Thermal ink jet printing apparatus

摘要

In a printhead assembly for a thermal ink jet printer there are a plurality of printheads mounted on a common heat sink, together with a heater and temperature controller for maintaining temperature of the printheads at an appropriate operating level. To prevent overheating of a printhead during periods of heavy use, the ink supply paths carrying ink to the printheads pass through, and receive heat from, the heat sink. The ink in each supply path then passes to the respective printhead via a tank, the position of which relative to the printhead establishes the ink pressure at the printhead discharge orifices. The tank is vented so that any air separating out from the ink can be removed. Capping means is provided to cap the ink discharge orifices when the printhead is idle and to prime/clean the printhead when required.