Abstract: Method and apparatus of identifying ink stored in an ink-jet cartridge are to change the electrical property such as resistance or capacitance of the ink and to cooperate with a detector to achieve the goal of identifying ink. The method comprises: adding special additive such as salt additive or acid additive into the ink or changing the ratio of the components in the ink, and further providing a detector for detecting the electrical property of the ink and doing logical judgment to identify whether the ink stored in the ink-jet cartridge is the original factory ink or not. The preferred embodiment of the apparatus of identifying ink in ink-jet cartridge is to form the detector on the IC of the print head directly to achieve the goal stating above of detecting the electrical property of the ink stored in the ink-jet cartridge.

Abstract: The present invention provides any ink jet pen an apparatus for storing and printing ink, wherein a valve is connected between the ink reservoir and the ink chamber for controlling the ink flow between the ink reservoir and the ink chamber and adjusting the air pressure in the ink chamber to keep the pressure in the ink chamber within the allowed range as the ink gradually gets depleted or the environmental pressure changes. The valve having a plunger and a plunger chamber, wherein the plunger chamber is connected to the atmosphere via an atmospheric opening and connected to the ink chamber via a feedback opening which adjusts the pressure in the ink chamber to move the plunger. When a difference between the atmospheric pressure and inner pressure of the ink chamber develops, the plunger will be pushed by the pressure of the atmosphere or the ink chamber to determine whether the ink reservoir is connected to the ink chamber and to adjust the ink chamber inner pressure.