxides), i.e., a Bi2O3 content greater than 11.2%. Glass 10 also contains one or more elements selected from the group consisting of TeO2, TiO2, WO3, Nb2O5, and Bi2O3, and satisfies 3.78 ≤ Nb2O5 / (TeO2 + TiO2 + WO3 + Nb2O5 + Bi2O3) × 100 ≤ 19.2, i.e., Nb2O5 / (TeO2 + TiO2 + WO3 + Nb2O5 + Bi2O3) × 100 is 3.78 or greater and 19.2 or less. Glass 10 also has a total content of Fe, Cr, and Ni, expressed by mass, of less than 4 ppm. This composition allows glass 10 to have a high refractive index while maintaining high transmittance for visible light.

[0046] The glass 10 has an external transmittance of 70% at a wavelength λ 70 The glass 10 preferably has a wavelength λ of less than 450 nm. 70 When the value of the transmittance falls within this range, high transmittance for visible light is achieved.

[0047] Furthermore, glass 10 preferably contains P2O5 as an essential component. By including P2O5, glass 10 can have a high refractive index while maintaining high transmittance for visible light, and can also stabilize the glass.

[0048] Furthermore, it is preferable that the glass 10 has a TeO2 content of greater than 10.1%, expressed in mole percent on an oxide basis, of TeO2 > 10.1%. When the TeO2 content of glass 10 is in this range, it is possible to achieve a high refractive index while maintaining high transmittance for visible light.

[0049] Furthermore, it is preferable that glass 10 has Bi2O3 > 15.0% in mole percent on an oxide basis, i.e., the Bi2O3 content is greater than 15.0%. When the Bi2O3 content falls within this range, glass 10 can have a high refractive index while maintaining high transmittance for visible light.

[0050] Furthermore, it is preferable that glass 10 has Nb2O5>15.0%, that is, an Nb2O5 content of greater than 15.0%, expressed in mole percent on an oxide basis. When the Nb2O5 content of glass 10 is in this range, it is possible to achieve a high refractive index while maintaining high transmittance for visible light.

[0051] The glass 10 has a refractive index n d The glass 10 preferably has a refractive index n d When the refractive index is in this range, the refractive index becomes high for visible light.

[0052] Furthermore, the glass 10 is preferably used as a light guide plate. The glass 10 having such a composition has a high refractive index and high transmittance, and is therefore suitable for use as a light guide plate.

[0053] The glass 10 produced in this manner is useful for a variety of optical elements, among which (1) it is particularly suitable for use in light guides, filters, lenses, etc. used in wearable devices, such as projector-equipped glasses, eyeglass-type and goggle-type displays, virtual reality and augmented reality display devices, and virtual image display devices, and (2) lenses and cover glass, etc. used in vehicle-mounted cameras and robot visual sensors. It is also suitable for use in applications exposed to harsh environments, such as vehicle-mounted cameras. It is also suitable for use in applications such as glass substrates for organic electroluminescence (EL) devices, substrates for wafer-level lens arrays, substrates for lens units, substrates for lens formation by etching, and optical waveguides. The glass 10 of the present embodiment described above has a high refractive index and high transmittance, and has good manufacturing properties, making it suitable as an optical glass for wearable devices, vehicles, and robots. Furthermore, optical components having an antireflection coating formed on a major surface of the glass 10, the antireflection coating being a dielectric multilayer film of 4 to 10 layers, in which low-refractive-index films such as SiO2 and high-refractive-index films such as TiO2 are alternately stacked, are also suitable for wearable devices, vehicles, and robots.

[0054] (Example) Next, examples will be described. Note that the embodiment may be modified as long as the effects of the invention are achieved. In the examples, glasses with different compositions were prepared. The refractive index and transmittance of each glass were evaluated. This will be explained in more detail below.

[0055] Tables 1 and 2 show the materials used in the glasses of the examples. Tables 1 and 2 show the contents, expressed in mole percent on an oxide basis, of the materials used to prepare the glasses for Examples 1 to 47. The amount of impurities in the raw materials in Tables 1 and 2 refers to the amount of components other than those listed in Tables 1 and 2 that were contained in the raw materials, with "low" indicating less than 3 ppm of the total raw materials and "high" indicating 3 ppm or more of the total raw materials. In Tables 1 and 2, "Te+Ti+W+Nb+Bi" refers to the total content, expressed in mole percent on an oxide basis, of TeO2, TiO2, WO3, Nb2O5, and Bi2O3 in the respective glasses. In addition, "Nb / (Te+Ti+W+Nb+Bi)×100" in Tables 1 and 2 refers to the ratio of the content of Nb2O5 expressed in mole percent on an oxide basis to the total content of TeO2, TiO2, WO3, Nb2O5, and Bi2O3 expressed in mole percent on an oxide basis, multiplied by 100. In addition, "Fe, Cr, Ni content" in Tables 1 and 2 refers to the total content of Fe, Cr, and Ni in each glass. The total content of Fe, Cr, and Ni was measured by ICP mass spectrometry.

[0056] [Table 1]

[0057] [Table 2]

[0058] In the examples, glasses having thicknesses of 10 mm and 1 mm were manufactured using the compositions shown in Tables 1 and 2. Evaluations were then conducted using the glasses manufactured in this manner as samples. Specifically, raw materials having the compositions shown in Tables 1 and 2 were uniformly mixed and melted in a metal crucible at 950°C for 2 hours to obtain uniform molten glass. The molten glass was then poured into a carbon mold measuring 60 mm in length, 50 mm in width, and 30 mm in height. The glass was then held at 430°C for 1 hour and then cooled to room temperature at a rate of approximately 1°C / min to obtain a glass block. Next, the glass block was cut into pieces measuring 30mm x 30mm using a cutting machine (a small cutting machine manufactured by Maruto Co., Ltd.), and the thickness was adjusted and the surface was polished using a grinding machine (SGM-6301 manufactured by Hidewa Kogyo Co., Ltd.) and a single-sided polishing machine (EJ-380IN manufactured by Engis Japan Co., Ltd.), producing glass plates measuring 30mm x 30mm and 10mm and 1mm thick.

[0059] (evaluation) The refractive index and transmittance of each glass example were evaluated for visible light. The refractive index n d The refractive index n d The refractive index was measured using a Kalnew KPR-2000. d A score of 2.0 or above was considered a pass, and a score of less than 2.0 was considered a fail. In the transmittance evaluation, the wavelength λ that shows an external transmittance of 70% for each glass at a plate thickness of 10 mm was 70 The wavelength λ 70 The transmittance was measured using a Hitachi High-Technologies Corporation U-4100. 70 A value of less than 450 nm was considered a pass, and a value of 450 nm or more was considered a fail.

[0060] (Evaluation results) As shown in Tables 1 and 2, in Examples 1 to 4 and Examples 11 to 47, which are examples, the refractive index n d and wavelength λ 70In the comparative examples 5 to 10, the wavelength λ 70 It is clear that the results are unsatisfactory and high transmittance cannot be achieved.

[0061] Additionally, to evaluate the transmittance options, the internal transmittance of light with a wavelength of 450 nm was also measured for a plate thickness of 10 mm. The internal transmittance was measured using a Hitachi High-Technologies Corporation U-4100. In evaluating the options, an internal transmittance of 91.5% or higher for light with a wavelength of 450 nm was considered preferable. As shown in Tables 1 and 2, Examples 1 to 4 and 11 to 47 showed favorable evaluation results, demonstrating that transmittance of visible light can be more favorably achieved.

[0062] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0063] 10. Glass

Claims

1. In mole percent based on oxides, 20.0% < Bi ２ O ３ < 45.0%, 8.9%≦TeO ２ ≦19.0%, 5.0%<Nb ２ O ５ < 15.0%, TeO ２ , TiO ２ , W.O. ３ , Nb ２ O ５ and Bi ２ O ３ Contains one or more selected from the group consisting of 12.4≦Nb ２ O ５ / (TeO ２ + TiO ２ +WO ３ +Nb ２ O ５ +Bi ２ O ３ ) × 100 < 15.0, 21.5%≦B 2 O 3 , 8.0%<P2O5<12.0%; The total content of Fe, Cr, and Ni is less than 4 ppm by mass. Glass.

2. Wavelength λ showing external transmittance of 70% at a plate thickness of 10 mm ７０ is less than 450 nm.

3. The glass according to claim 1, wherein P 2 O 5 is 9.6% or less, expressed in mole percent on an oxide basis.

4. In mole percent based on oxide, TeO ２ 4. The glass of claim 1 , wherein the SiO 2 content is >10.1%.

5. Refractive index n ｄ The glass according to claim 1 , wherein the refractive index is 2.0 or greater.

6. The glass according to any one of claims 1 to 5, which is used as a light guide plate.

Images