In Thermal Ink Jet printers, air bubbles generated in the ink fluid path have been identified as a cause of clogging the nozzles for ink supply, resulting in image defects. As a corrective method, a suction maintenance has been used to periodically discharge air bubbles from the nozzles with ink.However, the suction maintenance has had a problem of increasing the cost of the device and the volume of waste ink.To solve this problem, we have improved the structure of a manifold for ink supply to a head reservoir. This new manifold design enables air bubbles generated in the head reservoir to move to the upper part of the manifold by buoyancy, and also causes no pressure fluctuations at ink jetting.In addition, we have found a new reliable maintenance method named a “Super Heat Dummy Jet (SHDJ).” This method uses a boil phenomenon of ink in the head reservoir.With a smaller energy of drive pulses than that in normal printing, the SHDJ can raise the temperature of head until ink in the head reservoir boils. The boiling of ink makes air bubbles expand and move to the upper part of the manifold.As the result, we have realized a stable and simple air bubble management technology.