| 摘要 |
PURPOSE:To quantitatively detect the exchange time of a filter by simple, cheap and highly reliable means wherein the increase of the flow-path resistance of the filter is detected at the inlet side and the outlet side of the filter and form a differential pressure detector. CONSTITUTION:Ink is pressurized by means of a pump, and flows to a filter, an accumulator and a nozzle. A flow rate of 100cc/min continually flows at the fixed velocity of flow and is injected when a flow rate is approximately 5cc/min in case of a single nozzle and the number of nozzles according to a multi-nozzle system is twenty at that time. Pressure loss to the flow rate is value decided by mesh resistance at the initial stage of the filter used, but pressure loss value increases being proportional to the extraneous quantity of dust because dust loads with the augmentation of time used and the passage area of meshes is narrowed. Thus, pressure at the inlet side and the outlet side of a filter unit 1 is each guided to a differential pressure detector 2, a reed switch 3 works when difference between pressure at the inlet side and pressure at the outlet side becomes not less than fixed value, and the time when the filter is exchanged can be grasped. |
