A ventilated face shield assembly with a glare shield which protects the face of the wearer from debris andor hazardous materials, such as biological materials, and is particularly well suited for medical and dental applications. The system includes a controller coupled to at least one input device with the controller operable to compute a reward offer. The inventive measures ensure, with simple means, a precise fuel metering in the multiple injection operating mode and thus enable an application of the multiple injection operating mode over wide operating ranges, particularly also in the low load operating mode and idle operating mode.