US Patent 7210405 Printer ink supply system with viscosity control

An ink supply system is used with a printer of the type in which ink is deposited in an engraved receiving region on a cliché plate and is scraped from the plate leaving ink in the receiving region. The ink supply system includes an ink cup having a hollow interior defining an ink reservoir and defining an outer edge. The outer edge has a doctor blade formed thereon for engaging and scraping the plate. The ink cup has an inlet and an outlet. A pump has a suction side and a discharge side with the suction side in flow communication with the cup outlet for drawing ink from the cup. A viscosity controller is in flow communication with the pump discharge and receives ink from the pump. A flow conduit extends between the viscosity controller and the ink cup for providing a flow of ink from the viscosity controller to the ink cup. The pump draws ink from the cup to create a negative pressure within the cup and the negative pressure within the cup draws ink from the viscosity controller to the ink cup through the flow conduit.