Glass substrate, cover glass, assembly, assembly manufacturing method, in-vehicle display device, and in-vehicle display device manufacturing method

Abstract

This glass substrate comprises: a thin plate section; a thick plate section; and a connecting section. The thin plate section includes a first main surface and a second main surface opposing the first main surface. The thick plate section includes a first main surface and a second main surface opposing the first main surface. The thick plate section is thicker than the thin plate section. The connecting section includes: a first connecting surface connecting the first main surface of the thin plate section and the first main surface of the thick plate section; and a second connecting surface connecting the second main surface of the thin plate section and the second main surface of the thick plate section. The radius of curvature of the first connecting surface is 400 μm or more.

Description

[Technical field]

[0001] The present invention relates to a glass substrate, a cover glass, an assembly, a method for manufacturing an assembly, an in-vehicle display device, and a method for manufacturing an in-vehicle display device. [Background technology]

[0002] Conventionally, a glass substrate having a structure in which glass plate portions having different thicknesses are connected to each other has been used as, for example, a cover glass (FIG. 5 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 213267 Summary of the Invention [Problem to be solved by the invention]

[0004] A glass substrate having a configuration in which glass plate portions of different thicknesses are connected to each other includes a thin plate portion, a thick plate portion that is thicker than the thin plate portion, and a connecting portion that connects the thin plate portion and the thick plate portion. There is expected to be a demand for such glass substrates in which the thin plate portion is elastically deformed and assembled into a concave-convex structure. The inventors have found through their investigations that depending on the shape of the connection part of the glass base, it may be difficult to bend the connection part. In this case, there is a possibility that a defect may occur in the assembly obtained by assembling the glass base to the concave-convex structure.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a glass base in which a connection portion connecting a thin plate portion and a thick plate portion can be easily bent. [Means for solving the problem]

[0006] As a result of intensive research, the present inventors have found that the above object can be achieved by adopting the following configuration. That is, the present invention relates to the following [1] to

[11] . [1] A glass base comprising: a thin plate portion having a first main surface and a second main surface opposite the first main surface; a thick plate portion having a plate thickness t3 greater than a plate thickness t2 of the thin plate portion and having the first main surface and a second main surface opposite the first main surface; and a connecting portion having a first connecting surface connecting the first main surface of the thin plate portion to the first main surface of the thick plate portion and a second connecting surface connecting the second main surface of the thin plate portion to the second main surface of the thick plate portion, wherein the radius of curvature of the first connecting surface is 400 μm or more. [2] A glass base comprising: a thin plate portion having a first main surface and a second main surface opposite the first main surface; a thick plate portion having a thickness t3 greater than a thickness t2 of the thin plate portion and having the first main surface and a second main surface opposite the first main surface; and a connecting portion having a first connecting surface connecting the first main surface of the thin plate portion to the first main surface of the thick plate portion and a second connecting surface connecting the second main surface of the thin plate portion to the second main surface of the thick plate portion, wherein a thickness t4 of the thinnest point of the connecting portion is smaller than the thickness t2 of the thin plate portion. [3] The glass base according to [2] above, wherein the plate thickness t4 of the connecting portion is 0.5 mm or less. [4] The glass base according to any one of the above [1] to [3], wherein the thickness t2 of the thin portion is 0.05 mm or more and 0.8 mm or less, and the thickness t3 of the thick portion is 0.5 mm or more and 2.5 mm or less. [5] The glass base according to any one of the above [1] to [4], wherein the connection portion has an overhang portion. [6] The glass base according to any one of the above [1] to [5], which is a chemically strengthened glass. [7] A cover glass for covering a display panel, comprising the glass base according to any one of the above [1] to [6]. [8] An assembly comprising: a concave-convex structure; and a glass base according to any one of [1] to [6] above assembled to the concave-convex structure, wherein the thin portion of the glass base is assembled to the concave-convex structure in a state in which it is elastically deformed along the shape of the concave-convex structure. [9] A method for manufacturing an assembly, comprising assembling the glass base according to any one of [1] to [6] above into a concave-convex structure, wherein the thin plate portion of the glass base is elastically deformed to conform to the shape of the concave-convex structure, and assembled into the concave-convex structure.

[10] An in-vehicle display device having an instrument cluster arranged in front of a driver's seat, a center information display arranged in front of the driver's seat and a passenger seat, and the glass base described in any one of [1] to [6] above, wherein the instrument cluster has a concave-convex structure, and the thin plate portion of the glass base is assembled to the concave-convex structure in a state where it is elastically deformed along the shape of the concave-convex structure, and the thick plate portion of the glass base is assembled to the center information display.

[11] A method for manufacturing an in-vehicle display device, comprising assembling the glass substrate according to any one of [1] to [6] above to an instrument cluster arranged in front of a driver's seat, and to a center information display arranged in front of a passenger seat between the driver's seat and the passenger seat, wherein the instrument cluster has a concave-convex structure, and the thin plate portion of the glass substrate is elastically deformed along a shape of the concave-convex structure to be assembled to the concave-convex structure, and the thick plate portion of the glass substrate is assembled to the center information display. Effect of the Invention

[0007] According to the present invention, a glass base can be obtained in which the connection portion connecting the thin plate portion and the thick plate portion is easily bent. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a glass substrate according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing an assembly in which the glass substrate of the first embodiment is assembled into a concave-convex structure. [Diagram 3] FIG. 3 is a cross-sectional view showing a modified example of the glass base of the first embodiment. [Figure 4]FIG. 4 is a cross-sectional view showing a glass plate. [Diagram 5] FIG. 5 is a cross-sectional view showing a glass plate covered with a masking material. [Figure 6] FIG. 6 is a cross-sectional view showing the glass plate after etching. [Figure 7] FIG. 7 is a cross-sectional view showing a glass substrate according to a second embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing the glass plate after polishing. [Figure 9] FIG. 9 is a cross-sectional view showing a glass plate covered with a masking material. [Figure 10] FIG. 10 is a cross-sectional view showing the glass plate after etching. [Figure 11] FIG. 11 is a cross-sectional view for explaining how to determine the radius of curvature of the first connecting surface and the radius of curvature of the overhanging surface. [Figure 12] FIG. 12 is a cross-sectional view for explaining a method for evaluating the bendability of a connection portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment. Various modifications and substitutions can be made to the following embodiment without departing from the scope of the present invention.

[0010] Ranges expressed using "~" include both ends of the range. For example, a range expressed as "A~B" includes A and B.

[0011] The glass sheet thickness (average sheet thickness) is determined by measurement using a micrometer.

[0012] A method for determining the radius of curvature of the curved surface of the glass will be described later (with reference to FIG. 11).

[0013] The compressive stress value (CS) and the depth of the compressive stress layer (DOL) of the compressive stress layer of the glass are determined by measurement using a surface stress meter (FSM-6000) manufactured by Orihara Seisakusho Co., Ltd. The internal tensile stress (CT) of glass is calculated from CS, DOL and sheet thickness t based on the following formula. CT=CS[MPa]×DOL[mm] / (t[mm]-2×DOL[mm])

[0014] The limiting bending radius of glass is the minimum bending radius at which no cracks occur when the glass is bent, and the bending radius is determined by the following bending test. The bending test and the bending test device used in the bending test conform to the test and device described in WO 2016 / 194785. (Bending test) The first support plate and the second support plate are arranged in parallel so that the support surface of the first support plate and the support surface of the second support plate face each other. The first support plate and the second support plate support the edge of the glass, respectively. The distance between the support surface of the first support plate and the support surface of the second support plate is maintained at the distance D [mm] calculated by the following formula (1). In this state, the position of the second support plate relative to the first support plate is moved back and forth by 100 mm in a direction parallel to the support surfaces of the first support plate and the second support plate and in a direction that does not change the curvature direction of the glass. It is checked whether cracks are formed in the glass to be curved between the first support plate and the second support plate. The bending radius R is calculated by the following formula (2). D = (A × E × t / σ) + t (1) R=D / 2 (2) R / t=1 / 2(A×E / σ+1) (3) D: Distance between the support surface of the first support plate and the support surface of the second support plate [mm] A=1.198 E: Young's modulus of glass [MPa] t: Glass thickness [mm] σ: Bending stress [MPa]

[0015] The surface strength of the glass plate is determined by the ball-on-ring (BOR) test described below. (Ball-on-ring test) First, the glass plate is placed horizontally on a stainless steel ring with a diameter of 30 mm and a curvature radius of 2.5 mm at the contact point with the glass plate. Next, a steel sphere with a diameter of 10 mm is brought into contact with the glass plate placed on the ring at the center of the ring. In this state, the sphere is lowered and pressed against the glass plate (descending speed of the sphere: 1.0 mm / min), applying a static load to the glass plate and destroying it. The load at which the glass plate breaks is measured, and the average of 20 measurements is regarded as the surface strength of the glass plate. However, if the starting point of the glass plate's breakage is 2 mm or more away from the position where the sphere was pressed, this is excluded from the measurements used to calculate the average value.

[0016] [First aspect] The first embodiment will be described with reference to FIGS. First, the glass base of the first embodiment will be described with reference to FIGS.

[0017] <Glass Base> FIG. 1 is a cross-sectional view showing a glass base 1 of the first embodiment. The glass base 1 has a thin plate portion 2 , a thick plate portion 3 and a connection portion 4 . The thin plate portion 2 has a first main surface 2a and a second main surface 2b opposite to the first main surface 2a. The thick plate portion 3 has a first main surface 3a and a second main surface 3b opposite to the first main surface 3a. The plate thickness t3 of the thick plate portion 3 is greater than the plate thickness t2 of the thin plate portion 2. The connecting portion 4 has a first connecting surface 4a and a second connecting surface 4b. The first connecting surface 4a connects the first main surface 2a of the thin plate portion 2 and the first main surface 3a of the thick plate portion 3. The second connecting surface 4b connects the second main surface 2b of the thin plate portion 2 and the second main surface 3b of the thick plate portion 3. Here, in the glass base 1 of the first embodiment in a state not elastically deformed, the second main surface 2b of the thin plate portion 2, the second connecting surface 4b of the connecting portion 4, and the second main surface 3b of the thick plate portion 3 form the same plane.

[0018] FIG. 2 is a schematic diagram showing an assembly 31 in which the glass base 1 of the first embodiment is assembled with a concave-convex structure 21. As shown in FIG. The concave-convex structure 21 has, for example, a display panel 22, a display panel 23, a display panel 24, and a display panel 25, which are held by a panel holding portion 26 having a concave-convex shape. More specifically, the three display panels 22, 23 and 24 are arranged in a concave position, and one display panel 25 is arranged in a convex position. Each display panel is, for example, a liquid crystal panel. In this case, a backlight unit is disposed on the rear side of each liquid crystal panel. Each display panel may be, for example, an organic EL panel, a PDP, an electronic ink panel, or the like. Each display panel may have a touch panel, or the like.

[0019] The glass substrate 1 is assembled to such a concave-convex structure 21 . More specifically, for example, the first main surface 3a of the thick plate portion 3 of the glass base 1 is bonded to the display panel 25 via an OCA (Optical Clear Adhesive) (not shown). Furthermore, while the thin plate portion 2 of the glass base 1 is elastically deformed into a concave shape, the first main surface 2a of the elastically deformed thin plate portion 2 is bonded to the display panels 22, 23, and 24 via the OCA (not shown). That is, the thin plate portion 2 of the glass base 1 is assembled to the concave-convex structure 21 in a shape following the concave-convex structure 21 in an elastically deformed state. In this manner, the assembly 31 is obtained.

[0020] In the assembly 31, the glass base 1 functions as a cover glass that covers each display panel. That is, the cover glass is made of the glass base 1 and covers each display panel. When used as a cover glass, the glass base 1 is preferably glass that has been subjected to a chemical strengthening treatment (chemically strengthened glass).

[0021] The assembly 31 is, for example, a display device, and a specific example thereof is an in-vehicle display device that is mounted on a vehicle for use. More specifically, examples of such in-vehicle display devices include an instrument cluster (cluster) located in front of the driver's seat, and a center information display (CID) located in front of the driver's seat and passenger seat. For example, in assembly 31 which is an in-vehicle display device, the portion where display panel 22, display panel 23, and display panel 24 are arranged in a concave shape is the cluster. That is, the cluster has concave-convex structure 21. On the other hand, the portion where display panel 25 is arranged is the CID. In this case, thin plate portion 2 is used as a cover glass of the cluster, and thick plate portion 3 is used as a cover glass of the CID. In addition, the thick plate portion 3 used as the cover glass of the CID does not have a handle operated by the driver, so the head of the occupant is likely to hit it directly in the event of a vehicle collision. For this reason, it is preferable that the thick plate portion 3 has enough impact resistance to prevent it from breaking when the occupant's head hits it in the event of a vehicle collision.

[0022] Incidentally, when the thin plate portion 2 of the glass base 1 is to be elastically deformed as shown in FIG. 2, it is necessary to bend the connection portion 4 of the glass base 1. At this time, if it is difficult to bend the connection portion 4 (if the connection portion 4 is not bent sufficiently), for example, the bonding between the first main surface 2a of the thin plate portion 2 and the display panel 24 may easily peel off, which may cause problems with the assembly 31.

[0023] However, in the glass base 1, the radius of curvature r1 of the first connecting surface 4a shown in Fig. 1 is 400 µm or more, which makes it easy to bend the connecting portion 4. In addition, when a film such as OCA is attached to the first connecting surface 4a, even if air bubbles are trapped between the first connecting surface 4a and the film, the air bubbles can be easily removed. Because of these advantages, the radius of curvature r1 of the first connecting surface 4a is preferably 550 μm or more, and more preferably 700 μm or more.

[0024] On the other hand, the upper limit of the radius of curvature r1 of the first connecting surface 4a is not particularly limited, but is preferably 1300 μm or less, more preferably 1100 μm or less, and further preferably 900 μm or less.

[0025] 《Thin plate part》 The thin plate portion 2 has a first main surface 2a and a second main surface 2b. The thickness t2 of the thin plate portion 2 is preferably 0.05 mm or more, and more preferably 0.2 mm or more, whereas the thickness t2 of the thin plate portion 2 is preferably 0.8 mm or less, and more preferably 0.6 mm or less. The compressive stress value (CS) of the compressive stress layer of the thin plate portion 2 is preferably 500 MPa or more, more preferably 650 MPa or more, and even more preferably 750 MPa or more. The depth of the compressive stress layer (DOL) of the thin plate portion 2 is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 25 μm or more. The internal tensile stress (CT) of the thin plate portion 2 is preferably 160 MPa or less, more preferably 140 MPa or less, while the internal tensile stress (CT) of the thin plate portion 2 is preferably 20 MPa or more, more preferably 30 MPa or more. The limit bending radius of the thin plate portion 2 is preferably 60 mm or less, more preferably 50 mm or less, and further preferably 40 mm or less.

[0026] <Thick Plate> The thick plate portion 3 has a first main surface 3a and a second main surface 3b. The plate thickness t3 of the thick plate portion 3 is preferably 0.5 mm or more, and more preferably 0.7 mm or more. On the other hand, the plate thickness t3 of the thick plate portion 3 is preferably 2.5 mm or less, and more preferably 2.0 mm or less. If the plate thickness t3 of the thick plate portion 3 is within this range, the thick plate portion 3 has excellent impact resistance. The compressive stress value (CS) of the compressive stress layer of the thick plate portion 3 is preferably 500 MPa or more, more preferably 650 MPa or more, and even more preferably 750 MPa or more, because the thick plate portion 3 has excellent impact resistance. The depth of the compressive stress layer (DOL) of the thick plate portion 3 is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 25 μm or more, because the thick plate portion 3 has excellent impact resistance. The internal tensile stress (CT) of the thick plate portion 3 is preferably 50 MPa or less, and more preferably 30 MPa or less, because the thick plate portion 3 has excellent impact resistance. On the other hand, the internal tensile stress (CT) of the thick plate portion 3 is preferably 1 MPa or more, and more preferably 5 MPa or more.

[0027] The surface strength of the thick plate portion 3 is preferably 150 kgf or more, more preferably 200 kgf or more, and even more preferably 250 kgf or more, because the thick plate portion 3 has excellent impact resistance.

[0028] 25mm of thin plate section 2 and thick plate section 3 2 The number density (unit: pieces / (5cm x 5cm)) of the fragments having an area of ​​25 mm or more (hereinafter simply referred to as "fragments") is preferably different from each other, and more preferably has a clear difference. Here, the number density is the number of pieces per 25 mm unit area (5cm x 5cm) when the glass is broken. 2 This refers to the number of crushed pieces (hereinafter simply referred to as "crushed pieces") having an area of ​​this or more. Specifically, the difference in number density of crushed fragments between the thin plate portion 2 and the thick plate portion 3 is preferably 0.1 fragments / (5cm x 5cm) or more, more preferably 1 fragment / (5cm x 5cm) or more, even more preferably 5 fragments / (5cm x 5cm) or more, and particularly preferably 7 fragments / (5cm x 5cm) or more. If the difference in number density of the crushed pieces is within this range, the crushing will be discontinuous between the thin plate portion 2 and the thick plate portion 3, and even if the thin plate portion 2 is crushed, the spread of the crushing to the thick plate portion 3 can be reduced.

[0029] The number of crushed pieces may be greater in the thin plate portion 2 than in the thick plate portion 3. In this case, there is a technical significance in that when an impact is applied to the thin plate portion 2 and the thin plate portion 2 is crushed, the propagation of cracks from the thin plate portion 2 to the thick plate portion 3 is reduced. That is, it is preferable that the number of crushed pieces is greater in the thin plate portion 2 than in the thick plate portion 3, since this suppresses the progression of cracks from the thin plate portion 2 to the thick plate portion 3 at the connection portion 4. Specifically, it is preferable that the progression of one or more cracks is suppressed per 30 cm of the length of the connection portion 4, and it is more preferable that the progression of three or more cracks is suppressed.

[0030] The number density of the crushed pieces is determined as follows. First, a head impact test is carried out on each of the thin plate portion 2 and the thick plate portion 3. More specifically, a test specimen is prepared using the thin plate portion 2 or the thick plate portion 3 as a cover glass in the same manner as described in paragraphs

[0081] to

[0088] of Japanese Patent Publication No. 2019-64874, and a rigid model is collided with the test specimen. However, the collision position of the rigid model is the center position of the main surface of the cover glass, and the rigid model is caused to collide with this main surface in a direction perpendicular to the center position. If the cover glass does not break due to the impact of the rigid model, raise the height of the rigid model by 5 cm and collide it again with the cover glass. This is repeated until the cover glass breaks. If the cover glass breaks, measure the number and area of ​​the broken pieces in an area 10 cm or more away from the impact point of the rigid model to calculate the number density of the broken pieces.

[0031] The size and density of the crushed pieces can be adjusted by adjusting the conditions of the chemical strengthening treatment described below. For example, when cooling the glass plate after immersing it in molten salt, cooling is promoted only in the portion that will become the thin plate portion 2 or only in the portion that will become the thick plate portion 3. By using such a method, the size and density of the crushed pieces can be precisely controlled.

[0032] The ratio of the CT of the thin plate portion 2 to the CT of the thick plate portion 3 (thin plate portion / thick plate portion) is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 3.0 or more, in order to maintain the crack strength of the thick plate portion 3. On the other hand, the ratio of the CT of the thin plate portion 2 to the CT of the thick plate portion 3 (thin plate portion / thick plate portion) is preferably 20 or less, more preferably 10 or less, and even more preferably 7 or less, in order to maintain the crack strength of the thin plate portion 2.

[0033] <Connection> The connection part 4 has a first connection surface 4a and a second connection surface 4b. The radius of curvature r1 of the first connecting surface 4a is as described above. That is, the radius of curvature r1 of the first connecting surface 4a is 400 μm or more, preferably 550 μm or more, and more preferably 700 μm or more. On the other hand, the radius of curvature r1 of the first connecting surface 4a is preferably 1300 μm or less, more preferably 1100 μm or less, and even more preferably 900 μm or less. The second connecting surface 4b is defined as a projected surface when the first connecting surface 4a is projected in a direction parallel to the plate thickness direction.

[0034] By adjusting the plate thickness t4 of the connection portion 4, it is possible to increase or decrease the progression of cracks from the thin plate portion 2 to the thick plate portion 3. The thinner the plate thickness t4 of the connection portion 4, the more the progression of cracks across the connection portion 4 can be suppressed, and specifically, the plate thickness t4 of the connection portion 4 is preferably 0.5 mm or less, more preferably 0.3 mm or less, and even more preferably 0.2 mm or less. From the viewpoint of preventing the glass base 1 from easily breaking during transportation or attachment, the thickness t4 of the connecting portion 4 is preferably 0.05 mm or more, more preferably 0.07 mm or more, and even more preferably 0.1 mm or more. The plate thickness t4 of the connection portion 4 is the plate thickness at the thinnest portion of the connection portion 4.

[0035] FIG. 3 is a cross-sectional view showing a modified example of the glass base 1 of the first embodiment. As shown in FIG. 3, the glass base 1 may have an overhang portion 5. The overhang portion 5 is a part of the connection portion 4, and is a portion that protrudes from the thick plate portion 3 toward the thin plate portion 2. The overhang portion 5 has an overhang surface 5a that is a part of the first connection surface 4a of the connection portion 4, and a surface 5b that forms the same plane as the first main surface 3a of the thick plate portion 3. 3 is preferably 150 μm or more, and more preferably 300 μm or more, because when the glass base 1 is viewed from the first main surface 2a and the first main surface 3a side, the boundary between the thin plate portion 2 and the thick plate portion 3 looks sharp, which is preferable in terms of appearance. On the other hand, the curvature radius r2 of the overhang surface 5a is preferably 1100 μm or less, and more preferably 900 μm or less, because it can protect the connection portion 4 and make it less likely to break when the glass base 1 is transported or processed.

[0036] 11 is a cross-sectional view for explaining how to determine the radius of curvature r1 of the first connecting surface 4a and the radius of curvature r2 of the overhanging surface 5a. Hereinafter, a method for determining the radius of curvature r1 and the radius of curvature r2 will be described with reference to FIG.

[0037] The radius of curvature r1 of the first connecting surface 4a of the connecting portion 4 is determined as follows. First, consider a straight line L1 that slopes from the first main surface 3a of the thick plate portion 3 toward the second connecting surface 4b of the connecting portion 4 and intersects with the first main surface 3a of the thick plate portion 3 at an angle θ1 (=45°). When the straight line L1 is moved from the thick plate portion 3 in the direction toward the connecting portion 4 and the straight line L1 first touches the first connecting surface 4a at a single point, the point of contact is designated as a point S1. Next, a point on the first connecting surface 4a that is a length W1 (=10 μm) away from point S1 along the straight line L1 is designated as point S2. Similarly, a point on the first connecting surface 4a that is a length W1 (=10 μm) away from point S1 along the straight line L1 on the opposite side to point S2 is designated as point S3. The radius of a perfect circle that passes through points S1, S2, and S3 is defined as the radius of curvature r1 of the first connecting surface 4a of the connecting portion 4.

[0038] The radius of curvature r2 of the overhanging surface 5a of the overhanging portion 5 is determined as follows. First, consider the line L2 that is perpendicular to the line L1 described above. When the straight line L2 is moved from the thick plate portion 3 in the direction of the overhang portion 5 and the straight line L2 first touches the overhang surface 5a at a single point, the point of contact is designated as a point S4. Next, a point on the overhang surface 5a is defined as point S5, which is a length W2 (=10 μm) away from point S4 along the straight line L2 toward the thick plate portion 3. A point on the opposite side of point S5 along the straight line L2 is a length W2 (=10 μm) away from point S4, which is symmetrical to point S5. Point S6 may or may not be a point on the overhang surface 5a. The radius of a perfect circle that passes through points S4, S5, and S6 is defined as the radius of curvature r2 of overhang surface 5a of overhang portion 5.

[0039] <Method for manufacturing glass substrate> A method for producing the glass base 1 of the first embodiment will be described with reference to FIGS.

[0040] <Preparing the glass plate> FIG. 4 is a cross-sectional view showing a glass plate 41. As shown in FIG. First, as shown in FIG. 4, a glass plate 41 is prepared. Examples of the glass type of the glass plate 41 include soda lime glass and aluminosilicate glass (SiO2-Al2O3-Na2O-based glass). Examples of the glass composition of the glass plate 41 include the glass composition described in paragraph

[0019] of JP 2019-006650 A. When performing a chemical strengthening treatment described later, for example, a chemically strengthened glass based on aluminosilicate glass (for example, "Dragontrail (registered trademark)") is preferably used. The thickness t1 of the glass plate 41 is the same as the thickness t3 of the thick portion 3 of the glass base 1. This is because a part of the glass plate 41 is maintained without being slimmed and becomes the thick portion 3, as will be described later. The glass plate 41 has a first main surface 41a and a second main surface 41b. The sizes of the first main surface 41a and the second main surface 41b are set appropriately.

[0041] Slimming The prepared glass plate 41 is slimmed. The slimming includes masking and etching, which will be described below.

[0042] (masking) FIG. 5 is a cross-sectional view showing a glass plate 41 covered with a mask material 45. As shown in FIG. 5, a part of the first main surface 41a of the glass plate 41 is covered with a mask material 45. More specifically, a surface of the first main surface 41a of the glass plate 41, which surface will become the first main surface 3a of the thick plate portion 3 described above, is covered with the mask material 45. Furthermore, as shown in FIG. 5, the entire second main surface 41b of the glass plate 41 is covered with a mask material 45.

[0043] The material of the mask material 45 is not particularly limited as long as it is a material that has resistance to the etching solution described below, and any conventionally known material can be appropriately selected and used. An example of the mask material 45 is a film-like mask material, and a specific example of such a mask material is an acid-resistant polyethylene terephthalate (PET) material coated with an acrylic adhesive. The mask material 45 may be formed by applying a curable resin to the glass plate 41 using a bar coater or the like and curing the resin. Examples of the curable resin include UV-curable resin and thermosetting resin. Examples of the UV-curable resin include acrylate-based radical polymerization resin and epoxy-based cationic polymerization resin. Examples of the thermosetting resin include epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, polyurethane resin, diallyl phthalate resin, silicone resin, and alkyd resin. From the viewpoint of a fast curing speed, UV-curable resin is preferable.

[0044] A resist pattern may be formed on the first main surface 41a of the glass plate 41 as the mask material 45. In this case, a known resist paint is first coated on the first main surface 41a of the glass plate 41 to obtain a resist film. The obtained resist film is exposed through a photomask having a pattern with a desired shape. The exposed resist film is developed to form a resist pattern.

[0045] (etching) FIG. 6 is a cross-sectional view showing the glass plate 41 after etching. The glass plate 41 covered with the mask material 45 is etched using an etching solution, whereby, as shown in Fig. 6, a part of the portion of the glass plate 41 that is not covered with the mask material 45 is dissolved by the etching solution. The dissolution proceeds gradually from the first main surface 41a toward the second main surface 41b, which is not covered with the mask material 45. In this way, the portion that will become the thin plate portion 2 is formed. Since the etching is performed using an etching solution, a smooth etched surface (curved surface) is formed. In this way, a portion that will become the connection part 4 having the first connection surface 4a with a specific radius of curvature r1 is formed. At this time, if dissolution by etching proceeds excessively, a portion that will become the overhang part 5 (see FIG. 3) is formed. The portion that remains unmelted becomes the thick plate portion 3.

[0046] The etching solution may be an aqueous solution containing an acid, such as hydrogen fluoride (HF), sulfuric acid, nitric acid, hydrochloric acid, or hexafluorosilicic acid, with hydrogen fluoride being preferred. The content of the acid such as hydrogen fluoride in the etching solution is preferably 2 to 10 mass %. When the content is 2% by mass or more, the etching processing time is relatively short, and processing can be easily performed with good productivity. On the other hand, when the content is 10% by mass or less, the variation in the etching rate is suppressed, and uniform processing can be easily performed. Because these effects are superior, the content is more preferably 4 to 8% by mass.

[0047] The temperature of the etching solution is preferably from 10 to 40° C., and more preferably from 20 to 30° C., because this suppresses variation in etching rate and makes it easy to carry out uniform processing.

[0048] The etching method is not particularly limited, but a method in which the glass plate 41 covered with the mask material 45 is immersed in an etching solution is preferable. The immersion time in the etching solution (etching time) is appropriately changed depending on the thickness t1 of the glass plate 41. For example, when the thickness t1 of the glass plate 41 is 0.5 mm or more and 2.5 mm or less, the etching time is preferably 7 minutes or more, more preferably 10 minutes or more, and further preferably 15 minutes or more, while it is preferably 100 minutes or less, and more preferably 60 minutes or less.

[0049] Although so-called wet etching using an etching solution has been described here, dry etching using, for example, fluorine gas can also be used as long as the above-mentioned shape can be obtained.

[0050] After etching, the mask material 45 is appropriately removed by a known method.

[0051] Chemical strengthening treatment The slimmed glass plate 41 may be subjected to a chemical strengthening treatment. When chemical strengthening treatment is performed, glass for chemical strengthening is used as the glass plate 41 . In the chemical strengthening treatment, a conventionally known method can be used, and typically, the glass sheet 41 is immersed in a molten salt. As a result, in the surface layer of the glass sheet 41, alkali ions (Li ions and / or Na ions) are ion-exchanged (substituted) with other alkali ions (Na ions and / or K ions) having a larger ionic radius in the molten salt. This ion exchange forms a layer (compressive stress layer) in which compressive stress is generated due to densification in the surface layer of the glass sheet 41. In this way, the glass sheet 41 can be strengthened.

[0052] The treatment conditions, such as the temperature of the molten salt and the immersion time, may be set so that the compressive stress value (CS) and the thickness (DOL) of the compressive stress layer are desired. For example, the temperature of the molten salt is not particularly limited as long as it is within the strain point of the glass (usually 500 to 600° C.), and is preferably 350° C. or higher, more preferably 400° C. or higher, and even more preferably 430° C. or higher. The immersion time in the molten salt is preferably from 1 to 480 minutes, more preferably from 5 to 240 minutes, and even more preferably from 10 to 120 minutes.

[0053] When the alkali ions contained in the glass sheet 41 are Na ions, the molten salt (inorganic salt composition) preferably contains potassium nitrate (KNO3). The molten salt may further contain at least one salt (fluxing agent) selected from the group consisting of K2CO3, Na2CO3, KHCO3, NaHCO3, K3PO4, Na3PO4, K2SO4, Na2SO4, KOH and NaOH. The content of the flux in the molten salt is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, even more preferably 1 mol% or more, and particularly preferably 2 mol% or more. On the other hand, when K2CO3 is used as the flux, the content is preferably 24 mol% or less, more preferably 12 mol% or less, and even more preferably 8 mol% or less. The molten salt may further contain other chemical species within a range that does not impair the effects of the present invention. Examples of such chemical species include alkali chloride salts such as sodium chloride and potassium chloride; alkali borates such as sodium borate and potassium borate; and the like.

[0054] After being immersed in the molten salt, the glass plate 41 is pulled out of the molten salt and cooled. After the chemical strengthening treatment, the glass plate 41 may be washed with industrial water, ion-exchanged water, or the like.

[0055] Chemical treatment The glass plate 41 that has been subjected to the chemical strengthening treatment may further be subjected to a chemical treatment. The chemical treatment includes an acid treatment and an alkali treatment described below. Between the acid treatment and the alkali treatment, and after the alkali treatment, the glass plate 41 may be washed with industrial water, ion-exchanged water, or the like.

[0056] (Acid treatment) The acid treatment is a treatment in which the chemically strengthened glass plate 41 is immersed in an acid solution. As a result, Na and / or K on the surface of the chemically strengthened glass plate 41 is replaced with H. That is, the surface layer of the compressive stress layer in the chemically strengthened glass plate 41 is altered to become a low-density layer. The acid contained in the acidic solution (for example, an aqueous solution with a pH of less than 7) may be a weak acid or a strong acid. Specific examples of the acid include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, carbonic acid, and citric acid, and these may be used alone or in combination of two or more. The concentration of the acid contained in the acidic solution is preferably 0.1 to 20% by mass. The temperature of the acidic solution is preferably 100° C. or lower. From the viewpoint of productivity, the time for the acid treatment is preferably from 10 seconds to 5 hours, and more preferably from 1 minute to 2 hours.

[0057] (Alkaline treatment) The alkali treatment is a treatment in which the acid-treated glass plate 41 is immersed in a basic solution. This removes part or all of the low-density layer formed by the acid treatment. In this way, cracks and latent scratches present on the surface of the glass plate 41 can be removed together with the low-density layer. The base contained in the basic solution (e.g., an aqueous solution having a pH of more than 7) may be a weak base or a strong base. Specific examples of the base include sodium hydroxide, potassium hydroxide, potassium carbonate, and sodium carbonate, and these may be used alone or in combination of two or more. The concentration of the base contained in the basic solution is preferably 0.1 to 20% by mass from the viewpoint of removability. The temperature of the basic solution is preferably from 0 to 100°C, more preferably from 10 to 80°C, and further preferably from 20 to 60°C. From the viewpoint of productivity, the time for carrying out the alkali treatment is preferably from 10 seconds to 5 hours, and more preferably from 1 minute to 2 hours.

[0058] When the chemical strengthening treatment and the chemical treatment are not performed, the glass plate 41 from which the mask material 45 is removed after slimming becomes the above-mentioned glass base 1. In the case where no chemical solution treatment is performed after the chemical strengthening treatment, the glass plate 41 that has been subjected to the chemical strengthening treatment becomes the glass base 1 described above. When chemical treatment is performed after the chemical strengthening treatment, the glass plate 41 that has been subjected to the chemical treatment becomes the glass base 1 described above.

[0059] [Second aspect] Next, the second embodiment will be described with reference to FIGS. 7 to 10, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. First, the glass base of the second embodiment will be described with reference to FIG.

[0060] <Glass Base> FIG. 7 is a cross-sectional view showing a glass base 11 according to the second embodiment. The plate thickness of the connection portion 4 at its thinnest point is defined as the plate thickness t4 of the connection portion 4. In the glass base 11, the plate thickness t4 of the connection portion 4 is smaller than the plate thickness t2 of the thin plate portion 2. This makes it easier to bend the connection portion 4. Because this effect is superior and because the progression of cracks across the connection portion 4 can be suppressed as described above, the plate thickness t4 of the connection portion 4 is preferably 0.5 mm or less, more preferably 0.3 mm or less, and even more preferably 0.2 mm or less. On the other hand, the lower limit of the plate thickness t4 of the connection portion 4 is not particularly limited, but is preferably 0.05 mm or more, and more preferably 0.1 mm or more. In addition, in the glass base 11 of the second embodiment in a state where it is not elastically deformed, the second main surface 2b of the thin portion 2, the second connecting surface 4b of the connecting portion 4, and the second main surface 3b of the thick portion 3 form the same plane.

[0061] <Method for manufacturing glass substrate> A method for producing the glass base 11 of the second embodiment will be described with reference to FIGS. Since the steps other than slimming (preparation of the glass sheet, chemical strengthening treatment, and chemical treatment) are the same as those in the first embodiment, the explanation will be omitted and only the slimming will be explained.

[0062] Slimming The prepared glass plate 41 is slimmed. The slimming includes polishing, masking and etching, which will be described below.

[0063] (polishing) FIG. 8 is a cross-sectional view showing glass plate 41 after polishing. 8, a portion of the glass plate 41 is polished from the first main surface 41a toward the second main surface 41b so as to reduce the plate thickness t1. The portion that will become the thick plate portion 3 is left unpolished. By polishing, a polished surface 41c is formed in the glass plate 41 at a position lower than the first main surface 41a. In addition, a polished end surface 41d that is perpendicular to the first main surface 41a and the polished surface 41c is formed. The polishing method is not particularly limited, and a conventionally known polishing pad or the like can be appropriately used.

[0064] (masking) FIG. 9 is a cross-sectional view showing a glass plate 41 covered with a mask material 45. As shown in FIG. As shown in FIG. 9, a first main surface 41a, a second main surface 41b and a polished surface 41c of a glass plate 41 are covered with a mask material 45. More specifically, as shown in FIG. 9, only the surface of the polished surface 41c that will become the first main surface 2a of the thin plate portion 2 described above is covered with a mask material 45. The first main surface 41a may be covered with a mask material 45, leaving the surface of the end of the polished end surface 41d exposed. The second main surface 41b is entirely covered with a mask material 45.

[0065] (etching) FIG. 10 is a cross-sectional view showing the glass plate 41 after etching. The glass plate 41 covered with the mask material 45 is etched using an etching solution, whereby, as shown in Fig. 10, a part of the portion of the glass plate 41 that is not covered with the mask material 45 is dissolved by the etching solution. Dissolution gradually progresses from a part of the polished surface 41c, the polished end surface 41d, and a part of the first main surface 41a that are not covered with the mask material 45 toward the inside of the glass plate 41. In this way, a portion that will become the connection portion 4 is formed. Since the etching is performed using an etching solution, a smooth etched surface (curved surface) is formed in the portion that will become the connection portion 4. The portions that remain unmelted become the thin plate portion 2 and the thick plate portion 3. As in the first embodiment, dry etching using, for example, fluorine gas can also be used as long as the above-mentioned shape can be obtained. After etching, the mask material 45 is appropriately removed by a known method.

[0066] When the chemical strengthening treatment and the chemical treatment are not performed, the glass plate 41 from which the mask material 45 is removed after slimming becomes the above-mentioned glass base 11. In the case where no chemical solution treatment is performed after the chemical strengthening treatment, the glass plate 41 that has been subjected to the chemical strengthening treatment becomes the glass base 11 described above. When chemical treatment is performed after the chemical strengthening treatment, the glass plate 41 that has been subjected to the chemical treatment becomes the glass base 11 described above. EXAMPLES

[0067] The present invention will be specifically described below with reference to examples, although the present invention is not limited to the following examples.

[0068] Examples 1 to 7 are working examples, and Examples 8 and 9 are comparative examples.

[0069] Example 1: A glass base 1 of the first embodiment (see Figs. 1 to 6) was produced as described below.

[0070] <Preparing the glass plate> A chemically strengthened glass ("Dragontrail" manufactured by AGC) measuring 1200 mm x 300 mm was prepared as the glass plate 41. The plate thickness t1 of the glass plate 41 was the same as the plate thickness t3 (1.3 mm) of the thick plate portion 3 shown in Table 1 below.

[0071] Slimming Slimming of the first mode was carried out. That is, a prepared glass plate 41 was covered with a mask material 45 and etched with an etching solution. As the mask material 45, a PET film (acid-resistant) coated with an acrylic adhesive was used. The etching solution used was an aqueous solution of 6 mass % hydrogen fluoride (HF). The temperature of the etching solution was 25° C. The etching time was 20 minutes. After etching, the mask material 45 was removed.

[0072] Chemical strengthening treatment The glass plate 41 from which the mask material 45 was removed was subjected to a chemical strengthening treatment. The chemical strengthening treatment was performed by immersing the glass plate 41 in a KNO3 molten salt at 435° C. for 60 minutes. After the chemical strengthening treatment, the glass plate 41 was washed with water. In this manner, the glass base 1 of the first embodiment was obtained.

[0073] Example 2: In the slimming process, the etching time was set to 15 minutes. In the chemical strengthening process, the glass plate 41 was immersed in a KNO3 molten salt at 410° C. for 30 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment.

[0074] Example 3: For slimming, the etching time was set to 25 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment.

[0075] Example 4: The thickness t1 of the glass plate 41 (thickness t3 of the thick portion 3 shown in Table 1 below) was set to 2.0 mm. For slimming, the etching time was 35 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment.

[0076] Example 5: A glass base 11 (see FIGS. 7 to 10) of the second embodiment was produced as described below.

[0077] <Preparing the glass plate> A chemically strengthened glass ("Dragontrail" manufactured by AGC) measuring 1200 mm x 300 mm was prepared as the glass plate 41. The plate thickness t1 of the glass plate 41 was the same as the plate thickness t3 (1.3 mm) of the thick plate portion 3 shown in Table 1 below.

[0078] Slimming Slimming of the second mode was performed. That is, the prepared glass plate 41 was first polished using a polishing pad, then covered with a mask material 45, and then etched. In this case, "Yes" was entered in the "etching time" column of "slimming" in Table 1 below. As the mask material 45, a PET film (acid-resistant) coated with an acrylic adhesive was used. The etching solution used was an aqueous solution of 6 mass % hydrogen fluoride (HF). The temperature of the etching solution was set to 25° C. The etching time was set to the time until the plate thickness t4 of the connection portion 4 became 0.2 mm. After etching, the mask material 45 was removed.

[0079] Chemical strengthening treatment The glass plate 41 from which the mask material 45 was removed was subjected to a chemical strengthening treatment. The chemical strengthening treatment was performed by immersing the glass plate 41 in a KNO3 molten salt at 435° C. for 60 minutes. After the chemical strengthening treatment, the glass plate 41 was washed with water. In this manner, the glass base 11 of the second embodiment was obtained.

[0080] Example 6: In the chemical strengthening treatment, the glass plate 41 was immersed in a KNO3 molten salt at 410° C. for 30 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment.

[0081] Example 7: In the chemical strengthening treatment, a molten salt containing KNO3, 6 mol% K2CO3, and a Na concentration of 2000 mass ppm was used. In this case, the column for "Molten salt composition" in "Chemical strengthening treatment" in Table 1 below states "KNO3 and others." Furthermore, the glass plate 41 that had been subjected to the chemical strengthening treatment was subjected to a chemical solution treatment. Specifically, the glass plate 41 was subjected to an acid treatment by immersing it in an acidic solution (40°C) containing 6% by mass of nitric acid for 2 minutes. Next, the glass plate 41 that had been subjected to the acid treatment was subjected to an alkali treatment by immersing it in a basic solution (40°C) containing 4% by mass of sodium hydroxide for 2 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment.

[0082] Example 8: In slimming, the etching time was set to 5 minutes. Other than that, the same procedure as in Example 1 was carried out to obtain a glass base 1 of the first embodiment. As mentioned above, Example 8 is a comparative example, but for convenience it will be referred to as "glass base 1 of the first embodiment."

[0083] Example 9: In the slimming process, etching was not performed after polishing. In this case, "None" is entered in the "Etching time" column of "Slimming" in Table 1 below. Other than that, the same procedure as in Example 5 was carried out to obtain a glass base 11 of the second embodiment. As described above, Example 9 is a comparative example, but for convenience it will be called "glass base 11 of the second embodiment."

[0084] The physical properties (characteristics) of the obtained glass base 1 and glass base 11 of Examples 1 to 9 were determined. Specifically, the plate thickness t2, the compressive stress value (CS) and depth (DOL) of the compressive stress layer, the internal tensile stress (CT), and the limit bending radius of the thin plate portion 2 were determined. In addition, the plate thickness t3, the compressive stress value (CS) and depth (DOL) of the compressive stress layer, the internal tensile stress (CT), the surface strength, and the number of crushed pieces in the thick plate portion 3 were determined. Also, the ratio of CT of the thin plate portion 2 to CT of the thick plate portion 3 (thin plate portion / thick plate portion) was determined. Also, the radius of curvature r1 of the first connecting surface 4a of the connecting portion 4 was determined. In Example 5, the plate thickness t4 of the connecting portion 4 was determined. Further, the radius of curvature r2 of the overhanging surface 5a of the overhanging portion 5 was obtained. The results are shown in Table 1 below.

[0085] <evaluation> Using the glass bases 1 and 11 of Examples 1 to 9, the ease of bending of the connection parts 4 was evaluated as follows. Fig. 12 is a cross-sectional view for explaining a method for evaluating the ease of bending of the connection portion 4. Note that Fig. 12 illustrates the glass base 1, but the same applies to the glass base 11. First, a position at a distance D1 (=50 mm) from the connecting portion 4 toward the thin plate portion 2 was determined as position P1. More specifically, a position at a distance D1 (=50 mm) from the middle position of the second connecting surface 4b of the connecting portion 4 along the second connecting surface 4b of the connecting portion 4 and the second main surface 2b of the thin plate portion 2 was determined as position P1. Next, while holding the thick portion 3, the thin portion 2 was bent toward the first main surface 2a with the connection portion 4 as a fulcrum. At this time, the distance D2 by which the position P1 was displaced in the thickness direction of the glass base 1 (glass base 11) (direction perpendicular to the direction of the distance D1) was measured. In Table 1 below, if the distance D2 is less than 1.3 mm, it is marked "C", if the distance D2 is 1.3 mm or more and less than 2.5 mm, it is marked "B", and if the distance D2 is 2.5 mm or more, it is marked "A". If the distance D2 is 1.3 mm, the bending radius of curvature corresponds to 1000 mm. If the distance D2 is 2.5 mm, the bending radius of curvature corresponds to 500 mm. It can be evaluated that the longer the distance D2, the easier it is to bend the connection portion 4.

[0086] [Table 1]

[0087] Summary of evaluation results As shown in Table 1 above, in the glass bases 1 of Examples 1 to 4 and Examples 6 to 7, the connecting portions 4 were easier to bend than in the glass base 1 of Example 8. Moreover, in comparison with the glass base 11 of Example 9, the connection portion 4 of the glass base 11 of Example 5 was easier to bend.

[0088] For each of the glass base 1 of Example 1 and the glass base 11 of Example 5, the vicinity of the center of the thin plate portion 2 was broken by a falling ball, and the progression of a crack from the thin plate portion 2 to the thick plate portion 3 was confirmed. Specifically, the number of cracks located 5 mm from the boundary between the first connecting surface 4a and the first main surface 3a toward the connection portion 4 and thin plate portion 2 was compared with the number of cracks located 5 mm from the boundary between the first connecting surface 4a and the first main surface 3a toward the thick plate portion 3. As a result, in Example 1, the number of cracks on the thick plate portion 3 side per 30 cm length of the connection portion 4 was three cracks less than the number of cracks on the thin plate portion 2 side. In Example 5, the number of cracks on the thick plate portion 3 side per 30 cm length of the connection portion 4 was 8 cracks less than the number of cracks on the thin plate portion 2 side. In Examples 1 and 5, since there is a clear difference in the number density of the crushed fragments, it is presumed that the progression of the crack from the thin plate portion 2 to the thick plate portion 3 was suppressed. Furthermore, in Example 5, since the connection portion 4 is thinner than the thin plate portion 2, it is presumed that the crack propagation was further suppressed.

[0089] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2019-128183 filed on July 10, 2019, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0090] 1: Glass substrate 2: Thin plate part 2a: 1st main surface 2b: 2nd principal surface 3: Thick plate section 3a: 1st main surface 3b: 2nd principal surface 4: Connection part 4a: First connection surface 4b: Second connection surface 5: Overhang 5a: Overhang surface 5b: Face 11: Glass substrate 21: Uneven structure 31: Assembly 22: Display panel 23: Display panel 24: Display panel 25: Display panel 26: Panel holder 41: Glass plate 41a: First main surface 41b: Second main surface 41c: Polished surface 41d: Polished end face 45: Masking material r1: Radius of curvature of the first connecting surface r2: Radius of curvature of the overhang surface t1: thickness of glass plate t2: thickness of thin plate t3: Thickness of the thick plate t4: Plate thickness of connection part L1, L2: Straight line W1, W2: Length θ1: Angle S1, S2, S3, S4, S5, S6: points P1:Position D1, D2: distance

Claims

1. a thin plate portion having a first main surface and a second main surface opposite to the first main surface; The plate thickness t of the thin plate portion ２ Plate thickness t is greater than ３ and a thick plate portion having a first main surface and a second main surface opposite to the first main surface; a connecting portion having a first connecting surface connecting a first main surface of the thin plate portion and a first main surface of the thick plate portion, and a second connecting surface connecting a second main surface of the thin plate portion and a second main surface of the thick plate portion, The radius of curvature of the first connecting surface is 400 μm or more, Used as cover glass for in-vehicle display devices, The vehicle-mounted display device has a concave-convex structure, and the glass substrate is assembled to the concave-convex structure in a state where the glass substrate is elastically deformed along the shape of the concave-convex structure.

2. a thin plate portion having a first main surface and a second main surface opposite to the first main surface; The plate thickness t of the thin plate portion ２ Plate thickness t is greater than ３ and a thick plate portion having a first main surface and a second main surface opposite to the first main surface; a connecting portion having a first connecting surface connecting a first main surface of the thin plate portion and a first main surface of the thick plate portion, and a second connecting surface connecting a second main surface of the thin plate portion and a second main surface of the thick plate portion, The plate thickness t which is the plate thickness at the thinnest part of the joint ４ The plate thickness t of the thin plate portion ２ It is smaller than and is used as a cover glass for in-vehicle display devices. The vehicle-mounted display device has a concave-convex structure, and the glass substrate is assembled to the concave-convex structure in a state where the glass substrate is elastically deformed along the shape of the concave-convex structure.

3. The plate thickness t of the connection portion ４ The glass substrate according to claim 2 , wherein the thickness is 0.5 mm or less.

4. A glass base as described in any one of claims 1 to 3, wherein when the glass base is not elastically deformed, the second main surface of the thin plate portion, the second connection surface of the connection portion, and the second main surface of the thick plate portion form the same plane.

5. The plate thickness t of the thin plate portion ２ is 0.05 mm or more and 0.8 mm or less, The plate thickness t of the thick plate portion ３ The glass substrate according to any one of claims 1 to 4, wherein the thickness is 0.5 mm or more and 2.5 mm or less.

6. The glass substrate according to any one of claims 1 to 5, wherein the connection portion has an overhang portion.

7. The glass substrate according to any one of claims 1 to 6, which is a chemically strengthened glass.

8. 8. The glass base according to claim 1, wherein the difference in number density of the broken fragments between the thin portion and the thick portion is 1 fragment / (5 cm×5 cm) or more.

9. A cover glass for covering a display panel, comprising the glass base according to any one of claims 1 to 8.

10. A glass substrate according to any one of claims 1 to 8 assembled to the uneven structure, an assembly in which the thin plate portion of the glass base is assembled to the concave-convex structure in a state in which the thin plate portion is elastically deformed to conform to the shape of the concave-convex structure.

11. A method for manufacturing an assembly, comprising assembling the glass substrate according to any one of claims 1 to 8 into a concave-convex structure, comprising the steps of: a thin plate portion of the glass substrate being elastically deformed to conform to the shape of the concave-convex structure, and assembled to the concave-convex structure;

12. An in-vehicle display device comprising an instrument cluster arranged in front of a driver's seat, a center information display arranged in front of a vehicle between the driver's seat and a passenger seat, and the glass substrate according to any one of claims 1 to 8, The instrument cluster has a concave-convex structure, The thin plate portion of the glass base is assembled to the concave-convex structure in a state where the thin plate portion is elastically deformed along the shape of the concave-convex structure, The thick plate portion of the glass base is attached to the center information display.

13. A method for manufacturing an in-vehicle display device, comprising assembling the glass substrate according to any one of claims 1 to 8 to an instrument cluster disposed in front of a driver's seat and a center information display disposed in front of a vehicle between the driver's seat and a passenger seat, The instrument cluster has a concave-convex structure, The thin plate portion of the glass base is elastically deformed along the shape of the concave-convex structure to be assembled into the concave-convex structure; the thick plate portion of the glass base is assembled to the center information display.

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