US-12624941-B2 - Roller gap measurement system using light and roller gap measurement method using same

US12624941B2US 12624941 B2US12624941 B2US 12624941B2US-12624941-B2

Abstract

In a roller gap measurement system and a roller gap measurement method using the roller gap measurement system, the roller gap measurement system includes a light source, a refractive part, a sensor part and an image processing part. The light source is configured to provide an incident light toward the gap between first and second rollers. The refractive part is configured to receive a complex light passing through the gap between the first and second rollers, and configured to refract the complex light. The sensor part is configured to receive the refracted light and configured to image a complex pattern. The image processing part is configured to obtain a gap information between the first and second rollers, based on the imaged complex pattern.

Inventors

Dongwoo Kang
Hong Ki YOO
Jin Su Choi
Hyunchang KIM
Seung-Hyun Lee
Kyung-rok Kim
JaeYoung Kim

Assignees

KOREA INSTITUTE OF MACHINERY & MATERIALS
KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY

Dates

Publication Date: 20260512
Application Date: 20230511
Priority Date: 20220512

Claims (18)

1 . A roller gap measurement system configured for measuring a gap between a pair of first and second rollers, the system comprising: a light source configured to provide an incident light toward the gap between the first and second rollers; a refractive part configured to receive a light passing through the gap between the first and second rollers, and configured to refract the light passing through the gap; a sensor part configured to receive the refracted light and configured to image a pattern; and a processor configured to obtain a gap information between the first and second rollers, based on the imaged pattern, wherein the processor is configured to obtain the gap information based on the features of a pattern due to a gap, considering parameters affecting the imaged pattern except for the gap.
2 . The system of claim 1 , wherein the light source is configured to provide a monochromatic laser.
3 . The system of claim 1 , wherein the incident light provided from the light source is diffracted, transmitted, reflected or scattered with passing through the gap between the first and second rollers.
4 . The system of claim 1 , wherein the pattern imaged in the sensor part is a Fraunhofer diffraction pattern.
5 . The system of claim 1 , wherein the sensor part is located spaced apart from the refractive part by a focal length of the refractive part.
6 . The system of claim 1 , wherein the processor is configured to: extract the features of an interference pattern via a frequency analysis on the imaged pattern, extract the features based on an intensity ratio between a central portion of the imaged pattern and a side portion of the imaged pattern on the imaged pattern, or extract the features based on a sum of intensity on the imaged pattern.
7 . The system of claim 1 , wherein an enlarged light generated by enlarging the incident light is provided when the gap between the first and second rollers is larger than a size of the light source.
8 . The system of claim 1 , further comprising: a scanner disposed between the light source and the first and second rollers, and configured to scan the incident light and to provide a scan light.
9 . The system of claim 8 , wherein the scanner is configured to provide the scan light in which the incident light is scanned along a direction perpendicular to an advancing direction of the incident light, wherein an information on the difference between a single slit model and an actual gap between the first and second rollers is obtained according as the scan light is provided.
10 . The system of claim 9 , wherein the scanner comprises a pair of first and second lenses, each of which is a convex lens, wherein the incident light passes through the first and second lenses to be a scan light.
11 . The system of claim 1 , wherein the processor is configured to: extract the features of the pattern from the imaged pattern; receive parameters affecting the pattern, except for the gap; obtain the features of the pattern due to the gap from the extracted pattern, considering an effect by the parameters; and obtain the gap information, based on the obtained pattern features.
12 . The system of claim 11 , wherein the gap information obtained in the processor is an absolute value information or a relative value information on a size of the gap.
13 . The system of claim 11 , wherein the parameters except for the gap are pre-known values which are uniformly maintained without being changed.
14 . The system of claim 13 , wherein the effect of the parameters except for the gap on the extracted pattern is pre-analyzed and stored, wherein the processor is configured to obtain the features of the pattern due to the gap, considering the pre-analyzed and stored effect.
15 . The system of claim 13 , wherein the parameters comprise at least one of an alignment error between the first and second rollers, a radius of each of the first and second rollers, a deformation error and a surface roughness.
16 . A roller gap measurement method comprising: providing an incident light toward a gap between first and second rollers from a light source; receiving and refracting a light passing through the gap between the first and second rollers; receiving the refracted light and imaging a pattern; and obtaining a gap information between the first and second rollers based on the imaged pattern, wherein the obtaining the gap information comprises obtaining the gap information based on the features of a pattern due to a gap, considering parameters affecting the imaged pattern except for the gap.
17 . The method of claim 16 , further comprising: providing a scan light to the gap between the first and second rollers, wherein the incident light is scanned along a direction perpendicular to an advancing direction of the incident light to be the scan light.
18 . The method of claim 16 , further comprising: providing an enlarged light to the gap between the first and second rollers, wherein the incident light is enlarged to be the enlarged light.

Description

BACKGROUND 1. Field of Disclosure The present disclosure of invention relates to a roller gap measurement system and a roller gap measurement method using the roller gap measurement system, and more specifically the present disclosure of invention relates to a roller gap measurement system using a light and a roller gap measurement method using the roller gap measurement system, in which the roller gap in a roll-to-roll equipment is measured in a non-contact manner using a complex interference pattern generated when the light passes through the gap between rollers. 2. Description of Related Technology Generally, in rollers used in a roll-to-roll processing equipment, it is important to maintain a constant gap between the rollers in order to maintain a constant thickness of a transported workpiece. Thus, technology to accurately measure the gap between the rollers is required. Regarding the technologies to measure the gap between the rollers, Japanese laid-open patent No. 2009-265054 disclosed the technology to measure the gap between the rollers using a dial gauge. In addition, Japanese laid-open patent No. 2006-058090 disclosed the technology of contact type gap measurement in which an expandable measuring unit is inserted into a gap between the rollers to measure the gap. However, recently, as the demand for the roll-to-roll processing for relatively thin workpieces increases, the gap between the rollers is also narrowing. Thus, the demand for the technology for measuring the narrowing gap accurately is more increasing. In addition, as the gap narrows, it is difficult to apply conventional contact measurement technologies or measurement technologies using a separate measurement unit. Then, the development of new measurement technologies is required. Related prior arts are Japanese laid-open patent No. 2009-265054 and Japanese laid-open patent No. 2006-058090. SUMMARY The present invention is developed to solve the above-mentioned problems of the related arts. The present invention provides a roller gap measurement system using a light, capable of measuring not only relatively narrow gaps but also gaps in a central portion of a roller accurately, by measuring a roller gap in a roll-to-roll equipment in a non-contact manner using a complex interference pattern generated when the light passes through the gap between the rollers. In addition, the present invention also provides a roller gap measurement method using the roller gap measurement system. According to an example embodiment, the roller gap measurement system is configured for measuring a gap between a pair of first and second rollers. The system includes a light source, a refractive part, a sensor part and an image processing part. The light source is configured to provide an incident light toward the gap between the first and second rollers. The refractive part is configured to receive a complex light passing through the gap between the first and second rollers, and configured to refract the complex light. The sensor part is configured to receive the refracted light and configured to image a complex pattern. The image processing part is configured to obtain a gap information between the first and second rollers, based on the imaged complex pattern. In an example, the light source may be configured to provide a monochromatic laser. In an example, the incident light provided from the light source may be diffracted, transmitted, reflected or scattered with passing through the gap between the first and second rollers, and may be formed as the complex light. In an example, the sensor part may be located spaced apart from the refractive part by a focal length of the refractive part. In an example, the image processing part may include a feature extracting part configured to extract features of a pattern from the imaged complex pattern, a parameter input part configured to receive parameters affecting the complex pattern, except for the gap, an analysis part configured to obtain the features of the pattern due to the gap from the extracted pattern, considering an effect by the parameters, and a decision part configured to obtain the gap information, based on the obtained pattern features. In an example, the feature extracting part may be configured to extract the features of an interference pattern via a frequency analysis on the imaged complex pattern, configured to extract the features based on an intensity ratio between a central portion of the imaged complex pattern and a side portion of the imaged complex pattern on the imaged complex pattern, or configured to extract the features based on a sum of intensity on the imaged complex pattern. In an example, the parameters except for the gap may be pre-known values which are uniformly maintained without being changed. In an example, the effect of the parameters except for the gap on the extracted pattern may be pre-analyzed and stored. The analysis part may be configured to obtain the features of the patt