Erm, the entire CD doesn't have to be in a dark environment, just the bit that contains the reading head. And even in this case, there is some leeway available as it doesn't have to be 100% dark, just with enough "contrast" in the light levels of laser/not-laser to accurately read the CD track.
As for removing fingers, these discs don't go round that fast, don't have sharp edges and have very little mass behind them so are largely harmless. still wouldn't recommend gently running soft skin (like fingers) on the edges when they're running, but they certainly wouldn't remove a finger. Biggest problem is likely to be the practical problems of keeping the disc spinning at a constant speed in an environment where there are things to get in it's way, dust, hair, dirt, etc to fall onto the disc and all manner of other problems. Besides which, how do you actually hold such a device and without jamming digits / clothes, etc into the mechanism or just dropping the headphone cable into it's mechanism?
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Dark environment ...
Erm, the entire CD doesn't have to be in a dark environment, just the bit that contains the reading head. And even in this case, there is some leeway available as it doesn't have to be 100% dark, just with enough "contrast" in the light levels of laser/not-laser to accurately read the CD track.
As for removing fingers, these discs don't go round that fast, don't have sharp edges and have very little mass behind them so are largely harmless. still wouldn't recommend gently running soft skin (like fingers) on the edges when they're running, but they certainly wouldn't remove a finger. Biggest problem is likely to be the practical problems of keeping the disc spinning at a constant speed in an environment where there are things to get in it's way, dust, hair, dirt, etc to fall onto the disc and all manner of other problems. Besides which, how do you actually hold such a device and without jamming digits / clothes, etc into the mechanism or just dropping the headphone cable into it's mechanism?
Nice concept, will never go anywhere.