Abstract: A printer head includes a wireless print head provided with a memory buffer for storing data corresponding to at least one line of data. The print head is also provided with a motor and runs along a guide means in a self-propelled manner, the print head further includes power pick-up means for taking power for the motor from the guide means. In one embodiment for example the guide means are a pair of parallel metal rails connected to a power supply and the print head includes metal wheels and brush means. In this way the amount of cabling required to connect to the print head to a controlling computer may be minimized.