Patent ID: 7121653

Claim:
A negative-pressure control device for an ink-supply system, said control device comprises: a box having thereon a hole, and connected with a water inlet and a water outlet, said box is provided therein with a liquid level gauge to control and maintain a constant level of ink in said box; an ink-jet head having on its top an ink inlet and an ink spilling port both communicating with an inner receiving space of said ink-jet head, said ink-jet head has on its bottom an ink-jet outlet to jet print downwards; an adapter provided with a connecting hole, a siphon pipeline and a reflux pipeline, said siphon pipeline is connected between said box and said ink-jet head, and said reflux pipeline makes communication of said siphon pipeline with said ink spilling port; and a set of releasable check valve having an end connected with said connecting hole of said adapter, and having another end connected with an air drawing pipeline to draw air in said ink-jet head and said adapter to make states of negative-pressure; thereby, said ink in said ink-jet head and said water outlet is subjected to attraction of air with said negative-pressure, to maintain a balance state preventing said ink from dropping; when said ink-jet head jets prints downwards, said ink-jet head is automatically supplements ink to get an effect of continuous jet printing, the amount of said ink in said box thus is synchronically supplemented by controlling of said liquid level gauge.