High performance embedded systems for digital laser marking and printing

Student thesis: Doctoral thesis

Abstract

Laser marking is a common part of many manufacturing processes in the industry, with great importance in the fast-moving consumer goods (FMCG) industry since respects the environment without losing productivity. The speed of production lines is a key determinant of the output capacity of many industries, but their scalability could be hindered by some fundamental limits of current laser marking technologies. Currently, most laser marking equipment is based on a single laser beam with the corresponding sequential processing that culminates in a performance bottleneck which limits printing production line speed to a de facto barrier of 8 m/s. In this thesis, I review state-of-the-art technologies, their limiting factors, and analyze how future systems can overcome them. I propose, implement and validate several platforms that overcome these barriers by using a matrix of laser beams from semiconductor laser arrays or fiber-coupled laser diode arrays, for its industrial use in high-speed printing and high-resolution printing (f-LDA) and very-high-speed coding (HP f-LDA) type of applications. In all cases, they are controlled in real-time by using an embedded high-performance computing reconfigurable architecture based on FPGAs. As an alternative to generating and processing multiple laser beams in parallel, I also propose to project images formed by laser beamlets onto surfaces. These images are generated using SLM or DLP technologies. To do this effectively, images must be rendered correctly to match the required resolution, grayscale, and print width; and the control system needs to calculate this information along with the desired position of the printed image and the speed of the product to be printed or marked, which can be acquired from industrial encoders and sensors. Additionally, I present a novel multi-beam method to print paper and cardboard without ink. The method is based on the carbonization of paper by a combination of lasers working on different wavelengths. A proof-of-concept system is created based on combining existing commercial systems to demonstrate the viability of the method. The results show that no debris is generated, and the quality of the mark is superior in terms of contrast and resolution to previously known methods. The industrialized solutions presented in this thesis can print images from 50 to more than 300 dpi resolution on printing substrates widths ranging from 570 µm up to 100 mm, at production line speeds of up to 16 m/s. The analysis performed suggests that even higher speeds could be achieved by investing in additional laser beams, leading to a full range of new applications in Industry 4.0.
Date of Award17 Jan 2022
Original languageEnglish
Awarding Institution
  • Universitat Autònoma de Barcelona (UAB)
SupervisorJordi Carrabina Bordoll (Tutor) & David Castells Rufas (Director)

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