Abnormal detection device, abnormal detection method, and method for producing a glass plate

Abstract

To provide an abnormality detection device which can detect abnormalities with high accuracy during various processing being performed to a workpiece, and to provide an abnormality detection method and a glass plate production method.SOLUTION: An abnormality detection device includes: an AE sensor 61 provided on a polishing surface plate 20 which processes a glass plate G placed on an upper part; a slurry passage 29 which is open on an upper surface 40a of a polishing plate 40 and is connected to a detection surface 63 of the AE sensor 61; a liquid supply device 12 which supplies slurry S to the slurry passage 29 to interpose the slurry S between the glass plate G and the detection surface 63 and send the slurry S from the upper surface 40a of the polishing plate 40; and an abnormality detection part 17 which determines if an abnormality occurs in the glass plate G based on a detection signal from the AE sensor 61 which detects an elastic wave from the glass plate G through the slurry S.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an abnormality detection device, an abnormality detection method, and a method for producing a glass plate.

Background Art

[0002] For example, during various processes on a glass plate used for a flat panel display (FPD) such as an LCD (Liquid Crystal Display) or an OLED (Organic Light-Emitting Diode), damage such as cracks may rarely occur in the glass plate. For this reason, as a polishing device for polishing a glass plate, one equipped with a detection device for early detection of cracks in the glass plate is known (see, for example, Patent Document 1).

[0003] This detection device includes a liquid supply unit that supplies liquid to the glass plate, an AE sensor disposed at a position in contact with the liquid, and a signal processing unit that processes an AE signal input from the AE sensor that detects an elastic wave from the glass plate. And in this detection device, the signal processing unit determines that the glass plate is cracked when the AE signal from the AE sensor exceeds a predetermined threshold value.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The detection device described in Patent Document 1 above has a slurry inflow hole that opens on the upper surface of the polishing table and is connected to the AE sensor, and the slurry supplied to the polishing pad flows into and fills the slurry inflow hole. As a result, the slurry is interposed between the detection surface of the AE sensor and the surface to be polished of the glass plate, and the elastic wave from the glass plate is detected in this state.

[0006] By the way, in the above detection device, if air is mixed into the slurry in the slurry inlet hole, the propagation of elastic waves may be blocked by the air mixed into the slurry, making it difficult to detect abnormalities such as minute cracks in the glass plate. In addition, solid particles contained in the slurry may accumulate on the detection surface of the AE sensor, possibly reducing the detection accuracy of cracks in the glass plate by the AE sensor.

[0007] Therefore, an object of the present invention is to provide an abnormality detection device, an abnormality detection method, and a method for producing a glass plate that can accurately detect abnormalities during various processes on a workpiece.

Means for Solving the Problems

[0008] The present invention is configured as follows. (1) An AE sensor provided on a processing table for processing a workpiece placed on the upper part, A flow path that opens on the upper surface of the processing table and is connected to the detection surface of the AE sensor, A liquid supply unit that supplies liquid to the flow path, interposes the liquid between the workpiece and the detection surface, and sends it out from the upper surface of the processing table, An abnormality detection unit that determines the presence or absence of an abnormality in the workpiece based on a detection signal from the AE sensor that detects elastic waves from the workpiece through the liquid, Comprising, Abnormality detection device. (2) An AE sensor is provided on a processing table for processing a workpiece placed on the upper part, Liquid is supplied to a flow path that opens on the upper surface of the processing table and is connected to the detection surface of the AE sensor through a supply flow path, interposing the liquid between the workpiece and the detection surface and sending it out from the upper surface of the processing table, The elastic waves from the workpiece are detected by the AE sensor through the liquid, Based on the detection signal from the AE sensor, the presence or absence of an abnormality in the workpiece is determined, Abnormality detection method. (3) Including the abnormality detection method of (2) above, Method for producing a glass plate.

Advantages of the Invention

[0009] According to the abnormality detection device, abnormality detection method, and production method of the present invention, abnormalities during various processes on a workpiece can be detected with high precision.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this example, the case where the abnormality detection device and abnormality detection method of the present invention are used to detect cracks when polishing a workpiece made of a glass plate will be exemplified and described. FIG. 1 is a schematic configuration diagram of a polishing apparatus to which the abnormality detection device of the present invention is applied. FIG. 2 is a schematic side view of a polishing apparatus to which the abnormality detection device of the present invention is applied. FIG. 3 is a partial cross-sectional view of the polishing apparatus.

[0012] As shown in FIGS. 1 and 2, the polishing apparatus (abnormality detection apparatus) 10 is an apparatus for polishing a glass plate (workpiece) G formed in a rectangular shape. The glass plate G polished by this polishing apparatus 10 is made of an alkali-free glass-based material used, for example, for flat panel displays (FPDs) such as liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs). This glass plate G is, for example, a glass plate with one side being 2000×2200 mm to 2200×2600 mm and a thickness of 0.7 mm, and is manufactured, for example, by the float process. The polishing apparatus 10 polishes the glass plate G to a flatness required for various applications.

[0013] The polishing apparatus 10 includes a polishing surface plate 20, a polishing plate 40, and a polishing head 50, and a processing table for processing the glass plate G is configured by the polishing surface plate 20 and the polishing plate 40. The polishing surface plate 20 is formed in a circular shape in plan view, and the polishing plate 40 is installed on its upper surface. The polishing head 50 is disposed above the polishing surface plate 20. The glass plate G is disposed above the polishing plate 40 installed on the polishing surface plate 20 and is pressed against the polishing plate 40 by the polishing head 50. A spindle 51 is provided at the center of the upper part of the polishing head 50, and a rotation / lift device 53 is connected to this spindle 51. The rotation / lift device 53 is connected to a control unit 11 that overall controls the entire polishing apparatus 10, and the control unit 11 controls the rotation speed and the lowering operation (pressing force) to a state suitable for polishing the glass plate G.

[0014] As shown in FIG. 3, a plurality of suction holes 31 and a plurality of slurry supply holes 33 that open on the upper surface are formed in the polishing surface plate 20. A suction pump (not shown) is connected to the suction holes 31, and a slurry supply machine (not shown) that supplies a slurry (liquid) S, which is a polishing liquid such as an aqueous cerium oxide solution, is connected to the slurry supply holes 33.

[0015] The polishing plate 40 installed on the upper surface of this polishing surface plate 20 has a resin buffer plate portion 41, an aluminum support plate portion 43, and a polishing pad 45, and these buffer plate portion 41, support plate portion 43, and polishing pad 45 are stacked in order. As the polishing pad 45, for example, a foamed polyurethane type or a suede type is used. A flow path 47 penetrating through the front and back is formed in this polishing plate 40, and these flow paths 47 communicate with the slurry supply hole 33 of the polishing surface plate 20.

[0016] The polishing plate 40 on the upper surface of the polishing surface plate 20 is adsorbed by the suction hole 31 and held on the upper surface of the polishing surface plate 20 when the suction pump operates. Then, when the operation of the suction pump is stopped and the suction at the suction hole 31 is released, it can be removed from the upper surface of the polishing surface plate 20.

[0017] Also, when the slurry S is supplied from the slurry supply machine to the slurry supply hole 33 of the polishing surface plate 20, the slurry S is sent into the flow path 47 communicating with the slurry supply hole 33 and supplied to the upper surface side of the polishing pad 45 of the polishing plate 40. As a result, the polishing pad 45 is immersed in the slurry S.

[0018] The polishing head 50 disposed above the polishing surface plate 20 holds the glass plate G via a sheet-like holding sheet 55 made of a backing material having a self-adsorbing action. The polishing head 50 is rotated and lifted by a spindle 51 driven by a rotation / lift device 53. Therefore, the glass plate G held by the polishing head 50 via the holding sheet 55 is pressed against the polishing plate 40 installed on the upper surface of the polishing surface plate 20 while being rotated at a rotation speed and pressing force suitable for polishing. As a result, the surface to be polished A, which is the surface on the polishing plate 40 side of the glass plate G, is polished to the required flatness by the polishing pad 45 of the polishing plate 40.

[0019] FIG. 4 is a cross-sectional view of the sensor portion provided on the polishing surface plate. FIG. 5 is a perspective view of the AE sensor.

[0020] As shown in Fig. 4, the polishing surface plate 20 has a sensor unit 21. The sensor unit 21 has a sensor housing portion 23 formed in a concave shape, and an AE (Acoustic Emission) sensor 61 is housed in the sensor housing portion 23. The AE sensor 61 has, for example, a piezoelectric element, and is a sensor that detects elastic waves emitted when a solid is deformed or broken by the piezoelectric element and outputs a detection signal thereof. As this AE sensor 61, one with a built-in preamplifier for amplifying the output detection signal is used.

[0021] The sensor unit 21 is provided at a lower position overlapping a glass plate G installed on the polishing surface plate 20. Thereby, the AE sensor 61 of the sensor unit 21 is disposed directly below the placement position of the glass plate G on the polishing surface plate 20.

[0022] As shown in Fig. 5, the periphery of the AE sensor 61 except for the detection surface 63 is covered by a resin cover 65. Thereby, the AE sensor 61 has waterproofness and insulation ensured by the cover 65. Also, a cable 67 is drawn out from the side portion of the AE sensor 61.

[0023] As shown in Fig. 4, the polishing surface plate 20 has a lid body 25 covering the sensor housing portion 23, and a through hole 25a is formed in the lid body 25. Also, a block 27 is fixed to the back surface side of the lid body 25 by screwing or the like. A communication hole 27a communicating with the through hole 25a formed in the lid body 25 is formed in the block 27. The through hole 25a and the communication hole 27a communicate with a hole portion 49 that penetrates the front and back of the polishing plate 40 and opens on the upper surface 40a of the polishing plate 40. And a slurry flow path (flow path) 29 is constituted by these mutually communicating through hole 25a, communication hole 27a, and hole portion 49.

[0024] The block 27 is formed with a mounting recess 27b having a diameter larger than that of the communication hole 27a, and the detection surface 63 side of the AE sensor 61 is fitted into this mounting recess 27b. Thereby, the AE sensor 61 is fixed to the lid body 25 via the block 27, and its detection surface 63 is exposed in the slurry flow path 29. And in the polishing surface plate 20, the angle formed between the detection surface 63 of the AE sensor 61 mounted on the lid body 25 and the upper surface 40a of the polishing plate 40 on which the glass plate G is placed is set to be 0° or more and 10° or less. Note that a packing 28 is provided on the inner periphery of the mounting recess 27b, and the packing 28 seals the space between the inner peripheral surface of the mounting recess 27b and the outer peripheral surface of the AE sensor 61.

[0025] A fitting hole 27c communicating with the communication hole 27a is formed in a side portion of the block 27 fixed to the lid body 25, and a slurry supply tube 35 is fitted and connected to this fitting hole 27c. Then, the slurry S is supplied from this slurry supply tube 35 to the slurry flow path 29, and the slurry flow path 29 is filled with the slurry S without any gaps. The slurry S supplied to the slurry flow path 29 is sent out from the upper part of the slurry flow path 29 toward the upper surface 40a side of the polishing plate 40.

[0026] An insertion hole 37 connected to the sensor housing portion 23 is formed in the polishing surface plate 20, and a cable 67 drawn out from the AE sensor 61 and the slurry supply tube 35 connected to the block 27 are inserted through this insertion hole 37. Then, the cable 67 and the slurry supply tube 35 inserted through the insertion hole 37 are drawn out from the outer peripheral surface of the polishing surface plate 20.

[0027] As shown in FIG. 1, the cable 67 from the AE sensor 61 drawn out from the polishing surface plate 20 is connected to the control unit 11 via the discriminator 15. Thereby, a detection signal indicating an elastic wave from the AE sensor 61 is transmitted to the abnormality detection unit 17 of the control unit 11. Note that the cable 67 drawn out from the polishing surface plate 20 and connected to the control unit 11 is a PLC (Power Line Communication) cable or the like.

[0028] The detection signal transmitted to the control unit 11 is amplified by a preamplifier built into the AE sensor 61, and only signals in a specific frequency band are extracted by the discriminator 15. The control unit 11 has an abnormality detection unit 17 and an alarm 19. The abnormality detection unit 17 detects an abnormality in the glass plate G during polishing based on the detection signal from the AE sensor 61. Further, when the abnormality detection unit 17 detects an abnormality in the glass plate G, the alarm 19 issues a warning.

[0029] Also, the slurry supply tube (supply flow path) 35 drawn out from the polishing platen 20 is connected to a liquid supply device (liquid supply unit) 12 and a gas supply device (gas supply unit) 13. Thereby, slurry S or water is sent into the slurry supply tube 35 from the liquid supply device 12, and air (gas) is sent into the slurry supply tube 35 from the gas supply device 13. The liquid supply device 12 is connected to a liquid supply amount adjustment unit 18 of the control unit 11, and the liquid supply amount adjustment unit 18 controls the supply amount, supply timing, and liquid feed pressure, etc. of the slurry S to the slurry supply tube 35 by the liquid supply device 12. Also, the gas supply device 13 is connected to a gas supply amount adjustment unit 14 of the control unit 11, and the gas supply amount adjustment unit 14 controls the supply amount, supply timing, etc. of the air to the slurry supply tube 35 by the gas supply device 13.

[0030] Next, the polishing process and abnormality detection of the glass plate G by the polishing apparatus 10 will be described. In the polishing process, the glass plate G is placed at the placement position on the polishing platen 20, and while pressing the glass plate G against the polishing plate 40 by the polishing head 50, it is rotated. Thereby, the polished surface A of the glass plate G is polished by the polishing pad 45 containing the slurry S supplied through the slurry supply hole 33.

[0031] In this polishing process, slurry S fed from the liquid supply device 12 to the slurry supply tube 35 is supplied to the slurry flow path 29 where the detection surface 63 of the AE sensor 61 provided in the sensor unit 21 is exposed. As a result, the slurry flow path 29 is filled with the slurry S without any gaps and sent to the upper surface 40a of the polishing plate 40.

[0032] In the polishing process, the slurry S is constantly supplied to the slurry flow path 29 from the liquid supply device 12. Thereby, the inflow of the slurry S from the opening side into the slurry flow path 29 that opens on the upper surface 40a of the polishing plate 40 is suppressed. Also, a flow is always generated in the slurry flow path 29, and it is possible to effectively suppress the deposition of solid particles in the slurry S on the detection surface 63 of the AE sensor 61. Further, even when the polishing apparatus is not operating, in order to suppress the deposition of solid particles in the slurry S on the detection surface 63 of the AE sensor 61, the slurry S or water may be supplied. In this case, it is preferable to supply water from the viewpoint of economy.

[0033] Therefore, the slurry S that has flowed into the slurry flow path 29 is interposed between the glass plate G and the detection surface 63 of the AE sensor 61 (see FIG. 4). Thereby, the elastic wave from the glass plate G is detected by the AE sensor 61 disposed directly below the placement position of the glass plate G on the polishing surface plate 20 through the slurry S.

[0034] When the output value of the AE sensor 61 exceeds a preset threshold value, the abnormality detection unit 17 determines that an abnormality has occurred in the glass plate G. Then, the control unit 11 of the polishing apparatus 10 stops the rotation / lifting device 53 at that time and activates the alarm 19 to issue a warning. Thereby, the influence on the glass plate G and the polishing pad 45 due to the continuation of the polishing of the glass plate G in the abnormal state is suppressed.

[0035] Also, by supplying air from the gas supply device 13 connected to the slurry supply tube 35 at predetermined time intervals, the slurry supply tube 35 is flushed. Thereby, it is possible to suppress the deposition of solid particles contained in the slurry S in the slurry supply tube 35, and further remove the solid particles deposited on the detection surface 63 of the AE sensor 61. During flushing, it is preferable to supply air from the gas supply device 13 and supply the slurry S or water from the liquid supply device 12 to form a mixed flow of gas and liquid. Thereby, it is possible to effectively suppress the deposition of solid particles in the slurry supply tube 35, and further effectively remove the solid particles deposited on the detection surface 63 of the AE sensor 61.

[0036] Also, for flushing, it is preferable to use compressed gas such as compressed air. By using compressed gas, it is possible to effectively suppress the deposition of solid particles in the slurry supply tube 35, and further effectively remove the solid particles deposited on the detection surface 63 of the AE sensor 61. The gas supplied to the slurry flow path 29 during flushing is discharged from the upper part of the slurry flow path 29 together with the liquid supplied from the liquid supply device 12.

[0037] As described above, according to the abnormality detection device and the abnormality detection method according to the present embodiment, the slurry S is directly supplied to the slurry flow path 29 that opens on the upper surface 40a of the polishing plate 40 constituting the processing table and is connected to the detection surface 63 of the AE sensor 61 by the liquid supply device 12, and is sent out to the upper surface 40a of the polishing plate 40. Therefore, compared with the case where the slurry S flows in from the opening on the upper surface 40a of the polishing plate 40, the mixing of air into the slurry S can be suppressed, and the deposition of solid particles in the slurry S on the detection surface 63 of the AE sensor 61 can be suppressed. Thereby, air is not mixed into the slurry S, and solid particles in the slurry S are not deposited on the detection surface 63 of the AE sensor 61, so that the propagation of elastic waves is not blocked, and the elastic waves from the glass plate G can be accurately detected. Therefore, abnormalities such as cracks and chips occurring in the glass plate G can be detected with high precision without false detection. Moreover, since elastic waves can be detected with high precision, minute cracks and chips can be detected, and not only cracks and chips but also abnormalities can be detected when the glass plate G is scratched.

[0038] Further, since the AE sensor 61 is disposed directly below the placement position of the glass plate G, the AE sensor 61 can accurately detect elastic waves from the glass plate G through the slurry S interposed therebetween. Also, compared with a structure for detecting elastic waves on the side of the glass plate G, even if the glass plate G is large, abnormalities occurring closer to the center in plan view can be detected well.

[0039] In addition, air is supplied from the gas supply device 13 to the slurry supply tube 35 connecting the slurry flow path 29 and the liquid supply device 12 at predetermined time intervals, and the slurry supply tube 35 is flushed. Thereby, it is possible to suppress the deposition of solid particles contained in the slurry S in the slurry supply tube 35. Also, even when solid particles in the slurry S are deposited on the detection surface 63 of the AE sensor 61, the solid particles deposited on the detection surface 63 of the AE sensor 61 can be removed to maintain good detection accuracy.

[0040] Further, since the angle formed by the detection surface 63 of the AE sensor 61 and the upper surface 40a of the polishing plate 40 constituting the processing table is 0° or more and 10° or less, the inclination of the detection surface 63 with respect to the glass plate G can be suppressed, and elastic waves can be more easily transmitted from the glass plate G to the detection surface 63, and the detection accuracy can be further improved.

[0041] According to the production method of the glass plate G including the above-described abnormality detection method, abnormalities such as cracks and chips occurring in the glass plate G can be detected with high precision without false detection. Thereby, damages such as cracks during various processes on the glass plate G can be quickly and accurately detected and dealt with, and productivity can be increased.

[0042] Note that the present invention can be applied to substrates of electronic devices other than LCDs, OLEDs, and FPDs, such as glass substrates for optical elements, glass disks, and solar cells. Further, the workpiece is not limited to a glass plate, and may be, for example, formed of metal, ceramic, or resin.

[0043] In the above embodiment, the case of detecting an abnormality in the polishing process of the workpiece made of the glass plate G is exemplified. However, the present invention is applicable not only to polishing but also to detecting abnormalities during various processes such as cutting, grinding, and coating.

[0044] As described above, the present invention is not limited to the above embodiments, and it is also contemplated by the present invention that those skilled in the art can make changes and applications based on combining each configuration of the embodiments with each other, the description in the specification, and well-known techniques, and these are included in the scope for which protection is sought.

[0045] As described above, the following matters are disclosed in this specification. (1) An AE sensor provided on a processing table for processing a workpiece placed on the upper part, A flow path that opens on the upper surface of the processing table and leads to the detection surface of the AE sensor, A liquid supply unit that supplies liquid to the flow path, interposes the liquid between the workpiece and the detection surface, and sends it out from the upper surface of the processing table, An abnormality detection unit that determines the presence or absence of an abnormality in the workpiece based on a detection signal from the AE sensor that detects an elastic wave from the workpiece through the liquid, An abnormality detection device comprising the above. According to the abnormality detection device having the configuration of (1) above, since the liquid is directly supplied by the liquid supply unit to the flow path connected to the detection surface of the AE sensor provided on the processing table and opening on the upper surface of the processing table, and is sent out from the upper surface of the processing table, it is possible to suppress the mixing of air into the liquid as compared with the case of allowing the liquid to flow into from the opening on the upper surface of the processing table. Further, when the liquid contains solid particles such as slurry, it is possible to suppress the deposition of the solid particles in the slurry on the detection surface of the AE sensor. Thereby, the propagation of elastic waves is not blocked due to the mixing of air into the liquid or the deposition of solid particles on the detection surface of the AE sensor, and the elastic waves from the workpiece can be accurately detected. Therefore, abnormalities such as cracks and chips generated in the workpiece can be detected with high precision without false detection. Moreover, since elastic waves can be detected with high precision, minute cracks and chips can be detected, and not only cracks and chips but also when the workpiece is damaged, the abnormality can be detected.

[0046] (2) The abnormality detection device according to (1), wherein the AE sensor is disposed directly below the placement position of the workpiece. According to the abnormality detection device having the configuration of (2) above, the elastic waves from the workpiece can be accurately detected through the liquid interposed between the workpiece and the AE sensor disposed directly below the placement position of the workpiece on the processing table. Further, compared with the structure for detecting elastic waves on the side of the workpiece, even if the workpiece is large, abnormalities generated closer to the center in plan view can also be detected well.

[0047] (3) The abnormality detection device according to (1) or (2), wherein the workpiece is a glass plate. According to the abnormality detection device having the configuration of (3) above, abnormalities during various processes on the glass plate can be detected with high precision.

[0048] (4) The liquid is slurry, and has a gas supply unit connected to a supply flow path connecting the liquid supply unit and the flow path. The gas supply unit supplies gas to the supply flow path every predetermined time, and is the abnormality detection device according to any one of (1) to (3). According to the abnormality detection device having the configuration of (4) above, by supplying gas from the gas supply unit every predetermined time, it is possible to perform flushing of the supply flow path. Thereby, it is possible to suppress the deposition of solid particles contained in the slurry in the supply flow path. Further, even when solid particles in the slurry are deposited on the detection surface of the AE sensor, it is possible to remove the solid particles deposited on the detection surface of the AE sensor and maintain good detection accuracy.

[0049] (5) The angle formed between the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less, and is the abnormality detection device according to any one of (1) to (4). According to the abnormality detection device having the configuration of (5) above, since the angle formed between the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less, the inclination of the detection surface with respect to the workpiece can be suppressed, and elastic waves can be more easily transmitted from the workpiece to the detection surface, and the detection accuracy can be further improved.

[0050] (6) An AE sensor is provided on a processing table for processing a workpiece placed on the upper part, Liquid is supplied through the supply flow path to a flow path that opens on the upper surface of the processing table and is connected to the detection surface of the AE sensor, and the liquid is interposed between the workpiece and the detection surface and sent out from the upper surface of the processing table, An elastic wave from the workpiece is detected by the AE sensor through the liquid, An abnormality detection method for determining the presence or absence of an abnormality in the workpiece based on a detection signal from the AE sensor. According to the method for detecting an abnormality in the configuration of (6) above, since the liquid is directly supplied by the liquid supply unit to the flow path that opens on the upper surface of the processing table and leads to the detection surface of the AE sensor provided on the processing table, and is sent out from the upper surface of the processing table, it is possible to suppress the mixing of air into the liquid as compared with the case of allowing the liquid to flow into the opening on the upper surface of the processing table. Further, when the liquid contains solid particles such as slurry, it is possible to suppress the deposition of the solid particles in the slurry on the detection surface of the AE sensor. As a result, the propagation of elastic waves is not blocked due to the mixing of air into the liquid or the deposition of solid particles on the detection surface of the AE sensor, and the elastic waves from the workpiece can be accurately detected. Therefore, abnormalities such as cracks and chips generated in the workpiece can be detected with high accuracy without false detection. Moreover, since elastic waves can be detected with high accuracy, minute cracks and chips can be detected, and not only cracks and chips but also abnormalities can be detected when the workpiece is damaged.

[0051] (7) The abnormality detection method according to (6), wherein the AE sensor is disposed directly below the placement position of the workpiece on the processing table. According to the abnormality detection method having the configuration of (7) above, the elastic waves from the workpiece can be accurately detected through the liquid interposed between the workpiece and the AE sensor disposed directly below the placement position of the workpiece on the processing table. Further, compared with a structure for detecting elastic waves on the side of the workpiece, even if the workpiece is large, abnormalities occurring closer to the center in plan view can also be detected well.

[0052] (8) The abnormality detection method according to (6) or (7), wherein the workpiece is a glass plate. According to the abnormality detection method having the configuration of (8) above, abnormalities during various processes on the glass plate can be detected with high accuracy.

[0053] (9) Using slurry as the liquid, The abnormality detection method according to any one of (6) to (8), wherein gas is supplied to the supply flow path at predetermined time intervals. According to the method for detecting an abnormality in the configuration of (9) above, by supplying gas from the gas supply unit at predetermined time intervals, the supply passage can be flushed. Thereby, it is possible to suppress the deposition of solid particles contained in the slurry in the supply passage. Further, even when solid particles in the slurry are deposited on the detection surface of the AE sensor, the solid particles deposited on the detection surface of the AE sensor can be removed to maintain good detection accuracy.

[0054] (10) The method for detecting an abnormality according to any one of (6) to (9), wherein the angle formed by the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less. According to the method for detecting an abnormality in the configuration of (10) above, since the angle formed by the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less, the inclination of the detection surface with respect to the workpiece can be suppressed, and elastic waves can be more easily transmitted from the workpiece to the detection surface, so that the detection accuracy can be further improved.

[0055] (11) Including the method for detecting an abnormality according to any one of (6) to (10), A method for producing a glass plate. According to the method for producing a glass plate in the configuration of (11) above, abnormalities such as cracks and chips generated in the glass plate can be detected with high accuracy without false detection. Thereby, damages such as cracks during various processes on the glass plate can be quickly and accurately detected and dealt with, and productivity can be improved.

Explanation of symbols

[0056] 10 Polishing device (abnormality detection device) 12 Liquid supply device (liquid supply unit) 13 Gas supply device (gas supply unit) 17 Abnormality detection unit 20 Polishing surface plate (processing table) 29 Slurry passage (passage) 35 Slurry supply tube (supply passage) 40 Polishing plate (processing table) 40a Upper surface 61 AE sensor 63 Detection surface G Glass plate (workpiece) S Slurry (liquid)

Claims

1. An AE sensor provided on a processing table for processing a workpiece placed thereon, a flow path connecting from a hole opening on the upper surface of the processing table to the detection surface of the AE sensor, a liquid supply unit that supplies liquid to the flow path, interposes the liquid between the workpiece and the detection surface, and discharges the liquid from the upper surface of the processing table, an abnormality detection unit that determines the presence or absence of an abnormality in the workpiece based on a detection signal from the AE sensor that detects elastic waves from the workpiece through the liquid, a supply flow path connecting the liquid supply unit and the flow path, comprising: the supply flow path is connected to the liquid supply unit between the hole portion and the detection surface in the flow path, an abnormality detection device.

2. The AE sensor is disposed directly below the placement position of the workpiece, The abnormality detection device according to claim 1.

3. The workpiece is a glass plate, The abnormality detection device according to claim 1 or claim 2.

4. The liquid is a slurry, having a gas supply unit connected to the supply flow path, the gas supply unit supplies gas to the supply flow path at predetermined time intervals, The abnormality detection device according to any one of claims 1 to 3.

5. The angle formed between the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less, The abnormality detection device according to any one of claims 1 to 4.

6. An AE sensor is provided on a processing table for processing a workpiece placed thereon, liquid is supplied through a supply flow path to a flow path connecting from a hole opening on the upper surface of the processing table to the detection surface of the AE sensor, and the liquid is interposed between the workpiece and the detection surface and discharged from the upper surface of the processing table between the hole portion and the detection surface in the flow path, elastic waves from the workpiece are detected by the AE sensor through the liquid, the presence or absence of an abnormality in the workpiece is determined based on a detection signal from the AE sensor, an abnormality detection method.

7. The AE sensor is disposed directly below the placement position of the workpiece on the processing table, The abnormality detection method according to claim 6.

8. The workpiece is a glass plate, The abnormality detection method according to claim 6 or claim 7.

9. using slurry as the liquid, supplying gas to the supply flow path at predetermined time intervals, The abnormality detection method according to any one of claims 6 to 8.

10. The angle formed between the detection surface of the AE sensor and the upper surface of the processing table is 0° or more and 10° or less. The abnormality detection method according to any one of claims 6 to 9.

11. An abnormality detection method according to any one of claims 6 to 10, A method for producing a glass plate.

12. In the flow path, the liquid is filled without gaps and sent out to the upper surface of the processing table, The abnormality detection device according to any one of claims 1 to 5.

13. In the flow path, the liquid is filled without gaps and sent out to the upper surface of the processing table, The abnormality detection method according to any one of claims 6 to 10.

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