HYDRAULIC SYSTEMS FOR INK JET PRINTERS

摘要

A hydraulic system, suitably an ink supply system for an ink jet printer, wherein an upstanding tube (59) of a viscometer (55) is connected to supply line for liquid and a ball is movably upwardly and downwardly within the tube. A valve (57) controls a flow of liquid from the supply line to the tube (59). Control means cause the valve to open and allow liquid to flow into the tube so that the ball (58) is moved to an upper part of the tube. The valve is then closed and the time taken for the ball to fall through a predetermined distance through liquid within the tube is determined. This line represents the viscosity of the liquid within the system. If the value of viscositv determined from the time taken for the ball to descend is different from an optimum value, the control means operating a charging means which add a component to the liquid so as to move the viscosity towards the optimum value.