Precision control of web material having micro-replicated lens array

Patent metadata

Field	Value
Publication number	US-9977154-B2
Application number	US-201113583887-A
Country	US
Kind code	B2
Filing date	Mar 30, 2011
Priority date	Apr 1, 2010
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

A manufacturing system includes a sensing system that provides high-resolution feedback for web guiding and tension control. The system may be especially useful for web material that is manufactured to include micro-replicated structures with micron size scale. A micro-replication station forms a pattern of micro-replicated lenses on a web material. The sensing system illuminates a measurement area on the web material and detects an angular distribution of light exiting a set of the micro-replicated lenses within the first measurement area. A control system that adjusts at least one process control parameter of the transport system based on the detected angular distribution.

First claim

The invention claimed is:

1. A method of manufacturing a patterned web material, the method comprising:
conveying web material by a transport system through a first micro-replication station;
forming a first pattern of micro-replicated lenses on the web material with the first micro-replication station;
illuminating a set of the micro-replicated lenses by directing light from a first light source through the first pattern of micro-replicated lenses on the web material so as to exit from the micro-replicated lenses, the exiting light comprising a plurality of light angles;
simultaneously directly detecting from the plurality of light angles a plurality of light intensities of an angular distribution of the light directed through and exiting from the micro-replicated lenses of the web material, the simultaneous direct detection taking place by passing the light directed through and exiting from the micro-replicated lenses through a multi-element lens, using optical properties of the multi-element lens to produce a Fourier transform of the angular distribution of the light entering the multi-element lens, and recording the Fourier transform of the angular distribution of the light entering the multi-element lens using an array sensor positioned at a focal length of the multi-element lens;
analyzing the plurality of directly detected light intensities of the angular distribution of the light directed through and exiting from the first pattern of micro-replicated lenses; and
determining an alignment error of the web material based on the analysis of the plurality of directly detected light intensities.

2. The method of claim 1 , further comprising adjusting at least one process control parameter of the transport system based on the determined alignment error.

3. The method of claim 2 , wherein the adjusting of the at least one process control parameter comprises adjusting a cross-web position of the web material as the web material is conveyed to the first micro-replication station.

4. The method of claim 2 , wherein the adjusting of the at least one process control parameter comprises adjusting a down-web position of the web material as the web material is conveyed to the first micro-replication station.

5. The method of claim 2 , wherein the adjusting of the at least one process control parameter comprises adjusting both a cross-web position and a down-web position of the web material as the web material is conveyed to the first micro-replication station.

6. The method of claim 2 , wherein the adjusting of the at least one process control parameter comprises adjusting a tension of the web material as the web material is conveyed to the first micro-replication station.

7. The method of claim 2 , further comprising displaying the adjusted process control parameter to an operator as a recommended adjustment.

8. The method of claim 1 , further comprising recording the alignment error in a database.

9. The method of claim 1 , wherein the alignment error exceeds a threshold, further comprising marking the web material upon the alignment error exceeding the threshold.

10. The method of claim 1 , further comprising:
forming a second pattern of micro-replicated features on the web material with a second micro-replication station,
wherein the first pattern of micro-replicated lenses is formed with the first micro-replication station to repeat on a first surface of the web material in a cross-web direction, and
wherein the second pattern of micro-replicated features is formed with the second micro-replication station to repeat on an opposing surface of the web material opposite from the first pattern of micro-replicated lenses.

11. The method of claim 10 , wherein illuminating the set of the micro-replicated lenses by directing the light from the first light source through the first pattern of the micro-replicated lenses on the web material further comprises:
illuminating the set of the micro-replicated features within a measurement area on the opposing surface to direct the light from the first light source through the set of the micro-replicated features and through the set of the micro-replicated lenses on the first surface of the web material.

12. The method of claim 11 , wherein the set of the micro-replicated features comprise micro-replicated prisms.

13. The method of claim 12 , wherein the alignment error of the web material represents an error from an expected alignment between the set of micro-replicated lenses and the set of micro-replicated prisms within the measurement area.

14. The method of claim 10 , wherein illuminating the set of the micro-replicated lenses by directing the light from the first light source through the first pattern of micro-replicated lenses on the web material further comprises:
illuminating a set of the micro-replicated features within a first measurement area on the opposing surface with the first light source to direct the light through the set of the micro-replicated features and through the set of the micro-replicated lenses on the first surface of the web material.

15. The method of claim 10 , wherein illuminating the set of the micro-replicated lenses by directing the light from the first light source through the first pattern of the micro-replicated lenses on the web material further comprises:
illuminating a set of the micro-replicated features within a first measurement area on the opposing surface with the first light source and with a second light source to direct light from the first and second light sources through the set of the micro-replicated features within the first measurement area on the opposing surface and through the set of the micro-replicated lenses on the first surface of the web material,
wherein the simultaneously directly detecting from a plurality of light angles a plurality of light intensities of an angular distribution of the light from the first light source directed through and exiting from the set of the micro-replicated lenses on the first surface of the web material further comprises simultaneously directly detecting from a plurality of light angles a plurality of light intensities of an angular distribution of the light from the second light source directed through and exiting from the set of the micro-replicated lenses on the first surface of the web material, and
wherein the alignment error is determined as a first measurement area alignment error based on a comparison of the simultaneously directly detected plurality of light intensities of the angular distribution of the light from the first light source that is directed through and exits from the set of micro-replicated lenses with the simultaneously directly detected plurality of light intensities of the angular distribution of the light from the second light source that is directed through and exits from the set of micro-replicated lenses.

16. The method of claim 15 , wherein the second pattern of micro-replicated features comprises a set of micro-replicated prisms within the first measurement area, and further wherein the alignment error associated with the first measurement area represents an error from an expected alignment between the set of micro-replicated lenses and the set of micro-replicated prisms within the first measurement area.

17. The method of claim 15 , wherein the alignment error associated with the first measurement area provides a sub-micron alignment resolution.

18. The method of claim 15 , wherein determining the alignment error further comprises:
constructing a first one-dimensional projection based on the si

Assignees

• Hofeldt David L
• Brott Robert L
• Carlson Daniel H
• Dobbs James N
• Jaworski Andrzej P
• Jerry Glen A
• Strand John T
• Sykora Michael J
• Stensvad Karl K
• 3M Innovative Properties Co

Inventors

• Hofeldt David L
• Brott Robert L
• Carlson Daniel H
• Dobbs James N
• Jaworski Andrzej P
• Jerry Glen A
• Strand John T
• Sykora Michael J
• Stensvad Karl K

Classifications

• B29C59/046

  for layered or coated substantially flat surfaces · CPC title

• B29C2059/023

  Microembossing · CPC title

• B29C59/026

  of layered or coated substantially flat surfaces · CPC title

• G02B3/0031

  Replication or moulding, e.g. hot embossing, UV-casting, injection moulding · CPC title

• B29C43/58

  Measuring, controlling or regulating {(for bank adjustment in calendering B29C43/245)} · CPC title