Traveling Salesman Problem Based Auto-Router for Designing LEDs Applications with Conductive Inkjet Printing

Abstract

Printable electronic circuits have received a big adoption from a variety of users such as researchers, hobbyists, designers, and children. The designers want to use electronic circuits along with graphic design yet focus on the creativity and aesthetics of the design. However, current technology requires them to take care of the discouraging electrical behaviors of the circuits. Taking the task of lighting up a bunch of light-emmited diodes (LEDs) as an example, it sounds simple, but is posing significant challenges for inexperience users. Given the non-negligible resistance of conductive ink, it is not straightforward to generate a pattern that lights up the LEDs evenly. Furthermore, a large number of LEDs make it difficult and error-prone to wire them efficiently. It is possible to try existing auto-routers in computer aided design tools to automatically route these LEDs. However, being optimized to make circuits with highly conductive materials such as copper and gold, these auto-routers ignore the intrinsic resistance of the conductive ink. In this paper, we propose an LED auto-router which computationally generates a conductive pattern to balance brightness of multiple LEDs without the need of additional resistors. Our routing algorithm is based on the traveling salesman problem to find the shortest cross-less path through the LEDs, and thus minimize the ink consumption. It then adjusts resistances of the conductive patterns to regulate the current which flows through each LED.

Keywords

• conductive ink
• auto-router
• traveling salesman problem
• led
• uniform brightness