Glass manufacturing method and glass manufacturing apparatus

Abstract

We provide technology for measuring the distance between a glass ribbon and an object. [Solution] The glass manufacturing method comprises the following (A) to (D): (A) A strip-shaped glass ribbon is transported at a distance from the object. (B) The real image of one end of the object facing the glass ribbon and the mirror image of the same end reflected in the glass ribbon are captured by a camera. (C) The distance between the real image and the mirror image captured in the captured image is measured. (D) The distance between the glass ribbon and the object is calculated from the distance between the real image and the mirror image captured in the image.

Description

Technical Field

[0001] The present disclosure relates to a glass manufacturing method and a glass manufacturing apparatus.

Background Art

[0002] The glass manufacturing apparatus described in Patent Document 1 includes a float bath that houses molten metal, a lehr that gradually cools a glass ribbon formed in a strip shape on the molten metal, and a dross box provided between the float bath and the lehr. The glass manufacturing apparatus has a drape that partitions the upper space of the dross box in the conveyance direction of the glass ribbon. The same content is also disclosed in Patent Document 2.

[0003] The glass manufacturing apparatus described in Patent Document 1 includes a monitoring camera for managing the gap between the drape and the glass ribbon. The monitoring camera is provided outside the dross box and images the drape and the glass ribbon inside the dross box through a window of the dross box. The image processing apparatus measures the distance of the gap between the drape and the glass ribbon by processing the image captured by the monitoring camera.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, it has been studied to image a glass ribbon and an object with a camera and measure the distance between the glass ribbon and the object by processing the captured image. For example, if the camera is installed directly beside the glass ribbon when the glass ribbon is horizontal, the distance between the glass ribbon and an object above it can be measured.

[0006] However, depending on the angle of the camera's optical axis, it can be difficult to detect the position of the top surface of the glass ribbon in the image. For example, if the top surface of the glass ribbon appears as a surface rather than a line in the image, it is difficult to detect the position of the top surface of the glass ribbon.

[0007] Furthermore, a technique for quantifying the degree of surface waviness of a glass ribbon using images of the ribbon had not been previously investigated.

[0008] One aspect of this disclosure provides a technique for measuring the distance between a glass ribbon and an object.

[0009] Another aspect of this disclosure provides a technique for quantifying the degree of waviness on the surface of a glass ribbon. [Means for solving the problem]

[0010] A glass manufacturing method according to one aspect of the present disclosure comprises the following (A) to (D): (A) A strip-shaped glass ribbon is transported at a distance from the object. (B) A real image of one end of the object facing the glass ribbon and a mirror image of the same end reflected in the glass ribbon are captured by a camera. (C) The distance between the real image and the mirror image in the captured image is measured. (D) The distance between the glass ribbon and the object is calculated from the distance between the real image and the mirror image in the image.

[0011] A glass manufacturing method according to another aspect of the present disclosure comprises the following (E) to (G): (E) The surface of a strip-shaped glass ribbon is imaged with a camera. (F) In the image captured, the surface of the glass ribbon is divided into a plurality of detection regions, and the amount of color change of the glass ribbon within each detection region is detected. (G) The number of detection regions in which the detected amount of color change exceeds a threshold is counted. [Effects of the Invention]

[0012] According to one aspect of this disclosure, the distance between the glass ribbon and the object can be calculated by measuring the distance between the real image and the mirrored image of the object captured in the image.

[0013] According to another aspect of this disclosure, the degree of waviness on the surface of the glass ribbon can be quantified by counting the number of detection regions in which the amount of color change in the image exceeds a threshold. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a cross-sectional view showing a glass manufacturing apparatus according to one embodiment. [Figure 2] Figure 2 shows a camera and image processing device according to one embodiment. [Figure 3] Figure 3 shows an example of an image captured by the camera shown in Figure 2. [Figure 4] Figure 4 shows a modified example of a camera and image processing device. [Figure 5] Figure 5 shows an example of multiple detection areas and glass ribbon colors set by the detection unit in Figure 4. [Figure 6] Figure 6 shows an example of a detection region in Figure 5 where the amount of color change exceeds the threshold. [Figure 7] Figure 7 is a cross-sectional view showing a modified glass manufacturing apparatus. [Figure 8] Figure 8 shows a modified example of a camera and image processing device. [Figure 9] Figure 9 shows an example of an image captured by the camera shown in Figure 8. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted. In each drawing, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other, the X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction. The X-axis direction is the conveyance direction of the glass ribbon G, and the Y-axis direction is the width direction of the glass ribbon G. In the specification, "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0016] First, referring to FIG. 1, a glass manufacturing apparatus 1 according to an embodiment will be described. The glass manufacturing apparatus 1 includes, for example, a forming apparatus 2, a relay apparatus 3, and a slow cooling apparatus 5 in this order from the upstream side to the downstream side in the conveyance direction of the glass ribbon G. After being formed by the forming apparatus 2, the glass ribbon G is sent from the forming apparatus 2 to the slow cooling apparatus 5 by the relay apparatus 3 and is slowly cooled by the slow cooling apparatus 5. Thereafter, the glass ribbon G is cut by a processing apparatus (not shown). Thereby, a glass plate as a product is obtained.

[0017] The glass plate is, for example, non-alkali glass, aluminosilicate glass, borosilicate glass, or soda-lime glass. Non-alkali glass means glass that substantially does not contain alkali metal oxides such as Na2O and K2O. Here, substantially not containing alkali metal oxides means that the total content of alkali metal oxides is 0.1 mass% or less.

[0018] The use of the glass plate is not particularly limited. For example, it is a cover glass for a display (such as a liquid crystal display or an organic EL display). When the use of the glass plate is a cover glass, the glass plate is a glass for chemical strengthening. Different from non-alkali glass, the glass for chemical strengthening contains alkali metal oxides.

[0019] The thickness of the glass plate is selected according to its intended use. If the glass plate is used as cover glass for a display, the thickness is, for example, 0.1 mm to 5.0 mm. If the glass plate is used as a glass substrate for a display, the thickness is, for example, 0.1 mm to 0.7 mm. If the glass plate is used as a windshield for an automobile, the thickness is, for example, 0.2 mm to 3.0 mm.

[0020] Next, referring again to Figure 1, the molding apparatus 2, the relay apparatus 3, and the annealing apparatus 5 according to one embodiment will be described in this order. In this embodiment, the molding apparatus 2 forms the glass ribbon G by the float method, but the glass ribbon G may also be formed by the fusion method. The molding method is not particularly limited.

[0021] The molding apparatus 2 includes a molding furnace 21, which is a heat treatment furnace. The molding furnace 21 has a bathtub 211. The bathtub 211 contains molten metal M. For example, molten tin is used as the molten metal M. In addition to molten tin, molten tin alloys can also be used, and the molten metal M only needs to have a higher density than the molten glass. The molten glass is continuously supplied onto the molten metal M and is formed into a strip-shaped glass ribbon G using the smooth liquid surface of the molten metal M.

[0022] The molding furnace 21 is equipped with a ceiling 212 above the bathtub 211. The interior of the molding apparatus 2 is filled with a reducing gas and maintained at a pressure higher than atmospheric pressure to prevent oxidation of the molten metal M. The reducing gas is, for example, a mixture of nitrogen gas and hydrogen gas, containing 85% to 98.5% by volume of nitrogen gas and 1.5% to 15% by volume of hydrogen gas. The reducing gas is supplied through the joints between the bricks of the ceiling 212 and through holes in the ceiling 212.

[0023] The molding apparatus 2 includes a heater 22 for heating the glass ribbon G. The heater 22 is suspended, for example, from the ceiling 212 of the molding furnace 21 and heats the glass ribbon G as it passes below. The heater 22 is, for example, an electric heater and is heated by electric current. Multiple heaters 22 are arranged in a matrix in the transport direction and width direction of the glass ribbon G. By controlling the output of the multiple heaters 22, the temperature distribution of the glass ribbon G can be controlled, and the thickness distribution of the glass ribbon G can be controlled.

[0024] The relay device 3 comprises a dross box 31, which is a heat treatment furnace, and a lift-out roll 32. The lift-out roll 32 is positioned inside the dross box 31 and lifts the glass ribbon G from the molten metal M. Multiple lift-out rolls 32 are arranged at intervals in the direction of transport of the glass ribbon G (X-axis direction). The number of lift-out rolls 32 is not particularly limited. The lift-out rolls 32 are rotationally driven by a drive device (not shown), such as a motor, and the driving force transports the glass ribbon G diagonally upward. The axial direction of the lift-out roll 32 is the same as the width direction (Y-axis direction) of the glass ribbon G. The lift-out roll 32 is an example of the transport device described in the claims.

[0025] The relay device 3 may be equipped with a heater 33 on the ceiling of the dross box 31 to adjust the temperature of the glass ribbon G. The heater 33 may be provided not only above the glass ribbon G but also below it. In the relay device 3, the temperature of the glass ribbon G is preferably (Tg-50)℃ to (Tg+30)℃, with reference to the glass transition point Tg of the glass ribbon G.

[0026] The relay device 3 includes a drape 34 suspended from the ceiling of the drain box 31. The ceiling of the drain box 31 includes, for example, a hood 311 and an insulating material 312 placed on top of the hood 311. The drape 34 is suspended from the underside of the hood 311, penetrating a portion of the insulating material 312 and the hood 311. The drape 34 is a plate-shaped member made of a fire-resistant material such as steel or glass.

[0027] The drape 34 is a partition wall that divides the upper space of the draw box 31 into multiple spaces in the direction of transport of the glass ribbon G (X-axis direction). The upper space of the draw box 31 is the space above the glass ribbon G. The drape 34 is positioned, for example, directly above the rotation centerline of each lift-out roll 32. The drape 34 extends in the axial direction (Y-axis direction) of each lift-out roll 32.

[0028] The drape 34 prevents oxygen gas from entering the dross box 31 from the annealing furnace 51 (described later), thereby suppressing an increase in oxygen concentration within the dross box 31. This suppresses the combustion of hydrogen gas flowing from the molding furnace 21 into the dross box 31. As a result, temperature fluctuations and localized heating of the glass ribbon G due to hydrogen gas combustion can be suppressed. The drape 34 forms a gap between itself and the upper surface of the glass ribbon G so as not to obstruct the transport of the glass ribbon G.

[0029] The annealing device 5 comprises an annealing furnace 51, which is a heat treatment furnace, and layer rolls 52. The layer rolls 52 are positioned inside the annealing furnace 51 and transport the glass ribbon G in the longitudinal direction (X-axis direction) of the glass ribbon G. Multiple layer rolls 52 are provided at intervals in the transport direction of the glass ribbon G. The number of layer rolls 52 is not particularly limited. The layer rolls 52 are rotationally driven by a drive device (not shown), such as a motor, and the driving force transports the glass ribbon G in the horizontal direction (X-axis direction). The axial direction of the layer rolls 52 is the same as the width direction (Y-axis direction) of the glass ribbon G.

[0030] The annealing device 5 slowly cools the glass ribbon G to a temperature below the glass strain point while conveying it with the layer roll 52. The annealing device 5 is equipped with an internal heater (not shown) to adjust the temperature of the glass ribbon G.

[0031] Next, with reference to Figures 2 and 3, a camera 6 and an image processing device 7 according to one embodiment will be described. The glass manufacturing apparatus 1 comprises a camera 6 and an image processing device 7 that processes an image P1 captured by the camera 6. The camera 6 captures an image of a strip-shaped glass ribbon G and an object that forms a gap between the glass ribbon G and the object. The object is not particularly limited, but in this embodiment it is a drape 34. The image processing device 7 measures the distance L1 between the upper surface of the glass ribbon G and the lower end 341 of the drape 34 by processing the image P1 captured by the camera 6. The image processing device 7 may measure the distance L1 in the image P1, or it may measure the distance L1 in real space.

[0032] Camera 6 is installed, for example, on the outside of a dross box 31, which is a heat treatment furnace, and images the glass ribbon G and drape 34 through a window in the side wall provided at one end of the dross box 31 in the Y-axis direction. A light source (not shown) may be provided to illuminate the object to be imaged. By illuminating the object to be imaged with light, a clear image P1 can be obtained. The light source illuminates the glass ribbon G and drape 34 through a window in the side wall provided at the other end of the dross box 31 in the Y-axis direction.

[0033] Incidentally, depending on the angle of the optical axis 61 of the camera 6, it can be difficult to detect the position of the top surface of the glass ribbon G as it appears in image P1. For example, if the top surface of the glass ribbon G appears as a surface rather than a line in image P1, it can be difficult to detect the position of the top surface of the glass ribbon G.

[0034] For example, if the optical axis 61 of the camera 6 is positioned at an angle to the upper surface of the horizontal glass ribbon G, a mirror image of the lower end 341 of the drape 34 is reflected on the upper surface of the glass ribbon G. The technology of this disclosure uses the mirror image reflected on the upper surface of the glass ribbon G to measure the distance L1 between the upper surface of the glass ribbon G and the lower end 341 of the drape 34.

[0035] As shown in Figure 3, the image P1 captured by the camera 6 includes a real image 341A and a mirror image 341B of the lower end 341 of the drape 34. The lower end 341 of the drape 34 is an example of one end facing the glass ribbon G of the object described in the claims. The camera 6 includes an image sensor such as a CCD or CMOS, and transmits the image P1 captured by the image sensor to the image processing device 7.

[0036] The image processing device 7 is, for example, a computer and comprises a CPU (Central Processing Unit) and a storage medium such as memory. The storage medium stores programs that control various processes performed by the image processing device 7. The image processing device 7 controls its operation by causing the CPU to execute the programs stored in the storage medium.

[0037] As shown in Figure 2, the image processing device 7 includes, for example, a measurement unit 71 and a calculation unit 72. The measurement unit 71 measures the distance L2 (see Figure 3) between the real image 341A and its mirror image 341B in the image P1. The magnitude of the distance L2 is expressed, for example, by the number of pixels in the image P1. The greater the distance from the camera 6 to the object, the smaller the size of the object appears in the image P1. The measurement unit 71 measures the distance L2 at a specific position in the image P1.

[0038] The calculation unit 72 calculates the distance L1 between the upper surface of the glass ribbon G and the lower end 341 of the drape 34 from the distance L2 between the real image 341A and the mirror image 341B projected in image P1. For example, the distance L1 projected in image P1 is half of the distance L2 projected in image P1. The product of the distance L1 projected in image P1 and the proportionality constant is the actual distance L1 (distance L1 in real space). The proportionality constant is mainly determined by the distance from the camera 6 to the measurement point of distance L1 and can be determined in advance through experiments or other means. The magnitude of the distance L1 calculated by the calculation unit 72 may be expressed in terms of the number of pixels in image P1, or in a common unit of length such as mm. As will be described later, the calculation unit 72 may also determine the proportionality constant by referring to a reference distance L0 in order to improve the measurement accuracy of the distance L1.

[0039] Camera 6 may capture images of multiple reference points SP1 and SP2 indicating a reference distance L0. The captured image P1 includes the real image 341A and mirror image 341B of the lower end 341 of the drape 34, as well as the multiple reference points SP1 and SP2. Image P1 may include either the real image or the mirror image of the reference points SP1 and SP2, or both.

[0040] The reference points SP1 and SP2 are not particularly limited, but for example, bolts or nuts connecting multiple plates that make up the drape 34 can be used. As shown in Figure 2, the reference points SP1 and SP2 are positioned at a reference distance L0 in a direction perpendicular to the surface of the glass ribbon G facing the drape 34 (for example, the top surface).

[0041] The measurement unit 71 measures the reference distance L0 that appears in the image P1. The magnitude of the reference distance L0 that appears in the image P1 is expressed, for example, in terms of the number of pixels. The calculation unit 72 calculates the distance L1 between the upper surface of the glass ribbon G and the lower end 341 of the drape 34 from the distance L2 between the real image 341A and the mirror image 341B that appear in the image P1, and the reference distance L0 that appears in the image P1. The calculation unit 72 may calculate the distance L1 in the image P1, or it may calculate the distance L1 in real space.

[0042] By referencing the reference distance L0 in image P1 when calculating the distance L1 in image P1, even if the reference distance L0 in image P1 fluctuates due to disturbances, the absolute value of distance L1 can be accurately calculated by calculating the relative value of distance L1 with respect to the reference distance L0. Furthermore, by calculating the ratio of the number of pixels at the reference distance L0 in image P1 to the reference distance L0 in real space, the proportionality constant when converting the number of pixels to distance in real space can be calculated.

[0043] As described above, the greater the distance from camera 6 to the object, the smaller the size of the object appears in image P1. If image P1 contains multiple sets of reference points SP1 and SP2 that indicate a reference distance L0, the calculation unit 72 may measure the distance L2 on a straight line connecting each set of reference points SP1 and SP2 in image P1. By using multiple sets of reference points SP1 and SP2, the measurement accuracy of distance L1 can be improved.

[0044] Next, with reference to Figures 4 to 6, a modified example of the camera 6 and image processing device 7 will be described. The glass manufacturing apparatus 1 comprises a camera 6 and an image processing device 7 that processes the image P2 captured by the camera 6. The camera 6 images the surface of the strip-shaped glass ribbon G. The camera 6 images at least the portion of the glass ribbon G that will become the product, for example, the central part in the width direction of the glass ribbon G. The image processing device 7 quantifies the degree of waviness on the surface of the glass ribbon G by processing the image P2 captured by the camera 6.

[0045] Camera 6 is installed, for example, on the outside of the molding furnace 21, which is a heat treatment furnace, and images the surface of the glass ribbon G through a window in the side wall provided at one end of the molding furnace 21 in the Y-axis direction. A light source (not shown) may be provided to irradiate the object to be imaged with light. By irradiating the object to be imaged with light, a clear image P2 can be obtained. The light source irradiates the surface of the glass ribbon G with light through a window in the side wall provided at the other end of the molding furnace 21 in the Y-axis direction.

[0046] If the glass ribbon G is formed using the float method, the glass ribbon G is transported horizontally within the molding furnace 21. In contrast, if the glass ribbon G is formed using the fusion method, the glass ribbon G is transported vertically downward within the molding furnace 21. In either case, the camera 6 only needs to image the main surface of the glass ribbon G.

[0047] The installation position of camera 6 is not particularly limited. Camera 6 may image the surface of the glass ribbon G through the window of the dross box 31 or the annealing furnace 51, rather than through the molding furnace 21. In both the float method and the fusion method, the glass ribbon G is transported horizontally within the annealing furnace 51. Camera 6 includes an image sensor such as a CCD or CMOS, and transmits the image P2 captured by the image sensor to the image processing device 7.

[0048] As shown in Figure 4, the image processing device 7 includes, for example, a detection unit 73, a counting unit 74, and a setting unit 75. As shown in Figure 5, the detection unit 73 divides the surface of the glass ribbon G into multiple detection regions A1 to An in the image P2 captured by the camera 6, and detects the amount of color change of the glass ribbon G within each detection region A1 to An. Figure 5 shows an example of the color of the glass ribbon G, where the brightness of the color differs between region B and the region outside of region B.

[0049] Each detection region A1 to An preferably has the same dimensions and shape. While the shape of each detection region A1 to An is rectangular in Figure 5, it may also be triangular or hexagonal. Rectangles include squares. Each detection region A1 to An contains multiple pixels (e.g., 8x8 pixels, totaling 64 pixels) not shown. The size of each detection region A1 to An is set as appropriate.

[0050] The amount of color change in each detection region A1 to An is expressed, for example, as the difference between the maximum and minimum values ​​of the color of multiple pixels (e.g., 64 pixels), the standard deviation, or the variance. Color is represented, for example, as density in grayscale, i.e., brightness. If image P2 is in color, a conversion from color to grayscale is performed. A common conversion method is used. Note that color may be represented by color space coordinates, or it may remain in color.

[0051] The counting unit 74 counts the number of detection regions where the amount of color change detected by the detection unit 73 exceeds a threshold. Region C shown in Figure 6 indicates a detection region in image P2 of Figure 5 where the amount of color change exceeds the threshold. When surface undulations exist on the surface of the glass ribbon G, the color changes beyond the threshold at the contour line of the surface undulations. Therefore, by counting the number of detection regions where the amount of color change exceeds the threshold, the degree of surface undulation on the glass ribbon G can be quantified.

[0052] Incidentally, the color of the glass ribbon G may change due to disturbances other than surface undulation. Therefore, the setting unit 75 may set an area in a part of image P2 where counting by the counting unit 74 is not performed. The area to be set is the area where the color of the glass ribbon G changes due to disturbances, and this area is determined in advance by experiment or simulation.

[0053] The counting unit 74 counts the number of detection regions outside the area set by the setting unit 75 where the amount of color change exceeds a threshold. By using the setting unit 75, disturbances can be eliminated, and the detection accuracy of surface undulation can be improved. When the setting unit 75 is used, the detection unit 73 detects the amount of color change in each detection region outside the area set by the setting unit 75.

[0054] Next, with reference to Figure 7, a modified glass manufacturing apparatus 1 will be described. The glass manufacturing apparatus 1 comprises a dross box 31 and an annealing furnace 51. The dross box 31 is the first heat treatment furnace, and the annealing furnace 51 is the second heat treatment furnace. After the lift-out roll 32 horizontally conveys the glass ribbon G inside the dross box 31, the layer roll 52 horizontally conveys the glass ribbon G inside the annealing furnace 51.

[0055] The glass manufacturing apparatus 1 is equipped with a partition wall 53. The partition wall 53 separates the space below the glass ribbon G in the direction of transport of the glass ribbon G at the boundary between the dross box 31 and the annealing furnace 51. The internal space of the dross box 31 is a reducing atmosphere, and the internal space of the annealing furnace 51 is an atmospheric atmosphere. The partition wall 53 suppresses the inflow of reducing gas from the internal space of the dross box 31 into the internal space of the annealing furnace 51, and maintains an atmospheric atmosphere in the internal space of the annealing furnace 51.

[0056] The glass manufacturing apparatus 1 may include a lifting mechanism (not shown) for raising and lowering the partition wall 53. By raising and lowering the partition wall 53, the distance L3 (see Figure 8) between the upper end of the partition wall 53 and the lower surface of the glass ribbon G can be changed. The smaller the distance L3, the more effectively the passage of reducing gas can be suppressed, but the easier it becomes for the partition wall 53 and the glass ribbon G to come into contact. The distance L3 is set taking into consideration factors such as the deflection due to the weight of the glass ribbon G.

[0057] In this modified example, the partition wall 53 is provided separately from the dross box 31 and the annealing furnace 51, as shown in Figure 7, but it may also be provided as part of the dross box 31 or as part of the annealing furnace 51.

[0058] Next, with reference to Figures 8 and 9, a modified example of the camera 6 and image processing device 7 will be described. The glass manufacturing apparatus 1 comprises a camera 6 and an image processing device 7 that processes the image P3 captured by the camera 6. The camera 6 captures a strip-shaped glass ribbon G and an object that forms a gap between the glass ribbon G and the object. The object is not particularly limited, but in this modified example it is a partition wall 53. The image processing device 7 measures the distance L3 between the lower surface of the glass ribbon G and the upper end 531 of the partition wall 53 by processing the image P3 captured by the camera 6. The image processing device 7 may measure the distance L3 in the image P3, or it may measure the distance L3 in real space.

[0059] Camera 6 is installed, for example, on the outside of the annealing furnace 51 and images the glass ribbon G and partition wall 53 through a window in the side wall provided at one end of the annealing furnace 51 in the Y-axis direction. A light source (not shown) may be provided to illuminate the object to be imaged. By illuminating the object to be imaged with light, a clear image P3 can be obtained. The light source illuminates the glass ribbon G and partition wall 53 through a window in the side wall provided at the other end of the annealing furnace 51 in the Y-axis direction.

[0060] Incidentally, depending on the angle of the optical axis 61 of camera 6, it can be difficult to detect the position of the underside of the glass ribbon G as it appears in image P3. For example, if the underside of the glass ribbon G appears as a surface rather than a line in image P3, it can be difficult to detect the position of the underside of the glass ribbon G.

[0061] For example, if the optical axis 61 of the camera 6 is installed at an angle to the lower surface of the horizontal glass ribbon G, a mirror image of the upper end 531 of the partition wall 53 is reflected on the lower surface of the glass ribbon G. The technology of this disclosure uses the mirror image reflected on the lower surface of the glass ribbon G to measure the distance L3 between the lower surface of the glass ribbon G and the upper end 531 of the partition wall 53.

[0062] As shown in Figure 9, the image P3 captured by the camera 6 includes a real image 531A and a mirror image 531B of the upper end 531 of the partition wall 53. The upper end 531 of the partition wall 53 is an example of one end facing the glass ribbon G of the object described in the claims. The camera 6 includes an image sensor such as a CCD or CMOS, and transmits the image P3 captured by the image sensor to the image processing device 7.

[0063] As shown in Figure 8, the image processing device 7 includes, for example, a measurement unit 71 and a calculation unit 72. The measurement unit 71 measures the distance L4 (see Figure 9) between the real image 531A and its mirror image 531B in the image P3. The magnitude of the distance L4 is expressed, for example, by the number of pixels in the image P3. The greater the distance from the camera 6 to the object, the smaller the size of the object in the image P3. The measurement unit 71 measures the distance L4 at a specific position in the image P3.

[0064] The calculation unit 72 calculates the distance L3 between the lower surface of the glass ribbon G and the upper end 531 of the partition wall 53 from the distance L4 between the real image 531A and the mirror image 531B projected in image P3. For example, the distance L3 projected in image P3 is half of the distance L4 projected in image P3. The product of the distance L3 projected in image P3 and the proportionality constant is the distance L3 in real space. The proportionality constant is mainly determined by the distance from the camera 6 to the measurement point of distance L3, and can be determined in advance through experiments or other means. The magnitude of the distance L3 calculated by the calculation unit 72 may be expressed in terms of the number of pixels in image P3, or in a common unit of length such as mm. As will be described later, the calculation unit 72 may also determine the proportionality constant by referring to a reference distance L0 in order to improve the measurement accuracy of the distance L3.

[0065] Camera 6 may capture images of multiple reference points SP3 and SP4 that indicate a reference distance L0. The captured image P3 includes the real image 531A and mirror image 531B of the upper end 531 of the partition wall 53, as well as the multiple reference points SP3 and SP4. Image P3 may include either the real image or the mirror image of the reference points SP3 and SP4, or both.

[0066] Reference point SP3 is, for example, a point on the first laser beam LB1, and reference point SP4 is a point on the second laser beam LB2. The first laser beam LB1 and the second laser beam LB2 are irradiated from the laser irradiator 8 onto the object (e.g., partition wall 53) parallel to each other. The direction of irradiation is parallel to the lower surface of the glass ribbon G, but it may be inclined or perpendicular. It is sufficient that the first laser beam LB1 and the second laser beam LB2 are parallel to each other. The reference distance L0 is the distance between the first laser beam LB1 and the second laser beam LB2.

[0067] By irradiating an object with two parallel laser beams, a first laser beam LB1 and a second laser beam LB2, reference points SP3 and SP4 can be created on the object. This is particularly effective when the object does not have bolts or nuts that can serve as reference points SP3 and SP4. Note that bolts or nuts may be used as reference points SP3 and SP4 on the partition wall 53. Furthermore, while the object irradiated with the first laser beam LB1 and the second laser beam LB2 is the partition wall 53 in this modified example, it may also be a drape 34.

[0068] The measurement unit 71 measures the reference distance L0 as it appears in image P3. The magnitude of the reference distance L0 as it appears in image P3 is expressed, for example, in terms of the number of pixels. The calculation unit 72 calculates the distance L3 between the lower surface of the glass ribbon G and the upper end 531 of the partition wall 53 from the distance L4 between the real image 531A and the mirror image 531B as they appear in image P3, and the reference distance L0 as it appears in image P3. The calculation unit 72 may calculate the distance L3 in image P3, or it may calculate the distance L3 in real space.

[0069] By referencing the reference distance L0 in image P3 when calculating the distance L3 in image P3, even if the reference distance L0 in image P3 fluctuates due to disturbances, the absolute value of distance L3 can be accurately calculated by calculating the relative value of distance L3 with respect to the reference distance L0. Furthermore, by calculating the ratio of the number of pixels at reference distance L0 in image P3 to the reference distance L0 in real space, the proportionality constant when converting the number of pixels to distance in real space can be calculated.

[0070] As described above, the greater the distance from camera 6 to the object, the smaller the size of the object appears in image P3. If image P3 contains multiple sets of reference points SP3 and SP4 that indicate the reference distance L0, the calculation unit 72 may measure the distance L4 on a straight line connecting each set of reference points SP3 and SP4 in image P3. By using multiple sets of reference points SP3 and SP4, the measurement accuracy of the distance L3 can be improved.

[0071] The following additional information is disclosed regarding the above embodiments, etc. [Note 1] Transporting a strip-shaped glass ribbon while maintaining a distance from the object, The camera captures the real image of one end of the object facing the glass ribbon and the mirror image of the same end of the object reflected in the glass ribbon. The distance between the real image and the mirror image captured in the image is measured, The distance between the glass ribbon and the object is calculated from the distance between the real image and the mirror image in the aforementioned image, A glass manufacturing method having the following characteristics. [Note 2] The camera captures images of multiple reference points indicating the reference distance, To measure the reference distance shown in the aforementioned image, The distance between the glass ribbon and the object is calculated from the distance between the real image and the mirror image in the aforementioned image, and the reference distance in the aforementioned image. A glass manufacturing method as described in Appendix 1, comprising the characteristics of the glass manufacturing method described in Appendix 1. [Note 3] The method involves irradiating the object with a first laser beam and a second laser beam that are parallel to each other. The multiple reference points are one point of the first laser beam and one point of the second laser beam, The glass manufacturing method according to Appendix 2, wherein the reference distance is the distance between the first laser beam and the second laser beam. [Note 4] This includes horizontally transporting the glass ribbon inside the heat treatment furnace, The glass manufacturing method according to any one of the appendices 1 to 3, wherein the object is a partition wall that divides the upper space of the heat treatment furnace in the direction of transport of the glass ribbon. [Note 5] This includes transporting the glass ribbon horizontally inside a first heat treatment furnace, and then transporting the glass ribbon horizontally inside a second heat treatment furnace. The glass manufacturing method according to any one of the appendices 1 to 3, wherein the object is a partition wall that separates the space below the glass ribbon in the direction of transport of the glass ribbon at the boundary between the first heat treatment furnace and the second heat treatment furnace. [Note 6] A glass manufacturing method according to any one of the appendices 1 to 5, comprising forming the glass ribbon by the float method or the fusion method. [Note 7] The surface of a strip-shaped glass ribbon is imaged with a camera, In the captured image, the surface of the glass ribbon is divided into a plurality of detection regions, and the amount of color change of the glass ribbon within each detection region is detected. The number of detected regions where the detected amount of color change exceeds a threshold is counted, A glass manufacturing method having the following characteristics. [Note 8] The glass manufacturing method according to Appendix 7, wherein a part of the aforementioned image is set to an area where the counting is not performed. [Note 9] A glass manufacturing method according to Appendix 7 or 8, comprising forming the glass ribbon by the float method or the fusion method. [Note 10] A conveying device that transports a strip-shaped glass ribbon at a distance from the object, A camera that captures a real image of one end of the object facing the glass ribbon and a mirror image of the same end of the object reflected in the glass ribbon, An image processing device that processes images captured by the aforementioned camera, Equipped with, The image processing apparatus comprises a measuring unit for measuring the distance between the real image and the mirror image in the image, and a calculation unit for calculating the distance between the glass ribbon and the object from the distance between the real image and the mirror image in the image, wherein the apparatus is a glass manufacturing apparatus. [Note 11] The camera captures images of multiple reference points indicating a reference distance, The measurement unit measures the reference distance captured in the image, The glass manufacturing apparatus according to Appendix 10, wherein the calculation unit calculates the distance between the glass ribbon and the object from the distance between the real image and the mirror image in the image and the reference distance in the image. [Note 12] The device comprises a laser irradiator that irradiates the object with a first laser beam and a second laser beam that are parallel to each other, The multiple reference points are one point of the first laser beam and one point of the second laser beam, The glass manufacturing apparatus as described in Appendix 11, wherein the reference distance is the distance between the first laser beam and the second laser beam. [Note 13] The conveying device conveys the glass ribbon horizontally inside the heat treatment furnace. The glass manufacturing apparatus according to any one of appendices 10 to 12, wherein the object is a partition wall that divides the upper space of the heat treatment furnace in the direction of transport of the glass ribbon. [Note 14] The conveying device conveys the glass ribbon horizontally inside the first heat treatment furnace, and then conveys the glass ribbon horizontally inside the second heat treatment furnace. The glass manufacturing apparatus according to any one of appendices 10 to 12, wherein the object is a partition wall that separates the space below the glass ribbon in the direction of transport of the glass ribbon at the boundary between the first heat treatment furnace and the second heat treatment furnace. [Note 15] A camera that images the surface of a strip-shaped glass ribbon, An image processing device that processes images captured by the aforementioned camera, Equipped with, The image processing apparatus comprises a glass manufacturing apparatus that divides the surface of the glass ribbon into a plurality of detection regions in the captured image, a detection unit that detects the amount of color change of the glass ribbon within each detection region, and a counting unit that counts the number of detection regions in which the detected amount of color change exceeds a threshold. [Note 16] The glass manufacturing apparatus according to Appendix 15, wherein the image processing apparatus has a setting unit that sets an area in a part of the captured image in which counting is not performed by the counting unit.

[0072] The glass manufacturing method and glass manufacturing apparatus described above are not limited to the embodiments described herein. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally fall within the technical scope of this disclosure. [Explanation of Symbols]

[0073] 1. Glass manufacturing equipment 6 cameras 7 Image Processing Device 71 Measurement Unit 72 Calculation Unit 73 Detection unit 74 Count section 75 Settings Section 34. Drapes (objects) 341A Real image 341B Mirror image G Glass Ribbon

Claims

1. The surface of a strip-shaped glass ribbon is imaged with a camera, In the captured image, the surface of the glass ribbon is divided into a plurality of detection regions, and the amount of color change of the glass ribbon within each detection region is detected. The number of detected regions where the detected amount of color change exceeds a threshold is counted, A glass manufacturing method having the following characteristics.

2. The glass manufacturing method according to claim 1, further comprising setting an area in the aforementioned image where the counting is not performed.

3. A glass manufacturing method according to claim 1 or 2, comprising forming the glass ribbon by a float method or a fusion method.

4. A camera that images the surface of a strip-shaped glass ribbon, An image processing device that processes images captured by the aforementioned camera, Equipped with, The image processing apparatus comprises a glass manufacturing apparatus that divides the surface of the glass ribbon into a plurality of detection regions in the captured image, a detection unit that detects the amount of color change of the glass ribbon within each detection region, and a counting unit that counts the number of detection regions in which the detected amount of color change exceeds a threshold.

5. The glass manufacturing apparatus according to claim 4, wherein the image processing apparatus has a setting unit for setting an area in a part of the captured image in which the counting unit does not perform counting.

Images