JPWO2010067732A1 - Polishing apparatus, polishing method, and glass plate manufacturing method - Google Patents

Abstract

According to the present invention, the polishing tool and the object to be polished are relatively pressed and moved, and the object to be polished is polished by the polishing tool while supplying a polishing liquid between the polishing tool and the object to be polished. An AE sensor attached to the polishing tool or a plate that supports the object to be polished, and an output from the AE sensor when an elastic wave from the object to be polished is detected by the AE sensor. The present invention relates to a polishing apparatus comprising: an abnormality detection unit that detects an abnormality during polishing based on a signal; and a warning unit that issues a warning when an abnormality of the workpiece is detected by the abnormality detection unit. .

Description

  The present invention relates to a polishing apparatus, a polishing method, and a method for manufacturing a glass plate that detect abnormalities such as cracks generated in the glass plate during processing when the glass plate or the like is processed.

  In the glass plate manufacturing process, various processes such as cutting, chamfering, drilling, polishing, thermoforming, and air-cooling strengthening are performed on the glass plate. For example, a glass plate used for a flat panel display (FPD) such as an LCD or OLED has a factor that affects the image due to minute irregularities and undulations on the surface thereof, and therefore a part or the whole of the surface of the glass plate. May be polished by a polishing apparatus.

  In order to perform such polishing, a polishing apparatus including a moving polishing head that holds and conveys a glass plate and a plurality of polishing surface plates disposed below the polishing head is known. According to this polishing apparatus, the glass plate is conveyed by the moving polishing head, and the glass plate is sequentially polished by the plurality of polishing surface plates.

  By the way, during polishing of a glass plate by a polishing apparatus, the glass plate rarely breaks. In such a case, if the polishing process is continued while the glass plate is broken, the polishing pad is damaged by the broken glass piece. In addition, there is a problem that a subsequent glass plate is adversely affected during continuous polishing in which a plurality of glass plates are sequentially polished in the production process. For this reason, it is desired to detect the breakage of the glass plate at an early stage and quickly stop the polishing apparatus.

  Patent Document 1 discloses a crack detection device that detects a crack in a glass plate during polishing. This glass breakage detection device collects processing sound generated during polishing by the microphone 30 and extracts sound waves of a predetermined frequency (3 kHz or more) from the collected processing sound by a filter. The crack of the glass plate is determined by comparing the current sound wave level and the steady sound wave level in the past predetermined time from the present time.

Japanese Unexamined Patent Publication No. 2006-35343

  However, since the crack detection apparatus of patent document 1 detects the crack of the glass plate under grinding | polishing by a sound, it can detect only with the sound in the state where the glass plate was shattered, and generation | occurrence | production of a crack. Sound at the initial stage (small cracks such as cracks and chips) cannot be detected. Also, it is susceptible to noise from surrounding audio frequency components.

  When the glass plate is broken into small pieces, the polishing pad is damaged as described above, and it takes several hours for the cleaning operation to remove it. For this reason, the time required for the return operation and the polishing operation in the production process are interrupted, so that there is a disadvantage that the operation rate is lowered.

  Note that it is almost impossible to detect the extremely small sound generated at the initial stage of crack generation because it is drowned out by noise around the polishing apparatus. In addition, even if the monitor constantly monitors the glass plate being polished, it is not possible for the monitor to listen to the sound directly with the ear and discriminate it from the surrounding sound wave level to detect cracks in the glass plate being polished. It was possible.

  The present invention has been made in view of such circumstances, and is caused by damage to a polishing tool, cleaning work, and the like by detecting an initial stage of occurrence of abnormality such as cracking of an object to be polished during polishing. It is an object of the present invention to provide a polishing apparatus, a polishing method, and a glass plate manufacturing method capable of reducing the interruption time and suppressing the occurrence of unnecessary loss time.

  That is, the present invention relates to a polishing apparatus that relatively presses and moves a polishing tool and an object to be polished, and polishes the object to be polished by the polishing tool while supplying a polishing liquid between the polishing tool and the object to be polished. An AE sensor attached to a polishing tool or a plate that supports an object to be polished and an output signal from the AE sensor when an elastic wave from the object to be polished is detected by the AE sensor. There is provided an abrading apparatus comprising: an anomaly detecting section for detecting an anomaly of the apparatus; and a warning means for issuing a warning when an abnormality of the object to be polished is detected by the anomaly detecting section.

  Further, the present invention provides a polishing method in which a polishing tool and an object to be polished are relatively pressed and moved, and the object to be polished is polished by the polishing tool while supplying a polishing liquid between the polishing tool and the object to be polished. An abnormality detection unit based on an output signal from the AE sensor when an AE sensor is attached to a plate that supports the polishing tool or the object to be polished, and an elastic wave from the object to be polished is detected by the AE sensor. Provides a polishing method in which an abnormality during polishing is detected, and a warning means issues a warning when the abnormality detection unit detects an abnormality of the object to be polished.

  When the polishing tool is a polishing pad and the object to be polished is a glass plate, for example, it is suitable for polishing a mother glass substrate for LCD or OLED.

  Moreover, when the said polishing tool is a truing grindstone and the said to-be-polished object is a polishing pad, it is suitable for the truing operation | work of a polishing pad.

  Moreover, this invention provides the manufacturing method of the glass plate which processes a glass plate using said grinding | polishing method.

  In the present invention, the elastic wave generated from the glass plate being polished or the polishing pad being truing passes through the polishing liquid and is always detected by an AE (acoustic emission) sensor, and the information is constantly output to the abnormality detection unit. ing. In the abnormality detection unit, a threshold value at which micro cracks such as cracks and chips have occurred and a proper truing efficiency threshold value of the polishing pad are set in advance. When the output value from the AE sensor exceeds the threshold value during polishing, that is, when the abnormality detection unit detects that a small crack or chip such as a crack has occurred in the glass plate, or the output value from the AE sensor during truing. When the threshold value decreases, the warning means issues a warning.

  During the glass polishing, the control unit stops the polishing apparatus at the same time as issuing a warning. This makes it possible to detect the occurrence of abnormality such as a reduction in truing efficiency and the initial stage of cracking of the glass plate. Therefore, it is possible to detect a crack in the glass plate and stop the polishing apparatus before the glass plate is shattered. Therefore, according to the present invention, it is possible to minimize interruption time due to damage to the polishing pad, cleaning work, or the like. Alternatively, the processing after the abnormality detection can be substantially automated using a mechanical device and computer control without relying on human hands.

  In the polishing process of the glass plate, the polishing pad and the glass plate are relatively complicated to rotate and slide, and are continuously operated while always generating a large mechanical vibration. In addition, generation of electromagnetic noise from the motor and power supply system also exists in the vicinity of the process. Therefore, the AE sensor in the present invention can detect low-level elastic waves and unavoidable noise components generated during normal polishing of the glass plate. Under such circumstances, detecting an elastic wave in a steady state as a case of a crack in a glass plate and judging that an abnormality has occurred may disturb the polishing process.

  Therefore, in the present invention, the threshold is set based on experimental values or experience values. Furthermore, it has an automatic threshold value adjustment function that uses a value obtained by adding an added value to the maximum value from the past maximum value record in the specified range, and it is possible to select which threshold value to use. A case where a signal component exceeding the selected threshold is detected is determined as “abnormal”. In the example of FIG. 3, 1.000 V is set as the threshold value. When the polishing apparatus is stably and steadily operated, the noise resistance design of the detection circuit, the signal amplification factor, and the like are set so that the noise level is 0.1 V or less.

  In the present invention, when a minute crack such as a crack or a chip occurs in the glass plate being polished, it is meaningful to detect it instantaneously and stop the polishing apparatus once. In the conventional method, the time spent for cleaning the polishing head and the polishing pad cannot be ignored. However, according to the present invention, since the glass plate is not crushed, the time spent for the cleaning work is short, and it is sufficient to be within several tens of minutes. Therefore, the interruption time of the polishing apparatus in the production process can be greatly shortened. In the present invention, for example, as shown in FIG. 8, a micro crack or the like is a short part of a large mother glass substrate that is cracked within several centimeters to several tens of centimeters, or penetrates the front and back of a glass plate. It refers to a state where a small number of cracks have occurred.

  Furthermore, in the present invention, an AE sensor is attached to a plate that holds the polishing pad on a polishing surface plate. Thereby, the AE sensor can accurately detect the elastic wave generated during polishing. Further, since the polishing apparatus uses water or slurry as the polishing liquid, the metal part other than the insulated detection surface of the AE sensor is physically contacted with the plate held on the polishing surface plate or via water or slurry. If they are brought into electrical contact, electrical noise may enter the AE sensor, and an abnormal signal at a minute level may not be discriminated. Therefore, it is preferable to attach a resin (insulating) cover for waterproofing and insulation to the AE sensor.

  Further, it is preferable that the detection surface of the AE sensor is not attached to the plate as it is, but is attached to the plate through a metal cover that is in contact with the detection surface of the AE sensor and covers substantially the whole from the viewpoint of waterproofing. At this time, it is preferable to provide a biasing means such as a spring that presses the detection surface of the AE sensor against the metal cover from the viewpoint of increasing the detection accuracy of occurrence of a minute level abnormality.

  In the present invention, it is preferable that the polishing apparatus for the glass plate is stopped after the abnormality detection unit detects a crack in the glass plate. The flowchart is shown in FIG. That is, the glass plate crack detection device is set up (S1), the processing of the glass plate is started (S2), and when the fine crack of the glass plate is detected, the polishing device is stopped (S3) and the polishing part is checked Perform (S4) and restore the polishing apparatus (S5).

  For example, when the abnormality detection unit detects the initial stage of occurrence of cracks in the glass plate, a control unit that performs overall control of the entire polishing apparatus may be configured to stop the polishing apparatus. This eliminates the need for human work such as monitoring of the polishing apparatus by the monitor. Moreover, since the influence on another glass plate can be prevented in the case of continuous grinding | polishing, the quality of a glass plate, an operation rate, and a yield improve, respectively. Furthermore, when the polishing apparatus is stopped, the glass plate is preferably lifted (retracted) from the polishing pad together with the polishing head. Thereby, it becomes possible to easily take out the glass plate at the initial stage of occurrence of cracking from the polishing head.

  In the present invention, it is preferable that the AE sensor detects an elastic wave from a glass plate from a polishing liquid that has penetrated the polishing pad via the plate. As the polishing liquid, it is preferable to use a slurry containing cerium oxide or silica when polishing a glass plate and to use water when truing a polishing pad.

  The polishing pad is usually made of urethane, and urethane itself is difficult to transmit elastic waves. However, since the polishing liquid penetrates into the urethane polishing pad, the elastic wave from the glass plate is passed through the plate from this polishing liquid. Is reliably detected by the AE sensor. As the means for supplying the polishing liquid, a means for forming a large number of polishing liquid supply holes in the polishing surface plate and the plate and supplying the polishing liquid from these polishing liquid supply holes to the polishing pad is preferable. Thereby, water or slurry can be uniformly supplied to the whole polishing pad.

  In the present invention, the AE sensor is preferably formed on the plate and attached to the lower surface of the protruding piece of the plate that protrudes laterally from the polishing surface plate.

If the AE sensor is attached to the lower surface of the protruding piece of the plate that protrudes laterally from the polishing surface plate, the rotating polishing head can be prevented from colliding with the AE sensor. In addition, as an attachment position of the AE sensor, a through hole may be formed in the central portion of the polishing surface plate, and the detection surface of the AE sensor may be attached to the plate through the through hole. If the AE sensor is attached to the central portion of the polishing surface plate in this manner, the distance between the glass plate cracking position and the AE sensor is often shortened, so that the detection sensitivity of the elastic wave is improved.
What is necessary is just to determine suitably the number of AE sensors to attach according to the magnitude | size of a glass plate. For example, it is preferable to attach two or more AE sensors to a glass plate having a side of 3000 mm × 3000 mm or more.
In the case where a plurality of AE sensors are attached, the attachment positions of the AE sensors are preferably arranged substantially evenly with respect to the glass plate in order to improve detection sensitivity. For example, when two AE sensors are attached, it is preferable to attach them so that the AE sensors are symmetric with respect to the glass plate.

  In the present invention, it is preferable that the frequency band output from the AE sensor to the abnormality detection unit is set in a range of 100 to 200 kHz by a filter.

  Various devices such as a glass plate cutting device, a chamfering device, a transport device, and a secondary polishing device are installed around the glass plate polishing device. It is necessary to eliminate elastic waves with frequencies below 100 kHz due to mechanical vibrations from these devices. In addition, it is necessary to eliminate elastic waves having a frequency exceeding 200 kHz due to electrical noise.

  Therefore, in the present invention, since the lower limit value of the frequency band output from the AE sensor to the abnormality detection unit is 100 kHz, it is possible to prevent erroneous detection due to the elastic wave of the mechanical vibration, and the upper limit value is 200 kHz. Therefore, it is possible to prevent erroneous detection due to the elastic wave of the electrical noise. Thus, by selecting a target frequency band and setting a predetermined threshold, it was possible to achieve separation from surrounding noise components.

  Note that the higher the upper limit value, the less the output of the AE sensor is attenuated. Moreover, although a filter may be incorporated in the AE sensor itself, an output from the AE sensor may be output to the abnormality detection unit via the filter. A discriminator is preferably used as the filter.

  As described above, according to the present invention, the initial stage of occurrence of abnormality such as cracking of the workpiece being polished is detected by the AE sensor, so that the interruption time caused by damage to the polishing tool, the workpiece, cleaning, etc. Can be minimized.

  As a result, continuous operation in the polishing process can be improved, and the efficiency of the production plant can be improved. Further, since occurrence of a minute level of abnormality can be detected at an early stage, damage to the polishing apparatus and the polishing pad can be prevented, and maintenance of the apparatus can be facilitated.

FIG. 1 is a perspective view of a polishing apparatus of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the polishing apparatus of FIG. FIG. 3 is a waveform diagram showing an output waveform from the AE sensor and a threshold value. FIG. 4 is an enlarged perspective view of the AE sensor. 5A is a perspective view of an AE sensor covered with a resin cover, FIG. 5B is a perspective view of the metal cover as viewed from below, and FIG. 5C is a view of the metal cover. It is the perspective view seen from the upper part. FIG. 6 is a partial cross-sectional view of the polishing apparatus showing another attachment position of the AE sensor. FIG. 7 is a flowchart of the glass plate manufacturing method of the present invention. FIG. 8 is a top view showing a micro-level crack in the glass plate.

  Hereinafter, preferred embodiments of a polishing apparatus, a polishing method, and a glass plate manufacturing method according to the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a polishing apparatus 10 according to an embodiment. FIG. 2 is an enlarged cross-sectional view showing the main structure of the polishing apparatus 10.

  This polishing apparatus 10 is a glass plate G manufactured in a rectangular shape (for example, polishing manufactured by a float method made of a non-alkali glass material for one side of 2000 × 2200 mm to 2200 × 2600 mm, a thickness of 0.7 mm, and FPD). It is a polishing apparatus that polishes the front glass plate (for example, AN100)} to the flatness required for the glass plate for liquid crystal display.

  The structure includes a polishing head 16 that holds a glass plate G on its lower surface via a sheet-like holding member 14, and a polishing surface plate 22 that holds a polishing pad 20 on its upper surface via an aluminum plate 18. It is configured. The glass plate G is held by a holding member 14 made of a self-adsorbing backing material or the like, and the polished surface A is pressed against the polishing pad 20 by the polishing head 16 so that the polished surface A is required to be flat. Polished every time.

  During polishing, as shown in FIG. 2, a slurry, such as a cerium oxide aqueous solution, is passed through a number of polishing liquid supply holes 24, 24... Penetratingly formed in the polishing surface plate 22 and the plate 18. 20 is supplied from the lower surface side. Thus, the polishing pad 20 is immersed in the slurry, and the glass plate G is polished in this state. The polishing liquid supply holes 24, 24... Are formed densely and uniformly in the polishing surface plate 22 and the plate 18.

  Therefore, the slurry is uniformly supplied to the polishing pad 20. As the polishing pad 20, for example, a foamed polyurethane type or a suede type is used, and is adhered to the plate 18.

  Further, the polishing pad 20 may be one in relation to the glass plate G that is the object to be polished, but since the size of the polishing pad 20 is large corresponding to the size of the glass plate G, a plurality of divided polishings are performed. A single polishing pad 20 may be formed by combining the pads.

  Further, a large number of suction holes 26, 26... Are formed through the polishing surface plate 22, and these suction holes 26, 26... Are connected to a suction pump (not shown) via a valve. Therefore, by opening the valve, the suction force of the suction pump is transmitted to the suction holes 26, 26..., So that the plate 18 is adsorbed and held on the upper surface of the polishing surface plate 22. In addition, since the suction force of the suction pump is released by closing the valve, the polishing pad 20 can be removed from the polishing surface plate 22 together with the plate 18 when the state of the polishing pad 20 is checked or replaced.

  As shown in FIG. 1, a spindle 28 is fixed to the upper center of the polishing head 16, and a rotation / lifting device 30 is connected to the spindle 28. The rotation / lifting device 30 is controlled by a control unit 32 that performs overall control of the entire polishing device 10, and the rotation speed and lowering operation (pressing force) suitable for polishing the glass plate G are controlled.

  On the other hand, the polishing apparatus 10 includes an AE (acoustic emission) sensor 34, an abnormality detection unit 36, and an alarm (warning unit) 38. As the AE sensor 34, one having a resonance frequency of 140 to 150 kHz is used in order to satisfactorily detect a crack in the initial stage of the glass plate G. The resonance frequency is preferably set near the center of the frequency band to be detected. The AE sensor 34 is attached to the plate 18. Further, the abnormality detection unit 36 is a glass plate that is being polished based on an output signal from the AE sensor 34 when an elastic wave from the glass plate G that is being polished passes through the slurry and is detected by the AE sensor 34. The crack of the initial stage of G is detected. Further, the alarm 38 is controlled by the control unit 32 so as to issue a warning when the abnormality detection unit 36 detects an initial crack of the glass sheet G.

  By the way, a signal indicating an elastic wave detected by the AE sensor 34 is amplified by a predetermined amount by the preamplifier 40, and only a signal in a predetermined frequency band is extracted by a discriminator 42, which will be described later. It is transmitted to the abnormality detection unit 36 using a high-speed communication method such as Line Communication). The abnormality detection unit 36 is configured by a recording medium such as a CD-ROM in which an algorithm for determining an initial crack of the glass plate G that occurs during polishing is incorporated. Further, the cable 44 that transmits a signal to the PLC is routed around a place that is likely to be a noise source such as an inverter motor or a power line.

  On the other hand, the elastic wave generated during polishing of the glass plate G by the polishing apparatus 10 passes through the slurry and is always detected by the AE sensor 34, and the information is constantly output to the abnormality detection unit 36. In the anomaly detection unit 36, a threshold value that allows the occurrence of micro-cracks or chips such as cracks in the glass plate G is set in advance.

  FIG. 3 shows an output signal from the AE sensor 34 indicating the threshold value (1 V). When the output value from the AE sensor 34 exceeds the threshold value (1V), that is, the abnormality detection unit 36 detects that an abnormality such as a microcrack or a crack such as a crack has occurred in the glass plate G. The alarm 38 then issues a warning. At the same time as a warning is issued from the alarm 38, the polishing unit 10 is automatically stopped immediately by the control unit 32.

  As a result, according to the polishing apparatus 10 of the embodiment, the initial stage of the occurrence of cracking of the glass plate G can be detected by the AE sensor 34, and the polishing apparatus 10 is automatically stopped immediately at that time. The crack of the glass plate G can be detected before the glass plate G is shattered. Therefore, according to this polishing apparatus 10, the interruption time resulting from the check of the polishing pad 20, the cleaning operation, the replacement operation, and the like can be minimized.

  Note that the AE sensor 34 also detects low-level elastic waves generated during normal polishing of the glass plate G, but it is determined that even such elastic waves are detected as cracks. There is a risk of disturbing the polishing process. Therefore, in the polishing apparatus 10 according to the embodiment, the threshold value (1 V) based on an experimental value or an empirical value or a value calculated by an automatic threshold adjustment function is set as the threshold value.

  Further, even when a minute crack such as a crack or chipping occurs in the glass plate G being polished, it is necessary to stop the polishing apparatus 10 once and clean the holding member 14, the polishing head 16, and the polishing pad 20. However, in general, the glass plate G is rarely crushed suddenly, and a minute level of cracking or chipping is likely to occur at first. Therefore, the time required for the cleaning operation and the returning operation is sufficient for several tens of minutes. . Therefore, the interruption time can be greatly shortened.

  Further, in the polishing apparatus 10 of the embodiment, the AE sensor 34 is attached to the plate 18 that holds the polishing pad 20 on the polishing surface plate 22. Thereby, the AE sensor 34 can accurately detect the elastic wave generated during polishing.

  In addition, since the polishing apparatus 10 uses slurry when polishing the glass plate G, there is a possibility that electrical noise is generated due to conduction between the plate 18 and the AE sensor 34 excluding the AE sensor detection surface 34A. In order to prevent the electrical noise, it is preferable to attach a resin cover 46 for waterproofing and insulation shown in FIG. 5A to the AE sensor 34 shown in FIG. The cover 46 covers a portion excluding the detection surface 34A of the AE sensor 34. Furthermore, the detection surface 34A of the AE sensor 34 is not directly attached to the plate 18, but is detected by the AE sensor 34 from the viewpoint of waterproofing and prevention of electrical continuity due to slurry as shown in FIGS. 5 (B) and 5 (C). It is preferable to attach to the plate 18 through a metal cover 48 that is in contact with the surface 34A and covers substantially the entire surface. At this time, it is preferable to provide an urging means (not shown) such as a spring for pressing the detection surface 34A of the AE sensor 34 against the cover 48 from the viewpoint of increasing detection accuracy.

  5B and 5C will be described. FIG. 5B is a perspective view of the cover 48 viewed from below, and FIG. 5C is a perspective view of the cover 48 viewed from above. is there. The cover 48 is a box having an open bottom, and the detection surface 34A of the AE sensor 34 is pressed and fixed to the center of the lower surface of the top plate 48A via the urging means.

  Further, nuts 48C and 48C are formed on both sides of the top plate 48A with the attachment portion 48B of the AE sensor 34 interposed therebetween. Then, through holes (not shown) are formed in the plate 18 so as to correspond to the nut parts 48C, 48C, and bolts (not shown) are passed through these through holes and fastened to the nut parts 48C, 48C. A cover 48 is fixed to the plate 18.

  The system of the polishing apparatus is configured such that when a warning is issued from the alarm 38 in FIG. 1, the control unit 32 that performs overall control of the entire polishing apparatus 10 stops the polishing apparatus 10.

  This eliminates the need for monitoring the polishing apparatus 10 by a monitor. Moreover, since the influence on the subsequent glass plate G after an abnormality has occurred during continuous polishing can be prevented, the quality, operating rate, and yield of the glass plate G are improved. Further, it is preferable that the controller 32 controls the rotation / lifting device 30 so that the glass plate G is lifted (retracted) from the polishing pad 20 together with the polishing head 16 when the polishing device 10 is stopped. This makes it possible to easily take out the glass plate G at the initial stage of crack generation from the polishing head 16.

  The AE sensor 34 detects the elastic wave from the glass plate G from the slurry that has penetrated the polishing pad 20 through the plate 18. FIG. 6 shows the principle of detecting a crack in the glass plate G. When an initial stage crack occurs at the point P in the glass plate G being polished, the elastic wave from the point P propagates through the glass plate G as shown by the broken line in the figure, and then the polishing pad into which the slurry has penetrated After propagating to 20, it propagates to plate 18 and is detected by AE sensor 34.

  The polishing pad 20 is usually made of urethane, and the urethane itself hardly transmits an elastic wave, but the slurry penetrates into the urethane polishing pad 20. Therefore, the elastic wave from the point P is reliably detected by the AE sensor 34 from the slurry via the plate 18.

On the other hand, the AE sensor 34 is formed on the plate 18 as shown in FIG. 1 and attached to the lower surface of the protruding piece 18A that protrudes laterally from the polishing surface plate 22. When the AE sensor 34 is attached to the lower surface of the protruding piece 18A of the plate 18 projecting laterally from the polishing surface plate 22 in this way, the rotating polishing head 16 can be prevented from colliding with the AE sensor 34.
Although FIG. 1 illustrates the case where the number of AE sensors is one, as described above, the number of AE sensors to be attached is preferably determined as appropriate according to the size of the glass plate.

  Further, as a mounting position of the AE sensor 34, as shown in FIG. 6, a through hole 22A is formed in the central portion of the polishing surface plate 22, and the detection surface of the AE sensor 34 indicated by a two-dot chain line through the through hole 22A. 34A may be attached to the lower surface of the plate 18. If the AE sensor 34 is attached to the central portion of the polishing surface plate 22 in this way, the distance between the break position of the glass plate G and the AE sensor 34 can be shortened. By taking such an arrangement, the detection sensitivity of the elastic wave is improved.

  Further, the frequency band output from the AE sensor 34 to the abnormality detection unit 36 is set to a range of 100 to 200 kHz by the discriminator (filter) 42. Various devices such as a glass plate G cutting device, a chamfering device, and a drilling device are installed around the polishing device 10, and an elastic wave having a frequency (less than 100 kHz) caused by mechanical vibration from these devices. In addition, it is necessary to eliminate elastic waves having a frequency (over 200 kHz) due to electrical noise.

  Therefore, in the polishing apparatus 10 according to the embodiment, since the lower limit value of the frequency band output from the AE sensor 34 to the abnormality detection unit 36 is 100 kHz, erroneous detection due to the elastic wave of the mechanical vibration can be prevented. Further, since the upper limit value is set to 200 kHz, it is possible to prevent erroneous detection due to the elastic wave of the electrical noise. Note that the higher the upper limit value, the less the output of the AE sensor 34 is attenuated. Further, the AE sensor itself may incorporate a filter for extracting the frequency in the frequency band.

  The present invention is not limited to the above-described embodiments, and can be applied to substrate processing of electronic devices other than FPD, for example, glass substrates for optical elements, glass disks, solar cells and the like.

  In the embodiment, the polishing pad 20 is illustrated as the polishing tool, and the glass plate G is illustrated as the object to be polished. However, the present invention is not limited thereto, and the polishing tool is a truing grindstone (planar electrodeposition diamond). The present invention can also be applied to an apparatus for truing the polishing pad 20 with a truing grindstone using a polishing plate as a plate) and an object to be polished as the polishing pad 20. Since the configuration of this apparatus replaces the glass plate G with a truing grindstone in FIG. 2, the illustration is omitted here.

  When the polishing pad 20 is trued, water is used as the polishing liquid, and an elastic wave generated from the polishing pad 20 during truing passes through the water and is detected by the AE sensor 34. Information from the AE sensor 34 is always output to the abnormality detection unit 36, and the abnormality detection unit 36 is preset with a threshold value of the appropriate truing efficiency lower limit of the polishing pad 20. When the abnormality detection unit 36 detects a decrease in the truing efficiency of the polishing pad 20, the alarm 38 issues a warning.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2008-317269 filed on Dec. 12, 2008, the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Polishing apparatus 14 Holding member 16 Polishing head 18 Plate 20 Polishing pad 22 Polishing surface plate 22A Through hole 24 Polishing liquid supply hole 26 Suction hole 28 Spindle 30 Rotating / elevating device 32 Control unit 34 AE sensor 34A Detection surface 36 Abnormality detection unit 38 Alarm 40 Preamplifier 42 Discriminator 44 PLC cable 46 Cover 48 Cover 48A Top plate 48B Mounting part 48C Nut part

Claims (17)

A polishing apparatus that relatively presses and moves a polishing tool and an object to be polished, and polishes the object to be polished by the polishing tool while supplying a polishing liquid between the polishing tool and the object to be polished,
An AE sensor attached to a plate that supports a polishing tool or an object to be polished;
An abnormality detection unit that detects an abnormality during polishing based on an output signal from the AE sensor when an elastic wave from the object to be polished is detected by the AE sensor;
A polishing apparatus comprising: warning means for issuing a warning when an abnormality of the object to be polished is detected by the abnormality detection unit.   The polishing apparatus according to claim 1, wherein the polishing tool is a polishing pad, and the object to be polished is a glass plate.   The polishing apparatus according to claim 1, wherein the polishing tool is a truing grindstone, and the object to be polished is a polishing pad.   The polishing apparatus according to claim 2, wherein when the abnormality detection unit detects an abnormality of the glass plate, the polishing apparatus is stopped by a control unit that controls the polishing apparatus.   The polishing apparatus according to claim 2 or 4, wherein the AE sensor detects an elastic wave from the glass plate from the polishing liquid that has permeated the polishing pad via the plate. The polishing pad is held by a polishing platen through the plate,
6. The polishing according to claim 2, wherein the AE sensor is attached to a lower surface of a protruding piece formed on the plate and projecting laterally from the polishing surface plate. apparatus.   The polishing apparatus according to claim 2, wherein a frequency band output from the AE sensor to the abnormality detection unit is set in a range of 100 to 200 kHz by a filter.   The polishing apparatus according to claim 1, wherein an elastic wave from the object to be polished passes through the polishing liquid and is detected by the AE sensor. A polishing method in which a polishing tool and an object to be polished are relatively pressed and moved, and an object to be polished is polished by the polishing tool while supplying a polishing liquid between the polishing tool and the object to be polished,
An AE sensor is attached to a plate that supports a polishing tool or an object to be polished,
Based on the output signal from the AE sensor when the elastic wave from the object to be polished is detected by the AE sensor, the abnormality detection unit detects an abnormality during polishing,
A polishing method characterized in that a warning means issues a warning when an abnormality of an object to be polished is detected by the abnormality detection unit.   The polishing method according to claim 9, wherein the polishing tool is a polishing pad, and the object to be polished is a glass plate.   The polishing method according to claim 9, wherein the polishing tool is a truing grindstone, and the object to be polished is a polishing pad.   The polishing method according to claim 10, wherein when the abnormality of the glass plate is detected by the abnormality detection unit, the polishing apparatus is controlled by the control unit to stop the polishing apparatus.   The polishing method according to claim 10 or 12, wherein the AE sensor detects an elastic wave from the glass plate through the plate from the polishing liquid that has penetrated the polishing pad. The polishing pad is held by a polishing platen through the plate,
14. The polishing according to claim 10, wherein the AE sensor is attached to a lower surface of a protruding piece formed on the plate and projecting laterally from the polishing surface plate. Method.   The polishing method according to claim 10, wherein a frequency band output from the AE sensor to the abnormality detection unit is set in a range of 100 to 200 kHz by a filter.   The polishing method according to claim 9, wherein an elastic wave from the object to be polished passes through the polishing liquid and is detected by the AE sensor.   The manufacturing method of a glass plate characterized by processing a glass plate using the grinding | polishing method of any one of Claim 9,10,12-16.

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