Abstract: Energy applied to a heater for ejecting an ink is set to more than bubble generation threshold energy Eth and less than predetermined energy Eo, or to more than the predetermined energy Eo. Thereby, when an image to be printed is one of low ejection duty, an ejection where a bubble communicates with the atmosphere before the ink droplet separates from an ejection port (BTHJ ejection) is performed. On the other hand, when the image is one of high ejection duty, an ejection not communicating with the atmosphere as above (BUBBLE-JET ejection) is performed. As a result, an increase of ink mist due to satellites can be suppressed as a whole even if satellites are increased because of BTHJ ejection. When the ejection duty is high, generation of satellites themselves is reduced, thereby suppressing increase of ink mist.

Abstract: In an inkjet recording head having a plurality of ink ejecting ports and a plurality of energy generating elements respectively positioned in confrontation with the ink ejecting ports for generating energy utilized to eject ink from the ink ejecting ports, the plurality of ink ejecting ports and the plurality of energy generating elements being divided into a plurality of blocks, and the ejecting ports and the energy generating elements being timeshapred driven in a sequence of the blocks in a common driving period, the plurality of energy generating elements are disposed in an approximate sraight line, and the respective ink ejecting ports are off-set with respect to the energy generating elements in a projecting relationship in correspondence to the sequence of the timeshapred drive.

Abstract: An ink jet head is provided with an orifice plate having a plurality of discharge ports being open thereto. This ink jet head comprises evaporation suppressing groove in the vicinity of the discharge ports. With the arrangement thus formed, it becomes possible to heighten the humidity in the atmosphere in the vicinity of discharge ports, hence suppressing the evaporation from the discharge ports for the prevention of unstable discharges.

Abstract: In order to enable high speed printing with maintaining reliability of ink ejection, an auxiliary hole is provided in an upper wall forming a liquid passage. An opening area of the auxiliary hole is set to be greater than or equal to three times of an opening area of an ejection opening, and a minimum distance between the auxiliary hole and the ejection opening is set to be greater than or equal to three times of a height of the liquid passage.

Abstract: An ink jet head comprises a plurality of discharge pressure generating elements serving as the discharge pressure source for discharging an ink droplet, an orifice plate having a plurality of ink discharge ports corresponding to the respective discharge pressure generating elements formed therefor, an ink supply port for supplying ink and a nozzle wall forming an ink flow path communicating the ink discharge ports with the ink supply port. The orifice plate and the nozzle wall are formed by resin material, and also, a thin metallic film is formed on the outer surface of the orifice plate. If desired, a water-repellent film is formed further on the surface of the thin metallic film. With the metallic film formed on the surface of the orifice plate, the moisture in ink is effectively prevented from being evaporated. Further, with the provision of the metallic film, it becomes possible to perform the eutectoid plating for the formation of the water-repellent film.

Abstract: There is disclosed an ink jet head comprising plural discharge energy generating elements for generating energy to be used for discharging ink droplets, ink discharge openings for discharging the ink droplets, a substrate bearing thereon an array of the plural discharge energy generating elements and an ink supply aperture consisting of a penetrating hole extending along the direction of array of the discharge energy generating elements, and an orifice plate provided with the ink discharge openings, in which the substrate and the orifice plate are mutually adjoined to define therebetween ink paths connecting the ink discharge openings and the ink supply aperture, wherein the orifice plate comprises plural projections in a position corresponding to the ink supply aperture.