# US 10,501,359 B2 · Method for controlling the thickness of a substrate

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- Number: US 10,501,359 B2
- Document ID: US10501359B2
- Status: Granted
- Kind: B2
- Application number: 15/424,611
- Filed: 2017-02-03
- Published: 2017-08-10
- Granted: 2019-12-10
- Earliest claimed: 2016-02-04
- Assignees: Schott AG
- Applicants: Schott AG
- Inventors: Frank Buellesfeld; Ulrich Lange; Georg Haselhorst
- Web page: https://patentgrep.com/patent/US10501359B2

## CPC

- C03B 23/037: by drawing
- C03B 17/064: {by the overflow downdraw fusion process; Isopipes therefor}
- C03B 17/067: {combined with thermal conditioning of the sheets}
- C03B 29/08: Glass sheets
- C03B 29/16: Glass sheets
- C03B 2205/40: Monitoring or regulating the draw tension or draw rate
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

A method for controlling the thickness of a glass ribbon and an article produced thereby are provided. The method includes: providing a glass ribbon by drawing from a melt or redrawing from a preform; predefining a nominal thickness of the glass ribbon; determining the thickness of the glass ribbon over its entire net width; determining at least one deviation of the thickness of the glass ribbon from the predefined nominal thickness; identifying the area of the thickness deviation in the glass ribbon; and heating the area of the at least one thickness deviation in the glass ribbon using a laser, so that the glass ribbon attains the predefined thickness.

## Claims

### Claim 1

A method for controlling thickness of a glass ribbon, comprising:
providing a glass ribbon by drawing from a melt or redrawing from a preform with a drawing rate (vGB) and an average thickness (D) in a net portion;
predefining a nominal thickness of the glass ribbon;
determining a thickness of the glass ribbon over an entire net width (B);
determining at least one deviation of the thickness from the nominal thickness;
identifying an area on the glass ribbon of the at least one deviation; and
heating the area using a laser beam to cause the area to attain the nominal thickness, wherein the heating further comprises controlling at least a power of the laser beam, a duration of irradiation of a laser beam, or a wavelength of the laser beam as a function of the thickness,
wherein the laser is equipped with a scanning head configured to scan the entire net width of the glass ribbon; and
wherein the following relationship applies between the entire net width (B), the drawing rate (vGB), a beam diameter (D) of the laser beam, a scanning rate of a laser (vLas), and a correction factor k:
2·k·vGB·B<D·vLas, and
wherein the correction factor k is at least equal to or greater than 1 and the entire net width and the beam diameter are given in meters and the drawing rate and the scanning rate of the laser are given in meters per second.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein the correction factor k is at least equal to or greater than 10.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein, prior to the heating, the area has a viscosity in a range between 104 and 109 dPa·s, and wherein areas of excessive thickness are subjected to a greater laser power than areas of appropriate or undersized thickness.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the scanning head has an optical lever or a length of the optical path between the glass ribbon and a scanner mirror of between at least 1.8 m and at most 5.0 m.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein the laser power is at most 3000 W.

### Claim 6 (depends on 1)

The method as claimed in claim 1, wherein the laser beam acts on a deformation zone of the glass ribbon.

### Claim 7 (depends on 1)

The method as claimed in claim 1, wherein the step of providing the glass ribbon by drawing or redrawing comprises drawing or redrawing by virtue of a weight of the glass ribbon.

### Claim 8 (depends on 1)

The method as claimed in claim 1, wherein the laser is a CO2 laser.

### Claim 9 (depends on 1)

The method as claimed in claim 1, wherein the step of determining of the thickness comprises measuring selected from the group consisting of an interference measurement, a chromatic confocal measurement, a white light topography measurement, a white light interferometry measurement, and combinations thereof.

### Claim 10 (depends on 1)

The method as claimed in claim 1, further comprising directing the laser beam by a galvanometer scanner and/or a polygon mirror wheel.