DROP CHARGE SENSING APPARATUS FOR AN INK JET PRINTING SYSTEM

摘要

An inductive charge sensing device is disclosed in accordance with the teachings of the present invention for use with an ink jet printing system wherein ink under pressure is applied to a nozzle and ink emitted by the nozzle thereafter breaks up into a series of drops which are electrostatically charged and subsequently deflected in order to achieve controlled printing upon a recording surface moved in front of said apparatus. The charging and deflection of individual droplets is effected under control of an applied video signal. In order for the proper information to be recorded, the charging and deflection operation must be performed in precise synchronization with the ink droplet formation. As droplets are emitted from the nozzle, the charge sensor detects charges impressed on said droplets passing adjacent to but in non-impinging relationship with said sensor and a signal is developed which may be used to control an electrical or electromechanical drop forming means associated with said nozzle and ink supply.