This project was made by 3 students of Télécom ParisTech as part of the Embedded Systems course (ELECINF344/ELECINF381 aka ROSE). At the beginning in February 2012 our initial goal was to create a display device using persistence of vision. The main interest of this type of device is that we obtain images carved in our retina but the device is moving so quickly that we cannot see it. Thus our images seem to float in the air.
Many POV devices already exist but they are often limited to simple display patterns, such as clocks or moving text. Some of them can display pictures or videos but these media often have to be preregistered in a memory on the device. We wanted to create a universal device able to display whatever you want whenever you want.
Our solution was to build a blade that can be fueled while it is turning at 1000 rpm. On this blade we aligned 128 LEDs. A shift of half a LED on one half of the blade allowed us to have after a complete revolution a resolution of 256 pixels on the diagonal – we must mention here that for a question of modification of the maximum PCB size at our supplier we only put 112 LEDs so the videos that we display are cropped. These LEDs are driven by a FPGA that computes the position of the blade thanks to an encoder wheel and lightens the right pixels. It receives the pictures to display from a Gumstix, a tiny computer on which Linux is running allowing us -connected in wifi to the Gumstix- to easily display whatever standard video file we want.
After almost three months of work in a team of three here is the result of our work.