Method for cutting a thin glass layer

Abstract

Method for cutting a glass layer having a first surface a second surface. The method includes moving a first laser beam, which is generated by a pulsed laser, along a cutting line, where material modifications are produced in the interior of the glass layer between the first surface and the second surface; moving a second laser beam along the cutting line where the glass layer is heated by the laser radiation; and cooling the glass layer along the cutting line, where the glass layer breaks along the cutting line.

Claims

1. A method for cutting a glass layer with a thickness less than or equal to 0.3 mm, having a first surface and a second surface, comprising: a) moving a first laser beam, generated by a pulsed laser with a pulse length less than 1 ps and a repetition rate from 20 kHz to 500 kHz, having a wavelength of 300 nm to 500 nm and a power of 20 W to 100 W, along a cutting line, wherein a focus of the first laser beam is positioned between the first surface and the second surface, and wherein material modifications including local regions of increased density developing through self-focusing of a radiation of the first laser beam are produced in the interior of the glass layer between the first surface and the second surface; b) moving a second laser beam along the cutting line, wherein the glass layer is heated by the laser radiation; and c) cooling the glass layer along the cutting line, wherein the glass layer breaks along the cutting line, wherein each material modification is generated by a pulse train, in which a time interval between consecutive pulses becomes larger and is from 50 times up to 5000 times the pulse length.

2. The method according to claim 1, wherein along the cutting line, a distance between adjacent material modifications is less than 100 m.

3. The method according to claim 2, wherein the distance between adjacent material modifications is less than 20 m.

4. The method according to claim 1, wherein a pulse energy of the consecutive pulses decreases and wherein the pulse energy is from 4 J to 500 J.

5. The method according to claim 1, wherein the second laser beam has a wavelength of 1 m to 20 m.

6. The method according to claim 1, wherein the second laser beam is generated by a laser in a continuous wave mode.

7. The method according to claim 1, wherein the second laser beam has a power of 30 W to 1 kW.

8. The method according to claim 1, wherein the cooling of the glass layer is done by impacting with a gaseous and/or liquid coolant along the cutting line, by means of a nozzle.

9. A method comprising: cutting a glass layer with a thickness less than or equal to 0.3 mm by performing a method according to claim 1 to provide a cut glass layer, and positioning the cut glass layer in an arrangement selected from the group consisting of a thin-film solar cell, an active glazing with electrically switchable properties, an electrochromic element, a polymer dispersed liquid crystal (PDLC) element, an electroluminescent element, an organic light-emitting diode (OLED), a suspended particle device (SPD) element, and a component of a vehicle glazing.

Description

(1) The invention is explained in detail with reference to drawings and exemplary embodiments. The drawings are schematic representations and not to scale. The drawings in no way restrict the invention. They depict:

(2) FIG. 1 a perspective view of a glass layer during the method according to the invention,

(3) FIG. 2 a cross-section through the glass layer along the cutting line L,

(4) FIG. 3 an exemplary embodiment of the method according to the invention with reference to a flowchart.

(5) FIG. 1 and FIG. 2 show in each case a detail of a schematic representation of the method according to the invention for cutting a glass layer 1, for example, an ultrathin glass layer with a thickness of 80 m.

(6) First, a first laser beam 2, which is focused on the interior of the glass layer 1 between the two glass surfaces I, II, is moved along a desired cutting line L. The first laser beam 2 is generated by a pulsed laser with a pulse length of, for example, 500 fs, a pulse frequency of, for example, 25 kHz, a power of, for example, 50 W, and a wavelength of, for example, 355 nm. A suitable laser is, for example, a Q-switched solid-state laser, in particular a diode-pumped solid-state laser. The glass layer 1 is nearly transparent at the wavelength of the first laser beam. However, the highly concentrated laser radiation results in internal modifications of the glass material, so-called filaments 5. These modifications 5 are limited to the interior of the glass; the glass surfaces I, II are not changed or damaged. The material modifications 5 are lined up along the cutting line L. The local weakening of the glass layer associated with the material modifications 5 defines the cutting line L as the predetermined breaking point. Each filament is produced by a pulse train of the first laser beam 2. The pulse trains separated from one another include, in each case, for example, 5 pulses and are produced with a so-called burst generator.

(7) Subsequently, a second laser beam 3 is moved along the cutting line L. The second laser beam 3 is, for example, the beam of a CO.sub.2 laser in the continuous wave mode with a wavelength of 10.6 m and a power of 50 W. The second laser beam 3 is focused on the glass surface by means of cylindrical optics (not shown) with an elongated beam profile. On the glass surface, the profile has, for example, a length of 30 mm and a width of 500 m. The beam profile is aligned along the cutting line L, i.e., the long axis of the beam profile lies on the cutting line L. The second laser beam 3 is effectively absorbed by the glass layer 1, thus heating the glass layer along the cutting line L.

(8) Behind the second laser beam 3, a nozzle 4 is moved along the cutting line L. The laser beam 3 and the nozzle 4 move at the same speed. The glass layer is impacted by means of the nozzle 4 with coolant, for example, cooled CO.sub.2. The rapid cooling of the heated glass layer results in thermal tensions, resulting in breakage of the glass layer 1 along the cutting line L.

(9) The arrows shown in the figure indicate the direction of motion. The speed v.sub.1 for the movement of the first laser beam 2 is, for example, 125 mm/s. The second laser beam 3 and the nozzle 4 are moved in direct succession with the speed v.sub.2 of, for example, 250 mm/s.

(10) The cutting line L is schematically depicted as a straight line. In reality, however, very complex shapes can be realised. For example, smaller panes with virtually any shape can be cut from a large-area glass layer. As has been demonstrated, the breaking of the glass layer occurs automatically due to the thermal tensions. Active breaking by exertion of pressure can, consequently, be dispensed with. Thus, small radii of curvature can be realised and material waste can be reduced. In addition, the method yields smooth cut edges without bothersome damage such as microcracks. These are major advantages of the present invention.

(11) FIG. 3 depicts an exemplary embodiment of the method according to the invention for cutting glass layers.

EXAMPLE 1

(12) 50-m-thick glass layers were subjected to various cutting methods and the separation effect compared. The process conditions and the observations in the majority of cases are summarised in Table 1.

(13) TABLE-US-00001 TABLE 1 Producing the pre- Separating the determined breaking line glass layer Observation A Filaments by Heating by Deformation Q-switched CO.sub.2-laser of the glass diode-pumped (CW, 50 W, solid-state laser (355 nm, 10.6 m) 500 fs, 25 kHz, 25 W) B Filaments by Heating by Clean separation Q-switched CO.sub.2-laser of the glass diode-pumped (CW, 50 W, solid-state laser (355 nm, 10.6 m) + 500 fs, 25 kHz, 25 W) Cooling with CO2

(14) Only the Method B according to the invention resulted in reliable separation of the glass layer. Without the cooling (Method A), the thermal loading of the ultrathin glass layer is obviously so high that deformations occur.

EXAMPLE 2

(15) Shapes having radii of curvature of 1.5 mm were cut from 50-m-thick glass layers using various cutting methods. The processing conditions and the observations in the majority of cases are summarised in Table 2.

(16) TABLE-US-00002 TABLE 2 Producing the pre- Separating the determined breaking line glass layer Observation A Filaments by mechanical Damaging of the Q-switched pressure glass layer diode-pumped to be cut out solid-state laser (355 nm, 500 fs, 25 kHz, 25 W) B Filaments by Heating by Clean separation Q-switched CO.sub.2-laser of the glass layer diode-pumped (CW, 50 W, to be cut out solid-state laser (355 nm, 10.6 m) + 500 fs, 25 kHz, 25 W) Cooling with CO.sub.2

(17) By means of the Method B according to the invention, it was possible to cut out the complex shapes unproblematically. In the case of the Comparative Method A with mechanical pressure, the complex shapes were damaged during separation.

LIST OF REFERENCE CHARACTERS

(18) (1) glass layer (2) first laser beam (for producing the predetermined breaking line along L) (3) second laser beam (for severing the glass layer 1) (4) nozzle for cooling the glass layer 1 (5) filament/local internal material modification v.sub.1 moving speed of the first laser beam 2 v.sub.2 moving speed of the second laser beam 3 L cutting line I first surface of the glass layer 1 II second surface of the glass layer 1