Meet LitSpin

Our goal is to build a 3D POV (Persistance Of Vision) display with no black zone in the middle.

Last week we mainly discussed the technical limits of our project. See here for more information.

Thinking about it, we discovered a number of challenges that we will have to face:

  • Our project will have a spinning part and a base, and we will have to find a way to transfer power and information between both parts:

Concerning the power transfer, we thought of induction, but the main constraint is the available power. We will need between 50 and 100W of power for the PCB, and there are not many induction transmitters that can transmit that much power.

As for the information, we only need to measure the speed of the motor and to send speed commands, so a Hall effect sensor for the measurement and an infrared sensor for sending commands should do the trick.

  • Our targeted resolution brings a few more constraints:

We want a framerate of 30fps, and with a radial resolution of 512 pixels the blink frequency for the leds will have to be at least 30kHz. Since we need a PWM resolution on 9 bits, we need a minimal PWM frequency of 7.7MHz, which is a serious constraint for the choice of the led drivers. And this is valid only if we don’t multiplex the leds, because multiplexing will increase that frequency.

That’s all we discussed, because we also had to do a first draft of the PSSC for last Friday’s presentation. We will continue this week to discuss these technical challenges.

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