| 摘要 |
<p>The present invention relates to a method for monitoring the viscosity of ink in an ink jet printer, notably a continuous ink jet printer, during operation of the ink jet printer, which method is characterised in that it comprises the steps of: (a) filling a vessel (20) with the ink whose viscosity is to be monitored to a predetermined upper level; and (b) measuring the time taken for the ink to drain from the vessel between that predetermined upper level and a predetermined lower level in the vessel through an outlet (22) having a flow throughput which is affected by changes in the viscosity of the ink flowing through it. The invention also relates to an ink jet printer having a reservoir (1) for ink to be ejected as droplets through a nozzle orifice, characterised in that the printer is provided with a device for monitoring the viscosity of the ink, characterised in that the device comprises a vessel (20) adapted to receive ink from a point in the flow path of ink between said reservoir and said nozzle orifice, said vessel having an inlet (25) adapted to receive said ink and an outlet (22) by which said ink is allowed to drain from said vessel; said vessel having a sensor (26) adapted to sense an upper predetermined level of ink in said vessel and a sensor (29) adapted to detect a predetermined lower level on ink in said vessel; said inlet having valve (24) means for interrupting the flow of ink to said vessel so as to permit the ink level in said vessel to fall as ink drains from said vessel; and timer means adapted to monitor the time taken for the ink level in said vessel to fall from said upper level to said lower level.</p> |
