US Patent 7938522 Printhead with porous catcher

A printhead includes a catcher and a negative pressure source. The catcher includes a liquid drop contact structure. The liquid drop contact structure includes a plurality of pores, each of the plurality of pores having a substantially uniform size when compared to each other. The plurality of pores have a critical pressure point above which air can displace liquid from the plurality of pores. The negative pressure source is in fluid communication with the plurality of pores of the liquid contact structure. The negative pressure source includes a pressure regulator to control the negative pressure such that the negative pressure remains below the critical pressure point of the plurality of pores of the liquid drop contact structure.