Birch, Stewart, Kolasch & Birch, LLP
Ink-jet cartridge
 An ink-jet cartridge for an ink-jet pen is disclosed. The cartridge includes a back pressure chamber in which the level of ink will be self-adjusted to provide ink for ejection and prevent ink from leakage. The ink-jet cartridge includes an ink reservoir for storing ink, a back pressure chamber, a print ink chamber and a print head. The back pressure chamber has one end fluid-communicated with the ink in the ink reservoir, and the other end fluid-communicated with the print ink chamber via an overflow vent which is at a position higher than the ink level of the ink reservoir. A suitable back pressure is applied to the back pressure chamber and the print ink chamber so that, when printing, the increased back pressure in the print ink chamber sucks ink from the ink reservoir through the overflow vent into the print ink chamber; while, when not printing, the extra height of the ink in the back pressure chamber relative to the ink level of the reservoir balances the back pressure at the back pressure chamber and the print ink chamber to prevent ink leakage from the print head. Therefore, it doesn't need a valve or a movable element to accomplish the ink supply and leakage prevention. 
WiserTek International Corp.
B B
B41J B41J
inventional inventional
Ji-Chen Ming-Hsun Huan-Kun
Wu Yang Chen