Projector or screen triggers form an interface between the projector and the screen. They make the screen directly controllable without having to operate the two devices separately. When a projector trigger is used, the screen automatically descends as soon as the projector is switched on. This happens because the projector sends a 12-volt signal to the trigger when it is switched on, which in turn causes the screen to descend.
Screen triggers are available in different versions. In addition to the classic wired trigger, there are also wireless devices. With a wireless trigger you can even control the screen through walls, as radio systems avoid interference with existing IR systems, for example, and do away with the line of sight otherwise required between receiver and transmitter.
Unlike a wired trigger, wireless triggers don't need a corresponding connection on the projector but can simply be connected to the IEC power connection. If you opt for a wireless trigger, you'll also need a radio receiver to which the trigger is paired. The trigger's transmission power can usually be adjusted continuously, so it can be optimally adapted to the requirements.
