Genomskinlig touchsensor för pålitlig styrning av RGB-lysdioder

Sammanfattning: Many electronic products of today utilize some form of touch technology. Looking at everything from smartphone screens to ticket vending machines, it is obvious that the number of applications is big and the demand is huge. Touch technologies generally require no force to use, which reduces mechanical wear-and-tear and thus increases their lifespan. In this thesis, a touch system was constructed to control RGB LEDs. The sensor surface was made from a white, semi-clear plastic, through which the LEDs’ light should be visible. Since the plastic both needed to transmit visible light and act as a touch surface, a problem arose: how do you construct a transparent touch sensor that can control RGB LEDs in a reliable way? Firstly, this thesis describes and discusses many of the different available touch technologies and their strengths and weaknesses. From this information, a specific sensor technology was chosen, from which a prototype of the transparent touch sensor was built. The sensor prototype was a capacitive sensor, made from a thin metallic mesh, placed on the back of the plastic surface. Using an embedded system, based on a differential capacitance touch IC and a microcontroller, the capacitance of the sensor was measured and converted into signals which controlled the LEDs. In order to ensure the sensor’s reliability, the environmental factors which affected the sensor had to be determined and handled. To do this, measurements were performed on the sensor to see how its capacitance changed with environmental changes. It was concluded that moisture, temperature and frequency had negligible effect on the sensor’s dielectric properties. However, it was discovered that proximity to ground greatly affected the sensor and that the sensor was significantly dependent on its enclosure and grounding.