JP2019043799A - End face treatment method of glass substrate and end face treatment device of glass substrate - Google Patents

Abstract

To reduce a residual stress of a glass substrate which is integrated with a material such as a resin having low heat resistance, and to reduce a residual stress for a glass substrate, before breakage, which is usually broken by a high residual stress within several tens minutes.SOLUTION: An end face treatment method of a glass substrate G treats an end face 20 after the glass substrate G has been cut, and includes: a melt chamfering step of melt chamfering the end face 20 of the glass substrate G; and a residual stress reduction step of heating an end face neighbor portion 21 of the glass substrate G and reducing a residual stress.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for processing an end surface of a glass substrate and an end surface processing apparatus for a glass substrate.

In order to cut a glass substrate into product dimensions, a scribe line is formed on the glass substrate by a wheel, and the glass substrate is bent along the scribe line by bending the glass substrate (see, for example, Patent Document 1) ).
However, residual force remains in the scribe line due to the force applied by the wheel blade and the stress applied at break up. Therefore, a crack tends to occur naturally in the horizontal direction on the surface of the glass substrate, and with time, the crack further grows due to moisture or the like.

Moreover, the technique which improves the intensity | strength of the end surface of a glass substrate is known by irradiating a laser beam to the end surface (edge) of a glass substrate, and performing fusion | melting chamfering (for example, refer patent document 2). In this melting and chamfering, fine cracks on the substrate edge disappear and the end face strength is improved.
However, in this method, residual stress occurs in the vicinity of the fusion zone. And, the residual stress increases the possibility of the substrate being broken. Specifically, there is a high possibility that the internal defects will grow with time or failure due to subsequent flaws, and depending on the magnitude of the residual stress, the failure may occur within tens of minutes.

JP-A-6-144875 Patent No. 5245819 gazette

In consideration of the above, conventionally, a method has been developed to reduce the residual stress on the end face of the glass substrate. For example, in the method for reducing residual stress of a glass substrate, slow cooling is performed after the temperature rise. Specifically, first, the entire glass substrate is uniformly heated to a temperature equal to or higher than the glass transition temperature, then held for a certain period of time, and finally gradually cooled to room temperature. In general, the process of heating, holding, and slow cooling requires several hours or more.
This method has an advantage that residual stress on the end face of the glass substrate can be almost completely removed. In addition, there is an advantage that a plurality of glass substrates can be processed simultaneously in a furnace.

However, since the whole substrate is heated to the glass transition point or more, it can not be applied to a glass product integrated with a low heat resistant material such as, for example, a resin. FIG. 46 shows a glass product in which the resin materials P1 and P2 are integrally formed on the glass substrate G.
In addition, since one residual stress reduction process takes several hours or more, residual stress can not be reduced immediately after the occurrence of residual stress. Therefore, it is difficult to apply to a glass substrate having a high probability of breakage occurring within tens of minutes due to high residual stress.

A first object of the present invention is to reduce residual stress of a glass substrate integrated with a low heat resistant material such as resin.
A second object of the present invention is to be able to reduce residual stress before breakage occurs, even for glass substrates whose breakage usually occurs within a few tens of minutes due to high residual stress.

  Below, a plurality of modes are explained as a means to solve a subject. These aspects can be arbitrarily combined as needed.

The end surface processing method of a glass substrate according to the first aspect of the present invention is a method of processing an end surface of a glass substrate after cutting, and has the following steps.
溶 融 Melt chamfering step to melt and chamfer the end face of the glass substrate.
残留 Residual stress reduction step that reduces the residual stress by heating the area near the end face of the glass substrate.
In this method, since the vicinity of the end face of the glass substrate is heated, it is possible to reduce the residual stress on the end face of the glass substrate integrated with a low heat resistant material such as resin. This is because the entire glass substrate is not heated, so that the resin and the like are not easily affected by heat.
In addition, in this method, residual stress is reduced in the heating area by heating the glass substrate for about 1 picosecond to 100 seconds, so breakage is generally caused even in the glass substrate which causes breakage within several tens of minutes. It is possible to reduce the residual stress before the occurrence of
The “end face vicinity portion” is a portion corresponding to the end face and the vicinity thereof.
"The portion near the end face is heated" means that there is a portion which is not heated at the center side from the portion near the end face.
“Reducing residual stress” means suppressing the temporal growth of internal defects and reducing residual stress to such an extent that a glass substrate to which no external force is applied does not crack within a predetermined time.
The residual stress reducing means is, for example, an apparatus capable of partial heating, and a heat source for performing partial heating is, for example, a laser or various heaters.
The residual stress reduction step may be started in the middle of the melting and chamfering step, and then both steps may be performed simultaneously. Alternatively, the residual stress reduction step may be started after the fusion chamfering step is completed.

  The residual stress reducing step may include a laser beam scanning step of scanning a laser beam along the end face in the vicinity of the end face of the glass substrate.

  The residual stress reducing step may have a laser beam irradiation step of irradiating each of a plurality of locations in the vicinity of the end face of the glass substrate with a laser beam.

  In the laser beam irradiation step, a plurality of laser beams may be irradiated to a plurality of locations simultaneously or repeatedly in a short time.

The end surface processing apparatus for a glass substrate according to another aspect of the present invention is an apparatus for processing an end surface of the glass substrate after cutting, and includes a melting and chamfering apparatus and a residual stress reducing apparatus.
The melting and chamfering apparatus melts and bevels the end face of the glass substrate.
The residual stress reduction device heats a portion near the end face of the glass substrate to reduce the residual stress.
In this apparatus, since the vicinity of the end face of the glass substrate is heated, it is possible to reduce the residual stress in the vicinity of the end face of the glass substrate integrated with a low heat resistant material such as resin. This is because the entire glass substrate is not heated, so that the resin and the like are not easily affected by heat.
Further, in this apparatus, residual stress is reduced in the heating area by heating the glass substrate for about 1 picosecond to 100 seconds, so that breakage is usually caused even within a few tens of minutes. It is possible to reduce the residual stress before the occurrence of

  The residual stress reduction device may scan laser light along the end face in a portion near the end face of the glass substrate.

  The residual stress reducing device may irradiate laser light to each of a plurality of places in the vicinity of the end face of the glass substrate.

  The residual stress reduction device may irradiate a plurality of laser beams to a plurality of locations simultaneously or repeatedly in a short time.

According to the present invention, it is possible to reduce the residual stress of a glass substrate integrated with a low heat resistant material such as a resin.
Furthermore, according to the present invention, it is possible to reduce residual stress before breakage occurs even for a glass substrate whose breakage usually occurs within several tens of minutes due to high residual stress. By heating the glass substrate for about 1 picosecond to 100 seconds, residual stress is reduced in the heating region.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram of the laser irradiation apparatus of 1st Embodiment of this invention. The schematic diagram of a glass substrate which shows movement of a laser spot. Cross section photograph of the fusion bevelled glass substrate. The graph which shows the change of the retardation toward the center side from the end face of the glass substrate by which the fusion | melting chamfer was carried out. The typical top view which shows the part to which the residual stress of the glass substrate is high. Typical sectional drawing which shows the part to which the residual stress of the glass substrate is high. The schematic diagram of a glass substrate which shows movement of a laser spot. The graph for comparing the change of the retardation toward the center side from the end face of the glass substrate by which the fusion | melting chamfer was carried out before and behind a residual-stress reduction process. The graph for comparing the change of the retardation toward the center side from the end face of the glass substrate by which the fusion | melting chamfer was carried out before and behind a residual-stress reduction process. The graph for comparing the change of the retardation toward the center side from the end face of the glass substrate by which the fusion | melting chamfer was carried out before and behind a residual-stress reduction process. The simulation result which shows temperature distribution in case scanning speeds differ in residual stress reduction processing. The simulation result which shows temperature distribution in case scanning speeds differ in residual stress reduction processing. The typical top view which shows the variation of the shape of laser spot S at the time of enforcing 2nd Embodiment. The typical top view which shows the variation of the shape of laser spot S at the time of enforcing 2nd Embodiment. The typical top view which shows the variation of the shape of laser spot S at the time of enforcing 2nd Embodiment. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of the glass substrate which shows movement of the laser spot of 2nd Embodiment. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. Typical top view which shows an example of the order of a heating position. Typical top view which shows an example of the order of a heating position. The schematic diagram of the laser irradiation apparatus of the modification of 2nd Embodiment. The schematic diagram of the glass substrate which shows movement of the laser spot of 3rd Embodiment. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The schematic diagram of a glass substrate which shows movement of a laser spot. The typical top view which shows the variation of the space | interval of a heating area | region. The typical top view which shows the variation of the space | interval of a heating area | region. The schematic diagram which shows the branch of the laser spot using a diffractive optical element or a transmissive | pervious space light modulator. The schematic diagram which shows a branch of the laser spot using a reflection type spatial light modulator. The schematic diagram which shows the beam formation by a cylindrical lens. The schematic diagram which shows beam formation by a galvano scanner. The schematic diagram which shows beam formation by a polygon mirror. The typical top view which shows the positional relationship of a shielding board and a glass substrate. The typical front view which shows the positional relationship of a shielding board and a glass substrate. The typical top view of the laser irradiation apparatus of the 2nd modification of 3rd Embodiment. The typical front view of a laser irradiation apparatus. The schematic diagram which shows formation of the beam of 3 points | pieces using a galvano scanner. FIG. 7 is a graph showing the change in laser pulse and beam angle with respect to time. The typical top view of the conventional glassware united with the low heat-resistant material.

1. First Embodiment (1) Laser Irradiation Apparatus FIG. 1 shows the entire configuration of a laser irradiation apparatus 1 according to an embodiment of the present invention. FIG. 1 is a schematic view of a laser irradiation apparatus according to a first embodiment of the present invention.
The laser irradiation apparatus 1 has a function of melting and chamfering the end face of the glass substrate G, and a function of heating a portion near the end face of the glass substrate G to reduce residual stress in the vicinity of the end face.

The glass substrate G includes those made of only glass and those in which other members such as resin are combined with glass. Typical examples of the type of glass include soda glass and alkali-free glass used for displays and instrument panels, but the type is not limited thereto. The thickness of the glass is specifically 3 mm or less, for example, in the range of 0.004 to 3 mm, preferably in the range of 0.2 to 0.4 mm.
The end face vicinity portion means an end face and a portion in the vicinity thereof, and includes the end face near portion of the outer peripheral edge and the end face near portion of the edge of the hole.

The laser irradiation device 1 includes a laser device 3. The laser device 3 has a laser oscillator 15 for irradiating the glass substrate G with a laser beam, and a laser control unit 17. The laser control unit 17 can control the drive of the laser oscillator 15 and the laser power.
The laser device 3 has a transmission optical system 5 for transmitting a laser beam to the mechanical drive system side described later. The transmission optical system 5 includes, for example, a condenser lens 19, a plurality of mirrors (not shown), a prism (not shown) and the like.
The laser irradiation apparatus 1 has a drive mechanism 11 that changes the size of the spot of the laser beam by moving the position of the lens in the optical axis direction.

  The laser irradiation apparatus 1 has a processing table 7 on which a glass substrate G is placed. The processing table 7 is moved by the table drive unit 13. The table drive unit 13 has a moving device (not shown) for moving the processing table 7 in the horizontal direction with respect to the head (not shown). The moving device is a known mechanism having a guide rail, a motor and the like.

The laser irradiation apparatus 1 includes a control unit 9. The control unit 9 has a processor (for example, CPU), a storage device (for example, ROM, RAM, HDD, SSD, etc.), and various interfaces (for example, A / D converter, D / A converter, communication interface, etc.) It is a computer system. The control unit 9 performs various control operations by executing a program stored in the storage unit (corresponding to a part or all of the storage area of the storage device).
The control unit 9 may be configured by a single processor, but may be configured by a plurality of independent processors for each control.

The control unit 9 can control the laser control unit 17. The controller 9 can control the drive mechanism 11. The control unit 9 can control the table drive unit 13.
Although not shown, a sensor for detecting the size, shape and position of the glass substrate G, a sensor and a switch for detecting the state of each device, and an information input device are connected to the control unit 9.

(2) Melting and Chamfering Operation The operation of melting and chamfering the end face of the glass substrate G will be described with reference to FIGS. FIG. 2 is a schematic view of a glass substrate showing movement of a laser spot. FIG. 3 is a cross-sectional photograph of a melt-chamfered glass substrate. FIG. 4 is a graph showing a change in retardation from the end face of the melt-chamfered glass substrate toward the center.

First, the glass substrate G is set at a predetermined position on the processing table 7.
Next, as shown in FIG. 2, a laser beam is applied to the glass substrate G toward the end face vicinity portion 21 of the glass substrate G, and the laser spot S is scanned along the end face 20 of the glass substrate G. At this time, the laser spot S is set so as to be, for example, 10 μm to 150 μm away from the end face 20 of the glass substrate G toward the inner side (central side) of the substrate.

  The irradiation and scanning of the laser spot S as described above heat the end face vicinity portion 21 of the glass substrate G. In particular, by irradiating laser light of mid-infrared light, the laser light is absorbed while being transmitted to the inside of the glass substrate G. Therefore, the end surface 20 of the glass substrate G is relatively uniformly heated not only on the front surface side that is the irradiation surface of the laser light but also over the entire inside and back surface side of the glass substrate G. Therefore, the end surface 20 of the glass substrate G is melted so that the central portion of the substrate thickness bulges outward, and as a result, as shown in FIG. 3, the end surface 20 is chamfered.

However, the method of melting and chamfering is not particularly limited. As another example, the laser light is irradiated from both or one of the front surface and the back surface of the glass substrate G, and the laser light is irradiated from the direction orthogonal to the end surface 20 of the glass substrate G. It may be melted and chamfered. Laser light of far infrared light may be emitted.
As a result of the above, as shown in FIG. 4, the retardation (nm) is high in the vicinity of the end face of the glass substrate G (for example, in the area of end face 20 to 200 μm). The retardation is a phase difference generated in the light transmitted through the object, and is a value proportional to the stress acting in the object. The fact that the retardation of an object to which no external force is applied is high means that the residual stress is high.

(3) Residual Stress Reduction Process A residual stress reduction process for heating a portion near the end face of the glass substrate G will be described with reference to FIGS. 5 to 7. FIG. 5 is a schematic plan view showing a portion where the residual stress of the glass substrate is high. FIG. 6 is a schematic cross-sectional view showing a portion where the residual stress of the glass substrate is high. FIG. 7 is a schematic view of a glass substrate showing movement of a laser spot.

As shown in FIG. 7, a laser beam is applied to a portion 21 near the end face of the glass substrate G with respect to the glass substrate G on the processing table 7, and the laser spot S is along the portion 21 near the end face of the glass substrate G Scan. The end face vicinity portion 21 here corresponds to a residual stress generation region Z (hatched region) in which a residual stress is generated by the melting and chamfering.
At this time, the laser spot S is set smaller than the glass substrate G, for example, to a size of about 4 μm to 20 mm. Thereby, the end face vicinity part 21 of the glass substrate G is heated by the laser spot S.

The inventors of the present invention have found that in the residual stress reduction process, it is necessary to suppress the high temperature region to a narrow range in the direction along the end face 20, and reached the present invention. The grounds will be described later. That is, the scanning speed of the laser spot S is set low to heat the glass substrate G to a temperature above the glass transition point. As a result, the high temperature region does not spread in the direction along the end face 20, and the effect of reducing the residual stress is enhanced. Conversely, setting the scan rate fast increases the power required to heat to temperatures above the glass transition temperature. When the high power laser spot S is scanned at a high speed, the high temperature area spreads in the direction along the end face 20, and the effect of reducing the residual stress is reduced.
The scanning speed may be 20 mm / s or less, preferably 10 mm / s or less, and more preferably less than 5 mm / s.

As a result of the above, the portion 21 in the vicinity of the end face of the glass substrate G (that is, the residual stress generation region Z) is heated to the glass transition point or more, and as a result, the residual stress is reduced.
In this method, since the end face vicinity portion 21 of the glass substrate G is heated (that is, the entire glass substrate G is not heated), the end face vicinity portion of the glass substrate G integrated with a low heat resistant material such as resin. The residual stress of 21 can be reduced. It is because it is hard to produce the influence of a heat | fever to resin etc. Furthermore, if the area of the residual stress generation area Z is not extremely wide, the residual stress reduction process can be completed within a few tens of minutes, and for high glass substrates, breakage usually occurs within a few tens of minutes. Even in this case, the residual stress can be reduced before the failure occurs.

The type (wavelength) of the laser is not particularly limited.
The required laser output is an output capable of heating the glass substrate G to the glass transition point or more. For this reason, a higher laser output is required when using a laser with a low light absorptivity for glass.
Moreover, as a heat source, it is not limited to a laser, For example, an infrared heater and a contact type heater may be sufficient.
In addition, when the temperature of the heating part of glass substrate G is a glass transition point grade, a deformation | transformation of a heating part is hardly confirmed. When the temperature of the heating unit is higher, the heating unit melts and the shape changes. The higher the laser output, the lower the viscosity of the heating part, and the greater the deformation in a short time. According to the present invention, even when the laser output is high and the shape of the glass substrate G is deformed, the residual stress is reduced. However, when the present invention is applied to a product having a restriction on the allowable deformation of the glass substrate G, the upper limit of the laser output is set so that the viscosity of the glass substrate G is reduced and the deformation does not exceed the allowable value. Should be set.

The heat input direction to the glass substrate G is not particularly limited. The heat may be input from the front surface of the glass substrate G, may be input from the back surface, or may be input from the end surface 20.
In the above embodiment, the residual stress reduction processing is performed after the melting and chamfering is finished, but the melting and chamfering processing and the residual stress reduction processing may be performed in parallel on one glass substrate G. Specifically, by using two laser beams, the residual stress reduction process is started in the middle of the melting and chamfering operation, and thereafter both processes are performed simultaneously. In that case, the overall processing time is shortened.
In order to use a plurality of laser beams, a plurality of laser oscillators may be prepared, or a laser beam may be branched from one laser oscillator.

(4) Experimental Example An experimental example of residual stress reduction processing by laser scanning will be described with reference to FIGS. FIGS. 8 to 10 are graphs for comparing the change in retardation from the end face to the center side of the melt-chamfered glass substrate (alkali glass with a thickness of 200 μm) before and after the residual stress reduction treatment. .
The residual stress reduction process was possible with either a mid-infrared laser (Er fiber laser) or a far-infrared laser (CO ₂ laser). The specifications of the Er fiber laser are a wavelength of 2.8 μm, a maximum output of 10 W, an optical absorptivity of about 30%, and a substantial heat input of up to 3 W. The specifications of the CO ₂ laser are a wavelength of 10.6 μm, a maximum output of 250 W, an optical absorptivity of about 80%, and a substantial heat input of up to 200 W.

(4-1) First Experimental Example In the first heating (melting and chamfering) of FIG. 8, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.

In the second heating (residual stress reduction processing) of FIG. 8, an Er fiber laser was used, and the substrate subjected to the melting and chamfering under the above conditions was heated under the conditions of spot sizes 2 mm, 4 W and 0.2 mm / s.
As apparent from FIG. 8, the maximum value of the residual stress is significantly reduced.

(4-2) Second Experimental Example In the first heating (melting and chamfering) of FIG. 9, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.
In the second heating (residual stress reduction processing) of FIG. 9, an Er fiber laser was used, and the substrate subjected to the fusion chamfering under the above conditions was heated under the conditions of spot sizes 1 mm, 3.5 W and 1 mm / s. As apparent from FIG. 9, the maximum value of the residual stress is reduced.

  In any of the experimental examples shown in FIG. 8 and FIG. 9, the residue of the molten and chamfered glass substrate is likely to be spontaneously broken within several minutes to several days before the residual stress reduction treatment, while the residual is high. After the stress reduction treatment, it did not break even after one month. In the residual stress reduction process, the power density of the laser beam is adjusted so that the glass is not melted and the shape is not changed. That is, the residual stress was reduced and the probability of the glass substrate being broken spontaneously was reduced without changing the shape of the melt-chamfered glass substrate end face.

(4-3) Third Experimental Example In the first heating (melting and chamfering) of FIG. 10, an Er fiber laser was used, and the spot size was 200 μm, 5 W, and 3 mm / s.
In the second heating (residual stress reduction processing) of FIG. 10, an Er fiber laser is used, and the substrate subjected to the melting and chamfering under the above conditions is subjected to the spot size of 0.4 mm, 4 mm / s, and the laser power of 4 to 6 W Heated. In the case of the laser power of 4 W, no change was observed in the residual stress generated in the first heating (melting chamfer). This is because the laser output was low and the temperature of the glass substrate G did not exceed the glass transition point. At a laser power of 5.5 W, the maximum residual stress was slightly reduced. In addition, the residual stress greatly increased in a part of the region where the residual stress was low in the first heating (melting chamfer). In the case of a laser output of 6 W, as a result of the high laser output, the glass substrate G was melted and deformed. Even if the laser output is set high until the glass substrate melts and deforms, the residual stress generated in the first heating (melting chamfer) is hardly reduced, and the region in which the residual stress is low in the first heating (melting chamfer) The residual stress increased significantly in part of the
As seen from FIG. 10, in the present experimental example, the residual stress reduction effect was low even if the laser output was adjusted.

(4-4) Discussion As described above, the scanning speed of the second heating (residual stress reduction processing) is 0.2 mm / s in the first experimental example and 1 mm / s in the second experimental example. Both gave good results. However, as can be seen from the comparison of graphs, the higher the scanning speed, the lower the residual stress reduction effect. In the third experimental example, as a result of setting the scanning speed to 4 mm / s more quickly, the residual stress was hardly reduced. As mentioned above, in the case of the laser scanning method of this embodiment, it is preferable that a scanning speed is slow. Specifically, the scanning speed may be 20 mm / s or less, preferably 10 mm / s or less, and more preferably less than 5 mm / s.

The present inventors have found based on experiments and temperature simulation of the glass substrate that in the residual stress reduction processing, it is necessary to suppress the high temperature region to a narrow range in the direction along the end face 20. It came to the invention. This basis is described, for example, by FIG. 11 and FIG. FIG. 11 and FIG. 12 are simulation results showing temperature distribution when the scanning speed is different in the residual stress reduction process.
FIG. 11 shows the case where the scanning speed of the laser spot S is as slow as 0.2 mm / s and the residual stress reduction effect is high. Since the scanning speed is set to a low speed, the high temperature part (for example, a region exceeding 300 ° C.) does not extend along the end face.
On the other hand, FIG. 12 shows a case where the scanning speed is as fast as 20 mm / s and the residual stress reducing effect is low. However, the laser output is set high so as to be heated to the same temperature as in FIG. It can be seen that the high temperature portion is longer along the end face as compared with FIG.
These results are one of the grounds showing that the residual stress reducing effect is reduced when the high temperature part is elongated along the end face.

  Furthermore, the second experimental example according to the second embodiment described later also shows the ground for achieving the present invention. In the second experimental example, instead of scanning the laser spot S along the end face vicinity 21, the residual stress in the heated area is reduced by heating one point in the end face vicinity 21 for a predetermined time. . FIG. 13, FIG. 14 and FIG. 15 are schematic plan views showing variations of the shape of the laser spot S when carrying out the second embodiment.

In FIG. 13, a circular laser spot S100 and an elliptical laser spot S101 long in the direction orthogonal to the end face 20 are shown. In FIG. 14, elliptical laser spots S 102 and S 103 long along the end face 20 are shown. In FIG. 15, a long laser spot S104 is shown along the end face 20 covering the entire end face 20. When the laser spots S100, S101, S102, and S103 were used, the residual stress in the heating area was reduced by adjusting the laser output and the predetermined time for heating. However, the residual stress reduction effect was higher in the order of S100 ≒ S101>S102> S103. When the laser spot S104 was used, the residual stress was not reduced even if the laser output and the predetermined time for heating were adjusted.
In view of the simulation results and the experimental results described above, the inventors have found that in the residual stress reduction process, it is necessary to suppress the high temperature region to a narrow range in the direction along the end face 20. The present invention has been achieved.

(5) First Modification In the first embodiment, the single beam scanning process for reducing the residual stress on one side of the glass substrate G has been described. However, a plurality of beams for irradiating laser light to a plurality of portions near the end face of the glass substrate The residual stress of a plurality of sides may be simultaneously reduced by simultaneous scanning.
Such an embodiment will be described as a first modification with reference to FIGS. 16 to 18. 16 to 18 are schematic views of a glass substrate showing movement of a laser spot.

As shown in FIG. 16, portions near the end faces 21 that are the four sides of the glass substrate G are the residual stress generation regions Z.
As shown in FIG. 17, four laser spots S scan each of four sides.
Thereby, as shown in FIG. 18, the residual stress of the glass substrate G is reduced. In this case, the processing time is shorter than single beam scanning processing. The number of laser spots may be two, three, five or more.

(6) Second Modified Example In the first embodiment, the glass substrate G is a quadrangle and has a plurality of straight sides, but the present invention can be applied to a glass substrate G having a side such as a curved line.
Such an embodiment will be described as a second modification with reference to FIGS. 19 to 21 are schematic views of a glass substrate showing movement of a laser spot.

As shown in FIG. 19, the glass substrate G is circular, and a portion 21 in the vicinity of the end face which is the entire outer peripheral edge is a residual stress generation region Z.
As shown in FIG. 20, four laser spots S scan the four points of the outer circumferential edge in the circumferential direction, respectively. As a modification, the glass substrate G may be rotated.
Thereby, as shown in FIG. 21, the residual stress of the glass substrate G is reduced.
The number of laser spots may be two, three, five or more. The same method can be applied to the case where the portion 21 near the end face of the edge of the hole of the glass substrate G in which the circular hole is formed is the residual stress generation region Z.

2. Second Embodiment (1) Basic Principle In the first embodiment, the laser beam is scanned on the end face as the residual stress reduction process, but the laser beam irradiation method is not limited to this.
Another irradiation method of the laser beam will be described as a second embodiment with reference to FIGS. 22 to 25 are schematic views of the glass substrate showing the movement of the laser spot of the second embodiment. The basic configuration and basic operation of the laser irradiation apparatus are the same as in the first embodiment.

In FIG. 22, the laser spot S <b> 1 is irradiated to one point of the end face vicinity portion 21.
In FIG. 23, the laser spot S <b> 2 is irradiated to another point at a different position of the end face vicinity portion 21.
In FIG. 24, the laser spot S <b> 3 is irradiated to another one of different positions of the end face vicinity portion 21.
In FIG. 25, the laser spot S <b> 4 is irradiated to another one of different positions of the end face vicinity portion 21.

When the laser spot is irradiated to a point on the residual stress generation area Z for a predetermined time and heated to a temperature above the glass transition point, the residual stress is reduced in that area. Therefore, as is apparent from FIGS. 22 to 25, by sequentially heating one point for a predetermined time, the laser spots S1 to S4 are irradiated to the adjacent positions continuously in the end face direction, and as a result, as a result The entire area near the end face 21 is irradiated.
However, the number of laser spots, the position, the order of irradiation, and the ratio occupied in the end face vicinity portion 21 are not limited to this embodiment.

In this embodiment, the residual stress generation area Z is brought to a temperature higher than the glass transition temperature by repeating heating one point for a predetermined time and heating the one point for a predetermined time while shifting the position to the vicinity of the end face. Reduce the residual stress of the entire part 21.
In this embodiment, the laser spot S is finally irradiated to the entire end face vicinity portion 21 to reduce the residual stress of the entire end face vicinity portion 21. However, in the case where the residual stress is reduced only in a partial region of the end surface vicinity portion 21, the laser spot S may be irradiated only to a specific region of the end surface vicinity portion 21. It may be irradiated to only about half of the whole area.

The predetermined time for heating depends on the temperature of the heating zone during heating. That is, the higher the heating power, the higher the temperature of the heating area, and the shorter the residual stress is reduced. The higher the heating power, the shorter the predetermined time for heating, and the shorter the tact time.
The predetermined time for heating is preferably, for example, about 1 picosecond to about 100 seconds. The minimum predetermined time is 1 picosecond known as the minimum of the time required for structural relaxation of the glass (relaxation time). When the temperature of the heating zone is lower, the relaxation time is longer. When the temperature of the heating zone is around the glass transition temperature, it is preferable to set the predetermined time for heating to about 100 seconds which is the relaxation time.
In order to extremely shorten the predetermined time for heating, it is necessary to heat the glass substrate G to a high temperature in a short time, and since the required output is greatly increased, practically, the merit of shortening the tact time and the output increase The heating conditions are determined in consideration of the cost increase due to

  When the laser spot S is circular, for example, the diameter is preferably 4 μm to 20 mm. In the second embodiment, as the diameter of the laser spot S is larger, the processing area per heating is wider, and the time required to reduce the residual stress of the predetermined area is shortened. As shown in FIGS. 13 and 14, the laser spot S may be elliptical. However, as the width of the laser spot S in the direction along the end face 20 is longer than the width in the direction intersecting the end face 20 of the laser spot S, the residual stress reduction effect is reduced. The width of the laser spot S in the direction along the end face 20 is preferably 10 times or less of the width in the direction intersecting the end face 20 of the laser spot S.

The laser output needs to be a value that can heat up to the glass transition point or more. This is appropriately set according to the size of the laser spot, the laser wavelength, the type of glass, and the plate thickness. In addition, when the temperature of a heating part is high, a heating part fuse | melts and a shape changes. According to the present invention, even when the laser output is high and the shape of the glass substrate G is deformed, the residual stress is reduced. However, when the present invention is applied to a product having a restriction on the allowable deformation of the glass substrate G, the upper limit of the laser output is set so that the viscosity of the glass substrate G is reduced and the deformation does not exceed the allowable value. Should be set.
An example of the condition of heating for a predetermined time for an alkali-free glass having a thickness of 200 μm will be described. It is 3 W and 20 s using a CO ₂ laser (wavelength 10.6 μm) with a spot size of 4 mm. It may be 4W, 4s conditions. It may be 6W, 2s conditions.
Moreover, as a heat source, it is not limited to a laser, For example, an infrared heater and a contact type heater may be sufficient.

(2) Shifted irradiation method of laser spot When the heating method of the above predetermined time is performed while shifting the position, heating for the first time, shifting for the second heating, shifting for the third heating, ... heating for a predetermined time sequentially It will be. At this time, in order to shorten the tact time, it is necessary to shorten the time interval between the heating operations. However, for example, in the order of heating positions shown in FIG. 26, the area adjacent to the immediately preceding heating area is the next heating area. In this case, for example, the second heating needs to wait until the temperature of the first heating unit decreases. The reason is that, for example, when the second heating area is combined with the first heating area, the above-mentioned “when the high temperature part becomes long along the end face in the case of heating the end face vicinity portion of the glass substrate G” It is because it corresponds.

(2-1) First Method In the case of performing the above-described shifted irradiation, there is a heating position sequence devising method as a first method for shortening the time interval between heating operations. In this method, specifically, as shown in FIG. 27, the area adjacent to the immediately preceding heating area is skipped, and the separated area is made the next heating area.

(2-2) Second Method As a second method for shortening the time interval between heating operations, there is a substrate cooling method. FIG. 28 shows a substrate cooling device 35 for cooling the substrate with jet air from the front side or the back side of the glass substrate G. FIG. 28 is a schematic view of a laser irradiation apparatus of a modification of the second embodiment.
In this case, the second heating is performed after cooling the first heating area by air cooling or the like. Thereby, even when heating is performed in the order shown in FIG. 26, the time interval can be shortened.

  The reason why the time interval can be shortened as described above is that since the next laser beam is irradiated after the laser beam is irradiated and the heated portion is cooled, the next laser beam is near the previously heated portion. Even if it irradiates, the area | region which becomes high temperature has not spread in the direction along an end surface by cooling. That is, in this case, this corresponds to the case where the high temperature part is suppressed narrow along the end face in the case of heating the end face vicinity part of the glass substrate G described above.

The cooling medium for cooling is not particularly limited.
The substrate cooling device may be realized by making the table on which the glass is placed a water cooling table.
The substrate cooling mechanism may be mounted on the laser irradiation apparatus 1.

3. Third Embodiment The predetermined time heating method according to the second embodiment employs a single-point heating method in which laser irradiation is performed for each point, but laser irradiation may be performed simultaneously for multiple points.
Such an example will be described as a third embodiment with reference to FIGS. In this multipoint simultaneous irradiation method, the substantial processing speed is increased. 29 to 32 are schematic views of a glass substrate showing movement of a laser spot of the third embodiment.

In FIG. 29, two laser spots S1 are irradiated to the end face vicinity portion 21.
FIG. 30 shows a state in which the residual stress is reduced in the end face vicinity portion 21 by the operation of FIG.
In FIG. 31, two laser spots S2 are applied to the end face vicinity portion 21. At this time, the two laser spots S2 are irradiated at positions different from the two previous laser spots S1, that is, shifted. The two laser spots S2 correspond to the remaining residual stress generation area Z.
FIG. 32 shows a state in which the residual stress is reduced in the end face vicinity portion 21 by the operation of FIG.

In the multipoint simultaneous heating method, when the number of heating regions is n points, an output of n times is required as compared with the single-point heating method of the second embodiment. Moreover, in the shielding system mentioned later, according to the area of a shielding part, a still higher output is needed.
The heating conditions per point are the same as in the second embodiment.

The distance between the heating areas is preferably 0.5 or more times the width of one heating area. If the spacing between the heating areas is too narrow, then several heating areas will be connected, which is equivalent to irradiating one long laser spot along the end face 20. That is, the residual stress reduction effect is reduced corresponding to the above-mentioned “when the high temperature part in the case of heating the end face vicinity portion of the glass substrate G becomes long along the end face”. A variation of the shape and spacing of the heating area is shown using FIG. 33 and FIG. FIG.33 and FIG.34 is a typical top view which shows the variation of the shape and space | interval of a heating area | region.
Three circular laser spots S105 are shown in FIG. The laser spot S105 has the same shape as the laser spot S100 of FIG. 13 and has a high residual stress reduction effect. Further, the distance between the laser spots S105 is set to be approximately the same as the width of the laser spots S105.
In FIG. 34, a long elliptical three-point laser spot S106 is shown in the direction crossing the end face 20. The laser spot S106 has the same shape as the laser spot S101 of FIG. 13 and has a high residual stress reduction effect. Further, the distance between the laser spots S106 is set to be approximately the same as the width of the laser spots S106.
There are many combinations of the shape of the laser spot and the spacing other than the above.

  The processing speed of the residual stress reduction process varies with the number of heating areas. For example, in the case of the width 8 mm of the heating area, simultaneous heating at 10 points, the heating time 1 s, and the residual stress reduction width 4 mm per heating area, the treatment speed for one irradiation is 4 mm × 10/1 s = 40 mm / s.

A method of performing multipoint simultaneous heating using the light branching element will be described using FIGS. 35 and 36. FIG. FIG. 35 is a schematic view showing a branch of a laser spot using a diffractive optical element or a transmissive spatial light modulator. FIG. 36 is a schematic view showing a branch of a laser spot using a reflective spatial light modulator.
In FIG. 35, a diffractive optical element (DOE) 31 or a transmissive spatial light modulator (SLM) 31 is shown.
In FIG. 36, a reflective spatial light modulator (SLM) 33 is shown. Also, two mirrors 34 are shown.

  When performing the multipoint simultaneous heating method while shifting the position as shown in FIG. 29 to FIG. 32, the first heating, the second heating, the second heating, the third heating,. To be done. At this time, in order to shorten the tact time, it is necessary to shorten the time interval between the heating operations. However, for example, when any of the plurality of second heating regions is adjacent to any of the plurality of first heating regions, the temperature of the first heating portion decreases in the second heating. You need to wait until you The reason is that, for example, when the second heating area is combined with the first heating area, the above-mentioned “when the high temperature part becomes long along the end face in the case of heating the end face vicinity portion of the glass substrate G” It is because it corresponds.

As a first method of shortening the time interval between the heating operations, in the above case, the time interval is set by devising the heating position order so that the second heating area is positioned away from the first heating area. It can be shortened.
There is a substrate cooling method as a second method for shortening the time interval between heating operations. In this method, as shown in FIG. 28 of the second embodiment, a substrate cooling device 35 is used which cools the substrate from the front side or the back side of the glass substrate G by jet air. In this case, the second heating is performed after the first heating area is cooled by air cooling or the like. Thus, for example, even when the second heating area is adjacent to the first heating area, the time interval can be shortened.

The reason why the time interval can be shortened as described above is that since the next laser beam is irradiated after the laser beam is irradiated and the heated portion is cooled, the next laser beam is near the previously heated portion. Even if the light is irradiated, the high temperature area does not spread in the direction along the end face by cooling. That is, in this case, this corresponds to the above-mentioned "case where the high temperature part is suppressed narrow along the end face in the case of heating the end face vicinity part of the glass substrate G".
The cooling may be always performed or may be performed after the laser light irradiation.
As in the second embodiment, the configuration of the cooling device, the cooling means, and the arrangement position are not particularly limited.

(1) First Modification A method of performing multipoint simultaneous heating by a shielding method will be described with reference to FIGS. FIG. 37 is a schematic view showing beam formation by a cylindrical lens. FIG. 38 is a schematic view showing beam formation by a galvano scanner. FIG. 39 is a schematic view showing beam formation by a polygon mirror. FIG. 40 is a schematic plan view showing the positional relationship between the shielding plate and the glass substrate. FIG. 41 is a schematic front view showing the positional relationship between the shielding plate and the glass substrate.
An elongated beam along the end face 20 is formed by the cylindrical lens 41 (FIG. 37), the galvano scanner 43 (FIG. 38), the polygon mirror 45 (FIG. 39) or the like.

Then, as shown in FIGS. 40 and 41, a plurality of laser spots S are formed by partially shielding the laser beam B using a shielding plate 47. The shielding plate 47 has a plurality of shielding portions 47a arranged with a gap in the end face direction.
The shielding plate 47 needs to reflect or absorb the laser light. In the case of absorption, it is necessary to have heat resistance. If the laser light is absorbed but the heat resistance is not sufficient, it is necessary to provide a forced cooling mechanism for the shield plate.
In addition, the mechanism (not shown) which moves the shielding board 47 along the end surface vicinity part 21 of the glass substrate G may be provided. In this case, the positions of the plurality of laser spots S can be changed, and by repeating this, the laser spot S can be irradiated on the entire end face vicinity portion 21.

(2) Second Modified Example A method of performing multipoint simultaneous heating by scanning a laser beam one pulse at a time will be described with reference to FIGS. FIG. 42 is a schematic plan view of a laser irradiation apparatus of a second modified example of the third embodiment. FIG. 43 is a schematic front view of a laser irradiation apparatus. FIG. 44 is a schematic view showing formation of three laser spots using the galvano scanner 43. As shown in FIG. FIG. 45 is a graph showing changes in laser pulse and ray angle with respect to time.
As shown in FIGS. 42 and 43, the laser irradiation apparatus 1A includes a laser oscillator 15, a beam expander 49, a condenser lens 19, and a galvano scanner 43. Then, the laser irradiation apparatus 1A controls the irradiation position of each pulse of the laser light by using the galvano scanner 43, and simultaneously irradiates the laser light to a plurality of places at the same time to create a state where multiple points are heated simultaneously. .

In the example of FIG. 44, by changing the beam angle of the laser beam by 1 degree by the galvano scanner 43, the position of the laser spot moves 10 mm on the sample surface. When the light beam angle is changed in synchronization with the laser pulse oscillating at 500 Hz as shown in FIG. 45, the laser light reciprocates once in a 20 mm area with a period of 12 milliseconds, and each of the three laser spots has one period ( The laser light is emitted only for 2 milliseconds in 12 milliseconds. Further, the region between the three laser spots is not irradiated with the laser beam. In this case, since the scanning cycle of the laser light is sufficiently fast, if the operation is repeated for a predetermined time (for example, one second), the three points are heated simultaneously for a predetermined time.
In the second modification, a substrate cooling device 35 is provided as shown in FIG. However, the substrate cooling device may not be necessary.

4. Other Embodiments Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. In particular, the embodiments and modifications described herein may be arbitrarily combined as needed.

  The present invention can be widely applied to a method of processing an end surface of a glass substrate and an end surface processing apparatus of a glass substrate.

DESCRIPTION OF SYMBOLS 1: Laser irradiation apparatus 3: Laser apparatus 5: Transmission optical system 7: Processing table 9: Control part 11: Drive mechanism 13: Table drive part 15: Laser oscillator 17: Laser control part 19: Condensing lens 20: End face 21: End face vicinity portion 35: Substrate cooling device 41: Cylindrical lens 43: Galvano scanner 45: Polygon mirror 47: Shielding plate G: Glass substrate S: Laser spot Z: Residual stress generation area

Claims (8)

A method of processing an end face of a glass substrate after cutting,
A melting and chamfering step of melting and chamfering the end face of the glass substrate;
A residual stress reducing step of heating a portion near the end face of the glass substrate to reduce residual stress;
The edge processing method of the glass substrate provided with.   The method for processing an end face of a glass substrate according to claim 1, wherein the residual stress reducing step includes a laser light scanning step of scanning a laser beam along the end face in the vicinity of the end face of the glass substrate.   The end surface processing method of the glass substrate according to claim 1, wherein the residual stress reducing step includes a laser light irradiation step of irradiating each of a plurality of locations in the vicinity of the end surface of the glass substrate with a laser beam.   The said laser beam irradiation step is an end surface processing method of the glass substrate of Claim 3 which irradiates repeatedly several laser beams simultaneously or in a short time to these several places. An apparatus for processing an end face of a glass substrate after cutting,
A melting and chamfering apparatus for melting and chamfering the end face of the glass substrate;
A residual stress reducing device that heats a portion near the end face of the glass substrate to reduce residual stress;
Edge processing apparatus for glass substrate provided with   The said residual stress reduction apparatus is an end surface processing apparatus of the glass substrate of Claim 5 which scans a laser beam along the said end surface in the end surface vicinity part of the said glass substrate.   The end surface processing apparatus for glass substrate according to claim 5, wherein the residual stress reducing device irradiates laser light to each of a plurality of locations in the vicinity of the end surface of the glass substrate.   The said residual-stress reduction apparatus is an end surface processing apparatus of the glass substrate of Claim 7 which irradiates repeatedly several laser beams simultaneously or in a short time to these several places.

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