Glass manufacturing method and glass manufacturing apparatus

Abstract

This invention provides a technique for measuring the temperature of a glass ribbon diagonally below a window in the side wall of a heat treatment furnace that houses a horizontal glass ribbon, when forming a glass ribbon using the float method. [Solution] The glass manufacturing method comprises rotating a top roll while pressing down on the widthwise end of the upper surface of a horizontal strip-shaped glass ribbon with the top roll. The glass manufacturing method comprises measuring the temperature of the widthwise end of the glass ribbon diagonally below the window through a window in the side wall of a heat treatment furnace that houses the horizontal glass ribbon using a radiation thermometer.

Description

Technical Field

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

Background Art

[0002] As a glass manufacturing method, the float method is known. In the float method, molten glass is continuously supplied onto the surface of molten metal, and the molten glass is formed into a ribbon shape on the surface of the molten metal. The glass formed into a ribbon shape is also called a glass ribbon. The glass ribbon gradually cools and solidifies while flowing in a predetermined direction on the surface of the molten metal.

[0003] The thickness of the glass ribbon becomes an equilibrium thickness determined by the balance between gravity and surface tension unless an external force is applied to the glass ribbon. To form a glass ribbon thinner than the equilibrium thickness, top rolls are used (see, for example, Patent Document 1). The top rolls are provided on both sides in the width direction of the glass ribbon and apply tension in the width direction of the glass ribbon.

[0004] As another glass manufacturing method, the fusion method is known (see, for example, Patent Document 2). In the fusion method, the molten glass overflowing from both the left and right sides of the trough is joined at the lower end of the trough to form a ribbon-shaped glass ribbon. In Patent Document 2, a radiation thermometer is installed in front of the glass ribbon to measure the temperature of the glass ribbon.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] A radiation thermometer has multiple light-receiving elements. These elements are arranged in a matrix. The path of light received by each light-receiving element is different for each element. Each light-receiving element transmits a signal corresponding to the intensity of the received light to an image processing device. The image processing device creates a temperature distribution map corresponding to the intensity of light received by each light-receiving element.

[0007] In the radiation thermometer described in Patent Document 2, the optical axis of each light-receiving element is positioned perpendicular to the main surface of the glass ribbon. In this case, each light-receiving element receives the light emitted by the glass ribbon, but does not receive the light emitted by the surrounding material of the glass ribbon and reflected by the glass ribbon. Therefore, it is possible to measure the temperature of the glass ribbon, rather than the temperature of the surrounding material. Here, the surrounding material is, for example, a heater or a brick.

[0008] In the float method, unlike the fusion method described in Patent Document 2, the glass ribbon is kept horizontal. Therefore, in order to install the radiation thermometer so that the optical axis of each light-receiving element of the radiation thermometer is perpendicular to the main plane of the glass ribbon, it is necessary to open a window in the ceiling of the heat treatment furnace.

[0009] One embodiment of the present disclosure provides a technique for measuring the temperature of a glass ribbon diagonally below a window in a heat treatment furnace that houses a horizontal glass ribbon, when forming a glass ribbon by the float method. [Means for solving the problem]

[0010] A glass manufacturing method according to one embodiment of the present disclosure comprises rotating a top roll while pressing down on the widthwise end of the upper surface of a horizontal strip-shaped glass ribbon with the top roll. The glass manufacturing method comprises measuring the temperature of the widthwise end of the glass ribbon diagonally below the window through a window in the side wall of a heat treatment furnace containing the horizontal glass ribbon using a radiation thermometer. [Effects of the Invention]

[0011] According to one embodiment of the present disclosure, when forming a glass ribbon by the float method, the temperature of the glass ribbon diagonally below the window can be measured using a window in the side wall of a heat treatment furnace that houses a horizontal glass ribbon. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a cross-sectional view showing a glass manufacturing apparatus according to one embodiment. [Figure 2] Figure 2 is a cross-sectional view showing an example of a molding apparatus. [Figure 3] Figure 3 is a plan view showing an example of the arrangement of the top rolls. [Figure 4] Figure 4 is a cross-sectional view showing an example of a radiation thermometer. [Figure 5] Figure 5 is a cross-sectional view showing an example of a temperature distribution map. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, identical or similar components are denoted by the same reference numerals, and their descriptions may be omitted. In each drawing, the X-axis, Y-axis, and Z-axis directions are perpendicular to each other, the X-axis and Y-axis directions are horizontal, and the Z-axis direction is vertical. The X-axis direction is the transport direction of the glass ribbon GR, and the Y-axis direction is the width direction of the glass ribbon GR. In this specification, the "~" indicating a numerical range means that the numbers written before and after it are included as the lower and upper limits. The numerical range includes the rounded range.

[0014] First, with reference to Figure 1, a glass manufacturing apparatus 1 according to one embodiment will be described. The glass manufacturing apparatus 1 manufactures glass plates by the float process. The glass plates are, for example, alkali-free glass, aluminosilicate glass, borosilicate glass, or soda-lime glass. Alkali-free glass means glass that does not substantially contain alkali metal oxides such as Na2O and K2O. Here, substantially free of alkali metal oxides means that the total amount of alkali metal oxides contained is 0.1% by mass or less.

[0015] The uses of glass plates are not particularly limited, but one example is as cover glass for displays (e.g., liquid crystal displays or organic EL displays). When the glass plate is used as cover glass, it is chemically strengthened glass. Unlike alkali-free glass, chemically strengthened glass contains alkali metal oxides.

[0016] 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.

[0017] Glass manufacturing apparatus 1 comprises, for example, a melting apparatus 2, a molding apparatus 3, and an annealing apparatus 4, in this order.

[0018] The melting apparatus 2 includes, for example, a melting furnace 21 for containing molten glass G, and a burner 22 that forms a flame above the molten glass G contained in the melting furnace 21. The glass raw material introduced into the melting furnace 21 gradually melts into the molten glass G by radiant heat from the flame formed by the burner 22. The molten glass G is continuously transported from the melting apparatus 2 to the molding apparatus 3. The heat source is not limited to the burner 22, but may be an electric heater or electrodes, etc. The electrodes generate heat in the molten glass G by passing an electric current through it.

[0019] The forming device 3 includes a forming furnace 31, and melts the molten glass G into a desired shape inside the forming furnace 31. The forming furnace 31 is an example of a heat treatment furnace. The forming furnace 31 has, for example, a bath 311. The bath 311 houses the molten metal M. As the molten metal M, for example, molten tin is used. In addition to molten tin, a molten tin alloy or the like can also be used, and the molten metal M only needs to have a density higher than that of the molten glass G. The molten glass G is continuously supplied onto the molten metal M, and is formed into a strip-shaped glass ribbon GR by using the smooth liquid surface of the molten metal M.

[0020] The forming furnace 31 has a ceiling 312 above the bath 311. The inside of the forming furnace 31 is filled with a reducing gas to prevent oxidation of the molten metal M, and is maintained at a pressure higher than the atmospheric pressure. The reducing gas is, for example, a mixed gas of nitrogen gas and hydrogen gas, and contains 85 vol% to 98.5 vol% of nitrogen gas and 1.5 vol% to 15 vol% of hydrogen gas. The reducing gas is supplied from the joints between the bricks of the ceiling 312 and the holes of the ceiling 312.

[0021] The forming device 3 includes a heater 32 that heats the glass ribbon GR. The heater 32 is, for example, suspended from the ceiling 312 of the forming furnace 31, and heats the glass ribbon GR passing below. The heater 32 is, for example, an electric heater and is heated by energization. A plurality of heaters 32 are arranged in a matrix in the conveying direction and width direction of the glass ribbon GR. By controlling the outputs of the plurality of heaters 32, the temperature distribution of the glass ribbon GR can be controlled, and the plate thickness distribution of the glass ribbon GR can be controlled.

[0022] The slow cooling device 4 slowly cools the glass ribbon GR formed by the forming device 3. The slow cooling device 4 has, for example, a heat treatment furnace and conveying rolls that convey the glass article in a desired direction inside the heat treatment furnace. The conveying rolls are, for example, arranged in a plurality at intervals in the horizontal direction. The glass ribbon GR is slowly cooled while being conveyed from the inlet of the heat treatment furnace to the outlet of the heat treatment furnace. By slowly cooling the glass ribbon GR, the residual strain can be reduced.

[0023] The slow cooling device 4 comprises a dross box 41 and a lift-out roll 42. The dross box 41 is an example of a heat treatment furnace. The lift-out roll 42 is positioned inside the dross box 41 and lifts the glass ribbon GR from the molten metal M. The lift-out roll 42 is an example of a conveying roll. Multiple lift-out rolls 42 are arranged at intervals in the conveying direction (X-axis direction) of the glass ribbon GR. The number of lift-out rolls 42 is not particularly limited. The lift-out roll 42 is rotationally driven by a drive device such as a motor (not shown), and the driving force conveys the glass ribbon GR diagonally upward. The axial direction of the lift-out roll 42 is the same as the width direction (Y-axis direction) of the glass ribbon GR.

[0024] The slow cooling device 4 may be equipped with a heater (not shown) on the ceiling of the dross box 41 to adjust the temperature of the glass ribbon GR. The heater may be provided not only above the glass ribbon GR but also below it. Inside the dross box 41, the temperature of the glass ribbon GR is preferably (Tg-50)°C to (Tg+30)°C, with respect to the glass transition point Tg of the glass ribbon GR.

[0025] The annealing device 4 comprises an annealing furnace 45 and layer rolls 46. The annealing furnace 45 is located downstream of the dross box 41. The annealing furnace 45 is an example of a heat treatment furnace. The layer rolls 46 are located inside the annealing furnace 45 and transport the glass ribbon GR in the longitudinal direction (X-axis direction) of the glass ribbon GR. The layer rolls 46 are an example of a transport roll. Multiple layer rolls 46 are provided at intervals in the transport direction of the glass ribbon GR. The number of layer rolls 46 is not particularly limited. The layer rolls 46 are rotationally driven by a drive device such as a motor (not shown), and the driving force transports the glass ribbon GR in the horizontal direction (X-axis direction). The axial direction of the layer rolls 46 is the same as the width direction (Y-axis direction) of the glass ribbon GR.

[0026] The annealing device 4 slowly cools the glass ribbon GR to a temperature below the strain point of the glass while conveying it with a layer roll 46. The annealing device 4 may be equipped with a heater (not shown) inside the annealing furnace 45 to adjust the temperature of the glass ribbon GR.

[0027] Next, with reference to Figure 2, the molding apparatus 3 will be described in detail. The molding apparatus 3 includes a molding furnace 31 that houses a horizontal glass ribbon GR. The molding furnace 31 includes, for example, a bathtub 311, a ceiling 312, and side walls 313. The side walls 313 are located above the bathtub 311. The side walls 313 have a brick layer 314 and a metal layer 315 located outside the brick layer 314. The side walls 313 are located on both sides of the glass ribbon GR in the width direction (positive Y-axis side and negative Y-axis side).

[0028] The molding apparatus 3 includes a top roll 33. The top roll 33 is inserted into the molding furnace 31 through a gap formed between the bathtub 311 and the side wall 313. The top roll 33 feeds out the glass ribbon GR by rotating while pressing down on the widthwise end of the upper surface of the glass ribbon GR. The upper surface of the glass ribbon GR is sometimes called the top surface. The lower surface of the glass ribbon GR is sometimes called the bottom surface.

[0029] As shown in Figure 3, a pair of top rolls 33 are provided on both sides of the glass ribbon GR in the width direction. The pair of top rolls 33 suppress the shrinkage of the glass ribbon GR in the width direction. The thickness of the glass ribbon GR can be made thinner than the equilibrium thickness. Multiple pairs of top rolls 33 are provided at intervals in the flow direction (X-axis direction) of the glass ribbon GR. The glass ribbon GR flows on the liquid surface of the molten metal M and is gradually cooled and solidified.

[0030] Next, an example of temperature measurement of the glass ribbon GR will be described with reference to Figures 4 and 5. As shown in Figure 4, the glass manufacturing apparatus 1 is equipped with a radiation thermometer 50. The radiation thermometer 50 has a plurality of light-receiving elements (not shown). The plurality of light-receiving elements are arranged in a matrix. The path of the light received by each light-receiving element is different for each light-receiving element. Each light-receiving element transmits a signal corresponding to the light intensity to the image processing device 51. The image processing device 51 creates a temperature distribution diagram 100 (see Figure 5) corresponding to the light intensity of each light-receiving element 12.

[0031] In the radiation thermometer described in Patent Document 2, the optical axis of each light-receiving element is positioned perpendicular to the main surface of the glass ribbon. In this case, each light-receiving element receives the light emitted by the glass ribbon, but does not receive the light emitted by the surrounding material of the glass ribbon and reflected by the glass ribbon. Therefore, it is possible to measure the temperature of the glass ribbon, rather than the temperature of the surrounding material. Here, the surrounding material is, for example, a heater or a brick.

[0032] In the float method, unlike the fusion method described in Patent Document 2, the glass ribbon GR is kept horizontal. Therefore, in order to install the radiation thermometer 50 so that the optical axis of each light-receiving element of the radiation thermometer 50 is perpendicular to the main surface (e.g., the top surface) of the glass ribbon GR, it is necessary to open a window in the ceiling 61 of the heat treatment furnace 60.

[0033] The inventors of this application focused on the fact that glass ribbons GR formed by the float method have irregularities at their widthwise ends, as shown in Figure 4, in order to measure the temperature of the glass ribbons GR diagonally below the window 62a of the side wall 62 of a heat treatment furnace 60 that houses horizontal glass ribbons GR. These irregularities are formed by the top roll 33 pressing down on the glass ribbons GR, as shown in Figure 2. The number of recesses in the irregularities is approximately the same as the number of top rolls 33.

[0034] Furthermore, the central part of the glass ribbon GR in the width direction is smooth and has a uniform thickness. The glass plate product is cut from the central part of the glass ribbon GR in the width direction.

[0035] The glass ribbon GR formed by the float method has irregularities at its widthwise end, and a portion of these irregularities is perpendicular to the optical axis of the light-receiving element of the radiation thermometer 50. Therefore, the radiation thermometer 50 can measure the temperature of the glass ribbon GR, rather than the surrounding components, by measuring the temperature of the widthwise end of the glass ribbon GR diagonally below the window 62a in the side wall 62 of the heat treatment furnace 60 that houses the horizontal glass ribbon GR. Thus, it is unnecessary to open a window in the ceiling 61 of the heat treatment furnace 60.

[0036] As shown in Figure 4, the widthwise ends of the glass ribbon GR are thicker, have a larger heat capacity, and are less susceptible to temperature changes compared to the widthwise center of the glass ribbon GR (for example, the temperature does not drop easily during slow cooling). Therefore, a temperature difference may occur between the widthwise ends and the widthwise center of the glass ribbon GR inside the heat treatment furnace 60. The measurements from the radiation thermometer 50 are used for controlling the furnace temperature of the heat treatment furnace 60, etc.

[0037] The radiation thermometer 50 is preferably a two-color thermometer. The two-color thermometer measures the temperature of the glass ribbon GR based on the received intensity of light having a first wavelength and the received intensity of light having a second wavelength different from the first wavelength. The higher the temperature of the glass ribbon GR, the higher the intensity of light emitted by the glass ribbon GR. The intensity of light emitted by the glass ribbon GR changes not only with the temperature of the glass ribbon GR but also with the wavelength of light. The two-color thermometer measures the temperature of the glass ribbon GR based on the ratio (or difference) of the received intensities of the two wavelengths, etc.

[0038] Unlike monochromatic thermometers, two-color thermometers measure the temperature of the glass ribbon GR based on the received light intensity of two wavelengths, so the temperature of the glass ribbon GR can be measured without setting the emissivity of the glass ribbon GR. However, if the emissivity of the glass ribbon GR is set, the radiation thermometer 50 can function as a monochromatic thermometer.

[0039] A transparent member, such as a glass plate (not shown), may be fitted into the window 62a of the side wall 62. Both the two-color thermometer and the mono-color thermometer can measure the temperature of the glass ribbon GR through the transparent member.

[0040] The heat treatment furnace 60 is preferably an annealing furnace 45 (see Figure 1). Since the annealing furnace 45 slowly cools the glass ribbon GR, it has fewer heaters than the molding furnace 31. Also, the heater temperature of the annealing furnace 45 is lower than the temperature of the glass ribbon GR. Therefore, if the heat treatment furnace 60 is an annealing furnace 45, the effect of light emitted by the heaters can be reduced. However, the heat treatment furnace 60 does not have to be an annealing furnace 45; it may be a molding furnace 31 or a dross box 41. In the molding furnace 31 or dross box 41, the radiation thermometer 50 can be installed in a location with fewer heaters.

[0041] As shown in Figure 4, it is preferable that the glass manufacturing apparatus 1 includes an image processing device 51. The image processing device 51 creates a temperature distribution diagram 100 (see Figure 5) based on the measurements of the radiation thermometer 50. It is preferable that the glass manufacturing apparatus 1 further includes an image display device 52. The image display device 52 displays the temperature distribution diagram 100 created by the image processing device 51. This improves user convenience.

[0042] As shown in Figure 5, the temperature distribution diagram 100 has multiple linear regions 101 and 102 along the width direction (Y direction) of the glass ribbon GR, where the temperature is equal. In Figure 5, the grayscale represents temperature. The temperature increases as the color changes from black to white. The temperature distribution diagram 100 has a striped pattern.

[0043] The temperature distribution diagram 100 has a striped pattern because the glass ribbon GR has the same cross-sectional shape along its longitudinal direction. The glass ribbon GR, formed by the float method, has irregularities at its widthwise ends, and a portion perpendicular to the optical axis of the photodetector of the radiation thermometer 50 is located in the middle of these irregularities. This perpendicular portion extends along the longitudinal direction of the glass ribbon GR and has the same temperature. Therefore, the temperature distribution diagram 100 has a striped pattern.

[0044] One linear region 101 is a region where multiple photodetectors, arranged in the longitudinal direction (X-axis direction) of the glass ribbon GR, receive light. When the optical axes of these photodetectors are perpendicular to the surface of the glass ribbon GR, the temperature of one linear region 101 is the temperature of the glass ribbon GR. Another linear region 102 is also a region where multiple photodetectors, arranged in the longitudinal direction (X-axis direction) of the glass ribbon GR, receive light. When the optical axes of these photodetectors intersect the surface of the glass ribbon GR at an angle, the temperature of the other linear region 102 is the temperature of the surrounding material reflected on the glass ribbon GR. The multiple linear regions 101 and 102 have different temperatures.

[0045] The image processing device 51 compares the temperatures of multiple linear regions 101 and 102 to determine the temperature of the widthwise end of the glass ribbon GR. If the temperature of the glass ribbon GR is higher than the temperature of the surrounding material, the higher temperature among the multiple linear regions 101 and 102 is the temperature of the widthwise end of the glass ribbon GR. If the temperature of the glass ribbon GR is lower than the temperature of the surrounding material, the lower temperature among the multiple linear regions 101 and 102 is the temperature of the widthwise end of the glass ribbon GR.

[0046] The image processing device 51 preferably compares the temperatures of multiple linear regions 101 and 102 and determines the temperature of the widthwise end of the glass ribbon GR according to the type of heat treatment furnace 60. For example, if the heat treatment furnace 60 is an annealing furnace 45, the temperature of the glass ribbon GR tends to be higher than the temperature of the surrounding material. If the heat treatment furnace 60 is an annealing furnace 45, the higher of the temperatures of the multiple linear regions 101 and 102 is the temperature of the widthwise end of the glass ribbon G.

[0047] The image display device 52 may display the temperature of the glass ribbon GR in place of, or in addition to, the temperature distribution diagram 100. The temperature of the glass ribbon GR may be displayed overlaid on the temperature distribution diagram 100, or it may be displayed separately from the temperature distribution diagram 100.

[0048] The following additional information is disclosed regarding the above embodiments, etc. [Note 1] A glass manufacturing method comprising rotating a top roll while pressing down on the widthwise end of the upper surface of a horizontal strip-shaped glass ribbon with the top roll, A glass manufacturing method comprising measuring the temperature of the widthwise end of the glass ribbon diagonally below the window through a window in the side wall of a heat treatment furnace that houses the horizontal glass ribbon, using a radiation thermometer. [Note 2] The aforementioned radiation thermometer is a two-color thermometer, according to the glass manufacturing method described in Appendix 1. [Note 3] The glass manufacturing method according to Appendix 1 or 2, wherein the heat treatment furnace is an annealing furnace for slowly cooling the glass ribbon. [Note 4] The glass manufacturing method includes creating a temperature distribution map based on the measurement values ​​of the radiation thermometer. The temperature distribution diagram has multiple linear regions along the longitudinal direction of the glass ribbon where the temperature is equal, and in the width direction of the glass ribbon. The multiple linear regions are at different temperatures. The glass manufacturing method according to any one of the appendices 1 to 3, comprising comparing the temperatures of a plurality of linear regions and determining the temperature of the widthwise end of the glass ribbon. [Note 5] A top roll rotates while holding down the widthwise end of the upper surface of a horizontal, strip-shaped glass ribbon, A radiation thermometer measures the temperature of the widthwise end of the glass ribbon diagonally below the window, through a window in the side wall of a heat treatment furnace that houses the horizontal glass ribbon, A glass manufacturing apparatus equipped with the following features. [Note 6] The aforementioned radiation thermometer is a two-color thermometer, as described in Appendix 5 of the glass manufacturing apparatus. [Note 7] The glass manufacturing apparatus according to Appendix 5 or 6, wherein the heat treatment furnace is an annealing furnace for slowly cooling the glass ribbon. [Note 8] The system includes an image processing device that creates a temperature distribution map based on the measurements of the aforementioned radiation thermometer, The temperature distribution diagram has multiple linear regions along the longitudinal direction of the glass ribbon where the temperature is equal, and in the width direction of the glass ribbon. The multiple linear regions are at different temperatures. The glass manufacturing apparatus according to any one of the appendices 5 to 7, wherein the image processing apparatus compares the temperatures of a plurality of linear regions and determines the temperature of the widthwise end of the glass ribbon.

[0049] 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]

[0050] 1. Glass manufacturing equipment 33 Top Roll 50 radiation thermometer 60 Heat treatment furnaces 62 Side wall 62a Window GR Glass Ribbon

Claims

1. A glass manufacturing method comprising rotating a top roll while pressing down on the widthwise end of the upper surface of a horizontal strip-shaped glass ribbon with the top roll, A glass manufacturing method comprising measuring the temperature of the widthwise end of the glass ribbon diagonally below the window through a window in the side wall of a heat treatment furnace that houses the horizontal glass ribbon, using a radiation thermometer.

2. The glass manufacturing method according to claim 1, wherein the radiation thermometer is a two-color thermometer.

3. The glass manufacturing method according to claim 1, wherein the heat treatment furnace is an annealing furnace for slowly cooling the glass ribbon.

4. The glass manufacturing method includes creating a temperature distribution map based on the measurement values ​​of the radiation thermometer. The temperature distribution diagram has multiple linear regions along the longitudinal direction of the glass ribbon where the temperature is equal, and in the width direction of the glass ribbon. The multiple linear regions are at different temperatures. The glass manufacturing method according to claim 1, further comprising comparing the temperatures of a plurality of linear regions and determining the temperature of the widthwise end of the glass ribbon.

5. A top roll rotates while holding down the widthwise end of the upper surface of a horizontal, strip-shaped glass ribbon, A radiation thermometer measures the temperature of the widthwise end of the glass ribbon diagonally below the window, through a window in the side wall of a heat treatment furnace that houses the horizontal glass ribbon, A glass manufacturing apparatus equipped with the following features.

6. The glass manufacturing apparatus according to claim 5, wherein the radiation thermometer is a two-color thermometer.

7. The glass manufacturing apparatus according to claim 5, wherein the heat treatment furnace is an annealing furnace for slowly cooling the glass ribbon.

8. The system includes an image processing device that creates a temperature distribution map based on the measurements of the aforementioned radiation thermometer, The temperature distribution diagram has multiple linear regions along the longitudinal direction of the glass ribbon where the temperature is equal, and in the width direction of the glass ribbon. The multiple linear regions are at different temperatures. The glass manufacturing apparatus according to claim 5, wherein the image processing apparatus compares the temperatures of a plurality of linear regions and determines the temperature of the widthwise end of the glass ribbon.

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