If you have read my previous item on LED Indicators you will know what this is on about. If not, have a look back at my previous write-up. The following invention requires the use of multi-coloured LEDs as discussed in said paper.
A further application of the LED Indicators would be a changing licence plate. This would most probably be viewed as illegal but serious volumes of cash would be made available for such a device, albeit from dubious sources.
The creation of a licence plate made up entirely of black coloured LEDs that shone white when voltage is applied, would enable you to create letters and numbers of any shape (supposing your licences plates are black and white as they are here in my country). If your licence plates are black, simply display LEDs in the shape of the letters and numbers you require. If your plates are white, display the LEDs that should appear as the background to your letters and numbers.
By hooking the licence plate up to a small device, the plate’s figures are changed to whatever you want. This is especially useful for if you wish to send rude messages to the car behind you (as also discussed in the afore mentioned discussion.
Further advantages are the fact the speed-cameras (as operated in my country of dwelling) would have a hard time reading LEDs as the flash would ‘wash out’ the lights.