JP2010243381A - Glass plate evaluation method based on electrification characteristic, glass plate production method using the same, and device for evaluation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve evaluation accuracy of electrification characteristics for glass plate. <P>SOLUTION: In the glass plate evaluation method, a peeling cycle containing a step of putting a glass plate on a table and a step of picking up it therefrom is repeated, at least until increase in absolute value of surface potential accompanied by increase in peeling cycle times is maintained; and the electrification characteristics of the glass plate are evaluated to be low in a case that (i) the peeling cycle is further repeated, until the surface potential of the glass plate reaches a saturation electrification potential and the absolute value of the saturation electrification potential is less than a reference value A, or (ii) the value of the increment of the absolute value of the surface potential during the period of maintaining increase of the absolute value of the surface potential divided by the peeling cycle times during the period is less than a reference value B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for evaluating a glass plate based on chargeability, a method for producing a glass plate using the same, and an apparatus used for the evaluation.

  A glass plate is used as a substrate of a flat panel display (FPD) such as a liquid crystal display or a plasma display. In the manufacturing process of FPD, there is a process of placing a glass plate on a table of a conveying device or a processing device or lifting it from the table, and this is an insulator along with contact and peeling between the table and the glass plate. Static electricity accumulates on the glass plate. If the amount of charge on the glass plate is excessive, an obstacle (electrostatic breakdown) is likely to occur in an electronic circuit or the like formed on the substrate. For this reason, there is a demand for a glass sheet with low chargeability in which static electricity is unlikely to accumulate due to contact with the table and peeling. In order to develop a glass plate with low chargeability, or to confirm whether the manufactured glass plate passes a predetermined standard for chargeability, it is necessary to accurately evaluate the chargeability of the glass plate.

  Japanese Patent Application Laid-Open No. 2005-255478 discloses an invention relating to a glass plate that is less likely to be charged due to contact with and peeling from the table. In paragraphs [0027] to [0037], the table and the glass plate are disclosed. It is described that contact and peeling were repeated 5 times, and the maximum charge amount after peeling was accumulated 5 times, and the charging property of the glass plate was evaluated based on the result.

JP 2005-255478 A

  The present inventor has noticed that the conventional evaluation method as described in JP-A-2005-255478 may not be able to properly evaluate the chargeability of the glass plate. Such a malfunction may be caused by a surface potential (initial potential) that may exist on the glass plate before performing the contact and peeling operation with the table. An ionizer or the like is known as an instrument for performing static elimination treatment on a glass plate. However, even if the neutralization treatment with such an instrument is performed carefully, it is not easy to completely remove the initial potential of the glass plate.

  The present invention is carried out by repeating a peeling cycle including a placing step for placing a glass plate on a placing table and a separating step for separating the glass plate from the mounting table, and the measurement is performed while repeating the peeling cycle. A glass plate evaluation method for evaluating a glass plate on the basis of a surface potential of the glass plate, wherein the peeling cycle includes at least an increase in absolute value of the surface potential accompanying an increase in the number of peeling cycles. I) The peeling cycle is further repeated until the surface potential of the glass plate reaches a saturated charging potential, and the absolute value of the saturated charging potential is larger than the reference value A. A small glass plate is evaluated as a glass plate with low chargeability, or ii) the absolute value of the surface potential over a period in which the increase in the absolute value of the surface potential lasts The glass plate having a value obtained by dividing the increase amount by the number of peeling cycles performed within the period is smaller than the reference value B is evaluated as a glass plate having low chargeability. Provide an evaluation method.

  In the present specification, the state in which “the increase in the absolute value of the surface potential is sustained” is a state in which the absolute value of the surface potential of the glass plate continuously increases over a predetermined number of peeling cycles, more specifically, The relationship that the absolute value of the surface potential in the n-th peeling cycle is larger than the absolute value of the surface potential in the (n-1) -th peeling cycle (where n is an integer) is at least 50 times, preferably 100 times or more. It means a state that persists over the peeling cycle. Further, in this specification, the saturated charging potential of the glass plate means the surface potential when the surface potential of the glass plate becomes substantially constant even when the number of peeling cycles is increased, and is more specific. Means the average value when the fluctuation of the surface potential in the at least 50 peeling cycles is in the range of −50V to 50V with respect to the average value of the surface potential in at least 50 peeling cycles.

  Moreover, this invention was equipped with the process of shape | molding several glass plates from the molten glass raw material from another side, and the process of evaluating the electrical charging property of these glass plates by using said evaluation method. A method for producing a glass sheet with low chargeability is provided.

  Further, the present invention is an evaluation device for evaluating the chargeability of a glass plate from yet another aspect, wherein the glass plate is mounted on the mounting table for mounting the glass plate and the mounting table described above. An elevating unit for placing and separating, a measuring unit for measuring the surface potential of the glass plate, a control unit for controlling the placing and separating of the glass plate by the elevating unit and the measurement of the surface potential by the measuring unit, A separation cycle including at least an operation of placing and separating the glass plate with respect to the mounting table while the measurement unit causes the measurement unit to measure the surface potential. Data to be used for comparison with reference data for controlling the elevating unit to be repeated until the increase in absolute value of the surface potential accompanying the increase continues and controlling the charging property of the glass plate. A calculation unit that calculates based on the surface potential; i) while the control unit causes the measurement unit to measure the surface potential, the peeling cycle is further repeated until the surface potential reaches a saturated charging potential The control unit controls the lift unit, and the calculation unit calculates the absolute value of the saturated charging potential as the data, or ii) the calculation unit increases the absolute value of the surface potential as the data There is provided an evaluation apparatus that calculates a value obtained by dividing an increase amount of the absolute value of the surface potential over a period in which the period is maintained by the number of peeling cycles performed in the period.

  In the present invention, at least an increase in the absolute value of the surface potential of the glass plate with an increase in the number of peeling cycles is maintained in the peeling cycle including the step of placing the glass plate on the mounting table and the step of separating the glass plate. Until then, it was decided to repeat. By repeating the peeling cycle to the above extent, it is applicable to the evaluation of charging properties, and a physical quantity independent of the initial potential can be measured, so that the charging properties of the glass plate can be evaluated more accurately than before.

It is a conceptual diagram for demonstrating the structure of the evaluation apparatus of the glass plate by this invention. It is sectional drawing which shows the structure of the mounting base vicinity in the apparatus of FIG. It is a figure for demonstrating the raising / lowering operation | movement of the glass plate in the apparatus of FIG. It is a graph which shows the relationship between the peeling cycle number in Sample A, and surface potential. It is a graph which shows the relationship between the peeling cycle number in Sample B, and surface potential.

  FIG. 1 is a conceptual diagram for explaining a configuration of an evaluation apparatus according to the present invention, FIG. 2 is a cross-sectional view showing a structure near a mounting table 10 in the evaluation apparatus 100, and FIG. It is a figure for demonstrating the raising / lowering operation | movement of the board 200. FIG. As shown in FIG. 1, the evaluation apparatus 100 includes a mounting table 10 on which a glass plate 200 is placed, an elevating unit 11, a measuring unit 12, a control unit 13, a calculation unit 14, and a display unit 15.

  As shown in FIG. 2, the elevating unit 11 protrudes toward the glass plate 200 (upward in FIG. 2), the elevating shaft 16 that can move up and down, the elevating plate 17 attached to the upper end of the elevating shaft 16. As shown, the lift plate 17 has a plurality of lifter pins 18 arranged on the upper surface of the lift plate 17. The glass plate 200 is lifted upward from the mounting table 10 by the elevating unit 11 from the state of being mounted on the mounting table 10, and then lowered and mounted again on the mounting table 10. The vertical movement of the lifting shaft 16 is controlled by the control unit 13. A through hole 20 is formed in the board portion 19 of the mounting table 10, and when the elevating shaft 16 is moved so that the elevating plate 17 approaches the board portion 19 of the mounting table 10, the upper end of the lifter pin 18 becomes the through hole. It moves through 20 and protrudes from the board part 19.

  When the separation step of separating the glass plate 200 from the mounting table 10 is performed, static electricity is generated in the glass plate 200 along with the separation of the glass plate 200 from the board portion 19. Static electricity is accumulated in the glass plate 200 by repeatedly performing a peeling cycle including a placement step for placing the glass plate 200 on the placement table 10 and a separation step.

  The board part 19 of the mounting table 10 is made of a metal typified by aluminum, and the surface of the board part 19 that contacts the glass plate 200 is subjected to an insulation process typified by anodizing. The lifter pin 18 is formed of a metal typified by aluminum, and an upper end portion to be brought into contact with the glass plate 200 is covered with an insulating material typified by resin. A suction hole (not shown) is formed in the board portion 19 of the mounting table 10, and the board portion 19 can be used as a suction plate for sucking and fixing the glass plate 200 to the mounting table 10 through the suction hole. Function.

  As shown in FIG. 1, the measurement unit 12 includes a measurement probe 12 ′ for measuring the surface potential of the glass plate 200. As shown in FIG. 2, the measurement probe 12 ′ is disposed at a position away from the surface 21 of the glass plate 200 by a predetermined distance (distance d). The measurement unit 12 is fixed to the lift plate 17 of the lift unit 11 via an arm 30. As a result, as shown in FIG. 3, the measurement probe 12 ′ moves up and down with respect to the board portion 19 of the mounting table 10 as the lifting plate 17 moves up and down. The distance d between the surface 21 and the measurement probe 12 'is kept constant. The measured value of the surface potential of the glass plate 200 measured through the measurement probe 12 ′ can vary depending on the distance d. However, in the evaluation apparatus 100 of the present invention, the distance d is kept constant as described above. Therefore, it is possible to avoid the occurrence of measurement failures due to such fluctuations.

  While the control unit 13 causes the measurement unit 12 to measure the surface potential of the glass plate 200, the peeling cycle of the glass plate 200 is at least until the increase in the absolute value of the surface potential accompanying the increase in the number of peeling cycles continues. The operation of the elevating unit 11 is controlled to be repeated. After the glass plate 200 is separated from the mounting table 10, more specifically, after the glass plate 200 is separated from the mounting table 10, the control unit 13 is mounted on the mounting table 10 by the next peeling cycle. By the time, the operation of the measurement unit 12 is controlled so that the surface potential of the glass plate 200 is measured. The surface potential measurement (measurement step) by the measurement unit 12 is preferably controlled to be performed at least once every peeling cycle, but may be controlled to be performed every predetermined number of peeling cycles. Good. The control unit 13 can also control the operation of the elevating unit 11 so that the peeling cycle is repeated until the surface potential of the glass plate 200 reaches the saturated charging potential.

  The surface potential of the glass plate 200 measured by the measurement unit 12 is input to the calculation unit 14 via the control unit 13. The calculation unit 14 should be used for comparison with reference data for evaluating the charging property of the glass plate based on the surface potential of the glass plate after repeatedly performing the peeling cycle. I) Saturated charging potential of the glass plate 200 And ii) a value obtained by dividing the amount of increase in the absolute value of the surface potential over a period in which the increase in the absolute value of the surface potential lasts is divided by the number of stripping cycles carried out in that period (surface At least one of the change rate of the absolute value of the potential). The change rate of the absolute value of the saturation charging potential and the absolute value of the surface potential is a physical quantity that does not depend on the initial potential. Note that the rate of change of the absolute value of the surface potential is calculated based on the absolute value of the surface potential in two peeling cycles performed 50 times or more apart. By using the absolute value of the surface potential in two peeling cycles separated as much as this as a reference, the influence of noise that can be mixed into the measured value of the surface potential can be almost ignored.

  The absolute value of the saturation charging potential and the change rate of the absolute value of the surface potential calculated by the calculation unit 14 are input to the display unit 15 via the control unit 13. The user of the evaluation apparatus 100 compares the change rate of the absolute value of the saturated charging potential and the absolute value of the surface potential displayed on the display unit 15 with the corresponding reference data values, thereby charging the glass plate 200. Can be evaluated. More specifically, when the change rate of the absolute value of the saturation charging potential and the absolute value of the surface potential is smaller than the value of the corresponding reference data, it is evaluated that the charging property is low. The reference value A, which is reference data corresponding to the absolute value of the saturated charging potential, may be set according to the use of the glass plate. For example, when a glass plate is used as an FPD substrate, it can be set to 2500V. . The reference value B, which is reference data corresponding to the rate of change of the absolute value of the surface potential, may be set according to the use of the glass plate and the implementation conditions of the peeling cycle. For example, a glass plate is applied as the substrate of the FPD, As shown in the Example mentioned later, when performing peeling cycle using the evaluation apparatus 100, it can set to 8V.

  The evaluation apparatus according to the present invention further includes an evaluation unit that evaluates the chargeability of the glass plate 200 by comparing the change rate of the absolute value of the saturated charging potential and the absolute value of the surface potential with the corresponding reference data. The absolute value of the saturation charging potential and the rate of change of the absolute value of the surface potential are input to the evaluation unit from the unit 14 via the control unit 13, and a signal regarding the evaluation of chargeability is input to the display unit 15 via the control unit 13. The evaluation result may be displayed on the screen of the display unit 15. When the evaluation apparatus includes an evaluation unit, it is desirable that the user can select at least one of the reference value A and the reference value B as the reference data used for the evaluation of the chargeability.

  The method for evaluating a glass plate according to the present invention will be described by taking as an example the case of using the evaluation apparatus 100. First, the glass plate to be evaluated is mounted on the mounting table 10 and is sucked and fixed to the board portion 19 through the suction holes. The glass plate 200 is preferably subjected to a charge removal process using a known ionizer immediately after being placed on the placing table 10. In addition, when performing a static elimination process, it implements only when the glass plate 200 is mounted in the mounting base 10 initially.

  Next, in a state where the suction fixation is stopped, the elevating unit 11 is driven, and the glass plate 200 is lifted upward from the mounting table 10 while being supported by the upper end of the lifter pin 18. Then, the raising / lowering part 11 is lowered | hung, the glass plate 200 is again mounted in the mounting base 10, and the glass plate 200 is attracted and fixed to the mounting base 10 through a suction hole. Until the increase in the absolute value of the surface potential continues at least with the increase in the number of peeling cycles while performing the measurement step, the peeling cycle consisting of the placing step and the separating step of the glass plate 200 with respect to the placing table 10 In some cases, the process is repeated until the surface potential of the glass plate 200 reaches the saturated charging potential. Then, based on the surface potential of the glass plate 200 obtained in each measurement step, the measurement unit 14 calculates the absolute value of the saturation charging potential and the change rate of the absolute value of the surface potential.

  When the glass plate 200 has the initial potential, the absolute value of the surface potential measured from the glass plate 200 at the initial stage of the peeling cycle does not stably increase. As a result, the initial surface potential of the peeling cycle is increased. If used as an index, the chargeability of the glass plate may not be properly evaluated. However, by repeating the peeling cycle to the above extent, it is possible to specify the change rate of the absolute value of the saturated charging potential and the absolute value of the surface potential, which are physical quantities that do not depend on the initial potential. The absolute value of the saturated charging potential obtained from the glass plate 200 is a value inherent to the glass plate 200 determined by the composition and surface roughness (Ra) of the glass plate 200 and does not vary depending on the initial potential. The change rate of the absolute value of the surface potential obtained from the glass plate 200 is a combination of the glass plate 200 and the evaluation device 100, more specifically, the composition and surface roughness of the glass plate 200, and the board of the mounting table 10. The value is determined by the combination of the surface roughness (Ra) of the portion 19 and the constituent material, the peeling rate in the peeling cycle, and the like, and does not vary depending on the initial potential. For this reason, by using the change rate of the absolute value of the saturated charging potential and the absolute value of the surface potential as indices, the chargeability of the glass plate 200 can be appropriately evaluated regardless of the presence or absence of the initial potential. The charging property of the glass plate 200 is evaluated by comparing the rate of change of the absolute value of the saturated charging potential and the absolute value of the surface potential with the corresponding reference data.

  In the glass plate manufacturing process, surface potential can be generated in various processes. For example, the surface potential can be generated by contact between the glass plate and the roller and friction between the roller and the glass plate surface due to peeling in the process of forming the molten glass raw material into a plate shape and then transporting it with a roller conveyor or the like. Further, for example, surface potential can be generated by friction between the airflow and the glass plate surface in the step of washing and drying the glass plate.

  The glass plate to be evaluated may be prepared independently by molding a molten glass material, or may be prepared by obtaining a commercial product.

  In addition, although the aspect which evaluates a glass plate using the evaluation apparatus by this invention was demonstrated above, the evaluation method by this invention uses the apparatus which is not equipped with the calculating part 14, for example, and is saturated by the calculating part 14. Instead of calculating the absolute value of the potential and the change rate of the absolute value of the surface potential, the measured surface potential is output as numerical data outside the device, and based on the numerical data, the absolute value of the saturated charging potential and the absolute value of the surface potential The rate of change may be calculated by the user of the apparatus.

  According to the present invention, it is also possible to produce a glass plate, comprising a step of forming a plurality of glass plates from a molten glass raw material and a step of evaluating the chargeability of the plurality of glass plates by the evaluation method. it can. As a result, it is possible to confirm whether the molded glass plate has passed a predetermined standard for chargeability, or to select those that have passed the standard from a plurality of molded glass plates, A glass sheet with low chargeability can be provided more reliably.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Expressed in mass%, SiO ₂ : 60.9, B ₂ O ₃ : 11.6, Al ₂ O ₃ : 16.9, MgO: 1.7, CaO: 5.1, SrO: 2.6, BaO: 0.7, K ₂ O: 0.25, Fe ₂ O ₃ : 0.15, SnO ₂ : 0.13, and the surface roughness (Ra) is 0.2 nm and 0.5 nm. Two types of glass plates (680 mm × 880 mm, thickness 0.7 mm) were prepared. In the following description, among these glass plates, the surface having a surface roughness of 0.2 nm is referred to as sample A, and the surface having a surface roughness of 0.5 nm is referred to as sample B. Note that it has been confirmed that Sample B has lower chargeability than Sample A.

  Sample A was melted at 1580 ° C using a continuous melting device equipped with a refractory brick melting tank and a platinum adjustment tank, clarified at 1650 ° C, and stirred down at 1500 ° C. After forming into a thin plate by the draw method, it was cut into a predetermined size and obtained by washing the surface. Sample B was subjected to the step of roughening the surface by immersing the glass plate in a glass etching solution containing hydrofluoric acid in a range of 120 seconds or less, and then cleaning the surface of the glass plate, Obtained in the same manner as Sample A. The surface roughness of the glass plate and the surface roughness (Ra) of the board portion of the mounting table described later were measured using an atomic force microscope.

  The evaluation apparatus 100 according to the present invention was installed in a clean room having class 1000 cleanliness, and the chargeability of the sample A and the sample B was inspected as described above. The surface roughness (Ra) of the board portion 19 of the mounting table 10 was 1.6 mm. The atmosphere in the clean room was controlled at a temperature of 20 ° C. and a relative humidity of 50%. As a measurement probe, 542-1 made by TREAK was used. The distance d between the measurement probe and the glass plate was set to 25 mm. The distance for lifting the glass plate from the mounting table was set to 50 mm. The neutralization process was performed using a known ionizer (SJ-H060, manufactured by Keyence Corporation) until the absolute value of the surface potential of the glass plate was not reduced even after the neutralization process was continued. In the peeling cycle, the glass plate at a position lifted by 50 mm from the mounting table is 3 seconds for the lifter pin to be lowered and mounted on the mounting table, and the glass plate is sucked and fixed to the mounting table for 3 seconds. The time for stopping the suction and aligning the glass plate for 2 seconds, the time for raising the lifter pin to lift the glass plate to the position 50 mm away from the mounting table for 7 seconds, and the time for aligning the glass plate after rising for 2 seconds It was carried out with setting. The alignment of the glass plate is an operation for adjusting the positional deviation of the glass plate due to the lifting and lowering operations of the lifter pin. The surface potential of the glass plate is measured every 2.95 seconds, and the data obtained after the glass plate is separated from the mounting table and until it is mounted on the mounting table by the next peeling cycle. The thing with the largest difference from 0V was extracted as the surface potential in each peeling cycle.

  4 and 5 are graphs showing fluctuations in the surface potential accompanying the repetition of the peeling cycle in Sample A and Sample B. FIG. As shown in FIGS. 4 and 5, in any sample, in the initial stage of the peeling cycle repetition (for example, the degree of repeating the peeling cycle 5 to 10 times), the absolute surface potential is caused by the initial potential. The value did not increase stably. However, in any sample, when the peeling cycle was further repeated, the absolute value of the surface potential increased almost linearly from the time when the number of repetitions exceeded 25.

  The absolute value of the saturation charging potential of Sample A was 7134V, and the absolute value of the saturation charging potential of Sample B was 2322V. The absolute value of the saturated charging potential of sample A and sample B is the average value of the absolute value of the surface potential in the peeling cycle carried out over a predetermined period immediately after the increase in the absolute value of the surface potential of the glass plate no longer continues. More specifically, as the average value of the absolute values of the surface potential in the peeling cycle from the 377th to the 428th time for the sample A, and for the peeling cycle from the 351st time to the 403th time for the sample B, Calculated. The fluctuation of the surface potential in the peeling cycle during the period was in the range of −50V to 50V. The surface potentials in the 119th and 237th peeling cycles were −2540V and −5005V for sample A, and −855V and −1565V for sample B, respectively. The rate of change of the absolute value of the surface potential was calculated based on these data. As a result, it was 20.9 V for sample A and 6.0 V for sample B.

  Thus, Sample B, which is a glass plate that is difficult to be charged, had a change rate of the absolute value of the surface potential in a range of less than 8V, and an absolute value of the saturation charge potential in a range of less than 2500V.

DESCRIPTION OF SYMBOLS 10 Mounting stand 11 Lifting part 12 Measuring part 12 'Measuring probe 13 Control part 14 Calculation part 15 Display part 16 Lifting shaft 17 Lifting plate 18 Lifter pin 19 Board part 20 of mounting base 21 Through hole 21 On the opposite side to a mounting base in a glass plate Surface 30 Arm 100 Glass plate evaluation device 200 Glass plate

Claims (3)

The glass plate measured by repeating a peeling cycle including a placing step of placing a glass plate on the placing table and a separating step of separating the glass plate from the mounting table, and repeating the peeling cycle. A glass plate evaluation method based on the surface potential of the glass plate,
The stripping cycle is repeated at least until the increase in the absolute value of the surface potential with the increase in the number of stripping cycles continues,
i) The peeling cycle is further repeated until the surface potential of the glass plate reaches a saturation charging potential, and a glass plate having an absolute value of the saturation charging potential smaller than the reference value A is low in chargeability. Evaluate as a glass plate, or ii) by dividing the amount of increase in absolute value of the surface potential over a period where the increase in absolute value of the surface potential lasts by the number of stripping cycles performed within that period A glass plate whose value is smaller than the reference value B is evaluated as a glass plate with low chargeability.
Evaluation method of glass plate.   The manufacturing method of a glass plate provided with the process of shape | molding a several glass plate from the fuse | melted glass raw material, and the process of evaluating the electrical charging property of these glass plates by the evaluation method of Claim 1. An evaluation device for evaluating the chargeability of a glass plate,
A mounting table for mounting a glass plate, a lifting unit for mounting and separating the glass plate with respect to the mounting table, a measuring unit for measuring a surface potential of the glass plate, and the glass plate by the lifting unit A control unit for controlling the mounting and separation of the surface and the measurement of the surface potential by the measurement unit,
While the control unit causes the measurement unit to measure the surface potential, at least a peeling cycle including an operation of placing and separating the glass plate with respect to the mounting table is accompanied by an increase in the number of peeling cycles. Controlling the elevating part to be repeated until the increase in absolute value of the surface potential continues,
A calculation unit that calculates data to be used for comparison with reference data for evaluating the charging property of the glass plate based on the surface potential, and
i) The control unit controls the elevating unit so that the peeling cycle is further repeated until the surface potential reaches a saturated charging potential while causing the measurement unit to measure the surface potential, Ii) calculating the absolute value of the saturated potential as the data, or ii) increasing the absolute value of the surface potential over a period in which the increase in the absolute value of the surface potential continues as the data. A value obtained by dividing by the number of stripping cycles performed within the period,
Evaluation device.

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