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Point of hors d'oevre
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The idea is for Venetian blinds to be open when it's sunny out/darker inside, for lighting, and then be closed when it's dark out/lighter inside, for privacy. Instead of rigging up stepper motors and light sensors, though, it would be great if the blinds were made of a material that folded up on their
own simply because of the difference in light from one side to the other.
I'm not sure if this could be done with a clever application of bimetallic strips. Presumably you'd need to make the strips respond mostly to heat from radiation (which would be different from one side to the other) and not to heat absorbed from the air around them (which would be the same on both sides), which would make things difficult.
Phototropism of plants seems to be too complex to mimic.
Maybe there is another substance/design that would respond to the light itself, instead of heat?
I've baked a quarter of it, at least.
The lampshade bends out and opens up by the heat when the lamp is turned on [omegatron, Jan 03 2007]
Wax in a piston
[goldbb, May 18 2009]
My current solution
It SEEMED so obvious. [WcW, May 18 2009]
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||I don't think bi-metallic strips need a temperature gradient, but they might be colder during the day in winter than on a summer night.
||Using light directly: Maybe use the photoelectic effect to charge the material during daylight, then somehow use self-repulsion or attraction to other stuff so it moves the right way.
||Unpowered automatic windows are
available for greenhouses, so the principle
of moving a reasonably sized object with
heat changes is sound. It may not transfer
well to houses as we smooth out the large
day/night temperature differences with
insulation and heating. [+]
||How do greenhouse ones work?
||// Maybe use the photoelectic effect
||I believe that would only be useful in a vacuum?
They have a piston with wax inside that expands and pushes the rod out like a hydraulic cylinder.
||If the insulation is a problem, maybe have a place for the wax uninsulated from outside but insulated from inside.
||How about a wax thermostat device?