Analysis of roll-stamped light guide plate fabricated with laser-ablated stamper

• Published in: Optics and laser technology 2017-12, Vol.97, p.346-353
• Main Authors: Na, Hyunjun, Hong, Seokkwan, Kim, Jongsun, Hwang, Jeongho, Joo, Byungyun, Yoon, Kyunghwan, Kang, Jeongjin
• Format: Article
• Language: English
• Subjects: Chemical etching; Computer simulation; Injection molding; Laser ablation; Lasers; Light; Light Guide Plate (LGP); Liquid crystal displays; Luminance; Micromachining; Optical properties; Optical simulation; Roll-stamping; Simulation; Stamping; Studies; Transcription
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2017.07.006

•The micro patterns were formed on a metal stamper using Nd:YAG laser processing.•LGP fabricating tests were performed with four different roll pressures.•Simulation results showed good agreements with optical performance of LGPs. LGP (light guide plate) is one of the major components of LCD (liquid crystal display), and it makes surface illumination for LCD backlit. LGP is a transparent plastic plate usually produced by injection molding process. On the back of LGP there are micron size patterns for extraction of light. Recently a roll-stamping process has achieved the high mass productivity of thinner LGPs. In order to fabricate optical patterns on LGPs, a fabricating tool called as a stamper is used. Micro patterns on metallic stampers are made by several micro machining processes such as chemical etching, LIGA-reflow, and laser ablation. In this study, a roll-stamping process by using a laser ablated metallic stamper was dealt with in consideration of the compatibility with the roll-stamping process. LGP fabricating tests were performed using a roll-stamping process with four different roll pressures. Pattern shapes on the stamper fabricated by laser ablation and transcription ratios of the roll-stamping process were analyzed, and LGP luminance was evaluated. Based on the evaluation, optical simulation model for LGP was made and simulation accuracy was evaluated. Simulation results showed good agreements with optical performance of LGPs in the brightness and uniformity. It was also shown that the roll-stamped LGP has the possibility of better optical performance than the conventional injection molded LGP. It was also shown that the roll-stamped LGP with the laser ablated stamper is potential to have better optical performance than the conventional injection molded LGP.