:: spoke n' light ::
overview | sketches | prototype-I | prototype-II | prototype-III
A thin strip of LEDs mounted on a bicycle wheel creates a semi-transparent screen on which various images and animations can be displayed. The complete circuit (LEDs, microprocessor, battery etc.) is placed on the rotating wheel. A magnetic switch "ticks" the microprocessor every time the wheel has completed a circle, so that the rotation speed (and "zero" location) can be determined.
LED Super-resolution. By using two LED strings shifted by 1/2 the diameter of an LED, the dark areas between two adjacent LEDs can be filled.
Persistence of Vision. This installation uses a phenomenon known as "Persistence of Vision" to create the illusion of a stationary image. "Persistence of Vision" is the ability of the eye to perceive a series of rapid still images as a single moving image by retaining each impression on the retina for about one-tenth of a second.
By changing the state of the LEDs over 1000 times per second and synchronizing this modulation with the speed of rotation of the wheel, the illusion of a stationary or animated image is created.
Cheesy but effective. I tested two animations on my latest set of software and hardware. Results were pretty good... She said "yes" :-)
Facelifting. For display at the ITP Winter Show, I sanded the bike to restore its metal color and mounted it on a black table. By using some memory management tricks I was also able to increase the radial resolution threefold.
