Glass plate manufacturing method and manufacturing device

Abstract

A glass ribbon (G) is formed in a forming zone (11) and conveyed in a longitudinal direction by a conveying device (14), and the glass ribbon (G) is cut in a width direction by a cutting device (2) to cut out a glass plate (g). Then, the cut side end (Gt) of the glass ribbon (G) and the glass plate (g) are taken as measurement objects, the temperature of the measurement objects (Gt, g) is measured, and defects occurring in the measurement objects (Gt, g) are detected based on the measurement results of the measurement objects (Gt, g).

Description

Technical Field

[0001] The present invention relates to a technology for manufacturing a glass sheet, and more particularly to detecting a defect generated in a glass ribbon or a glass sheet after a glass ribbon is cut into glass sheets. Background Art

[0002] As a method for producing a glass sheet, a method using a down-draw method represented by an overflow down-draw method, a slot down-draw method, and a re-draw method is widely used.

[0003] In the manufacturing process of glass sheets using these methods, after continuously forming a glass ribbon, the glass ribbon is cut into predetermined lengths in the width direction to cut out glass sheets from the glass ribbon. At this time, defects may occur in the glass ribbon or the glass sheet.

[0004] Therefore, for example, Patent Document 1 discloses that a plurality of laser sensors are used to detect the presence of glass in a glass ribbon or glass plate after cutting, and based on the detection results, defects (breakage in this document) occurring in the glass ribbon or glass plate are automatically monitored. As the laser sensor here, a reflective sensor is used that irradiates a laser toward the glass ribbon or glass plate and detects reflected light reflected by the glass.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-104228 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, in the case of laser sensors, if the glass ribbon or glass plate shakes or vibrates on the conveying path, the state of the measured light such as the reflected light obtained from the laser irradiated toward the glass ribbon or glass plate is likely to change. As a result, there is a problem of erroneous detection of defects occurring in the glass ribbon or glass plate, and it is desired to detect these defects with higher accuracy.

[0010] From the above viewpoints, the present invention aims to detect defects occurring in the measurement objects with high accuracy by using the cut side edge of a glass ribbon after cutting, a glass sheet, or both the cut side edge of the glass ribbon and the glass sheet as measurement objects.

[0011] Solutions to Solve Problems

[0012] The first aspect of the present invention made to solve the above-mentioned problems is a method for manufacturing a glass plate, comprising: a forming step of forming a glass ribbon in a forming zone; a conveying step of conveying the glass ribbon along the length direction; and a cutting step of cutting the glass ribbon along the width direction to cut out a glass plate, wherein the method for manufacturing a glass plate comprises the following detection step: taking the cut side end of the glass ribbon cut in the cutting step, the glass plate, and any one of the cut side end of the glass ribbon and the glass plate as a measurement object, measuring the temperature of the measurement object, and detecting a defect generated in the measurement object based on the measurement result of the measurement object. Here, "defect" means a defect such as a defect (including an irregular shape) or breakage generated in the measurement object, and the measurement object itself that generates the defect is considered a defect (defective product) (hereinafter, the same).

[0013] According to this method, when the measuring object is the cut side end of the glass ribbon, the defect generated in the cut side end is detected, when the measuring object is the glass plate, the defect generated in the glass plate is detected, and when the measuring objects are both the cut side end of the glass ribbon and the glass plate, the defect generated in the cut side end and the glass plate is detected. When detecting the defect, the temperature of the measuring object does not show a large change even if the position of the measuring object changes due to swinging, vibration, etc. on the conveying path, but shows a large change in the part where the glass in the measuring object is missing or protruding. Therefore, according to this method, the defect generated in the measuring object can be detected with high accuracy.

[0014] In this method, in the cutting step, the glass ribbon may be broken along a score line extending in a width direction of the glass ribbon to cut out the glass sheet.

[0015] In this way, when the glass ribbon is broken and cut, the specific defects generated at the cut side end of the glass ribbon after cutting and the glass sheet can be detected with high accuracy. That is, in the cutting process, the glass ribbon can also be cut by laser cutting, laser melting, etc., but when the glass ribbon is broken and cut, the specific defects different from those in the case of other methods are generated. According to the structure here, such specific defects can be appropriately dealt with.

[0016] In the above method, in the forming step, the glass ribbon is formed by a down-draw method, and in the detection step, the temperature of the measurement object in a vertical position is measured as a temperature distribution measurement by a thermal imager. Here, the vertical position refers to a vertical position or a tilted position less than 45 degrees relative to the vertical direction (hereinafter the same).

[0017] In measuring the temperature distribution, a plurality of temperature sensors arranged along the width direction of a vertical glass ribbon or glass plate can be used. However, if a thermal imager is used, a highly precise temperature distribution can be obtained, and minute defects can be reliably detected.

[0018] In this method, the defect detected in the detecting step may include a shape defect of a cut surface on the upper side of the glass sheet cut in the cutting step.

[0019] The shape defect of the cut surface on the upper side of the glass plate is often caused by the consumption of the scribing blade or the cutter wheel, etc. If the shape defect is detected, appropriate measures such as replacement of the scribing blade or the cutter wheel can be implemented to prevent the shape defect from occurring on the cut surface on the upper side of the subsequent glass plate.

[0020] In this method, a distribution of height positions of the upper cut surface may be obtained based on a temperature distribution of the glass sheet, and a shape defect of the upper cut surface may be detected based on the height of the height positions.

[0021] In this way, by measuring the height based on the distribution of the height position in the cut surface on the upper side of the glass plate, it is possible to detect the shape defect of the cut surface, and the detection process can be rationalized. In this case, the space above the glass plate, that is, the boundary between the low temperature part and the high temperature part of the glass plate is depicted as the shape of the cut surface on the thermal image representing the temperature distribution of the thermal imager. And, if image analysis is performed based on the height of the boundary line, etc., the shape defect of the cut surface can be accurately detected.

[0022] In this method, when a shape defect of the upper cut surface is detected, the glass sheet may be discarded.

[0023] In this way, when a defective shape of the upper cut surface is detected, the glass plate can be discarded at an early stage, and contamination of a production line in a subsequent process can be prevented before it occurs.

[0024] In these methods, the defect detected in the detecting step may include a local breakage of the glass sheet cut in the cutting step.

[0025] Local breakage is likely to occur when, for example, the warpage of the glass ribbon is large. If local breakage is detected, appropriate measures such as reducing the warpage of the glass ribbon can be taken, and local breakage can be suppressed from occurring in subsequent glass sheets.

[0026] In this method, the area of ​​at least a part of the glass sheet may be obtained based on the temperature distribution of the glass sheet, and the local breakage may be detected based on the area and a first threshold value.

[0027] In this way, local damage is detected based on the area of ​​at least a part of the glass plate and the first threshold, so that accurate detection with little error can be achieved. In this case, in the thermal image representing the temperature distribution of the thermal imager, a low temperature depiction corresponding to local damage appears in a part of the part where a high temperature depiction should be performed due to the existence of the glass plate. In addition, the area of ​​only the high temperature part is obtained, and local damage is detected based on the area and the first threshold. The area of ​​the glass plate in this case is, for example, the area of ​​a part of the glass plate when the area that can be measured by the thermal imager is a part of the glass plate, and the area of ​​the entire area when the area that can be measured by the thermal imager is the entire area of ​​the glass plate. The area can be obtained by the number of pixels in the thermal image, etc. The first threshold here is set to, for example, 90% to 99% of the area of ​​the glass plate (the area corresponding to the above-mentioned area) when there is no defect at all. Therefore, when the area of ​​the high temperature part in the thermal image exceeds the first threshold, it is detected as no local damage, and when the area of ​​the high temperature part in the thermal image is less than the first threshold, it is detected as local damage.

[0028] In this method, when the local breakage is detected, the glass plate may be discarded.

[0029] In this way, the glass plate can be discarded at an early stage when a partial breakage is detected, thereby preventing contamination of a production line in a subsequent process.

[0030] In these methods, the defect detected in the detecting step may include crack breakage of the glass sheet associated with a vertical crack in the glass ribbon cut in the cutting step.

[0031] In this way, crack damage, which is different from the aforementioned shape defects and local damage, can be detected based on the thermal image of the thermal imager that shows the temperature distribution of the glass sheet. This crack damage is caused by the longitudinal crack of the cut glass ribbon. Here, the longitudinal crack means a crack formed in the up-down direction of the glass ribbon and the entire glass ribbon is damaged due to the passage of time. If this longitudinal crack occurs, a crack damage larger than the aforementioned local damage occurs in the glass sheet cut from the glass ribbon, so it is sometimes impossible to cut the glass sheet. According to the structure here, the occurrence of such longitudinal cracks in the glass ribbon can be detected based on the thermal image of the glass sheet instead of the glass ribbon.

[0032] In this method, the area of ​​at least a part of the glass sheet may be obtained based on the temperature distribution of the glass sheet, and the crack breakage may be detected based on the area and a second threshold value.

[0033] In this way, crack damage associated with the described longitudinal crack is detected based on the area of ​​the glass plate and the second threshold value, so that accurate detection with little error can be achieved. In this case, in the thermal image of the thermal imager representing the temperature distribution, a low temperature depiction corresponding to the crack damage appears in a part of the part that should be depicted at a high temperature due to the existence of the glass plate. It should be noted that crack damage also includes damage in which the glass plate becomes non-existent. In this case, the high temperature part indicating the existence of the glass plate disappears on the thermal image. In this case, the area of ​​the high temperature part is calculated (it may also be zero), and the crack damage is detected based on the area and the second threshold value. The area of ​​the glass plate in this case is also the same as the case described above, for example, the area of ​​a part of the glass plate or the entire area, and can be calculated by the number of pixels in the thermal image, etc. The second threshold value here is set to, for example, 30% to 50% of the area of ​​the glass plate (the area corresponding to the above-mentioned area) when there is no defect at all. Therefore, when the area of ​​the high temperature part in the thermal image exceeds the second threshold, it is detected as no crack damage, and when the area of ​​the high temperature part in the thermal image is below the second threshold, it is detected as crack damage. It should be noted that the second threshold is a value smaller than the first threshold already described, so the local damage already described is detected as defective when it is below the first threshold and exceeds the second threshold.

[0034] In this method, when the crack breakage is detected, it may be regarded that a vertical crack of the glass ribbon has occurred, and a cutting device used for executing the cutting step may be retracted.

[0035] In this way, when crack breakage of the glass plate is detected, it is considered that a longitudinal crack has occurred in the glass ribbon, so appropriate countermeasures can be taken for the longitudinal crack. In detail, as described above, the crack of the glass plate is generated along with the longitudinal crack of the broken glass ribbon. Therefore, if crack breakage of the glass plate is detected, the longitudinal crack of the glass ribbon is also detected. That is, the generation of crack breakage of the glass plate is considered to be the generation of the longitudinal crack of the glass ribbon. The conditions that serve as the basis for judging whether it is crack breakage (for example, the second threshold value described above) are set to the conditions that satisfy this phenomenon. From this point of view, according to the structure here, when crack breakage of the glass plate is detected, that is, when a longitudinal crack of the glass ribbon is considered to have occurred, the cutting device can be retreated as soon as possible. In this way, the contamination and failure of the cutting device caused by a large amount of glass pieces and glass powder flying and falling from the glass ribbon due to the generation of longitudinal cracks can be prevented in advance.

[0036] In these methods, the thermal imager may measure the temperature distribution of the measurement object from obliquely below.

[0037] Thus, when the area measurable by the thermal imager is a part of the area of ​​the measuring object (for example, if the measuring object is a glass plate, it is a part of the area in the vertical direction of the glass plate), the following advantages are obtained. That is, when the measurement is performed by the thermal imager from obliquely below, the area where the measuring object can be measured is longer in the vertical direction than the area where the measurement is performed along the horizontal direction. Therefore, the advantage of being able to detect the generated defect through a wider measurement area is obtained. In addition, the following advantages are also obtained. That is, when the measurement is performed by the thermal imager along the horizontal direction or when the measurement is performed by the thermal imager from obliquely above, it is necessary to set the thermal imager at a relatively high position compared with the case where the measurement is performed from obliquely below. In such a case, the peripheral devices (such as the device for forming the scribe line, etc.) arranged around the cutting position of the glass ribbon may interfere with the thermal imager, and the degree of freedom of the installation space of the thermal imager is reduced. According to the structure here, compared with the above-mentioned case of measuring from the horizontal direction and obliquely above, the thermal imager can be set at a relatively low position. Therefore, the thermal imager is unlikely to interfere with the above-mentioned peripheral devices, and the degree of freedom of the installation space of the thermal imager is high.

[0038] In these methods, the thermal imager may be capable of adjusting a direction directed toward the surface of the measurement object in a vertical direction.

[0039] In this way, it is possible to appropriately deal with the disadvantages that may be caused when the size, thickness, type, etc. of the glass ribbon formed and conveyed is changed, or when the measuring object is swung even without such a change. That is, when such a change or swung occurs, the position of the measuring object may be offset in the vertical direction after cutting. If such a position offset occurs, not only the detection accuracy of the defect generated in the measuring object is reduced, but also, depending on the situation, part or all of the measuring object may be separated from the area that can be measured by the thermal imager in the vertical direction, making it impossible to detect the defect. According to the structure here, the direction of the thermal imager can be adjusted in the vertical direction (the direction pointing to the surface of the measuring object), so that the area that can be measured by the thermal imager can be offset corresponding to the vertical deviation of the measuring object. In this way, the area where the measuring object can be measured is appropriately corrected, and the detection of defects is further improved in accuracy.

[0040] In these methods, the thermal imager may be capable of adjusting a direction directed toward the surface of the measurement object in a width direction.

[0041] In this way, even if the size, thickness, type, etc. of the glass ribbon is changed or the measuring object is swung so that the cut measuring object is shifted in the width direction, the direction of the thermal imager is adjusted in the width direction, thereby appropriately correcting the area where the measuring object can be measured.

[0042] In these methods, the thermal imager may be capable of adjusting a position in a vertical direction.

[0043] In this way, even if the size, thickness, type, etc. of the glass ribbon is changed or the measuring object is swung and the measuring object after being cut is shifted in the vertical direction, the area where the measuring object can be measured can be appropriately corrected by adjusting the vertical position of the thermal imager. In this case, the area where the measuring object can be measured can be shifted in the vertical direction without changing the direction of the thermal imager or while changing the direction of the thermal imager.

[0044] In these methods, it is also possible that, on a thermal image obtained by measuring the temperature distribution using the thermal imager, the height position of the upper edge of the cut glass plate is detected, the detected height position is used as the origin position in the up and down directions, a defect inspection area is set with the upper end portion of the glass plate and the space above the upper end portion as the objects, and defects generated in the glass plate are detected by image analysis in the defect inspection area.

[0045] In this way, the defect inspection area is set at an appropriate position on the thermal image of the thermal imager, so that the defects generated in the glass plate can be further detected with high precision. In detail, the position of the glass plate depicted in the thermal image in the up-down direction is inconsistently determined. The reason is not only caused by the changes and swings as described above, but also caused by the timing of the thermal imager acquiring the thermal image each time the measurement is performed. In this case, when the defect inspection area is set on the thermal image, deviations and errors occur in the up-down position of the defect inspection area, which may cause erroneous detection of defects generated in the glass plate. According to the structure here, the height position of the upper edge of the glass plate depicted in the thermal image is detected, and the detected height position is used as the origin position in the up-down direction to set the defect inspection area, so the position of the defect inspection area for the glass plate on the thermal image in the up-down direction is consistently determined. As a result, it is not easy to produce erroneous detection when the defects generated in the glass plate are detected by image analysis in the defect inspection area, and the detection accuracy of the defects can be further reliably improved.

[0046] A second aspect of the present invention made to solve the above-mentioned problems is a glass plate manufacturing device, comprising: a forming area that forms a glass ribbon; a conveying device that conveys the glass ribbon along the length direction; and a cutting device that cuts the glass ribbon along the width direction to cut out a glass plate. The glass plate manufacturing device is characterized in that the glass plate manufacturing device is provided with a detection device, which takes the cut side end of the glass ribbon cut by the cutting device, the glass plate, and any one of the cut side end of the glass ribbon and the glass plate as a measurement object, measures the temperature of the measurement object, and detects a defect generated in the measurement object based on the measurement result of the measurement object.

[0047] According to this embodiment, it is possible to obtain the same effects as those of the above-described manufacturing method having substantially the same configuration as the manufacturing apparatus.

[0048] Effects of the Invention

[0049] According to the present invention, any one of the cut side edge of the cut glass ribbon, the glass sheet, or both the cut side edge of the glass ribbon and the glass sheet can be measured, and defects occurring in the measured object can be detected with high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a longitudinal sectional side view which shows the whole structure of the glass plate manufacturing apparatus which concerns on embodiment of this invention.

[0051] Figure 2 It is shown from Figure 1 A schematic front view of the main parts of the glass plate manufacturing device when viewed in the A direction.

[0052] Figure 3 This is a front view showing a schematic state immediately after a glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0053] Figure 4a This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0054] Figure 4b This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0055] Figure 5a This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0056] Figure 5bThis is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0057] Figure 6 This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0058] Figure 7 This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0059] Figure 8 This is a front view showing exaggeratedly the state of the cut-side end portion of the glass ribbon and the glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0060] Fig. 9 This is a schematic front view for explaining a first example of a method for detecting defects of a glass sheet and a glass ribbon based on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0061] Fig.10 This is a schematic front view for explaining a second example of a method for detecting defects of a glass sheet and a glass ribbon based on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0062] Fig.11 This is a front view showing a third example of a method for detecting defects of a glass sheet and a glass ribbon based on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0063] Fig.12 This is a schematic front view for explaining another method of the first example of detecting defects of a glass sheet and a glass ribbon based on a thermal image of temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0064] Fig.13 This is a schematic front view for explaining another method of the second example of detecting defects of a glass sheet and a glass ribbon based on a thermal image of temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0065] Fig.14This is a schematic front view for explaining another method of the third example of detecting defects of a glass sheet and a glass ribbon based on a thermal image of temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0066] Fig.15 This is a front view showing a fourth example of a method for detecting defects of a glass sheet and a glass ribbon based on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0067] Fig.16 It is a front view showing a fifth example of a method for detecting defects of a glass sheet and a glass ribbon based on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0068] Fig.17 A glass sheet manufacturing device according to a modified example of an embodiment of the present invention is provided. Figure 1 A schematic front view of the manufacturing device when viewed from the A direction.

[0069] Fig.18 This is a schematic front view showing a range that can be measured by a thermal imager as a component of a glass sheet manufacturing apparatus according to a modified example of the embodiment of the present invention.

[0070] Fig.19 This is a schematic side view showing the relationship between a thermal imager and a glass sheet as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0071] Fig. 20 This is a schematic side view showing a range in which a glass sheet can be measured by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0072] Fig.21 This is a schematic side view showing the relationship between a thermal imager and a glass sheet as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0073] Fig. 22 This is a schematic plan view showing the relationship between a thermal imager and a glass sheet as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0074] Fig.23 This is a schematic side view showing the relationship between a thermal imager and a glass sheet as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0075] Fig.24This is a front view showing a method for setting a defect inspection area on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0076] Fig.25 This is a front view showing a method for setting a defect inspection area on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0077] Fig.26 This is a front view showing a first example of a method of detecting defects by image analysis in a defect inspection area set on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention.

[0078] Fig. 27 This is a front view showing a second example of a method of detecting defects by using image analysis in a defect inspection area set on a thermal image of a temperature distribution obtained by a thermal imager as a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION

[0079] Hereinafter, one embodiment of the present invention will be described based on the drawings.

[0080] Figure 1 1 is a longitudinal sectional side view showing the overall structure of the glass plate manufacturing apparatus of the present embodiment. As shown in the figure, the glass plate manufacturing apparatus includes a processing apparatus 1 for a glass ribbon G, a cutting apparatus 2, and a detection apparatus 3.

[0081] The processing device 1 comprises: a forming zone 11, which continuously forms a glass ribbon G; a heat treatment zone 12, which performs heat treatment (annealing) on ​​the glass ribbon G; a cooling zone 13, which cools the glass ribbon G to near room temperature; and a conveying device 14, which includes roller pairs R arranged in multiple sections above and below the forming zone 11, the heat treatment zone 12 and the cooling zone 13.

[0082] The forming zone 11 and the heat treatment zone 12 are composed of a furnace in which a conveying path of the glass ribbon G is surrounded by a wall, and heating devices such as heaters for adjusting the temperature of the glass ribbon G are arranged at appropriate positions in the furnace. On the other hand, in the cooling zone 13, the conveying path of the glass ribbon G is not surrounded by a wall, but is open to the external environment at room temperature, and no heating devices such as heaters are arranged.

[0083] A forming body 15 for forming a glass ribbon G from molten glass Gm by an overflow down-draw method is arranged in the inner space of the forming area 11. The molten glass Gm supplied to the forming body 15 overflows from a groove (not shown) formed at a top 15a of the forming body 15. The overflowing molten glass Gm flows along two side surfaces 15b of the forming body 15 having a wedge-shaped cross section and merges at the lower end. Thus, a plate-shaped glass ribbon G is continuously formed. The continuously formed glass ribbon G is fed downward in a vertical posture (preferably a vertical posture).

[0084] The internal space of the heat treatment zone 12 has a predetermined temperature gradient as it moves downward. The glass ribbon G in a vertical position is heat treated (annealed) in such a manner that the temperature decreases as it moves downward in the internal space of the heat treatment zone 12. The internal strain of the glass ribbon G is reduced by the heat treatment. The temperature gradient of the internal space of the heat treatment zone 12 is adjusted by, for example, a heating device provided on the inner surface of the wall of the heat treatment zone 12.

[0085] The plurality of roller pairs R constituting the conveying device 14 clamps both ends of the glass ribbon G in the longitudinal position in the width direction from both sides. The roller pair R disposed at the uppermost portion of the forming zone 11 is a cooling roller. It should be noted that, in the internal space of the heat treatment zone 12, the plurality of roller pairs R may include roller pairs that do not clamp the side ends of the glass ribbon G. That is, the opposing interval of the roller pairs R may be made larger than the thickness of both ends of the glass ribbon G in the width direction, and the glass ribbon G may be passed between the roller pairs R.

[0086] In the present embodiment, both widthwise end portions of the glass ribbon G manufactured by the processing apparatus 1 have portions (hereinafter also referred to as “ear portions”) thicker than the widthwise central portion due to shrinkage during the forming process.

[0087] The cutting device 2 is configured to cut the vertical glass ribbon G in the width direction according to a predetermined length below the processing device 1, thereby sequentially cutting out glass sheets from the glass ribbon G. The glass sheet is removed from the edge portion in a subsequent process to become a glass original sheet (mother glass sheet) from which one or more product glass sheets are collected. Here, the width direction is a direction perpendicular to the length direction (conveying direction) of the glass ribbon G, and is substantially consistent with the horizontal direction in the present embodiment.

[0088] like Figure 1 as well as Figure 2 As shown, the cutting device 2 includes a scored line forming device 21 and a breaking device 22 .

[0089] The scoring line forming device 21 is a device for forming a scoring line S on the first main surface of the glass ribbon G in a longitudinal position descending from the processing device 1 at the scoring line forming position P1. In the present embodiment, the scoring line forming device 21 includes: a cutter wheel 23, which forms the scoring line S on the first main surface of the glass ribbon G along its width direction; and a supporting member 24 (for example, a supporting rod, a supporting roller) which supports the second main surface (the surface on the opposite side of the first main surface) of the glass ribbon G at a position corresponding to the cutter wheel 23.

[0090] The cutter wheel 23 and the supporting member 24 are structured to follow the descending glass ribbon G and form the score lines S in the entire region or part of the width direction of the glass ribbon G. In the present embodiment, the score lines S are also formed in the ear portions having a relatively large thickness. It should be noted that the score lines S may also be formed by irradiation of laser or the like.

[0091] The breaking device 22 is a device for breaking the glass ribbon G along the score line S at a breaking position (cutting position) P2 set below the score line forming position P1 to cut out a glass sheet. In the present embodiment, the breaking device 22 includes: a breaking member 25 that contacts the area where the score line S is formed from the second main surface side; and a holding mechanism 26 that holds the lower area of ​​the glass ribbon G at a position lower than the breaking position P2.

[0092] The breaking member 25 is composed of a plate-like body (platform) having a flat surface that follows the descending glass ribbon G and contacts the entire region or part of the width direction of the glass ribbon G. The contact surface of the breaking member 25 may be a curved surface that curves in the width direction.

[0093] The holding mechanism 26 includes: a chuck 27 disposed at a plurality of locations in the vertical direction at both ends of the glass ribbon G in the width direction; and an arm 28 (see Figure 2 ), which holds the above-mentioned multiple chucks 27 at both ends in the width direction. These arms 28 are used to make the multiple chucks 27 follow the glass ribbon G that is being lowered, and to bend the glass ribbon G using the breaking member 25 as a fulcrum (action in the B direction). As a result, bending stress is applied to the score line S and its vicinity, and the glass ribbon G is broken in the width direction along the score line S. As a result of the cutting based on the breaking, a glass sheet is cut out from the glass ribbon G. It should be noted that the chucks 27 can also be changed to other holding methods such as holding the glass ribbon G by negative pressure adsorption.

[0094] like Figure 1 as well as Figure 3As shown in FIG. 1 , the detection device 3 is a device for measuring the cut side end Gt of the glass ribbon G and the glass plate g cut by the cutting device 2 and detecting defects generated in the measuring objects g and Gt. In this embodiment, the detection device 3 includes a thermal imager 31, a detection unit 32, a control unit 33, and an alarm unit 34. Here, the glass ribbon G and the glass plate g have a width direction length of 1000 to 3500 mm and a thickness of 100 to 2000 μm. In addition, the longitudinal length (vertical length) of the glass plate g is 800 to 3000 mm.

[0095] The thermal imager 31 is a device for measuring the temperature distribution of the measuring object Gt, g, and is arranged at a position lower than the height position of the cutter wheel 23 and higher than the lower end of the holding mechanism 26. The thermal imager 31 of this embodiment is arranged at a position lower than the height position of the breaking member 25 and higher than the lower end of the holding mechanism 26. In addition, the thermal imager 31 is arranged at a position in the width direction center of the measuring object Gt, g on one main surface side (the first main surface side of the glass ribbon G) of the measuring object Gt, g in a manner separated from the main surface. The separation distance between the thermal imager 31 and the measuring object Gt, g can be arbitrarily set within a range in which the temperature distribution of the measuring object Gt, g can be measured non-contact (for example, a range of 800 to 3000 mm). It should be noted that the thermal imager 31 may also be arranged on the other main surface side of the measuring object Gt, g.

[0096] The detection unit 32 performs image analysis on the thermal image showing the temperature distribution obtained by the thermal imager 31, and detects the defects generated in the measurement objects g and Gt based on the results. The detection unit 32 is composed of, for example, a personal computer. Here, when the glass ribbon G is cut by breaking, not only the glass ribbon G after cutting, but also the glass plate g is swung due to the vibration, swing, etc. of the holding mechanism 26. In addition, when the thickness of the glass ribbon G is thin or the glass ribbon G is warped, the swing of the glass ribbon G and the glass plate g after cutting may become significant. However, since the detection unit 32 detects the defects generated in the measurement objects g and Gt based on the temperature distribution obtained by the thermal imager 31, it is not easily affected by the negative effects of the swing of the glass ribbon G and the glass plate g.

[0097] When a defect is detected by the detection unit 32 , the control unit 33 issues a control signal for performing a gripping operation and a releasing operation of the chuck 27 of the gripping mechanism 26 , a retreat movement, and a return movement of the cutting device 2 , and the like.

[0098] The alarm unit 34 issues an alarm when a specific defect (for example, a crack breakage g4 of the glass sheet g accompanying a longitudinal crack G4 of the glass ribbon G described later) is detected by the detection unit 32. The alarm is notified to the operator through voice, display, etc. It should be noted that the alarm unit 34 may be omitted.

[0099] Figure 4a to Figure 8 The following are examples of defects that can be detected by the detection unit 32. In addition, in the above-mentioned drawings, the holding mechanism 26 and the like are omitted for convenience.

[0100] Figure 4a The glass sheet g shown in the figure has a shape defect caused by a protrusion (generally referred to as) g1 protruding upward from the middle part in the width direction on the upper cut surface ga. The protrusion g1 is, for example, several mm in height and several mm in width. As a result, a shape defect caused by a notch G2 recessed upward from the middle part in the width direction on the lower cut surface Ga of the glass ribbon G shown in the figure. On the contrary, Figure 4b The glass sheet g shown in the figure has a shape defect caused by a notch g2 that is recessed downward from the middle portion in the width direction on the upper cut surface ga. The notch g2 is, for example, several mm in depth and several mm in width. As a result, the shape defect caused by a protrusion G1 that protrudes downward from the middle portion in the width direction on the lower cut surface Ga of the glass ribbon G shown in the figure.

[0101] Figure 5a The glass sheet g shown in the figure has a shape defect caused by a protrusion g1 protruding upward from one end in the width direction on the upper cut surface ga. The protrusion g1 is, for example, several mm in height and several mm in width. As a result, the glass ribbon G shown in the figure has a shape defect caused by a notch G2 missing from one end in the width direction on the lower cut surface Ga. Such shape defects on the cut surfaces ga and Ga are caused by the relatively thick wall of the ear. On the contrary, Figure 5b The glass sheet g shown in the figure has a shape defect caused by a notch g2 missing from one end in the width direction on the upper cut surface ga. As a result, a shape defect caused by a protrusion G1 protruding downward from one end in the width direction on the lower cut surface Ga of the glass ribbon G shown in the figure. Such shape defects of the cut surfaces ga and Ga are also caused by the relatively thick wall of the ear portion.

[0102] Figure 6The glass sheet g shown in the figure has a wavy shape defect on the entire upper cut surface ga. As a result, the entire lower cut surface Ga of the glass ribbon G shown in the figure also has a wavy shape defect. This shape defect is caused by the crack deviating from the score line. In addition, the shape defect caused by the crack deviating from the score line may be a case where a part of the cut surface ga is wavy, or a part or the entire cut surface ga is bow-shaped.

[0103] It should be noted that in Figure 4a to Figure 6 In the example shown, the irregularities of the shape defects in the glass sheet g and the irregularities of the shape defects in the glass ribbon G are located at the same position in the width direction and have an opposite relationship, but this relationship is not necessarily required.

[0104] Figure 7 The glass sheet g shown has a local break g3 starting from the upper cut surface ga. The local break g3 has a depth of 3 to 500 mm and a width of 10 to 2000 mm, for example, and is larger than the above-mentioned gap g2. The number of the local break g3 may be multiple. The local break g3 is caused by the breakage of a part of the glass sheet g (the periphery of the upper cut surface ga and the middle part in the width direction) accompanying the cutting.

[0105] Figure 8 The glass sheet g shown has crack damage g4 accompanying the vertical crack G4 of the glass ribbon G at one location. The crack damage g4 is caused by the vertical crack G4 of the glass ribbon G accompanying the crack progressing in the up-down direction. The vertical crack G4 may cause the entire glass ribbon G to be damaged as time passes. Therefore, the crack damage g4 of the glass sheet g accompanying the vertical crack G4 of the glass ribbon G may tend to become larger in subsequent glass sheets g, and may eventually make it impossible to cut the glass sheet g from the glass ribbon G.

[0106] Figures 9 to 16 1 and 2 are thermal images F1 to F5 showing the temperature distribution measured by the thermal imager 31. The thermal images F1 to F5 reflect the measurement objects g and Gt having defects. Figures 9 to 14 For convenience, only the main part of the measured thermal image is shown. Here, the temperature of the measurement objects g and Gt is, for example, less than 100°C, preferably less than 80°C. In addition, the temperature of the measurement objects g and Gt is higher than the temperature of the surrounding space region Z. Therefore, in the thermal images F1 to F5, the glass plate g and the glass ribbon G are depicted in bright colors, and the surrounding space region Z is depicted in dark colors.

[0107] exist Figures 9 to 11The thermal images F1 to F3 shown reflect the shapes of the cut surfaces ga and Ga of the measurement objects g and G. The detection unit 32 obtains the distribution of the height positions of the cut surfaces ga and Ga based on these thermal images F1 to F3, and detects whether a shape defect occurs on the cut surfaces ga and Ga based on the height (here, the height difference) of the height positions. The specific method is described below.

[0108] exist Fig. 9 The thermal image F1 shown reflects the described Figure 4a Defective measuring objects g, Gt in the manner shown. Here, a method for the detection unit 32 to detect the shape defect caused by the protrusion g1 generated on the cut surface ga on the upper side of the glass plate g based on the thermal image F1 is described. First, in the area (relatively bright area) where the glass plate g is drawn on the thermal image F1, a straight line K1 that serves as a basis and is parallel to the straight line K0 is set at a position separated by a predetermined distance from the straight line K0 forming the scribed line S. Next, the maximum and minimum values ​​of the distance from the straight line K1 to the contour line on the upper side of the area where the glass plate g is drawn are calculated. In the example, the distance (maximum value) Ma from the straight line K1 to the top gx of the protrusion g1 and the distance (minimum value) Mi from the straight line K1 to the straight line K0 are calculated. Then, the difference ΔM between the maximum value Ma and the minimum value Mi is calculated, and based on the difference ΔM and the threshold value, the detection unit 32 detects the shape defect generated on the cut surface ga on the upper side of the glass plate g. Specifically, the detection unit 32 detects that there is no shape defect when the difference ΔM is less than the threshold value, and detects that there is a shape defect when the difference ΔM exceeds the threshold value. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that the glass sheet g has a shape defect. Figure 5a In the case where the protrusion g1 is generated on the upper cut surface ga of the glass plate g as shown, the detection unit 32 detects whether or not a shape defect has occurred in the glass plate g by the same method as described here.

[0109] exist Fig.10 The thermal image F2 shown reflects the described Figure 4bDefective measuring objects g, Gt in the manner shown. Here, a method for the detection unit 32 to detect shape defects caused by the notch g2 generated on the cut surface ga on the upper side of the glass plate g based on the thermal image F2 is described. Regarding the thermal image F2, a straight line K1 is also set at the same position as above, and the maximum and minimum values ​​of the distance from the straight line K1 to the upper contour line of the area where the glass plate g is drawn are calculated. In the example, the distance (minimum value) Mi from the straight line K1 to the lowest part gy of the notch g2 and the distance (maximum value) Ma from the straight line K1 to the straight line K0 are calculated. And, the detection unit 32 detects that there is no shape defect when the difference ΔM between the maximum value Ma and the minimum value Mi is below the threshold, and detects that there is a shape defect when the difference ΔM exceeds the threshold. Here, because the difference ΔM exceeds the threshold, the detection unit 32 detects that a shape defect has occurred on the glass plate g. It should be noted that, in the case of Figure 5b In the case where a notch g2 is generated on the upper cut surface ga of the glass plate g in the manner shown, the detection unit 32 detects whether or not the notch g2 is a shape defect by the same method as described here.

[0110] exist Fig.11 The thermal image F3 shown reflects the described Figure 6 Defective measuring objects g, Gt in the manner shown. Here, a method for the detection unit 32 to detect shape defects caused by the wave shape generated on the cut surface ga on the upper side of the glass plate g based on the thermal image F3 is described. Regarding the thermal image F3, a straight line K1 is set at the same position as above, and the maximum and minimum values ​​of the distance from the straight line K1 to the upper contour line of the area where the glass plate g is drawn are calculated. In the example, the distance (maximum value) Ma from the straight line K1 to the top gz of the highest peak among multiple peaks and the distance (minimum value) Mi from the straight line K1 to the lowest part gZ of the lowest valley among multiple valleys are calculated. Then, the detection unit 32 detects that there is no shape defect when the difference ΔM between the maximum value Ma and the minimum value Mi is less than the threshold value, and detects that there is a shape defect when the difference ΔM exceeds the threshold value. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that a shape defect has occurred in the glass plate g.

[0111] It should be noted that Fig. 9 The shape defect caused by the notch G2 generated on the cut surface Ga at the lower side of the glass ribbon G in the thermal image F1 shown can be corrected by comparing the thermal image F1 with the thermal image G2 of the glass ribbon G shown in FIG. Fig.10 The shape defect caused by the notch g2 on the thermal image F2 shown in the figure is detected in substantially the same manner. Fig.10 The shape defect caused by the protrusion G1 generated on the cut surface Ga on the lower side of the glass ribbon G in the thermal image F2 shown can be corrected by comparing the thermal image F2 with the thermal image F2 of FIG. Fig. 9The shape defect caused by the protrusion g1 on the thermal image F1 shown in the figure is detected in substantially the same manner. Fig.11 The shape defect caused by the wave shape generated on the cut surface Ga on the lower side of the glass ribbon G in the thermal image F3 shown can be detected by substantially the same method as the detection of the shape defect caused by the wave shape of the glass sheet g on the thermal image F3 shown in the figure. It should be noted that the substantially same method mentioned here means that only the upper and lower relationships are reversed and the method itself is the same.

[0112] In this case, the detection unit 32 Figures 9 to 11 When the thermal images F1 to F3 shown in the example detect that the glass plate g has a shape defect, the gripping action of the chuck 27 of the gripping mechanism 26 is released based on the control signal from the control unit 33, so that the glass plate g is discarded. The discarded glass plate g is recovered. Here, the glass plate g after cutting is often gripped at the upper part and transported to the subsequent process. Therefore, if the glass plate g with a shape defect on the upper cut surface ga is discarded in advance, the breakage of the glass plate g when gripping the upper part and transporting it and the contamination of the production line associated with it can be prevented in advance. In addition, the shape defect on the upper cut surface ga of the glass plate g is easily caused by the consumption of the cutter wheel 23, so when the detection unit 32 detects that the shape defect has occurred, it is preferred to replace the cutter wheel 23. In this way, the shape defect in the subsequent glass plate g can be suppressed.

[0113] It should be noted that in Figures 9 to 11 In the method shown, the maximum value Ma, the minimum value Mi, and the difference ΔM are obtained based on the straight lines K0 and K1, but the maximum value Ma, the minimum value Mi, and the difference ΔM may be obtained without using the straight lines K0 and K1. Specifically, the contour line of the upper side of the glass plate g may be obtained from the thermal image, the height of the point with the largest height position in the contour line may be taken as the maximum value Ma, and the height of the point with the smallest height position in the contour line may be taken as the minimum value Mi, and the difference ΔM may be obtained from these values.

[0114] Figure 12 to Figure 14 The above examples are respectively given Figures 9 to 11 The thermal images F1 to F3 shown are other methods for detecting shape defects of the glass plate g. In these other methods, the detection unit 32 also obtains the distribution of the height positions of the cut surfaces ga and Ga from the thermal images F1 to F3, and detects shape defects of the cut surfaces ga and Ga based on the heights.

[0115] exist Fig.12In the illustrated method, first, on the thermal image F1, the line L0, which is the regular cutting line of the glass plate g, i.e., the scribing line S, is used as a reference, and measurement lines L1 and L2 are drawn to the upper and lower sides thereof. The two measurement lines L1 and L2 are parallel to the line L0 and are separated from the line L0 by the same distance. In addition, it is measured whether there is a portion with a brightness higher than a preset set value, that is, whether there is a portion with a temperature higher than a preset set temperature, on the upper measurement line L1. In addition, it is measured whether there is a portion with a brightness higher than a preset set value (whether there is a portion with a temperature higher than a preset set value) on the lower measurement line L2. In this case, the range of measuring brightness (temperature) is the range of the entire area in the width direction of the glass plate g on the measurement lines L1 and L2. In this thermal image F1, there is a portion with a brightness (temperature) higher than the set value on the upper measurement line L1, and the brightness (temperature) is higher than the set value in the entire area on the lower measurement line L2. The detection unit 32 detects that a shape defect has occurred in the glass sheet g by recognizing this state. Figure 5a The protrusion g1 generated on the cut surface ga on the upper side of the glass plate g in the manner shown is also detected by the detection unit 32 as to whether it is a shape defect by the same method as described here.

[0116] Fig.13 The illustrated method is also similar to the case already described, using line L0 as a reference on the thermal image F2, and drawing measurement lines L1 and L2 to the upper and lower sides thereof, and measuring the brightness (temperature) on the upper measurement line L1 and the brightness (temperature) on the lower measurement line L2. In the thermal image F2, the brightness (temperature) is lower than the set value in the entire area on the upper measurement line L1, and there is a portion on the lower measurement line L2 where the brightness (temperature) is lower than the set value. The detection unit 32 detects that a shape defect has occurred in the glass plate g by recognizing this state. It should be noted that, regarding the case already described, Figure 5b The notch g2 generated on the cut surface ga on the upper side of the glass plate g in the manner shown is also detected by the detection unit 32 as to whether or not it is a shape defect by the same method as described here.

[0117] Fig.14 The illustrated method is also similar to the above-described case, with line L0 as the reference, and measuring lines L1 and L2 are drawn on the upper and lower sides of the thermal image F3, and the brightness (temperature) on the upper measurement line L1 and the brightness (temperature) on the lower measurement line L2 are measured. In the thermal image F3, there are multiple (two in the example) portions on the upper measurement line L1 where the brightness (temperature) is higher than the set value, and the brightness (temperature) is higher than the set value in the entire area on the lower measurement line L2. The detection unit 32 detects that a shape defect has occurred in the glass plate g by recognizing this state.

[0118] Fig.15 as well as Fig.16 The thermal images F4 and F5 reflecting the entire area of ​​the glass sheet g and the cut side end Gt of the glass ribbon G are shown. Based on these thermal images F4 and F5, the detection unit 32 obtains the area of ​​the measurement objects g and Gt, and detects defects generated in the measurement objects g and G based on the area and the threshold value. The specific method is described below.

[0119] exist Fig.15 The thermal image F4 shown reflects the described Figure 7 The defective measuring objects g, Gt in the manner shown. Here, the method for the detection unit 32 to detect the local breakage g3 generated in the glass plate g based on the thermal image F4 is described. First, the area of ​​the glass plate g is obtained based on the number of pixels on the thermal image F4. In this case, the area of ​​the glass plate g held by the chuck 27 may be lower in temperature than the area not held, and may be depicted in a dark color to the same extent as the space area Z. In this case, the area of ​​the area where the main surface of the glass plate g is exposed is obtained. It should be noted that when the area of ​​the glass plate g held by the chuck 27 and the area not held are at the same temperature and both are depicted in a light color, the area of ​​the entire area of ​​the glass plate g is obtained. When the area exceeds a first threshold, the detection unit 32 detects that there is no local breakage g3, and when the area is less than the first threshold and exceeds a second threshold described later, the detection unit 32 detects that there is a local breakage g3. The first threshold is, for example, 90% to 99% of the area of ​​the glass plate g in a state where no defect occurs (the area corresponding to the above-mentioned area). Here, since the above-mentioned area is equal to or smaller than the first threshold value and exceeds the second threshold value, the detection unit 32 detects that a local break g3 has occurred in the glass plate g.

[0120] In this case, the detection unit 32 Fig.15 When the illustrated thermal image F4 detects that a local break g3 has occurred on the glass sheet g, the gripping action of the clamp 27 of the gripping mechanism 26 is released based on a control signal from the control unit 33, and the glass sheet g is discarded. The discarded glass sheet g is recovered. As a result, it is less likely that the glass sheet g with the local break g3 is mistakenly transported to a subsequent process and subjected to subsequent processing. In addition, the local break g3 of the glass sheet g is likely to occur when the warp of the glass ribbon G is large. Therefore, when the detection unit 32 detects that the local break g3 has occurred, it is preferable to implement measures to reduce the warp of the glass ribbon G, so that the local break g3 can be suppressed from occurring in the subsequent glass sheet g.

[0121] exist Fig.16 The thermal image F5 shown reflects the described Figure 8The defective measuring objects g and Gt in the manner shown are described. Here, the method by which the detection unit 32 detects the crack damage g4 associated with the vertical crack G4 of the glass ribbon G based on the thermal image F5 is described. First, the area of ​​the glass plate g is obtained based on the number of pixels on the thermal image F5. The relationship between the area of ​​the glass plate g and the chuck 27 is the same as that described above. When the area exceeds the second threshold, the detection unit 32 detects that there is no crack damage g4, and when the area is less than the second threshold, the detection unit 32 detects that there is crack damage g4. The second threshold is, for example, 30% to 50% of the area of ​​the glass plate g in a state where no defect occurs (the area corresponding to the above-mentioned area). Here, since the above-mentioned area is less than the second threshold, the detection unit 32 detects that the crack damage g4 has occurred in the glass plate g. In this case, the crack damage g4 of the glass plate g is damage associated with the vertical crack G4 of the glass ribbon G as described above. Therefore, when the detection unit 32 detects the occurrence of the crack g4 in the glass sheet g, it also detects the occurrence of the vertical crack G4 in the glass ribbon G. In other words, the occurrence of the crack g4 in the glass sheet g is regarded as the occurrence of the vertical crack G4 in the glass ribbon G. The second threshold value is set to a value that satisfies this situation.

[0122] In this case, according to Fig.16 When the illustrated thermal image F5 detects that the crack damage g4 has occurred in the glass sheet g, it is considered that the longitudinal crack G4 has occurred in the glass ribbon G, and the cutting device 2 is moved to the retreat position based on the control signal from the control unit 33. The retreat position is a position where glass pieces and glass powder from the glass ribbon G are not easy to fall to the cutting device 2. At the retreat position, glass pieces and the like attached to the cutting device 2 are removed by cleaning. Thus, when the forming of the glass ribbon G is restarted and the cutting device 2 is returned to the original position, it is possible to prevent the glass ribbon G and the glass sheet g from being damaged by the glass pieces and glass powder remaining in the cutting device 2.

[0123] The glass plate manufacturing apparatus detects defects occurring in the measurement objects g and Gt based on the measurement results of the measurement objects g and Gt, and although it cannot identify the types of defects, it can be configured to identify defects by type. In this case, post-processing can be performed by subdividing the defects by type.

[0124] According to the glass plate manufacturing apparatus having the above-described structure, it is possible to detect defects occurring in the measurement objects g and Gt with high accuracy. However, in order to further improve the accuracy of defect detection, the following structure may be adopted.

[0125] As the first structure, Fig.17As shown, a plurality of (three in the example) thermal imagers 31 are arranged along the width direction. These thermal imagers 31 are arranged at equal intervals in the width direction and are arranged at the same height position. This height position is the same as the height position in the case where one thermal imager 31 is arranged as described above. In addition, the separation distance and separation method of these thermal imagers 31 from the measurement objects Gt, g are also the same as the separation distance and separation method in the case where one thermal imager 31 is arranged as described above.

[0126] In the measurement of temperature distribution by these thermal imagers 31, a plurality of (three in this embodiment) thermal images are obtained. Fig.18 As shown, the regions 35 in which the plurality of thermal imagers 31 can measure the measuring objects g and Gt are arranged in a row in the width direction. In these regions 35, adjacent regions 35 partially overlap (the overlapping portion is indicated by the reference numeral 35x), and cover the entire width direction region of the measuring objects g and Gt. Therefore, the plurality of thermal images are also obtained by photographing the measuring objects g and Gt in the same manner as the measurable regions 35 and 35x. That is, the plurality of thermal images become thermal images in which adjacent thermal images partially overlap, and become thermal images obtained by photographing the entire width direction region of the measuring objects g and Gt. Thus, the thermal images of the plurality of thermal imagers 31 can be used to detect defects generated in the measuring objects g and Gt without omission. And, when a defect of the cut side end Gt of the glass sheet g or the glass ribbon G is detected by any of the thermal images of the plurality of thermal imagers 31, the cut side end Gt of the glass sheet g or the glass ribbon G is defective. On the other hand, if the defect of the cut side end Gt of the glass sheet g or the glass ribbon G is not detected by all the thermal images, the cut side end Gt of the glass sheet g or the glass ribbon G is not defective. In this case, an anti-reflection member (not shown) is arranged in front of each thermal imager 31 by bonding or the like. If the anti-reflection member is not arranged, the detection accuracy when detecting a defect using each thermal imager 31 may be reduced due to the reflected light of the lighting or the like. According to the configuration here, the presence of the anti-reflection member makes it less susceptible to the negative influence caused by the reflected light of the lighting or the like.

[0127] As a second structure, Fig.19 As shown in FIG. 1 , each thermal imager 31 is arranged so as to measure the temperature distribution of the measurement objects g and Gt from obliquely below. Figure 20 to Figure 23 In this case, the angle α between the direction C of each thermal imager 31 pointing to the surface of the glass plate g and the horizontal direction is 3° to 80° (preferably, the lower limit is 30° and the upper limit is 60°).

[0128] According to the second structure, when the glass plate g is in a vertical position, that is, in a vertical position as shown by the solid line in the figure or in a substantially vertical position as shown by the dashed line in the figure (for example, an inclined position with an angle β of 15° or less relative to the vertical direction), the following advantages are obtained. Fig. 20 As shown, when the thermal imager 31 measures the glass plate g from obliquely below, the area 35 where the glass plate g can be measured is longer in the vertical direction than the area 35a where the glass plate g can be measured when the measurement is performed in the horizontal direction. Therefore, defects occurring in the glass plate g can be detected in a wider measurement area.

[0129] In addition, according to the second structure, the following advantages are also obtained. That is, when the thermal imager 31 is measured in the horizontal direction or when the thermal imager 31 is measured from an oblique upper direction, it is necessary to set the thermal imager 31 at a relatively higher position (for example, Fig.19 In this case, the thermal imager 31 may interfere with the scribed line forming device 21 and other devices outside the figure, and the degree of freedom of the installation space of the thermal imager 31 is reduced. In this second structure, compared with the case of measuring from the horizontal direction or obliquely upward as described above, the thermal imager 31 can be placed as shown in FIG. Fig.19 As shown in the figure, the thermal imager 31 is installed at a relatively low position. As a result, the thermal imager 31 is unlikely to interfere with the scribed line forming device 21 and other devices outside the figure, and the degree of freedom of the installation space of the thermal imager 31 is increased.

[0130] As a third structure, Fig.21 As shown in FIG. 1 , each thermal imager 31 can adjust the direction C of the surface of the glass plate g in the vertical direction. Specifically, each thermal imager 31 can rotate in the DD direction around the fulcrum 31s on its central axis. Therefore, by changing the direction C of each thermal imager 31, the area of ​​the glass plate g that can be measured changes in the vertical direction. In this case, the adjustment of the direction C of each thermal imager 31 can be performed simultaneously by linking all the thermal imagers 31, or can be performed separately at different times.

[0131] According to the third configuration, it is possible to appropriately deal with the disadvantages that may be caused when the size, thickness, type, etc. of the glass ribbon G formed and conveyed in the forming area 11 is changed, or when the glass sheet g is shaken even if there is no such change. That is, when such a change or swing occurs, the position of the cut glass sheet g may be shifted in the vertical direction. If such a position shift occurs, not only the detection accuracy of the defect generated in the glass sheet g is reduced, but also, depending on the situation, part or all of the glass sheet g may be separated from the area that can be measured by the thermal imager 31, so that the defect cannot be detected. According to the configuration here, by adjusting the direction C of the thermal imager 31 in the vertical direction, the area that can be measured by the thermal imager 31 can be shifted corresponding to the vertical deviation of the glass sheet g. As a result, the area that can be measured by the thermal imager 31 is appropriately corrected, and the detection of the defect is further improved in accuracy.

[0132] As the fourth structure, Fig. 22 As shown in the top view, each thermal imager 31 can adjust the direction C of the surface of the glass plate g in the width direction. Specifically, each thermal imager 31 can rotate in the EE direction around the fulcrum 31t on its central axis. Therefore, by changing the direction C of the thermal imager 31, the area of ​​the glass plate g that can be measured changes along the width direction. In this case, the adjustment of the direction C of each thermal imager 31 can be performed simultaneously by linking all the thermal imagers 31, or can be performed separately at different times.

[0133] According to the fourth configuration, even if the glass sheet g after the same change, swing or cut is offset in the width direction as described above, the area of ​​the glass sheet g measurable by the thermal imager 31 can be appropriately corrected by adjusting the direction of the thermal imager 31 in the width direction.

[0134] As the fifth structure, Fig.23 As shown, each thermal imager 31 can adjust the position in the up-down direction. Specifically, each thermal imager 31 can move in parallel in the up-down direction (FF direction). Therefore, by changing the up-down position of the thermal imager 31, the area of ​​the glass plate g can be measured to change in the up-down direction. In this case, the adjustment of the up-down position of each thermal imager 31 can be performed simultaneously by linking all the thermal imagers 31, or can be performed separately at different times.

[0135] According to the fifth configuration, even if the glass sheet g after the same change, swing or cut is shifted in the vertical direction as described above, the area where the glass sheet g can be measured by the thermal imager 31 can be appropriately corrected by adjusting the vertical position of the thermal imager 31.

[0136] It should be noted that, regarding the third, fourth, and fifth structures described above, only one of these structures may be provided, or two structures arbitrarily selected from these structures may be provided, or the three structures described above may be provided.

[0137] As a sixth configuration, initial settings and more detailed image analysis for detecting defects are performed on the thermal image obtained by the measurement of the thermal imager 31 . Fig.24 is a thermal image Fw of the thermal imager 31 disposed at the end portion (left end portion) in the width direction, Fig.25 It is a thermal image Fx of the thermal imager 31 set at a location other than the two ends in the width direction. As an initial setting, a defect inspection area 36 is set on the thermal images Fw and Fx shown in the above figures, respectively, with the upper end (cut side end) gt of the glass plate g and the space Z1 above it as the object. Among the defect inspection areas 36 set on all the multiple (three) thermal images Fw and Fx, adjacent defect inspection areas 36 partially overlap and cover the entire area in the width direction of the upper end gt of the glass plate g.

[0138] First of all, Fig.24 1. The method of setting the defect inspection area 36 on the thermal image Fw shown in FIG. 1 is described below. First, on the thermal image Fw, the upper edge ga1 (its height position) of the glass plate g is detected, and the detected upper edge ga1 is used as the origin position in the vertical direction. Here, the meaning of detecting the upper edge ga1 of the glass plate g is as follows. That is, when the cut surface ga on the upper side of the glass plate g is a straight line in the horizontal direction, the cut surface ga is detected as the upper edge ga1. On the other hand, when the cut surface ga on the upper side of the glass plate g is a wave shape or a shape inclined relative to the horizontal direction, for example, the highest part or the lowest part of the cut surface ga, or the middle part in the vertical direction between the highest part and the lowest part, etc. is detected as the upper edge ga1. In this case, when a phenomenon with a large height difference such as a wave shape or an inclined shape is clearly presented, the detection unit 32 can detect it as an obvious defect, so the setting here is not performed.

[0139] In addition, in the thermal image Fw, there is a boundary gf between the ear ge formed at the end of the glass plate g in the width direction and the portion gc closer to the center side in the width direction than the ear ge, so the boundary gf is detected and the boundary gf is used as the origin position in the width direction. It should be noted that the origin position in the width direction can also be the outer edge gf1 in the width direction of the ear ge. And, based on the origin position ga1 in the up-down direction and the origin position gf in the width direction, a rectangular inspection frame 37 that is long in the width direction is overlapped and drawn on the thermal image Fw. Thus, the internal area surrounded by the inspection frame 37 is set as the defective inspection area 36. On the thermal image Fw of this embodiment, the origin position ga1 in the up-down direction is positioned in the up-down direction center of the defective inspection area 36. In addition, one end (left end) in the width direction of the defective inspection area 36 is aligned to a position to the left of the origin position gf with the origin position gf in the width direction as a reference. Furthermore, the alignment is performed so that the other end (right end) of the defective inspection area 36 in the width direction exists at the right end of the thermal image Fw. Therefore, the defective inspection area 36 here becomes a region N extracted by a single inspection frame 37 so that the left end portion of the upper end gt of the glass plate g becomes the inspection object. It should be noted that the same initial setting as above is also performed for the thermal image Fw of the thermal imager 31 provided at the right end in the width direction.

[0140] According to this method, even when the vertical position and the width position of the glass plate g depicted on the thermal image Fw cannot be consistently determined, the vertical position and the width position of the defect inspection area 36 for the glass plate g on the thermal image Fw are consistently determined. As a result, it is less likely to cause erroneous detection when detecting a defect generated in the glass plate g by image analysis in the defect inspection area 36 (described later), and the defect detection accuracy can be further reliably improved.

[0141] Next, Fig.25 The method of setting the defective inspection area 36 on the thermal image Fx shown in the figure is described. In this case, the width direction end of the glass plate g is not presented on the thermal image Fx, so there is no need to detect the origin position in the width direction. Therefore, the alignment is performed in such a way that the two ends of the width direction of the defective inspection area 36 are respectively present at the two ends in the width direction of the thermal image Fx. In addition, on the thermal image Fx, the process of determining the origin position ga1 in the up and down directions and setting the defective inspection area 36 using the inspection frame 37 is also performed. Therefore, the defective inspection area 36 here becomes an area M extracted by an inspection frame 37 in such a way that the central part in the width direction of the upper end gt of the glass plate g becomes the inspection object. The method performed at this time is the same as the method based on the description already. Fig.24Therefore, according to the method here, if the content based on the origin position in the width direction is excluded, the result is the same as the method based on Fig.24 The method has the same effect.

[0142] Fig.26 An example of a form of a portion of the area N(M) extracted by the inspection frame 37 is shown. In this portion of the area N(M), a shape defect caused by a wave shape occurs on the cut surface ga on the upper side of the glass plate g. It should be noted that the origin position ga1 in the up-down direction shown in the figure is located in the up-down center between the lowest part and the highest part of the wave shape (including the wave shape in other areas). In addition, in the figure, the wave shape is exaggerated. This portion of the area N(M) is composed of a plurality of unit pixel groups Pk that are grid-shaped and separated vertically and horizontally. A unit pixel group Pk is a collection of a plurality of pixels. In this portion of the area N(M), the brightness of the set of unit pixel groups Pk arranged in a horizontal row at the bottom (the set marked with a circle in the figure) is set to a reference brightness equivalent to the reference temperature. And, based on the brightness difference with the reference brightness, the boundary between the upper end gt of the glass plate g and the space Z1 above it is determined. Under such setting, a unit pixel group Pk including the boundary between the upper end gt of the glass plate g and the space Z1 above it is extracted from a plurality of unit pixel groups Pk existing above the set of unit pixel groups Pk marked with a circle in the figure. In the figure, the plurality of unit pixel groups Pk including the above boundary extracted here are marked with an "×". Furthermore, the number of unit pixel groups Pk corresponding to the height difference from the unit pixel group Pk located at the bottom to the unit pixel group Pk located at the top is obtained among the plurality of unit pixel groups Pk extracted here (that is, the number of layers with an "×" when one horizontal row is set as one layer). And, when the obtained number is greater than the preset number, the detection unit 32 detects that the shape defect is caused by the wave shape, and when the obtained number is less than the preset number, the detection unit 32 detects that there is no shape defect caused by the wave shape. In the example, the obtained number is four and the preset number is three, so the detection unit 32 detects that the shape defect caused by the wave shape has occurred. It should be noted that this image analysis method can be similarly applied even when the cut surface ga on the upper side of the glass plate g has shape defects due to the protrusions g1 and the notches g2 described above.

[0143] According to this image analysis method, the boundary is identified based on the origin position ga1 in the vertical direction (including the origin position gf in the width direction as needed) using the constant position of the glass plate g as the reference brightness, so that it is possible to suppress the occurrence of deviations and errors in the identification of the boundary each time the inspection is performed. In addition, the occurrence of defects can be detected by simply finding the number of pixels corresponding to the height difference for the boundary identified by the brightness difference from the reference brightness, thereby ensuring the ease of image analysis and further accuracy.

[0144] Fig. 27 Another form of a part of the region N(M) extracted by the check frame 37 is illustrated. In this part of the region N(M), a defect caused by a local break g3 occurs on the cut surface ga on the upper side of the glass plate g. Here, in this part of the region N(M), the number of each unit pixel group Pk that is grid-shaped and divided vertically and horizontally is greater than the above case. Therefore, the number of pixels in one unit pixel group Pk is smaller than the above case. In addition, in this part of the region N(M), there is an origin position ga1 in the height direction at the boundary between the upper end gt of the glass plate g and the space Z1 above it (excluding the boundary with the local break g3). And, in the image analysis here, as in the above case, the boundary between the upper end gt of the glass plate g (including the local break g3) and the space Z1 above it is determined based on the brightness difference with the reference brightness, and the difference between the upper end gt and the space Z1 above it is also determined. Under this setting, a virtual straight line ga11 is drawn in the width direction along the origin position ga1 in the height direction. In this state, the area of ​​the region Zx surrounded by the contours g3a and g3b of the local break g3 and the virtual straight line ga11 is obtained based on the number of unit pixel groups Pk (or pixels Pk). If the obtained area value is greater than a preset area value (the area value of the missing portion of the glass plate g), the detection unit 32 detects that there is a local break g3, and if the obtained area value is less than the preset area value, the detection unit 32 detects that there is no local break g3. In the example, the obtained area value is greater than the preset area value, so the detection unit 32 detects that there is a local break g3.

[0145] Instead of this, the following method may be used. That is, the area of ​​the glass plate g excluding the above-mentioned area Zx (the area of ​​the glass plate g depicted in the portion of the area N (M)) may be calculated based on the number of unit pixel groups Pk (or pixels Pk). In this case, a value based on the area of ​​the glass plate g when the glass plate g is completely free of defects is pre-set (for example, the first threshold value already described). In this way, when the calculated area value exceeds the preset area value, the detection unit 32 detects that there is no local damage g3, and when the calculated area value is less than the preset area value, the detection unit 32 detects that there is local damage g3. It should be noted that based on Fig. 27 The image analysis method can be similarly applied when the cut surface ga on the upper side of the glass sheet g has the shape defects caused by the protrusion g1 and the notch g2 described above, and when the crack damage g4 described above occurs in association with the vertical crack of the glass ribbon G. In particular, when detecting the crack damage g3 associated with the vertical crack of the glass ribbon G, since it is possible to depict a mode in which the glass sheet g is completely absent in at least one of the multiple thermal images of the multiple thermal imagers 31, there is a case where the crack damage g3 can be detected even if the area value is not calculated based on the number of pixels.

[0146] According to this image analysis method, the constant position of the glass plate g is used as the reference brightness based on the origin position ga1 in the vertical direction (including the origin position gf in the width direction as appropriate), and the difference between the boundary and the upper end gt and the upper space Z1 is distinguished. Therefore, it is possible to suppress the occurrence of deviations and errors in the distinction of the boundary and the above differences each time the inspection is performed. In addition, in the area N (M) where the position correction is performed based on the above origin position ga1 (gf), the occurrence of defects can be detected only by calculating the area value from the number of pixels, thereby ensuring the ease of image analysis and further accuracy.

[0147] Next, a glass plate manufacturing method using the glass plate manufacturing apparatus having the above-described structure will be described.

[0148] The glass sheet manufacturing method of the present embodiment includes a forming step, a conveying step, a cutting step, and a detecting step.

[0149] The forming step is a step of forming the glass ribbon G in the forming zone 11 .

[0150] The conveying step is a step of conveying the formed glass ribbon G by the roller pair R of the conveying device 14. In addition, the conveying step includes a heat treatment step and a cooling step.

[0151] The heat treatment step is a step of heat-treating the glass ribbon G while conveying the glass ribbon G that has undergone the forming step in the heat treatment zone 12 .

[0152] The cooling step is a step of cooling the glass ribbon G that has undergone the heat treatment step while conveying it in the cooling zone 13 .

[0153] The cutting step is a step of cutting the glass ribbon G in the width direction by the cutting device 2 while conveying the glass ribbon G that has undergone the cooling step, thereby obtaining a glass sheet g.

[0154] The detection step is a step of measuring the temperature distribution of the measurement object including the cut side end Gt of the glass ribbon G and the glass plate g using the thermal imager 31 and detecting whether a defect occurs in the measurement object Gt, g based on the measurement result as described in detail.

[0155] As mentioned above, although the glass plate manufacturing apparatus and the manufacturing method thereof which concern on embodiment of this invention were demonstrated, embodiment of this invention is not limited to this, Various changes can be implemented in the range which does not deviate from the summary of this invention.

[0156] In the above-mentioned embodiment, the distribution of the height position of the cut surface is obtained based on the thermal image representing the temperature distribution of the thermal imager, and the shape defects of the cut surface of the measuring object are detected based on the height of the height position. However, the shape defects of the cut surface of the measuring object can also be detected by image analysis other than this.

[0157] In the above-mentioned embodiment, local breakage of the glass sheet g and vertical cracks of the glass ribbon G are detected based on the area of ​​the glass sheet g and the threshold value, but local breakage and vertical cracks may be detected by image analysis other than this. In addition, the area of ​​the glass sheet g may be obtained as the entire area of ​​the glass sheet g or as a part of the area of ​​the glass sheet g. For example, the area of ​​the middle part excluding the two end parts of the glass sheet g held by the chuck 27 may be obtained, and local breakage of the glass sheet g and vertical cracks of the glass ribbon G may be detected based on the area of ​​the middle part and the threshold value.

[0158] In the above embodiment, the temperature of the measurement object Gt, g is measured as the temperature distribution measurement by the thermal imager 31, but instead of this, the temperature distribution of the measurement object Gt, g can be measured using a linear sensor thermometer that can measure temperature in a linear shape.

[0159] In the above-mentioned embodiment, the measurement object is set to include both the cutting side end Gt of the glass ribbon G and the glass plate g, but only one of the two may be made the measurement object.

[0160] In the above embodiment, projections, notches, wavy shapes, local damage, and damage associated with longitudinal cracks are generated in a single measurement object, and these defects are detected separately for each measurement object, but sometimes multiple defects among these defects are simultaneously generated in a single measurement object. In this case, multiple defects (the presence or absence of these defects) can also be detected for a single measurement object.

[0161] In the above-mentioned embodiment, although the glass ribbon G is formed by the overflow down-draw method, it may be formed by other down-draw methods such as a slot down-draw method and a re-draw method, a float process, or the like.

[0162] In the above embodiment, the glass ribbon G is cut by breaking along the score line S, but it may be cut by other methods such as laser cutting, laser melting, etc. Even in the case of adopting this method, vibration and impact are generated when the glass sheet g is cut from the glass ribbon G, so the glass ribbon G and the glass sheet g may swing, but in the present invention, it is not easy to be negatively affected by such swing.

[0163] In the above embodiment, Figures 9 to 14 The thermal images shown are part of a thermal image of a thermal imager, but these thermal images can also be a part of a thermal image of multiple thermal imagers (see Fig.17 ) of each thermal image. In such a case, it is also possible to detect a poor Fig.26 as well as Fig. 27 The glass ribbon is not depicted in the thermal image as shown. Fig.15 as well as Fig.16 The thermal image shown in FIG. 1 depicts the entire glass sheet, but only the upper portion (e.g., the upper end portion) of the glass sheet may be depicted. In this case, only a portion of the width direction of the glass sheet may be depicted (the glass ribbon may also depict only a portion of the width direction). In such a case, when a defect is detected, Fig.26 as well as Fig. 27 The glass ribbon is not depicted as shown.

[0164] Description of Reference Numerals

[0165] 1 processing device, 2 cutting device, 3 detection device, 11 forming area, 14 conveying device, 22 breaking device, 31 thermal imager, 32 detection unit, 36 defect inspection area, F1 thermal image, F2 thermal image, F3 thermal image, F4 thermal image, F5 thermal image, Fw thermal image, Fx thermal image, G glass ribbon, Gt cut side end of glass ribbon, g glass plate, G1 protrusion, g1 protrusion, G2 notch, g2 notch, G3 local damage, g3 local damage, G4 longitudinal crack, g4 longitudinal crack, Ga cut surface on the lower side of glass ribbon, ga cut surface on the upper side of glass plate, ga1 origin position in the up and down direction (upper edge of glass plate), Gm molten glass, Z1 space above glass plate.

Claims

1. A method for manufacturing a glass sheet, comprising: A forming process, forming the glass ribbon in a forming area; A conveying step of conveying the glass ribbon along a length direction; and a cutting step of cutting the glass ribbon in a width direction to produce a glass sheet, The glass plate manufacturing method is characterized in that: The glass sheet manufacturing method includes the following detection step: taking at least one of the cut side end of the glass ribbon cut in the cutting step and the glass sheet as a measurement object, measuring the temperature of the measurement object, and detecting a defect that has occurred in the measurement object based on the measurement result of the measurement object, In the forming step, the glass ribbon is formed by a down-draw method. In the detection step, the temperature of the measurement object in the vertical posture is measured as a temperature distribution measurement using a thermal imager. The defect detected in the detection step includes a shape defect of a cut surface on the upper side of the glass sheet cut in the cutting step. The distribution of the height positions of the upper cut surface is obtained based on the temperature distribution of the glass sheet, and the shape defect of the upper cut surface is detected based on the height of the height positions.

2. The method for manufacturing a glass sheet according to claim 1, wherein: When a defective shape of the upper cut surface is detected, the glass sheet is discarded.

3. A method for manufacturing a glass sheet, comprising: A forming process, forming the glass ribbon in a forming area; A conveying step of conveying the glass ribbon along a length direction; and a cutting step of cutting the glass ribbon in a width direction to produce a glass sheet, The glass plate manufacturing method is characterized in that: The glass sheet manufacturing method includes the following detection step: taking at least one of the cut side end of the glass ribbon cut in the cutting step and the glass sheet as a measurement object, measuring the temperature of the measurement object, and detecting a defect that has occurred in the measurement object based on the measurement result of the measurement object, In the forming step, the glass ribbon is formed by a down-draw method. In the detection step, the temperature of the measurement object in the vertical posture is measured as a temperature distribution measurement using a thermal imager. The defect detected in the detection step includes a local breakage of the glass sheet after being cut in the cutting step. The area of ​​at least a portion of the glass sheet is calculated based on the temperature distribution of the glass sheet, and the local damage is detected based on the area and a first threshold value. The first threshold value is determined by the area of ​​the at least a portion of the region of the glass sheet when there is no defect at all.

4. The method for manufacturing a glass sheet according to claim 3, wherein: When the local breakage is detected, the glass plate is discarded.

5. A method for manufacturing a glass sheet, comprising: A forming process, forming the glass ribbon in a forming area; A conveying step of conveying the glass ribbon along a length direction; and a cutting step of cutting the glass ribbon in a width direction to produce a glass sheet, The glass plate manufacturing method is characterized in that: The glass sheet manufacturing method includes the following detection step: taking at least one of the cut side end of the glass ribbon cut in the cutting step and the glass sheet as a measurement object, measuring the temperature of the measurement object, and detecting a defect that has occurred in the measurement object based on the measurement result of the measurement object, In the forming step, the glass ribbon is formed by a down-draw method. In the detection step, the temperature of the measurement object in the vertical posture is measured as a temperature distribution measurement using a thermal imager. The defect detected in the detection step includes crack damage of the glass sheet accompanying the vertical crack of the glass ribbon cut in the cutting step, The area of ​​at least a portion of the glass sheet is calculated based on the temperature distribution of the glass sheet, and the crack is detected based on the area and a second threshold value. The second threshold value is determined by the area of ​​the at least a portion of the region of the glass sheet when there is no defect at all.

6. The method for manufacturing a glass sheet according to claim 5, wherein: When the crack breakage is detected, it is regarded that a vertical crack of the glass ribbon has occurred, and the cutting device used for executing the cutting step is retracted.

7. A method for manufacturing a glass sheet, comprising: A forming process, forming the glass ribbon in a forming area; a conveying step of conveying the glass ribbon along the length direction; and a cutting step of cutting the glass ribbon along the width direction to cut out a glass sheet. The glass plate manufacturing method is characterized in that: The glass sheet manufacturing method includes the following detection step: taking at least one of the cut side end of the glass ribbon cut in the cutting step and the glass sheet as a measurement object, measuring the temperature of the measurement object, and detecting a defect that has occurred in the measurement object based on the measurement result of the measurement object, In the forming step, the glass ribbon is formed by a down-draw method. In the detection step, the temperature of the measurement object in the vertical posture is measured as a temperature distribution measurement using a thermal imager. On the thermal image obtained by measuring the temperature distribution using the thermal imager, the height position of the upper edge of the cut glass plate is detected, and the detected height position is used as the origin position in the up-down direction. A defect inspection area is set with the upper end of the glass plate and the space above the upper end as the objects, and defects that have occurred in the glass plate are detected by image analysis in the defect inspection area.

8. The method for producing a glass plate according to any one of claims 1 to 7, wherein: In the cutting step, the glass ribbon is broken along a score line extending in the width direction of the glass ribbon to cut out the glass sheet.

9. The method for producing a glass plate according to any one of claims 1 to 7, wherein: The thermal imager measures the temperature distribution of the measurement object from obliquely below.

10. The method for producing a glass plate according to any one of claims 1 to 7, wherein: The thermal imager can adjust the direction toward the surface of the measurement object in the up-down direction.

11. The method for producing a glass plate according to any one of claims 1 to 7, wherein: The thermal imager can be adjusted in a width direction toward the surface of the measurement object.

12. The method for producing a glass plate according to any one of claims 1 to 7, wherein: The thermal imager can adjust the position in the up and down directions.

13. A glass sheet manufacturing device, comprising: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a length direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet. The glass sheet manufacturing device is characterized in that: The glass sheet manufacturing device includes a detection device, which uses at least one of the cut side end of the glass ribbon cut by the cutting device and the glass sheet as a measurement object, measures the temperature of the measurement object, and detects a defect that has occurred in the measurement object based on the measurement result of the measurement object. The detection device is equipped with a thermal imager. In the forming zone, the glass ribbon is formed by a down-draw method, The thermal imager measures the temperature of the measurement object in a vertical posture as a measurement of temperature distribution. The defect detected by the detection device includes a shape defect of a cut surface on the upper side of the glass sheet cut by the cutting device. The detection device obtains the distribution of the height positions of the upper cut surface based on the temperature distribution of the glass sheet, and detects shape defects of the upper cut surface based on the height positions.

14. A glass sheet manufacturing device, comprising: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a length direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet. The glass sheet manufacturing device is characterized in that: The glass sheet manufacturing device includes a detection device, which uses at least one of the cut side end of the glass ribbon cut by the cutting device and the glass sheet as a measurement object, measures the temperature of the measurement object, and detects a defect that has occurred in the measurement object based on the measurement result of the measurement object. The detection device is equipped with a thermal imager. In the forming zone, the glass ribbon is formed by a down-draw method, The thermal imager measures the temperature of the measurement object in a vertical posture as a measurement of temperature distribution. The defect detected by the detection device includes a local breakage of the glass sheet cut by the cutting device. The detection device calculates the area of ​​at least a portion of the glass plate according to the temperature distribution of the glass plate, and detects the local damage based on the area and a first threshold value. The first threshold value is determined by the area of ​​the at least a portion of the region of the glass sheet when there is no defect at all.

15. A glass sheet manufacturing device, comprising: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a length direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet. The glass sheet manufacturing device is characterized in that: The glass sheet manufacturing device includes a detection device, which uses at least one of the cut side end of the glass ribbon cut by the cutting device and the glass sheet as a measurement object, measures the temperature of the measurement object, and detects a defect that has occurred in the measurement object based on the measurement result of the measurement object. The detection device is equipped with a thermal imager. In the forming zone, the glass ribbon is formed by a down-draw method, The thermal imager measures the temperature of the measurement object in a vertical posture as a measurement of temperature distribution. The defect detected by the detection device includes crack breakage of the glass sheet accompanying the vertical crack of the glass ribbon cut by the cutting device. The detection device calculates the area of ​​at least a portion of the glass plate according to the temperature distribution of the glass plate, and detects the crack damage based on the area and a second threshold value. The second threshold value is determined by the area of ​​the at least a portion of the region of the glass sheet when there is no defect at all.

16. A glass sheet manufacturing device, comprising: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a length direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet. The glass sheet manufacturing device is characterized in that: The glass sheet manufacturing device includes a detection device, which uses at least one of the cut side end of the glass ribbon cut by the cutting device and the glass sheet as a measurement object, measures the temperature of the measurement object, and detects a defect that has occurred in the measurement object based on the measurement result of the measurement object. The detection device is equipped with a thermal imager. In the forming zone, the glass ribbon is formed by a down-draw method, The thermal imager measures the temperature of the measurement object in a vertical posture as a measurement of temperature distribution. The detection device detects the height position of the upper edge of the cut glass plate on the thermal image obtained by measuring the temperature distribution using the thermal imager, uses the detected height position as the origin position in the up-down direction, sets a defect inspection area with the upper end of the glass plate and the space above the upper end as the object, and detects defects that have occurred in the glass plate by image analysis in the defect inspection area.

Images