Patent ID: 7731343

Claim:
A negative pressure ink supply system comprising: a plurality of primary ink cartridges; a plurality of ink pumps; a plurality of secondary ink cartridges; a plurality of jet heads; a negative pressure ink cartridge assembly having a plurality of negative pressure ink cartridges provided between the plurality of secondary ink cartridges and the plurality of jet heads; each corresponding primary ink cartridge, ink pump, secondary cartridge, negative pressure ink cartridge and jet head being connected in serious by ink tubes; each liquid level in the plurality of secondary ink cartridges being lower than each surface of the plurality of jet heads and being adjustable; each negative pressure ink cartridge having: a tee valve, a cleaning solution tube and a jet head ink tube, which are located its outlet, a screw plug being set on top of the negative pressure ink cartridge and being used in conjunction with an air extract opening of the negative pressure ink cartridge, a feed-through link being used to facilitate passing of ink or cleaning solution and to assemble the plurality of negative pressure ink cartridges together; a joint of ink inlet for the ink tube connecting the negative pressure ink cartridge and the secondary ink cartridge; and an orifice is provided on a surface of the negative pressure ink cartridge.