Abstract: According to certain aspects of an embodiment of the present invention, a deflection electrode assembly is provided for use in a continuous ink jet printer of the type which projects a stream of ink drops toward a substrate and controls placement of the ink drops on the substrate by selectively charging the individual ink drops and passing the charged ink drops through an electric (deflection) field created by the deflection electrode assembly. The deflection electrode assembly includes a high voltage deflection electrode and a low voltage deflection electrode positioned on opposite sides of the ink drop stream. A dielectric insulating member is mounted on at least one of the deflection electrodes. The insulating member include a longitudinal opening which exposes the deflection electrode along the path of the ink jet stream, thereby virtually eliminating the tendency for accumulated ink to decrease the strength of the deflection field.

Abstract: According to certain aspects of an embodiment of the present invention, a deflection electrode assembly is provided for use in a continuous ink jet printer of the type which projects a stream of ink drops toward a substrate and controls placement of the ink drops on the substrate by selectively charging the individual ink drops and passing the charged ink drops through an electric (deflection) field created by the deflection electrode assembly. The deflection electrode assembly includes a high voltage deflection electrode and a low voltage deflection electrode positioned on opposite sides of the ink drop stream. A dielectric insulating member is mounted on at least one of the deflection electrodes. The insulating member include a longitudinal opening which exposes the deflection electrode along the path of the ink jet stream, thereby virtually eliminating the tendency for accumulated ink to decrease the strength of the deflection field.

Abstract: A clean-in-place system for use in an ink jet printhead has a compartment and an end plate with a slot therein to permit ink drops to be projected from the compartment onto a substrate to be marked. For cleaning purposes, a shutter is disposed adjacent the slot to seal it. Thereafter, the pump floods the compartment with ink solvent from a solvent reservoir. The solvent may be agitated by air or a mechanical device. Thereafter, a drain line is used to remove the solvent from the compartment. The pneumatic shutter is reopened after the solvent is withdrawn to enhance the drying of the components. The shutter may consist of an inflatable member and a pump for supplying compressed air to the inflatable member to inflate and deflate it.

Abstract: Flight time of a stream of ink drops is measured and compared against a set point to determine variations therefrom. Variations due to changes in the ink composition are compensated for by adding or withholding solvent in proportion to the detected change. Changes due to variations in nozzle drive voltage result in the computation and use of a new flight time set point value, if necessary to avoid erroneous corrective action.

Abstract: The printhead of an ink jet printer includes an electrically conductive plastic chassis and charging electrode. The plastic chassis can be constructed of plastic resins such as polyester, nylon, acetal, and polyphenylene sulphide imbedded with electrically conductive fibers such as carbon and stainless steel. The fibers can be coated with nickel to improve the shielding characteristics of the material.

Abstract: A variable orientation ink catcher for use with ink jet printing equipment receives unused ink drops. The drops are returned to the printing system for reuse. The catcher includes an arcuate receiving portion offset from an outlet port. Caught ink flows by gravity from the receiving portion via a reservoir to the outlet port through a wide range of angular orientations.

Abstract: A drop deflection device suitable for use in a drop marking system employs an electret. Electrically conductive marking drops such as inks are given an electrical charge. The drops pass between a pair of deflections plates at least one of which is formed by an electret (a dielectric material which has been subjected to corona discharge to create a relatively permanent electrically charged material body). Depending upon the presence or absence of a charge on a particular drop, it will be deflected by the field between the plates on to a substrate for marking. If uncharged, the drops continue to a collection device which returns them to the ink reservoir.

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: 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.

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 system for printing with ink droplets each having a known quantity of ink which system has a hydraulic portion including a main ink supply, a supplemental ink supply and a recirculating droplet generating print head and an electronic portion which includes a character generator for electrically characterizing each of the droplets so that they are directed either to a print target or to a dump and a monitoring means for identifying the droplets assigned to strike the print target and controls in the hydraulic portion for permitting a metered additional quantity of ink, depending on the number of print target directed droplets counted, to flow from the supplemental ink supply to the main ink supply, thus, allowing use of a standard ink formulation in the supplemental ink supply.

Abstract: In an ink jet printing system, there is provided an arrangement whereby the ink, which is not used in printing, may be returned to the reservoir from which it was withdrawn, together with fresh ink, in a manner so that ink pressure fluctuations, together with shutdowns for filling the reservoir are avoided.