Method for measuring flatness of glass plate

Abstract

To provide a method for measuring the flatness of a glass plate capable of measuring the flatness of even a thin glass plate with high accuracy.SOLUTION: In the flatness measuring method of the glass plate G for measuring the flatness of the glass plate G, the glass plate G is curved and arranged in a convex or concave arc shape, a stylus 13 of a measuring device 10 is brought into contact with a surface of the glass plate G, and the glass plate G and the stylus 13 are relatively moved in a measuring direction X crossing a curving direction Y of the glass plate G and along a main surface of the glass plate G.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the flatness of a glass plate. [Background technology]

[0002] Patent Document 1 discloses a technique in which a glass plate is irradiated with a pattern having periodic light and dark from a surface light source, the pattern that passes through the glass plate is imaged with a CCD camera, and a signal processing device evaluates the surface shape of the glass plate based on the shift in the light and dark cycle in the image. Another known method for measuring the flatness of a glass plate is a contact type in which a contact measuring instrument is moved while in contact with the surface of the glass plate, and the contact measuring instrument measures the irregularities in the surface shape of the glass plate to determine the flatness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3411829 Summary of the Invention [Problem to be solved by the invention]

[0004] In the contact-type flatness measurement method, the glass plate is placed on a surface plate and the stylus of the contact-type measuring instrument is moved while in contact with the surface. However, in the case of thin glass plates that are easily deformed, with a thickness of about 0.5 mm or less, the glass plate placed on the surface plate is affected by the surface shape of the surface plate, making it difficult to measure the flatness of the glass plate itself.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for measuring the flatness of a glass plate, which is capable of measuring the flatness of even a thin glass plate with high accuracy. [Means for solving the problem]

[0006] The present invention comprises the following configurations. A method for measuring the flatness of a glass plate, comprising: The glass plate is arranged so as to be curved in a convex or concave arc shape, A stylus of a measuring device is brought into contact with the surface of the glass plate, The glass plate and the stylus are moved relative to each other in a direction that intersects with the curvature direction of the glass plate and is along the main surface of the glass plate. Method for measuring the flatness of glass plates. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a method for measuring the flatness of a glass plate, which is capable of measuring the flatness of even a thin glass plate with high precision. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic side view of a jig on which a glass plate is placed, illustrating a measuring method according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a graph showing the flatness of a glass plate measured by the measurement method according to the first embodiment. [Figure 4] FIG. 4 is a graph showing the flatness of a glass plate measured by placing it on a surface plate. [Figure 5] FIG. 5 is a schematic front view of a jig on which a glass plate is placed, illustrating a measuring method according to the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] (First embodiment) First, the first embodiment will be described. Fig. 1 is a schematic side view of a jig 20 on which a glass plate G is placed, illustrating a measuring method according to the first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1.

[0011] 1 and 2, the flatness measurement method according to the first embodiment is a method for measuring the flatness of the surface of a glass plate G. The glass plate G to be measured is a thin glass plate, for example, having a thickness of about 0.5 mm or less, and is a glass plate used for flat panel displays (FPDs) such as LCDs (Liquid Crystal Displays) and OLEDs (Organic Light-Emitting Diodes). The glass plate G is formed in a rectangular shape in a plan view, having a pair of side edges Ga and a pair of end edges Gb.

[0012] The flatness measurement method according to the first embodiment uses a contact-type measuring device (for example, SURFCOM manufactured by Tokyo Seimitsu Co., Ltd.) 10. This measuring device 10 is equipped with a probe 11 having a stylus 13 at its tip, and this probe 11 is supported by a device body (not shown). This measuring device 10 measures the flatness of the surface of the object by moving the probe 11 in the longitudinal direction relative to the device body while keeping the stylus 13 in contact with the surface of the object, thereby moving the stylus 13 relative to the object.

[0013] In the first embodiment, a jig 20 is used when measuring the flatness of a glass plate G. The jig 20 includes a pair of support members 23 and a plurality of clips 25.

[0014] The support members 23 are formed in a plate or block shape, and their upper portions are curved so as to protrude in an arc shape along the longitudinal direction to form curved portions 21. These support members 23 are arranged on the upper surface of the base 27 at intervals from each other.

[0015] Clip 25 is formed in a U-shape and has locking pieces 31 and holding pieces 33. Clip 25 is attached to curved portion 21 of support member 23 by locking locking pieces 31 to the side of support member 23, with holding pieces 33 positioned on the upper surface side of support member 23. These clips 25 are attached to support member 23 at multiple locations spaced apart along curved portion 21.

[0016] Next, the case of measuring the flatness of the glass plate G will be described. (Placement process) First, both side edge portions Ga of the glass plate G to be measured are placed on the curved portions 21 of the support members 23 that are arranged at an interval on the base 27. In this way, the glass plate G is stretched across the support members 23. Then, the glass plate G is deformed along the curved portions 21 of the support members 23 and curved into a convex arc shape.

[0017] Next, the clips 25 are attached from the sides of the support members 23. As a result, both side edge portions Ga of the glass sheet G are sandwiched and held between the holding pieces 33 of these clips 25 and the curved portions 21 of the support members 23. Therefore, the glass sheet G is maintained in a curved state in a convex arc along the curved portions 21.

[0018] (Measurement process) After the glass sheet G is placed on the jig 20, a stylus 13 attached to a probe 11 of the measuring device 10 is brought into contact with the surface of the glass sheet G at a longitudinally intermediate portion along both side edge portions Ga. The probe 11 is then moved to bring the stylus 13 into contact with the top surface of the glass sheet G, while the glass sheet G and the stylus 13 are moved relative to each other in a measurement direction X that intersects with the curvature direction Y of the glass sheet G (see FIG. 1 ) and runs along the main surface of the glass sheet G. This allows the measuring device 10 to measure the irregularities in the surface shape of the glass sheet G and determine its flatness. The measurement direction X, which intersects with the curvature direction Y of the glass sheet G and runs along the main surface of the glass sheet G, is a direction that intersects with both side edge portions Ga of the glass sheet G that is curved and supported by the jig 20. The measurement range in which the stylus 13 comes into contact with the glass sheet G to measure its flatness is a portion other than the area in contact with the support member 23.

[0019] However, excessive curvature of the thin glass plate G may result in damage, whereas insufficient curvature may reduce the reproducibility of flatness measurement and decrease measurement accuracy.

[0020] For this reason, the radius of curvature of the glass sheet G to be curved when measuring the flatness of the glass sheet G is preferably 50 mm or more and 500 mm or less. Bending the glass sheet G with a radius of curvature of 50 mm or more can prevent damage to the glass sheet G due to excessive bending. Bending the glass sheet G with a radius of curvature of 500 mm or less allows for highly accurate measurements with good reproducibility. Note that the radius of curvature of the glass sheet G to be curved when measuring the flatness of the glass sheet G is preferably 100 mm or more and 350 mm or less.

[0021] Here, the flatness of a glass plate G having a plate thickness of 0.2 mm was measured, and the reproducibility of the measurement results was evaluated. The flatness measurement was performed by the measurement method according to the first embodiment, in which the glass plate G was placed on a jig 20 and curved so as to be convex upward, and by a measurement method in which the glass plate G was placed on a surface plate and measured. The radius of curvature of the glass plate G when curved was 300 mm.

[0022] Fig. 3 is a graph showing the flatness of a glass plate G measured by the measurement method according to the first embodiment. Fig. 4 is a graph showing the flatness of a glass plate G placed on a surface plate and measured. Note that Fig. 3 shows the flatness of the glass plate G when the glass plate G is attached to a jig 20 and the flatness is measured three times, and Fig. 4 shows the flatness of the glass plate G placed on a surface plate and the flatness is measured three times.

[0023] As shown in Fig. 3, when a glass plate G was placed on a jig 20 and curved so as to be convex, and the flatness was measured three times, there was no significant deviation in the measurement results, and the measurements were performed with high reproducibility. In contrast, as shown in Fig. 4, when the glass plate G was placed on a surface plate and the flatness was measured three times, the glass plate G was affected by the surface shape of the surface plate, causing deviation in the measurement results, and the flatness could not be measured with good reproducibility. As such, it was found that the measurement method according to this embodiment, in which the glass plate G is curved to measure the flatness, allows the flatness of the glass plate G to be measured with high accuracy and high reproducibility.

[0024] As described above, according to the method for measuring the flatness of a glass sheet G according to the first embodiment, the glass sheet G is curved in an arc shape so as to be convex, and then the glass sheet G and the stylus 13 in contact with the surface of the glass sheet G are moved relative to each other in a measurement direction X that intersects with the curvature direction Y and is along the main surface of the glass sheet G. Therefore, compared to a method in which the glass sheet G is placed on a surface plate and the flatness is measured, the flatness of the thin glass sheet G can be measured with high accuracy without being affected by the surface shape of the surface plate.

[0025] Therefore, the flatness of a glass plate G having a thickness of, for example, 0.5 mm or less, preferably 0.3 mm or less, which is easily affected by the surface shape of a surface plate when placed on the surface plate, can be measured with high accuracy. The lower limit of the thickness of the glass plate G is not particularly limited, but is, for example, 0.1 mm.

[0026] Furthermore, by using the jig 20, the glass plate G can be easily curved and positioned in a convex arc shape suitable for measurement, and the flatness of the thin glass plate G can be measured smoothly.

[0027] (Second embodiment) Next, a second embodiment will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted. Fig. 5 is a schematic front view of a jig 40 on which a glass plate G is placed, illustrating a measuring method according to the second embodiment. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 5. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6.

[0028] 5 to 7, the method for measuring the flatness of a glass plate G according to the second embodiment uses a jig 40 different from that in the first embodiment. The jig 40 includes a pair of support members 43 and a pair of locking members 47.

[0029] The support members 43 are formed in a plate or block shape, and their upper portions are formed as support portions 41 that are linearly formed along the longitudinal direction. These support members 43 are arranged on the upper surface of the base 27 at intervals from each other.

[0030] The locking members 47 are formed in a columnar shape and have locking pins 45 on the sides of their upper ends. These locking members 47 are arranged on the base 27 at intervals between each other in the intermediate portions between the support members 43. These locking members 47 are erected on the base 27 with their locking pins 45 facing each other.

[0031] Next, the case of measuring the flatness of the glass plate G will be described. (Placement process) First, both edge portions Gb of the glass plate G to be measured are placed on the support portions 41 of the support members 43 arranged at intervals on the base 27, and the glass plate G is then stretched across the support members 43.

[0032] Next, the locking members 47 are set upright on the base 27 while the locking pins 45 of the locking members 47 are locked to the side edge portions Ga of the glass plate G. This pulls down and deforms the side edge portions Ga of the glass plate G, causing the glass plate G to bend into a concave arc shape.

[0033] (Measurement process) After the glass sheet G is placed on the jig 40, a stylus 13 attached to a probe 11 of the measuring device 10 is brought into contact with the surface of the glass sheet G at a longitudinally intermediate portion along both side edge portions Ga. The probe 11 is then moved to bring the stylus 13 into contact with the top surface of the glass sheet G, while the glass sheet G and the stylus 13 are moved relative to each other in a measurement direction X that intersects with the curvature direction Y of the glass sheet G (see FIG. 6 ) and runs along the main surface of the glass sheet G. This allows the measuring device 10 to measure the irregularities in the surface shape of the glass sheet G and determine its flatness. In this example, the measurement direction X, which intersects with the curvature direction Y of the glass sheet G and runs along the main surface of the glass sheet G, is a direction that intersects with both side edge portions Ga of the glass sheet G that is curved and supported by the jig 40. The measurement range in which the stylus 13 comes into contact with the glass sheet G to measure its flatness is a portion other than the contact points with the support member 43 and the locking pins 45 of the locking member 47.

[0034] In the case of the method for measuring the flatness of a glass sheet G according to the second embodiment, the radius of curvature of the glass sheet G to be curved when measuring the flatness of the glass sheet G is preferably 50 mm or more and 500 mm or less. Bending the glass sheet G with a radius of curvature of 50 mm or more can prevent damage to the glass sheet G due to excessive bending. Bending the glass sheet G with a radius of curvature of 500 mm or less allows for highly accurate measurements with good reproducibility. Note that the radius of curvature of the glass sheet G to be curved when measuring the flatness of the glass sheet G is preferably 100 mm or more and 350 mm or less.

[0035] As described above, according to the method for measuring the flatness of a glass sheet G according to the second embodiment, the glass sheet G is curved in an arc shape so as to be concave, and the glass sheet G and the stylus 13 in contact with the surface of the glass sheet G are moved relative to each other in a measurement direction X that intersects with the curvature direction Y and is along the main surface of the glass sheet G. Therefore, compared to a method in which the glass sheet G is placed on a surface plate and the flatness is measured, the flatness of the thin glass sheet G can be measured with high accuracy without being affected by the surface shape of the surface plate.

[0036] Therefore, the flatness of a glass plate G having a thickness of, for example, 0.5 mm or less, preferably 0.3 mm or less, which is easily affected by the surface shape of a surface plate when placed on the surface plate, can be measured with high precision. The lower limit of the thickness of the glass plate G is not particularly limited, but is, for example, 0.1 mm.

[0037] Furthermore, by using the jig 40, the glass plate G can be easily curved and positioned in a concave arc shape suitable for measurement, and the flatness of the thin glass plate G can be measured smoothly.

[0038] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0039] As described above, the present specification discloses the following: (1) A method for measuring the flatness of a glass plate, comprising: The glass plate is arranged so as to be curved in a convex or concave arc shape, A stylus of a measuring device is brought into contact with the surface of the glass plate, A method for measuring the flatness of a glass plate, comprising relatively moving the glass plate and the stylus in a direction that intersects with the curvature direction of the glass plate and is along the main surface of the glass plate. According to this method for measuring the flatness of a glass plate, the glass plate is bent into an arc shape so as to be convex or concave, and the flatness of the glass plate is measured by moving the glass plate and the stylus of a measuring device in contact with the surface of the glass plate relative to the glass plate in a direction that intersects the direction of the curvature and follows the main surface of the glass plate. This makes it possible to measure the flatness of particularly thin glass plates with high accuracy without being affected by the surface shape of the surface plate, as compared with methods that measure flatness by placing the glass plate on a surface plate.

[0040] (2) The method for measuring the flatness of a glass plate according to (1), wherein the glass plate is curved so that the radius of curvature is 50 mm or more and 500 mm or less. According to this method for measuring the flatness of a glass plate, the glass plate can be curved appropriately while preventing damage caused by bending the glass plate too much, and the flatness of a thin glass plate can be measured with high accuracy and high reproducibility.

[0041] (3) The method for measuring the flatness of a glass plate according to (1) or (2), wherein the glass plate has a thickness of 0.5 mm or less. According to this method for measuring the flatness of a glass plate, the flatness of a glass plate having a thickness of 0.5 mm or less, which is easily affected by the surface shape of a surface plate when placed on the surface plate, can be measured with high precision.

[0042] (4) A pair of support members each having a curved portion projecting in an arc shape are arranged at a distance from each other, The glass sheet is bridged over the support members by arranging both side edge portions of the glass sheet on the curved portions of the support members; The method for measuring the flatness of a glass plate according to any one of (1) to (3), wherein both side edge portions of the glass plate are fixed to the curved portions of the support member with clips, thereby curving the glass plate so as to be convex. According to this method for measuring the flatness of a glass plate, the glass plate can be easily curved and positioned in a convex arc shape suitable for measurement, and the flatness of a thin glass plate can be smoothly measured.

[0043] (5) A pair of support members having linear support portions are arranged at an interval; The glass sheet is bridged across the support members by placing both edge portions of the glass sheet on the support portions of the support members; The method for measuring the flatness of a glass plate according to any one of (1) to (3), wherein the glass plate is curved so as to be concave by engaging the locking pins of a locking member having a locking pin with both side edge portions of the glass plate and pulling down. According to this method for measuring the flatness of a glass plate, the glass plate can be easily curved into a concave arc suitable for measurement and positioned, and the flatness of a thin glass plate can be smoothly measured. [Explanation of symbols]

[0044] 10. Measuring equipment 13 Stylus 21 Curved section 23 Support member 25 clips 41 Support part 43 Support member 45 Locking pin 47 Locking member G Glass plate Ga lateral edge Gb Edge X measurement direction Y bending direction

Claims

1. A method for measuring the flatness of a glass plate, comprising: The glass plate is arranged so as to be curved in a convex or concave arc shape, A stylus of a measuring device is brought into contact with the surface of the glass plate, The glass plate and the stylus are moved relative to each other in a direction that intersects with the curvature direction of the glass plate and is along the main surface of the glass plate. Method for measuring the flatness of glass plates.

2. The glass plate is curved so that the radius of curvature is 50 mm or more and 500 mm or less. The method for measuring the flatness of a glass plate according to claim 1.

3. The glass plate has a thickness of 0.5 mm or less. The method for measuring the flatness of a glass plate according to claim 1.

4. A pair of support members each having a curved portion projecting in an arc shape are disposed at a distance from each other, The glass sheet is bridged over the support members by arranging both side edge portions of the glass sheet on the curved portions of the support members; The glass plate is curved convexly by fixing both side edge portions of the glass plate to the curved portions of the support member with clips. The method for measuring flatness of a glass plate according to any one of claims 1 to 3.

5. A pair of support members having linear support portions are arranged at a distance from each other, The glass sheet is bridged across the support members by placing both edge portions of the glass sheet on the support portions of the support members; a locking member having a locking pin, the locking pin being engaged with both side edge portions of the glass plate and pulled down, thereby curving the glass plate so as to be concave; The method for measuring flatness of a glass plate according to any one of claims 1 to 3.

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