JP5081086B2 - Plane glass sheet manufacturing method and glass substrate dividing method - Google Patents

Description

  The present invention relates to a method for cutting glass sheets and other fragile materials, and more particularly to a method for increasing the speed of a laser cutting process that is effective when used in a process for producing a glass substrate for a flat panel display. .

  Conventionally, lasers have been used when dividing glass plates. In Koldratenko's cited reference 1, it is described that a laser beam is used when a so-called blind crack is spread over a glass sheet in order to divide the glass sheet into two. This partial crack extends to the middle of the depth of the glass sheet, and substantially acts as a cutting line. The sheet is then mechanically divided into two along the cut line.

  As one specific form, a small cut or cut is made on one side of the glass sheet, and then a partial crack is formed using laser light, and the cut or cut is spread through the glass sheet. Thereafter, the laser light is brought into contact with the cuts or the cuts in the glass sheet, the laser and the glass sheet are moved relatively, and the laser light is propagated along a desired path of the cut line. It is desirable to direct the flow of fluid coolant to the heated surface portion of the glass downstream from the laser, so that the heated area is quickly cooled after the laser light heats an area of the glass sheet. Thus, by heating the glass sheet with a laser and cooling the glass sheet with an aqueous coolant, the glass sheet is distorted and cracks are spread in the direction in which the laser beam and the coolant have passed.

  According to Kondrenenko, the shape of the beam on the glass sheet is elliptical, and the short axis and long axis of the elliptical shape satisfy the following relationship.

a = 0.2 to 2.0h
b = 1.0-10.0h
Here, a and b are the short axis and long axis of the elliptical spot, respectively, and h is the thickness of the material into which the laser light is cut. According to Kondrenenko, when b is larger than 10.0 h, the accuracy of cutting is reduced. Therefore, with a glass substrate having a thickness of 0.7 mm, according to Kondrenenko, the major axis of the beam spot cannot be 7 mm or more.
International Publication No. 93/2005

  Due to the development of cutting technology using such laser light, some results have been obtained in terms of the quality of the cut surface, and liquid crystal and other flat panel display panels where a very high quality of the cut surface is desired. They are effective means for manufacturing substrates. However, despite considerable effort in the development of the process over the past few years, to date, it is practically sufficient for use in the manufacture of flat panel display (such as LCD) substrates. Cutting speed is not achieved. In fact, the maximum cutting speed reported in the example of the Kondratenko patent is 120 mm / sec, and in most other examples it is much inferior to this mediocre cutting speed.

  Recently, a document published by Jenoptik at a trade exhibition in Munich, Germany on July 19-23, 1995, stated that laser cutting could be performed at a speed of 30-150 mm / sec. Yes. Jenoptik uses the same laser incision process described in the Kondratenko patent.

  In the manufacture of flat panel display substrates, a laser incision process that makes these processes practical makes possible a high incision rate, for example, a speed of at least about 300 mm / sec, even at least 500 mm / sec, and even 1000 mm / sec. It is desirable to implement.

  The present invention relates to a method of cutting a glass sheet (or other fragile material), and an extremely elongated laser beam in a desired path across the glass sheet to induce cracks along the path of the laser beam. (And coolant is optional). The resulting thermal gradient causes a tensile stress in the surface layer of the glass, and if this stress exceeds the tensile strength of the glass, the glass will fall into the area where the blind cracks and the incision line are lowered into the compressed state. Get into. Then, when the laser beam crosses the glass, the crack follows the laser beam. The depth, shape and direction of the crack are determined by the stress distribution, and the power density, size and shape of the beam spot, the relative speed between the beam spot and the material, the nature and characteristics of the coolant supplied to the heating area, It depends on several factors, such as the thermophysical and mechanical properties of the material to be cracked and its thickness. By using a laser beam with an extremely elongated beam spot on the glass and placing this elongated beam spot in the direction of propagation of the desired split line on the glass sheet, laser cutting is faster than using methods according to known techniques It turns out that speed can be achieved.

  Thus, in the present invention, the laser spot has an extremely elongated shape, for example, an elliptical shape. The long axis of the elongated shape is preferably 20 mm or more, more preferably 30 mm or more, and further preferably 40 mm or more.

  It may be desirable for the minor axis of the beam to be so narrow that it does not impair the quality of the cut surface when forming a straight cut surface.

  In the present invention, the laser beam preferably has a non-Gaussian intensity distribution. In one embodiment, the intensity of the laser beam is preferably a two-peak mode, i.e., including one or more levels, such as a laser operating in both TEM01 * and TEM00 modes. In order to cause very local cooling of the surface layer along the cutting line, it is desirable to direct the appropriate coolant flow along the direction of travel of the beam spot to the region of the material.

  According to the present invention, a cutting speed of 300 to 700 mm / sec or more can be achieved in a glass having a thickness of about 0.4 mm to 3.0 mm without impairing the cutting accuracy or the cut surface of the glass.

  The present invention relates to a system for cutting glass sheets along a desired cutting line using laser cutting technology. As shown in FIG. 1, in the glass cutting system of the present invention, the glass sheet 10 has a main upper surface and a main lower surface 11. First, since the glass sheet 10 forms the crack starting point 19 in the end of the glass sheet 10, a cut | notch and a notch | incision are put along the end of a glass sheet. This crack start point 19 is then used to form a crack 20 by moving the laser beam 16 across the glass sheet along the path of the desired cutting line. The laser light effectively heats the glass sheet in a local region along the desired cutting line. The resulting temperature gradient causes a tensile stress in the surface layer of the material, and when this stress exceeds the tensile strength of the material, blind cracks descend into the compressed region of the material and penetrate the material. A water coolant is applied by water jet 22 to increase the stress distribution and thereby promote crack propagation. As the laser beam crosses the glass, the crack follows the path along which the laser beam propagates.

  Since the surface temperature of the glass 10 is directly dependent on the time of exposure to the laser beam, by using an elliptical beam instead of a circular cross section, at the same relative velocity, each point on the glass surface along the cutting line. Heating time can be extended. Thus, at the specified power density of the laser beam 16, the distance from the laser beam spot required to maintain the depth necessary to heat the glass 10 to the leading edge of the cooling spot is the same. For example, the allowable range of the relative moving speed between the laser beam spot and the material increases as the laser beam spot spreads in the moving direction.

  As shown in FIG. 2, in the present invention, the laser spot is extremely elongated, for example, elliptical, and has a long axis of 20 mm or more, more preferably 30 mm or more, and even 40-100 mm or more. . The major axis of the laser beam spot is the propagation direction of the desired cutting line across the glass sheet. For thin glass sheets (1.1 mm or thinner), the optimum length of the long axis of the laser beam spot is related to the desired propagation speed, and the long axis b is the length that travels per second at the desired laser cutting speed. Is preferably greater than 10%. Thus, at a desired laser cutting speed of 500 mm / sec with a 0.7 mm thick glass, the long axis of the laser is preferably at least 50 mm long.

  The crack 20 preferably extends only in the depth direction of the glass sheet 10 (distance d), thereby acting as a cut line. The glass sheet is finally divided into smaller sheets by applying a bending moment to the crack 20. The bending can be accomplished by conventional bending equipment (not shown) and techniques such as those used to cut glass in a process using conventional mechanical surface cutting methods. Since the crack 20 uses a laser cutting technique rather than a mechanical cut, the formation of glass chips that occur during the mechanical cutting process can be minimized as compared to conventional techniques.

  The laser beam used in the glass cutting process must be capable of heating the glass surface to be cut. As a result, it is desirable that the laser radiation has a wavelength that is absorbed by the glass. In order for this to occur, the emitted light is preferably infrared light having a wavelength of 2 μm or more. For example, a CO 2 laser having a wavelength of 9-11 μm, a CO laser having a wavelength of 5-6 μm, and an HF having a wavelength of 2.6-3.0 μm. A beam such as a laser or an erbium YAG laser having a wavelength of about 2.9 μm is desirable. In most of the experiments, a 150-300 watt power CO2 laser was used, but using a higher power laser appears to be more successful.

  Cracks 20 are formed in the glass toward the interface of the heating and cooling regions, which is the region of maximum thermal gradient. The depth, shape, and direction of the crack are determined by the distribution of thermoelastic stress, and are mainly based on the following plurality of factors.

-Beam spot power density, size, shape;
-Relative movement speed of the beam spot and material;
-Thermophysical properties, conditions and quality of supplying coolant to the heating zone;
-Thermophysical and mechanical properties of the material to be cracked, its thickness, surface condition In order to optimize the cutting cycle for different materials, an appropriate relationship between the main parameters and the cutting process variables It is necessary to establish As described in WO 93/20015, referring again to FIG. 2, depending on the size of the beam spot 18 and the distance l from the region through which the cooling water flows to the beam spot, the glass 10 The relative speed V of the traversing beam spot 18 and the depth d of the crack 20 are expressed by the following equations.

V = ka (b + l) / d
Here, V is a relative moving speed between the beam spot and the material, k is a proportional coefficient depending on the thermophysical properties of the material and the power density of the beam, a is the width of the beam spot, and b is the length of the beam spot. , L is the distance from the near end of the beam spot to the front end of the cooling zone, and d is the depth of the blind crack 4.

  The laser operates by lasing produced in a resonator defined by a mirror at each end. The concept of a stable resonator can be most clearly clarified by following the optical path of the light beam through the resonator. The stability threshold is reached when a light beam parallel to the axis of the laser resonator is reflected back and forth between the two mirrors permanently and without loss.

  A resonator that does not reach the stability criterion is called an unstable resonator because the beam deviates from the axis. There are many types of unstable resonators. One simple example is a convex spherical mirror for a plane mirror. Other examples include concave mirrors with different diameters (the reflected light from the large mirror escapes around the edge of the small mirror), pairs of convex mirrors, and the like.

  The two types of resonators have different advantages and different mode patterns. A stable resonator concentrates light along the laser axis and efficiently extracts energy from that region, but energy is not efficiently extracted from the outer peripheral region away from the axis. The resulting beam has an intensity peak at the center and the intensity attenuates Gaussian as it moves away from the axis. This is a standard type used with low gain continuous wave lasers.

  An unstable resonator attempts to spread the light inside the laser resonator over a larger volume. For example, the output beam may have an annular shape having a ring-shaped intensity peak around the axis.

  Laser resonators have two types of different modes: transverse mode and longitudinal mode. A transverse mode exists in the cross-sectional shape of the beam, ie, the intensity pattern. Longitudinal modes correspond to different resonant modes due to laser cavity lengths occurring at different frequencies or wavelengths within the laser gain band. Single transverse mode lasers that oscillate in a single longitudinal mode oscillate at a single frequency, while those that oscillate in two longitudinal modes oscillate simultaneously at two independent wavelengths (usually at close intervals).

  The electromagnetic field “shape” in the laser resonator depends on the curvature of the mirror, the spacing, and the cavity diameter of the discharge tube. Even if the arrangement, spacing, and wavelength of the mirrors change slightly, the “shape” (electromagnetic field) of the laser beam changes greatly. Special terms have been developed to describe the “shape” and the spatial energy distribution of the beam, but here the transverse modes are classified according to the number of local minima appearing in the beam cross section in two directions. The lowest order mode or fundamental mode has an intensity peak at the center and is known as the TEM00 mode. This is a conventionally used laser having a Gaussian intensity distribution as shown in FIG. The mode with one local minimum along one axis and no local minimum along its vertical axis is TEM01 * or TEM10, which are determined by their orientation. An example of the intensity distribution of the TEM01 * mode is illustrated in FIG. 3 (beam intensity I with respect to distance d across the beam). For most laser applications, the TEM00 mode is considered the most desirable. However, it has been found that non-Gaussian mode beams such as TEM01 * mode and TEM10 mode can be used to deliver laser energy more uniformly to the glass surface. As a result, it has been found that a higher laser cutting speed can be achieved with lower power than when the laser has a Gaussian intensity distribution. Furthermore, a wider range of laser power can be used due to its extended operating range of the laser cutting process. This seems to be because the non-Gaussian laser beam can further improve the uniformity of energy distribution throughout the beam.

  The laser beam shown in FIG. 3 is ring-shaped. The power distribution shown in FIG. 3 is a cross section of the power distribution of the ring-shaped laser beam. A non-Gaussian beam in which at least a pair of intensity peaks are located at the outer periphery of the central region having a lower power distribution is desirable in the present invention. Thus, it is desirable that the center of the laser beam has a power intensity lower than the power intensity of at least a plurality of outer peripheral regions of the laser beam. This low power center region may be completely at zero power level, in which case the laser beam has a 100% TEM01 * power distribution. However, the laser beam is in two-peak mode, i.e. one or more modes such as a combination of TEM01 * and TEM00 modes in which the power distribution in the central region simply drops below the power distribution in the outer region as shown in FIG. It may be a combination of levels. When the beam is in the two-peak mode, it is desirable that the beam has a combination of 50% or more in the TEM01 * mode, more preferably 70% or more in the TEM01 * mode, and the rest in the TEM00 mode.

  In a preferred specific embodiment of the invention, a system controller (not shown) such as a digital computer is connected to a system that controls the movement of lasers, glass sheets, and other moving parts on the system. The system controller uses conventional machine control techniques to control the movement of various components of the system. The system controller uses various manufacturing operation programs stored in its memory, each program appropriately moving a laser or glass sheet (and other moving parts if necessary) for a specific size glass sheet. It is desirable to be designed to control.

  The following example demonstrates the method according to the invention.

Example 1
In this example, the operation of a CO2 laser having a Gaussian power distribution is shown.

  Laser 16 was a model 1200 axial two-beam CO2 laser manufactured by PRC Corporation. The beam operated in TEM00 mode and was placed about 2 meters from the glass surface with a spot size of about 12 mm (the diameter of the laser beam at the laser emission point). A pair of cylindrical lenses was placed in the optical path of the laser between the laser and the glass surface to deform the laser spot. As a result, the laser spot where the laser hits the glass was about 45-50 mm in length, and became an elongated oval shape with a width of about 0.1-0.15 cm at the midpoint. The fundamental mode of this laser resonator is TEM00. When this is the only mode that can oscillate in the resonator, the resonating 00 mode laser will propagate with the smallest possible divergence and will be focused to the smallest spot size. In this example, the laser power distribution was Gaussian (operating in TEM00 mode) by utilizing a “planar” optical coupler at the laser front end face with a small internal aperture.

  In order to form the crack starting point 19 in the aluminosilicate glass sheet 10 having a width of about 500 mm × a length of 500 mm × a thickness of about 1.1 mm, an edge of the glass sheet was manually cut. As a result, a small incision line having a length of about 8 mm and a depth of about 0.1 mm was formed at one end of the upper surface of the glass to create a crack start point 19. The glass sheet 10 is placed so that the laser 16 is in contact with the crack start point 19 and the glass sheet 10 is placed in a straight path that traverses the glass sheet with the power and speed described in Table 1 below. I moved it along.

Table 1
Laser speed Peak power (W) Success rate (%)
400mm / sec 120 100
420 mm / sec 120-165 100
465 mm / sec 165-175 100
475 mm / sec 165-179 100
480 mm / sec 168-179 66
500mm / sec 183-188 33
The success rate column represents the best performance achieved in the corresponding power range. A 100% success rate indicates that in the specified power range, there was an operating parameter where laser cutting into the glass sheet was virtually always 100% successful over time.

Example 2
The same method, apparatus and laser as described in Example 1 were used, and the resonator was operated with a higher order mode power distribution. In particular, the laser is in a two-peak mode and consists of a plurality of sub-beams, each of which has an intensity distribution. Since these beams are independent, their net distribution is the algebraic sum of the individual shapes, weighted by the power rate of each mode. As an example, the amount of TEM00 mode can be reduced by changing the curvature of the optical coupler or increasing the diameter of the opening. In this example, the laser power distribution was changed to a mixing ratio of about 60 to 40 TEM01 * mode and TEM00 mode (resulting in a spot size of about 14 mm) to a beam length of about 50-60 mm. This was achieved by replacing the 20 meter radius of curvature concave optical coupler with a “planar” optical coupler, resulting in a larger opening. The laser power and speed varied as described in Table 2.

Table 2
Laser speed Peak power (W) Success rate (%)
300mm / sec 90-145W 100
500mm / sec 155-195W 100
600mm / sec 200W 100
650mm / sec 200-220W 100
700mm / sec 250W 50
When the laser used in Example 1 was converted to a non-Gaussian laser with TEM01 * mode, higher cutting speeds were achieved with lower laser power. An even wider range of laser power was allowed to make a satisfactory cut edge. As can be seen by comparing the results of Example 1 and Example 2, the Gaussian laser was able to achieve 100% breakage (successfully engraved almost all samples) at cutting speeds up to 475 mm / sec. Above these speeds, it was difficult to obtain consistently satisfactory results. However, it can be expected that speeds of 1000 or 2000 mm / sec will be achieved using the method of increasing the beam length of the present invention.

Example 3
In this example, the laser that produces the laser beam is an axial CO2 laser, a model SS / 200/2, manufactured by PRC Corporation, with a 600 W / beam dual beam laser. The beam was about 12 mm spot size in TEM00 mode. The laser was placed about 2 meters from the glass surface. A pair of cylindrical lenses was placed in the path of the laser beam between the laser and the glass surface to change the laser spot. As a result, the laser spot became an elongated ellipse having a length of about 40-50 mm when hitting the glass and a width of about 1-1.5 mm at the midpoint. The laser power distribution was a 60:40 mixture of TEM01 * and TEM00 modes, which was achieved by using a concave optical coupler with a 20 meter radius of curvature at the laser front facet. The laser power was varied between 160-200 W and the laser speed across the glass sheet was about 500 mm / sec.

  The glass sheet 10 is an alumina silicate glass sheet having a width of about 500 mm × a length of 500 mm × a thickness of about 1.1 mm. The glass sheet 10 is a second one orthogonal to the direction of the first laser cutting line three times on one side of the sheet in the first direction. Three laser cuts were made three times on the other side of the sheet in the direction of. This type of incision method doubles the manufacturing work efficiency in the production of LCD substrate glass, where the outermost incision line removes the outer edge of the glass sheet and the intermediate incision line on each side of the sheet is The remainder of the glass is separated in cooperation with the four members used. Using three score lines on each side of the glass sheet resulted in nine intersections where the path of the score line on one side of the sheet intersected the score line on the other side of the sheet.

  To accomplish this, the glass sheet 10 was manually cut on each side along the edge of the glass sheet so that the laser cut line formed three crack start points 19 at the desired location. Thus, three crack start points 19 were formed at one end of the upper surface of the glass in the form of a small incision line having a length of about 1-8 mm and a depth of about 0.1 mm. The crack need not be 4-8 mm, but rather a crack that can be spread by a laser is sufficient to act as a crack starting point. The glass sheet 10 is arranged so that the laser 16 is in contact with one of the crack start points 19, and the path of the laser 16 is along a straight path traversing the glass sheet forming the cut line 20 as shown in FIG. 1. The glass sheet 10 was moved. This process was repeated to form each of the three cut lines 20 on the first side of the glass sheet.

  Thereafter, the glass sheet 10 was turned over to expose the opposite side of the glass sheet 10. Sheet 10 is manually cut along the edge of the glass sheet to form three other crack initiation points 10 and again the path of laser 16 traverses the glass sheet to form three cut lines 20. The glass sheet 10 was moved along the straight path. Three incision lines made on the second side of the sheet were formed orthogonal to the opposite side of the three incision lines formed on the first side of the glass sheet 10 and orthogonal to the path of each of the three incision lines. .

  Thereafter, a bending moment was applied to the cutting line 20 in order to separate the glass sheet 10 along each cutting line 20. The resulting sheets were then turned over and a bending moment was applied to these sheets in the area of each incision line 20, thereby dividing them into smaller sheets. This process was repeated with 100 or more glass sheets, thereby forming 900 or more intersections where the path of the cut line 20 intersected the path of the cut line 20 located on the opposite side of the glass sheet. In all cases, the split edges were consistently of very high quality.

Example 4
In this example, a single CO2 laser 16 was used to remove the portion of the protective plastic layer and split the glass sheet 10 into smaller sheets. The glass sheet was about 400 mm wide × 400 mm long × 1.1 mm thick, and was coated with a protective layer of an LFC-3 mask film produced by Main Tape Corporation. LFC-3 is a polyethylene film material, approximately 0.002 inches thick (approximately 0.05 mm), stored in roll form, and provided with an acrylic adhesive on one side. The film was applied to the glass so that the adhesive was in contact with the glass sheet, and the coated glass was then pressed between a pair of rollers to promote adhesion between the glass and the film.

In this example, the laser 16 was a model 1200 axial flow two beam CO2 laser manufactured by PRC Corporation. The laser beam is the diameter of about 7mm at the exit end of the laser, thus the spot size emitted by the laser is about 38.5 mm ^2, operating at approximately 70 W, the power density of the beam is about 1.82W / mm ² It became. The laser was placed about 2 meters from the protective layer on the glass surface. In order to form a laser spot, a pair of cylindrical lenses was arranged in the laser optical path between the laser and the glass surface. As a result, the laser spot shape on the protective layer was about 33 mm long, and became an elongated elliptical shape with a width of 2 mm in the middle, resulting in a power density of about 1.35 W / mm ² . The glass sheet was placed under the laser 16 at about 250 mm / min. It moved at the speed of. The laser 16 evaporated all of the protective layer in contact with the laser, thereby selectively removing the protective layer, and the width of the striped stripe 14 was about 2 mm wide. There was no residue in the area where the protective layer was removed, and the protective layer residue was completely removed.

  The glass sheet 10 was manually cut to form the crack start point 19 at the end of the glass sheet. A cut was made in the glass in region 14 where the protective layer was selectively removed. As a result, a crack starting point 19 was formed at one end of the upper surface of the glass in the form of a small cut line having a length of about 8 mm and a depth of about 0.1 mm. The glass sheet 10 was placed so that the laser 16 was in contact with the crack start point 19, and the glass sheet 10 was moved so that the path of the laser 16 was along the same path as the first scan of the laser 16. As a result, the laser 16 propagated through the selective removal portion 14 of the protective layer. About 250 mm / min. The glass sheet 10 was moved at a speed of The laser effectively heated the glass in the area of the glass surface where the laser hit. By locally heating by the laser, a crack started from the crack start point 19 and extended along the path traveled by the laser 16 propagated across the glass surface. This crack was about 0.1 mm deep. Manual pressure was applied to the glass sheet to apply a bending moment to the cracks caused by the laser, thereby dividing the glass sheet into two sheets.

The perspective view of the glass cutting method process by this invention Enlarged view of the laser beam spot on the glass surface in the process shown in FIG. Graph showing the desired intensity shape of the laser shown in FIG. 1 and FIG. Graph showing the power distribution of a standard Gaussian laser

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass sheet 11 Glass sheet main surface 16 Laser beam 18 Laser spot 19 Crack starting point 20 Crack 22 Water jet

Claims (11)

Forming a crack starting point on the glass sheet;
To form the cracks crossing the glass sheet using the crack start point, the laser beam having a non-Gaussian components, as engineering Before moving to traverse the glass sheet, and
Dividing the glass sheet into small sheets along the crack by applying a bending moment to the crack ;
A method for producing a flat glass sheet comprising:
An elongated beam spot the laser beam on the glass sheet, manufacturing method of a flat glass sheet in which the beam spot is characterized Rukoto which have a longest dimension of more than 30 mm. The step of forming the crack start point includes a step of making a cut or a cut along one end of the glass sheet in order to form a crack start point at one end of the glass sheet. A method for producing a flat glass sheet. The method for producing a flat glass sheet according to claim 1, wherein the moving step includes a step of traversing the glass sheet from the crack starting point. The moving causes step, with respect to said glass sheet, a manufacturing method of the flat glass sheet of claim 1 to 3 any one of claims, characterized in that it comprises a step of moving the laser beam at a speed of at least 300 mm / sec . The step of moving includes moving the laser beam having a beam spot having a length of 10% or more of a length at which the longest axis moves at a speed of 1 second at a speed of at least 300 mm / sec. The manufacturing method of the flat glass sheet of any one of Claim 1 to 3 characterized by these. The flat glass sheet according to any one of claims 1 to 3 , wherein the longest axis of the laser beam has a length greater than 10% of a distance that the laser beam moves with respect to the glass sheet in one second. Manufacturing method . The thickness of the said glass sheet is 0.4 mm to 3.0 mm, The manufacturing method of the flat glass sheet of any one of Claim 1 to 6 characterized by the above-mentioned. In a method for dividing a glass substrate having a thickness of 0.4 mm to 3.0 mm used for a flat panel display,
The method provides a flat glass sheet having a thickness of 0.4 mm to 3.0 mm;
Forming a crack starting point on the glass sheet;
A laser beam having a non-Gaussian component is moved across the glass sheet at a speed of at least 300 mm / sec to form a crack across the glass sheet using the crack initiation point . Moving process ;
Dividing the glass sheet into small sheets along the crack by applying a bending moment to the crack ; and
Having
The laser beam has an elongated beam spot on the glass sheet;
The beam spot has a longest dimension of 30 mm or more;
A method of dividing a glass substrate, wherein cracks crossing the glass sheet are sufficiently formed by the moving step. 9. The step of forming the crack start point includes a step of making a cut or a cut along one end of the glass sheet to form a crack start point at one end of the glass sheet. A method for dividing a glass substrate. The glass substrate dividing method according to claim 8, wherein the moving step includes a step of causing the laser beam to cross the glass sheet from the crack starting point. Said moving step from claim 8 longest axis, characterized in that it comprises a step of moving the laser beam having a length of about 10% or more of the length of a beam spot which moves in one second by the speed The method for dividing a glass substrate according to any one of 10 .

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