Directable Mirror - How It Works

A Directable Mirror is an inexpensive panel approximately one meter square and a couple of inches thick. It is sealed, with only electrical connections and has no external moving parts. It is capable of rapid internal movement of the mirrors. It works like this:
Take two flat rigid sheets separated by a large number of balls. Move one of the sheets and all the balls will rotate. Make the balls transparent with a reflective circle stretched across their centers, and the front sheet transparent. Arrange motors to move the other sheet and you have a directable mirror.

A 'Proof of Concept' can be constructed in a few seconds with the aid of some tennis or ping pong balls, a flat surface and a sheet of glass. Drop the balls on the surface, put the glass sheet on top and move it with your finger.

Now, for a comparison, take that sheet of glass outside and try and hold it still in a high wind, which is what a conventional concentrator has to do. If the sheet is much larger than a mirror tile you probably cannot hold it still, let alone aim it accurately,

The figure shows the concept in a more complete form with a casing, transparent front panel, the mirror balls and the motors for moving the rear panel.

The motors move the rear panel making the balls rotate thus moving the mirrors and changing the effective direction of reflection.

The balls and the front panel may be made from glass or clear plastic whichever is the most economical and effective, plastic balls and a glass panel seem likely to prove best.

The rear panel has a thin layer of foam in order to reliably grip the balls and compensate for small variations in ball sizes.

The details of the panel moving mechanism have been left unspecified. There are many workable mechanisms the choice is largely a production/economic one given easily achieved technical constraints on positioning accuracy and speed. A usable mechanism could easily be based around two of the the cheapest simplest stepper motors available and two rubber wheels.

The device is very simple and lends itself well to mass production. The described system easily matches the requirements outlined in the introduction for making solar concentration a practical system.

Australian patent no. 722115, US Patent no. 6227673, Patent pending Europe
How it works
Control System Design
Estimated Manufacturing Costs