Ink liquid viscosity control in an ink liquid supply system for an ink jet system printer

An ink liquid viscosity control system in an ink liquid supply system for an ink jet system printer, said ink liquid supply system comprising an ink liquid reservoir for containing a new ink liquid therein, and a sub tank for containing a predetermined ink liquid supply having an ink liquid level and for introducing the new ink liquid from said ink liquid reservoir and developing the ink liquid to be supplied to an ink droplet issuance unit included in the ink jet system printer, said ink liquid viscosity control system comprising:

• a float member being entirely submerged within the ink liquid contained in said sub tank, said float member having a specific gravity slightly greater than a specific gravity of a preferred ink liquid suited for the ink jet system printer;
• detection means disposed below the ink liquid level for detecting a movement of said float member while said float member is entirely submerged within said sub tank and producing an output signal indicative thereof, said movement of said float member being caused by a variation in the specific gravity of the ink liquid contained in said sub tank;
• and
• viscosity adjusting means for maintaining the viscosity of the ink liquid contained in said sub tank within a preselected range in response to said output signal produced by said detection means;
• said float member normally being entirely submerged, disposed in a lower portion of said sub tank and being unaffected by surface tension of the ink liquid level and being periodically, automatically moved upwardly, while still remaining entirely submerged within said ink liquid, in response to an increase in the specific gravity of said ink liquid above the specific gravity of said preferred ink liquid thereby actuating said detection means and producing said output signal for actuating said viscosity adjusting means for effecting a reduction in the viscosity of said ink liquid contained within said sub tank.