Best way of oscilating a screen

[smithgi]

Hi,
I need to build an oscilating screen of about a4 size. The screen needs to be made from 1mm thick acrylic and be flat. It needs to oscilate up and down a total distance of 4cm (2cm up then 2 cm down) and do this a total of 30 times per sec , so 15 ups and 15 downs.

I'd like the motion to be as linear as possible , which due to inertia, and momentum I undestand is impossible to achieve totally, but as close to linear would be ideal.

Some ideas I have had.
1) some kind of magnetic coil, as if the screen were attatched to a large speaker through which a traiangular 16hz sounds wave was being played.
2) Some kind of cam
3) A compressed air oscilating valve of some kind.

Does anybody have any better ideas?

Thanks

 

[Danger]

Does anybody have any better ideas?

Not at the moment.

Welcome to PF, Smithgi. I started thinking as soon as I started reading, and my first thought turned out to be one of yours, as in attaching the membrane to a honkin' big speaker. I hadn't gotten to the point of figuring out a sonic signature for it, though. I was thinking along the line of some classic Stones or maybe a bit of Atomic Rooster, but that's just personal taste. I dismissed it before finishing the read, however, because I don't think that the spatial displacement with such a mechanism can be regulated as accurately as you seem to require, and might be hard to achieve at all with any reasonable volume level. That's an awful lot of movement.
My second idea was also one that you mentioned, as in a fast-acting cam. That still seems like the best approach. You'd likely need some sort of spring-powered return mechanism; there's a lot of inertial involved. Gravity won't likely cycle the thing quickly enough.
I'll think on it a bit, but you'd be best served by waiting for a real engineer to answer.

 

[256bits]

Reciprotating motion from a rod attached to a shaft, in which case the motion will be sine would be a simple option.