FTIR TOUCH PANEL FOR A MOBILE DEVICE Kari

FTIR TOUCH PANEL FOR A MOBILE DEVICE Kari Severinkangas, MIT 0 SY School of Engineering, Information Technology, Software Engineering Introduction The thesis was done in a company named Tacto. Tek, which is specialized in embedding electronic components into 3 D molded plastic. The technology allows curved touch interfaces produced cost efficiently by integrating infrared transmitters and receivers into molded plastic. Methods A prototype device was developed with PC connectivity in order to read the runtime data to be displayed in the signal monitoring application and to feed the algorithm on computer. A simulator SW was developed to explore different kinds of methods for calculating touch points. In the end the algorithm was integrated in MCU and the prototype’s performance and accuracy was evaluated by using a robot tester and other manual measurement methods. FIGURE 1. Design mock-up Objectives How to design an optical touch application that runs on a microcontroller of limited power and processing resources providing touch functionality that meets today’s standards? The basic concepts of infrared detection and the frustrated total internal reflection (FTIR) phenomenon are gone through. The SW and HW Master’s Thesis signal processing architecture, and algorithms ECTS credits: 30 are described at high level. 2013, Autumn Date of publication: Instructor: Timo Vainio FIGURE 2. Prototype HW and robot tester Results The developed touch application has an accurate multi touch functionality and allows input to be given with gloved hands. In addition, a touch size, shape and relative pressure are calculated This study proves that this technology has potential and it can compete with the existing technologies providing a good performance, accuracy and a multi-touch functionality. FIGURE 3. PC SW showing results read from the touch controller Conclusions The capacitive technology is dominating the mobile device markets today, thus it sets a benchmark for other technologies. The challenge in the FTIR touch is the activation sensitivity compared to the capacitive, which does not need a physical contact for a touch activation. On the other hand the FTIR panel provides a more natural and secure input method for applications where unintentional touches should be avoided. This could be advantageous in consumer applications where usually buttons and switches have been used, for example household and automotive applications.