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the drop on demand printing module has two vacuum systems for ink meniscus control. one system for controlling the cmyk inks and one system for controlling the white ink. the main purpose of the vacuum systems is to provide slight vacuum pressures within the header tanks. due to the header tanks being located above the printheads, gravitational acceleration causes the fluid within the header tanks to exert a pressure on the fluid within the printheads. without vacuum applied above the fluid in the header tanks, the printheads drip out of the nozzle plates. the white ink requires a slightly different vacuum pressure due to differences in viscosity, density, and particulate concentration. for the cmyk vacuum system, each of the four header tanks has a port in the cap that is connected to a two way air valve with polyurethane tubing. the air valve provides a means of isolating the pressure in each of the header tanks from the other header tanks. in the case of a loss of power to the machine the air valve reverts to the “normally closed” position to maintain vacuum pressure in the header tanks. the white vacuum system operates in a similar manner with the main difference being that there is two header tanks and two header valves in the white system. the valve nearest to white header tank 2 is normally open while the other valve is normally closed. the two valves do not independently control the two header tanks. shutting the valve nearest the pressure dampener decouples both header tanks from the vacuum system.
8개의 솔레노이드 밸브(청록색, 마젠타색, 노란색 및 검은색 배출구 쌍)가 있으며, 이 밸브는 헤드를 폐기물 병으로 내보내는 잉크를 차단하는 일반 잉크 펌프와 함께 작동합니다.
