Method and apparatus for securing uniformity and solidity in liquid jet electrostatic applicators using random droplet formation processes

摘要

Uniform application of a controlled relatively small liquid volume per unit area to a moving fabric substrate is obtained even though application is made using a liquid jet electrostatic applicator which employs random drop formation processes. Repetitive print times during which randomly formed droplets are passed onto the substrate along a linear orifice array are controlled so as to have a minimum duration sufficiently large as to average out expected random variation in droplet formation processes occurring along the orifice array. At the same time, the center-to-center spacing of each printed pixel (during which randomly formed droplets are intercepted so as not to fall onto the substrate) is controlled so as to maintain a desired relatively small controlled liquid volume per unit area within the fabric substrate section to be printed. In one exemplary embodiment, the print times are maintained in excess of approximately 200 microseconds and/or so as to insure that the expected standard deviation of liquid volume printed onto the substrate during each print time is less than approximately 0.2.