Electrostatic 3-D printer controlling layer topography using aerosol applicator

A three-dimensional (3-D) printer comprising:

• an intermediate transfer belt (ITB);
• a build material development station positioned to electrostatically transfer build material to said ITB;
• a support material development station positioned to electrostatically transfer support material to said ITB, said build material development station and said support material development station transfer layers of said build material and said support material to said ITB;
• a platen having a flat surface positioned to repeatedly contact said ITB, said platen moves relative to said ITB, said ITB transfers a layer of said build material and said support material to said flat surface of said platen each time said platen contacts one of said layers on said ITB to successively form a freestanding stack of said layers on said flat surface of said platen;
• a sensor positioned to generate a topographic measurement of said layer on said platen;
• a feedback loop electrically connected to said sensor;
• and
• an aerosol applicator positioned to propel said build material and said support material on to said layer on said platen,
• said aerosol applicator selectively propels different amounts of said build material and said support material to different locations of said layers, based on said topographic measurement from said sensor through said feedback loop, to adjust the amount and location of said build material and said support material propelled on to said layer, to fill in depressions of surface topology of said layers and to control flatness of said surface topology of said layers in said freestanding stack on said platen, and
• said sensor detects said depressions and supplies depths and locations of said depressions to said aerosol applicator through said feedback loop.