Light trap for uv radiation for curing ink on a printing substrate and printing machine including a light trap

A printing machine for printing on a printing substrate using an ultraviolet-curable fluid, the printing machine comprising:

• a printing head for transferring drops of fluid to the printing substrate;
• an ultraviolet (UV) emitter for curing the fluid on the printing substrate using UV light;
• and
• at least one first light trap for the UV light disposed between said printing head and said UV emitter on a first side of the printing substrate and/or at least one second light trap for the UV light disposed on a second side of the printing substrate, wherein said at least one first and second light traps each contain:
• a shaped body having at least three shape elements succeeding one another, said shaped body having a side facing the printing substrate and embodied to have said shape elements being step elements disposed in a stepped configuration, every one of said step elements having a pair formed of a step surface and a riser, said step surface and said riser having different inclinations relative to a direction of transport, said step surface has a step length L and said riser has a step height H,
• wherein the following applies:
• L>2H.