Pressure regulating apparatus for ink delivered to an ink-jet print head. The apparatus includes an ink pressure regulating valve that is urged shut by a plurality of coned disk springs that apply a substantially constant force to the valve over the length of its travel. The coned disk springs are...http://www.google.com/patents/US5737001?utm_source=gb-gplus-sharePatent US5737001 - Pressure regulating apparatus for ink delivered to an ink-jet print head
