Linear energy control of laser drilling and its application in the repair of TFT-LCD bright pixels

Abstract

Laser drilling is an energy dependent process in which energy consumption is linearly proportional to the thickness of the material being drilled. Thus, providing linear output power from the laser can provide considerable advantages in the repair of devices such as TFT-LCD pixels. Unfortunately, the non-linear energy characteristics of lasers require compensation to achieve linear power output. Conventional compensation schemes use laser power meters that require repeatedly switching the laser system off and on again. This study developed a software-based energy compensation method to provide optimized energy output and continuous linear laser energy. This software solution enables the measurement of laser energy in a fixed period and its manipulation using a compensation table, which eliminates the need for a laser power meter and enables the system to remain in operation during laser power calibration. The proposed method provides linear output in which the linear energy proportion (R2) reaches 0.9988 and provides a very stable power source. We applied this method to repair bright pixels in LCD panels, achieving a success rate of 86 %. In addition, the proposed method eliminates the need to remove the LCD casing from the fabrication module, thereby increasing the efficiency of production.