Glass plate measuring device, glass plate measuring method, and glass plate manufacturing method

Abstract

The present invention comprises a platform (2) made of natural stone substantially free of crystal, and an optical measuring mechanism (3) utilizing irradiation and reflection of light in measurement, and is configured such that, when a glass plate (G) is placed on a surface (2a) of the platform (2), the optical measuring mechanism (3) irradiates light from the surface (2a) of the glass plate (G) toward the platform (2), and reflects the light, thereby measuring the glass plate (G).

Description

Technical Field

[0001] The present invention relates to a technique for measuring a glass plate by using an optical measuring mechanism in a state where a glass plate is placed on a stage. Background Art

[0002] As is known, in glass plate manufacturing plants, it is customary to measure glass plates after they are manufactured for the purpose of quality control, etc. As an example, Patent Document 1 discloses measuring the warpage of a glass plate placed on a surface of a platform.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-87382 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As a platform for measuring the warpage of glass plates, ceramic platforms are widely used. However, it is difficult to manufacture a large-sized platform because of the need for firing. Therefore, it is gradually unable to cope with the large-sized glass plates in recent years. From this point of view, the use of a platform made of natural stone such as granite is studied.

[0008] Under such circumstances, the inventors of the present invention have repeatedly conducted in-depth studies and found that the platform made of natural stone such as granite, which has been used in the measurement of glass plates, is not suitable for measuring glass plates using an optical measuring mechanism that uses irradiation and reflection of light in the measurement because the diffuse reflection of light on the surface is significant. In other words, it was found that such an optical measuring mechanism cannot stably detect the light reflected on the surface of the platform, and not only the measurement accuracy is deteriorated, but also sometimes it is impossible to measure. Therefore, although such an optical measuring mechanism has a higher measurement accuracy than a mechanical or contact measuring mechanism, there is a problem that it cannot be appropriately used for measuring glass plates using a platform made of natural stone.

[0009] From the above viewpoints, the present invention aims to make it less susceptible to the influence of diffuse reflection of light when measuring a glass plate placed on the surface of a platform made of natural stone, and to appropriately use an optical measuring mechanism that utilizes irradiation and reflection of light in the measurement.

[0010] Solutions to Solve Problems

[0011] In order to solve the above-mentioned problems, the inventors of the present invention have further advanced their research and found that the reason why the surface of the platform composed of natural stone produces obvious diffuse reflection of light is that the platform substantially contains crystals. Here, substantially containing crystals means that the surface of the platform is observed using an electron microscope (EPMA JXA-8100 manufactured by JEOL Ltd.), the element distribution of Si is observed to confirm the area with relatively strong Si intensity, and when the corresponding backscattered electron composition image (backscattered electron image; in the case of the platform, since Si has a low atomic number, the black part can be seen) is qualitatively analyzed using EDX (energy dispersive X-ray analysis) and WDX (wavelength dispersive X-ray analysis), only Si and O peaks are present.

[0012] The first aspect of the present invention completed based on the findings of the present inventors is a glass plate measuring device, which includes a platform for placing a glass plate and an optical measuring mechanism that utilizes irradiation and reflection of light in measurement, wherein the optical measuring mechanism irradiates light from the surface side of the glass plate toward the platform and reflects the light to measure the glass plate when the glass plate is placed on the surface of the platform, and is characterized in that the platform is made of natural stone that does not substantially contain crystal. Here, substantially containing no crystal means that the surface of the platform is observed using an electron microscope (EPMA JXA-8100 manufactured by JEOL Ltd.), the element distribution of Si is observed, and a region with a high relative intensity of Si is confirmed, and when the corresponding backscattered electron composition image (backscattered electron image) is qualitatively analyzed using EDX (energy dispersive X-ray analysis) and WDX (wavelength dispersive X-ray analysis), there are no peaks of Si and O.

[0013] According to the device, since the platform is made of natural stone that does not substantially contain crystals, the surface of the platform is in a state where diffuse reflection of light is not likely to occur. Therefore, when a glass plate is placed on the surface of the platform and an optical measuring mechanism that utilizes irradiation and reflection of light is used to measure the glass plate, the negative effects caused by diffuse reflection of light are not likely to occur. Therefore, when measuring the glass plate, although a platform made of natural stone is used, this optical measuring mechanism can be appropriately used. In addition, since this optical measuring mechanism has a higher measurement accuracy than a mechanical or contact measuring mechanism, it can measure the glass plate with high accuracy. Moreover, since the platform is made of natural stone, the size can be set to be large, and it can appropriately cope with the large-scale glass plates in recent years.

[0014] In the device, the platform may also be made of Kanur or Indian Black.

[0015] That is, among various natural stones, Kanol and Indian Black both meet the above requirement of not containing crystals substantially, and are excellent in suppressing diffuse reflection of light. Therefore, as long as a platform is formed using either Kanol or Indian Black, an optical measurement mechanism that uses irradiation and reflection of light in measurement can be appropriately used for measuring a glass plate.

[0016] In the above device, a groove capable of allowing air to flow between the platform and the glass sheet when the glass sheet is placed on the surface of the platform may be formed on the surface of the platform.

[0017] Thus, when the glass plate is placed on the surface of the platform, even if an inappropriate amount of air is accumulated between the surface of the platform and the glass plate, the air will be released through the groove between the two. Therefore, the glass plate is placed on the surface of the platform in its original shape, and the operation of placing the glass plate can be smoothly performed. In addition, when the glass plate is peeled off from the platform, the glass plate may be firmly attached to the surface of the platform and damaged, but in the structure here, the air can flow freely between the two through the groove. Therefore, it is possible to avoid the situation where the glass plate is firmly attached to the surface of the platform, and the operation of removing the glass plate can be smoothly performed.

[0018] In the above device, the optical measuring mechanism may be a laser rangefinder.

[0019] Thus, when measuring a glass plate placed on the surface of a platform made of natural stone, the laser distance meter can be used appropriately. In addition, the laser distance meter has high measurement accuracy, so the high-precision measurement of the glass plate can be reliably achieved.

[0020] In the above-mentioned apparatus, as the measurement of the glass plate, measurement of warpage of the glass plate may be performed.

[0021] In this manner, even though a platform made of natural stone is used, the warpage of the glass plate can be appropriately measured by an optical measurement mechanism that utilizes irradiation and reflection of light for measurement.

[0022] Instead of or in addition to the configuration of the device, as the measurement of the glass plate, the thickness of the glass plate may be measured.

[0023] In this manner, even though a platform made of natural stone is used, the thickness of the glass plate can be appropriately measured by an optical measuring mechanism that utilizes irradiation and reflection of light for measurement.

[0024] In addition, the second aspect of the present invention is a glass plate measuring method, characterized in that a platform made of natural stone that essentially does not contain crystal and an optical measuring mechanism that utilizes irradiation and reflection of light during measurement are used. When a glass plate is placed on the surface of the platform, the optical measuring mechanism irradiates light from the surface side of the glass plate toward the platform and reflects the light to measure the glass plate.

[0025] According to this method, as in the case of the device described above, although a platform made of natural stone is used, it is possible to measure the glass plate with high accuracy by appropriately using an optical measurement mechanism that utilizes light irradiation and reflection in the measurement. Furthermore, the size of the platform can be increased to cope with the increase in the size of the glass plate.

[0026] In addition, the glass plate measuring method may be performed as one step in a glass plate manufacturing method.

[0027] Effects of the Invention

[0028] According to the present invention, when measuring a glass plate placed on the surface of a platform made of natural stone, the influence of diffuse reflection of light is less likely to occur, so an optical measuring mechanism using irradiation and reflection of light in measurement can be appropriately used. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a perspective view showing the entire structure of the glass plate measuring device according to the embodiment of the present invention.

[0030] Figure 2 It is a top view showing a platform which is a component of the glass plate measuring device according to the embodiment of the present invention.

[0031] Figure 3 This is an enlarged longitudinal sectional side view of a main part for explaining the operation of the glass plate measuring device according to the embodiment of the present invention.

[0032] Figure 4 It is a plan view for explaining the operation of the glass plate measuring device according to the embodiment of the present invention.

[0033] Figure 5 This is an enlarged longitudinal sectional front view of a main part for explaining the operation of the glass plate measuring device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0035] Figure 11 is a perspective view showing the overall structure of a glass plate measuring device 1 according to an embodiment of the present invention. As shown in the figure, the glass plate measuring device 1 includes a rectangular platform 2 on which a glass plate G is placed in a horizontal position and a laser rangefinder 3 as an optical measuring mechanism disposed on the surface side (upper side) of the glass plate G as main components.

[0036] The length of the platform 2 in the longitudinal direction (the AA direction in the figure) is 1000 to 1400 mm, and the length in the lateral direction (the BB direction in the figure) is 1000 to 1400 mm. The thickness of the platform 2 is 80 to 250 mm, and preferably 80 to 150 mm. In the example, the platform 2 is mounted and fixed on a support platform 5 fixedly arranged at the upper end of the frame 4. The support platform 5 can be made of metal, natural stone or artificial stone, and is preferably made of natural stone or artificial stone. The longitudinal length and lateral length of the support platform 5 are longer than those of the platform 2 and the thickness is the same as that of the platform 2.

[0037] The length of the glass plate G in the longitudinal direction is 30 to 1300 mm, the length in the lateral direction is 30 to 1300 mm, and the thickness is 30 to 1100 μm (preferably the upper limit is 400 μm). In this figure, the warpage generated in the glass plate G is exaggeratedly shown.

[0038] The laser rangefinder 3 has an irradiation part 3a for irradiating laser light toward the platform 2 and a light receiving part 3b for receiving reflected laser light. In addition, the laser rangefinder 3 can move in the longitudinal direction and the transverse direction on a plane parallel to the surface 2a of the platform 2. In detail, prismatic side members 6 fixed on the support platform 5 and extending in the transverse direction are respectively arranged on both sides of the longitudinal direction of the platform 2, and transverse guide rails 7 extending in the transverse direction are respectively fixed to the pair of side members 6. Sliders 8 that can slide in the transverse direction are respectively held on the pair of transverse guide rails 7, and pillars 9 are respectively erected and fixed on the upper parts of the pair of slides 8. A box-shaped body 10 that extends in the longitudinal direction and is open at the bottom is mounted on the upper end of the pair of pillars 9. A longitudinal guide rail 11 extending in the longitudinal direction is fixed inside the box-shaped body 10, and the laser rangefinder 3 is held in the longitudinal guide rail 11 in a manner that can slide in the longitudinal direction. Therefore, the laser rangefinder 3 is guided by the transverse guide rail 7 to move in the transverse direction, and is guided by the longitudinal guide rail 11 to move in the longitudinal direction. It should be noted that the drive mechanism for moving the laser rangefinder 3 in the lateral direction and the drive mechanism for moving the laser rangefinder 3 in the longitudinal direction are both composed of a combination of various motors and ball screw mechanisms, fluid pressure cylinders such as air cylinders, etc. (not shown).

[0039] like Figure 1 as well as Figure 2As shown, a plurality of grooves 2m extending in the lateral direction are formed on the surface of the platform 2. The width (longitudinal length) W of these grooves 2m is 0.5 to 3 mm (preferably 0.5 to 2 mm). In addition, the length (lateral length) of these grooves 2m is the same as the lateral length of the platform 2 and penetrates the platform 2. The depth of these grooves 2m is 0.5 to 3 mm (preferably 0.5 to 2 mm). The pitch P between these grooves 2m is 50 to 200 mm (preferably 50 to 100 mm).

[0040] Moreover, the platform 2 is a stone platform made of natural stone and is made of Karnool or Indian black. The reason for using Karnool or Indian black among various natural stones is as follows. That is, as a result of repeated and in-depth research by the present inventors, it was found that a platform made of natural stone used in the measurement of a glass plate in the past produced significant diffuse reflection of light on the surface, so a light measurement mechanism that uses light irradiation and reflected light in the measurement, such as the laser rangefinder 3, could not be used properly. Moreover, as a result of the present inventors conducting experiments on various natural stones, it was found that if the platform is made of natural stone that substantially does not contain quartz, diffuse reflection of light on the surface can be suppressed and the light measurement mechanism can be used properly. Here, the meaning of substantially not containing quartz is to observe the surface of the platform using an electron microscope (EPMA JXA-8100 manufactured by JEOL Ltd.), observe the elemental distribution of Si, and confirm regions with a relatively strong intensity of Si, and not have peaks of Si and O when qualitatively analyzing the corresponding backscattered electron image (in the case of the platform, since Si has a low atomic number, black portions can be seen) using EDX (energy-dispersive X-ray analysis) and WDX (wavelength-dispersive X-ray analysis). Karnool and Indian black satisfy the requirement of "substantially not containing quartz" here. It should be noted that when only having peaks of Si and O in the above qualitative analysis, it is considered "substantially containing quartz", and such natural stones are not used in the platform 2 of the present invention.

[0041] Figure 3 The situation of measuring the warpage (warpage amount) and thickness of the glass plate G using the laser rangefinder 3 is illustrated. It should be noted that the measurement method shown in this figure is a measurement method based on the triangulation method. In addition, the irradiation unit 3a shown in this figure includes a projection lens and a laser diode above it, and the light receiving unit 3b includes a light receiving lens and a one-dimensional light receiving element (CMOS or PSD) above it.

[0042] As shown in the figure, when warping occurs on the glass plate G at the reflection position of the laser L irradiated from the irradiation unit 3a, the three laser reflected lights L1, L2, and L3 are received by the light receiving unit 3b. Specifically, the first laser reflected light L1 reflected from the surface (upper surface) Ga of the glass plate G, the second laser reflected light L2 reflected from the back surface (lower surface) Gb of the glass plate G, and the third laser reflected light L3 reflected from the surface (upper surface) 2a of the stage 2 are received by the light receiving unit 3b.

[0043] Here, when measuring the warping of the glass plate G, as a first method, the first laser reflected light L1 and the third laser reflected light L3 received by the light receiving unit 3b are read by a one-dimensional light receiving element in the light receiving unit 3b, and the distance Lv (vertical distance) from the surface Ga of the glass plate G to the surface 2a of the stage 2 is obtained based on the principle of triangulation. Then, based on this distance Lv, the warping (warping amount) of the glass plate G at the measurement point is estimated. This estimation is performed, for example, by subtracting the designed thickness of the glass plate G from the above-mentioned distance Lv. Additionally, as a second method, the second laser reflected light L2 and the third laser reflected light L3 are read by a one-dimensional light receiving element in the light receiving unit 3b to obtain the distance Lw from the back surface Gb of the glass plate G to the surface 2a of the stage 2, and this distance Lw is used as the warping amount of the glass plate G at the measurement point. Moreover, as a third method, the first laser reflected light L1 is read by a one-dimensional light receiving element in the light receiving unit 3b to obtain the distance Lx from the surface Ga of the glass plate G to the ideal plane of the surface of the glass plate G (the surface in the case where the glass plate G does not have bending, undulation, etc.), and this distance Lx is used as the warping amount of the glass plate G at the measurement point. In this case, it is also possible to obtain the distance Ly from the surface 2a of the stage 2 to the ideal plane of the surface of the stage 2 (the surface in the case where no warping occurs on the surface of the stage 2) based on the third laser reflected light L3, estimate the difference between this distance Ly and the above-mentioned distance Lx, and use this difference as the warping amount at the measurement point.

[0044] It should be noted that the methods for determining the warpage amount in the first, second, and third methods described here are merely examples. Therefore, in the first, second, and third methods, as long as the method is based on the laser reflected light selected from the first, second, and third laser reflected lights L1, L2, and L3 in the same manner as described above, the warpage amount of the glass plate G can also be measured by a determination method other than the above-mentioned examples. For example, in the above-mentioned method, the first laser reflected light L1 to the third laser reflected light L3 are simultaneously received by the light receiving unit 3b, but they can also be received separately. Specifically, in the first method, after the third laser reflected light L3 is received by the light receiving unit 3b in a state where the glass plate G is not placed on the platform 2, the first laser reflected light L1 reflected on the surface (upper surface) Ga of the glass plate G can be received in a state where the glass plate G is placed on the platform 2. Alternatively, if it is the second method, after the third laser reflected light L3 is received by the light receiving unit 3b when the glass plate G is not placed on the platform 2, the second laser reflected light L2 reflected by the back side (lower surface) Gb of the glass plate G is received when the glass plate G is placed on the platform 2.

[0045] In addition, when measuring the thickness of the glass plate G, the first laser reflected light L1 and the second laser reflected light L2 received by the light receiving unit 3b are read by the one-dimensional light receiving element in the light receiving unit 3b, and the distance Lz (the distance in the vertical direction) from the front surface Ga to the back surface Gb of the glass plate G is obtained by the principle of triangulation. This distance Lz becomes the thickness of the glass plate G at the measurement point. It should be noted that in the first method for measuring the warpage of the glass plate G described above, the thickness Lz measured here can also be used instead of the designed thickness.

[0046] As described above, the laser distance meter 3 of the glass plate measuring device 1 can be moved in the horizontal direction and in the vertical direction. Figure 4As shown, the glass plate measuring device 1 measures the warpage amount and thickness of the entire area of ​​the glass plate G by scanning the laser light L from the irradiation part 3a of the laser rangefinder 3 along a plurality of parallel straight lines (straight lines corresponding to the longitudinal guide rails 11) 12 extending in the longitudinal direction. In this case, it is preferable not to perform the measurement when the measurement point is located on the groove 2m of the platform 2. It should be noted that the lateral interval C of the scanned straight lines 12 is preferably 200 mm or less, and more preferably 150 mm or less. By performing such scanning, the distribution of the warpage and the deviation of the thickness of the entire area of ​​the glass plate G can be known. It should be noted that the present invention is not limited to the structure in which the laser light L from the irradiation part 3a of the laser rangefinder 3 is scanned, and it can also be set as a structure in which the laser rangefinder 3 measures the warpage amount and thickness of the glass plate G at a predetermined interval while moving. In the latter structure, the longitudinal measurement interval is preferably 200 mm or less, and more preferably 50 mm or less. The lateral measurement interval is preferably 200 mm or less, and more preferably 150 mm or less.

[0047] Next, the effects of the glass plate measuring device 1 described above will be described.

[0048] According to the glass plate measuring device 1, the platform 2 is made of canol or Indian black which does not substantially contain crystal, so the surface 2a of the platform 2 is in a state where diffuse reflection of light is not likely to occur. Therefore, when the laser rangefinder 3 is used to measure the warpage and thickness of the glass plate G with the glass plate G placed on the surface 2a of the platform 2, the negative effects caused by diffuse reflection of light are not likely to occur. Therefore, although the platform 2 is made of natural stone, the laser rangefinder 3 can be appropriately used in the measurement of the glass plate G. In addition, since the laser rangefinder 3 has a higher measurement accuracy than a mechanical or contact measurement mechanism, the glass plate G can be measured with high accuracy. In addition, since the platform 2 is made of natural stone, it can be enlarged, and it can appropriately cope with the large-scale glass plates G in recent years.

[0049] In addition, a plurality of grooves 2m are formed on the surface 2a of the platform 2, so that the glass plate G placed on the surface 2a of the platform 2 can be prevented from being in an undesirable deformed state. Specifically, when the glass plate G is placed, even if an undesirable air accumulation is generated between the surface 2a of the platform 2 and the glass plate G, the glass plate G is prevented from being in an undesirable deformed state. Figure 5In order to prevent the improper warping Gc as shown by the dotted line in the figure, the air can also be released from between the platform 2 and the glass plate G through the groove 2m. Therefore, the glass plate G is placed on the surface 2a of the platform 2 while maintaining its original shape as shown by the solid line in the figure. In addition, the operation for placing the glass plate G can also be smoothly performed. In addition, when the glass plate G is peeled off from the platform 2, the glass plate G may be firmly attached to the surface 2a of the platform 2 and damaged, but according to the structure here, the air can flow freely between the platform 2 and the glass plate G through the groove 2m. Therefore, it is possible to avoid the situation where the glass plate G is firmly attached to the surface 2a of the platform 2. In addition, the operation for removing the glass plate G can also be smoothly performed.

[0050] In addition, the surface of the platform was previously considered as a reference surface (ideal plane) without deformation. However, the inventors of the present invention determined that the situation in which the surface of the platform 2 is curved, undulated, etc. should be considered. After considering this situation, the inventors of the present invention found that the amount of warping of the glass plate G obtained by measuring the laser reflected light (the third laser reflected light L3 described above) reflected by the surface 2a of the platform 2 is the amount of warping of the glass plate G after the curvature of the surface 2a of the platform 2 is corrected. Therefore, the amount of warping of the glass plate G obtained based on the first and third laser reflected lights L1 and L3 described above and the amount of warping of the glass plate G obtained based on the second and third laser reflected lights L2 and L3 are both the amount of warping of the glass plate G after the curvature of the surface 2a of the platform 2 is corrected. In addition, the surface Ga of the glass plate G is a surface on which manufacturing-related processing such as film forming processing is performed in the post-process, so if the deviation in the thickness of the glass plate G is considered, it becomes important to measure the amount of warping of the surface Ga of the glass plate G. Therefore, if the warping amount of the glass plate G is measured based on the first and third laser reflected lights L1 and L3 described above, the warping amount of the surface Ga of the glass plate G after the warping of the surface 2a of the platform 2 is corrected can be obtained. In the warping amount measurement result in this case, the error caused by the warping of the surface 2a of the platform 2 is suppressed.

[0051] Next, a glass plate measuring method according to an embodiment of the present invention is described. This glass plate measuring method is the same as the description already described, but uses a platform 2 made of canol or Indian black that does not substantially contain crystal and a laser rangefinder 3. Then, in a state where a glass plate G is placed on the surface 2a of the platform 2, the irradiation unit 3a of the laser rangefinder 3 irradiates the laser L from the surface Ga side of the glass plate G toward the platform 2, and the light receiving unit 3b of the laser rangefinder 3 receives the laser reflected light L1, L2, and L3, thereby measuring the warpage and thickness of the glass plate G. This glass plate measuring method can also be added to the manufacturing process of the glass plate. In this case, the glass plate measuring method is performed as one process of the glass plate manufacturing method.

[0052] The present invention is not limited to the embodiments described above, and various modifications as described below can be made.

[0053] In the above-described embodiment, the platform 2 made of Carnot or Indian black was used, but as long as the requirement of substantially not containing quartz is satisfied, a platform made of other natural stones can also be used. The natural stone preferably substantially does not contain quartz. Thereby, diffuse reflection of light on the surface of the platform is less likely to occur.

[0054] In the above-described embodiment, a plurality of grooves 2m extending in the lateral direction are formed on the surface of the platform 2, but grooves extending in the longitudinal direction can also be additionally formed. In addition, if it is a platform used only for small-sized glass plates, the number of grooves can also be one. Or instead of the plurality of grooves 2m extending in the lateral direction, grooves extending in the longitudinal direction can be formed. In the above-described embodiment, the length of the groove 2m is set to be the same as the length of the platform 2, but as long as a part of the groove 2m extends out of the placed glass plate, the length of the groove 2m can also be shorter than the length of the platform 2.

[0055] In the above-described embodiment, the triangulation method based on the laser rangefinder 3 as an optical measurement mechanism is adopted, but this measurement method can also be other methods such as the phase difference ranging method. In addition, as long as light irradiation and reflection are utilized in the measurement, it can also be an optical measurement mechanism other than the laser rangefinder 3.

[0056] In the above-described embodiment, by using Figure 4 the scanning of the primary light shown, the warpage of the glass plate G and the thickness of the glass plate G are measured, but the two can also be measured by using separate light scans, or only either one of the two can be measured.

[0057] Description of reference numerals

[0058] 1 Glass plate measuring device

[0059] 2 Platform

[0060] 2a Surface of the platform

[0061] 2m Groove of the platform

[0062] 3 Laser rangefinder (optical measurement mechanism)

[0063] 3a Irradiation part

[0064] 3b Light receiving part

[0065] G Glass plate

[0066] Ga Surface of the glass plate

[0067] L Laser

[0068] L1 First laser reflected light

[0069] L2 Second laser reflected light

[0070] L3 The third laser reflected light.

Claims

1. A glass plate measuring device comprising a platform made of natural stone on which a glass plate is placed and an optical measuring mechanism utilizing irradiation and reflection of light in measurement, wherein the optical measuring mechanism irradiates light from the surface side of the glass plate toward the platform and reflects the light to measure the glass plate when the glass plate is placed on the surface of the platform. It is characterized in that The natural stone constituting the platform contains substantially no crystals.

2. The glass plate measuring device according to claim 1, It is characterized in that The platform is made of Kanur or Indian Black.

3. The glass plate measuring device according to claim 1 or 2, It is characterized in that A groove is formed on the surface of the platform so as to allow air to flow between the platform and the glass plate when the glass plate is placed on the surface of the platform.

4. The glass plate measuring device according to claim 1 or 2, It is characterized in that The optical measuring mechanism is a laser rangefinder.

5. The glass plate measuring device according to claim 1 or 2, It is characterized in that As the measurement of the glass plate, the warpage of the glass plate was measured.

6. The glass plate measuring device according to claim 1 or 2, It is characterized in that As the measurement of the glass plate, the thickness of the glass plate was measured.

7. A method for measuring a glass plate, comprising: using a platform made of natural stone and an optical measuring mechanism that utilizes irradiation and reflection of light in measurement, wherein the optical measuring mechanism irradiates light from the surface side of the glass plate toward the platform and reflects the light to measure the glass plate when a glass plate is placed on the surface of the platform. It is characterized in that The natural stone constituting the platform contains substantially no crystals.

8. A method for manufacturing a glass sheet, It is characterized in that The method comprises the step of executing the glass plate measuring method according to claim 7.

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