US Patent 7770567 Safety trigger for a crossbow

A trigger assembly for a crossbow comprises a caliper, a trigger mechanism, a safety mechanism, and a bolt sensor. The caliper retains or releases a bowstring. The trigger mechanism holds the caliper against its bias to retain the bowstring, or releases the caliper to release the bowstring and fire the crossbow. The safety mechanism in a safety-on arrangement blocks the trigger mechanism or in a safety-off arrangement enables movement of the trigger mechanism. The bolt sensor biases the safety mechanism toward its safety-on arrangement when no bolt is present, or is held against its bias by a bolt to enable movement of the safety mechanism into its safety-off arrangement.