Transcript Severinkangas Kari FTIR touch poster

FTIR TOUCH PANEL FOR A MOBILE DEVICE
Kari Severinkangas, MIT0SY
School of Engineering, Information Technology, Software Engineering
Introduction
The thesis was done in a company
named TactoTek, which is
specialized in embedding electronic
components into 3D 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 architecture, signal
processing and algorithms are
described at high level.
Master’s Thesis
ECTS credits: 30
Date of publication: 2013, Autumn
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 multitouch 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.