Abstract: An apparatus for controlling the pressure in an ink reservoir of an ink jet printer which includes at least one ink reservoir of an ink jet printer, a pressure applying device for applying a pressure in the ink reservoir, the pressure applying device communicating with the ink reservoir via a first conduit, a buffer reservoir communicating a gasteous medium with the ink reservoir via a second conduit different from the first conduit, a detection system for monitoring the actual pressure in the ink reservoir, the detection system including at least one electronic pressure sensor, and a controller for controlling the pressure applying means dependent on the actual pressure monitored by the detection system.