Control method and apparatus for dispensing high-quality drops of high-viscosity material

An apparatus for rapidly dispensing minute quantities of a highly viscous material from a jetting orifice, comprising:

• a jetting chamber having sides, an open top, and a bottom having an opening that is in fluid communication with an exit orifice, the chamber being in find communication with an external fluid reservoir containing said material during use:
• a flexible diaphragm covering the open top of the jetting chamber, the diaphragm having a central protrusion extending toward the opening in the bottom of the chamber on one side of the diaphragm, the diaphragm being sufficiently flexible to deform into the jetting chamber a distance sufficient so that the central protrusion blocks the opening in the bottom of the chamber during use;
• a support structure having an opening aligned with the to of the jetting chamber and holding the diaphragm in the first position while allowing the diaphragm to deform to the second position during use;
• an impact element having an impact end spaced apart from the central protrusion on the opposite side of the diaphragm as the opening in the bottom of the chamber and aligned therewith;
• an adjusting mechanism configured to change the distance the impact element travels before it deforms the diaphragm;
• a support structure having an opening aligned with the top of the jetting chamber, the opening configured to allow the impact dement to impact the diaphragm to deform into the jetting chamber when the impact element is activated;
• and a sensing device configured to detect the distance between the impact element and the top of the diaphragm;
• wherein the central protrusion extends on both sides of the diaphragm and the impact element abuts one portion of the central protrusion and forces another portion of the central protrusion against the opening in the chamber bottom, with the protrusion not abutting opposing walls of the jetting chamber.