Glass plate manufacturing method

Abstract

To accurately discriminate between types of defects of a glass plate during transportation thereof in a vertical posture.SOLUTION: A method for producing a glass plate G comprises: a molding step S1 of molding a glass ribbon Gr using a down-draw method; a cutting step S3 of cutting a glass plate G by cutting the molded glass ribbon Gr into a prescribed length; a transportation step S4 of transporting the cut glass plate G in a vertical posture in parallel to a principal surface of the glass plate G; and an inspection step of inspecting the glass plate G during the transportation step S4. The inspection step comprises: a first inspection step S6 of specifying coordinates of a defect of the glass plate G; and a second inspection step S7 of discriminating a type of the defect positioned in the coordinates specified in the first inspection step S6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a glass sheet, which includes a step of inspecting the formed glass sheet for the presence or absence of defects while it is being transported. [Background technology]

[0002] As is well known, various glass plates, including glass plates for flat panel displays (FPDs) such as liquid crystal displays and electroluminescence displays, are manufactured by forming molten glass melted in a melting furnace into a band-shaped glass ribbon, sufficiently cooling the glass ribbon, and then cutting it to a predetermined size. Here, in addition to the float method, downdraw methods such as the overflow downdraw method (fusion method) and the slot downdraw method are generally used to form the glass ribbon.

[0003] In the down-draw method, a glass ribbon is formed in a vertical position. From the viewpoint of saving space in the manufacturing facility, in order to eliminate the process of changing the orientation of the glass sheet, the cutting process, edge cutting process, transporting process, inspection process, and packaging process are performed in the vertical position.

[0004] However, when a glass plate is transported in a vertical position, the upper end is supported by hanging and transported, so the glass plate is prone to shaking. If an inspection is performed in this state, the portion displaced in the plate thickness direction due to shaking is likely to go out of focus, making accurate inspection difficult. An inspection process that solves this problem is disclosed in, for example, Patent Document 1. In the inspection process disclosed in this document, the upper and lower portions of a vertically oriented glass plate are clamped, and a tensile force is applied in the vertical direction to suppress the amplitude of shaking and prevent the portion to be inspected from going out of focus.

[0005] Incidentally, typical defects in glass sheets include bubble defects and foreign matter defects (e.g., peeling from refractories, etc.), and bubble defects and foreign matter defects have different effects on the quality of the glass sheet. Therefore, the allowable size of bubble defects and the allowable size of foreign matter defects are different, and even for defects of the same size, the pass / fail criteria differ depending on the type of defect. In addition, by feeding back information on the type of defect to upstream processes such as the melting process and the molding process, it is possible to reduce defects and improve the yield. Therefore, it is necessary to distinguish between bubble defects and foreign matter defects. An example of an inspection method for this purpose is disclosed in Patent Document 2. In the inspection process disclosed in this document, a bright field optical system and a dark field optical system are combined to identify the coordinates of the defect, and an image of the defect is captured, and the type of the defect is identified based on the captured image of the defect. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-236771 A [Patent Document 2] JP 2018-112411 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional inspection method described in Patent Document 2, the coordinates and type of a defect are specified simultaneously, making it difficult to image the defect in the glass plate with high accuracy and accurately identify the type of the defect.

[0008] The present invention has as its technical objective the accurate identification of the type of defect in a glass sheet in a vertical position. [Means for solving the problem]

[0009] The present invention, which has been invented to solve the above problems, is a method for manufacturing a glass sheet, comprising: a forming step of forming a glass ribbon by a down-draw method; a cutting step of cutting the formed glass ribbon into a predetermined length to cut out a glass sheet; a transport step of transporting the cut out glass sheet in a vertical position parallel to a main surface of the glass sheet; and an inspection step of inspecting the glass sheet during the transport step, wherein the inspection step includes a first inspection step of specifying coordinates of a defect in the glass sheet, and a second inspection step of identifying the type of the defect located at the coordinates specified in the first inspection step. According to this configuration, by separating the identification of the defect coordinates and the identification of the defect type into separate steps, the type of defect can be accurately identified for a glass sheet transported in a vertical position.

[0010] In the above-mentioned configuration, it is preferable that the upper and lower portions of the glass plate are clamped in the inspection step. With such a configuration, it is possible to suppress the amplitude of vibration of the glass plate to be small, and the glass plate can be accurately inspected.

[0011] In the above-mentioned configuration, it is preferable that the clamping mechanism that clamps the glass plate applies a tensile force to the glass plate in the vertical direction and the width direction. With such a configuration, the amplitude of the vibration of the glass plate can be reduced, and the glass plate can be inspected more accurately.

[0012] In the above-described configuration, the first inspection step preferably includes a linear light source and a line sensor camera arranged along a vertical direction. According to this configuration, the linear light source and the line sensor camera can be made to pass once over the glass sheet to capture an image of the entire main surface of the glass sheet, so that the coordinates of defects on the entire main surface of the glass sheet can be quickly identified.

[0013] In the above configuration, the second inspection step preferably has an imaging system, the imaging system having a light source unit that irradiates the glass plate with inspection light, a microscopic optical unit that enlarges an image of the defect located at the coordinates specified in the first inspection step, and an imaging unit that captures the enlarged image of the defect. With this configuration, the image of the defect can be captured at an appropriate magnification, and the defect can be directly enlarged and visually inspected, so that the type of defect can be more accurately identified.

[0014] In the above-described configuration, it is preferable that the imaging system is driven in the vertical direction and the width direction of the glass plate. With such a configuration, the imaging system can be easily moved to the coordinates of the defect identified in the first inspection step.

[0015] In the above configuration, the conveying step preferably includes carrying the glass plate into the second inspection step and carrying the glass plate out of the second inspection step, and the imaging system is made to wait below the lower end of the glass plate while the glass plate is being carried into the second inspection step and while the glass plate is being carried out of the second inspection step. In general, when the magnification of the imaging system is increased, the focal length of the imaging system is shortened. Therefore, it is necessary to make the distance between the imaging system and the glass plate closer than in the conventional inspection method, and there is a risk of the glass plate colliding with the imaging system during the conveyance of the glass plate. By making the imaging system wait below the lower end of the glass plate, it is possible to prevent the imaging system from colliding with the glass plate while the glass plate is being carried into the second inspection step and while the glass plate is being carried out of the second inspection step.

[0016] In the above-mentioned configuration, it is preferable that the imaging system is kept on standby at a substantially central portion in the width direction below the lower end of the glass plate while the glass plate is being carried into the second inspection process and while the glass plate is being carried out from the second inspection process. With this configuration, it is possible to prevent a collision between the imaging system and the glass plate and to shorten the moving distance of the imaging system from the standby position to the coordinates of the defect identified in the first inspection process, thereby shortening the time required for the second inspection process.

[0017] In the above configuration, it is preferable that in the first inspection step, the coordinates of the defect based on the end face of the glass plate are recorded, and in the second inspection step, the end face of the glass plate is detected using a position detection means, and the imaging system is moved to a coordinate position based on the end face. Due to mechanical errors in the transport step, the glass plate transported to the second inspection step does not necessarily stop at the same position. If the coordinate reference for the second inspection step is constant regardless of the stopping position of the glass plate, if the stopping position of the glass plate varies greatly, the defect to be imaged may fall out of the field of view of the imaging system and may not be imaged, and the type of defect may not be identified. By detecting the position of the end face of the glass plate in the second inspection step and using it as the coordinate reference, the imaging system can be moved to a position where the defect can be included in the field of view.

[0018] In the above configuration, the inspection step preferably further includes a third inspection step in which an inspector visually inspects the appearance of the glass plate, and the third inspection step is performed in parallel with the second inspection step. By performing the second inspection step and the third inspection step in parallel, the inspection time and the inspection space can be reduced compared to performing the second inspection step and the third inspection step separately.

[0019] In the above configuration, in the inspection process, it is preferable that the upper region in the vertical direction of the glass sheet is inspected in the third inspection process, and the lower region is inspected in the second inspection process, and the region inspected in the second inspection process is wider than the region inspected in the third inspection process. Defects in the glass sheet occur continuously along the flow direction in the forming process, that is, the vertical direction. By dividing the regions inspected in the second inspection process and the third inspection process into upper and lower parts, the entire range in the width direction can be inspected in each inspection process, and the distribution of defects in the width direction can be obtained. In addition, the glass sheet is supported and suspended from above in a vertical position and transported, but by placing the region inspected in the second inspection process below the glass sheet, it is possible to prevent interference between equipment for carrying out the second inspection process and equipment for transporting the glass sheet. In addition, the third inspection process inspects the appearance of the glass sheet, such as striae and uneven thickness, and does not need to inspect a wide region. By making the region inspected in the second inspection process wider than the region inspected in the third inspection process, it is possible to identify as many types of defects whose coordinates were identified in the first inspection process as possible.

[0020] In the above configuration, it is preferable that the second inspection step is performed by excluding the area to be inspected in the third inspection step. Defects in the glass plate occur continuously along the vertical direction. Therefore, it is not necessary to inspect the entire range in the vertical direction, but it is sufficient to inspect the entire range in the width direction. With this configuration, it is possible to reduce the time required for the second inspection step and the third inspection step.

[0021] In the above configuration, it is preferable that the number of defects identified in the second inspection process is smaller than the number of coordinates of the defects identified in the first inspection process. The first inspection process can be inspected in the time it takes for a line sensor camera to pass the glass plate once. On the other hand, in the second inspection process, an imaging system is driven to capture images of the coordinates of the defects identified in the first inspection process, so that if the number of defects whose coordinates are identified in the first inspection process is greater than a certain number, the inspection time of the second inspection process is longer than that of the first inspection process. Therefore, the number of defects captured in the second inspection process is limited to a certain number or less. With this configuration, it is possible to prevent the time required for the inspection process from becoming longer than necessary. Effect of the Invention

[0022] According to the present invention as described above, the type of defect in a glass sheet in a vertical position can be accurately identified. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a schematic diagram of a method for producing a glass plate. [Diagram 2] FIG. 2 is a schematic diagram of a molding step and a slow cooling step. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. 13 is a schematic diagram of an edge cutting process. [Figure 6] FIG. 13 is a schematic diagram of a first inspection step. [Figure 7] 1 is a schematic diagram of a bright-field inspection machine and a dark-field inspection machine. [Figure 8] FIG. 11 is a schematic diagram of a second inspection step. [Figure 9] FIG. 2 is a schematic diagram of an imaging system. [Figure 10] FIG. 11 is a schematic diagram of a third inspection step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of the method for producing a glass plate according to the present invention will be described.

[0025] 1 shows an embodiment of the method for manufacturing a glass sheet according to the present invention. The glass sheet manufacturing apparatus 1 includes a forming process S1 for stretching the molten glass Gm in the downward direction X to form a band-shaped glass ribbon Gr, an annealing process S2 for annealing the glass ribbon Gr formed in the forming process S1, a cutting process S3 for cutting the glass ribbon Gr annealed in the annealing process S2 to a predetermined size to obtain a glass sheet G, a transporting process S4 for transporting the cut glass sheet G in a vertical position in the width direction Y, an edge cutting process S5 for removing thick parts (edges) formed at both ends in the width direction Y, a first inspection process S6, a second inspection process S7, and a third inspection process S8 for inspecting the glass sheet G obtained in the edge cutting process S5, and a packaging process S9 for packaging the glass sheet G that has passed the inspection.

[0026] In the forming step S1, a glass ribbon Gr is formed from molten glass Gm melted in a melting furnace (not shown) by using an overflow downdraw method. In detail, as shown in FIG. 2, a forming body 21 is arranged in the forming section 2, and the molten glass Gm overflowing from both sides of a top 211 of the forming body 21 having a wedge-shaped cross section is caused to flow down along an outer surface portion 212 of the forming body 21 and is fused and integrated at a lower end portion 213 of the forming body, thereby forming the glass ribbon Gr. In this case, the molten glass Gm (or the glass ribbon Gr) is guided by edge rollers 22 and drawn in the downward direction X. Note that the forming step S1 is not limited to the overflow downdraw method, and other downdraw methods such as a slot downdraw method or a redraw method, or a float method may be used.

[0027] In the annealing step S2, the glass ribbon Gr is annealed. The annealing furnace has an internal space provided with a predetermined temperature gradient toward the downward direction X. As shown in Fig. 2, the glass ribbon Gr continuous with the forming body 21 is annealed so that the temperature decreases as the glass ribbon Gr moves in the internal space of the annealing furnace in the downward direction X while being guided by the annealer rollers 31 arranged in the annealing section 3. Accordingly, internal strain of the glass ribbon Gr is removed.

[0028] In the cutting step S3, the glass ribbon Gr is cut to a predetermined length. As shown in FIG. 3, the cutting unit 4 includes an arm 41, and first, both ends of the glass ribbon Gr in the width direction Y are clamped by a chuck 42 attached to the arm 41. Next, in a state in which the support bar 44 supports the glass ribbon Gr from the back side, the wheel cutter 43 is made to travel along the width direction Y of the glass ribbon Gr along the planned cutting line on one main surface of the glass ribbon Gr to form a scribe line 46. Thereafter, the arm 41 rotates with the fulcrum bar 45 as a fulcrum to apply bending stress along the scribe line 46, thereby cutting (cleaving) the glass ribbon Gr along the scribe line 46. As a result, a glass sheet G of a predetermined length is obtained from the glass ribbon Gr. In this embodiment, in the cutting step S3, the glass ribbon Gr is cut while remaining in a vertical position (for example, a vertical position), and the obtained glass sheet G is transported in the transport step S4 while remaining in a vertical position. Note that the method of cutting the glass ribbon Gr is not limited to cleaving by bending stress, and may be, for example, laser cleaving or laser melting.

[0029] In the conveying step S4, the glass sheet G produced in the cutting step S3 is conveyed in a vertical position to each step from the edge cutting step S5 onwards. As shown in Fig. 4, the conveying section 5 includes an upper clamping mechanism 51, an upper guide rail 52, and a moving body 53. The upper clamping mechanism 51 clamps the upper part of the glass sheet G in the vertical position, and then the moving body 53 moves along the upper guide rail 52 extending in the width direction Y of the glass sheet G to convey the glass sheet G.

[0030] In the edge cutting process S5, both ends (edges) of the glass sheet G in the width direction Y are cut. The both ends of the glass sheet G in the width direction Y may be relatively thicker than the center of the width direction Y, and these both ends are called edge parts. As shown in FIG. 5, the edge cutting unit 6 includes a clamping unit 61, a wheel cutter 62, and a support bar 63 in the first station ST1. The glass sheet G transported to the first station ST1 by the transport process S4 is delivered to the clamping unit 61, and is supported by hanging the upper part in a vertical position. The wheel cutter 62 forms a scribe line 67 along the upward direction X of the glass sheet G while the support bar 63 supports the back surface of the glass sheet G. Thereafter, the glass sheet G is delivered to the upper clamping mechanism 51 in the transport process S4 and transported to the second station ST2. The second station ST2 includes a clamping unit 64, a pressing unit 65, and a support bar 66. The glass sheet G transported to the second station ST2 by the transport step S4 is handed over to the clamping unit 64 and supported by hanging its upper part in a vertical position. The pressing unit 65 presses the ears 68 toward the back surface side, thereby bending the glass sheet G with the support bar 66 as a fulcrum. This applies bending stress to the scribe line 67 and its vicinity, and the glass sheet G is cleaved in the upward direction X along the scribe line 67. The glass sheet G from which the ears 68 have been removed is transported to an inspection step by the transport step S4.

[0031] The inspection process includes a first inspection process S6 for identifying coordinates of defects in the glass sheet G, a second inspection process S7 for identifying the type of the defect in the glass sheet G, and a third inspection process S8 for inspecting defects that appear regularly in the flow direction and defects that cannot be detected in the first inspection process S6 and the second inspection process S7. The first inspection process S6, the second inspection process S7, and the third inspection process S8 will be described in detail below.

[0032] In the first inspection process S6, a first inspection device 7 including a support mechanism 71, a bright-field inspection machine 72, and a dark-field inspection machine 73 is used as shown in Fig. 6. The glass plate G transported to the first inspection process S6 by the transport process S4 is handed over to the support mechanism 71. In detail, an upper clamping mechanism 711 clamps the upper part of the glass plate G, and a lower clamping mechanism 712 clamps the lower part of the glass plate G. This makes it possible to keep the amplitude of vibration of the glass plate G during inspection small, and to accurately identify the coordinates of defects.

[0033] The chucks constituting the upper clamping mechanism 711 and the lower clamping mechanism 712 are each connected to an air cylinder 713. The air cylinder 713 can feed compressed air from an air supply device (e.g., an air compressor) not shown, and can suck and discharge the air remaining in the air cylinder 713 by an air suction device (e.g., a vacuum pump) not shown. The air pressure in the air cylinder 713 is adjusted by the air supply device and the air suction device, and a piston contained in the cylinder is moved by the pressure to apply a predetermined force. The upper downstream chuck group 7111 moves upward and downstream, the upper upstream chuck group 7112 moves upward and upstream, the lower downstream chuck group 7121 moves downward and downstream, and the lower upstream chuck group 7122 moves downward and upstream, thereby applying a tensile force to the glass sheet. That is, the glass sheet G is applied with a tensile force in the vertical direction X and the width direction Y. This makes it possible to reduce the amplitude of the vibration of the glass sheet G, and to more accurately identify the coordinates of the defect.

[0034] After the tensile force is applied to the glass plate G, as shown in FIG. 7, the main surface of the glass plate G is imaged using a first inspection device 7 equipped with a bright-field inspection machine 72 and a dark-field inspection machine 73. The bright-field inspection machine 72 is equipped with a bright-field light source 721 and a bright-field camera 722. The bright-field camera 722 is arranged on the optical axis of the bright-field light source 721 so as to capture the light irradiated from the bright-field light source 721 to the glass plate G and transmitted through the glass plate G. A light shielding plate 723 that forms a bright part and a dark part in the field of the bright-field camera 722 is installed between the glass plate G and the bright-field camera 722. The dark-field inspection machine 73 is equipped with a dark-field light source 731 and a dark-field camera 732, and the dark-field camera 732 is arranged at a position off the optical axis of the dark-field light source 731 so as to capture the light irradiated from the dark-field light source 731 to the glass plate G and scattered by defects in the glass plate G. Moreover, the bright-field light source 721 and the dark-field light source 731 are arranged in a plurality of positions along the vertical direction X of the glass plate G, forming a linear light source. Similarly, the bright-field camera 722 and the dark-field camera 732 are arranged in a plurality of positions along the vertical direction X, forming a line sensor camera, respectively. This allows the glass plate G to be passed once through the linear light source and the line sensor camera, thereby allowing the image of the entire main surface of the glass plate G to be quickly identified. As shown in FIG. 7, the bright-field light source 721 and the dark-field light source 731 may be unitized, and the image capturing position of the bright-field inspection machine 72 on the glass plate G may be made to coincide with the image capturing position of the dark-field inspection machine 73. In this case, a beam splitter 74 is installed between the glass plate G and the light shielding plate 723, using a dark-field light source 731 having a wavelength different from that of the bright-field light source 721, and the light captured by the bright-field camera 722 and the light captured by the dark-field camera 732 are separated. Moreover, the bright-field light source 721 and the dark-field light source 731 may not be unitized, and the optical paths of the bright-field inspection machine 72 and the dark-field inspection machine 73 may be independent. Note that, although LED light sources are used as the bright-field light source 721 and the dark-field light source 731 in this embodiment, metal halide lamps or laser light sources may also be used.

[0035] The bright-field inspection machine 72 and the dark-field inspection machine 73 can move together in the width direction Y of the glass sheet G. While moving in the width direction Y of the glass sheet G, an image of the entire main surface of the glass sheet G is captured. The obtained bright-field image and dark-field image are compared to identify the presence or absence of defects, and the coordinates are recorded in a database (not shown). The coordinates are based on the upper end and downstream end surface of the glass sheet G.

[0036] After the first inspection step S6 is completed, the glass sheet G is delivered to the upper clamping mechanism 51 in the transport step S4, and then transported to the second inspection step S7.

[0037] 8, a second inspection device 8 including a support mechanism 81, an imaging system 82, and an imaging system drive mechanism 83 is used in the second inspection process S7. The glass plate G transported to the second inspection process S7 by the transport process S4 is delivered to the support mechanism 81. In detail, an upper clamping mechanism 811 clamps the upper part of the glass plate G, and a lower clamping mechanism 812 clamps the lower part of the glass plate G.

[0038] The chucks constituting the upper clamping mechanism 811 and the lower clamping mechanism 812 are each connected to an air cylinder 813. The air cylinder 813 is connected to an air supply device and an air suction device (not shown) like the air cylinder 713, and applies a predetermined force. The upper downstream chuck group 8111 applies a tensile force upward and downstream, the upper upstream chuck group 8112 applies a tensile force upward and upstream, the lower downstream chuck group 8121 applies a tensile force downward and downstream, and the lower upstream chuck group 8122 applies a tensile force downward and upstream in the vertical direction X and the width direction Y of the glass sheet G. The tensile force is preferably 120 N or more.

[0039] With the upper clamping mechanism 811 and the lower clamping mechanism 812 clamping the glass sheet G, the positions of the upper end and downstream end face of the glass sheet G are detected and recorded using the position detection means 84. For example, a transmission type laser sensor can be used as the position detection means 84. This makes it possible to move the imaging system to a position where the defect can be accommodated within the field of view of the imaging unit 823.

[0040] 9, the imaging system 82 includes a light source unit 821, a microscopic optical unit 822, and an imaging unit 823. The light source unit 821 irradiates the glass plate G with inspection light, and an image of a defect in the glass plate G is enlarged by the microscopic optical unit 822 and captured by the imaging unit 823. The image of the defect includes an image of the inspection light reflected by the defect and an image of the light reflected by the rear surface of the glass plate G and blocked by the defect. In this embodiment, an LED light source is used as the light source unit 821, but a metal halide lamp or a laser light source may also be used.

[0041] The imaging system 82 is attached to a vertical direction drive mechanism 832, which is attached to a width direction drive mechanism 831. The vertical direction drive mechanism 832 and the width direction drive mechanism 831 are equipped with a servo motor, a linear guide, and a ball screw, and are driven in the vertical direction X and the width direction Y, respectively. This allows the imaging system 82 to move to any position within the area where inspection is performed in the second inspection step S7 of the glass sheet G and capture an image. Note that the driving method of the vertical direction drive mechanism 832 and the width direction drive mechanism 831 is not limited to the ball screw, and a timing belt, a chain, or the like may also be used. Also, a linear motor may be used instead of the servo motor and the ball screw.

[0042] When the glass plate G is carried into the second inspection process S7 in the transport process S4, it is preferable that the imaging system 82 waits in the region A below the lower end of the glass plate G shown in FIG. 8. This makes it possible to prevent the glass plate G from coming into contact with the imaging system 82 even if it is greatly shaken during the carrying-in to the second inspection process S7. Furthermore, by having the imaging system 82 wait in the region B at the approximate center in the width direction Y of the glass plate G, it is possible to shorten the moving distance to the coordinates of the defect identified in the first inspection process S6 even if the coordinates of the defect are located on the upstream side or downstream side of the farthest upper side. It is preferable that the imaging system 82 waits in the region A or region B when carrying the glass plate G out of the second inspection process S7, as in the carrying-in.

[0043] After the glass sheet G is clamped by the upper clamping mechanism 811 and the lower clamping mechanism 812, the imaging system 82 is moved to the coordinates of the defect identified in the first inspection step S6. The coordinates are based on the upper end and downstream end surface of the glass sheet G detected by the position detection means 84. When the imaging system 82 moves from the region A or region B to the coordinates of the defect, the imaging system 82 passes between the lower downstream chuck group 8121 and the lower upstream chuck group 8122. The number of coordinates to be imaged is limited to a predetermined number or less so that the time required for the second inspection step S7 is within the transport takt time. After imaging the defect at the coordinates to be imaged, the imaging system 82 passes between the lower downstream chuck group 8121 and the lower upstream chuck group 8122 again, moves to the region A or region B, and waits.

[0044] The type of the defect is identified based on the image of the defect captured in the second inspection process S7. The identified type of defect is linked to the number and coordinate information of the defects identified in the first inspection process S6, and is stored in a database (not shown).

[0045] As shown in FIG. 10, in the third inspection step S8, a third inspection device 9 including a third inspection table 91, a third inspection light source 92, and a light source cover 93 is used. In the third inspection step S8, an inspector stands on the third inspection table 91 at a predetermined height and visually detects defects such as striae and uneven thickness of the glass sheet G that cannot be found in the first inspection step S6 and the second inspection step S7, and defects that appear regularly in the flow direction. By irradiating the end face of the glass sheet G with inspection light from the third inspection light source 92, the visibility of defects such as striae and uneven thickness is improved and they are easily detected. Furthermore, by covering the third inspection light source 92 and the end face of the glass sheet G with an openable light source cover 93, light that has not entered the end face of the glass sheet G is blocked, improving the workability of the inspector. Since the light source cover 93 is opened and closed by a toggle mechanism, the glass sheet G can be tightly sandwiched, and light can be blocked more effectively. In this embodiment, an LED light source is used as the third inspection light source 92, but a metal halide lamp or a laser light source may also be used.

[0046] The third inspection device 9 is disposed at the same position as the second inspection device 8 so that the second inspection process S7 and the third inspection process S8 can be performed in parallel. This allows the time required for the inspection process to be shortened and the space to be saved. In addition, the lower region C in the vertical direction X of the glass sheet G is inspected in the second inspection process S7, and the upper region D narrower than the region C is inspected in the third inspection process S8. Defects in the glass sheet G occur continuously along the flow direction in the forming process, that is, along the vertical direction X. By dividing the inspection region of the glass sheet G into the lower region C and the upper region D, the entire range across the width direction Y can be inspected in each inspection process, and the distribution of defects across the width direction Y can be obtained. In addition, the glass sheet G is supported and transported in a vertical position while being suspended from above, but by placing the region to be inspected in the second inspection process S7 below the glass sheet G, interference between the equipment for performing the second inspection process S7 and the transport unit 5 can be prevented. Furthermore, the third inspection process S8 is for inspecting the appearance of the glass sheet G, such as striae and uneven thickness, and does not need to inspect a wide area. By making area C wider than area D, it is possible to identify as many types of defects as possible, the coordinates of which were identified in the first inspection process S6. This makes it possible to shorten the time required for the second inspection process S7 and the third inspection process S8.

[0047] In addition, it is preferable to make the number of defects identified in the second inspection process S7 smaller than the number of coordinates of defects identified in the first inspection process S6. In the first inspection process S6, inspection can be performed in the time required for passing the line sensor camera once over the glass plate G. On the other hand, in the second inspection process S7, the imaging system 82 is driven to capture images of the coordinates of the defects identified in the first inspection process S6, so that if the number of defects whose coordinates are identified in the first inspection process S6 is greater than a certain number, the inspection time of the second inspection process S7 will be longer than that of the first inspection process S6. Therefore, the number of defects captured in the second inspection process S7 is limited to a certain number or less. With this configuration, it is possible to prevent the time required for the second inspection process S7 from becoming longer than necessary.

[0048] The inspection result of the glass sheet G is determined based on the results of the first inspection step S6, the second inspection step S7, and the third inspection step S8.

[0049] After the second inspection process S7 and the third inspection process S8 are completed, the glass sheet G is delivered to the upper clamping mechanism 51 in the transport process S4. If the glass sheet G passes the inspection, it is transported to a packaging process S9, and if it fails the inspection, it is discarded in a waste place (not shown).

[0050] According to the glass sheet manufacturing apparatus 1 of this embodiment configured as described above, by separating the identification of defect coordinates and the identification of defect type into separate processes, it is possible to accurately identify the type of defect for a glass sheet G transported in a vertical position.

[0051] The present invention is not limited to the configuration of the above embodiment, and the above-mentioned effects and advantages are not limited to the above-mentioned embodiment. The present invention is not limited to the above. Various modifications can be made without departing from the spirit of the present invention. It is.

[0052] In the above embodiment, in the first inspection step S6 and the second inspection step S7, the upper and lower parts of the glass sheet G are clamped and tensile forces are applied in the vertical direction X and the width direction Y, but this is not limited thereto. It is not necessary to apply tensile forces to the glass sheet G, and only the upper part of the glass sheet G may be clamped without clamping the lower part.

[0053] In the above embodiment, in the first inspection step S6, the bright-field inspection machine 72 and the dark-field inspection machine 73 identify the coordinates of the defect using the light transmitted through the glass plate G, but the present invention is not limited to this. A method of identifying the coordinates of the defect using the light reflected by the glass plate G may also be used.

[0054] In the above embodiment, in the first inspection step S6, the inspection is performed by passing the line sensor camera over the glass plate G, but the present invention is not limited to this. The line sensor camera may be fixed and the glass plate G may be moved relatively to the line sensor camera to capture an image of the entire glass plate.

[0055] In the above embodiment, in the second inspection process S7, the imaging system 82 images the defect using the light reflected by the glass plate G, but the present invention is not limited to this. It is also possible to use a method of imaging the defect using the light transmitted through the glass plate G.

[0056] In the above embodiment, in the second inspection step S7, when the glass plate G is carried in or out, the imaging system 82 is made to wait in the area A or the area B, but this is not limited thereto. When the glass plate G is carried in or out, the imaging system 82 may move in a direction perpendicular to the surface of the glass plate and wait there.

[0057] In the above embodiment, the third inspection device 9 is disposed above the second inspection device 8, and the second inspection step and the third inspection step are performed in parallel, but this is not limited to the above. The third inspection device 9 may be disposed downstream of the second inspection device 8, and the third inspection step S8 may be performed after the second inspection step S7 is completed. Furthermore, the entire surface of the glass sheet G may be inspected in the second inspection step S7 and the third inspection step S8, and the third inspection step may be omitted. [Industrial Applicability]

[0058] INDUSTRIAL APPLICABILITY The present invention can be suitably used in the manufacture of glass sheets, which includes a step of inspecting the formed glass sheet for the presence or absence of defects during transportation. [Explanation of symbols]

[0059] S1 Molding process S2 slow cooling process S3 Cutting process S4 Transport process S5 Ear cutting process S6 First inspection process S7 Second inspection process S8 Third inspection process S9 Packing process 1. Glass plate manufacturing equipment 7 First Inspection Device 71 Support mechanism 72 Brightfield Inspection Machine 73 Dark Field Inspection Machine 8. Second Inspection Equipment 81 Support mechanism 82 Imaging system 821 Light source section 822 Micro-Optics Department 823 Imaging unit 84 Position detection means 9. Third Inspection Equipment G Glass plate Gr Glass ribbon

Claims

1. A method for manufacturing a glass sheet, comprising: a forming step of forming a glass ribbon by a down-draw method; a cutting step of cutting the formed glass ribbon into a glass sheet at predetermined lengths; a conveying step of conveying the cut glass sheet in a vertical position parallel to a main surface of the glass sheet; and an inspection step of inspecting the glass sheet during the conveying step, The inspection process includes a first inspection process for identifying coordinates of a defect in the glass plate, and a second inspection process for identifying a type of the defect located at the coordinates identified in the first inspection process, The second inspection step has an imaging system, the imaging system includes a light source unit that irradiates the glass plate with inspection light, a microscopic optical unit that enlarges an image of the defect located at the coordinates specified in the first inspection step, and an imaging unit that captures the enlarged image of the defect, In the inspection step, the upper and lower portions of the glass plate are clamped, In the second inspection step, an upper clamping mechanism clamps an upper portion of the glass plate and a lower clamping mechanism clamps a lower portion of the glass plate; the lower clamping mechanism includes a lower upstream chuck group located on the upstream side in a conveying direction of the glass sheet, and a lower downstream chuck group located on the downstream side, a distance between the lower upstream chuck group and the lower downstream chuck group is greater than a distance between the plurality of chucks included in the lower upstream chuck group and a distance between the plurality of chucks included in the lower downstream chuck group; a second inspection step of moving the imaging system from a position below a lower end of the glass plate and approximately at the center in the width direction of the glass plate to a position of the defect, the imaging system passing between the lower upstream group of chucks and the lower downstream group of chucks.

2. 2. The method for manufacturing a glass sheet according to claim 1, wherein the clamping mechanism for clamping the glass sheet applies tensile forces to the glass sheet in vertical and width directions.

3. 3. The method for manufacturing a glass plate according to claim 1, wherein the first inspection step includes a linear light source and a line sensor camera aligned in a vertical direction.

4. 4. The method for manufacturing a glass plate according to claim 1, wherein the imaging system is driven in the vertical direction and the width direction of the glass plate.

5. The conveying step includes carrying the glass plate into the second inspection step and carrying the glass plate out of the second inspection step, 5. The method for manufacturing a glass plate according to claim 3, wherein the imaging system is kept waiting below a lower end of the glass plate while the glass plate is being transported to the second inspection process and while the glass plate is being transported from the second inspection process.

6. 6. The method for manufacturing a glass plate according to claim 5, wherein the imaging system is kept on standby at approximately the center in the width direction below the lower end of the glass plate while the glass plate is being transported to the second inspection process and while the glass plate is being transported from the second inspection process.

7. In the first inspection step, the coordinates of the defect relative to an edge surface of the glass plate are recorded; The method for manufacturing a glass plate according to any one of claims 3 to 6, characterized in that in the second inspection step, an edge surface of the glass plate is detected using a position detection means, and the imaging system is moved to a position of the coordinates based on the edge surface.

8. The inspection step further includes a third inspection step in which an inspector visually inspects the appearance of the glass plate, The method for manufacturing a glass sheet according to any one of claims 1 to 7, wherein the third inspection step is carried out in parallel with the second inspection step.

9. In the inspection step, an upper region in a vertical direction of the glass plate is inspected in the third inspection step, and a lower region is inspected in the second inspection step, The method for manufacturing a glass plate according to claim 8, wherein an area inspected in the second inspection step is larger than an area inspected in the third inspection step.

10. The method for manufacturing a glass plate according to claim 9 , wherein the second inspection step is performed by excluding a region that is inspected in the third inspection step.

11. The method for manufacturing a glass plate according to any one of claims 1 to 10, characterized in that the number of defects identified in the second inspection step is smaller than the number of coordinates of the defects identified in the first inspection step.

Images