An automatic steering system for a work vehicle comprises a position sensor for detecting a position of the vehicle, a memory for storing information about a nominal path of the vehicle and a control unit coupled to the position sensor, to the memory and to a steering actuator for steering the vehicle. The protection circuit is designed so that the electric strength needs to match only the actual maximum battery voltage, thus requiring little real estate on an IC chip and also allowing most components to be integrated. The resulting directional histogram model is substantially invariant to scaling and translation. The free end of the hose is fitted with a resilient frusto-conical protective hood 20. When the printer 10 is activated, after the intermediate transfer belt 52 starts to rotate, the photoconductive drums 61 start to rotate one after the next starting with the one disposed most downstream along the rotation direction of the intermediate transfer belt 52.