JP2013076623A - Flatness measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flatness measuring method capable of accurately finding out flatness of a surface of a measuring object.SOLUTION: In the flatness measuring method, a laser measuring apparatus including a laser displacement meter, while scanning a laser beam, measures and inputs information on distances in an irradiation direction of the laser beam between the surface of the measuring object and a liquid level to be a measurement reference surface at a plurality of positions. Then, the distance information at the plurality of positions measured by the laser displacement meter and the position information of the plurality of positions scanned by the laser displacement meter are inputted to a computer. The computer calculates the flatness by searching such target parallel planes that, when measurement data expressing the position information and the distance information at respective measured positions as coordinates are expressed by points on a coordinate space, all points are held between two parallel planes and a distance between the two parallel planes is minimum, while changing an inclination of the two parallel planes.

Description

  The present invention relates to a flatness measuring method for measuring the flatness of a surface of a measurement object.

  As a glass substrate used for a flat panel display (hereinafter referred to as “FPD”) such as a liquid crystal display or a plasma display, a thin glass plate having a thickness of, for example, 0.5 to 0.7 mm is used. For example, the FPD glass substrate has a size of 300 × 400 mm in the first generation, but has a size of 2850 × 3050 mm in the tenth generation.

  The overflow downdraw method is most often used to manufacture such a large glass substrate for FPD of the eighth generation or later. The overflow downdraw method includes a step of forming a sheet glass below the formed body by causing the molten glass to overflow from the upper part of the formed body in a forming furnace, and a step of gradually cooling the sheet glass in a slow cooling furnace. The slow cooling furnace draws the sheet glass between the pair of rollers and stretches the sheet glass to a desired thickness, and then slowly cools the sheet glass so as to reduce internal distortion and thermal shrinkage of the sheet glass. Thereafter, the plate-like glass is cut into a predetermined size to form a glass plate, which is laminated and stored on another glass plate. Or a glass plate is conveyed by the following process. The overflow downdraw method is described in Patent Document 1 below, for example.

  It is desired that a molded body used in such a downdraw method is produced with high accuracy and that the surface of the molded body has high flatness. This is because the molten glass flows on the surface of the molded body, so that the glass sheet is accurately formed so as to have the target thickness and the thickness does not vary depending on the location. This is to prevent unevenness.

On the other hand, there is known a practical flatness measuring device that uses the liquid level as a reference plane as a measurement reference and improves measurement operability and has few restrictions on the measurement target as well as improving measurement accuracy. (Patent Document 2).
The flatness measuring device is provided with a flatness measuring device main body movable along the surface to be measured, and a liquid tank that forms a reference liquid surface that becomes a quasi-ideal plane independently from the flatness measuring device main body, The flatness measuring device main body is equipped with a copying means for mechanically copying the surface to be measured and an optical displacement sensor for measuring the vertical movement with respect to the reference liquid surface so as to be movable up and down. The flatness of the surface to be measured is measured by measuring.

JP 2009-196879 A JP 2008-224322 A

  However, since the flatness measuring apparatus performs measurement using a copying unit that mechanically follows the surface to be measured, it may not be possible to obtain a highly accurate measurement result. Further, in the flatness measuring apparatus, it is necessary to match the position of the contact point of the measuring wheel, which is a copying means, with the measuring point on the liquid surface with respect to the vertical axis in order to increase the measurement accuracy. However, when the surface to be measured of the measurement object is inclined like a molded body, the contact point of the measurement wheel is not located on the vertical axis passing through the measurement point on the liquid level in the inclined surface to be measured. Therefore, there are cases where it is impossible to measure with high accuracy.

  Therefore, an object of the present invention is to provide a flatness measurement method capable of accurately obtaining the flatness of the surface of a measurement object using a method different from that of the prior art.

One embodiment of the present invention is a flatness measurement method for measuring the flatness of a surface of a measurement object.
The method is
Information on the distance in the irradiation direction of the laser light between the surface of the measurement object and the liquid surface as the measurement reference surface at a plurality of positions while the laser measuring device including the laser displacement meter scans the laser light Measuring and capturing
The computer captures the distance information at the plurality of positions measured by the laser displacement meter and the position information of the plurality of positions scanned by the laser displacement meter, and the computer captures the position information at each of the measured positions. When the measurement data representing the distance information as coordinates is represented by points on the coordinate space, all the points are sandwiched between two parallel planes, and the distance between the two parallel planes is the minimum. And searching for a target parallel plane, while changing the inclination of the two parallel planes, to calculate the flatness.

  In the flatness measuring method of the said form, the flatness of the surface of a measuring object can be calculated | required accurately.

It is a figure explaining the outline | summary of the system which implements the flatness measuring method of this embodiment. It is a figure explaining the structure of the laser displacement meter of a laser focus system used with the system shown in FIG. It is a figure which shows the structure of the data processor used with the system shown in FIG. (A)-(c) is a figure explaining the calculation method of the distance between parallel planes calculated | required in the flatness measuring method of this embodiment, and the calculation method of flatness. It is a figure which shows the flow of an example of the flatness measuring method of this embodiment. (A) is an external appearance perspective view of the molded object used for this embodiment, (b) is a figure which shows the state of the molten glass which flows through a molded object when shape | molding sheet glass from molten glass.

Hereinafter, the flatness measurement method of this embodiment will be described.
FIG. 1 is a diagram for explaining the outline of a system 10 that implements the flatness measurement method of the present embodiment.
The system 10 mainly includes a laser measurement device 12, a data processing device 14, and a water tank 16. A molded body 18 for molding a sheet glass, which will be described later, which is an object to be measured, is submerged in a water tank 16 in which a liquid having transparency such as water is stored, and is placed in the liquid. In this embodiment, although the molded object 18 is used as a measuring object, a glass plate can also be used. Moreover, objects other than the molded object 18 and a glass plate can also be used for a measurement object.

The laser measuring device 12 measures the distance between the surface of the molded body 18 and the liquid level as the measurement reference surface. For example, the laser measuring device 12 measures the distance between the surface of the molded body 18 and the liquid surface separately using two laser displacement meters of the laser focus method. FIG. 2 is a diagram for explaining the configuration of a laser displacement meter of the laser focus method. The laser focus method includes a laser light source 12a, a half mirror 12b, a collimator lens 12c, a focus lens 12d, a pinhole 12e, and a light receiving element 12f. The laser light L emitted from the laser light source 12a is transmitted through the half mirror 12b and converted into parallel light by the collimator lens 12c, and then the light beam is focused by the focus lens 12d and irradiated onto the surface of the measurement object. . The reflected light reflected from the surface of the measurement object passes through the focus lens 12d and the collimating lens 12c, is reflected by the half mirror 12b, and then passes through the pinhole 12e. However, only when the laser beam is focused on the surface of the measurement object, it passes through the pinhole 12e and is received by the light receiving element 12f. Therefore, the position of the focus lens 12d is changed until the maximum light receiving signal is obtained by the light receiving element 12f. As a result, the distance between the position of the focus lens 12d and the surface of the object to be measured can be obtained from the position of the focus lens 12d when the light reception signal becomes maximum, and measurement is performed from the laser light source 12a using this distance. The distance to the surface of the object can be measured. The laser focus method is a well-known method as disclosed in, for example, the following addresses.
1317345340658_0.html
(Search on September 14, 2011)
In this embodiment, a laser focus type laser displacement meter is used, but in addition to this, a known triangulation type laser displacement meter can also be used. The laser displacement meter of the triangulation system is disclosed at the following address, for example.
1317345340658_1.html
(Search on September 14, 2011)
In the present embodiment, two laser displacement meters are used, but if the measurement of the distance between the surface of the molded body 18 and the liquid surface as the measurement reference surface can be measured using one laser displacement meter, One laser displacement meter can also be used.

  The laser measurement device 12 measures the distance between the surface of the molded body 18 that is a measurement object and the liquid surface 16a that is the measurement reference surface. Specifically, the laser measurement device 12 scans the laser beam L of the laser displacement meter relative to the molded body 18 and the liquid surface 16a, and at a plurality of measurement positions, the laser beam L is measured. The distance between the surface and the liquid level 16a as the measurement reference surface is measured. In the relative scanning, the laser beam L may be moved with respect to the molded body 18 and the liquid surface 16a, or the laser beam L may be moved with the molded body 18 and the liquid surface 16a fixed. The molded body 18 and the liquid surface 16a may move while the laser beam L is fixed. However, scanning in which the laser light L moves in a state where the molded body 18 and the liquid surface 16a are fixed is preferable in terms of preventing the liquid surface 16a from wavy. As shown in FIG. 1, the surface of the molded body 18 is two-dimensionally scanned while moving the laser light L in the X and Y directions of the liquid surface 16a as shown in FIG. This is preferable. The laser measuring device 12 has information on the scanning position of the laser beam L at all measured positions, specifically, the X coordinate that is the position coordinate in the X direction on the liquid surface 16a, and the position in the Y direction on the liquid surface 16a. The position information of the Y coordinate, which is the coordinates, and the distance information in the irradiation direction of the laser light L obtained by measurement (the information of the distance between the surface of the molded body 18 and the liquid surface) are supplied to the data processing device 14. To do. That is, the laser measurement device 12 supplies the data processing device 14 with the information on the distance measured by the laser displacement meter and the position information on the measurement position scanned by the laser displacement meter.

The data processing device 14 is configured by a software module formed on a computer by reading software recorded in a memory in the data processing device 14.
FIG. 3 is a diagram illustrating a configuration of the data processing device 14. The data processing device 14 is a computer having a CPU 14a, a memory 14b, and an input / output unit 14c. The input / output unit 14c of the computer is connected to the laser measuring device 12 and to an output device 15 such as a printer or a display.
The memory 14c stores a program for executing data processing (to be described later) performed in the present embodiment. When the computer calls and executes this program, the processing control unit 14d, the data selection unit 14e, and the plane calculation unit 14f are recorded. A distance calculation unit 14g and a flatness calculation unit 14h are formed. That is, the process control unit 14d, the data selection unit 14e, the plane calculation unit 14f, the distance calculation unit 14g, and the flatness calculation unit 14h are software modules that function by execution of a computer. Accordingly, the calculation of these parts is substantially handled by the CPU 14a. The memory 14b records the distance information and the position information of the measurement position supplied from the laser measurement device 12 as measurement data.

The process control unit 14d is a part that instructs and controls each process associated with the calculation of flatness described later. For example, the process control unit 14d determines whether or not selection of a set of three coordinate data representing three points satisfies a predetermined condition, and calculates a parallel plane distance described later until the determination result is affirmative. The operation is controlled by giving an instruction to each part so as to repeat.
The data selection unit 14e selects a set of three coordinate data. These three coordinate data are used to calculate a plane as will be described later. The selected coordinate data is coordinate data in the XYZ coordinate space including the X coordinate in the X direction and the Y coordinate in the Y direction shown in FIG. 1 and the Z coordinate in the Z direction that is the irradiation direction of the laser light of the laser displacement meter. . The method of selecting the three coordinate data is not particularly limited. For example, a method of selecting three coordinate data sets on the XYZ coordinate space at random, or coordinate data of three data sets from measurement data. The method of selecting may be used. Also, selection of a set of three coordinate data such that the inclination of two parallel planes to be described later is a preset inclination and the inclination angle changes by a certain angle each time selection is repeated as will be described later. It may be.
The plane calculation unit 14f calculates a plane from the three selected coordinate data. This plane is a plane determined by using these three points when the three coordinate data values are three points on the coordinate space represented as coordinate values.

The distance calculation unit 14g creates two parallel planes P ₁ and P ₂ by translating the plane determined by the plane calculation unit 14f in different directions, and the two parallel planes P ₁ and P ₂ are measured data. The shortest distance between all the points represented in the XYZ coordinate space is calculated by the value of. This distance is called the distance between parallel planes. The distance calculation unit 14g records the calculated distance between parallel planes in the memory 14b, and also calculates the distance between the parallel planes calculated this time and has already calculated and recorded in the memory 14b as the minimum distance between the parallel planes. Compare with When the distance between parallel planes calculated this time is smaller than the flatness candidate, the distance calculation unit 14g updates the parallel plane distance as a flatness candidate and records it in the memory 14b. If the flatness candidate recorded in the memory 14b is less than or equal to the distance between the parallel planes calculated this time, the flatness candidate is maintained as it is. Thus, the distance calculation unit 14g sets the flatness candidate.
When the distance calculation unit 14g calculates the distance between the parallel planes for the first time, since the flatness candidate is not recorded in the memory 14b, the calculated distance between the parallel planes is set as the flatness candidate for the first time, and is stored in the memory 14b. To be recorded.

4A to 4C are diagrams illustrating the calculation of the distance between parallel planes and the calculation of flatness. For example, a point on a three-dimensional coordinate space in which measurement data including position information of measurement data and distance information at the measured position as X coordinates, Y coordinates, and Z coordinates is used as each coordinate axis. Represented by In this case if the surface P ₀ with gentle irregularities as shown in FIG. 4 (a) by a point on the coordinate space is formed, two parallel planes P _1, such as to sandwich all the irregularities of the surface P ₀ , P ₂ , the parallel planes are determined so that the distance between the parallel planes is the shortest. Example shown in FIG. 4 (b), the distance calculating unit 14g is shows how to calculate the parallel plane distance D ₁ as the shortest distance of the plane distance. However, in the example of FIG. 4B, since the directions of the planes P ₁ and P ₂ are not planes along the inclination of the plane P ₀ , the parallel plane distance D ₁ does not become flatness.
Such calculation of the distance between the parallel planes is performed every time a new set of three coordinate data is selected by the data selection unit 14e.

The flatness calculation unit 14h obtains the flatness candidate stored in the memory 14b as the flatness based on an instruction from the process control unit 14d. The instruction of the processing control unit 14d is sent to the flatness calculation unit 14h when selection of a set of three coordinate data representing three points satisfies a predetermined condition. The predetermined condition is, for example, whether or not the total number of selections exceeds a preset number of times, for example, 1 million, when using a method of selecting a set of three completely random coordinate data as described above. Say. Further, when using a method of selecting a set of three coordinate data from measurement data, for example, it means whether or not all combinations of three data are selected from all measurement data. A method of selecting three data sets so that the inclinations of the two parallel planes P ₁ and P ₂ are preset inclinations, and the inclination angle changes by a constant angle each time selection is repeated. Is used, it means whether or not the inclination of the _two parallel planes P ₁ and P ₂ has changed over the entire preset range, for example, the entire range of −180 degrees to +180 degrees.
As shown in FIG. 4 (c), the minimum distance D _min is a plan distance between inclined along such inclination with two parallel planes P _1, P ₂ of the surface P _0. Such two parallel planes are target parallel planes. Therefore, the flatness calculation unit 14h calculates the minimum distance _Dmin among the parallel plane distances as the flatness of the measurement target surface of the molded body 18.

As described above, in the system 10 of the present embodiment, when the measurement data is represented by a point in the XYZ coordinate space, all of the points are sandwiched between the two parallel planes, and between the two parallel planes. The degree of flatness is calculated by searching for a target parallel plane that minimizes the distance between the planes while changing the inclination of the two parallel planes. For this reason, this embodiment can calculate flatness with high accuracy by data processing.
The molded body 18 that is a measurement object is placed in a transparent liquid such as water, and the liquid level is the liquid level. Therefore, in the system 10 of this embodiment, since the liquid level becomes a horizontal plane, it is possible to calculate the flatness with high accuracy using the measurement based on the horizontal plane.

  In the present embodiment, the molded body 18 is placed in a liquid having transparency, such as water, and the liquid level is the level of the liquid. However, the molded body 18 may not be placed in a liquid having transparency. For example, a transparent container containing a transparent liquid is disposed between the laser displacement meter and the molded body 18, and the distance to the liquid level of the liquid in the container is measured with laser light and reflected light. In addition, the distance between the liquid surface and the surface of the molded body 18 may be measured by measuring the distance to the surface of the molded body 18 using laser light and reflected light that pass through the container and the liquid. it can.

FIG. 5 is a diagram showing a flow of the flatness measuring method of the present embodiment.
First, the laser measuring device 12 scans the laser beam L applied to the surface of the molded body 18 by the laser displacement meter, and the distance between the surface of the molded body 18 and the liquid surface as the measurement reference plane at a plurality of positions. Measure information. (Step S10). The position information and distance information obtained by the measurement are supplied to the data processing device 14.

  The data processing device 14 captures and records the position information and distance information supplied via the input / output unit 14c as measurement data in the memory 14b. Thereby, the measurement data is taken in by the computer (step S20).

  Next, the data selection unit 14e selects a set of three coordinate data (step S30). The method for selecting the three sets of coordinate data is not particularly limited, but the sets are selected so that at least the same set is not selected. The selection method may be a method of selecting a set of three coordinate data on the XYZ coordinate space at random, or a method of selecting coordinate data of a set of three data from measurement data. Further, this is a method of selecting a set of three coordinate data in which the inclinations of two parallel planes are inclinations set in advance and the inclination angle changes by a certain angle each time selection is repeated.

Next, the plane calculation unit 14f obtains two parallel planes P ₁ and P ₂ using the selected three coordinate data (step S40). Specifically, the plane calculation unit 14f determines a plane formed by three points on the XYZ coordinate space in which the values of the selected three coordinate data are expressed as coordinate values, and this plane is different from the plane perpendicular to the plane. Moving in two directions, planes P ₁ and P ₂ parallel to each other are obtained.

Next, the distance calculation unit 14g reduces the distance between the planes P ₁ and P ₂ , and all the points represented by the points in the XYZ coordinate space in which the values of all the measurement data are expressed as coordinate values are all in the plane P. _1, to calculate the parallel plane distance is the shortest distance to be sandwiched between P ₂ (step S50). This parallel plane distance is, for example, the parallel plane distance D ₁ in FIG. The calculated distance between parallel planes is recorded in the memory 14b.
Further, the distance calculation unit 14g compares the calculated distance between parallel planes with the flatness candidate previously calculated and recorded in the memory 14b as the minimum value of the parallel plane distance. When the distance between parallel planes calculated this time is smaller than the flatness candidate, the distance calculation unit 14g updates the parallel plane distance as a flatness candidate and records it in the memory 14b. If the flatness candidate recorded in the memory 14b is less than or equal to the distance between the parallel planes calculated this time, the flatness candidate is maintained as it is. Thus, the distance calculation unit 14g sets the flatness candidate (step S55). When the distance calculation unit 14g calculates the distance between the parallel planes for the first time, since the flatness candidate is not recorded in the memory 14b, the calculated distance between the parallel planes is set as the flatness candidate for the first time, and is stored in the memory 14b. To be recorded.

Next, the process control unit 14d determines whether or not the selection of the three-point coordinate data set satisfies a predetermined condition (step S60). The predetermined condition is, for example, whether or not the total number of selections exceeds a preset number of times, for example, 1 million, when using a method of selecting a set of three completely random coordinate data as described above. Say. Further, when using a method of selecting a set of three coordinate data from measurement data, for example, it means whether or not all combinations of three data are selected from all measurement data. A method of selecting three data sets so that the inclinations of the two parallel planes P ₁ and P ₂ are preset inclinations, and the inclination angle changes by a constant angle each time selection is repeated. Is used, it means whether or not the inclination of the _two parallel planes P ₁ and P ₂ has changed over the entire preset range, for example, the entire range of −180 degrees to +180 degrees.
If the result of the determination is negative (if NO), the process control unit 14d returns to step S30 and newly sets a coordinate data set different from the coordinate data set previously selected by the data selection unit 14e. Instruct to select.

  If the result of the determination is affirmative (if YES), the process control unit 14d instructs the flatness calculation unit 14h to obtain the flatness. Thereby, the flatness calculation unit 14h calls the flatness candidates set by the distance calculation unit 14g and recorded in the memory 14b, and obtains them as flatness (step S70). The obtained flatness is sent to the output device 15, and the flatness is displayed on the screen or printed out.

As described above, the data processing device 14 formed by the computer repeatedly performs the selection of the three coordinate data sets until a predetermined condition is satisfied, and each time this selection is performed, two data are selected from the selected three coordinate data. The parallel plane distances D _k (k = 1 to N) are obtained by calculating the parallel planes P ₁ and P _2, and when the selection of the three coordinate data satisfies a predetermined condition, the calculated parallel plane distances The minimum distance D _min among D _k is _obtained as flatness.
In this embodiment, the distance calculation unit 14g sets a flatness candidate every time the distance between parallel planes is calculated. However, the distance calculation unit 14g may not set the flatness candidate every time the distance between parallel planes is calculated. In this case, when the determination in step S60 is affirmative, the flatness calculating unit 14h obtains the minimum distance from the plurality of parallel plane distances recorded in the memory 14b each time the parallel plane distance is calculated. The minimum distance can be obtained as flatness.

  The surface of the measurement object used in the present embodiment is the surface of a molded body 18 that forms a sheet glass from molten glass by a downdraw method, and the surface of the molded body 18 is a surface through which the molten glass flows in the downdraw method. is there. It is desirable that the surface of the molded body 18 through which the molten glass flows has high flatness so as not to form irregularities on the glass plate. In this respect, in the system 10 of the present embodiment, it is effective to use the molded body 18 as a measurement object. However, the measurement object may be another object. For example, the surface of the measurement object may be the surface of a glass plate.

(Molded body)
FIG. 6A is an external perspective view of the molded body 18. FIG. 6B is a diagram showing a state of the molten glass flowing through the molded body 18 when the sheet glass G is formed from the molten glass MG.
The molded body 18 is elongated in the A direction and has a wedge shape with a pentagonal cross section. The molded body 18 includes a supply groove 18a, an upper surface 18b, a side surface 18c, a lower inclined surface 18d, and a lowermost edge line 18e. Since the molten glass MG flows through the supply groove 18a of the molded body 18, the inclined groove 18a is inclined so that the molten glass MG flows obliquely downward from above. For this reason, the distance between the lowest edge ridge line 18e and the upper surface 18b of the molded body 18 decreases as it advances in the A direction. That is, when the lowermost edge line 18e is placed on the horizontal plane, the upper surface 18b is inclined downward in the A direction.

A supply groove 18a through which molten glass flows is provided in the upper part of the molded body 18, and the groove depth of the supply groove 18a becomes shallower in the A direction, and finally the supply groove 18a disappears. Accordingly, the molten glass MG flowing through the supply groove 18a is split into two upper surfaces 18b and 18b provided on both sides of the supply groove 18a from the supply groove 18a in the middle of the groove, as shown in FIG. 6 (b). Overflowing. The molten glass overflowing from the upper surfaces 18b and 18b flows through the lower inclined surfaces 18d and 18d via the side surfaces 18c and 18c, and reaches the lowermost edge line 18e.
At the lowest edge ridge line 18e, the molten glass MG that has flowed in two hands merges to form one plate-like glass. At this time, both ends of the sheet glass G in the width direction are pulled by the transport roller 20 and cooled by the transport roller 20. Thereby, the sheet glass G is conveyed to the slow cooling furnace which is not illustrated as glass which has a fixed thickness and a fixed width. In the slow cooling furnace, the glass sheet G is slowly cooled under the conditions of the atmospheric temperature and the conveyance speed adjusted so as not to cause deformation such as distortion and warpage. Thereafter, the sheet glass G is cut to a certain length by a cutting device (not shown), and the cut sheet glass G is cut into a glass plate of a predetermined size to form a glass plate. The

  Thus, since the molded object 18 shape | molds plate-shaped glass from molten glass MG, the flatness in the upper surface 18b through which the molten glass of the molded object 18 flows, the side surface 18c, and the lower inclined surface 18d is manufactured with high precision as a target. It is important that the thickness of the plate glass G and further the thickness of the glass plate are made uniform. For this reason, it is important to measure the flatness of the upper surface 18b, the side surface 18c, and the lower inclined surface 18d of the molded body 18. In particular, since the upper surface 18b of the molded body 18 is inclined downward in the A direction, it is necessary that the flatness can be accurately measured even in the inclined state. In the system 10 of this embodiment, even when the surface of the measurement object is inclined, it is possible to calculate the flatness with high accuracy. Therefore, in measuring the flatness of the upper surface 18b of the molded body 18, the system 10 The flatness measurement method to be performed is useful. Further, it is difficult to place the descending inclined surface 18d parallel to the horizontal plane, and the inclined measuring surface becomes an inclined measuring surface. Therefore, the flatness measuring method performed by the system 10 is useful.

  The flatness measuring method of the present invention has been described in detail above. However, the present invention is not limited to the above-described embodiment, and various modifications and changes may be made without departing from the spirit of the present invention. It is.

DESCRIPTION OF SYMBOLS 10 System 12 Laser measuring apparatus 12a Laser light source 12b Half mirror 12c Collimating lens 12d Focus lens 12e Pinhole 12f Light receiving element 14 Data processing apparatus 14a CPU
14b Memory 14c Input / output unit 14d Processing control unit 14e Data selection unit 14f Plane calculation unit 14g Distance calculation unit 14h Flatness calculation unit 15 Output device 16 Water tank 16a Liquid surface 18 Molded body 18a Supply groove 18b Upper surface 18c Side surface 18d Lower inclined surface 18e Bottom edge ridgeline

Claims (6)

A flatness measurement method for measuring the flatness of the surface of a measurement object,
Information on the distance in the irradiation direction of the laser light between the surface of the measurement object and the liquid surface as the measurement reference surface at a plurality of positions while the laser measuring device including the laser displacement meter scans the laser light Measuring and capturing
The computer captures the distance information at the plurality of positions measured by the laser displacement meter and the position information of the plurality of positions scanned by the laser displacement meter, and the computer captures the position information at each of the measured positions. When the measurement data representing the distance information as coordinates is represented by points on the coordinate space, all of the points are sandwiched between two parallel planes, and the distance between the two parallel planes is the minimum. And a step of calculating the flatness by searching for a target parallel plane, while changing the inclination of the two parallel planes.   The flatness measurement method according to claim 1, wherein the measurement object is placed in a liquid having transparency, and the liquid level is a liquid level of the liquid.   The flatness measurement method according to claim 1, wherein the computer obtains, as the flatness, a minimum distance that minimizes a distance between the two parallel planes by changing an inclination of the two parallel planes. .   The computer repeatedly performs a process of selecting three data from the plurality of measurement data until all combinations of three data selected from the measurement data are selected, and each time the selection is performed. Further, by obtaining the two parallel planes from the selected three data, the distance between the two parallel planes is determined as the distance between the parallel planes, and all combinations of the three data are selected. The flatness measurement method according to any one of claims 1 to 3, wherein a minimum distance among the obtained distances between the parallel planes is obtained as the flatness.   The said measurement object is a molded object which shape | molds plate-like glass from a molten glass by a downdraw method, The surface of the said molded object is a surface through which a molten glass flows in a downdraw method. The flatness measuring method according to claim 1.   The flatness measurement method according to claim 1, wherein the surface of the measurement object is a surface of a glass plate.

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