Glass plate manufacturing method and manufacturing device

Abstract

A glass plate g is cut out by cutting a glass ribbon G along the width direction by means of a cutting device 2 while molding the glass ribbon G in a molding zone 11 and conveying the glass ribbon G in the longitudinal direction by means of a conveying device 14, after which a cut-side end portion Gt of the glass ribbon G and the glass plate g serve as measurement targets . The temperature of the measurement targets Gt and g is measured, and defects generated in the measurement targets Gt and g are detected on the basis of the measurement results.

Description

[Technical field]

[0001] The present invention relates to a glass sheet manufacturing technology, and more particularly to detection of defects occurring in a glass ribbon or a glass sheet after the glass ribbon is cut to obtain glass sheets. [Background technology]

[0002] As a method for producing a glass sheet, a method using a downdraw method, typically an overflow downdraw method, a slot downdraw method, or a redraw method, is widely adopted.

[0003] In the manufacturing process of a glass sheet using these techniques, a glass ribbon is continuously formed, and then the glass ribbon is cut along the width direction at predetermined lengths to cut out glass sheets from the glass ribbon. During this process, defects may occur in the glass ribbon or the glass sheet.

[0004] Therefore, for example, Patent Document 1 discloses a method in which a plurality of laser sensors are used to detect the presence or absence of glass in a glass ribbon or glass sheet after cutting, and defects (called breakage in the document) occurring therein are automatically monitored based on the detection results. The laser sensors used here are reflective sensors that irradiate laser light toward the glass ribbon or glass sheet and detect the light reflected by the glass. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-104228 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of a laser sensor, when the glass ribbon or glass sheet sways or vibrates on the transport path, the state of the light to be measured, such as the reflected light obtained from the laser light irradiated toward them, easily fluctuates. As a result, there is a problem of false detection of defects occurring in the glass ribbon or glass sheet, and it is desired to detect these defects with higher accuracy.

[0007] From the above viewpoints, the present invention aims to detect defects occurring in a measurement object, which is either the cut side end of the glass ribbon after cutting, a glass plate, or both, with high accuracy. [Means for solving the problem]

[0008] The first aspect of the present invention, which has been invented to solve the above problems, is a glass sheet manufacturing method including a forming step of forming a glass ribbon in a forming zone, a conveying step of conveying the glass ribbon along a longitudinal direction, and a cutting step of cutting the glass ribbon along a width direction to cut out a glass sheet, characterized in that the method includes a detection step of measuring the temperature of the measurement object, which is either the cut end of the glass ribbon after cutting in the cutting step, a glass sheet, or both, and detecting a defect occurring in the measurement object based on the measurement result. Here, "defect" means a defect such as a defect (including an irregular shape) or breakage occurring in the measurement object, and a measurement object in which such a defect occurs is itself a defect (defective product) (the same applies below).

[0009] According to this method, when the measurement object is the cut-side end of the glass ribbon, defects occurring at the cut-side end are detected, when the measurement object is a glass plate, defects occurring in the glass plate are detected, and when the measurement object is both the cut-side end of the glass ribbon and the glass plate, defects occurring in the cut-side end and the glass plate are detected. When detecting defects, the temperature of the measurement object does not change significantly even if the position of the measurement object fluctuates due to shaking or vibration on the transport path, but shows a large change at the points where glass is missing or protruding in the measurement object. Therefore, according to this method, defects occurring in the measurement object can be detected with high accuracy.

[0010] In this method, in the cutting step, the glass ribbon may be broken along scribe lines extending in a width direction thereof to cut out the glass plate.

[0011] In this way, it is possible to detect with high accuracy specific defects that occur in the cut end of the glass ribbon or the glass sheet after cutting when the glass ribbon is cut by folding and breaking. That is, in the cutting process, the glass ribbon can be cut by laser cleaving, laser melting, or the like, but when the glass ribbon is cut by folding and breaking, specific defects different from those caused by other methods occur. According to the configuration here, it is possible to appropriately deal with such specific defects.

[0012] In the above method, the forming step may form the glass ribbon by a down-draw method, and the detection step may measure the temperature of the measurement object in a vertical position by measuring the temperature distribution using a thermograph. Here, the vertical position refers to a vertical position or an inclined position that is less than 45° with respect to the vertical direction (hereinafter the same).

[0013] The temperature distribution can be measured using multiple temperature sensors arranged across the width of the vertically oriented glass ribbon or glass plate; however, by using thermography, it is possible to obtain highly accurate temperature distribution and reliably detect even small defects.

[0014] In this method, the defects detected in the detecting step may include a shape defect of the cut surface on the upper side of the glass plate after cutting in the cutting step.

[0015] Defective shapes on the upper cut surface of the glass sheet are often caused by, for example, wear of the scribe tip, the wheel cutter, etc. If this defective shape is detected, appropriate measures such as replacing the scribe tip or the wheel cutter, etc., can be taken, and the occurrence of defective shapes on the upper cut surface of the subsequent glass sheet can be suppressed.

[0016] In this method, a distribution of height positions of the upper cut surface may be obtained from a temperature distribution in the glass plate, and a shape defect of the upper cut surface may be detected based on the obtained height positions.

[0017] In this way, by measuring the height from the distribution of height positions on the cut surface on the upper side of the glass plate, it is possible to detect defects in the shape of the cut surface, and the detection process is optimized. In this case, the thermal image showing the temperature distribution by thermography depicts the boundary between the low-temperature area, which is the space above the glass plate, and the high-temperature area where the glass plate is present, as the shape of the cut surface. Then, by performing image analysis based on the height of this boundary line, it is possible to accurately detect defects in the shape of the cut surface.

[0018] In this method, if a defect in the shape of the upper cut surface is detected, the glass plate may be discarded.

[0019] In this way, when a defect in the shape of the upper cut surface is detected, the glass plate can be discarded early, and contamination of the manufacturing line in the subsequent process can be prevented.

[0020] In these methods, the defect detected in the detection step may include partial breakage of the glass sheet after cutting in the cutting step.

[0021] Partial breakage is likely to occur, for example, when the warp of the glass ribbon is large. If partial breakage is detected, appropriate measures such as reducing the warp of the glass ribbon can be taken, and partial breakage can be suppressed from occurring in the subsequent glass sheets.

[0022] In this method, an area of ​​at least a partial region of the glass plate may be calculated from a temperature distribution in the glass plate, and the partial breakage may be detected based on the area and a first threshold value.

[0023] In this way, partial damage is detected based on the area of ​​at least a part of the glass plate and the first threshold value, so that accurate detection with less error is possible. In this case, in the thermal image showing the temperature distribution by thermography, a low-temperature drawing corresponding to partial damage appears in a part of the part where a high-temperature drawing should be made due to the presence of the glass plate. Then, the area of ​​only the high-temperature part is obtained, and partial damage is detected based on this area and the first threshold value. In this case, the area of ​​the glass plate is, for example, the area of ​​the part of the glass plate when the area measurable by thermography is a part of the glass plate, and is the area of ​​the entire glass plate when the area measurable by thermography is the entire glass plate. This area can be obtained by the number of pixels in the thermal image, etc. The first threshold value here is set to, for example, 90% to 99% of the area of ​​the glass plate when no defects exist (the area corresponding to the above-mentioned area). Therefore, if the area of ​​the high-temperature part in the thermal image exceeds the first threshold value, it is determined that there is no partial damage, and if it is equal to or less than the first threshold value, it is detected as partial damage.

[0024] In this method, when the partial breakage is detected, the glass plate may be discarded.

[0025] In this way, when partial breakage is detected, the glass plate can be discarded early, thereby preventing contamination of the manufacturing line in the subsequent process.

[0026] In these methods, the defects detected in the detection step may include cracks or breakage of the glass sheet associated with vertical cracks in the glass ribbon after cutting in the cutting step.

[0027] In this way, cracks and breakage, which are defects different from the above-mentioned shape defects and partial breakage, can be detected from a thermal image showing the temperature distribution of the glass sheet by thermography. The cracks and breakage occur due to vertical cracks in the glass ribbon after cutting. Here, the vertical cracks refer to cracks formed along the vertical direction of the glass ribbon, and are such that the entire glass ribbon breaks over time. When the vertical cracks occur, the glass sheet cut out from the glass ribbon suffers from cracks and breakage larger than the above-mentioned partial breakage, and it may become impossible to cut out the glass sheet. According to the configuration here, the occurrence of such vertical cracks in the glass ribbon can be detected from a thermal image of the glass sheet, not the glass ribbon.

[0028] In this method, an area of ​​at least a partial region of the glass plate may be calculated from the temperature distribution in the glass plate, and the crack or breakage may be detected based on the area and a second threshold value.

[0029] In this way, the crack damage caused by the vertical crack described above is detected based on the area of ​​the glass plate and the second threshold value, so that accurate detection with less error is possible. In this case, in the thermal image showing the temperature distribution by thermography, a low temperature drawing corresponding to the crack damage appears in a part of the part where a high temperature drawing should be made due to the presence of the glass plate. The crack damage also includes a breakage where the glass plate is no longer present, in which case the high temperature part showing the presence of the glass plate disappears on the thermal image. Under such circumstances, the area of ​​the high temperature part (which may be zero) is obtained, and the crack damage is detected based on this area and the second threshold value. The area of ​​the glass plate in this case is also, as in the above case, for example, the area of ​​a part or the entire area of ​​the glass plate, and can be obtained by the number of pixels in the thermal image. The second threshold value here is set to, for example, 30% to 50% of the area of ​​the glass plate when there is no defect (the area corresponding to the above area). Therefore, if the area of ​​the high temperature part in the thermal image exceeds the second threshold value, it is determined not to be a crack damage, and if it is equal to or less than the second threshold value, it is detected as a crack damage. In addition, since the second threshold is a numerical value smaller than the above-mentioned first threshold, the above-mentioned partial damage is detected as a defect when it is equal to or smaller than the first threshold and exceeds the second threshold.

[0030] In this method, when the crack or breakage is detected, it may be determined that a vertical crack has occurred in the glass ribbon, and a cutting device used in carrying out the cutting step may be withdrawn.

[0031] In this way, when cracking or breakage of the glass sheet is detected, it is assumed that a vertical crack has occurred in the glass ribbon, and appropriate measures can be taken against the vertical crack. As described above in detail, cracking or breakage of the glass sheet occurs along with a vertical crack in the glass ribbon. Therefore, when it is detected that a cracking or breakage of the glass sheet has occurred, it is also detected that a vertical crack has occurred in the glass ribbon. That is, the occurrence of cracking or breakage of the glass sheet is assumed to be the occurrence of a vertical crack in the glass ribbon. The condition (for example, the above-mentioned second threshold value) that is the reference for determining whether or not it is cracking or breakage is set as a condition that satisfies such an event. From this viewpoint, according to the configuration here, when cracking or breakage of the glass sheet is detected, that is, when it is assumed that a vertical crack has occurred in the glass ribbon, the cutting device can be evacuated early. This makes it possible to prevent contamination or failure of the cutting device caused by a large amount of glass fragments or glass powder scattering and falling from the glass ribbon due to the occurrence of a vertical crack.

[0032] In these methods, the thermograph may measure the temperature distribution of the measurement object from an obliquely downward direction.

[0033] In this way, when the area that can be measured by the thermograph is a part of the area of ​​the measurement object (for example, if the measurement object is a glass plate, a part of the area in the vertical direction of the glass plate), the following advantages can be obtained. That is, when the measurement by the thermograph is performed from obliquely below, the area in which the measurement object can be measured is longer in the vertical direction than the area in which the measurement object can be measured when the measurement is performed along the horizontal direction. Therefore, the advantage of being able to detect defects occurring in a wide measurement area is obtained. In addition, the following advantages can be obtained. That is, when the measurement by the thermograph is performed along the horizontal direction or from obliquely above, it is necessary to install the thermograph at a relatively higher position than when it is performed from obliquely below. In such a case, there is a risk that the thermograph will interfere with peripheral devices (for example, devices for forming scribe lines, etc.) arranged around the cutting position of the glass ribbon, and the degree of freedom in the installation space of the thermograph is reduced. According to the configuration here, the thermograph can be installed at a relatively lower position compared to the above-mentioned case of performing the measurement from the horizontal direction or from obliquely above. This makes it less likely that the thermography will interfere with the peripheral devices described above, and increases the freedom in the installation space for the thermography.

[0034] In these methods, the direction in which the thermograph is directed toward the surface of the object to be measured may be adjustable in the vertical direction.

[0035] In this way, it is possible to appropriately deal with adverse effects that may occur when the size, thickness, variety, etc. of the glass ribbon to be formed and transported is changed, or when the measurement target is shaken even if no change is made. That is, when such a change or shake occurs, the position of the measurement target after cutting may be shifted in the vertical direction. When such a position shift occurs, not only the detection accuracy of defects occurring in the measurement target decreases, but in some cases, a part or all of the measurement target may deviate in the vertical direction from the area that can be measured by the thermography, making it impossible to detect the defect. According to the configuration here, by adjusting the direction of the thermography (the direction in which it is directed toward the surface of the measurement target) in the vertical direction, the area that can be measured by the thermography can be shifted in response to the vertical shift of the measurement target. As a result, the area in which the measurement target can be measured is appropriately corrected, and further high accuracy in defect detection is achieved.

[0036] In these methods, the direction in which the thermograph is directed toward the surface of the object to be measured may be adjustable in the width direction.

[0037] In this way, even if the size, thickness, variety, etc. of the glass ribbon is changed as described above, or the measurement object vibrates, causing the measurement object to shift in the width direction after cutting, the area in which the measurement object can be measured can be appropriately corrected by adjusting the orientation of the thermograph in the width direction.

[0038] In these methods, the thermography may be capable of adjusting its position in the vertical direction.

[0039] In this way, even if the size, thickness, or type of the glass ribbon is changed or the measurement target is swayed, the region in which the measurement target can be measured after cutting is appropriately corrected by adjusting the vertical position of the thermograph. In this case, the region in which the measurement target can be measured can be shifted in the vertical direction without changing the orientation of the thermograph or while changing its orientation.

[0040] In these methods, the height position of the upper edge of the glass plate after cutting may be detected on a thermal image obtained by measuring the temperature distribution using the thermograph, and this detected height position may be used as the origin position in the vertical direction to set a defect inspection area covering the upper end of the glass plate and the space above it, and defects occurring in the glass plate may be detected by image analysis within the defect inspection area.

[0041] In this way, the defect inspection area is set at an appropriate position on the thermal image of the thermograph, so that defects occurring on the glass plate can be detected with even higher accuracy. More specifically, the vertical position of the glass plate depicted on the thermal image is not uniformly determined. This is caused not only by the above-mentioned changes and vibrations, but also by the fact that the timing at which the thermograph captures the thermal image varies each time a measurement is performed. Under such circumstances, when the defect inspection area is set on the thermal image, there is a risk that the vertical position of the defect inspection area will vary or have errors, which may lead to erroneous detection of defects occurring on the glass plate. According to the configuration here, the height position of the upper edge of the glass plate depicted on the thermal image is detected, and the defect inspection area is set with the detected height position as the vertical origin position, so that the vertical position of the defect inspection area relative to the glass plate on the thermal image is uniformly determined. This makes it less likely that erroneous detection will occur when detecting defects occurring on the glass plate by image analysis within the defect inspection area, and the detection accuracy of defects can be improved more reliably.

[0042] A second aspect of the present invention, which has been devised to solve the above-mentioned problems, is a glass sheet manufacturing apparatus including a forming zone for forming a glass ribbon, a conveying device for conveying the glass ribbon along a longitudinal direction, and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet, characterized in that the apparatus includes a detection device that measures the temperature of the measurement object, the cut side end of the glass ribbon after cutting by the cutting device, a glass sheet, or either one of them, as a measurement object, and detects defects occurring in the measurement object based on the measurement results.

[0043] This makes it possible to obtain the same effects as those of the previously described manufacturing method having substantially the same configuration as this manufacturing apparatus. Effect of the Invention

[0044] According to the present invention, the cut side end of the glass ribbon after cutting, the glass sheet, or either one of them is set as a measurement object, and defects occurring in the measurement object can be detected with high accuracy. [Brief description of the drawings]

[0045] [Figure 1] 1 is a vertical sectional side view showing an overall configuration of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Diagram 2] 2 is a schematic front view showing a main part of the glass sheet manufacturing apparatus as viewed from a direction A in FIG. [Diagram 3] FIG. 2 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. [Figure 4a] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 4b] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 5a] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 5b] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 6] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 7] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 8] FIG. 2 is a front view showing, in an exaggerated manner, the shapes of a cut end portion of a glass ribbon and a glass sheet immediately after the glass ribbon is cut using the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 9] FIG. 2 is a schematic front view for explaining a method for detecting a first example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 10] FIG. 11 is a schematic front view for explaining a method for detecting a second example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 11] FIG. 11 is a front view showing a method for detecting a third example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 12] FIG. 11 is a schematic front view for explaining another technique for detecting a first example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 13] FIG. 11 is a schematic front view for explaining another technique for detecting a second example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 14] FIG. 11 is a schematic front view for explaining another method for detecting a third example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 15] FIG. 11 is a front view showing a method for detecting a fourth example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 16] FIG. 11 is a front view showing a method for detecting a fifth example of a defect in a glass sheet and a glass ribbon from a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 17] FIG. 2 is a schematic front view of a glass sheet manufacturing apparatus according to a modified example of an embodiment of the present invention, as viewed from a direction A in FIG. [Figure 18] FIG. 11 is a schematic front view showing a range that can be measured by a thermograph that is a component of a glass sheet manufacturing apparatus according to a modified example of an embodiment of the present invention. [Figure 19] FIG. 2 is a schematic side view showing a relationship between a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention, and a glass sheet. [Figure 20] FIG. 2 is a schematic side view showing a range in which a glass sheet can be measured by a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 21] FIG. 2 is a schematic side view showing a relationship between a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention, and a glass sheet. [Figure 22] FIG. 2 is a schematic plan view showing a relationship between a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention, and a glass sheet. [Figure 23] FIG. 2 is a schematic side view showing a relationship between a thermograph, which is a component of the glass sheet manufacturing apparatus according to the embodiment of the present invention, and a glass sheet. [Figure 24] FIG. 1 is a front view showing a method for setting a defect inspection area on a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Diagram 25] FIG. 1 is a front view showing a method for setting a defect inspection area on a thermal image of temperature distribution obtained by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 26]FIG. 1 is a front view showing a first example of a method for detecting defects by image analysis within a defect inspection area set on a thermal image of temperature distribution by a thermograph, which is a component of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 27] FIG. 11 is a front view showing a second example of a method for detecting defects by image analysis within a defect inspection area set on a thermal image of temperature distribution by a thermograph, which is a component of the glass sheet manufacturing apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0047] 1 is a vertical sectional side view showing an overall configuration of a glass sheet manufacturing apparatus according to the present embodiment. As shown in the drawing, the glass sheet manufacturing apparatus includes a processing device 1 for a glass ribbon G, a cutting device 2, and a detection device 3.

[0048] The processing device 1 includes a forming zone 11 for continuously forming a glass ribbon G, a heat treatment zone 12 for heat treating (slowly cooling) the glass ribbon G, a cooling zone 13 for cooling the glass ribbon G to approximately room temperature, and a conveying device 14 consisting of roller pairs R arranged in multiple stages above and below in each of the forming zone 11, the heat treatment zone 12, and the cooling zone 13.

[0049] The forming zone 11 and the heat treatment zone 12 are constituted by a furnace in which the periphery of the transport path of the glass ribbon G is surrounded by walls, and heating devices such as heaters for adjusting the temperature of the glass ribbon G are disposed at appropriate positions within the furnace. On the other hand, the cooling zone 13 is open to the external atmosphere at room temperature without the periphery of the transport path of the glass ribbon G being surrounded by walls, and no heating device such as a heater is disposed therein.

[0050] In the internal space of the forming zone 11, a forming body 15 is disposed, which forms a glass ribbon G from molten glass Gm by an overflow downdraw method. The molten glass Gm supplied to the forming body 15 overflows from a groove (not shown) formed in a top portion 15a of the forming body 15. The overflowing molten glass Gm flows along both side surfaces 15b, which have a wedge-shaped cross section, of the forming body 15 and joins at the lower end. In this way, a plate-shaped glass ribbon G is continuously formed. The continuously formed glass ribbon G is sent downward in a vertical position (preferably a vertical position).

[0051] The internal space of the heat treatment zone 12 has a predetermined temperature gradient downward. The glass ribbon G in the vertical position is heat treated (slowly cooled) so that the temperature decreases as it moves downward through the internal space of the heat treatment zone 12. This heat treatment reduces internal distortion of the glass ribbon G. The temperature gradient in the internal space of the heat treatment zone 12 is adjusted, for example, by a heating device provided on the inner wall surface of the heat treatment zone 12.

[0052] The multiple roller pairs R constituting the conveying device 14 clamp both widthwise ends of the glass ribbon G in a vertical position from both the front and back sides. The uppermost roller pair R arranged in the forming zone 11 is a cooling roller. Note that, in the internal space of the heat treatment zone 12, the multiple roller pairs R may include ones that do not clamp the side ends of the glass ribbon G. In other words, the opposing distance between the roller pairs R may be made larger than the thickness of both widthwise ends of the glass ribbon G, and the glass ribbon G may pass between the roller pairs R.

[0053] In this embodiment, both widthwise end portions of the glass ribbon G produced by the processing device 1 have portions (hereinafter also referred to as "ear portions") that are thicker than the widthwise central portion due to the influence of shrinkage during the molding process.

[0054] The cutting device 2 is configured to cut the glass ribbon G in a vertical position below the processing device 1 in the width direction at predetermined lengths, thereby sequentially cutting out glass plates from the glass ribbon G. The glass plates become original glass plates (mother glass plates) from which one or more product glass plates are obtained in a later process by removing the edge portions. Here, the width direction is a direction perpendicular to the longitudinal direction (transport direction) of the glass ribbon G, and in this embodiment, substantially coincides with the horizontal direction.

[0055] As shown in FIGS. 1 and 2, the cutting device 2 includes a scribe line forming device 21 and a breaking device 22.

[0056] The scribe line forming device 21 is a device that forms a scribe line S at a scribe line forming position P1 on a first main surface of the glass ribbon G in a vertical position that has descended from the processing device 1. In this embodiment, the scribe line forming device 21 includes a wheel cutter 23 that forms a scribe line S on the first main surface of the glass ribbon G along its width direction, and a support member 24 (e.g., a support bar or a support roller) that supports a second main surface of the glass ribbon G (the surface opposite to the first main surface) at a position corresponding to the wheel cutter 23.

[0057] The wheel cutter 23 and the support member 24 are configured to descend following the descending glass ribbon G, and form a scribe line S over the entirety or part of the width direction of the glass ribbon G. In this embodiment, the scribe line S is also formed on the edge portions, which have a relatively large thickness. The scribe line S may be formed by irradiating a laser or the like.

[0058] The slicing device 22 is a device that slicing the glass ribbon G along a scribe line S at a slicing position (cutting position) P2 provided below the scribe line forming position P1 to cut out a glass sheet. In this embodiment, the slicing device 22 includes a slicing member 25 that abuts against the region where the scribe line S is formed from the second main surface side, and a gripping mechanism 26 that grips a lower region of the glass ribbon G below the slicing position P2.

[0059] The breaking member 25 is composed of a plate-like body (plate) having a flat surface that descends following the descending glass ribbon G and contacts the entire 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 is curved in the width direction.

[0060] The gripping mechanism 26 includes chucks 27 disposed at multiple locations in the vertical direction at both widthwise ends of the glass ribbon G, and arms 28 (see FIG. 2) that hold the multiple chucks 27 at both widthwise ends. These arms 28 perform an operation (operation in the direction B) for bending the glass ribbon G with the breaking member 25 as a fulcrum while lowering the multiple chucks 27 to follow the glass ribbon G as it descends. This applies bending stress to the scribe line S and its vicinity, and the glass ribbon G is broken in the width direction along the scribe line S. As a result of cutting by this bending, a glass plate is cut out from the glass ribbon G. The chucks 27 may be changed to another holding form, such as holding the glass ribbon G by negative pressure adsorption.

[0061] As shown in Fig. 1 and Fig. 3, the detection device 3 is a device for detecting defects occurring in the measurement objects g and Gt, which are the cut-side end Gt of the glass ribbon G after being cut by the cutting device 2. In this embodiment, the detection device 3 includes a thermograph 31, a detection unit 32, a control unit 33, and an alarm unit 34. Here, the glass ribbon G and the glass sheet g have a width direction length of 1000 to 3500 mm and a thickness of 100 to 2000 µm. In addition, the glass sheet g has a vertical length (length in the up-down direction) of 800 to 3000 mm.

[0062] The thermograph 31 measures the temperature distribution of the measurement objects Gt, g, and is disposed below the height position of the wheel cutter 23 and above the lower end of the gripping mechanism 26. The thermograph 31 of this embodiment is disposed below the height position of the cleavage member 25 and above the lower end of the gripping mechanism 26. The thermograph 31 is disposed at the width direction center position of the measurement objects Gt, g on one main surface side (the first main surface side of the glass ribbon G) of the measurement objects Gt, g, spaced apart from the main surface. The distance of the thermograph 31 from the measurement objects Gt, g can be set arbitrarily within a range in which the temperature distribution of the measurement objects Gt, g can be measured without contact (for example, in the range of 800 to 3000 mm). The thermograph 31 may be disposed on the other main surface side of the measurement objects Gt, g.

[0063] The detection unit 32 performs image analysis on the thermal image showing the temperature distribution by the thermograph 31, and detects defects occurring 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 folding, not only does the glass ribbon G after cutting shake, but the glass sheet g also shakes due to the vibration or shaking of the gripping mechanism 26. In addition, when the glass ribbon G is thin or warped, the shaking of the glass ribbon G and the glass sheet g after cutting may become significant. However, since the detection unit 32 detects defects occurring in the measurement objects g and Gt from the temperature distribution by the thermograph 31, it is unlikely to be adversely affected by the shaking of the glass ribbon G and the glass sheet g.

[0064] When a defect is detected by the detection unit 32, the control unit 33 issues a control signal to cause the chuck 27 of the gripping mechanism 26 to perform gripping and release operations, and to move the cutting device 2 to a retreat position and a return position, etc.

[0065] The alarm unit 34 issues an alarm when the detection unit 32 detects a specific defect (for example, a crack or breakage g4 of the glass sheet g associated with a vertical crack G4 of the glass ribbon G, which will be described later). The alarm is notified to the worker by voice, display, or the like. The alarm unit 34 may be omitted.

[0066] 4a to 8 show examples of defects that can be detected by the detection unit 32. For the sake of convenience, the gripping mechanism 26 and the like are omitted from these figures.

[0067] The glass sheet g shown in FIG. 4a has a shape defect on the upper cut surface ga due to a horn (commonly known as) g1 in which the middle part in the width direction protrudes upward. The horn g1 is, for example, several mm in height and several mm in width. Due to this, the lower cut surface Ga of the glass ribbon G shown in the same figure has a shape defect due to a chip G2 in which the middle part in the width direction is recessed upward. Conversely, the glass sheet g shown in FIG. 4b has a shape defect on the upper cut surface ga due to a chip g2 in which the middle part in the width direction is recessed downward. The chip g2 is, for example, several mm in depth and several mm in width. Due to this, the lower cut surface Ga of the glass ribbon G shown in the same figure has a shape defect due to a horn G1 in which the middle part in the width direction protrudes downward.

[0068] In the glass sheet g shown in FIG. 5a, a shape defect occurs on the upper cut surface ga due to a horn g1 in which one end in the width direction protrudes upward. The horn g1 is, for example, several mm in height and several mm in width. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a chip G2 in which one end in the width direction is missing. Such shape defects of the cut surfaces ga, Ga occur due to the ears being relatively thick. Conversely, in the glass sheet g shown in FIG. 5b, a shape defect occurs on the upper cut surface ga due to a chip g2 in which one end in the width direction is missing. Due to this, a shape defect occurs on the lower cut surface Ga of the glass ribbon G shown in the same figure due to a horn G1 in which one end in the width direction protrudes downward. Such shape defects of the cut surfaces ga, Ga also occur due to the ears being relatively thick.

[0069] In the glass plate g shown in FIG. 6, a shape defect exhibiting a wavy shape occurs over the entire upper cut surface ga. Due to this, a shape defect exhibiting a wavy shape also occurs over the entire lower cut surface Ga of the glass ribbon G shown in the same figure. Such shape defects occur when cracks deviate from the scribe line and propagate. In addition, shape defects caused by cracks deviating from the scribe line and propagating may occur in cases where part of the cut surface ga exhibits a wavy shape, or part or all of the cut surface ga exhibits a bow shape.

[0070] In the examples shown in Figs. 4a to 6, the concaves and convexes of shape defects in the glass plate g and the concaves and convexes of shape defects in the glass ribbon G are in an opposite relationship at the same position in the width direction, but this relationship is not necessarily required.

[0071] The glass plate g shown in Fig. 7 has one partial break g3 originating from the upper cut surface ga. The partial break g3 is, for example, 3 to 500 mm deep and 10 to 2000 mm wide, and is larger than the above-mentioned chip g2. The number of partial breaks g3 may be multiple. Such partial break g3 occurs when a part of the glass plate g (the periphery of the upper cut surface ga or the middle part in the width direction) is broken during cutting.

[0072] In the glass sheet g shown in FIG. 8, a crack g4 occurs at one location due to a vertical crack G4 in the glass ribbon G. This crack g4 occurs due to a vertical crack G4 in the glass ribbon G caused by the crack propagating in the up-down direction. The vertical crack G4 may lead to damage to the entire glass ribbon G over time. Therefore, the crack g4 in the glass sheet g caused by the vertical crack G4 in the glass ribbon G tends to become larger in the subsequent glass sheets g, and ultimately, it may become impossible to cut out the glass sheet g from the glass ribbon G.

[0073] 9 to 16 are thermal images F1 to F5 showing the temperature distribution measured by the thermograph 31, and the measurement objects g and Gt having defects are shown in these thermal images F1 to F5. For convenience, FIGS. 9 to 14 show only the main parts of the measured thermal images. Here, the temperature of the measurement objects g and Gt is, for example, less than 100°C, and preferably less than 80°C. In addition, the temperature of the measurement objects g and Gt is higher than the temperature of the surrounding spatial region Z. Therefore, in the thermal images F1 to F5, the glass sheet g and the glass ribbon G are depicted in a light color, and the surrounding spatial region Z is depicted in a dark color.

[0074] Thermal images F1 to F3 shown in Figures 9 to 11 show the shapes of the cut surfaces g and Ga of the measurement objects g and G. The detection unit 32 obtains the distribution of the height positions of the cut surfaces g and Ga from these thermal images F1 to F3, and detects whether or not there is a shape defect in the cut surfaces g and Ga based on the height (here, the height difference). A specific method for this will be described below.

[0075] The thermal image F1 shown in FIG. 9 shows the measurement objects g and Gt having the defects shown in FIG. 4a. Here, a method for the detection unit 32 to detect the shape defect caused by the horn g1 generated on the upper cut surface ga of the glass plate g from the thermal image F1 will be described. First, in the region (relatively bright region) on the thermal image F1 where the glass plate g is drawn, a basic straight line K1 parallel to the straight line K0 is set at a position separated by a predetermined distance from the straight line K0 where the scribe line S was formed. Next, the maximum and minimum values ​​of the distance from the straight line K1 to the upper contour line of the region where the glass plate g is drawn are obtained. In the illustrated example, the distance (maximum value) Ma from the straight line K1 to the top gx of the horn g1 and the distance (minimum value) Mi from the straight line K1 to the straight line K0 are obtained. Then, the difference ΔM between the maximum value Ma and the minimum value Mi is calculated, and the detection unit 32 detects the shape defect generated on the upper cut surface ga of the glass plate g based on the difference ΔM and a threshold value. Specifically, when the difference ΔM is equal to or less than the threshold, the detection unit 32 determines that there is no shape defect, and when the difference ΔM exceeds the threshold, the detection unit 32 detects that there is a shape defect. Here, since the difference ΔM exceeds the threshold, the detection unit 32 detects that there is a shape defect in the glass sheet g. Note that even when a horn g1 occurs on the upper cut surface ga of the glass sheet g in the manner shown in FIG. 5a, the detection unit 32 detects the presence or absence of a shape defect occurring in the glass sheet g in the same manner as described here.

[0076] The thermal image F2 shown in FIG. 10 shows the measurement objects g and Gt having the defects shown in FIG. 4b. Here, a method for the detection unit 32 to detect a shape defect caused by a chip g2 occurring on the upper cut surface ga of the glass plate g from the thermal image F2 will be described. For this thermal image F2, a straight line K1 is set at the same position as above, and the maximum and minimum values ​​of the distance from this straight line K1 to the upper contour line of the area in which the glass plate g is drawn are obtained. In the illustrated example, the distance (minimum value) Mi from the straight line K1 to the lowest part gy of the chip g2 and the distance (maximum value) Ma from the straight line K1 to the straight line K0 are obtained. Then, when the difference ΔM between the maximum value Ma and the minimum value Mi is equal to or less than a threshold value, the detection unit 32 determines that the shape is not defective, and when the difference ΔM exceeds the threshold value, it detects that the shape is defective. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that the shape is defective in the glass plate g. Incidentally, even when a chip g2 occurs on the upper cut surface ga of the glass plate g in the manner shown in FIG. 5b, the detection unit 32 detects whether or not the shape is defective in the same manner as described here.

[0077] The thermal image F3 shown in FIG. 11 shows the measurement objects g and Gt having defects as shown in FIG. 6. Here, a method for the detection unit 32 to detect a shape defect due to a wavy shape generated on the upper cut surface ga of the glass plate g from the thermal image F3 will be described. For this 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 this straight line K1 to the upper contour line of the area in which the glass plate g is drawn are obtained. In the illustrated example, the distance (maximum value) Ma from the straight line K1 to the top gz of the highest mountain among the multiple mountains, and the distance (minimum value) Mi from the straight line K1 to the bottom gZ of the lowest valley among the multiple valleys are obtained. Then, when the difference ΔM between the maximum value Ma and the minimum value Mi is equal to or less than a threshold value, the detection unit 32 determines that the shape is not defective, and when the difference ΔM exceeds the threshold value, it detects that the shape is defective. Here, since the difference ΔM exceeds the threshold value, the detection unit 32 detects that the shape is defective in the glass plate g.

[0078] The shape defect caused by the chip G2 occurring on the lower cut surface Ga of the glass ribbon G in the thermal image F1 shown in FIG. 9 can be detected by substantially the same method as the shape defect caused by the chip g2 on the thermal image F2 shown in FIG. 10. The shape defect caused by the horn G1 occurring on the lower cut surface Ga of the glass ribbon G in the thermal image F2 shown in FIG. 10 can be detected by substantially the same method as the shape defect caused by the horn g1 on the thermal image F1 shown in FIG. 9. The shape defect caused by the wave shape occurring on the lower cut surface Ga of the glass ribbon G in the thermal image F3 shown in FIG. 11 can be detected by substantially the same method as the shape defect caused by the wave shape of the glass sheet g on the thermal image F3 shown in the same figure. The substantially same method here means that the method itself is the same, except that the up-down relationship is reversed.

[0079] In this case, when the detection unit 32 detects that the glass sheet g has a shape defect from the thermal images F1 to F3 illustrated in Figs. 9 to 11, the gripping operation by the chuck 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 collected. Here, the glass sheet g after cutting is often conveyed to a subsequent process by gripping its upper part. Therefore, if the glass sheet g having a shape defect on the upper cut surface ga is discarded, it is possible to prevent the glass sheet g from being damaged when being conveyed by gripping its upper part, and the associated contamination of the production line. In addition, since the shape defect on the upper cut surface ga of the glass sheet g is likely to occur due to wear and tear of the wheel cutter 23, it is preferable to replace the wheel cutter 23 when the detection unit 32 detects that the shape defect has occurred. In this way, it is possible to prevent the subsequent glass sheets g from having a shape defect.

[0080] 9 to 11, 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 is obtained from the thermal image, the height of the point at which the height position is the maximum on the contour line is set as the maximum value Ma, and the height of the point at which the height position is the minimum is set as the minimum value Mi, and the difference ΔM may be obtained from them.

[0081] Figures 12 to 14 respectively illustrate other methods for detecting a shape defect of the glass sheet g from the thermal images F1 to F3 shown in Figures 9 to 11. These other methods also involve the detection unit 32 obtaining a distribution of height positions of the cut surfaces ga, Ga from the thermal images F1 to F3, and detecting a shape defect of the cut surfaces ga, Ga based on the height distribution.

[0082] In the method illustrated in FIG. 12, first, on the thermal image F1, measurement lines L1 and L2 are drawn above and below the line L0 on which the regular cutting line of the glass plate g, that is, the scribe line S, was formed. These two measurement lines L1 and L2 are parallel to the line L0 and are spaced the same distance from the line L0. Then, it is measured whether there is a place on the upper measurement line L1 where the brightness is higher than a preset value, that is, whether there is a place where the temperature is higher than a preset temperature. It is also measured whether there is a place on the lower measurement line L2 where the brightness is higher than a preset value (whether there is a place where the temperature is higher than a preset value). In this case, the range in which the brightness (temperature) is measured is the entire range in the width direction of the glass plate g on the measurement lines L1 and L2. In this thermal image F1, there is one location 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. By recognizing this state, the detection unit 32 detects that a shape defect has occurred in the glass sheet g. Note that the detection unit 32 also detects whether or not a horn g1 generated on the upper cut surface ga of the glass sheet g in the manner shown in FIG. 5a is a shape defect in the same manner as described here.

[0083] In the method illustrated in FIG. 13, similarly to the above-mentioned case, measurement lines L1 and L2 are drawn above and below the line L0 on the thermal image F2, and the brightness (temperature) on the upper measurement line L1 and the brightness (temperature) on the lower measurement line L2 are measured. In this 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 one location on the lower measurement line L2 where the brightness (temperature) is lower than the set value. By recognizing such a state, the detection unit 32 detects that a shape defect has occurred in the glass sheet g. In addition, the detection unit 32 detects whether or not a chip g2 generated on the upper cut surface ga of the glass sheet g in the manner shown in FIG. 5b is a shape defect in the same manner as described here.

[0084] 14, in the same manner as described above, measurement lines L1, L2 are drawn above and below the line L0 on 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 this thermal image F3, there are multiple points (two in the illustrated example) 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. By recognizing such a state, the detection unit 32 detects that a shape defect has occurred in the glass sheet g.

[0085] 15 and 16 show thermal images F4 and F5 in which the entire area of ​​the glass sheet g and the cut-side end Gt of the glass ribbon G are projected. From these thermal images F4 and F5, the detection unit 32 obtains the areas of the measurement objects g and Gt, and detects defects occurring in the measurement objects g and G based on the areas and a threshold value. A specific method for this will be described below.

[0086] The thermal image F4 shown in FIG. 15 shows the measurement targets g and Gt having the defects shown in FIG. 7. Here, a method for the detection unit 32 to detect the partial damage g3 that has occurred in the glass plate g from the thermal image F4 will be described. First, the area of ​​the glass plate g is obtained from the number of pixels on the thermal image F4. In this case, the area of ​​the glass plate g that is held by the chuck 27 may have a lower temperature than the area that is not held, and may be depicted in a dark color similar to that of the spatial area Z. In this case, the area of ​​the area where the main surface of the glass plate g is exposed is obtained. In addition, when the area of ​​the glass plate g that is held by the chuck 27 and the area that is not held have the same temperature and are both depicted in a light color, the area of ​​the entire area of ​​the glass plate g is obtained. If this area exceeds a first threshold, the detection unit 32 determines that the partial damage g3 is not present, and if this area is equal to or less than the first threshold and exceeds a second threshold described later, the detection unit 32 detects the partial damage g3. The first threshold value is, for example, 90% to 99% of the area of ​​the glass plate g in a state where no defects have occurred (the area corresponding to the above region). Here, since the above area is equal to or smaller than the first threshold value and exceeds the second threshold value, the detection unit 32 detects that partial damage g3 has occurred in the glass plate g.

[0087] In this case, when the detection unit 32 detects that the glass sheet g has a partial break g3 from the thermal image F4 illustrated in FIG. 15, the gripping action by the chuck 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 collected. This makes it difficult for the glass sheet g having the partial break g3 to be mistakenly transported to a subsequent process and subjected to subsequent processing. In addition, since the partial break g3 of the glass sheet g is likely to occur when the warp of the glass ribbon G is large, it is preferable to take measures to reduce the warp of the glass ribbon G when the detection unit 32 detects that the partial break g3 has occurred. In this way, the occurrence of the partial break g3 in the subsequent glass sheet g can be suppressed.

[0088] The thermal image F5 shown in FIG. 16 shows the measurement targets g and Gt having defects in the manner shown in FIG. 8. Here, a method for the detection unit 32 to detect the cracks and damage g4 associated with the vertical cracks G4 of the glass ribbon G from the thermal image F5 will be described. First, the area of ​​the glass sheet g is obtained from the number of pixels on the thermal image F5. The relationship between the area of ​​the glass sheet g and the chuck 27 is the same as that described above. If the area exceeds the second threshold, the detection unit 32 determines that the cracks and damage g4 are not present, and if the area is equal to or less than the second threshold, the detection unit 32 detects the cracks and damage g4. The second threshold is, for example, 30% to 50% of the area of ​​the glass sheet g in a state where no defects are present (the area corresponding to the above region). Here, since the above area is equal to or less than the second threshold, the detection unit 32 detects that the cracks and damage g4 are present in the glass sheet g. In this case, as described above, the crack or breakage g4 of the glass sheet g occurs in conjunction with the vertical crack G4 of the glass ribbon G. Therefore, when the detection unit 32 detects that the crack or breakage g4 has occurred in the glass sheet g, the detection unit 32 also detects that the vertical crack G4 has occurred in the glass ribbon G. In other words, the occurrence of the crack or breakage g4 of the glass sheet g is regarded as the occurrence of the vertical crack G4 of the glass ribbon G. The second threshold value is set as a value that satisfies such circumstances.

[0089] In this case, when it is detected from the thermal image F5 illustrated in Fig. 16 that a crack or breakage g4 has occurred in the glass sheet g, it is determined that a vertical crack G4 has occurred in the glass ribbon G, and the cutting device 2 moves to a retracted position based on a control signal from the control unit 33. This retracted position is a position where glass fragments and glass powder from the glass ribbon G do not fall onto the cutting device 2. At the retracted position, glass fragments and the like adhering to the cutting device 2 are removed by cleaning. This makes it possible to prevent a situation in which the glass ribbon G or the glass sheet g is damaged by glass fragments and glass powder remaining in the cutting device 2 when the forming of the glass ribbon G is resumed and the cutting device 2 is returned to its original position.

[0090] This glass sheet 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 recognize the type of defect, it may recognize the defect by type. In this case, it is possible to perform post-processing by classifying the defects by type.

[0091] According to the glass sheet manufacturing apparatus having the above-mentioned configuration, defects occurring in the measurement objects g, Gt can be detected with high accuracy, but in order to further improve the accuracy of defect detection, the following configuration may be adopted.

[0092] In the first configuration, as shown in Fig. 17, multiple thermographs 31 (three in the illustrated example) are installed along the width direction. These thermographs 31 are arranged at equal intervals in the width direction and installed at the same height position. This height position is the same as the height position when one thermograph 31 is installed as described above. Furthermore, the separation distance and separation pattern of these thermographs 31 from the measurement targets Gt, g are also the same as the separation distance and separation pattern when one thermograph 31 is installed as described above.

[0093] In the measurement of the temperature distribution by these thermographs 31, multiple thermal images (three in this embodiment) are obtained. More specifically, as shown in FIG. 18, the regions 35 in which the multiple thermographs 31 can measure the measurement objects g and Gt are aligned in a line in the width direction. These regions 35 overlap with each other (the overlapping portion is indicated by the reference symbol 35x) and cover the entire width direction region of the measurement objects g and Gt. Therefore, multiple thermal images are also obtained by capturing the measurement objects g and Gt in the same manner as the measurable regions 35 and 35x. That is, the multiple thermal images are obtained by capturing the entire width direction region of the measurement objects g and Gt, in which adjacent thermal images partially overlap. This allows defects occurring in the measurement objects g and Gt to be detected without omission by the thermal images captured by the multiple thermographs 31. If a defect in the cut-side end Gt of the glass sheet g or the glass ribbon G is detected by any one of the thermal images of the multiple thermographs 31, the cut-side end Gt of the glass sheet g or the glass ribbon G is determined to be defective. On the other hand, if a defect in 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 determined to be not defective. In this case, an anti-reflection member (not shown) is attached or otherwise disposed in front of each thermograph 31. If this anti-reflection member is not disposed, the reflected light of lighting or the like may cause a decrease in detection accuracy when detecting defects using each thermograph 31. According to the configuration here, the presence of the anti-reflection member makes it difficult to be adversely affected by the reflected light of lighting or the like.

[0094] In a second configuration, as shown in Fig. 19, each thermograph 31 is installed so as to measure the temperature distribution of the measurement objects g, Gt from obliquely below. In the illustrated example, the lower end Gt of the glass ribbon G is omitted (the same applies to Figs. 20 to 23 described later). In this case, the angle α between the horizontal direction and the direction C in which each thermograph 31 is oriented toward the surface of the glass plate g is 3° to 80° (preferably, the lower limit is 30° and the upper limit is 60°).

[0095] According to this second configuration, when the glass sheet 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 with respect to the vertical direction), the following advantages are obtained. That is, as shown in Fig. 20, an area 35 in which the glass sheet g can be measured when the measurement is performed by the thermograph 31 from obliquely below is longer in the vertical direction than an area 35a in which the glass sheet g can be measured when the measurement is performed along the horizontal direction. Therefore, defects occurring in the glass sheet g can be detected in a wide measurement area.

[0096] Furthermore, this second configuration also provides the following advantage. That is, when the measurement using the thermograph 31 is performed horizontally or obliquely from above, the thermograph 31 needs to be installed in a relatively higher position (for example, in the area indicated by the symbol H in FIG. 19) than when the measurement is performed obliquely from below. In such a case, there is a risk that the thermograph 31 will interfere with the scribe line forming device 21 or other devices not shown, reducing the degree of freedom in the installation space for the thermograph 31. In this second configuration, the thermograph 31 can be installed in a relatively lower position as shown in FIG. 19, compared to when the measurement is performed horizontally or obliquely from above. This makes it less likely that the thermograph 31 will interfere with the scribe line forming device 21 or other devices not shown, increasing the degree of freedom in the installation space for the thermograph 31.

[0097] As a third configuration, as shown in Fig. 21, the direction C of each thermograph 31 facing the surface of the glass sheet g can be adjusted in the vertical direction. More specifically, each thermograph 31 can be rotated in the DD direction around a fulcrum 31s on its central axis. Therefore, by changing the direction C of each thermograph 31, the area in which the glass sheet g can be measured varies along the vertical direction. In this case, the direction C of each thermograph 31 may be adjusted simultaneously by linking all of the thermographs 31 together, or may be adjusted individually at different times.

[0098] According to the third configuration, it is possible to appropriately deal with adverse effects that may occur when the size, thickness, type, etc. of the glass ribbon G formed and transported in the forming zone 11 are changed, or when the glass sheet g shakes even if no change is made. That is, when such a change or shake occurs, the position of the glass sheet g after cutting may shift in the vertical direction. When such a position shift occurs, not only the detection accuracy of defects occurring in the glass sheet g decreases, but in some cases, a part or the whole of the glass sheet g may deviate from the area that can be measured by the thermograph 31, making it impossible to detect the defects. According to the configuration here, by adjusting the orientation C of the thermograph 31 in the vertical direction, the area that can be measured by the thermograph 31 can be shifted in response to the vertical shift of the glass sheet g. As a result, the area that can be measured by the thermograph 31 is appropriately corrected, and the detection of defects is further improved in accuracy.

[0099] As a fourth configuration, as shown in Fig. 22 (plan view), the direction C of each thermograph 31 facing the surface of the glass sheet g can be adjusted in the width direction. More specifically, each thermograph 31 can be rotated in the E-E direction around a fulcrum 31t on its central axis. Therefore, by changing the direction C of the thermograph 31, the area in which the glass sheet g can be measured varies along the width direction. In this case, the direction C of each thermograph 31 may be adjusted simultaneously by linking all of the thermographs 31 together, or may be adjusted individually at different times.

[0100] According to this fourth configuration, even if the glass plate g after cutting shifts in the width direction due to changes or vibrations similar to those described above, the area in which the glass plate g can be measured by the thermograph 31 can be appropriately corrected by adjusting the orientation of the thermograph 31 in the width direction.

[0101] As a fifth configuration, as shown in Fig. 23, the position of each thermograph 31 in the vertical direction can be adjusted. More specifically, each thermograph 31 can be translated in the vertical direction (FF direction). Therefore, by changing the vertical position of the thermograph 31, the area in which the glass plate g can be measured varies along the vertical direction. In this case, the vertical position of each thermograph 31 may be adjusted simultaneously by linking all of the thermographs 31 together, or may be adjusted individually at different times.

[0102] According to this fifth configuration, even if the glass plate g after cutting shifts in the vertical direction due to changes or vibrations similar to those described above, the area in which the glass plate g can be measured by the thermograph 31 can be appropriately corrected by adjusting the vertical position of the thermograph 31.

[0103] With regard to the third, fourth and fifth configurations described above, it is possible to have only one of these configurations, or to have two configurations arbitrarily selected from these configurations, or even to have three of these configurations.

[0104] As a sixth configuration, an initial setting and a more detailed image analysis for detecting defects are performed on the thermal image obtained by the measurement using the thermograph 31. FIG. 24 shows a thermal image Fw taken by the thermograph 31 installed at the end (left end) in the width direction, and FIG. 25 shows a thermal image Fx taken by the thermograph 31 installed at a portion other than both ends in the width direction. As an initial setting, a defect inspection area 36 is set on each of the thermal images Fw and Fx shown in these figures, the defect inspection area 36 covering the upper end (end on the cutting side) gt of the glass sheet g and the space Z1 above it. The defect inspection areas 36 set on all of the multiple (three) thermal images Fw and Fx partially overlap with adjacent defect inspection areas 36, and cover the entire width direction area of ​​the upper end gt of the glass sheet g.

[0105] First, a method of setting the defect inspection area 36 on the thermal image Fw shown in FIG. 24 will be described. First, the upper edge ga1 (its height position) of the glass plate g is detected on the thermal image Fw, and the detected upper edge ga1 is set as the origin position in the vertical direction. Here, detecting the upper edge ga1 of the glass plate g means the following. That is, when the upper cut surface ga of the glass plate g appears as a straight line in the horizontal direction, the cut surface ga is detected as the upper edge ga1. On the other hand, when the upper cut surface ga of the glass plate g appears as a wave shape or a shape inclined with respect to the horizontal direction, for example, the highest or lowest part of the cut surface ga, or the vertical center between the highest and lowest parts, is detected as the upper edge ga1. In this case, when it is clear that the height difference such as the wave shape or the inclined shape is extremely large, the detection unit 32 can detect it as an obvious defect, so the setting here is not performed.

[0106] In addition, in this thermal image Fw, a boundary gf between an edge ge formed at the end of the width direction of the glass plate g and a part gc closer to the center in the width direction than the edge ge appears, so the boundary gf is detected and the boundary gf is set as the origin position in the width direction. The origin position in the width direction may be the outer edge gf1 in the width direction of the edge ge. Then, based on the origin position ga1 in the vertical direction and the origin position gf in the width direction, a rectangular inspection frame 37 elongated in the width direction is drawn superimposed on the thermal image Fw. As a result, the inner area surrounded by the inspection frame 37 is set as the defective inspection area 36. In the thermal image Fw according to this embodiment, the defective inspection area 36 is positioned so that the origin position ga1 in the vertical direction exists in the vertical center. In addition, one end (left end) in the width direction of the defective inspection area 36 is positioned to the left of the origin position gf in the width direction based on the origin position gf. Furthermore, the other end (right end) in the width direction of the defect inspection area 36 is positioned so as to be present at the right end of the thermal image Fw. Therefore, the defect inspection area 36 here is one area N extracted by one inspection frame 37 so that the left end portion of the upper end gt of the glass plate g becomes the inspection target. The same initial settings as above are also performed for the thermal image Fw captured by the thermograph 31 installed at the right end in the width direction.

[0107] According to such a method, even if the vertical and widthwise positions of the glass plate g depicted in the thermal image Fw are not uniformly determined, the vertical and widthwise positions of the defect inspection area 36 relative to the glass plate g on the thermal image Fw are uniformly determined. This makes it difficult for erroneous detections to occur when detecting defects occurring in the glass plate g by image analysis in the defect inspection area 36 (described later), and makes it possible to more reliably improve the accuracy of defect detection.

[0108] Next, a method of setting the defect inspection area 36 on the thermal image Fx shown in FIG. 25 will be described. In this case, since the width direction end of the glass plate g does not appear on the thermal image Fx, there is no need to detect the origin position in the width direction. Therefore, both ends of the defect inspection area 36 in the width direction are aligned so as to be present at both ends of the thermal image Fx in the width direction. Then, also on this thermal image Fx, the origin position ga1 in the up-down direction is determined, and the defect inspection area 36 is set by the inspection frame 37. Therefore, the defect inspection area 36 here is one area M extracted by one inspection frame 37 so that the center part in the width direction of the upper end gt of the glass plate g becomes the inspection target. The method executed at this time is the same as the method based on FIG. 24 described above. Therefore, according to this method, if the one based on the origin position in the width direction is excluded, the same action and effect as the method based on FIG. 24 described above can be obtained.

[0109] FIG. 26 illustrates one form of a part of the region N(M) extracted by the inspection frame 37. In this part of the region N(M), a shape defect due to a corrugated shape occurs on the upper cut surface ga of the glass sheet g. The vertical origin position ga1 shown in the figure is located in the vertical center between the lowest and highest points of the corrugated shape (including the corrugated shapes of other regions). In addition, the corrugated shape is exaggerated in the figure. This part of the region N(M) is composed of a plurality of unit pixel groups Pk partitioned vertically and horizontally in a lattice shape. One unit pixel group Pk is a collection of a plurality of pixels. In this part of the region N(M), the brightness of the group of unit pixel groups Pk arranged horizontally at the bottom (group marked with a circle in the figure) is set as a reference brightness corresponding to the reference temperature. The difference in brightness from this reference brightness identifies the boundary between the upper end gt of the glass sheet g and the space Z1 above it. Under such settings, the 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 among the unit pixel groups Pk present above the group of unit pixel groups Pk marked with circles in the figure. In the figure, the unit pixel groups Pk including the above-mentioned boundaries extracted here are marked with crosses. Furthermore, among the unit pixel groups Pk extracted here, the number of unit pixel groups Pk corresponding to the height difference from the bottom to the top (i.e., the number of stages with cross marks when a horizontal row is considered as one stage) is obtained. Then, if the obtained number is equal to or greater than a preset number, the detection unit 32 detects the shape defect as being due to a corrugated shape, and if the obtained number is less than the preset number, the detection unit 32 determines that the shape defect is not due to a corrugated shape. In the illustrated example, the obtained number is four and the preset number is three, so the detection unit 32 detects that a shape defect due to a corrugated shape has occurred. In addition, such an image analysis method can also be applied in a similar manner when the upper cut surface ga of the glass plate g has a shape defect due to the above-mentioned horn g1 or chip g2.

[0110] According to such an image analysis method, the boundary is determined based on the origin position ga1 in the vertical direction (including the origin position gf in the width direction in some cases) at a certain position on the glass plate g as the reference brightness, so that it is possible to prevent variations and mistakes in determining the boundary each time an inspection is performed. Moreover, since the occurrence of defects can be detected simply by finding the number of pixels corresponding to the height difference of the boundary determined by the brightness difference from the reference brightness, the ease and accuracy of image analysis are ensured.

[0111] FIG. 27 illustrates another example of a part of the region N(M) extracted by the inspection frame 37. In this part of the region N(M), a defect due to partial damage g3 occurs on the upper cut surface ga of the glass plate g. Here, in this part of the region N(M), the number of unit pixel groups Pk partitioned vertically and horizontally in a lattice shape is greater than in the above case. Therefore, one unit pixel group Pk has fewer pixels than in the above case. Also, in this part of the region N(M), the origin position ga1 in the height direction exists at the boundary between the upper end gt of the glass plate g and the space Z1 above it (excluding the boundary with the partial damage 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 partial damage g3) and the space Z1 above it is identified by the brightness difference from the reference brightness, and the difference between the upper end gt and the space Z1 is also identified. Under such settings, 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, g3b of the partial damage g3 and the virtual straight line ga11 is calculated from the number of unit pixel groups Pk (or pixels Pk). If the calculated area value is equal to or greater than a preset area value (the area value of the missing part of the glass plate g), the detection unit 32 detects the partial damage g3, and if the calculated area value is less than the preset area value, the detection unit 32 determines that the partial damage g3 is not present. In the illustrated example, since the calculated area value is equal to or greater than the preset area value, the detection unit 32 detects that the partial damage g3 has occurred.

[0112] Alternatively, the following method may be adopted. That is, the area of ​​the glass sheet g excluding the above-mentioned region Zx (the area of ​​the glass sheet g depicted in the relevant portion of the region N(M)) may be obtained from the number of unit pixel groups Pk (or pixels Pk). In this case, a value based on the area of ​​the glass sheet g when no defects occur in the glass sheet g (for example, the above-mentioned first threshold value) is set in advance. In this way, when the obtained area value exceeds the predetermined area value, the detection unit 32 determines that the partial damage g3 is not caused, and when the obtained area value is equal to or less than the predetermined area value, the detection unit 32 detects the partial damage g3. Note that the image analysis method based on FIG. 27 can be similarly applied when a shape defect occurs on the upper cut surface ga of the glass sheet g due to the above-mentioned horn g1 or chip g2, and further when a crack or damage g4 occurs due to the above-mentioned vertical crack in the glass ribbon G. In particular, when detecting cracks or damage g3 associated with vertical cracks in the glass ribbon G, at least one of the multiple thermal images captured by the multiple thermographs 31 may depict a state in which the glass plate g is completely absent, and therefore, it may be possible to detect the cracks or damage g3 without calculating the area value from the number of pixels.

[0113] According to such an image analysis method, a certain position on the glass plate g is set as a reference brightness based on the origin position ga1 in the vertical direction (including the origin position gf in the width direction in some cases), and the boundary and the difference between the upper end gt and the upper space Z1 are discriminated. Therefore, it is possible to prevent variations and mistakes in discriminating the boundary and the above-mentioned difference each time an inspection is performed. Moreover, since the occurrence of a defect can be detected simply by calculating the area value from the number of pixels within the region N (M) whose position has been corrected based on the above-mentioned origin position ga1 (gf), the ease and accuracy of image analysis are ensured.

[0114] Next, a method for producing a glass sheet using the glass sheet producing apparatus having the above-mentioned configuration will be described.

[0115] The glass sheet manufacturing method according to this embodiment includes a forming step, a transporting step, a cutting step, and a detecting step.

[0116] The forming step is a step of forming a glass ribbon G in the forming zone 11 .

[0117] The conveying step is a step of conveying the formed glass ribbon G by the roller pair R of the conveying device 14. The conveying step includes a heat treatment step and a cooling step.

[0118] The heat treatment step is a step of carrying out a heat treatment on the glass ribbon G that has been subjected to the forming step in the heat treatment zone 12 while transporting the glass ribbon G.

[0119] The cooling step is a step in which the glass ribbon G that has been subjected to the heat treatment step is cooled while being transported in the cooling zone 13.

[0120] The cutting step is a step in which the glass ribbon G that has been subjected to the cooling step is conveyed and cut in the width direction by a cutting device 2 to obtain glass sheets g.

[0121] The detection process is a process in which the temperature distribution of the measurement objects consisting of the cut side end Gt of the glass ribbon G and the glass plate g is measured using a thermograph 31, and based on the measurement results, it is detected whether or not defects have occurred in the measurement objects Gt, g, as already described in detail.

[0122] The above describes the glass sheet manufacturing apparatus and the manufacturing method thereof according to an embodiment of the present invention. However, the embodiment of the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

[0123] In the above embodiment, shape defects of the cut surface of the object to be measured are detected based on the height distribution of the cut surface obtained from a thermal image showing the temperature distribution of the thermograph, but shape defects of the cut surface of the object to be measured may also be detected by other image analysis methods.

[0124] In the above embodiment, partial 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 a threshold value, but partial breakage and vertical cracks may be detected by other image analysis. In addition, the area of ​​the glass sheet g may be calculated as the entire area of ​​the glass sheet g, or may be calculated as a part of the area of ​​the glass sheet g. For example, the area of ​​the middle part of the glass sheet g gripped by the chuck 27 excluding both ends may be calculated, and partial 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 a threshold value.

[0125] In the above embodiment, the temperature of the measurement objects Gt, g was measured by measuring the temperature distribution using a thermograph 31, but instead, the temperature distribution of the measurement objects Gt, g may be measured using a linear sensor thermometer capable of measuring temperature in a straight line.

[0126] In the above embodiment, the measurement object includes both the cut-side end portion Gt of the glass ribbon G and the glass sheet g, but only one of these two may be the measurement object.

[0127] In the above embodiment, defects such as horns, chips, corrugations, partial breakage, and breakage due to vertical cracks are detected individually for each measurement object, but there are cases where multiple types of defects occur simultaneously in a single measurement object. In such cases, multiple types of defects (the presence or absence of those defects) may be detected for a single measurement object.

[0128] In the above embodiment, the glass ribbon G is formed by the overflow downdraw method. However, it may be formed by other downdraw methods such as a slot downdraw method or a redraw method, or a float method.

[0129] In the above embodiment, the glass ribbon G is cut by folding along the scribe lines S, but other methods such as laser cleaving and laser melting may be used for cutting. Even when such a method is adopted, vibrations and impacts are generated when the glass sheet g is separated from the glass ribbon G, which may cause shaking of the glass ribbon G and the glass sheet g, but the present invention is less susceptible to adverse effects of such shaking.

[0130] In the above embodiment, the thermal images shown in Figs. 9 to 14 are parts of a thermal image obtained by one thermograph, but these thermal images may be the entire thermal images of one of the thermal images obtained by a plurality of thermographs (see Fig. 17). In this case, the glass ribbon may not be depicted in the thermal image as shown in Figs. 26 and 27 when detecting a defect. In addition, in the thermal images shown in Figs. 15 and 16, the entire glass sheet is depicted, but only the upper part (for example, the upper end) of the glass sheet may be depicted, and in this case, only a part of the glass sheet in the width direction (only a part of the glass ribbon in the width direction) may be depicted. In such a case, the glass ribbon may not be depicted as shown in Figs. 26 and 27 when detecting a defect. [Explanation of symbols]

[0131] 1 Processing equipment 2 Cutting device 3. Detection Device 11 Forming Zone 14 Conveyor device 22 Cutting device 31 Thermography 32 Detection unit 36 Defective inspection area F1 Thermal Image F2 Thermal Image F3 Thermal Image F4 Thermal Image F5 Thermal Imaging Fw Thermal Image Fx Thermal Image G Glass ribbon Gt Cut end of glass ribbon g. Glass plate G1 Horn g1 Horn G2 chipped g2 chipped G3 partially damaged g3 partially damaged G4 Vertical Crack g4 Vertical crack Lower cut surface of Ga glass ribbon ga Upper cut surface of glass plate ga1: Origin position in the vertical direction (upper edge of the glass plate) Gm Molten Glass Z1 Space above the glass plate

Claims

1. A glass sheet manufacturing method comprising: a forming step of forming a glass ribbon in a forming zone; a conveying step of conveying the glass ribbon along a longitudinal direction; and a cutting step of cutting the glass ribbon along a width direction to cut out a glass sheet, A detection process is provided in which a cut side end of the glass ribbon after cutting in the cutting process, a glass sheet, or any one of them is used as a measurement object, a temperature is measured for the measurement object, and a defect occurring in the measurement object is detected based on the measurement result, The method for manufacturing a glass plate, wherein in the detection step, the temperature of the measurement object is measured by measuring a temperature distribution by thermography.

2. 2. The method for manufacturing a glass sheet according to claim 1, wherein in the cutting step, the glass sheet is cut out by bending and breaking the glass ribbon along scribe lines extending in a width direction of the glass ribbon.

3. 3. The method for manufacturing a glass sheet according to claim 1, wherein in the forming step, the glass ribbon is formed by a down-draw method.

4. 4. The method for manufacturing a glass sheet according to claim 3, wherein the defects detected in the detection step include a shape defect of an upper cut surface of the glass sheet after cutting in the cutting step.

5. 5. The method for manufacturing a glass plate according to claim 4, further comprising the steps of: determining a distribution of height positions of the upper cut surface from a temperature distribution in the glass plate; and detecting a shape defect of the upper cut surface based on the distribution of height positions.

6. 6. The method for producing a glass plate according to claim 4, further comprising the step of discarding the glass plate when a defective shape of the upper cut surface is detected.

7. 7. The method for manufacturing a glass sheet according to claim 3, wherein the defects detected in the detection step include partial breakage of the glass sheet after cutting in the cutting step.

8. The method for manufacturing a glass sheet according to claim 7, further comprising the steps of: determining an area of ​​at least a portion of the glass sheet from a temperature distribution in the glass sheet; and detecting the partial breakage based on the area and a first threshold value.

9. 9. The method for manufacturing a glass plate according to claim 7, further comprising the step of discarding the glass plate when the partial breakage is detected.

10. The glass plate manufacturing method according to any one of claims 3 to 9, characterized in that the defects detected in the detection step include cracks or breakage of the glass plate due to vertical cracks in the glass ribbon after cutting in the cutting step.

11. The method for manufacturing a glass sheet according to claim 10, further comprising the steps of: determining an area of ​​at least a portion of the glass sheet from a temperature distribution in the glass sheet; and detecting the crack or breakage based on the area and a second threshold value.

12. The glass plate manufacturing method according to claim 10 or 11, characterized in that, when the crack or breakage is detected, it is determined that a vertical crack has occurred in the glass ribbon, and a cutting device used to perform the cutting step is withdrawn.

13. 13. The method for manufacturing a glass plate according to claim 3, wherein the thermography measures the temperature distribution of the measurement object from obliquely below.

14. 14. The method for manufacturing a glass plate according to claim 3, wherein the direction of the thermograph directed toward the surface of the object to be measured is adjustable in the vertical direction.

15. 15. The method for manufacturing a glass plate according to claim 3, wherein the direction in which the thermograph is directed toward the surface of the object to be measured is adjustable in the width direction.

16. 16. The method for manufacturing a glass plate according to claim 3, wherein the position of the thermograph is adjustable in the vertical direction.

17. The method for manufacturing a glass plate according to any one of claims 3 to 16, characterized in that a height position of an upper edge of the glass plate after cutting is detected on a thermal image obtained by measuring the temperature distribution by the thermograph, and this detected height position is used as an origin position in the vertical direction to set a defect inspection area covering the upper end of the glass plate and the space above it, and defects occurring in the glass plate are detected by image analysis within the defect inspection area.

18. A glass sheet manufacturing apparatus including: a forming zone for forming a glass ribbon; a conveying device for conveying the glass ribbon along a longitudinal direction; and a cutting device for cutting the glass ribbon along a width direction to cut out a glass sheet, A detection device is provided that measures the temperature of a cut-side end of the glass ribbon after cutting by the cutting device, a glass sheet, or one of the two, and detects defects occurring in the measurement object based on the measurement result, The glass sheet manufacturing apparatus, wherein the detection device measures the temperature of the measurement object by measuring a temperature distribution using thermography.

Images