| 摘要 |
An ink jet printer includes a print head having a plurality of piezoelectric driving elements selectively energizable to cause ejection of droplets of ink through nozzles in a nozzle plate. Ink is supplied to the print head from an ink reservoir which is connected to a bellows device. The ink reservoir and the bellows device together form an air-tight container. The bellows device has a resilient form of construction so as to tend to increase the volume of the container. As a result, an appropriate underpressure is maintained in respect of the ink in the nozzles, such underpressure being necessary to prevent ink escaping from the nozzles under quiescent conditions. In operation, the bellows device progressively collapses so as to reduce the rate at which the underpressure increases as ink is ejected, thereby prolonging the period for which the underpressure is maintained within a desired operating range. In two other embodiments, the reservoir is enclosed by a piston or a membrane, both biased against collapse by a compression spring. In yet another embodiment, underpressure within the reservoir is maintained by a capillary tube that at one end is immersed in ink and at the other end is open to the exterior of the printer. |
