US Patent 7270405 System for priming a pagewidth printhead cartridge

An ink priming system for a cartridge unit of the type having a pagewidth printhead assembly in fluid communication with one or more ink storage compartments is provided. The system comprises a priming inlet of the printhead assembly for receiving a supply of ink for priming the cartridge unit, an ink flow passage providing fluid connection between the printhead assembly and one of the ink storage compartments, and a bypass flow passage providing additional fluid connection between the ink flow passage and the ink storage compartment. The ink supplied to the priming inlet of the printhead assembly flows from the printhead assembly to the ink storage compartment via the ink flow passage and the bypass flow passage to prime both the printhead assembly and the ink storage compartment with ink simultaneously.