Hi everyone, I intend to build a persistence-of-vision volumetric display by rotating a 16*16 matrix of SK9822 ARGBLEDs. I'm not sure this is the right place for the question but I'm wondering if some people with experience might know. I've found that persistence of vision takes place smoothly at around 20 'fps'. This would dictate that the display rotates at least 20 times per second (1200 RPM). What I'm wondering is if this works given that the back side of the LED matrix board would be blank (no LEDs). Since half the time a blank board would be facing the viewer, would this increase the required rotational frequency to avoid flicker? I've found parts that work with the 20 FPS assumption, but I'm not sure if it'll be so easy at, say, 40 FPS, as this could require faster LEDs and a faster motor.
Half - are you sure? I'm not sure along which axis the display will rotate relative to the viewer and what you'll show on it. Maybe a little sketch/diagram to clear things up? It's evidently clear in your head, but I may not be the only one struggling with how you envision this physical setup.
Here, I whipped up this basic animation in Blender. Assume the side with colored squares has the LEDs. The other side is the back of the PCB.
Yeah, I figured that.
Are you really going to spin a 16x16 led panel at ~1000RPM? That sounds challenging. How are you planning to make the electrical connections on the rotating joint? A slip ring connector rated for such speeds sounds pretty expensive.
If you're concerned about the 'dark side', you could mount two panels back to back. It'll double your data transfer requirements, but it'll probably look a whole lot better.
You're right, a slip ring was going to be real tough to use, that's why I'm looking at wireless, which I believe will work. I found this on mouser which can do 5V 1A. The problem with doing two panels is that the power requirement is doubled, and 1A is cutting really low already.
By the way the matrix will be made of 2*2 mm LEDs so it'll be pretty small. Any thoughts on the speed, will having a 'dark side' mean it needs to spin twice as fast??
I'm afraid you'll have to try; I don't think there's a reliable way to tell at a theoretical level. To make matters worse, human perception varies pretty wildly among individuals, so what appears as smooth to one observer will still be choppy to another.
Even though the device is small, I'd recommend running it inside some kind of transparent enclosure. The thought of a kid sticking their fingers into this while it spins at 1000rpm....ouch!
I see. Perhaps I'll make the build specs a high estimate (30RPS?). I think the LEDs can handle that, though even at 20RPS a refresh rate of over 1kHz is required. The next tricky bit will be the motor. I'm probably going to make another post regarding that soon.
I was really just wondering if anyone on here had experience with such things and could give me a pointer. One of the videos I saw that motivated me to try this used a single panel, though the creator didn't comment on how this affected the outcome.
Either way, the display should be visible to some extent at 20 RPS, but I'm trying to figure out how to minimize flicker before selecting a design, ordering parts, and assembling.
Also the prototype may be open, but once its running consistently it'll need an enclosure.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.