Abstract: A microphone is provided for converting the impact force of a moving charged droplet into a corresponding electrical signal. A vertical support member supports a diaphragm in the path of the moving droplet. The diaphragm flexes or vibrates in response to a group of impinging droplets. A bimorph piezo-electric element is in contact with the diaphragm to move therewith and is fixedly secured at its opposite end to an adjacent housing member. The bimorph generates an electrical signal in response to bending stresses created when the bimorph is bent.

Abstract: An improved system for determining the optimal phase time to charge a liquid stream emitted from a jet as it evolves in form from a continuum to a separatuum of droplets wherein the optimal time for achieving the desired level of charge on a given droplet may be had by applying the charge immediately prior to break-off of droplets. A particular use of the system is in an ink jet droplet apparatus having a controlled liquid stream of ink that is separated into droplets by a sonic transducer and then charged by a pair of charging plates in a dynamically controlled manner at an optimal phase time as correctably tested by the system for subsequent static deflection of the charged droplets to a desired portion of a document to form printed characters.

Abstract: A generator for producing droplets of liquid by subjecting a confined body of such liquid to varying pressures at a given frequency and causing such liquid to issue from a discharge orifice first as a continuous stream and thereafter to break up into a succession of separate droplets. A particular use of the generator is to produce a controlled stream of ink droplets for the purpose of forming printed characters on documents. It accomplishes this object by making use of acoustic and ultransonic vibrations in a body of ink contained in a cavity of tapering dimensions having an ink intake passage and a discharge orifice, and causing periodic variations (or varicosities) in the hydraulic pressure at the discharge orifice which in turn causes the issuing stream of ink to break up into uniformly spaced apart fine droplets of ink.

Abstract: An ink jet printer has a printing head which contains at least one cavity with a discharge orifice therein for dispersing droplets of ink onto a medium for printing thereon. Means are disclosed herein for maintaining the temperature of the ink in the cavity at a preselected value prior to dispersement from the discharge orifice. Preferably, the ink is heated by an electrical heating rod mounted in the printing head adjacent to the cavity. Means are also provided for sensing the temperature of the ink in the cavity. The heating rod is selectively energized to maintain the ink at the preselected temperature by means of a feedback control circuit coupled with the sensing means.

Abstract: A laminar air flow passageway through which ink droplets are directed before striking a moving print medium, having a portion of the passageway contoured to expand toward the print medium for slowing a column of air passing therethrough before the column reaches the document. Air suction apertures located in the expanded portion of the passageway and near the print medium provide withdrawal of the airflow to prevent air buildup at the document interface and to maintain laminarity as the air slows. A separate embodiment includes a single air suction aperture located in the upper portion of a gently expanding air passsageway for airflow withdrawal.