| 摘要 |
<p>An ink jet printer includes an ink chamber (14) supplied with ink from a source (28) through a filtered settling tank (40). A crystal (16) causes perturbation in an ink jet issuing through nozzle outlet (20) and unused drops are collected in sump (88). The tank (40) has valved inlet (30) and valved outlet (32). Outlet (32) is connected to rapid depressurising device (56) comprising a cylinder (62) housing a ball (70). Screw (68) limits the rise of the ball (70). Cylinder (62) is connected by pipe (76) to reserve reservoir (78). Reservoir (78) is connected by pipe (86) to sump (88) so that the liquid level is maintained at level (84). Level (84) is above the end of pipe (76) and below the level of the nozzle (20).
<??>When the printer is to be shut down, the valved inlet (30) is closed and the valved outlet (32) opened. The tank (40) and chamber (14) are consequently rapidly depressurised by a surge of ink flowing through tube (58) which is accommodated in cylinder (62) by the ball rising and displacing ink into reservoir (78). When the ball is stopped, ink flow is restricted to the narrow annulus between the ball (70) and the walls of the cylinder. This maintains the pressure in the ink upstream of the ball, that is in the head, above atmospheric and air is stopped from entering the head. </p> |
