Glass plate processing method

Abstract

This glass sheet processing method involves separating a glass sheet at a separation line that separates a main surface of the glass sheet into two regions. The processing method comprises: (1) moving a first laser beam irradiation point along the separation line so as to form a crack that extends in an oblique direction with respect to the main surface from the separation line in a cross section orthogonal to the separation line; (2) moving, after formation of the crack, a second laser beam irradiation point along the separation line so as to form a reformed part on a virtual line that extends in a direction perpendicular to the main surface toward a sheet thickness center from the tip of the crack in the cross section; and (3) applying, after formation of the reformed part, stress to the glass sheet so as to form a new crack that extends across the tip of the crack and the reformed part.

Description

[Technical field]

[0001] The present disclosure relates to a method for processing a glass sheet, and a glass sheet. [Background technology]

[0002] In Patent Documents 1 and 2, a glass sheet is separated along a separation line that separates a main surface of the glass sheet into two regions. Specifically, a laser beam irradiation point is first moved along the separation line, and a crack is formed in a cross section perpendicular to the separation line, the crack extending obliquely from the separation line to the main surface.

[0003] In Patent Document 1, the separation line intersects the periphery of the main surface at an angle, and the intersection point is the movement start point of the irradiation spot. This allows a crack to be formed in a cross section perpendicular to the separation line, extending obliquely from the separation line to the main surface.

[0004] On the other hand, in Patent Document 2, the irradiation point has an asymmetric power density distribution. The left-right direction is a direction parallel to the main surface and perpendicular to the parting line. This allows the formation of a crack that extends obliquely from the parting line to the main surface in a cross section perpendicular to the parting line.

[0005] According to Patent Documents 1 and 2, as described above, in a cross section perpendicular to the parting line, a crack is obtained that extends obliquely from the parting line to the main surface. Since an inclined surface equivalent to the chamfered surface is obtained, chamfering is not required.

[0006] On the other hand, in Patent Documents 3 and 4, laser light is focused linearly inside a glass plate to form a linear damage area. The linear damage area extends in a direction perpendicular to the main surface. If a crack is formed starting from the damage area, an edge surface extending perpendicularly from the main surface can be obtained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2015 / 098641 [Patent Document 2] International Publication No. 2014 / 058354 [Patent Document 3] Japan Special Publication No. 2019-511989 [Patent Document 4] Japanese Patent Application Publication No. 2017-185547 Summary of the Invention [Problem to be solved by the invention]

[0008] According to Patent Documents 1 and 2, as described above, in a cross section perpendicular to the parting line, a crack is formed that extends obliquely from the parting line to the main surface. Therefore, even if chamfering is not performed, an inclined surface equivalent to the chamfered surface can be obtained.

[0009] In Patent Documents 1 and 2, after a crack is formed, stress is applied to the glass plate to generate a new crack from the tip of the crack. In this case, the new crack sometimes does not extend in a direction perpendicular to the main surface.

[0010] On the other hand, according to Patent Documents 3 and 4, the linear damage extends in a direction perpendicular to the main surface. Therefore, if a crack is formed starting from the damage, an end surface extending perpendicularly from the main surface can be obtained. However, since the corner between the main surface and the end surface is perpendicular, chamfering is required.

[0011] One aspect of the present disclosure provides a technique that enables a crack to extend in a direction perpendicular to the main surface from a tip of a crack extending in a diagonal direction from the parting line to the main surface in a cross section perpendicular to the parting line of the main surface. [Means for solving the problem]

[0012] A method for processing a glass sheet according to an embodiment of the present disclosure includes separating the glass sheet at a separation line that separates a main surface of the glass sheet into two regions. The method includes the following steps: A point of irradiation of a first laser beam, which mainly causes linear absorption in the glass sheet, is moved along the parting line to form a crack extending obliquely from the parting line to the main surface in a cross section perpendicular to the parting line; After the crack is formed, a point of irradiation of a second laser beam, which mainly causes nonlinear absorption in the glass sheet, is moved along the parting line to form a modified portion on a virtual line extending from the tip of the crack to the center of the sheet thickness in a direction perpendicular to the main surface in the cross section; After the modified portion is formed, stress is applied to the glass sheet to form a new crack spanning the tip of the crack and the modified portion. Effect of the Invention

[0013] According to one aspect of the present disclosure, in a cross section of the main surface perpendicular to the parting line, a crack can extend from a tip of the crack extending from the parting line in a diagonal direction to the main surface in a direction perpendicular to the main surface. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a flowchart showing a method for processing a glass plate according to the first embodiment. [Figure 2A] FIG. 2A is a perspective view showing a first example of S1 in FIG. [Figure 2B] FIG. 2B is a perspective view showing a first example of S2 in FIG. [Figure 2C] FIG. 2C is a perspective view showing a first example of S3 in FIG. [Figure 2D] FIG. 2D is a perspective view showing a first example of S4 in FIG. [Figure 2E] FIG. 2E is a perspective view showing a first example of a glass plate obtained after S4 in FIG. [Figure 3A] FIG. 3A is a perspective view showing a second example of S3 in FIG. [Figure 3B] FIG. 3B is a perspective view showing a second example of S4 in FIG. [Figure 4A] FIG. 4A is a cross-sectional view showing a third example of S3 in FIG. [Figure 4B] FIG. 4B is a cross-sectional view showing a third example of S4 in FIG. [Diagram 5] FIG. 5 is a flowchart showing a method for processing a glass plate according to the second embodiment. [Figure 6A] FIG. 6A is a perspective view showing S3 in FIG. [Figure 6B] FIG. 6B is a perspective view showing S4 in FIG. [Figure 6C] FIG. 6C is a perspective view showing the glass plate obtained after S4 in FIG. [Figure 6D] FIG. 6D is a perspective view showing S5 in FIG. [Figure 6E] FIG. 6E is a perspective view showing the glass plate obtained after S5 in FIG. [Figure 7] FIG. 7 is a flowchart showing a method for processing a glass plate according to the third embodiment. [Figure 8] FIG. 8 is a flowchart showing S6 in FIG. [Figure 9A] FIG. 9A is a plan view showing S2 in FIG. [Figure 9B] FIG. 9B is a cross-sectional view taken along line IXB-IXB in FIG. 9A. [Figure 9C] FIG. 9C is a cross-sectional view showing S3 in FIG. [Figure 9D] FIG. 9D is a cross-sectional view showing S6 in FIG. 7, specifically S61 in FIG. [Figure 9E] FIG. 9E is a cross-sectional view showing S6 in FIG. 7, specifically S62 in FIG. [Figure 9F] FIG. 9F is a cross-sectional view showing S6 in FIG. 7, specifically S63 in FIG. [Figure 9G] FIG. 9G is a cross-sectional view showing an example of S4 in FIG. [Figure 9H] FIG. 9H is a cross-sectional view showing the glass plate obtained after S4 of FIG. 7, taken along line IXH-IXH of FIG. 9I. [Figure 9I] FIG. 9I is a plan view showing the glass plate obtained after S4 in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations are denoted by the same reference numerals, and descriptions thereof may be omitted. In the specification, the symbol "~" indicating a numerical range means that the numerical values ​​before and after the symbol are included as the lower and upper limits.

[0016] (First embodiment) As shown in Fig. 1, the method for processing a glass plate includes steps S1 to S4. Hereinafter, a first example of steps S1 to S4 in Fig. 1 will be described with reference to Figs. 2A to 2E.

[0017] First, in S1 of Fig. 1, a glass plate 10 is prepared as shown in Fig. 2A. The glass plate 10 may be a curved plate, but is a flat plate in this embodiment. The glass plate 10 has a first main surface 11 and a second main surface 12 facing opposite to the first main surface 11.

[0018] The first main surface 11 and the second main surface 12 have, for example, a rectangular shape. Note that the shapes of the first main surface 11 and the second main surface 12 may be trapezoidal, circular, elliptical, or the like, and are not particularly limited.

[0019] The glass plate 10 is used, for example, as automobile window glass, cover glass for automobile interior parts such as instrument panels, head-up displays (HUD), dashboards, center consoles, and shift knobs, architectural window glass, display substrates, or display cover glass. The thickness of the glass plate 10 is appropriately set depending on the application of the glass plate 10, and is, for example, 0.01 cm to 2.5 cm.

[0020] The glass plate 10 may be laminated with another glass plate via an interlayer film after steps S1 to S4 in Fig. 1 and used as laminated glass. Furthermore, the glass plate 10 may be subjected to a tempering treatment after steps S1 to S4 in Fig. 1 and used as tempered glass.

[0021] The glass plate 10 is, for example, soda lime glass, non-alkali glass, or glass for chemical strengthening. The glass for chemical strengthening is used as, for example, a cover glass after being subjected to a chemical strengthening treatment. The glass plate 10 may be glass for air-cooling strengthening.

[0022] The glass sheet 10 may be bent after steps S1 to S4 in FIG.

[0023] Next, in S2 of Fig. 1, as shown in Fig. 2B, the irradiation point of the first laser beam LB1 is moved along the first separation line BL1 to form a first crack CR1. The first separation line BL1 separates the first main surface 11 into two regions. The first crack CR1 extends obliquely from the first separation line BL1 to the first main surface 11 in a cross section perpendicular to the first separation line BL1.

[0024] When the first crack CR1 is formed, a second crack CR2 is also formed. The second crack is formed along the second separation line BL2. The second separation line BL2 separates the second main surface 12 into two regions. The second crack CR2 extends from the second separation line BL2 in a diagonal direction relative to the second main surface 12 in a cross section perpendicular to the second separation line BL2.

[0025] The first laser beam LB1 passes through the glass plate 10 from the irradiation point on the first main surface 11 to the irradiation point on the second main surface 12. The first crack CR1 and the second crack CR2 are simultaneously formed by thermal stress of the glass. As a method for forming them, for example, the method described in Patent Document 1 or Patent Document 2 is used.

[0026] In this embodiment, both the first crack CR1 and the second crack CR2 are generated simultaneously by the irradiation of the first laser light LB1, but only one of them may be generated. In that case, the first crack CR1 and the second crack CR2 may be generated in order. However, only one of the first crack CR1 and the second crack CR2 may be generated, and the other may not be generated.

[0027] The first laser light LB1 mainly causes linear absorption when irradiated onto the glass plate 10. Mainly linear absorption means that the amount of heat generated by linear absorption is greater than the amount of heat generated by nonlinear absorption. There may be almost no nonlinear absorption. The heat generated by the first laser light LB1 forms the first crack CR1 and the second crack CR2.

[0028] Nonlinear absorption is also called multiphoton absorption. The probability of multiphoton absorption occurring is nonlinear with respect to the photon density (power density of the first laser light LB1), and the higher the photon density, the higher the probability becomes. For example, the probability of two-photon absorption occurring is proportional to the square of the photon density. If the photon density at any position on the glass plate 10 is 1×10 8 W / cm 2 In this case, very little nonlinear absorption occurs.

[0029] On the other hand, linear absorption is also called one-photon absorption. The probability of one-photon absorption occurring is proportional to the photon density. In the case of one-photon absorption, the following formula (1) holds according to the Lambert-Beer's law. I=I 0 ×exp(-α×L) (1) In the above formula (1), I0 is the intensity of the first laser light LB1 at the first main surface 11, I is the intensity of the first laser light LB1 at the second main surface 12, L is the propagation distance of the first laser light LB1 from the first main surface 11 to the second main surface 12, and α is the absorption coefficient of the glass for the first laser light LB1. α is the absorption coefficient of linear absorption and is determined by the wavelength of the first laser light LB1, the chemical composition of the glass, etc.

[0030] α×L represents the internal transmittance. The internal transmittance is the transmittance when it is assumed that the first laser light LB1 is not reflected by the first main surface 11. The smaller α×L is, the higher the internal transmittance is. α×L is, for example, 3.0 or less, more preferably 2.3 or less, and even more preferably 1.6 or less. In other words, the internal transmittance is, for example, 5% or more, preferably 10% or more, and more preferably 20% or more. If α×L is 3.0 or less, the internal transmittance is 5% or more, and both the first main surface 11 and the second main surface 12 are sufficiently heated.

[0031] From the viewpoint of heating efficiency, α×L is preferably 0.002 or more, more preferably 0.01 or more, and even more preferably 0.02 or more. In other words, the internal transmittance is preferably 99.8% or less, more preferably 99% or less, and even more preferably 98% or less.

[0032] If the temperature of the glass exceeds the annealing point, the plastic deformation of the glass is likely to progress, and the generation of thermal stress is limited. Therefore, the light wavelength, output, beam diameter at the first main surface 11, etc. are adjusted so that the temperature of the glass is below the annealing point.

[0033] The first laser light LB1 is, for example, a continuous wave light. The light source of the first laser light LB1 is, but is not limited to, a Yb fiber laser. The Yb fiber laser is an optical fiber core doped with Yb, and outputs a continuous wave light with a wavelength of 1070 nm.

[0034] However, the first laser light LB1 does not have to be continuous wave light, and may be pulsed light.

[0035] The first laser beam LB1 is irradiated onto the first main surface 11 by an optical system including a condenser lens. By moving the irradiation point along the first separation line BL1, a first crack CR1 is formed along the entire first separation line BL1. At that time, a second crack CR2 is formed along the entire second separation line BL2.

[0036] For example, a 2D galvanometer scanner or a 3D galvanometer scanner is used to move the irradiation point. The irradiation point may be moved by moving or rotating a stage that holds the glass plate 10. For example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage is used as the stage. The X-axis, the Y-axis, and the Z-axis are mutually orthogonal, the X-axis and the Y-axis are parallel to the first main surface 11, and the Z-axis is perpendicular to the first main surface 11.

[0037] Next, in S3 of Fig. 1, as shown in Fig. 2C, the irradiation point of the second laser light LB2 is moved along the first separation line BL1 to form a modified region D. The modified region D is formed on a virtual line VL of a cross section perpendicular to the first separation line BL1. The virtual line VL extends in a direction perpendicular to the first main surface 11 from the tip of the first crack CR1 toward the center of the plate thickness. The virtual line VL extends in a direction perpendicular to the first main surface 11 from the tip of the first crack CR1 to the tip of the second crack CR2.

[0038] The second laser light LB2 is a pulsed light, and forms the modified portion D by nonlinear absorption. The pulsed light is preferably a pulsed laser light having a wavelength range of 250 nm to 3000 nm and a pulse width of 10 fs to 1000 ns. Since the laser light having a wavelength range of 250 nm to 3000 nm transmits the glass plate 10 to a certain extent, the modified portion D can be formed by causing nonlinear absorption inside the glass plate 10. The wavelength range is preferably 260 nm to 2500 nm. Moreover, if the pulsed laser light has a pulse width of 1000 ns or less, the photon density can be easily increased, and the modified portion D can be formed by causing nonlinear absorption inside the glass plate 10. The pulse width is preferably 100 fs to 100 ns. The second laser light LB2 may be a pulsed light that simultaneously forms multiple focusing points in the optical axis direction by a multi-focus optical system.

[0039] The modified portion D is a portion in which the density or refractive index of the glass has changed. The modified portion D is a void, a modified layer, or the like. The modified layer is a layer in which the density or refractive index has changed due to a structural change or due to melting and resolidification.

[0040] The second laser light LB2 is, for example, focused linearly inside the glass plate 10 to linearly form the modified portion D. The light source of the second laser light LB2 may output a pulse group called a burst. One pulse group has a plurality of pulse lights (for example, 3 to 50), and each pulse light has a pulse width of less than 10 nanoseconds. In one pulse group, the energy of the pulse light may gradually decrease.

[0041] The pulsed light may be focused linearly by self-focusing due to the nonlinear Kerr effect. The pulsed light may be focused linearly in the optical axis direction by an optical system. As a specific optical system, for example, an Axicon lens is used.

[0042] The pulsed light generates a modified region D. The modified region D is formed over the entire plate thickness direction from the first main surface 11 to the second main surface 12. As will be described again later, the modified region D may be formed only in a portion of the plate thickness direction, for example, only on the first main surface 11 side with respect to the plate thickness center.

[0043] The light source of the second laser light LB2 may include, for example, a Nd-doped YAG crystal (Nd:YAG) and output a pulsed light having a wavelength of 1064 nm. The wavelength of the pulsed light is not limited to 1064 nm. An Nd;YAG second harmonic laser (wavelength 532 nm) or an Nd;YAG third harmonic laser (wavelength 355 nm) may also be used.

[0044] The second laser light LB2 is irradiated onto the first main surface 11 by an optical system including a condenser lens and the like. By moving the irradiation point along the first separation line BL1, a modified region D is formed along the entire first separation line BL1. At that time, the modified region D is formed along the entire second separation line BL2.

[0045] For example, a 2D galvanometer scanner or a 3D galvanometer scanner is used to move the irradiation point. The irradiation point may be moved by moving or rotating a stage that holds the glass plate 10. For example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage is used as the stage.

[0046] Next, in S4 of Fig. 1, as shown in Fig. 2D, stress is applied to the glass plate 10 to form a third crack CR3 that spans the tip of the first crack CR1 and the modified portion D. The third crack CR3 spans the tip of the first crack CR1 and the tip of the second crack CR2.

[0047] In forming the third crack CR3, for example, the irradiation point of the first laser beam LB1 is moved again along the first separation line BL1 to apply thermal stress to the glass plate 10. Note that a roller may be moved along the first separation line BL1 while being pressed against the glass plate 10 to apply stress to the glass plate 10.

[0048] According to the first example, before the third crack CR3 is formed, the modified portion D is formed on the imaginary line VL. The imaginary line VL extends perpendicular to the first main surface 11 and the second main surface 12, unlike the extension line of the first crack CR1 and the extension line of the second crack CR2. The modified portion D guides the third crack CR3 to the imaginary line VL. Therefore, the third crack CR3 can be generated from the tip of the first crack CR1 and the second crack CR2 in a direction perpendicular to the first main surface 11 and the second main surface 12.

[0049] After S4 in Fig. 1, a glass plate 10 as shown in Fig. 2E is obtained. The glass plate 10 has a first main surface 11, a second main surface 12, a first inclined surface 13, a second inclined surface 14, and an end surface 15. The second main surface 12 faces opposite to the first main surface 11.

[0050] The first inclined surface 13 corresponds to a so-called chamfered surface, and intersects with the first main surface 11 at an obtuse angle in a cross section perpendicular to the periphery of the first main surface 11. The interior angle between the first inclined surface 13 and the first main surface 11 is an obtuse angle. The exterior angle θ1 between the first inclined surface 13 and the first main surface 11 is, for example, 20° to 80°, and preferably 30° to 60°.

[0051] On the other hand, the second inclined surface 14 intersects with the second main surface 12 at an obtuse angle in a cross section perpendicular to the periphery of the second main surface 12. The interior angle between the second inclined surface 14 and the second main surface 12 is an obtuse angle. The exterior angle θ2 between the second inclined surface 14 and the second main surface 12 is, for example, 20° to 80°, and preferably 30° to 60°.

[0052] The first inclined surface 13 is generated by the first crack CR1. The first crack CR1 extends in the direction of movement of the irradiation point of the first laser light LB1 as the irradiation point moves. Therefore, the first inclined surface 13 includes Wallner lines or arrest lines. "Wallner lines" are striped lines that indicate the direction of crack extension. "Arrest lines" are striped lines that indicate a pause in the extension of the crack. Note that the second inclined surface 14 also includes Wallner lines or arrest lines, similar to the first inclined surface 13.

[0053] From the viewpoint of improving the fracture strength of the glass plate 10, the arithmetic mean roughness Ra of the first inclined surface 13 is, for example, less than 0.1 μm, preferably 50 nm or less, and more preferably 10 nm or less. The arithmetic mean roughness Ra of the first inclined surface 13 is, for example, 1 nm or more, preferably 2 nm or more. The arithmetic mean roughness Ra is measured in accordance with the Japanese Industrial Standard JIS B0601:2013. The arithmetic mean roughness Ra of the second inclined surface 14 is also similar to the arithmetic mean roughness Ra of the first inclined surface 13. If the arithmetic mean roughness Ra of the first inclined surface 13 and / or the arithmetic mean roughness Ra of the second inclined surface 14 of the glass plate 10 are in the above range, the fracture strength of the glass plate 10 is improved, which is particularly preferable when the glass plate 10 is used as an automobile window glass or a cover glass for an automobile interior part.

[0054] End surface 15 extends from each tip of first inclined surface 13 and second inclined surface 14 in a direction perpendicular to first main surface 11. Here, "direction perpendicular to first main surface 11" means a direction forming an angle of 10° or less with respect to the normal to first main surface 11.

[0055] The end surface 15 is generated by the third crack CR3 and coincides with the imaginary line VL. The imaginary line VL is a straight line in a cross section perpendicular to the periphery of the first main surface 11, but may be a rounded curve as described later.

[0056] Since the end surface 15 includes the modified portion D formed on the virtual line VL, it has a larger arithmetic mean roughness Ra than the first inclined surface 13 and the second inclined surface 14. The arithmetic mean roughness Ra of the end surface 15 is, for example, 0.1 μm or more, preferably 0.2 μm or more. When the arithmetic mean roughness Ra of the end surface 15 is 0.1 μm or more, slippage can be suppressed when the end surface 15 is gripped. The arithmetic mean roughness Ra of the end surface 15 is, for example, 5 μm or less, preferably 3 μm or less.

[0057] Next, a second example of S3 and S4 in Fig. 1 will be described with reference to Fig. 3A and Fig. 3B. Note that the glass plate 10 obtained after S4 in the second example is similar to the glass plate 10 obtained after S4 in the first example, and is therefore not shown. Below, differences from the first example will be mainly described.

[0058] 1, as shown in Fig. 3A, the second laser light LB2 may be focused into a dot shape inside the glass plate 10 to form a dot-like modified region D. The light source of the second laser light LB2 outputs a single pulse light or a pulse group.

[0059] The light wavelength, pulse width, etc. are adjusted so that multiphoton absorption occurs only in the vicinity of the focal point.

[0060] The light source of the second laser light LB2 may include, for example, a Nd-doped YAG crystal (Nd:YAG) and output a pulsed light having a wavelength of 1064 nm. The wavelength of the pulsed light is not limited to 1064 nm. An Nd;YAG second harmonic laser (wavelength 532 nm) or an Nd;YAG third harmonic laser (wavelength 355 nm) may also be used.

[0061] The second laser light LB2 is focused into a point shape by an optical system including a focusing lens and the like. The modified portions D are arranged in a dispersed manner by repeating two-dimensional movement of the focusing point within a plane having a constant depth from the first main surface 11 and change of the depth of the focusing point from the first main surface 11. For example, a 3D galvanometer scanner is used to move the focusing point. When the depth of the focusing point is changed by moving a stage, a 2D galvanometer scanner may be used.

[0062] The stage holds the glass plate 10. The movement of the focal point may be performed by moving or rotating the stage holding the glass plate 10. As the stage, for example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage is used. The X-axis, the Y-axis, and the Z-axis are mutually orthogonal, the X-axis and the Y-axis are parallel to the first main surface 11, and the Z-axis is perpendicular to the first main surface 11.

[0063] The modified region D is formed over the entire thickness direction from the tip of the first crack CR1 to the tip of the second crack CR2. As will be described later, the modified region D may be formed only in a part of the thickness direction, for example, may be formed only on the first main surface 11 side with respect to the center of the thickness direction.

[0064] Next, in S4 of Fig. 1, as shown in Fig. 3B, stress is applied to the glass plate 10 to form a third crack CR3 that spans the tip of the first crack CR1 and the modified portion D. The third crack CR3 spans the tip of the first crack CR1 and the tip of the second crack CR2.

[0065] According to the second example, similarly to the first example, before the third crack CR3 is formed, the modified portion D is formed on the imaginary line VL. The modified portion D guides the third crack CR3 to the imaginary line VL. Therefore, the third crack CR3 can be generated from the tip of the first crack CR1 and the second crack CR2 in a direction perpendicular to the first main surface 11 and the second main surface 12.

[0066] Next, a third example of S3 and S4 in Fig. 1 will be described with reference to Fig. 4A and Fig. 4B. Below, differences from the first and second examples will be mainly described.

[0067] In S3 of Fig. 1, as shown in Fig. 4A, the virtual line VL is a rounded curve. The angle between the tangent of the curve and the normal to the first main surface 11 may be 10° or less. A plurality of modified regions D are arranged on the virtual line VL.

[0068] Next, in S4 of Fig. 1, as shown in Fig. 4B, stress is applied to the glass plate 10 to form a third crack CR3 that spans the tip of the first crack CR1 and the modified portion D. The third crack CR3 spans the tip of the first crack CR1 and the tip of the second crack CR2.

[0069] According to the third example, similarly to the first example, before the third crack CR3 is formed, the modified portion D is formed on the imaginary line VL. The modified portion D guides the third crack CR3 to the imaginary line VL. Therefore, the third crack CR3 can be generated from the tip of the first crack CR1 and the second crack CR2 in a direction perpendicular to the first main surface 11 and the second main surface 12.

[0070] Second embodiment Incidentally, as shown in Fig. 5, the glass plate processing method may further include S5 in addition to S1 to S4. S3 to S5 in Fig. 5 will be described below with reference to Fig. 6A to Fig. 6E. Note that S1 to S2 in Fig. 5 are the same as S1 to S2 in Fig. 1, and therefore description thereof will be omitted.

[0071] 5, the second laser light LB2 is focused into a dot shape inside the glass plate 10 to form a dot-like modified region D, as shown in Fig. 6A. The modified region D is formed only on the first main surface 11 side with respect to the center of the thickness of the glass plate 10.

[0072] Next, in S4 of Fig. 5, as shown in Fig. 6B, stress is applied to the glass plate 10 to form a third crack CR3 spanning the tip of the first crack CR1 and the modified portion D. The third crack CR3 spans the tip of the first crack CR1 and the tip of the second crack CR2.

[0073] After S4 in Fig. 5, the glass plate 10 shown in Fig. 6C is obtained. The glass plate 10 has a first main surface 11, a second main surface 12, a first inclined surface 13, a second inclined surface 14, and an end surface 15. From the viewpoint of surface roughness Ra, the end surface 15 is divided into a first end surface portion 151 on the first main surface 11 side and a second end surface portion 152 on the second main surface 12 side with respect to the center of the plate thickness.

[0074] The first end surface portion 151 includes a modified portion D. Therefore, the arithmetic mean roughness Ra of the first end surface portion 151 is, for example, 0.1 μm or more, and preferably 0.2 μm or more. The arithmetic mean roughness Ra of the first end surface portion 151 is, for example, 5 μm or less, and preferably 3 μm or less.

[0075] On the other hand, the second end surface portion 152 does not include the modified portion D. Therefore, the arithmetic mean roughness Ra of the second end surface portion 152 is, for example, less than 0.1 μm, preferably 50 nm or less, and more preferably 10 nm or less. The arithmetic mean roughness Ra of the second end surface portion 152 is, for example, 1 nm or more, and preferably 2 nm or more.

[0076] 5, as shown in FIG 6D, the first inclined surface 13 is ground with a grindstone 20. This allows the first inclined surface 13 to be roughened. The grindstone 20 is a truncated cone symmetrical about a rotation axis 21, and moves along the periphery of the first main surface 11 while rotating about the rotation axis 21.

[0077] The average particle size D50 of the abrasive grains of the grindstone 20 is, for example, 20 μm to 40 μm, and preferably 10 μm to 20 μm. D50 is the particle size corresponding to a cumulative number of 50% in the particle size distribution. The particle size distribution is measured by a laser diffraction type particle size distribution meter.

[0078] After S5 in Fig. 5, the glass plate 10 shown in Fig. 6E is obtained. The glass plate 10 has a first main surface 11, a second main surface 12, a first inclined surface 13, a second inclined surface 14, and an end surface 15. The end surface 15 includes a first end surface portion 151 on the first main surface 11 side and a second end surface portion 152 on the second main surface 12 side, based on the center of the plate thickness.

[0079] The first inclined surface 13 is roughened by a grindstone 20. Therefore, the arithmetic mean roughness Ra of the first inclined surface 13 is, for example, 0.1 μm or more, preferably 0.2 μm or more. The arithmetic mean roughness Ra of the first inclined surface 13 is, for example, 5 μm or less, preferably 3 μm or less.

[0080] On the other hand, the second inclined surface 14 is not roughened by the grindstone 20. Therefore, the arithmetic mean roughness Ra of the second inclined surface 14 is, for example, less than 0.1 μm, preferably 50 nm or less, and more preferably 10 nm or less. The arithmetic mean roughness Ra of the second inclined surface 14 is, for example, 1 nm or more, and preferably 2 nm or more.

[0081] The side surface of glass plate 10 shown in Fig. 6E is divided into a rough surface 101 having a surface roughness Ra of 0.1 µm or more and a mirror surface 102 having a surface roughness Ra of less than 0.1 µm, based on the center of the plate thickness. Rough surface 101 includes a first inclined surface 13 and a first end surface portion 151 continuing from first inclined surface 13. Meanwhile, mirror surface 102 includes a second inclined surface 14 and a second end surface portion 152 continuing from second inclined surface 14. First inclined surface 13 has been roughened by grindstone 20 as described above.

[0082] Although the first inclined surface 13 is obtained by forming the first crack CR1 in S2 of Fig. 5 and then grinding in S5 of Fig. 5, it may be obtained by another method. For example, in S2 of Fig. 5, only the second crack CR2 may be formed without forming the first crack CR1. In this case, the first inclined surface 13 is obtained by grinding the perpendicular corner between the first main surface 11 and the first end surface portion 151 with a grindstone in S5 of Fig. 5.

[0083] It should be noted that the first end surface portion 151 is not ground at S5 in Fig. 5, but may be ground at S5 in Fig. 5. In the latter case, a step may be formed between the first end surface portion 151 and the second end surface portion 152.

[0084] The glass plate 10 shown in Fig. 6E is preferably used as a cover glass for an in-vehicle display. The glass plate 10 is installed inside the vehicle with the first main surface 11 facing the vehicle occupants. An anti-reflection film is formed on the first main surface 11 and the first inclined surface 13 in advance.

[0085] The anti-reflection film suppresses the reflection of light, and is, for example, a laminate of high refractive index layers and low refractive index layers having a refractive index lower than that of the high refractive index layers. The material of the high refractive index layers is, for example, niobium oxide, titanium oxide, zirconium oxide, tantalum oxide, or silicon nitride. On the other hand, the material of the low refractive index layers is, for example, silicon oxide, a mixed oxide of Si and Sn, a mixed oxide of Si and Zr, or a mixed oxide of Si and Al.

[0086] When a vehicle occupant collides with the first main surface 11, compressive stress acts on the first main surface 11 side and tensile stress acts on the second main surface 12 side, with respect to the center of the thickness of the glass plate 10. Therefore, among the side surfaces of the glass plate 10, compressive stress acts on the rough surface 101 and tensile stress acts on the mirror surface 102.

[0087] According to this embodiment, the tensile stress acts on the mirror surface 102, and therefore the strength is greater than when the tensile stress acts on the rough surface 101. This is because the mirror surface 102 has smaller irregularities that can be the starting points of destruction compared to the rough surface 101. Generally, materials are destroyed by tensile stress, not compressive stress, so even if compressive stress acts on the rough surface 101, no problem occurs.

[0088] Moreover, according to the present embodiment, the first inclined surface 13 is the rough surface 101. Therefore, compared to the case where the first inclined surface 13 is the mirror surface 102, it is possible to prevent the anti-reflection film on the first inclined surface 13 from appearing rainbow-colored due to light interference.

[0089] Third embodiment Incidentally, as shown in Fig. 7, the glass plate processing method may further include S6 in addition to S1 to S4. The timing at which S6 is performed is not limited to the timing shown in Fig. 7, and may be, for example, between S1 and S2, or between S2 and S3. S2 to S4 and S6 in Fig. 7 will be described below with reference to Figs. 9A to 9I. Since S1 in Fig. 7 is similar to S1 in Fig. 1, its description will be omitted. S5 in Fig. 5 may be performed after S4 in Fig. 7.

[0090] First, in S2 of FIG. 7, as shown in FIG. 9B, the irradiation point of the first laser light LB1 is moved along the first separation line BL1 to form a first crack CR1 and a second crack CR2.

[0091] 9A, the first separation line BL1 has a curved portion BL1a in a plan view. The second separation line BL2 also has a curved portion BL2a, similar to the first separation line BL1.

[0092] 9B, in a cross section perpendicular to the first separation line BL1, the first crack CR1 inclines toward the center of curvature C of the curved portion BL1a as the depth from the first main surface 11 increases. Similarly, in a cross section perpendicular to the second separation line BL2, the second crack CR2 inclines toward the center of curvature C as the depth from the second main surface 12 increases.

[0093] Next, in S3 of Fig. 7, as shown in Fig. 9C, the second laser light LB2 is focused into a dot shape inside the glass plate 10 to form dot-shaped modified regions D. The modified regions D are arranged on a straight virtual line VL as in the second example shown in Fig. 3A, but may be arranged on a curved virtual line VL as in the third example shown in Fig. 4A.

[0094] In S3 of Figure 7, as described above, the second laser light LB2 is focused into a point shape inside the glass plate 10 to form the modified area D in a point shape, but as in the first example shown in Figure 2C, the second laser light LB2 may be focused into a line shape to form the modified area D in a line shape.

[0095] 7, a part of the glass plate 10, for example a part including the center of curvature C of the curved portion BL1a of the first parting line BL1, is extracted by the extraction surface 17 shown in Fig. 9A. The extraction surface 17 is set between the first parting line BL1 and its center of curvature C.

[0096] 9B, the extraction surface 17 has a first intersection line 18 that intersects with the first main surface 11 and a second intersection line 19 that intersects with the second main surface 12. The first intersection line 18 has a curved portion with a center of curvature C that is the same as the first separation line BL1. The first intersection line 18 only needs to have a curved portion, and may further have a straight portion. The second intersection line 19 also has a curved portion, like the first intersection line 18.

[0097] 9A, in a plan view, the first intersection line 18 is disposed on one side of the second intersection line 19. Specifically, for example, the first intersection line 18 is disposed on the side of the center of curvature C with the second intersection line 19 as a reference. Note that the arrangement of the first intersection line 18 and the second intersection line 19 may be reversed, and the first intersection line 18 may be disposed on the opposite side of the center of curvature C with the second intersection line 19 as a reference.

[0098] As shown in FIG. 9B, in a cross section perpendicular to the first intersection line 18, the extraction surface 17 is inclined with respect to the normal N of the first main surface 11. The extraction surface 17 is, for example, a linear taper. The angle β between the normal N of the first main surface 11 and the extraction surface 17 is, for example, 3° or more. If β is 3° or more, a part of the glass sheet 10 can be extracted in the normal direction of the first main surface 11 as shown in FIG. 9F, which will be described in detail later. β is, for example, 45° or less.

[0099] In this embodiment, the extraction surface 17 is a linear taper, but may be a non-linear taper. In this case, β is the angle between the normal N of the first main surface 11 and the tangent of the extraction surface 17. It is sufficient that β is within the above range.

[0100] S6 in Fig. 7 includes S61 to S63 shown in Fig. 8. First, in S61 in Fig. 8, the second laser light LB2 is focused into a point shape inside the glass plate 10, as shown in Fig. 9D, and a point-shaped modified portion D is formed at the focused point.

[0101] The modified portions D are arranged in a dispersed manner on the extraction surface 17 by repeating two-dimensional movement of the focal point within a plane having a constant depth from the first main surface 11 and change of the depth of the focal point from the first main surface 11. For example, a 3D galvanometer scanner is used to move the focal point. When the depth of the focal point is changed by moving a stage, a 2D galvanometer scanner may be used.

[0102] The stage holds the glass plate 10. The movement of the focal point may be performed by moving or rotating the stage holding the glass plate 10. As the stage, for example, an XY stage, an XYθ stage, an XYZ stage, or an XYZθ stage is used.

[0103] The modified portion D is formed over the entire thickness direction from the first main surface 11 to the second main surface 12. Here, the entire thickness direction means a region of 80% or more of the thickness. In S62 described later, a fourth crack CR4 can be formed over the entire thickness direction.

[0104] 8, as shown in FIG 9E, stress is applied to the glass sheet 10 to form a fourth crack CR4 on the extracted surface 17. The fourth crack CR4 is formed from the modified portion D as an initiation point and extends from the first main surface 11 to the second main surface 12.

[0105] In forming the fourth crack CR4, for example, thermal stress is applied to the glass plate 10 by irradiation with the first laser beam LB1. Note that the method of applying stress to the glass plate 10 is not particularly limited. Stress may be applied to the glass plate 10 by pressing a roller against the glass plate 10.

[0106] Finally, in S63 of Fig. 8, a part of the glass plate 10, for example a part including the center of curvature C, is extracted as shown in Fig. 9F. In the extraction, the part and the remainder of the glass plate 10 are shifted in the normal direction of the first main surface 11. The part of the glass plate 10 can be extracted without breaking both the part and the remainder of the glass plate 10.

[0107] Note that, before the part and the remainder of the glass plate 10 are shifted in the normal direction of the first main surface 11, a temperature difference may be created between the part and the remainder of the glass plate 10 to form a gap between the part and the remainder of the glass plate 10. This makes it possible to prevent the glass plates from rubbing against each other.

[0108] A gap is formed if the portion on the side of the center of curvature C relative to the first intersection line 18 has a lower temperature than the portion on the opposite side of the center of curvature C. The portion on the side of the center of curvature C may be cooled, or the portion on the opposite side of the center of curvature C may be heated.

[0109] The remaining part of the glass sheet 10 is a part including the first crack CR1 and the second crack CR2. By removing a part of the glass sheet 10, the remaining part of the glass sheet 10 can be easily deformed, and subsequent processing can be easily performed.

[0110] 7, as shown in FIG 9G, stress is applied to the glass plate 10 to form a third crack CR3 that spans the tip of the first crack CR1 and the modified portion D. The third crack CR3 spans the tip of the first crack CR1 and the tip of the second crack CR2.

[0111] According to this embodiment, similarly to the first and second embodiments, before the third crack CR3 is formed, the modified region D is formed on the imaginary line VL. The modified region D guides the third crack CR3 to the imaginary line VL. Therefore, the third crack CR3 can be generated from the tip of the first crack CR1 and the second crack CR2 in a direction perpendicular to the first main surface 11 and the second main surface 12.

[0112] According to this embodiment, the first separation line BL1 has a curved portion BL1a in a plan view as shown in Fig. 9A, and a plurality of modified regions D are arranged along the curved portion BL1a. The third cracks CR3 can be guided in the arrangement direction.

[0113] According to this embodiment, as shown in Fig. 9B, in a cross section perpendicular to the first separation line BL1, the first crack CR1 inclines toward the center of curvature C of the curved portion BL1a as the depth from the first main surface 11 increases. Taking the curved portion BL1a as a reference, the portion opposite the center of curvature C (the portion to the left of the curved portion BL1a in Fig. 9A) becomes the product.

[0114] When the part on the opposite side of the center of curvature C with respect to the curved portion BL1a becomes the product, it is technically significant to arrange multiple modified portions D on the curved portion BL1a and guide the third crack CR3 in the arrangement direction. If the third crack CR3 were to extend straight in the tangent direction at a specific point on the curved portion BL1a, it would damage the product.

[0115] In order to allow the third crack CR3 to easily bend along the curved portion BL1a, the radius of curvature of the curved portion BL1a is, for example, 0.5 mm or more, preferably 1 mm or more, and is, for example, 1000 mm or less, preferably 500 mm or less.

[0116] After S4 in FIG. 7, unnecessary parts from the third crack CR3 to the fourth crack CR4 shown in FIG. 9G are removed. For example, the unnecessary parts are irradiated with laser light, and the unnecessary parts are thermally broken into a plurality of fragments and removed. As a result, the glass plate 10 shown in FIG. 9H and FIG. 9I is obtained. The glass plate 10 has a first main surface 11, a second main surface 12, a first inclined surface 13, a second inclined surface 14, and an end surface 15. Note that the removal of the unnecessary parts can also be achieved by cooling contraction instead of heating and breaking. EXAMPLES

[0117] A specific example of a method for processing a glass plate will be described below.

[0118] [Example 1] In Example 1, steps S1 to S4 in Fig. 1 were carried out. In S1, a soda lime glass plate 10 having a thickness of 1.8 mm was prepared. The first main surface 11 was a rectangle having a length of 100 mm and a width of 50 mm. The first separation line BL1 was a straight line extending from a long side of the first main surface 11 diagonally to another long side.

[0119] In S2, as shown in Fig. 2B, the irradiation point of the first laser beam LB1 was moved along the first separation line BL1 to form the first crack CR1 and the second crack CR2. A 3D galvano scanner was used to move the irradiation point.

[0120] The irradiation conditions of the first laser beam LB1 in S2 were as follows: Oscillator: Yb fiber laser (IPG Photonics, YLR500) Oscillation method: Continuous wave oscillation Light wavelength: 1070nm Output: 440W In-plane scanning speed: 70mm / s Beam diameter at first main surface 11: 0.6 mm.

[0121] In S3, as shown in Fig. 2C, the second laser light LB2 was focused linearly inside the glass plate 10 to form a linear modified region D. The irradiation point of the second laser light LB2 was moved along the first separation line BL1 to form a plurality of modified regions D at a predetermined pitch along the first separation line BL1. An XYZ stage was used to move the irradiation point.

[0122] The irradiation conditions of the second laser beam LB2 in S3 were as follows: Oscillator: Picosecond pulse laser (Rofin, StarPico3) Oscillation method: Pulse oscillation (burst) Light wavelength: 1064nm Output: 35.6W Oscillation frequency: 75kHz In-plane scanning speed: 187.5 mm / s In-plane irradiation pitch: 5μm Pulse energy: 475μJ.

[0123] In S4, as shown in FIG. 2D, stress was applied to the glass plate 10 to form a third crack CR3 spanning the tip of the first crack CR1 and the tip of the second crack CR2. In forming the third crack CR3, thermal stress was applied to the glass plate 10 by irradiating it with the first laser beam LB1. An XYZ stage was used to move the irradiation point of the first laser beam LB1. The irradiation conditions of the first laser beam LB1 in S4 were the same as those of the first laser beam LB1 in S2.

[0124] After S4, the glass plate 10 shown in Fig. 2E was obtained. The arithmetic mean roughness Ra of the first inclined surface 13, the second inclined surface 14, and the end surface 15 of the glass plate 10 was measured using a surface roughness measuring device (DektakXT, manufactured by Bruker). The measurement conditions are shown below. Cutoff value λc: 0.025mm Cutoff ratio λc / λs: 10 Measurement speed: 0.1mm / sec Evaluation length: 1.0mm.

[0125] The arithmetic mean roughness Ra of the first inclined surface 13 was 5.2 nm. The arithmetic mean roughness Ra of the second inclined surface 14 was also 5.2 nm. On the other hand, the arithmetic mean roughness Ra of the end surface 15 was 0.4 μm.

[0126] [Example 2] In Example 2, S1 to S5 in Fig. 5 were carried out. In S1, an aluminosilicate glass having a thickness of 1.3 mm was prepared as the glass plate 10. The first main surface 11 was a rectangle having a length of 100 mm and a width of 50 mm. The first separation line BL1 was a straight line extending from a long side of the first main surface 11 in an oblique direction to another long side.

[0127] In S2, as shown in Fig. 2B, the irradiation point of the first laser beam LB1 was moved along the first separation line BL1 to form the first crack CR1 and the second crack CR2. A 3D galvano scanner was used to move the irradiation point.

[0128] The irradiation conditions of the first laser beam LB1 in S2 were as follows: Oscillator: Yb fiber laser (IPG Photonics, YLR500) Oscillation method: Continuous wave oscillation Light wavelength: 1070nm Output: 440W In-plane scanning speed: 70mm / s Beam diameter at first main surface 11: 0.6 mm.

[0129] In S3, as shown in Fig. 6A, the second laser beam LB2 was focused into a point shape inside the glass plate 10 to form a point-like modified region D. The modified region D was formed only on the first main surface 11 side with respect to the center of the plate thickness of the glass plate 10. An XYZ stage was used to move the focusing point.

[0130] The irradiation conditions of the second laser beam LB2 in S3 were as follows: Oscillator: Nanosecond pulse laser (Spectra Physics, Explorer532-2Y) Oscillation method: Pulse oscillation (single) Light wavelength: 532nm Output: 2W Oscillation frequency: 10kHz In-plane scanning speed: 100mm / s In-plane irradiation pitch: 0.01 mm Depth direction irradiation pitch: 0.05 mm Focused beam diameter: 4μm Pulse energy: 200μJ.

[0131] In S4, as shown in FIG. 6B, stress was applied to the glass plate 10 to form a third crack CR3 spanning the tip of the first crack CR1 and the tip of the second crack CR2. In forming the third crack CR3, thermal stress was applied to the glass plate 10 by irradiating it with the first laser beam LB1. An XYZ stage was used to move the irradiation point of the first laser beam LB1. The irradiation conditions of the first laser beam LB1 in S4 were the same as those of the first laser beam LB1 in S2.

[0132] In S5, as shown in Fig. 6D, the first inclined surface 13 was ground and roughened with a grindstone 20. The average grain size D50 of the abrasive grains of the grindstone 20 was 40 µm.

[0133] After S5, the glass plate 10 shown in FIG. 6E was obtained. The arithmetic mean roughness Ra of the first inclined surface 13 was 0.5 μm. The arithmetic mean roughness Ra of the first end surface portion 151 of the end surface 15 was 2.1 μm. Meanwhile, the arithmetic mean roughness Ra of the second end surface portion 152 of the end surface 15 was 2.9 nm. The arithmetic mean roughness Ra of the second inclined surface 14 was 5.2 nm.

[0134] A test piece for a four-point bending test was prepared as the glass plate 10 shown in FIG. 6E, and a four-point bending test was performed. In the four-point bending test, a compressive stress was generated on the first main surface 11, and a tensile stress was generated on the second main surface 12. As a result, the breaking strength was 248 MPa. It was also confirmed that the starting point of the breakage was the second main surface 12, and not the second inclined surface 14 or the second end surface portion 152.

[0135] [Example 3] In Example 3, S1 to S4 and S6 in Fig. 7 were carried out. In S1, a soda lime glass having a thickness of 3.5 mm was prepared as the glass plate 10. The first main surface 11 was a rectangle having a length of 200 mm and a width of 150 mm. The curved portion BL1a of the first separation line BL1 was an arc having a radius of 80 mm. The angle β between the normal to the first main surface 11 and the extraction surface 17 was 4°.

[0136] In S2, as shown in Fig. 9A and Fig. 9B, the irradiation point of the first laser beam LB1 was moved along the first separation line BL1 to form the first crack CR1 and the second crack CR2. The irradiation point was moved using an XYZ stage.

[0137] The irradiation conditions of the first laser beam LB1 in S2 were as follows: Oscillator: Yb fiber laser (IPG Photonics, YLR500) Oscillation method: Continuous wave oscillation Light wavelength: 1070nm Output: 220W In-plane scanning speed: 70mm / s Beam diameter at first main surface 11: 1.2 mm.

[0138] In S3, as shown in Fig. 9C, the second laser beam LB2 was focused into a point shape inside the glass plate 10 to form a point-like modified region D. The modified regions D were distributed and arranged on the extraction surface 17 by repeatedly moving the focusing point two-dimensionally within a plane having a constant depth from the first main surface 11 and changing the depth of the focusing point from the first main surface 11. An XYZ stage was used to move the focusing point.

[0139] The irradiation conditions of the second laser beam LB2 in S3 were as follows: Oscillator: Nanosecond pulse laser (Spectra Physics, Explorer532-2Y) Oscillation method: Pulse oscillation (single) Light wavelength: 532nm Output: 2W Oscillation frequency: 10kHz In-plane scanning speed: 100 mm / s In-plane irradiation pitch: 0.01 mm Depth direction irradiation pitch: 0.05 mm Focused beam diameter: 4μm Pulse energy: 200μJ.

[0140] In S61 included in S6, as shown in FIG. 9D, the second laser beam LB2 was focused in a dot shape inside the glass plate 10, and dot-shaped modified areas D were formed at the focused points. The modified areas D were distributed and arranged on the extraction surface 17 by repeatedly moving the focused point two-dimensionally within a plane having a constant depth from the first main surface 11 and changing the depth of the focused point from the first main surface 11. An XYZ stage was used to move the focused point. The irradiation conditions of the second laser beam LB2 in S61 were the same as those of the second laser beam LB2 in S3 above.

[0141] In S62 included in S6, as shown in FIG. 9E, stress was applied to the glass plate 10 to form a fourth crack CR4 on the extraction surface 17. In forming the fourth crack CR4, thermal stress was applied to the glass plate 10 by irradiating the first laser light LB1. The first laser light LB1 was irradiated onto the first main surface 11 by an optical system including a condenser lens and the like. The irradiation point was moved along the first intersection line 18 to form the fourth crack CR4 on the entire extraction surface 17. A 3D galvano scanner was used to move the irradiation point. The irradiation conditions of the first laser light LB1 in S62 were the same as those of the first laser light LB1 in S2, except that the output was increased to 340 W.

[0142] In S63 included in S6, a part of the glass plate 10 was removed as shown in Fig. 9F. The part of the glass plate 10 was a part including the center of curvature C, and the remaining part of the glass plate 10 was a part including the first crack CR1 and the second crack CR2.

[0143] In S4, as shown in FIG. 9G, stress was applied to the glass plate 10 to form a third crack CR3 spanning the tip of the first crack CR1 and the tip of the second crack CR2. In forming the third crack CR3, thermal stress was applied to the glass plate 10 by irradiating it with the first laser beam LB1. A 3D galvano scanner was used to move the irradiation point of the first laser beam LB1. The irradiation conditions of the first laser beam LB1 in S4 were the same as those of the first laser beam LB1 in S2, except that the output was increased to 340 W.

[0144] After S4, the unnecessary parts from the third crack CR3 to the fourth crack CR4 shown in FIG. 9G were irradiated with the first laser beam LB1, and the unnecessary parts were broken into a plurality of pieces by heat and removed. The irradiation conditions of the first laser beam LB1 at that time were the same as those of the first laser beam LB1 in S2, except that the output was increased to 460 W and the scanning speed in the in-plane direction was slowed to 10 mm / s. After the unnecessary parts were broken, the glass plate 10 shown in FIG. 9H and FIG. 9I was obtained.

[0145] The above describes the glass plate processing method and the glass plate according to the present disclosure, but the present disclosure is not limited to the above-mentioned embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0146] This application claims priority based on Japanese Patent Application No. 2019-210499, filed with the Japan Patent Office on November 21, 2019, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0147] 10 Glass Plate 11 First main surface 12 Second main surface 13 1st slope 14 Second slope 15 End face 151 First end section 152 Second end section BL1 1st separation line BL1a curved part BL2 2nd separation line C center of curvature CR1 First Crack CR2 2nd Crack CR3 3rd Crack D Modification section

Claims

1. A method for processing a glass sheet, comprising: separating the glass sheet at a separation line that separates a main surface of the glass sheet into two regions, the method comprising the steps of: a first laser beam irradiation point that mainly causes linear absorption in the glass plate is moved along the separation line to form a crack that extends obliquely from the separation line to the main surface in a cross section perpendicular to the separation line; After the crack is formed, a modified portion is formed on a virtual line extending in a direction perpendicular to the main surface from the tip of the crack toward the center of the plate thickness in the cross section by moving an irradiation point of the second laser light that mainly causes nonlinear absorption in the glass plate along the separation line, a glass plate processing method comprising: applying stress to the glass plate after the modified portion is formed, thereby forming a new crack spanning the tip of the crack and the modified portion.

2. The processing method according to claim 1 , wherein the parting line includes a curved portion in a plan view.

3. The processing method according to claim 2 , wherein the radius of curvature of the curved portion is 0.5 mm or more and 1000 mm or less.

4. The processing method according to claim 2 or 3, wherein, in the cross section, the crack inclines toward a center of curvature of the curved portion as the crack becomes deeper from the main surface.

5. The processing method according to any one of claims 1 to 4, wherein the second laser light is focused linearly to form the modified portion linearly.

6. The processing method according to any one of claims 1 to 4, wherein the second laser light is focused into a dot shape, and the modified portion is formed in a dot shape.

7. The processing method according to any one of claims 1 to 6, wherein the cracks are formed in each of the two main surfaces by irradiation with the first laser light.

Images