Abstract: Variations in laser output power are compensated for by increasing the on time of weaker output lasers relative to the more powerful lasers. To avoid nonlinearities where the object to be marked is a moving substrate, the on time pulses which control the lasers are centered about a single time reference point. Additionally, for high printing rates a pre-ionization technique is disclosed which is utilized to enable a laser to fire more quickly than would otherwise be possible. Pre-ionization may be used for every dot to be printed or only when a laser has not been fired during the previous printing "stroke" depending upon the stroke rate.

Abstract: Apparatus for inscribing characters or other symbols onto moving articles or substrate. The symbols or characters are defined by a matrix having a predetermined number of rows and columns. The apparatus includes a plurality of individual lasers, each dedicated to write a predetermined character row. Columns are written in sequence as the article passes the laser head. Light energy from the lasers is directed by mirrors to an exit lens which focuses the laser beams onto the articles or substrate to be marked. Separate laser mirrors provide reduction in laser beam spacing thereby facilitating a correspondingly foreshortened laser beam path. The lasers are arranged into two groups and interleaved to form the desired character row spacing without mirror overlap or shadowing.

Abstract: The invention is an ink drop catcher for use in a drop marking device such as an ink jet printer. The catcher receives drops which are not to be deposited on the recording medium. The catcher includes a convoluted passage through which the drops pass to return to the ink supply. An electrode disposed along the convoluted passage senses the current flow created by the accumulation of the charges from a series of test drops. This current flow is used by phasing circuitry to insure that the drops are correctly charged at the time they are formed.

Abstract: A valve is disclosed suitable for use in ink marking systems. The valve has an output port, a supply port, and a control port. The control port communicates with a chamber disposed above a flexible diaphragm while the output port communicates with a reservoir to be periodically supplied with fluid. The diaphragm flexes between an open position permitting the supply port to communicate with the output port and a closed position blocking such communication as a function of the pressure differential across the diaphragm created by pressure changes at the central port.

Abstract: An ink composition for use in ink jet printing to print images on a substrate, the composition being formulated to include, as the resin component, a styrene-acrylic acid copolymer having a molar ratio of styrene to acrylic acid ranging from about 1 to about 4, a soluble dye, a solvent system including a lower alkanol and a lower aliphatic ketone, and, optionally, an evaporation retardant. The composition of the invention has a pH in the range of 1 to about 7 and contains less than about 5% water for use in printing on a variety of substrates.

Abstract: A fast acting ink valve adapted to be used in conjunction with the nozzle of an ink jet printing system is disclosed. A flexible diaphragm modulates flow through a valve chamber. A spring biases the diaphragm to a sealed position to prevent flow. Ink pressure in the marking system unseals the diaphragm permitting flow. Unlike check valves, the invention has minimal pressure drop due to the location of the bias spring outside the ink flow path.

Abstract: A method and apparatus are disclosed for providing feedback control of the ink drop velocity in a drop marking system. The control system maintains essentially constant velocity of the ink drops as they pass through a deflection field which causes certain of the electrically conductive drops to be directed onto a substrate to be marked. The ink flow between two selected points is monitored by a control device to generate ink flow rate data and compared against a reference value. In the event that a flow rate deviation is sensed, appropriate action is taken to change the flow rate. Such action includes altering ink viscosity and/or ink pressure.