JP2023165755A - Disk-shaped glass substrate - Google Patents

Abstract

To enable stable mass production of a thin sheet glass substrate having high surface quality and highly accurate sheet thickness.SOLUTION: A disk-shaped glass substrate is used to cut out one or more thin sheet glass substrates. The disk-shaped glass substrate comprises two circular main surfaces, an outer edge surface, and chamfered surfaces each of which connects each of the circular main surfaces to the outer edge surface and forms a curve when viewed from the side. The disk-shaped glass substrate has a refractive index equal to or higher than 1.60.SELECTED DRAWING: Figure 2

Description

The present invention relates to a disc-shaped glass substrate.

Some head-mounted displays can provide augmented reality by overlaying images onto the landscape. In this type of head-mounted display, a transparent glass light guide is sometimes used in the display section.

For example, Patent Document 1 discloses a light guide including a glass plate. As described in Patent Document 1, since a head-mounted display is mounted on the head, it is required to be lightweight, so it is desirable that the glass plate applied to the light guide be thin. Furthermore, in order to display high-resolution images, it is desirable to use a glass plate with high surface quality, such as the parallelism of the two main surfaces of the glass plate and surface roughness.

International Publication No. 2017/018375

However, it is generally difficult to stably produce thin glass plates (hereinafter referred to as "thin glass substrates") in large quantities with high surface quality.

For example, when manufacturing a thin glass substrate that is large in size and has high surface quality, the size of the glass substrate (hereinafter referred to as a "base glass plate") that is the material thereof also becomes large. In such a large-sized glass blank plate, the frictional force applied to the main surface to be processed during processing such as grinding and polishing tends to become non-uniform. As a result, the surface quality and plate thickness become non-uniform, and it is particularly difficult for large glass blanks to process the glass blank with high surface quality and thinness with high precision.

In addition, for large glass blanks, before and after the processing process, such as when installing the glass blank in each device for grinding, polishing, etc., and when transporting the glass blank between those devices, There is also a high possibility that the glass base plate will be damaged while handling it. Therefore, the yield when manufacturing large-sized thin glass substrates with high surface quality is extremely low.

For example, when manufacturing a thin glass substrate having corners, such as a rectangular thin glass substrate, it is usually manufactured by processing a glass base plate having corners. In this case, the frictional force applied to the surface to be processed during grinding, polishing, etc. tends to become uneven, especially near the corners. Therefore, it is extremely difficult to process a glass base plate having corners to make it thin with high precision and high surface quality.

Even if a thin glass substrate having corners is cut out from a larger thin glass substrate, as described above, the surface quality and thickness tend to be non-uniform in the manufacture of large thin glass substrates. Therefore, there is a high possibility that a thin glass substrate having a corner portion that has been cut out will have variations in surface quality and thickness depending on where on a large thin glass substrate it is cut out. Furthermore, as mentioned above, the yield when producing large thin glass substrates is extremely low. In this way, even if the thin glass substrate to be manufactured is cut out from a larger thin glass substrate, it is extremely difficult to stably produce in large quantities with high surface quality and highly accurate sheet thickness. .

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a disk-shaped glass substrate that enables stable mass production of thin glass substrates having high surface quality and highly accurate plate thickness. With the goal.

In order to achieve the above object, the disc-shaped glass substrate according to the present invention comprises:
A disc-shaped glass substrate for cutting out one or more thin glass substrates,
two circular main surfaces;
an outer peripheral end surface;
a chamfered surface connecting each of the two main surfaces and the outer peripheral end surface and forming a curve when viewed from the side;
The refractive index is 1.60 or more.

According to the present invention, it is possible to stably produce large quantities of thin glass substrates having high surface quality and highly accurate plate thickness.

FIG. 1 is a perspective view of a disc-shaped glass substrate according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a cross section CS1 near the left end of the disc-shaped glass substrate shown in FIG. 1 when viewed from the front. 1 is a flowchart of steps included in a method for manufacturing a disc-shaped glass substrate according to an embodiment of the present invention. FIG. 2 is a perspective view of a disc-shaped glass base plate that is first prepared in a method for manufacturing a disc-shaped glass substrate according to an embodiment. FIG. 5 is an enlarged view showing a cross section CS2 in the vicinity of the left end of the disc-shaped glass base plate shown in FIG. 4 when viewed from the front. FIG. 2 is an enlarged view showing a cross section near the left end of a chamfered disk-shaped blank glass plate when viewed from the front. FIG. 1 is a diagram showing the configuration of a double-sided grinding device according to an embodiment. 1 is a flowchart of steps included in a method for manufacturing a thin glass substrate according to an embodiment of the present invention. It is a figure which shows an example of the location where a disk-shaped glass substrate is cut|disconnected by the cutting process included in the manufacturing method of the thin glass substrate based on one embodiment. 1 is a flowchart of steps included in a method for manufacturing a light guide plate according to an embodiment of the present invention. It is a figure showing an example of the light guide plate produced by the manufacturing method of the light guide plate concerning one embodiment.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. Identical elements are given the same reference numerals throughout the figures. Although the terms top, bottom, front, back, left, and right are used in the description and drawings of the embodiments of the present invention, these terms are used to describe directions and are not intended to limit the present invention. . In the figures, the proportions of the dimensions of each part have been changed as appropriate to make it easier to understand.

(Configuration of disk-shaped glass substrate 100)
As shown in FIG. 1, which is a perspective view, and FIG. 2, which is an enlarged cross-sectional view, a disc-shaped glass substrate 100 according to an embodiment of the present invention is a thin disc-shaped glass board. The refractive index of the disc-shaped glass substrate 100 is preferably 1.60 or more.

In the following, a "thin glass substrate" means a thin glass plate.

The disk-shaped glass substrate 100 is an intermediate body for cutting out one or more thin glass substrates smaller in size. The cut out thin glass substrates are used as a light guide plate, for example, singly or by appropriately combining a plurality of them. When a plurality of cut out thin glass substrates are used in combination as a light guide plate, typically the cut out thin glass substrates are laminated and used as the light guide plate. The light guide is applied to, for example, a display device such as a head-mounted display.

Disc-shaped glass substrate 100 has two main surfaces 101a and 101b, an outer peripheral end surface 102a, and chamfered surfaces 103a and 103b. FIG. 2 is an enlarged view of the cross section CS1 surrounded by the dashed-dotted line in FIG. 1, viewed from the front shown in FIG. Cross section CS1 is a surface extending in the vertical and horizontal directions, and is a cross section along the diameter direction of each of the main surfaces 101a and 101b. Since the cross-section CS1 shown in FIG. 2 is extremely thin, the cross-section CS1 surrounded by the dashed line appears almost like a thick straight line.

The two main surfaces 101a and 101b are generally circular planes arranged in the vertical direction. The diameter of each of the two main surfaces 101a and 101b is, for example, 70 [mm (millimeters)] to 210 [mm].

The length in the vertical direction between the two main surfaces 101a and 101b, that is, the thickness of the disc-shaped glass substrate 100 excluding the outer peripheral end surface 102a and the chamfered surfaces 103a and 103b is, for example, 50 μm (micrometer) to 500 μm. [μm]. The thickness of the disc-shaped glass substrate 100 excluding the outer peripheral end surface 102a and the chamfered surfaces 103a and 103b is preferably 100 [μm] to 400 [μm], more preferably 100 [μm] to 350 [μm]. be.

The parallelism between the two main surfaces 101a and 101b is, for example, less than 1.0 [μm], preferably 0.95 [μm] or less, and more preferably 0.5 [μm] or less. The parallelism between the two main surfaces 101a and 101b may be 0.05 [μm] or more.

Here, the parallelism is a value called TTV (Total Thickness Variation), and is measured in the thickness direction (in this embodiment, the vertical direction) using one of the main surfaces 101a and 101b as a reference plane. This is the difference between the maximum and minimum lengths over the entire surface of the shaped glass substrate 100.

The roughness (root mean square roughness) Rq of the two main surfaces 101a and 101b is, for example, 0.4 [nm] or less.

The outer peripheral end surface 102a is a surface forming a radial end of the disc-shaped glass substrate 100, and is a curved surface that slightly extends in the generally vertical direction. Specifically, the outer peripheral end surface 102a has a generally circular shape when viewed from above or below, and an extremely elongated rectangle that is short in the vertical direction when viewed from the side. Here, the lateral direction is a direction perpendicular to the up-down direction.

The chamfered surfaces 103a, 103b are surfaces that connect each of the two main surfaces 101a, 101b and the outer peripheral end surface 102a at an angle, and are annular when viewed from above or below. That is, the upper chamfered surface 103a is an annular surface that slopes and connects between the outer edge 104a of the upper main surface 101a and the upper end 105a of the outer peripheral end surface 102a. The lower chamfered surface 103b is an annular surface that slopes and connects the outer edge 104b of the lower main surface 101b and the lower end 106a of the outer peripheral end surface 102a.

In this embodiment, the chamfered surfaces 103a and 103b form a straight line when viewed from the side (see FIG. 2). Furthermore, since the chamfered surfaces 103a and 103b are "slanted" as described above, they intersect both of the two main surfaces 101a and 101b and the outer peripheral end surface 102a. The chamfered surfaces 103a and 103b according to this embodiment intersect each of the two main surfaces 101a and 101b and the outer peripheral end surface 102a at obtuse angles (see FIG. 2). Note that the chamfered surfaces 103a and 103b may be curved when viewed from the side.

Up to now, the configuration of the disc-shaped glass substrate 100 according to this embodiment has been described.

The disc-shaped glass substrate 100 according to this embodiment is an intermediate for cutting out one or more thin glass substrates. Further, the disk-shaped glass substrate 100 has a thickness of 100 [μm] to 350 [μm] excluding the outer peripheral end surface 102a and the chamfered surfaces 103a, 103b, and the parallelism of the two main surfaces 101a, 101b is 1. It has high surface quality and highly accurate plate thickness of less than 0 [μm]. Therefore, a thin glass substrate having high surface quality and highly accurate thickness can be cut out.

Further, the disc-shaped glass substrate 100 includes chamfered surfaces 103a and 103b. Therefore, the possibility that the disk-shaped glass substrate 100 will be damaged when cutting out the thin glass substrate is reduced, and the thin glass substrate can be cut out with a higher yield than when the chamfered surfaces 103a and 103b are not provided.

Further, since the disc-shaped glass substrate 100 not only has chamfered surfaces 103a and 103b but also has a disc-shape, it can be used as a relatively large thin glass substrate with high surface quality and highly accurate plate thickness, as will be described in detail later. However, it can be manufactured stably and with a high yield.

Therefore, it becomes possible to stably produce a large quantity of thin glass substrates having a desired shape and having high surface quality and highly accurate thickness.

Further, the refractive index of the disc-shaped glass substrate 100 may be 1.60 or more, and the parallelism between the two main surfaces 101a and 101b may be 0.5 [μm] or less. According to this, for the same reason as mentioned above, it becomes possible to stably produce a large amount of thin glass substrates having a desired shape and having higher surface quality and highly accurate plate thickness.

Further, the thin glass substrate cut out from the disc-shaped glass substrate 100 may be used as a light guide plate, which is used alone or in combination by a method such as lamination. According to this, for the same reason as mentioned above, it becomes possible to stably produce a large quantity of light guide plates having a desired shape and having high surface quality and highly accurate plate thickness.

(Method for manufacturing disk-shaped glass substrate 100)
From here, a method for manufacturing the disk-shaped glass substrate 100, which is an intermediate, will be explained.

The method for manufacturing the disc-shaped glass substrate 100 is a method for manufacturing the disc-shaped glass substrate 100, and includes steps shown in the flowchart of FIG. 3, for example.

A disc-shaped glass base plate 107a is prepared (step S1).

The disc-shaped glass base plate 107a is a disc-shaped glass substrate that is thicker than the disc-shaped glass substrate 100 manufactured as an intermediate. The plate thickness t1 of the disk-shaped glass blank plate 107a is, for example, 0.5 [mm] to 1.0 [mm]. The refractive index of the disk-shaped glass base plate 107a is preferably 1.60 or more. The accuracy of the plate thickness and the quality of each of the main surfaces 101c and 101d may be lower than that of the disc-shaped glass substrate 100.

As shown in FIG. 4, which is a perspective view, and FIG. 5, which is an enlarged cross-sectional view, the disc-shaped glass base plate 107a has two main surfaces 101c and 101d and an outer peripheral end surface 102b.

FIG. 5 is an enlarged view of the cross section CS2 surrounded by the dashed line in FIG. 4, viewed from the front shown in FIG. Cross section CS2 corresponds to cross section CS1 in FIG. 1, and is a surface extending in the vertical and horizontal directions, and is along the diameter direction of each of the main surfaces 101c and 101d. Since the cross-section CS2 shown in FIG. 4 is extremely thin, the cross-section CS2 surrounded by the dashed-dotted line appears almost like a thick straight line, similar to the cross-section CS1 in FIG.

Such a disc-shaped glass base plate 107a is preferably manufactured by an appropriate molding process.

Specifically, for example, the disc-shaped glass base plate 107a may be manufactured by cutting out a cylindrical piece of glass from a block of prismatic glass formed from high refractive glass and then slicing it into a disc shape. Further, for example, the disc-shaped glass base plate 107a may be manufactured by cutting out a large glass plate of a predetermined size formed by a float method or a down-draw method. Furthermore, for example, the disc-shaped glass base plate 107a may be manufactured by press-molding molten glass using a pair of molds.

Here, the outer edges 104c and 104d forming the outer edges of the main surfaces 101c and 101d of the disc-shaped glass base plate 107a do not need to be chamfered. That is, each of the main surfaces 101c and 101d of the disc-shaped glass base plate 107a and the outer peripheral end surface 102b intersect at the outer edge portions 104c and 104d. In other words, each of the outer edges 104c and 104d is a substantially linear boundary between the main surfaces 101c and 101d of the disk-shaped glass base plate 107a and the outer peripheral end surface 102b, and forms a ridgeline. In this embodiment, when viewed from the side, each of the main surfaces 101c and 101d and the outer peripheral end surface 102b intersect at a substantially right angle (see FIG. 5).

Note that, for example, when viewed from the side, the main surfaces 101c and 101d are curved, or the outer peripheral end surface 102b is curved in the vertical direction, so that each of the main surfaces 101c and 101d and the outer peripheral end surface 102b form an acute angle. They may intersect.

Referring again to FIG.
Chamfering is performed on the disk-shaped glass base plate 107a (step S2). In the chamfering process (step S2), the outer edges 104c and 104d of the two main surfaces 101c and 101d of the disc-shaped glass base plate 107a are chamfered.

By performing the chamfering process (step S2), outer edge portions 104c and 104d that serve as boundaries between main surfaces 101c and 101d of disk-shaped glass blank plate 107a and outer peripheral end surface 102b are removed. As shown in FIG. 6, which is an enlarged sectional view, chamfered surfaces 103c and 103d, which are surfaces connecting the main surfaces 101e and 101f of the disk-shaped glass blank 107b and the outer peripheral end surface 102c, are the surfaces of the disk-shaped glass blank. 107b.

Specifically, the upper chamfered surface 103c is an annular surface that slopes and connects the outer edge 104e of the upper main surface 101e and the upper end 105b of the outer peripheral end surface 102c. The lower chamfered surface 103d is an annular surface that slopes and connects the outer edge 104f of the lower main surface 101d and the lower end 106b of the outer peripheral end surface 102c.

In this embodiment, as shown in FIG. 6, chamfered surfaces 103c and 103d that are straight when viewed from the side are formed on a disc-shaped glass blank 107b.

Such a chamfering process (step S2) is performed, for example, by mechanical processing such as grinding using a grindstone. The grinding surface of the grindstone is preferably set at an inclination angle of 30 to 60 degrees, preferably 45 degrees with respect to each of the two main surfaces 101c and 101d. As a result, the angle between the main surfaces 101e and 101f and the chamfered surfaces 103c and 103d when viewed from the side, and the angle between the outer peripheral end surface 102c and each of the chamfered surfaces 103c and 103d when viewed from the side are as follows. It is formed at an obtuse angle of 120 to 150 degrees, preferably 135 degrees.

Here, FIG. 6 shows an enlarged cross section of the disk-shaped glass blank 107b after the chamfering process (step S2) has been performed, that is, the cross section near the left end of the chamfered disk-shaped glass blank 107b when viewed from the front. It is a diagram. Although the position and range of the cross section in the disc-shaped glass base plate 107b are not shown, it is a surface extending in the vertical direction and the horizontal direction, and has a diameter of each of the main surfaces 101e and 101f, as in FIGS. 2 and 5. This is a cross section along the direction.

In FIG. 6, an enlarged cross section of the disk-shaped glass blank plate 107b is shown by a solid line. Further, in FIG. 6, for comparison, an enlarged cross-sectional view (corresponding to the enlarged cross-sectional view shown in FIG. 5) of the disc-shaped glass base plate 107a before chamfering prepared in step S1 is shown with a chain line. Further, in FIG. 6, for comparison, an enlarged cross-sectional view (corresponding to the enlarged cross-sectional view shown in FIG. 2) of the disk-shaped glass substrate 100 manufactured as an intermediate is shown by a dotted line.

As described above, the enlarged views of the disk-shaped glass base plates 107a, 107b and the disk-shaped glass substrate 100 shown in FIG. 6 are generally the same throughout. A cross section of the position and range viewed from the front is shown. That is, FIG. 6 shows that the surfaces of each of the disc-shaped glass base plates 107a and 107b and the disc-shaped glass substrate 100 that cross the vertical center overlap each other, and that the main surfaces 101a to 101f of each of the main surfaces 101a to 101f when viewed from the vertical direction It is a figure which shows the enlarged cross section when the corresponding part of each of disk-shaped glass blank plates 107a and 107b and the disk-shaped glass substrate 100 is arrange|positioned so that a center may correspond, and it is seen from the front.

As can be seen from FIG. 6, the diameters of the main surfaces 101e and 101f of the disc-shaped glass blank 107b and the vertical length of the outer peripheral end surface 102c are determined by the chamfering process (step S2), step S1. It is shorter than the diameter of each of the main surfaces 101c and 101d of the prepared disc-shaped glass base plate 107a and the length of the outer peripheral end surface 102b in the vertical direction.

Further, as shown in FIG. 6, the outer circumferential end surface 102c of the disk-shaped glass base plate 107b, its upper end portion 105b, and its lower end portion 106b are approximately the same as the outer circumferential end surface 102a of the disk-shaped glass substrate 100, which is an intermediate, and its upper end. It coincides with the portion 105a and the lower end portion 106a, respectively. Parts of the upper and lower chamfered surfaces 103c and 103d of the disc-shaped glass base plate 107b are generally in contact with the upper and lower chamfered surfaces 103a and 103b of the disc-shaped glass substrate 100, which is an intermediate body, respectively, as shown in FIG. matches.

Further, with reference to FIG. 6, the thickness of the plate other than the outer peripheral end surface 102c and the chamfered surfaces 103c and 103d of the chamfered disc-shaped glass blank plate 107b is t1 [mm], and the outer peripheral end face of the chamfered disc-shaped glass blank plate 107b is When the plate thickness of 102c is t2 [mm], the following formula (1) is satisfied.
t1×0.15<t2<t1×0.4...Formula (1)

Note that the chamfering step (step S2) is not limited to mechanical processing, and may be performed by chemical processing such as etching. Chamfered surfaces 103c and 103d that are curved when viewed from the side may be formed.

Referring again to FIG.
Grinding is performed on the two main surfaces 101e and 101f of the chamfered disk-shaped glass blank plate 107b (step S3). The grinding process (step S3) is performed mainly for the purpose of adjusting the thickness of the disc-shaped glass blank 107b and adjusting the flatness and parallelism of the two main surfaces 101e and 101f of the disc-shaped glass blank 107b. be exposed.

The machining allowance in the grinding process (step S3) is, for example, about 120 [μm] to 400 [μm]. Here, the machining allowance means the vertical length of the portion removed in the process.

In the grinding process (step S3), for example, two main surfaces 101e and 101f of the chamfered disc-shaped glass blank plate 107b are simultaneously ground using a double-sided grinding device 108 shown in FIG.

FIG. 7 shows the configuration of the double-sided grinding device 108. With reference to this figure, a method of grinding the main surfaces 101e and 101f of the disc-shaped glass blank plate 107b in the grinding process (step S3) will be described.

As shown in FIG. 7, the double-sided grinding device 108 includes a lower surface plate 109, an upper surface plate 110, an internal gear 111, a sun gear 112, and a generally disc-shaped carrier 113 provided with a holding hole.

A diamond sheet (not shown) is adhered to each of the upper surface of the lower surface plate 109 and the lower surface of the upper surface plate 110 in a planar manner. This surface of the diamond sheet becomes the grinding surface. The particle size of the fixed abrasive grains is, for example, about 10 [μm].

The internal gear 111 is a generally hollow annular member with tooth profiles provided on its inner surface. The sun gear 112 is a generally cylindrical member disposed at the center of the internal gear 111, and has teeth on its outer peripheral surface.

The carrier 113 is a holding member that holds the disk-shaped glass base plate 107b through a holding hole. Specifically, the disc-shaped glass base plate 107b is held by the carrier 113 as shown in FIG. 7 by being accommodated so that its outer peripheral end surface 102c is in close contact with the wall surface forming the holding hole of the carrier 113. .

Further, the outer peripheral surface of the carrier 113 is provided with teeth. The carrier 113 holding the disc-shaped glass base plate 107b is arranged such that the teeth of the carrier 113 mesh with the teeth of the internal gear 111 and the sun gear 112, respectively. FIG. 7 shows an example in which four carriers 113 are arranged between the internal gear 111 and the sun gear 112.

Note that the number of carriers 113 arranged in the double-sided grinding device 108 is not limited to four, and may be one, two, three, or five or more. Further, the number of disc-shaped glass blank plates 107b held in one carrier 113 is not limited to one, and may be plural.

The disc-shaped glass base plate 107b held by the carrier 113 is held between the lower surface plate 109 and the upper surface plate 110 with a predetermined pressure. Then, one or both of the upper surface plate 110 and the lower surface plate 109 move. As a result, the disc-shaped glass base plate 107b and each surface plate 109, 110 move relatively, and the two main surfaces 101e, 101f of the disc-shaped glass base plate 107b are polished by the fixed abrasive grains contained in the above-mentioned diamond sheet. ground at the same time.

Note that free abrasive grains may be used instead of fixed abrasive grains. In this case, the disc-shaped glass base plate 107b is ground using a grinding pad replacing the diamond sheet described above and a grinding slurry containing free abrasive grains instead of the fixed abrasive grains in the same manner as in the case using the fixed abrasive grains described above. can do.

Referring again to FIG.
After the grinding process (step S3) has been performed, the disk-shaped glass blank (not shown), that is, the two main surfaces of the ground disk-shaped glass blank are polished (step S4). The polishing process (step S4) is performed for the purpose of removing scratches and distortions during grinding, and creating a mirror surface.

The removal amount in the polishing step (step S4) is, for example, about 10 [μm] to 150 [μm], preferably 20 [μm] to 150 [μm]. It is desirable that the polishing step (step S4) be performed in multiple stages as will be described later, and thereby, for example, the disk-shaped glass substrate 100 described above with reference to FIGS. 1 and 2 may be produced.

In the polishing step (step S4), for example, two main surfaces of the ground disc-shaped glass base plate are simultaneously polished using a double-sided polishing device.

The double-sided polishing device has roughly the same configuration as the double-sided grinding device 108 described above, except that polishing pads are attached to each of the upper surface of the lower surface plate 109 and the lower surface of the upper surface plate 110 instead of diamond sheets. It can be anything. The polishing pad is a flat member having an annular shape as a whole, and is, for example, a resin polisher. Further, in the polishing step (step S4), a polishing slurry containing polishing abrasive grains is used.

Although the double-sided polishing apparatus is not shown for the sake of clarity, in the following description of the polishing process (step S4), the components of the double-sided polishing apparatus used in this process (step S4) will be explained in the double-sided polishing apparatus 108 shown in FIG. Corresponding components are provided with reference numerals.

The carrier 113 holds the ground disc-shaped glass base plate in the same manner as the double-sided grinding device 108 described above. The carrier 113 holding the ground disc-shaped glass base plate is arranged such that the teeth of the carrier 113 mesh with the teeth of the internal gear 111 and the sun gear 112, respectively. The disc-shaped glass base plate held by the carrier 113 is held between a lower surface plate 109 and an upper surface plate 110 provided with a polishing pad under a predetermined pressure. Then, while supplying the polishing slurry, one or both of the upper surface plate 110 and the lower surface plate 109 move. As a result, the ground disc-shaped glass base plate and each surface plate 109, 110 move relatively, and the two main surfaces of the disc-shaped glass base plate are simultaneously polished by the free abrasive grains contained in the polishing slurry. .

The polishing process (step S4) according to the present embodiment includes a first polishing process (step S41) and a second polishing process (step S42), as shown in FIG.

The first polishing step (step S41) is mainly aimed at removing scratches and distortions remaining on the main surface after grinding, or adjusting minute irregularities (microwaviness, roughness, etc.) on the main surface after grinding. It is done as. In the first polishing step (step S41), the two main surfaces of the disc-shaped glass base plate after the grinding step (step S3) are polished using a double-sided polishing device as described above. The removal amount in the first polishing step (step S41) is, for example, about 10 [μm] to 100 [μm].

In the first polishing step (step S41), for example, a polishing slurry containing free abrasives such as cerium oxide abrasive grains and zirconia abrasive grains having a particle size of about 1 [μm] to 2 [μm] is used.

Note that in the first polishing step (step S41), it is preferable to perform polishing in multiple stages by changing at least one of the polishing pad and the polishing slurry. That is, in this case, it is preferable that the combinations of polishing pads and polishing slurries applied to the double-sided polishing apparatus differ from each other at each stage of the first polishing process (step S41). In this way, by performing the first polishing step (step S41) in multiple stages, it is possible to particularly adjust the parallelism of the disc-shaped glass base plate within the range of 0.05 [μm] to 0.95 [μm]. As a result, it becomes possible to obtain a disc-shaped glass substrate 100 having high surface quality and highly accurate plate thickness.

The second polishing step (step S42) is performed mainly for the purpose of mirror-finishing the main surface and reducing roughness. In the second polishing step (step S42), the two main surfaces of the disc-shaped glass base plate after the first polishing step (step S41) are polished using a double-sided polishing device as described above. . The machining allowance in the second polishing step (step S42) is, for example, about 1 [μm].

In the second polishing step (step S42), the type and particle size of free abrasive grains contained in the polishing slurry and the hardness of the resin polisher are different from those in the first polishing step (step S41). In the second polishing step (step S42) according to the present embodiment, the free abrasive grains are, for example, colloidal silica mixed in the slurry with a particle size of about 10 [nm (nanometer)] to 50 [nm]. Fine particles are used.

Note that the second polishing step (step S42) only needs to be different from the first polishing step (step S41) in at least one of the type and particle size of free abrasive grains contained in the polishing slurry, and the polishing pad. That is, the combination of the hardness of the resin polisher applied to the double-sided polisher and the polishing slurry may be different between the first polishing step (step S41) and the second polishing step (step S42).

By performing the second polishing step (step S42), the roughness (root mean square roughness) Rq of the main surface can be set to 0.4 [nm] or less. As a result, it becomes possible to produce a disc-shaped glass substrate 100 with high surface quality, and by cutting it out from the disc-shaped glass substrate 100, it becomes possible to produce a thin glass substrate with high surface quality.

By performing a grinding process (step S3) and a polishing process (step S4) on each of the two main surfaces 101e and 101f of the disc-shaped glass base plate 107b, a highly accurate plate thickness as shown in FIG. A disc-shaped glass substrate 100 can be manufactured. The plate thickness t3 of the disc-shaped glass substrate 100 to be produced is, for example, 50 [μm] to 500 [μm], preferably 100 [μm] to 400 [μm] in a portion excluding the outer peripheral end surface 102a and the chamfered surfaces 103a and 103b. [μm], more preferably 100 [μm] to 350 [μm].

Further, the disc-shaped glass substrate 100 to be manufactured may be large-sized with a diameter of 70 to 210 [mm]. The disk-shaped glass substrate 100 to be manufactured has a high surface quality in which the parallelism of the two main surfaces 101a and 101b is less than 1.0 [μm], preferably 0.95 [μm] or less. , more preferably 0.5 [μm] or less. The parallelism between the two main surfaces 101a and 101b of the disc-shaped glass substrate 100 may be 0.05 [μm] or more.

In the grinding step (Step S3) and the polishing step (Step S4), at least a portion of each of the chamfered surfaces 103c and 103d formed in the chamfering step (Step S2) remains after performing the steps S3 to S4. The main surface of the disc-shaped glass blank is ground and polished with a machining allowance within the range. Thereby, the chamfered surfaces 103a and 103b can be reliably provided on the disc-shaped glass substrate 100 produced by polishing (step S4).

Further, the outer circumferential end surface 102a and chamfered surfaces 103a, 103b of the disk-shaped glass substrate 100 are prepared by polishing the outer circumferential end surface 102c of the chamfered disk-shaped glass base plate 107b to t2 [mm] (step S4). When the plate thickness other than that is t3 [mm] (see FIG. 6), the following formula (2) is satisfied.
t3×0.5<t2...Formula (2)

Referring again to FIG.
After the polishing process (step S4), the disc-shaped glass substrate 100 is cleaned using a neutral detergent, pure water, IPA (isopropyl alcohol), or the like. As a result, the disc-shaped glass substrate 100 shown in FIG. 1 is completed. Note that the shape and size of the disc-shaped glass substrate 100, such as the thickness of the disc-shaped glass substrate 100, are generally almost unchanged before and after the cleaning treatment (step S5).

The method for manufacturing disk-shaped glass substrate 100 according to this embodiment includes a chamfering step (step S2). Damage to the disc-shaped glass blank due to cracking can be suppressed during the subsequent processing steps (steps S3 to S5) and before and after each of the processing steps (steps S3 to S5).

Furthermore, the grinding process (step S3) and the polishing process (step S4) are performed after the chamfering process (step S2), and since the object to be ground and polished is disk-shaped, no corners are included. As a result, the frictional force applied to each of the main surfaces 101e and 101f of the disc-shaped glass base plate 107b in steps S3 to S4 tends to be uniform. As a result, the disc-shaped glass base plate 107b can be thinned with high precision and high surface quality.

Furthermore, the disk-shaped glass substrate 100 having high surface quality and highly accurate plate thickness as described above with reference to FIGS. 1 and 2 can be manufactured. That is, since the disc-shaped glass substrate 100 has a uniform thickness and a uniform high surface quality, it is possible to cut out a thin glass substrate of a desired shape or size that has a high surface quality and a highly accurate thickness.

Furthermore, by including a chamfering step (step S2), chamfered surfaces 103a and 103b are also formed on the manufactured disk-shaped glass substrate 100. This reduces the possibility that the disk-shaped glass substrate 100 will be damaged when cutting out the thin glass substrate from the disk-shaped glass substrate 100, and it is possible to cut out the thin glass substrate at a higher yield than when there are no chamfered surfaces 103a and 103b. can.

Therefore, it becomes possible to stably produce a large quantity of thin glass substrates having a desired shape and having high surface quality and highly accurate thickness.

Furthermore, as described above, the grinding process (step S3) and the polishing process (step S4) are performed after the chamfering process (step S2), and since the object to be ground and polished is disk-shaped, it does not include corners. . Therefore, a large disk-shaped glass substrate 100 with a diameter of 70 to 210 mm, high surface quality, and highly accurate plate thickness can be manufactured stably and at a high yield. Usually, more thin glass substrates can be cut out from the large disk-shaped glass substrate 100 than from the small disk-shaped glass substrate 100. Therefore, by cutting out thin glass substrates from the large disc-shaped glass substrate 100, it becomes easier to stably mass-produce thin glass substrates having high surface quality and highly accurate thickness.

(Method for manufacturing thin glass substrate 114)
From here, a method for manufacturing the thin glass substrate 114 will be explained.

The method for manufacturing thin glass substrates 114 according to the present embodiment is a method for manufacturing a plurality of thin glass substrates 114 from disk-shaped glass substrate 100 as an intermediate, and includes, for example, the steps shown in the flowchart of FIG. include.

In the method for manufacturing a thin glass substrate 114 according to the present embodiment, as shown in FIG. 8, after steps S1 to S5 described above with reference to FIG. Glass substrate 114 is cut out (step S6). In other words, the cutting process (step S6) is performed on the disc-shaped glass substrate 100 manufactured by the method for manufacturing disc-shaped glass substrate 100.

Here, in FIG. 8, for the sake of clarity, steps similar to steps S1 to S5 in the method for manufacturing the disc-shaped glass substrate 100 are omitted.

Specifically, in the cutting process (step S6), as shown in FIG. 9, the disc-shaped glass substrate 100 is cut along the straight dotted line in the figure. As a result, a plurality of rectangular thin glass substrates 114 as shown enlarged in FIG. 9 are cut out from the disc-shaped glass substrate 100.

According to the method for manufacturing the thin glass substrate 114, as described above, the disk-shaped glass substrate 100 having a uniform thickness and uniform high surface quality can be manufactured through the steps S1 to S5. With such a disc-shaped glass substrate 100, a plurality of thin glass substrates 114 having high surface quality and highly accurate plate thickness can be obtained regardless of where they are cut out. Moreover, even if the thin glass substrate 114 has a corner such as a rectangle, it is possible to obtain a thin glass substrate 114 having high surface quality and highly accurate thickness.

Furthermore, by including the chamfering step (step S2), as described above, the possibility that the disc-shaped glass substrate 100 will be damaged when cutting out the thin glass substrate 114 from the disc-shaped glass substrate 100 is reduced. Therefore, even if the thin glass substrate 114 has corners such as a rectangle as exemplified here, it can be obtained at a higher yield than when the chamfered surfaces 103a and 103b are not present.

Therefore, it is possible to stably produce a large amount of thin glass substrates 114 having corners with high surface quality and highly accurate thickness.

Although an example has been described in which a plurality of rectangular thin glass substrates 114 are cut out in the cutting process (step S6), only one thin glass substrate 114 may be cut out from the disc-shaped glass substrate 100. Further, in the cutting process (step S6), the shape and size of each of the one or more thin glass substrates 114 cut out from the disc-shaped glass substrate 100 may be changed as appropriate, for example, a shape without corners. It may be. According to this, it becomes possible to stably produce a large quantity of thin glass substrates 114 having a desired shape and having high surface quality and highly accurate thickness.

Note that the thin glass substrate 114 manufactured by the method for manufacturing the thin glass substrate 114 described here may be used alone as a light guide plate. In this case, the method for manufacturing the thin glass substrate 114 described here may be adopted as the method for manufacturing the light guide plate. According to this, it becomes possible to stably produce a large quantity of light guide plates having a desired shape and having high surface quality and highly accurate plate thickness.

(Method for manufacturing light guide plate)
From here, a method for manufacturing the light guide plate 115 will be explained.

The method for manufacturing the light guide plate 115 according to this embodiment is a method for manufacturing the light guide plate 115 by combining a plurality of thin glass substrates 114, and includes steps shown in the flowchart of FIG. 10, for example.

In the method for manufacturing the light guide plate 115 according to the present embodiment, as shown in FIG. 10, after the cutting process (step S6) described above with reference to FIG. 8, the cut thin glass substrate 114 is laminated. (Step S7). In other words, the lamination process (step S7) is performed on the thin glass substrate 114 manufactured by the method for manufacturing the thin glass substrate 114.

Here, in FIG. 10, for the sake of clarity, steps similar to steps S1 to S6 in the method for manufacturing the thin glass substrate 114 are omitted. That is, steps S1 to S5 in the method for manufacturing the light guide plate 115 may be the same as steps S1 to S5 in the method for manufacturing the disc-shaped glass substrate 100, respectively.

Specifically, in the lamination step (step S7), the thin glass substrates 114 are stacked vertically with adjacent thin glass substrates 114 fixed to each other, thereby producing a light guide plate 115 as shown in FIG. 11.

Although FIG. 11 shows an example in which four thin glass substrates 114 are stacked, the number of thin glass substrates 114 stacked in the stacking step (step S7) may be determined as appropriate.

According to the method for manufacturing the light guide plate 115, the light guide plate 115 can be manufactured by cutting out a plurality of thin glass substrates 114 having high surface quality and highly accurate plate thickness, and laminating them. As described above, it is possible to stably produce a large amount of thin glass substrates 114 having corner portions with high surface quality and highly accurate plate thickness. Therefore, it is possible to stably produce a large quantity of light guide plates 115 having corners with high surface quality and highly accurate plate thickness.

Note that the thin glass substrate 114 cut out from the disk-shaped glass substrate 100 in the cutting process (step S6) may have a desired shape and size, as described above. According to this, it becomes possible to stably produce a large quantity of light guide plates 115 having a desired shape and having high surface quality and highly accurate plate thickness.

Although an embodiment and a modified example of the present invention have been described above, the present invention is not limited to these. For example, the present invention includes forms in which the embodiments and modifications described above are appropriately combined, and forms in which changes are made as appropriate to the forms.

The present invention can be used for mass production of thin glass substrates with high surface quality, such as glass substrates applied to display devices such as head-mounted displays.

100 Disc-shaped glass substrate 101a-101f Main surface 102a-102c Outer peripheral end surface 103a-103d Chamfered surface CS1, CS2 Cross section 104a-104f Outer edge 105a-105b Upper end 106a-106b Lower end 107a-107b Disc-shaped glass base plate 1 08 Double-sided grinding Device 109 Lower surface plate 110 Upper surface plate 111 Internal gear 112 Sun gear 113 Carrier 114 Thin glass substrate 115 Light guide plate

Claims (8)

A disc-shaped glass substrate for cutting out one or more thin glass substrates,
two circular main surfaces;
an outer peripheral end surface;
a chamfered surface connecting each of the two main surfaces and the outer peripheral end surface and forming a curve when viewed from the side;
A disc-shaped glass substrate having a refractive index of 1.60 or more. The disc-shaped glass substrate according to claim 1, wherein the distance between the two main surfaces is 50 to 500 μm. The disc-shaped glass substrate according to claim 1 or 2, wherein the distance between the two main surfaces is 350 μm or less. The disk-shaped glass substrate according to any one of claims 1 to 3, characterized in that the degree of parallelism is 0.5 μm or less. The disc-shaped glass substrate according to any one of claims 1 to 4, wherein the root mean square roughness Rq of the two main surfaces is 0.4 nm or less. When the thickness of the outer circumferential end face is t2 mm, and the thickness of the plate other than the outer circumferential end face and the chamfered surface is t3 mm, the disc-shaped glass substrate for cutting out one or more thin glass substrates is t3×0.5. The disc-shaped glass substrate according to any one of claims 1 to 5, wherein <t2 is satisfied. The disk-shaped glass substrate according to any one of claims 1 to 6, wherein the thin glass substrate is used alone or in combination as a light guide plate. The disk-shaped glass substrate according to claim 7, wherein the thin glass substrates are used as a light guide plate by laminating them.

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