The entertainment industry is experimenting with “self-destruct” rental DVDs you won’t have to return to the shop, as they only play for a couple of days. General Electric and Flexplay Technologies admit in recent joint patent filings (W0 03/ 089528) that some such systems may be “defeatable” and fear this may start a cottage industry for rejuvenating dead DVDs.
If a disc is coated with leuco methylene blue – an oxidised form of the dye – it changes colour in air and stops playing. But exposure to light may bleach the dye and make the disc playable again. GE and…
