3D Display
This project was just for fun. I love working with CAD programs and thought this would be a cool idea. The concept was to expand on the persistence-of-vision clocks I used to see around a lot and use the same idea but for a 3D display.
Persistence of Vision
The fundamental concept this was based on was something known as persistence of vision. Essentially, our eyes continue to perceive light for a short duration even after that light is no longer being emitted from that location. If I turn a stationary light on and off at a high enough frequency, it will appear to the unaided eye as simply on. Similarly, if I have a light that’s continuously on and move it quickly, it will appear as though there is a line of light, even though there is only a point light source.
This phenomenon was exploited in the creation of 2-dimensional clocks comprised of a base and wand. The wand had a set of LEDs built into it and the base oscillated the wand back and forth. During it’s sweep, the wand’s LEDs turned on and off rapidly to create a “solid”image: the current time.
Design
My idea was to take that design one step further and create a 3D display. Rather than oscillating a wand, I’d spin it 360°. Adding more wands stacks the 2D images, creating a low definition 3D display. I also reoriented the axis to be vertical.
The plan was to use (10) 5mm LEDs per wand and stack 12 wands, resulting in 12 x 20 x 360° resolution - enough to create simple images. The wands were offset a few degrees to make assembly easier, but were counterweighted to reduce vibration. LEDs weren’t placed close to the center of the wands for two reasons. The reduced rotational speed there would have a negative impact on the POV illusion and the wands were small (so they wouldn’t block the view of other wands), reducing space for additional wiring.
The final design could create a 120 pixel 360° image.
Result
Unfortunately, I didn’t have a chance to proceed any further on this project and was left with only some CAD files. This’ll be a project I’ll work on again eventually. My hope is to increase the resolution (more wands and more, smaller, LEDs) enough to run a little 3D animation on it. I think the biggest hurdle will be figuring out how to direct the microcontroller to create the 3D images. The simplest way is probably to specify the directions for each wand individually, but that’s fairly labor intensive for a single 3D image, let alone an animation’s worth. But I’ll cross that bridge when I get around to working on this again.