US Patent 7416276 Digitally active 3-D object creation system

A method of printing a three-dimensional object is provided. The method comprises providing a plurality of stationary printhead layer groups, each layer group comprising at least one printhead for printing a respective layer of the object; conveying a partially-formed object past the layer groups; and simultaneously printing material from at least one printhead in each layer group, such that a plurality of different layers are printed simultaneously by the layer groups.