Patent Application
20240101473
The present invention relates to a method for manufacturing a glass plate, the method including processing for irradiating an inner circumferential edge surface of an annular glass plate with a laser beam, a method for manufacturing a glass substrate for a magnetic disk (magnetic-disk glass substrate) using this method for manufacturing a glass plate, a method for manufacturing a magnetic disk, and an apparatus for processing a glass plate.
A magnetic disk obtained by providing a magnetic layer on an annular nonmagnetic glass substrate for a magnetic disk is used in a hard disk drive (HDD) device for recording data.
When a magnetic-disk glass substrate is manufactured, particles are likely to form on edge surfaces of an annular glass plate that is the base of the magnetic-disk glass substrate that will be a final product, and therefore it is preferable that edge surfaces of the annular glass plate are smoothened in order to inhibit minute particles from adhering to main surfaces thereof, and from adversely affecting the performance of the magnetic disk. Also, it is preferable that edge surfaces of the glass plate have target shapes to precisely incorporate a magnetic disk into an HDD device, and make an outer circumferential edge surface of the glass substrate suitable to be held by a jig for holding the outer circumferential edge surface when a magnetic film is formed on the main surfaces of the glass substrate.
A method for chamfering an edge of a glass plate using a laser beam is known as a method for making an edge surface of an annular glass plate into a target shape. A technique is known by which it is possible to easily smoothen inner and outer circumferential edge surfaces of a glass substrate for an information recording medium, with use of a laser beam, at low costs, for example (JP 2002-150546A).
Specifically, when an inner circumferential edge surface is chamfered, a reflective mirror is arranged in an inner hole in an annular glass plate, a laser beam is emitted from above a main surface of the glass plate toward the reflective mirror, and the inner circumferential edge surface is irradiated with reflected light of a laser beam reflected by the reflective mirror.
However, if inner circumferential edge surfaces of a plurality of glass plates are irradiated with a laser beam using the above-described technique, in order to avoid collision between a glass plate and the reflective mirror, every time a glass plate is replaced, the reflective mirror needs to be retrieved from the inner hole and the reflective mirror needs to be moved into the inner hole in a glass plate that is to be processed next. In this case, a moving mechanism for moving the reflective mirror is required, and it also takes time to move the reflective mirror. On the other hand, if the glass plate is moved without moving the reflective mirror, the path on which the glass plate is to be moved also becomes complicated. Thus, the configuration of a photoirradiation device with use of a reflective mirror becomes complicated, and productivity deteriorates.
In view of this, the present invention aims to provide a method for manufacturing a glass plate by which an annular glass plate can be irradiated with a laser beam with a simple device configuration when manufacturing the glass plate by irradiating an inner circumferential edge surface of the glass plate with a laser beam, a method for manufacturing a magnetic-disk glass substrate, and a method for manufacturing a magnetic disk.
One aspect of the present invention is a method for manufacturing a glass plate, the method including processing for irradiating an inner circumferential edge surface extending along an inner hole in an annular glass plate with a laser beam along the inner circumferential edge surface.
In the processing, when the inner circumferential edge surface is irradiated with the laser beam, the laser beam is concentrated by a condenser lens and formed into diffused light, and the inner circumferential edge surface is irradiated with the diffused light from a direction inclined with respect to a main surface of the glass plate.
It is preferable that corner portions present between the inner circumferential edge surface and the main surfaces on both sides of the glass plate are chamfered through the processing.
It is preferable that an inclination angle of a central axis of the laser beam with respect to the main surface is 20 degrees or less.
It is preferable that a diffusion angle of the laser beam is 20 degrees or less.
It is preferable that the corner portions present between the inner circumferential edge surface and the main surfaces on both sides of the glass plate are chamfered through the processing, and
a cross-sectional shape of the inner circumferential edge surface in which the corner portions are chamfered is line-symmetric with respect to a center line that passes through the center of the glass plate in a thickness direction of the glass plate and that is parallel to the main surfaces.
It is preferable that a position where the laser beam is concentrated by the condenser lens is located above a plane that includes the main surface outward in a radial direction of a position on the inner circumferential edge surface that faces an irradiation position on the inner circumferential edge surface that is irradiated with the laser beam across the center of the inner hole.
It is preferable that the glass plate is a glass substrate that is a base of a glass substrate for a magnetic disk.
It is preferable to grind or polish the main surface of the glass plate without polishing the inner circumferential edge surface, after irradiation with the laser beam.
Another aspect of the present invention is a method for manufacturing a magnetic-disk glass substrate. With this method for manufacturing a magnetic-disk glass substrate, after the glass plate is manufactured using the method for manufacturing a glass plate, the magnetic-disk glass substrate is manufactured by grinding or polishing the main surface of the glass plate.
Yet another aspect of the present invention is a method for manufacturing a magnetic disk, in which a magnetic film is formed on the main surface of the glass plate manufactured using the method for manufacturing a magnetic-disk glass substrate.
Yet another aspect of the present invention is an apparatus for processing a glass plate configured to perform processing for irradiating an inner circumferential edge surface extending along an inner hole in an annular glass plate with a laser beam along the inner circumferential edge surface.
In the processing, when the inner circumferential edge surface is irradiated with the laser beam, the laser beam is concentrated by a condenser lens and formed into diffused light, and the inner circumferential edge surface is irradiated with the diffused light from a direction inclined with respect to a main surface of the glass plate.
It is preferable that corner portions present between the inner circumferential edge surface and the main surfaces on both sides of the glass plate are chamfered through the processing.
According to the above-described method for manufacturing a glass plate, method for manufacturing a magnetic-disk glass substrate, method for manufacturing a magnetic disk, and apparatus for processing a glass plate, it is possible to perform irradiation with a laser beam, using a device that has a simple configuration and that manufactures a glass plate by irradiating an inner circumferential edge surface of an annular glass plate with a laser beam.
The following describes a method for manufacturing a glass plate, an apparatus for processing a glass plate, a method for manufacturing a magnetic-disk glass substrate, and a method for manufacturing a magnetic disk according to one embodiment in detail.
An edge surface of an annular glass plate is chamfered, and the glass plate manufactured using a method for manufacturing a glass plate according to one embodiment is to be used in a magnetic-disk glass substrate, for example.
A glass plate 1 shown in
The glass plate 1 shown in
In the case of a magnetic-disk glass substrate, a magnetic disk is produced by grinding and/or polishing the main surfaces of the glass plate 1 as needed, and then forming a magnetic film on the main surfaces of the glass plate 1.
As shown in
The luminous flux of the diffused light L2 is small in the vicinity of the light concentration position 12. If the luminous flux is large, a portion of the annular glass blank 2 that faces an irradiation position 14 of the inner circumferential edge surface 7 that is irradiated with the laser beam L across the center of the glass blank 2 obstructs an optical path and light is scattered, or even if light passes through the opposing portion, the intensity of transmitted light decreases, making it difficult to form the chamfered surface 5, or it is not possible to secure enough light intensity to make the cross-sectional shape of the inner circumferential edge surface line-symmetric.
In this embodiment, the amount of luminous flux can be reduced near a position (a later-described position A) where the glass blank 2 is likely to obstruct an optical path, by using the diffused light L2 of the light that has passed through the light concentration position 12. As a result, the laser beam L is likely to avoid the position where the glass blank 2 is likely to obstruct the optical path. Thus, it is possible to reduce the inclination angle of the diffused light L2 with respect to the main surfaces of the glass blank 2.
Also, by irradiating the inner circumferential edge surface 7 with the diffused light L2 at a small inclination angle with respect to the main surfaces of the glass blank 2, at the time of irradiation, the temperatures of corner portions on both sides in the thickness direction of the inner circumferential edge surface 7 at the light concentration position 12 approach substantially the same temperature. Thus, the cross-sectional shape of the inner circumferential edge surface can be easily made into a line-symmetric target shape. That is, the cross-sectional shape of the inner circumferential edge surface can be made line-symmetric with respect to the center line that passes through the center of the glass plate 1 in the thickness direction of the glass plate 1 and that is parallel to the main surfaces.
Here, a “line-symmetric shape” refers to a shape in which the maximum deviation of the deviations of the contours of edge surfaces in a direction that is parallel to the main surfaces at positions in the thickness direction obtained when the contour of a cross-sectional shape thereof is folded back with respect to the center line that passes through the center of the glass plate 1 in the thickness direction of the glass plate 1 and that is parallel to the main surfaces is 30 [μm] or less. The maximum deviation is more preferably 20 [μm] or less. If this maximum deviation exceeds 30 [μm], when the inner hole 3 is held in a film forming device for forming a magnetic film or the like for making the glass plate 1 function as a magnetic disk, the posture of the glass plate 1 is unstable, and problems such as cracking or dropping of the glass plate 1 are likely to occur. Also, a “line-symmetric shape regarding the cross-sectional shape of the inner circumferential edge surface of the glass blank 2” refers to a shape in which the maximum deviation obtained when using the glass blank 2 instead of the glass plate 1 is 30 [μm] or less.
Note that, in order to prevent an opposing portion 20 located at a position that corresponds to the irradiation position 14 of the inner circumferential edge surface 7 across the center of the inner hole 3 from obstructing the optical path, the light concentration position 12 is preferably set to an area above the position of the inner circumferential edge surface 7 (hereinafter, also referred to as the “position A”) facing the irradiation position 14 irradiated with the diffused light L2 on the inner circumferential edge surface 7 across the center of the inner hole 3. The light concentration position 12 may be adjusted in various ways in consideration of the specifications of the laser beam L (the inclination angle θ, the diffusion angle ø, and the like), the plate thickness of the glass blank 2, the diameter of the inner hole 3, and the like. Also, the light concentration position 12 is preferably set to be located above a plane including the main surfaces located outward in a radial direction of the position A. Accordingly, it is also possible to obtain the effect of sufficiently widening the area (spot diameter) of the luminous flux of the diffused light L2 at the irradiation position 14. In other words, the light concentration position 12 is preferably spaced apart from the position A outward in the radial direction by a distance of more than 0 mm in a plan view. This distance is more preferably 10 mm or more, and even more preferably 20 mm or more. Although there is no particular limitation on the upper limit of the distance, in order to avoid an increase in the size of an apparatus, it is sufficient that the distance is 300 mm or less, for example. Note that a “plan view” used in this specification refers to a view from a direction perpendicular to the main surfaces of the glass plate.
The laser beam L can be emitted from a laser oscillator (not shown). Also, in order to move the laser beam L (diffused light L2) relative to the inner circumferential edge surface 7 in the circumferential direction of the glass blank 2, it is possible to use a method in which the center of the annular shape of the glass blank 2 is positioned at and fixed to the rotation center of a turntable (not shown), and the glass blank 2 is rotated, for example. It is sufficient that the inner circumferential edge surface 7 of the glass blank 2, which rotates together with the turntable, is scanned along the inner circumferential edge surface 7 with the laser beam L by irradiating the inner circumferential edge surface 7 of the glass blank 2 with the laser beam L. It is sufficient that the relative moving speed between the laser beam L and the inner circumferential edge surface 7 of the glass blank 2 is set to 0.7 to 100 [mm/s], for example.
It is possible to use a CO2 laser beam as the laser beam L, for example. The wavelength of the CO2 laser beam is preferably 3 μm or more. Note that the laser beam L may be a laser beam other than a CO2 laser beam as long as it has an oscillation wavelength at which glass absorbs the laser beam, and examples thereof include CO laser beams (having an oscillation wavelength of about 5 μm or about 10.6 μm) and Er-YAG laser beams (having an oscillation wavelength of about 2.94 μm).
The size and shape of the luminous flux (irradiation spot) of the laser beam L at an irradiation position on the inner circumferential edge surface 7 need only be a circular shape with a diameter of 1 to 10 mm, or may be an elliptical shape having an area equivalent to that of the circular shape. Although the size and shape of the irradiation spot may be selected as appropriate according to the plate thickness of the glass blank 2 to be chamfered, the size of the irradiation spot is preferably larger than the plate thickness of the glass blank 2 at least in the plate thickness direction, from the viewpoint of making the cross-sectional shape of the inner circumferential edge surface 7 line-symmetric.
It is sufficient that an average power density of the luminous flux at the position where the inner circumferential edge surface 7 is irradiated with the laser beam L is 1 to 30 [W/mm2], for example. The average power density is a value obtained by dividing the total power [W] of the laser beam L by the area [mm2] of the luminous flux on a plane including a portion of the inner circumferential edge surface 7 irradiated with the laser beam L (i.e., if part of the luminous flux protrudes from the inner circumferential edge surface 7, the area of the protruding portion is also included). It is sufficient that the total power of the laser beam L is 10 to 300 [W], for example.
When the inner circumferential edge surface 7 is irradiated with the diffused light L2, the inner circumferential edge surface 7 is preferably irradiated with the laser beam L such that the central axis of the luminous flux of the diffused light L2 passes above the center of the annular shape of the glass blank 2 (a position above the glass blank 2 on the central axis of the glass blank 2 that is orthogonal to the main surfaces). Accordingly, the angle at which the laser beam L is incident on the inner circumferential edge surface 7 approaches vertical. Therefore, energy loss caused by reflection of the laser beam L can be minimized, and thus the chamfered surface 5 can be efficiently formed.
Further, it is preferable to heat the glass blank 2 before and/or during irradiation with the laser beam L. This makes it possible to reduce residual strain that occurs in the vicinity of the inner circumferential edge surface after chamfering performed using the laser beam L. As a heating method, it is sufficient that the temperature of the entire glass blank 2 is increased by disposing a heater or the like in the vicinity of the glass blank 2, for example. An infrared heater such as a halogen lamp heater, a carbon heater, or a sheathed heater can be used as the heater, for example.
By irradiating the inner circumferential edge surface 7 with the diffused light L2 of the laser beam L that has passed through the light concentration position 12 in this manner, a reflective mirror need not be disposed in the inner hole 3 as is conventional, and thus the path on which the glass blank 2 and the glass plate 1 are transported is not restricted, and it is possible to simplify a device configuration.
As described above, an inclination angle θ (see
Also, from the viewpoint of easily reducing the inclination angle θ, a diffusion angle ø of the laser beam L (see
Although there is no particular limitation on a method for manufacturing the glass blank 2 to be irradiated with the laser beam L, the glass blank 2 is manufactured using a float method, a downdraw method, or a pressing method, for example. It is possible to obtain a plurality of disk-shaped glass plates each provided with an inner hole from wide glass sheets manufactured using a float method or a downdraw method. In a method for obtaining disk-shaped glass plates from wide glass sheets, disk-shaped glass plates may be obtained through cutting with use of a well-known scriber, or by irradiating the glass plates with a laser beam to form a circular defect, and cut out into an annular shape.
An apparatus for processing a glass plate according to an embodiment is configured to carry out the above-described method for manufacturing a glass plate. The apparatus for processing a glass plate includes a photoirradiation device. The photoirradiation device includes a laser oscillator and optical system components. The optical system components include lenses such as the condenser lens 10, and the like. Also, the apparatus for processing a glass plate may include a holding portion that holds a glass blank by fixing or placing the glass blank, for example, and a rotation mechanism for rotating the holding portion. Furthermore, the apparatus for processing a glass plate may be provided with a turntable in which functions of the holding portion and the rotation mechanism are integrated with each other.
If a magnetic-disk glass substrate is manufactured from the glass plate 1 provided with the above-described chamfered surfaces 5, various processes that will be described below are performed such that the glass plate 1 has properties suitable for a magnetic-disk glass substrate, which will be a final product.
The main surfaces of the glass plate 1 are ground and polished.
In grinding and polishing processing, the glass plate 1 is ground and/or polished. When grinding and polishing are both to be performed, polishing is performed after grinding.
In grinding processing, a double-side grinding apparatus provided with a planetary gear mechanism is used to grind a pair of main surfaces of the glass plate 1. Specifically, the main surfaces on both sides of the glass plate 1 are ground while the outer circumferential edge surface of the glass plate 1 is held in a holding hole provided in a holding member (grinding carrier) of the double-side grinding apparatus. The double-side grinding apparatus has a pair of upper and lower surface plates (an upper surface plate and a lower surface plate), and the glass plate 1 is held between the upper surface plate and the lower surface plate. Then, it is possible to grind the two main surfaces of the glass plate 1 by moving the glass plate 1 and the surface plates relative to each other while moving one or both of the upper surface plate and the lower surface plate and supplying coolant. Grinding members obtained by forming fixed abrasive particles in which diamond microparticles are fixed by resin into a sheet shape are mounted on the surface plates, and then grinding processing can be performed, for example.
Then, first polishing is performed on a pair of main surfaces of the ground glass plate 1. Specifically, the main surfaces on both sides of the glass plate 1 are polished while the outer circumferential edge surface of the glass plate 1 is held in a holding hole provided in a polishing carrier of the double-side polishing apparatus. The first polishing is performed in order to remove blemishes and strain remaining on the ground main surfaces or adjust minute unevenness (micro-waviness, roughness) remaining on the surfaces.
In the first polishing processing, the glass plate 1 is polished using a double-side polishing apparatus having a configuration similar to that of the above-described double-side grinding apparatus that is used in the grinding processing with fixed abrasive particles, while a polishing slurry is provided. In the first polishing processing, a polishing slurry containing loose abrasive particles is used. Cerium oxide abrasive particles, zirconia abrasive particles, or the like are used as loose abrasive particles used in the first polishing, for example. Similar to the double-side grinding apparatus, the glass plate 1 is also held between the upper surface plate and the lower surface plate in the double-side polishing apparatus. Flat polishing pads (resin polishers, for example) having an annular shape overall are attached to the upper surface of the lower surface plate and the bottom surface of the upper surface plate. The glass plate 1 and the surface plates are moved relative to each other by moving one or both of the upper surface plate and the lower surface plate, and thereby the two main surfaces of the glass plate 1 are polished. The size of polishing abrasive particles is preferably in a range of 0.5 to 3 μm in terms of an average particle diameter (D50).
The glass plate 1 may be chemically strengthened after the first polishing. In this case, a melt in which potassium nitrate and sodium nitrate are mixed, for example, can be used as a chemical strengthening liquid, and the glass plate 1 is immersed in the chemical strengthening liquid. Accordingly, it is possible to form a compressive stress layer on the surface of the glass plate 1 through ion exchange.
Then, the second polishing is performed on the glass plate 1. The second polishing processing is performed in order to mirror-polish the main surfaces. A double-side polishing apparatus having a configuration that is similar to that of the double-side polishing apparatus used in the first polishing is used in the second polishing as well. Specifically, the main surfaces on both sides of the glass plate 1 are polished while the outer circumferential edge surface of the glass plate 1 is held in a holding hole provided in a polishing carrier of the double-side polishing apparatus. The second polishing processing differs from the first polishing processing in that the type and particle size of loose abrasive particles are different, and the hardness of the resin polishers is different. It is preferable that the hardness of a resin polisher is smaller than that in the first polishing processing. A polishing liquid containing colloidal silica as the loose abrasive particles is supplied between the polishing pads of the double-side polishing apparatus and the main surfaces of the glass plate 1, and the main surfaces of the glass plate 1 are polished, for example. The size of polishing abrasive particles used in the second polishing is preferably in a range of 5 to 50 nm in terms of an average particle diameter (d50). It is preferable that the roughness of the pair of main surfaces of the glass plate 1 obtained after the second polishing is 0.2 nm or less in terms of the arithmetic average roughness Ra (JIS B0601 2001). The surface roughness can be measured through AFM, for example.
Whether or not chemical strengthening processing is to be carried out need only be selected as appropriate in consideration of the composition of the glass and how necessary chemical strengthening processing may be therefor. Also, other polishing processing may be further added in addition to the first polishing processing and the second polishing processing, or processing for polishing two main surfaces may be completed through a single polishing process. Also, the order of the above-described processes may be changed as appropriate.
In this manner, it is possible to manufacture a magnetic-disk glass substrate that satisfies the conditions required for a magnetic-disk glass substrate by manufacturing the glass plate 1 provided with the chamfered surfaces 5 on edge surfaces by irradiating the edge surfaces with the laser beam L (diffused light L2) described above, and then grinding or polishing the main surfaces of the glass plate 1.
Thereafter, a magnetic disk is manufactured by forming a magnetic film on at least a main surface of the magnetic-disk glass substrate.
Note that edge surface polishing for polishing edge surfaces (the inner circumferential edge surface and/or the outer circumferential edge surface) of the glass plate 1 may be performed after the chamfered surfaces 5 have been formed by irradiating the edge surfaces with the laser beam L (diffused light L2).
Even if such edge surface polishing is performed, an arithmetic average roughness Ra of an edge surface of the glass plate 1 provided with a chamfered surface 5 through irradiation with the laser beam L can be set to 50 nm or less and/or Rz can be set to 500 nm or less, and thus it is possible to shorten the time required for edge surface polishing.
Edge surface polishing may be performed using a polishing brush method in which polishing is performed using a polishing brush while loose abrasive particles are supplied to edge surfaces. However, in order to increase production efficiency, it is preferable to grind or polish the main surfaces of the glass plate 1 without performing edge surface polishing. That is to say, it is preferable to grind or polish the main surfaces of the glass plate 1 while maintaining the surface roughness of an edge surface of the glass plate 1 at the surface roughness of the edge surface obtained through irradiation with the laser beam L. Note that, because the surface roughness of an edge surface formed through irradiation with the laser beam L performed in this embodiment is low, there are cases where the formation of the chamfered surface 5 also serves as edge surface polishing. In this case, the above-described edge surface polishing refers to additional edge surface polishing other than edge surface polishing performed simultaneously with the formation of the chamfered surface 5.
Note that additional edge surface polishing is preferably performed before first polishing is performed. If additional edge surface polishing is performed after first polishing, the polished main surfaces may be scratched. Also, additional edge surface polishing may be performed before or after processing for grinding main surfaces is performed.
It is possible to use amorphous glass such as aluminosilicate glass, soda lime glass, or borosilicate glass as the glass material of the glass plate 1 and the glass blank 2, which is a base of the glass plate 1. In particular, the glass material is preferably amorphous glass in that it is possible to produce a magnetic-disk glass substrate having excellent strength and having main surfaces with excellent flatness. Also, it is preferable that the glass transition temperature Tg of the glass plate 1 and the glass transition temperature Tg of the glass blank 2 are preferably in a range of 450° C. to 850° C. so that the glass plate 1 and the glass blank 2 can withstand heating when forming a magnetic film.
Whether or not luminous flux is blocked by an annular glass blank when irradiation conditions under which the inner circumferential edge surface of the glass blank was irradiated with the laser beam L were changed in various ways was checked through simulation.
(Simulation Conditions)
As can be seen from Table 1, it was found that, even in a case where the luminous flux is blocked under the conditions in which conventional convergent light is used, use of the diffused light enables an inner circumferential edge surface to be irradiated with the laser beam without blocking the luminous flux.
When the distance from the irradiation position to the light concentration position exceeds 25 mm, the focal point in a plan view is located outward of the inner diameter end of the glass blank in the radial direction. That is to say, the focal point is located outward of the above-described “position A” in the radial direction. In such a case, the positions of the laser oscillator and/or optical system components such as lenses can be relatively easily distanced from a glass blank that is to be processed. Such a case is preferable because the degree of freedom in designing an auxiliary device that loads/unloads the glass blank to/from the photoirradiation device is increased, for example.
Chamfering processing was actually performed on inner circumferential edge surfaces of glass blanks under conditions 10, 12, and 14 in Table 1. Chamfering processing was performed in the same manner as in Experiment Example 1, except that the shape of the annular glass blank was changed such that the thickness thereof was 0.7 mm. Amorphous aluminosilicate glass having a glass transition point of about 500° C. was used as a material of the glass blank. A CO2 laser was used as the laser beam L. Before irradiation with the laser beam L, the entirety of the main surfaces of the glass blank 2 were heated using an infrared heater. Other conditions and methods for carrying out irradiation were adjusted as appropriate with reference to the above-described embodiment, such that an inner circumferential edge surface obtained after chamfering processing had a cross-sectional shape similar to that in
As a result, the inner circumferential edge surface of the obtained glass plate had a cross-sectional shape similar to that shown in
As described above, although a method for manufacturing a glass plate, a method for manufacturing a magnetic-disk glass substrate, a method for manufacturing a magnetic disk, and an apparatus for processing a glass plate according to the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and it will be appreciated that various improvements and modifications can be made without departing from the gist of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1-2021-00461 | Jan 2021 | VN | national |
This U.S. National stage application of International Patent Application No. PCT/JP2022/003442, filed on Jan. 28, 2022, which, in turn, claims priority to Japanese Patent Application No. 1-2021-00461, filed in Vietnam on Jan. 28, 2021. The entire contents of Vietnamese Patent Application No. 1-2021-00461 are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/003442 | 1/28/2022 | WO |
