Glass substrate

Abstract

This glass substrate is a circular glass substrate having first and second main surfaces facing each other, and an end between the two main surfaces, and having a notch in a portion of the end, the glass substrate having a specific gravity of 3.00 or more, a radius r of 75 mm or more, a refractive index nd of 1.800 or more, and a ratio (Tf / Tg) of an imaginary temperature Tf (DEG C) to a glass transition temperature Tg (DEG C) of less than 1.00, when the thickness of the glass substrate is 10 mm and the relationship between the internal transmittance and the wavelength is [lambda] 70, the [lambda] 70 is 425 nm or less, where [lambda] 70 is the lowest wavelength when the internal transmittance is 70%, and the ratio (g / r) of the amount of deviation g (mm) of the center of gravity G of the glass substrate from the center P of the glass substrate to the radius r in plan view is in the range of 0.05-1.2%.

Description

Technical Field

[0001] The present invention relates to a glass substrate, and in particular to a glass substrate with high refractive index and high internal transmittance. Background Art

[0002] As the next generation of wearable displays, AR glasses are attracting much attention. In addition, it has been proposed to use a glass substrate in the lens portion of AR glasses.

[0003] Such a glass substrate for AR glasses is required to have a high refractive index as a light guide member and a high internal transmittance with respect to visible light.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2019 / 082616 Summary of the invention

[0007] It is difficult to say that AR glasses have become widely popular at present. One of the reasons is that AR glasses are still expensive devices. In order to further popularize AR glasses, it is necessary to further reduce the manufacturing cost.

[0008] From this point of view, the glass substrate used in the lens part of AR glasses is also expected to be low-cost. In addition, in order to meet such needs, it is considered to suppress manufacturing costs by increasing the size of the glass wafer as the basis of the glass substrate (for example, a radius of 75 mm or more).

[0009] However, it is not easy to make a glass wafer with a high refractive index and high internal transmittance large in area.

[0010] For example, glass wafers are manufactured by cooling molten glass and molding it. However, when cooling and molding high-refractive-index glass, there is a problem of crystallization occurring in the glass during the process. When crystallization occurs, the glass needs to be remelted to remove the crystals, and such remelting reduces the yield and becomes a factor in increasing costs.

[0011] In addition, generally speaking, platinum ions sometimes intrude as contaminant components during the melting of glass raw materials. Such platinum ions have an adverse effect on internal transmittance. In order to suppress the adverse effects of platinum ions, it is necessary to control the valence of platinum ions by heat treatment. However, there is a problem that such re-heat treatment causes the fictive temperature of the glass to drop.

[0012] Here, the fictive temperature (Tf) of glass is an index indicating the quasi-thermal equilibrium state (stable structure) at which the glass structure corresponds to a certain temperature. The stable structure of glass changes according to the cooling conditions, so when the cooling start temperature and the cooling rate change, the fictive temperature Tf of the obtained glass changes. In addition, relatively speaking, the lower the fictive temperature Tf of glass, the greater the specific gravity, and the brittleness of the glass tends to increase.

[0013] Therefore, when the above-mentioned reheat treatment is performed, the fictive temperature Tf of the glass decreases, resulting in a problem that the brittleness of the glass increases.

[0014] In particular, glass substrates for AR glasses with a high refractive index are often notched at the ends for the purpose of position confirmation when handling the glass substrate in the production of optical components and position adjustment (alignment adjustment) of the wafer. However, such notches are likely to become the starting point of stress concentration, so the glass substrates for AR glasses tend to be easily damaged during the process flow and handling.

[0015] Therefore, in the glass substrate for AR glasses, when the fictive temperature Tf of the glass decreases, the above-mentioned breakage problem may become more significant.

[0016] It should be noted that the above-mentioned problem is not limited to glass substrates for AR glasses, but may also occur in the entire glass substrate having a high refractive index and internal transmittance and having stress concentration portions such as notches.

[0017] The present invention has been made in view of such a background, and an object of the present invention is to provide a glass substrate with a notch which has a radius of 75 mm or more and is not easily broken.

[0018] The present invention provides a glass substrate having first and second main surfaces facing each other, and an end portion between the two main surfaces, wherein a portion of the end portion has a notch.

[0019] The specific gravity of the glass substrate is 3.00 or more.

[0020] The radius r is 75 mm or more,

[0021] Refractive index n d is 1.800 or above,

[0022] The ratio of the fictive temperature Tf (°C) to the glass transition temperature Tg (°C) (Tf / Tg) is less than 1.00,

[0023] When converted to a thickness of 10 mm, in the relationship between the internal transmittance and the wavelength, the lowest wavelength when the internal transmittance is 70% is set to λ 70 When70 Below 425nm,

[0024] In a plan view, a ratio (g / r) of a deviation g (mm) of the center of gravity G of the glass substrate from the center P of the glass substrate to a radius r is in a range of 0.05% to 1.2%.

[0025] The present invention can provide a glass substrate with a notch having a radius of 75 mm or more but being less prone to breakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a hypothetical diagram schematically showing the relationship between the wavelength and the internal transmittance (value converted to a thickness of 10 mm) of two types of transparent members.

[0027] Figure 2 It is a plan view schematically showing an example of a glass substrate according to one embodiment of the present invention.

[0028] Figure 3 This is a side view schematically showing the state of the end portion of the glass substrate according to one embodiment of the present invention.

[0029] Figure 4 This is a side view schematically showing the state of a first chamfered surface at the end of a glass substrate according to one embodiment of the present invention.

[0030] Figure 5 This is an enlarged view schematically showing a notch provided in a glass substrate according to one embodiment of the present invention. DETAILED DESCRIPTION

[0031] An embodiment of the present invention is described below.

[0032] In one embodiment of the present invention, there is provided a glass substrate having first and second main surfaces facing each other, and an end portion between the two main surfaces, wherein a portion of the end portion has a notch,

[0033] The specific gravity is 3.00 or more,

[0034] The radius r is 75 mm or more,

[0035] Refractive index n d is 1.800 or above,

[0036] The ratio of the fictive temperature Tf (°C) to the glass transition temperature Tg (°C) (Tf / Tg) is less than 1.00,

[0037] When converted to a thickness of 10 mm, in the relationship between the internal transmittance and the wavelength, the lowest wavelength when the internal transmittance is 70% is set to λ70 When 70 Below 425nm,

[0038] In a plan view, a ratio (g / r) of a deviation g (mm) of the center of gravity G of the glass substrate from the center P of the glass substrate to a radius r is in a range of 0.05% to 1.2%.

[0039] The glass substrate according to one embodiment of the present invention has a refractive index n of 1.800 or more. d . Refractive index n d For example, it may be 1.820 or more, or 1.850 or more, or 1.900 or more, or 1.940 or more, or 1.960 or more, or 2.000 or more.

[0040] It should be noted that in this application, the refractive index n d It represents the refractive index of helium at the d line (wavelength 587.6nm).

[0041] The specific gravity of the first glass substrate is 3.00 or more, for example, in the range of 3.10 to 6.80, preferably in the range of 3.40 to 6.60, more preferably in the range of 3.50 to 6.40, further preferably in the range of 3.60 to 6.30, further preferably in the range of 4.00 to 6.22, further preferably in the range of 4.30 to 6.15.

[0042] In addition, the glass substrate according to one embodiment of the present invention has a wavelength λ as specified above. 70 It is a feature below 425nm.

[0043] Below, refer to Figure 1 The above-mentioned features are described.

[0044] Figure 1 This is a hypothetical diagram schematically showing the relationship between the wavelength and the internal transmittance (value converted to a thickness of 10 mm) of two types of transparent members (a and b). Figure 1 In the figure, curve (a) is the internal transmittance curve of the first transparent component, and curve (b) is the internal transmittance curve of the second component.

[0045] like Figure 1 As shown in (b), it can be said that the internal transmittance of the second transparent component to visible light, especially blue light, is not very high. Figure 1 As shown in (a), the first transparent member has a higher internal transmittance to blue light and a higher transmittance to the entire visible light than the second transparent member.

[0046] Here, if according to Figure 1 Find the wavelength when the internal transmittance of the first transparent member is 70%, that is, λ70 (a), and the wavelength when the internal transmittance of the second transparent member is 70%, i.e., λ 70 (b), then λ 70 (a)≤425nm, and λ 70 (b)>425nm.

[0047] From this we can know whether λ is satisfied 70 ≤425nm is used to judge the quality of the component's internal transmittance to visible light.

[0048] A glass substrate according to one embodiment of the present invention satisfies λ 70 ≤425nm. Therefore, it can be said that the internal transmittance to visible light is high.

[0049] According to the above-mentioned features, the glass substrate according to one embodiment of the present invention can be used as a substrate requiring a high refractive index n. d and components with high internal visible light transmittance, such as glass substrates for AR glasses.

[0050] As a method for increasing the transmittance of glass, for example, Japanese Patent No. 6283512 describes a method for obtaining high-transmittance glass by heat treatment in an oxidizing atmosphere, in which the fictive temperature of the glass is lowered. As described above, since the fictive temperature Tf of the glass affects the brittleness of the glass, the lower the fictive temperature Tf, the higher the brittleness of the glass tends to be. Therefore, the high-refractive index glass that tends to become brittle has a higher possibility of being broken during the flow of the manufacturing process or during handling due to the presence of a notch.

[0051] However, in the glass substrate according to one embodiment of the present invention, the ratio (g / r) of the deviation amount g (mm) of the center of gravity G from the center P to the radius r is suppressed to a range of 0.05% to 1.2%.

[0052] Therefore, in one embodiment of the present invention, when the glass substrate is subjected to operations such as rotation and rotation, the centrifugal force generated by the deviation of the center of gravity G from the center P can significantly suppress the problem of breakage of the glass substrate starting from the notch.

[0053] The glass substrate according to one embodiment of the present invention has a feature that it is not easily broken despite having a low fictive temperature Tf. Therefore, in one embodiment of the present invention, a glass substrate of a relatively large size (radius 75 mm or more) can be manufactured in a complete state.

[0054] In addition, the glass substrate according to one embodiment of the present invention can be easily enlarged, and the manufacturing cost can be suppressed. Therefore, the glass substrate according to one embodiment of the present invention can be used as a low-cost component in the lens part of AR glasses.

[0055] (Glass substrate according to one embodiment of the present invention)

[0056] Next, refer to Figure 2 The structure and features of the glass substrate according to one embodiment of the present invention will be described in more detail.

[0057] Figure 2 Schematically shows an example of a plan view of a glass substrate according to an embodiment of the present invention.

[0058] like Figure 2 As shown, a glass substrate (hereinafter referred to as a "first glass substrate") 100 according to an embodiment of the present invention has a substantially circular shape.

[0059] The first glass substrate 100 has a substantially circular first main surface 110 and a substantially circular second main surface 120 (from the bottom to the top) facing each other. Figure 1 ), and an end portion 130 between the two main surfaces 110 and 120 .

[0060] A notch 180 is formed in a portion of the end portion 130 of the first glass substrate 100 .

[0061] The radius r of the first glass substrate 100 is greater than or equal to 75 mm, for example, in the range of 75 mm to 160 mm, 85 mm to 135 mm, or 98 mm to 120 mm.

[0062] The first glass substrate 100 has a refractive index n of 1.800 or more. d In addition, the specific gravity of the first glass substrate 100 is 3.00 or more.

[0063] As described above, the first glass substrate 100 has the following characteristics: when converted to a thickness of 10 mm, in the relationship between the internal transmittance and the wavelength, the minimum wavelength λ when the internal transmittance is 70% is 70 Therefore, the first glass substrate 100 has a high internal transmittance for visible light.

[0064] In the first glass substrate 100 , the ratio (Tf / Tg) of the fictive temperature Tf (° C.) to the glass transition temperature Tg (° C.) is less than 1.00. Tf / Tg is preferably less than 0.99, more preferably less than 0.98, more preferably less than 0.97, more preferably less than 0.96, and further preferably less than 0.95.

[0065] like Figure 2As shown, the first glass substrate 100 has a center P and a center of gravity G. The distance between the center P and the center of gravity G (also referred to as "deviation g") is selected so that the value of (deviation g / radius r) is in the range of 0.05% to 1.2%. The value of g / r is preferably in the range of 0.06% to 1.0%.

[0066] By setting the value of g / r to be in the range of 0.05% to 1.2%, it is possible to significantly suppress the first glass substrate 100 from being damaged starting from the notch 180 .

[0067] The first glass substrate 100 having such characteristics is suitable for use as a substrate requiring a high refractive index n. d And glass substrates for AR glasses with high internal transmittance for visible light.

[0068] (Other Features of Glass Substrate According to One Embodiment of the Present Invention)

[0069] Next, other features of the glass substrate according to one embodiment of the present invention will be described.

[0070] It should be noted that, for the sake of clarity, the first glass substrate 100 is assumed to be a glass substrate according to one embodiment of the present invention, and its features are described. Figure 2 Reference symbols shown.

[0071] (composition)

[0072] The composition of the first glass substrate 100 is not particularly limited.

[0073] The first glass substrate 100 may be, for example, silica glass, phosphate glass, borate glass, or tellurite glass. For example, silica glass preferably contains 20 mol% or more of SiO2. For example, phosphate glass preferably contains 20 mol% or more of P2O5. For example, borate glass preferably contains 10 mol% or more of B2O3. For example, tellurite glass preferably contains 10 mol% or more of TeO2.

[0074] The first glass substrate 100 may be, for example, silica-based glass, phosphate-based glass, borate-based glass, or tellurite-based glass.

[0075] The first glass substrate 100 may contain at least one selected from TiO 2 , Nb 2 O 5 , Bi 2 O 3 , La 2 O 3 , and Gd 2 O 3 as a high refractive index component.

[0076] The total amount of TiO2, Nb2O5, Bi2O3, La2O3 and Gd2O3 is, for example, in the range of 1 mol% to 80 mol%. From the viewpoint of high refractive index, strength characteristics and manufacturing characteristics, the total amount is preferably in the range of 5 mol% to 75 mol%, more preferably in the range of 10 mol% to 70 mol%, and further preferably in the range of 15 mol% to 65 mol%.

[0077] In addition, in the first glass substrate 100, the total amount of iron, chromium, and nickel is preferably less than 8 ppm by mass ratio, more preferably less than 6 ppm by mass ratio, and further preferably less than 4 ppm by mass ratio.

[0078] By setting the total amount of iron, chromium, and nickel, which are coloring transition metals, to less than 8 ppm by mass ratio, it is possible to significantly suppress a decrease in the internal transmittance of visible light of the first glass substrate 100 .

[0079] In addition, from the viewpoint of environmental burden, it is preferred that the first glass substrate 100 contains substantially no arsenic, lead, or antimony.

[0080] (End shape)

[0081] The first glass substrate 100 has an end portion 130 in which a notch 180 is formed.

[0082] Figure 3 Schematically shows a configuration example of the side surface of the end portion 130 of the first glass substrate 100 .

[0083] like Figure 3 As shown, the end portion 130 has a side region 135 , a first chamfered surface 138 , and a second chamfered surface 139 .

[0084] It should be noted that, in the present application, the “side region” refers to the entire portion of the end portion 130 that is closer to the outer end than the first chamfered surface 138 and the second chamfered surface 139 .

[0085] The end portion 130 preferably has the following configuration.

[0086] The side region 135 and the first chamfered surface 138 have a boundary O. In other words, the first chamfered surface 138 is joined to the side region 135 at the boundary O. The first chamfered surface 138 and the first main surface 110 have a boundary S. In other words, the first chamfered surface 138 is joined to the first main surface 110 at the boundary S.

[0087] Similarly, the second chamfered surface 139 is also joined to the side surface region 135 at the boundary O2. In addition, the second chamfered surface 139 is joined to the second main surface 120 at the boundary S2.

[0088] Figure 4An enlarged view of the first chamfered surface 138 is shown in FIG.

[0089] Figure 4 2 schematically shows a shape on the upper side of the bisector L when viewed from the side of the first glass substrate 100 when a bisector L passing through the center of the thickness t of the first glass substrate 100 is drawn.

[0090] like Figure 4 As shown in FIG. 1 , when viewed from above, the direction along the first main surface 110 of the first glass substrate 100 and extending perpendicularly to the end portion 130 of the first glass substrate 100 is defined as the X axis. In addition, the thickness direction of the first glass substrate 100 is defined as the Y axis. Furthermore, the boundary O between the first chamfered surface 138 and the side region 135 is defined as the origin O of the X axis and the Y axis.

[0091] In addition, the Y-axis value of the boundary S (also referred to as “intersection S”) between the first chamfered surface 138 and the first main surface 110 is denoted by C (μm).

[0092] At this time, the end portion 130 of the first glass substrate 100 is configured so that C satisfies (t / 5)≤C≤(t / 3).

[0093] In addition, it is preferable that the first chamfered surface 138 is configured so as to be included in the region Q.

[0094] Here, the region Q represents a region surrounded by the straight line LL1 connecting the origin O and the intersection S′, the straight line y=C, and the straight line LL2 connecting the origin O and the intersection S.

[0095] Among them, the straight line LL1 is expressed by formula (1), and the straight line LL2 is expressed by formula (2).

[0096] y=(C / 20)·x (1)

[0097] y=(C / 458)·x (2)

[0098] In addition, the intersection point S' is the intersection point of the straight line LL1 and the straight line y=C, and its coordinates are represented by (X1, C). On the other hand, the intersection point S is the intersection point of the straight line LL2 and the straight line y=C, and its coordinates are represented by (X2, C). Among them, 5<X1<50, 350<X2<500.

[0099] Furthermore, the first chamfered surface 138 is preferably configured to have a profile in which the value of the Y axis monotonically increases from the origin O to the intersection S in the region Q.

[0100] When the first chamfered surface 138 is configured in this way, the stress concentration on the end 130 can be significantly reduced when the first glass substrate 100 is handled. Therefore, the possibility of the first glass substrate being damaged starting from a portion other than the notch 180 can be significantly reduced.

[0101] In the above description, a preferred shape of the first chamfered surface 138 is described. However, the second chamfered surface 139 may have such a shape instead or in addition.

[0102] In this case, when viewed from above, the direction along the second main surface 120 of the first glass substrate 100 and extending perpendicularly to the end portion 130 of the first glass substrate 100 is defined as the X axis. In addition, the thickness direction of the first glass substrate 100 is defined as the Y axis. Furthermore, the boundary O2 between the second chamfered surface 139 and the side region 135 is defined as the origin of the X axis and the Y axis.

[0103] Furthermore, when the Y-axis value of the intersection S2 of the second chamfered surface 139 and the second main surface 120 is represented by C2 (μm), the second chamfered surface 139 is configured such that C2 satisfies (t / 5)≤C2≤(t / 3).

[0104] In addition, the second chamfered surface 139 is preferably configured to be included in the region Q2.

[0105] Here, the region Q2 represents a region surrounded by the straight line LR1 connecting the origin O2 and the intersection S2 ′, the straight line y=C2 , and the straight line LR2 connecting the origin O2 and the intersection S2 .

[0106] However, the straight line LR1 is expressed by the equation (3), and the straight line LR2 is expressed by the equation (4).

[0107] y=(C2 / 20)·x (3)

[0108] y=(C2 / 458)·x (4)

[0109] In addition, the intersection point S2' is the intersection point of the straight line LR1 and the straight line y=C2, and its coordinates are represented by (X3, C2). On the other hand, the intersection point S2 is the intersection point of the straight line LR2 and the straight line y=C2, and its coordinates are represented by (X4, C2). Among them, 5<X3<50, 350<X4<500.

[0110] In addition, the second chamfered surface 139 is configured to have a profile in which the value of the Y axis monotonically increases from the origin O2 toward the intersection S2 in the region Q2.

[0111] When the second chamfered surface 139 is configured in this manner, the possibility that the first glass substrate will be damaged starting from a portion other than the notch 180 can be significantly reduced.

[0112] (Gap 180)

[0113] The first glass substrate 100 has a notch 180 .

[0114] Figure 5 A schematic enlarged view of the notch 180 is shown in FIG.

[0115] like Figure 5 As shown, the notch 180 has a notch front end 182. The radius of the notch front end 182 (hereinafter referred to as "notch front end radius R") is, for example, in the range of 1.2 mm to 3.5 mm.

[0116] The notch 180 has an opening angle A. The opening angle A is, for example, in the range of 80° to 150°, preferably in the range of 84° to 145°, more preferably in the range of 85° to 140°, further preferably in the range of 86° to 130°, and most preferably in the range of 89° to 125°.

[0117] (Other Features)

[0118] The first glass substrate 100 may have a specific elastic modulus in the range of 8 MNm / kg to 35 MNm / kg, for example, in the range of 10 MNm / kg to 30 MNm / kg, preferably in the range of 11 MNm / kg to 29 MNm / kg.

[0119] In addition, the thickness t of the first glass substrate 100 may be in the range of 0.1 mm to 1.0 mm.

[0120] Furthermore, the first main surface 110 and / or the second main surface 120 of the first glass substrate 100 may have a surface roughness (arithmetic mean roughness Ra) of 10 nm or less.

[0121] The first glass substrate 100 may have a TTV (Total Thickness Variation) of 10 μm or less. TTV represents the difference between the maximum height and the minimum height from the back surface of the sample measured when the back surface of the sample is adsorbed on a flat holding surface.

[0122] In addition, the first glass substrate 100 may have a BOW (height of the center plane of the substrate) of less than 100 μm, preferably less than 50 μm. BOW represents the height of the center plane of the sample in a free state (unfixed state) relative to the reference plane. The reference plane is the center point in the standard application area, and the distance between it and the center plane of the sample is measured.

[0123] The warpage of the first glass substrate 100 obtained from a square average surface is 100 μm or less, preferably 50 μm or less, more preferably 45 μm or less, further preferably 40 μm or less, and most preferably 35 μm or less.

[0124] Example

[0125] Hereinafter, examples of the present invention will be described. It should be noted that in the following description, Examples 1 to 15 are examples, and Examples 21 to 23 are comparative examples.

[0126] (Example 1)

[0127] The glass substrate was produced by the following method.

[0128] Glass raw materials weighed to obtain a desired glass composition are placed in a melting furnace to obtain a glass melt, and the obtained glass melt is stirred to be homogenized.

[0129] Next, the molten glass is formed in a forming mold in such a way that the desired glass block is obtained. The forming mold is made of stainless steel. Afterwards, the formed glass is conveyed by rollers and slowly cooled in a slow cooling furnace. In the slow cooling furnace, the slow cooling speed is controlled by adjusting the slow cooling temperature and the conveying speed to prevent the glass sheet from cracking. The virtual temperature Tf of the glass is determined based on the slow cooling conditions.

[0130] The obtained glass block is processed in shape, cut into a disc shape, and sliced. After the slice process, it is finely ground until it reaches a predetermined thickness. For the end face of the glass plate, the end face of the glass plate cut into a disc shape is processed by grinding with a diamond grinding wheel using a CNC (Computerized Numerical Control). Afterwards, the diamond grinding wheel is replaced with a notched grinding wheel, and the portion corresponding to the notch is processed to form a notch.

[0131] Thereafter, the main surface of the glass was polished to obtain a glass substrate having a diameter of 150 mm and a thickness of 0.5 mm.

[0132] Hereinafter, the manufactured glass substrate is referred to as a “glass substrate 1 ”.

[0133] (Example 2~Example 15)

[0134] By the same method as in Example 1, a glass substrate was produced.

[0135] In Examples 2 to 15, the raw material composition, cooling conditions, etc. were changed compared to the case of Example 1 to produce glass substrates.

[0136] Hereinafter, the manufactured glass substrates are referred to as “glass substrate 2 ” to “glass substrate 15 ”, respectively.

[0137] (Example 21)

[0138] By the same method as in Example 1, a glass substrate was produced.

[0139] However, in Example 21, the raw material composition, cooling conditions, etc. were changed compared with the case of Example 1 to produce a glass substrate.

[0140] Hereinafter, the manufactured glass substrate is referred to as a “glass substrate 21 ”.

[0141] (Example 22~Example 23)

[0142] A glass substrate was manufactured by the same method as in Example 21.

[0143] In Examples 22 and 23, the glass substrates were manufactured by changing the raw material composition, cooling conditions, etc. compared with the case of Example 21.

[0144] The manufactured glass substrates are referred to as “glass substrate 22 ” to “glass substrate 23 ”, respectively.

[0145] The compositions of the glass substrates are collectively shown in Table 1 below.

[0146]

[0147] (evaluate)

[0148] Using each of the manufactured glass substrates, various characteristics were evaluated.

[0149] Table 2 shows the evaluation results obtained for each glass substrate.

[0150]

[0151] Table 2 shows the refractive index n of each glass substrate. d ”, “Specific gravity”, “Glass transition temperature Tg”, “Imaginary temperature Tf”, “Tf / Tg”, “λ 70 ”, “Deviation g / radius r”, “Shape of the first chamfered surface”, “Shape of the second chamfered surface”, “Opening angle A of the notch”, “Notch front end radius R”, “Specific elastic modulus”, “Surface roughness Ra”, “TTV”, “BOW”, “Warping”, “Young’s modulus of elasticity E” and “Handling operability”, etc.

[0152] In each glass substrate, “refractive index n d ” was determined by the V-block method using KPR-4000.

[0153] The "fictive temperature Tf" is calculated as follows.

[0154] First, the glass substrate (eg, glass substrate 1) is cut into a size of 20 mm×20 mm×1 mm to produce a glass sheet. Next, the glass sheet is heated to a predetermined heat treatment temperature in a reducing atmosphere, maintained for 2 hours, and then rapidly cooled to room temperature.

[0155] The heat treatment was carried out by changing the heat treatment temperature to prepare four glass pieces (evaluation samples) having different thermal histories.

[0156] The refractive index n was measured for each evaluation sample. d In addition, the heat treatment temperature and the refractive index n were calculated from the four evaluation samples. d Using the obtained relationship, the refractive index n measured in the glass substrate 1 is d The corresponding heat treatment temperature is determined and is defined as the fictive temperature Tf.

[0157] The fictive temperature Tf of other glass substrates was determined in the same manner.

[0158] “λ 70 ” was evaluated using a spectrophotometer (manufactured by Hitachi High-Tech Corporation: U-4100).

[0159] “Deviation amount g / radius r” is calculated by setting the distance between the center P and the center of gravity G of the glass substrate as deviation amount g and dividing the deviation amount g by the radius r of the glass substrate.

[0160] In addition, "deviation amount g / radius r" was judged by a cross (○×). That is, when the value of deviation amount g / radius r was within 0.05% to 1.2%, it was judged as "○", and other values ​​were judged as "×".

[0161] In addition, the "shape of the first chamfered surface" and the "shape of the second chamfered surface" are judged by a cross (○×). That is, the shape of the first chamfered surface is judged as "○" when it is included in the area Q specified as above and has a contour that monotonically increases from the origin O to the intersection S, and "×" when it is otherwise. The same is true for the "shape of the second chamfered surface".

[0162] The “specific elastic modulus” of each glass substrate was calculated by dividing the Young's elastic modulus evaluated and measured by the ultrasonic pulse method by the specific gravity (density) obtained by the Archimedean method.

[0163] In addition, "surface roughness Ra" means the arithmetic mean roughness Ra measured on the first surface of each glass substrate. "Surface roughness Ra" is defined by JIS B0601 (2001). In the present application, the surface roughness Ra is measured in a 10 μm×10 μm area of ​​the glass substrate using an atomic force microscope (AFM).

[0164] "TTV" indicates the difference between the maximum thickness and the minimum thickness in the entire area of ​​the glass substrate. "TTV" is measured using a laser displacement meter or an optical interferometer.

[0165] "BOW" indicates the height of the center of the glass substrate from the reference surface. "BOW" is measured using an optical interferometer.

[0166] The "warp" of the glass substrate is measured using a laser displacement meter or an optical interferometer.

[0167] The "Young's modulus of elasticity" of the glass substrate is measured using an ultrasonic pulse method.

[0168] In addition, "handling workability" was judged by crosses (○×). That is, when cracks or cracks occurred during the handling and process flow of the glass substrate, it was judged as "×", and when it was in a perfect state, it was judged as "○".

[0169] As shown in Table 2, cracks occurred in the glass substrates during the processing operation in the glass substrates 21 to 23. On the other hand, such breakage did not occur in the glass substrates 1 to 15 even after the processing operation.

[0170] From the above results, it was confirmed that in the glass substrates 1 to 15 , cracks or fissures are unlikely to occur during handling despite the low fictive temperature Tf.

[0171] (One embodiment of the present invention)

[0172] The present invention can have the following aspects.

[0173] (Method 1)

[0174] A glass substrate is a circular glass substrate having a first and a second main surface facing each other and an end portion between the two main surfaces, wherein a portion of the end portion has a notch.

[0175] The specific gravity of the glass substrate is 3.00 or more.

[0176] The radius r is 75 mm or more,

[0177] Refractive index n d is 1.800 or above,

[0178] The ratio of the fictive temperature Tf (°C) to the glass transition temperature Tg (°C) (Tf / Tg) is less than 1.00,

[0179] When converted to a thickness of 10 mm, in the relationship between the internal transmittance and the wavelength, the lowest wavelength when the internal transmittance is 70% is set to λ 70 When 70 Below 425nm,

[0180] In a plan view, a ratio (g / r) of a deviation g (mm) of the center of gravity G of the glass substrate from the center P of the glass substrate to a radius r is in a range of 0.05% to 1.2%.

[0181] (Method 2)

[0182] The glass substrate according to the first aspect, wherein when a bisector passing through the center of the thickness t of the glass substrate is drawn, the end portion has a profile having a side surface region and a first chamfered surface above the bisector when viewed from the side of the glass substrate,

[0183] When the glass substrate is viewed from above, a direction extending along the first main surface and perpendicularly to the end portion of the glass substrate is set as the X-axis, the thickness direction of the glass substrate is set as the Y-axis, the boundary between the side region and the first chamfered surface is set as the origin O of the X-axis and the Y-axis, the boundary between the first chamfered surface and the first main surface is set as the intersection S, and the Y-axis value of the intersection S is set as C (μm), (t / 5)≤C≤(t / 3),

[0184] The first chamfered surface is included in a region Q surrounded by a straight line 1 connecting the origin O and the intersection S', a straight line y=C, and a straight line 2 connecting the origin O and the intersection S.

[0185] Wherein, the straight line 1 is represented by formula (1), and the straight line 2 is represented by formula (2).

[0186] y=(C / 20)·x (1),

[0187] y=(C / 458)·x (2),

[0188] The intersection point S' is the intersection point of the straight line 1 and the straight line y=C. The coordinates of the intersection point S' are represented by (X1, C), where 5<X1<50.

[0189] The intersection point S is the intersection point of the straight line 2 and the straight line y=C. The coordinates of the intersection point S are represented by (X2, C), where 350<X2<500.

[0190] The first chamfered surface has a profile in which the value of the Y axis increases monotonically from the origin O to the intersection S in the region Q.

[0191] (Method 3)

[0192] The glass substrate according to aspect 1 or 2, wherein an opening angle A of the notch is in a range of 80° to 150°, and a tip radius R is in a range of 1.2 mm to 3.5 mm.

[0193] (Method 4)

[0194] The glass substrate according to any one of embodiments 1 to 3, wherein the glass substrate contains at least one selected from TiO 2 , Nb 2 O 5 , Bi 2 O 3 , La 2 O 3 and Gd 2 O 3 .

[0195] (Method 5)

[0196] The glass substrate according to Embodiment 4, wherein the total amount of TiO 2 , Nb 2 O 5 , Bi 2 O 3 , La 2 O 3 and Gd 2 O 3 is in the range of 1 mol % to 80 mol %.

[0197] (Method 6)

[0198] The glass substrate according to any one of aspects 1 to 5 has a specific elastic modulus in the range of 8 MNm / kg to 35 MNm / kg.

[0199] (Method 7)

[0200] The glass substrate according to any one of aspects 1 to 6 has a thickness of 0.1 mm to 1.0 mm.

[0201] (Method 8)

[0202] The glass substrate according to any one of aspects 1 to 7, wherein the first main surface has a surface roughness (Ra) of 10 nm or less.

[0203] (Method 9)

[0204] The glass substrate according to any one of aspects 1 to 8 has a TTV of 10 μm or less.

[0205] (Method 10)

[0206] The glass substrate according to any one of aspects 1 to 9, having a BOW of 100 μm or less.

[0207] (Method 11)

[0208] The glass substrate according to any one of aspects 1 to 10, wherein the warpage obtained from the square average surface is 100 μm or less.

[0209] (Method 12)

[0210] The glass substrate according to any one of aspects 1 to 11, wherein the glass substrate does not substantially contain arsenic, lead, and antimony.

[0211] (Method 13)

[0212] The glass substrate according to any one of aspects 1 to 12, wherein the total amount of iron, chromium, and nickel in the glass substrate is less than 8 ppm by mass ratio.

[0213] This application claims priority based on Japanese Patent Application No. 2022-127386 filed on August 9, 2022, the entire contents of which are incorporated herein by reference.

[0214] Explanation of symbols

[0215] 100 No. 1 Glass Substrate

[0216] 110 1st main surface

[0217] 120 Second main surface

[0218] 130 end

[0219] 135 Side Area

[0220] 138 1st chamfered surface

[0221] 139 2nd chamfered surface

[0222] 180 Gap

[0223] 182 Notch front end

Claims

1. A glass substrate, comprising a first main surface and a second main surface facing each other, and an end portion between the two main surfaces, wherein a portion of the end portion has a notch, The specific gravity of the glass substrate is 3.00 or more. The radius r is 75mm or more, Refractive index n d is 1.800 or above, The ratio of the fictive temperature Tf to the glass transition temperature Tg, Tf / Tg, is less than 1.00, and the unit of temperature is ℃. When converted to a thickness of 10 mm, in the relationship between the internal transmittance and the wavelength, the lowest wavelength when the internal transmittance is 70% is set to λ 70 When 70 Below 425nm, In a plan view, a ratio g / r of a deviation g of the center of gravity G of the glass substrate relative to the center P of the glass substrate to a radius r is in a range of 0.05% to 1.2%, and the unit of the deviation g is mm.

2. The glass substrate according to claim 1, wherein When a bisector passing through the center of the thickness t of the glass substrate is drawn, the end portion has a profile having a side region and a first chamfered surface on the upper side of the bisector when viewed from the side of the glass substrate. When the glass substrate is viewed from above, the direction along the first main surface and extending perpendicularly to the end portion of the glass substrate is set as the X-axis, the thickness direction of the glass substrate is set as the Y-axis, the boundary between the side area and the first chamfered surface is set as the origin O of the X-axis and the Y-axis, the boundary between the first chamfered surface and the first main surface is set as the intersection S, and the Y-axis value of the intersection S is set as C, (t / 5)≤C≤(t / 3), the unit of C is μm, The first chamfered surface is included in a region Q surrounded by a straight line 1 connecting the origin O and the intersection S', a straight line y=C, and a straight line 2 connecting the origin O and the intersection S. Wherein, the straight line 1 is represented by formula (1), and the straight line 2 is represented by formula (2). y=(C / 20)·x (1), y=(C / 458)·x (2), The intersection point S' is the intersection point of the straight line 1 and the straight line y=C. The coordinates of the intersection point S' are represented by (X1, C), where 5<X1<50. The intersection point S is the intersection point of the straight line 2 and the straight line y=C. The coordinates of the intersection point S are represented by (X2, C), where 350<X2<500. The first chamfered surface has a profile in which the value of the Y axis monotonically increases from the origin O to the intersection S in the region Q.

3. The glass substrate according to claim 1 or 2, wherein: The opening angle A of the notch is in the range of 80° to 150°, and the front end radius R is in the range of 1.2 mm to 3.5 mm.

4. The glass substrate according to claim 1 or 2, wherein: The glass substrate contains at least one selected from TiO2, Nb2O5, Bi2O3, La2O3 and Gd2O3.

5. The glass substrate according to claim 4, wherein: The total amount of TiO2, Nb2O5, Bi2O3, La2O3 and Gd2O3 is in the range of 1 mol% to 80 mol%. The glass substrate according to claim 1 or 2, having a specific elastic modulus in the range of 8 MNm / kg to 35 MNm / kg. 7 . The glass substrate according to claim 1 , having a thickness of 0.1 mm to 1.0 mm.

8. The glass substrate according to claim 1 or 2, wherein: The first main surface has a surface roughness Ra of 10 nm or less. 9 . The glass substrate according to claim 1 , having a TTV of 10 μm or less. 10 . The glass substrate according to claim 1 , having a BOW of 100 μm or less.

11. The glass substrate according to claim 1 or 2, wherein: The warpage obtained from the square average surface is 100 μm or less.

12. The glass substrate according to claim 1 or 2, wherein: The glass substrate is substantially free of arsenic, lead and antimony.

13. The glass substrate according to claim 1 or 2, wherein: In the glass substrate, the total amount of iron, chromium, and nickel is less than 8 ppm by mass ratio.

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