JEFFREY WOOLF of London is patenting (WO 97/08025) a silent car alarm.
The main feature is a windscreen made from an electrochromatic material, which
changes from clear to opaque when an electric current passes through it. Anyone
trying to hot-wire the car will trip a sensor and find that they cannot see
through the windscreen. Woolf suggests the windscreen could be patterned to
display a “stolen” message.
Alternatively, the car could be designed to have an opaque windscreen when it
is parked. To clear the screen, the owner would flip a secret switch or use
coded car keys.
