JP7616508B2 - Glass plate manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing glass sheets that includes a process for inspecting the formed glass sheets for defects while they are being transported.

As is well known, various glass sheets, including glass sheets for flat panel displays (FPDs) such as liquid crystal displays and electroluminescent 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 specified size. In addition to the float method, downdraw methods such as the overflow downdraw method (fusion method) and the slot downdraw method are commonly used to form the glass ribbon.

In the down-draw method, glass ribbon is formed in a vertical position. From the perspective of saving space in the manufacturing facility, the cutting process, edge cutting process, transport process, inspection process, and packaging process are carried out in a vertical position with the aim of eliminating the process of changing the orientation of the glass sheet.

However, when a glass plate is transported in a vertical position, the upper end is suspended and supported, which means that the plate is prone to shaking. If an inspection is performed in this state, the area displaced in the plate thickness direction by the 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 parts of a vertically oriented glass plate are clamped, and a tensile force is applied in the vertical direction to reduce the amplitude of the shaking and prevent the area to be inspected from going out of focus.

Representative defects in glass sheets include bubble defects and foreign matter defects (e.g., flaking 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 yields. Therefore, it is necessary to distinguish between bubble defects and foreign matter defects. An example of an inspection method for this purpose is that 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 defect is identified based on the captured image of the defect.

JP 2009-236771 A JP 2018-112411 A

However, the conventional inspection method described in Patent Document 2 identifies the coordinates and type of defect simultaneously, making it difficult to capture images of defects in glass plates with high accuracy and accurately identify their types.

The technical objective of the present invention is to accurately identify the type of defect on a vertically oriented glass sheet.

The present invention, which was invented to solve the above problems, is a method for manufacturing a glass sheet, comprising: a forming process for forming a glass ribbon by a down-draw method; a cutting process for cutting the formed glass ribbon into glass sheets at predetermined lengths; a transport process for transporting the cut glass sheet in a vertical position parallel to the main surface of the glass sheet; and an inspection process for inspecting the glass sheet during the transport process, wherein the inspection process includes a first inspection process for identifying coordinates of defects in the glass sheet, and a second inspection process for identifying the type of the defect located at the coordinates identified in the first inspection process. With this configuration, by separating the identification of defect coordinates and the identification of defect type into separate processes, the type of defect can be accurately identified for glass sheets transported in a vertical position.

In the above configuration, it is preferable that the upper and lower parts of the glass plate are clamped in the inspection process. With this configuration, the amplitude of the glass plate's vibration can be kept small, allowing the glass plate to be inspected accurately.

In the above configuration, it is preferable that the clamping mechanism that clamps the glass plate applies a tensile force to the glass plate in the vertical and width directions. With this configuration, the amplitude of the glass plate's vibration can be reduced, and the glass plate can be inspected more accurately.

In the above configuration, the first inspection process preferably has a linear light source and a line sensor camera aligned in the vertical direction. With this configuration, the entire main surface of the glass plate can be imaged by passing the linear light source and the line sensor camera once over the glass plate, so that the coordinates of defects on the entire main surface of the glass plate can be quickly identified.

In the above configuration, the second inspection process preferably has an imaging system, the imaging system preferably having a light source unit that irradiates the glass plate with inspection light, a microscopic optical unit that enlarges the image of the defect located at the coordinates identified in the first inspection process, 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, allowing the type of defect to be identified more accurately.

In the above configuration, it is preferable to drive the imaging system in the vertical direction and the width direction of the glass plate. With this configuration, the imaging system can be easily moved to the coordinates of the defect identified in the first inspection process.

In the above configuration, the transport step includes transporting the glass plate to the second inspection step and transporting the glass plate from the second inspection step, and it is preferable that the imaging system is kept waiting below the lower end of the glass plate while the glass plate is being transported to the second inspection step and while the glass plate is being transported from the second inspection step. Generally, 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 conventional inspection methods, and there is a risk of the glass plate colliding with the imaging system during transport of the glass plate. By having 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 transported to the second inspection step and while the glass plate is being transported from the second inspection step.

In the above configuration, it is preferable to have the imaging system wait 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. This configuration prevents collisions between the imaging system and the glass plate, and shortens the travel distance of the imaging system from the waiting position to the coordinates of the defect identified in the first inspection process, thereby shortening the time required for the second inspection process.

In the above configuration, it is preferable that in the first inspection process, the coordinates of the defect are recorded based on the edge of the glass plate, and in the second inspection process, the edge of the glass plate is detected using a position detection means and the imaging system is moved to a coordinate position based on the edge. Due to mechanical errors in the transport process, the glass plate transported to the second inspection process does not necessarily stop at the same position. If the coordinate reference for the second inspection process is constant regardless of the stopping position of the glass plate, if there is a large variation in the stopping position of the glass plate, the defect to be imaged may fall outside 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 edge of the glass plate in the second inspection process 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.

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

In the above configuration, in the inspection process, the upper region in the vertical direction of the glass plate is inspected in the third inspection process, and the lower region is inspected in the second inspection process, and it is preferable that the region inspected in the second inspection process is wider than the region inspected in the third inspection process. Defects in the glass plate 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 plate 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 plate, interference between the equipment for carrying out the second inspection process and the equipment for transporting the glass plate can be prevented. In addition, the third inspection process inspects the appearance of the glass plate, such as veins 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.

In the above configuration, it is preferable that the second inspection process is performed excluding the area inspected in the third inspection process. Defects in the glass plate occur continuously in 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, the time required for the second inspection process and the third inspection process can be shortened.

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 performed 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 if the number of defects whose coordinates are identified in the first inspection process is greater than a certain number, the inspection time for the second inspection process will be 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. This configuration makes it possible to prevent the time required for the inspection process from becoming longer than necessary.

According to the present invention, the type of defect on a vertically oriented glass plate can be accurately identified.

FIG. 2 is a schematic diagram of a method for producing a glass plate. FIG. 2 is a schematic diagram of a molding step and a slow cooling step. FIG. FIG. FIG. 13 is a schematic diagram of an edge cutting process. FIG. 13 is a schematic diagram of a first inspection step. 1 is a schematic diagram of a bright-field inspection machine and a dark-field inspection machine. FIG. 11 is a schematic diagram of a second inspection step. FIG. 2 is a schematic diagram of an imaging system. FIG. 11 is a schematic diagram of a third inspection step.

One embodiment of the method for manufacturing a glass plate according to the present invention will be described.

Figure 1 shows one embodiment of the glass sheet manufacturing method according to the present invention. The glass sheet manufacturing apparatus 1 includes a forming process S1 in which the molten glass Gm is stretched in the downward direction X to form a band-shaped glass ribbon Gr, an annealing process S2 in which the glass ribbon Gr formed in the forming process S1 is annealed, a cutting process S3 in which the glass ribbon Gr annealed in the annealing process S2 is cut to a predetermined size to obtain a glass sheet G, a conveying process S4 in which the cut glass sheet G is conveyed in the width direction Y in a vertical position, an edge cutting process S5 in which thick parts (edges) formed at both ends in the width direction Y are removed, a first inspection process S6, a second inspection process S7, and a third inspection process S8 in which the glass sheet G obtained in the edge cutting process S5 is inspected, and a packaging process S9 in which the glass sheet G that has passed the inspection is packaged.

In the forming step S1, the glass ribbon Gr is formed from the molten glass Gm melted in a melting furnace (not shown) using the 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 the top 211 of the forming body 21 having a wedge-shaped cross section on both sides is caused to flow down along the outer surface portion 212 of the forming body 21 and fused and integrated at the lower end 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 the edge rollers 22 and stretched 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 the slot downdraw method and the redraw method, or the float method may be used.

In the annealing step S2, the glass ribbon Gr is annealed. The annealing furnace has a predetermined temperature gradient in the internal space toward the downward direction X. As shown in FIG. 2, the glass ribbon Gr connected to the formed body 21 is guided by the annealer rollers 31 arranged in the annealing section 3 and annealed so that the temperature decreases as it moves in the internal space of the annealing furnace in the downward direction X. As a result, the internal strain of the glass ribbon Gr is removed.

In the cutting process 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 the glass ribbon Gr is first clamped at both ends in the width direction Y by a chuck 42 attached to the arm 41. Next, with the support bar 44 supporting the glass ribbon Gr from the back side, the wheel cutter 43 is run 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. Then, 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 process S3, the glass ribbon Gr is cut in a vertical position (for example, a vertical position), and the obtained glass sheet G is transported in a transport process S4 in a vertical position. The method of cutting the glass ribbon Gr is not limited to cutting by bending stress, but may be, for example, laser cutting or laser melting.

In the transport step S4, the glass sheet G produced in the cutting step S3 is transported in a vertical position to each step from the edge cutting step S5 onwards. As shown in FIG. 4, the transport 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 a 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 transport the glass sheet G.

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 section 6 is provided with a clamping section 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 section 61, and the upper part is suspended and supported in a vertical position. The wheel cutter 62 forms a scribe line 67 along the upper direction X of the glass sheet G with the support bar 63 supporting the back surface of the glass sheet G. The glass sheet G is then delivered to the upper clamping mechanism 51 in the transport process S4 and transported to the second station ST2. The second station ST2 is provided with a clamping section 64, a pressing section 65, and a support bar 66. The glass sheet G transported to the second station ST2 by the transport process 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 against the back surface side, 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 cut 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 the inspection process by the transport process S4.

The inspection process includes a first inspection process S6 for identifying the coordinates of defects in the glass sheet G, a second inspection process S7 for identifying the type of 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.

In the first inspection process S6, a first inspection device 7 is used, which includes a support mechanism 71, a bright-field inspection machine 72, and a dark-field inspection machine 73, 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, the upper clamping mechanism 711 clamps the upper part of the glass plate G, and the lower clamping mechanism 712 clamps the lower part of the glass plate G. This makes it possible to keep the amplitude of the vibration of the glass plate G during inspection small, and to accurately identify the coordinates of defects.

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 be fed with 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 predetermined force is applied by moving a piston contained in the cylinder with the pressure. 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 to apply a tensile force to the glass sheet. In other words, 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.

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 bright and dark areas within the field of view 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 entire main surface of the glass plate G to be imaged by passing the linear light source and the line sensor camera once over the glass plate G, so that the coordinates of defects on the entire main surface of the glass plate G can 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 imaging position of the bright field inspection machine 72 on the glass plate G may be made to coincide with the imaging position of the dark field inspection machine 73. In this case, a dark field light source 731 having a wavelength different from that of the bright field light source 721 is used, and a beam splitter 74 is installed between the glass plate G and the light shielding plate 723 to separate the light imaged by the bright field camera 722 from the light imaged by the dark field camera 732. Also, 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. In this embodiment, LED light sources are used as the bright-field light source 721 and the dark-field light source 731, but metal halide lamps or laser light sources may also be used.

The bright-field inspection machine 72 and the dark-field inspection machine 73 can move together in the width direction Y of the glass plate G. While moving in the width direction Y of the glass plate G, the entire main surface of the glass plate G is imaged. The presence or absence of defects is identified by comparing the obtained bright-field image and dark-field image, and the coordinates are recorded in a database (not shown). The coordinates are based on the top end and downstream end surface of the glass plate G.

After the first inspection process S6 is completed, the glass sheet G is handed over to the upper clamping mechanism 51 in the transport process S4, and then transported to the second inspection process S7.

In the second inspection process S7, a second inspection device 8 is used, which includes a support mechanism 81, an imaging system 82, and an imaging system drive mechanism 83, as shown in FIG. 8. The glass plate G transported to the second inspection process S7 by the transport process S4 is handed over to the support mechanism 81. In detail, the upper clamping mechanism 811 clamps the upper part of the glass plate G, and the lower clamping mechanism 812 clamps the lower part of the glass plate G.

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 in the upward and downstream direction, the upper upstream chuck group 8112 applies a tensile force in the upward and downstream direction, the lower downstream chuck group 8121 applies a tensile force in the downward and downstream direction, and the lower upstream chuck group 8122 applies a tensile force in the vertical direction X and width direction Y of the glass sheet G. It is preferable that the tensile force is 120 N or more.

With the upper clamping mechanism 811 and the lower clamping mechanism 812 clamping the glass sheet G, the position of the upper end and downstream end face of the glass sheet G is detected and recorded using the position detection means 84. For example, a transmissive laser sensor can be used as the position detection means 84. This allows the imaging system to be moved to a position where the defect can be placed within the field of view of the imaging unit 823.

As shown in FIG. 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.

The imaging system 82 is attached to a vertical drive mechanism 832, which is attached to a width direction drive mechanism 831. The vertical 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 process S7 of the glass plate G and capture an image. Note that the driving method of the vertical drive mechanism 832 and the width direction drive mechanism 831 is not limited to a ball screw, and a timing belt, chain, etc. may also be used. A linear motor may also be used instead of the servo motor and ball screw.

When the glass plate G is transported to the second inspection process S7 in the transport process S4, it is preferable for the imaging system 82 to wait in area 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 shakes significantly during transport to the second inspection process S7. Furthermore, by having the imaging system 82 wait in area B at approximately the center of the width direction Y of the glass plate G, it is possible to shorten the travel distance to the coordinates of the defect identified in the first inspection process S6 even if the coordinates are located on the upstream or downstream side of the farthest upper side. Note that when the glass plate G is transported out of the second inspection process S7, it is also preferable for the imaging system 82 to wait in area A or area B, as in the case of transport.

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 process S6. The coordinates are based on the upper end and downstream end face of the glass sheet G detected by the position detection means 84. When the imaging system 82 moves from area A or area 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 process S7 is within the transport takt time. After imaging the defect at the coordinates to be imaged, the imaging system 82 passes again between the lower downstream chuck group 8121 and the lower upstream chuck group 8122, moves to area A or area B, and waits.

The type of 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).

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 that cannot be found in the first inspection step S6 and the second inspection step S7, such as striae and uneven thickness of the glass sheet G, 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 does not enter 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.

The third inspection device 9 is arranged 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 space to be saved. In addition, the lower area C in the vertical direction X of the glass sheet G is inspected in the second inspection process S7, and the upper area D narrower than the area 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 area to be inspected of the glass sheet G into the lower area C and the upper area 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, in the conveying process S4, the glass sheet G is supported and conveyed in a vertical position while suspended from above, but by placing the area to be inspected in the second inspection process S7 below the glass sheet G, interference between the equipment for carrying out the second inspection process S7 and the conveying unit 5 can be prevented. In addition, the third inspection process S8 is for inspecting the appearance of the glass sheet G, such as striae and thickness deviation, 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.

It is also 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. The first inspection process S6 can be inspected in the time it takes for the line sensor camera to pass the glass plate G once. 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 if the number of defects whose coordinates are identified in the first inspection process S6 is greater than a certain number, the inspection time for 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. This configuration makes it possible to prevent the time required for the second inspection process S7 from being longer than necessary.

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

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 the packaging process S9, and if it fails the inspection, it is disposed of in a disposal area (not shown).

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 glass sheets G transported in a vertical position.

The present invention is not limited to the configuration of the above embodiment, nor is it limited to the above-mentioned effects and advantages. Various modifications of the present invention are possible without departing from the spirit and scope of the present invention.

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 to the above. 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.

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 light transmitted through the glass plate G, but this is not limited to the above. A method of identifying the coordinates of the defect using light reflected from the glass plate G may also be used.

In the above embodiment, in the first inspection step S6, the glass plate G is inspected by passing it through a line sensor camera, but this is not limited to this. The line sensor camera may be fixed and the glass plate G may be moved relatively to capture an image of the entire glass plate.

In the above embodiment, in the second inspection process S7, the imaging system 82 images the defect using light reflected by the glass plate G, but this is not limited to this. It is also possible to use a method in which the defect is imaged using light that passes through the glass plate G.

In the above embodiment, in the second inspection process S7, the imaging system 82 is placed on standby in area A or area B when the glass plate G is loaded or unloaded, but this is not limited to this. When the glass plate G is loaded or unloaded, the imaging system 82 may move in a direction perpendicular to the surface of the glass plate and be on standby.

In the above embodiment, the third inspection device 9 is disposed above the second inspection device 8, and the second inspection process and the third inspection process 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 process S8 may be performed after the second inspection process S7 is completed. In addition, the entire surface of the glass sheet G may be inspected in the second inspection process S7 and the third inspection process S8, and the third inspection process may be omitted.

The present invention can be suitably used in the manufacture of glass sheets, which includes a process of inspecting the formed glass sheets for defects while they are being transported.

S1 Molding process S2 Slow cooling process S3 Cutting process S4 Transporting process S5 Edge cutting process S6 First inspection process S7 Second inspection process S8 Third inspection process S9 Packing process 1 Glass plate manufacturing device 7 First inspection device 71 Support mechanism 72 Bright field inspection machine 73 Dark field inspection machine 8 Second inspection device 81 Support mechanism 82 Imaging system 821 Light source unit 822 Microscopic optical unit 823 Imaging unit 84 Position detection means 9 Third inspection device G Glass plate Gr Glass ribbon

Claims (11)

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 inspection light onto the glass plate, 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. 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. 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. 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. 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. 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. 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. The inspection step further includes a third inspection step in which an inspector visually inspects the appearance of the glass plate,
The method for producing 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. 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. 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. 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.