Multicolor liquid ink jet print head

#This invention relates generally to ink jet print heads and more particularly concerns multicolor ink jet print heads in which the inks must be fed in isolation from one another to separate nozzles.

#In a monochrome ink jet print head, liquid ink is contained in the interior of a print head body, perhaps retained within a foam material. If the print head is arranged for operation so that the nozzle assembly is at the bottom of the print head, for example, an exit port is provided in the bottom of the print head body to allow ink to flow to the nozzle assembly. In the case of a thermal ink jet printer, the nozzle assembly includes a heater chip and nozzle plate which cooperate to form an ink supply area downstream of the exit port and channels running to individual nozzle openings for the emission of ink drops to effect printing.

#A multicolor ink jet print head contains a number of separate ink-containing chambers separated from one another by walls in a print head body. For example, a three color print head for cyan, magenta and yellow inks includes three separate ink chambers, each of which would typically include an individual foam element for the ink therein.

#FIG. 1 is a front view, with portions removed, of a multicolor liquid ink jet print head;

#FIG. 2 is a side view of the print head of FIG. 1, with portions removed;

#FIG. 3 is an exploded view of the print head of FIG. 1;

#With initial reference to FIGS. 1-5, an ink jet print head 10 includes a lid 11 and an upper ventilator 12 received beneath the lid on the top of a print head body 13. These components of the print head are plastic, with the presently preferred material being a modified polyphenylene oxide, Noryl SE-1 of GE Plastics. The material selected must be moisture resistant and chemically compatible with the components of the ink to be held in the print head body.

#The print head body 13 includes interior walls 14 and 16, which serve to divide the body 13 into three interior ink chambers 17, 18, and 19. Each ink chamber 17, 18, and 19 contains a foam block 21, 22 or 23, respectively to hold each of the three colors of ink to be carried in the print head body 13. The foam blocks are a reticulated polyether-polyurethane foam, with the presently preferred material being Foamex Corp. SIF Felt No. 03Z70A0532.

#Each of the ink chambers 17, 18, and 19 includes in a lower, front portion thereof a chimney, or a stand pipe, 26, 27 or 28, respectively. These stand pipes 26-28 extend slightly above a bottom surface 29 of the ink chambers. Each chimney 26, 27, and 28 has a disk-shaped filter 30, 31 or 32, respectively, secured on its upper end. The filters 30-32 are made up of a dynamesh filter medium rated at 20 microns, available from Fluid Dynamics Corp., Deland, Fla.