Abstract: An ink supply system for supplying ink through the print head of an ink jet printer includes a pump arrangement supplying ink to the print head from a supply tank and, further, plural ink return lines connected between the pump outlet and the pump inlet. Each of the ink return lines includes a flow restriction, with the flow restriction in each line providing a fluid flow impedance which differs from the impedances provided by the other flow restrictions. A valve arrangement controls the connection of the pump outlet to a selected one of the ink return lines, such that the flow rate of ink through the ink supply line to the print head is effectively controlled.

Abstract: An ink jet printing apparatus for printing addresses on documents being transported along an independently operated conveyor. The printing apparatus includes a control console, a printing arm telescopically received within the console, and an ink jet printing head mounted on a carriage which is vertically movable within the printing arm. A tachometer wheel is mounted on the printing carriage for contacting a document being transported past the printing head and generating a tachometer signal in response thereto. A programmed microprocessor generates printing control signals in synchronism with the tachometer signal.

Abstract: An ink jet printing apparatus for printing addresses on documents being transported along an independently operated conveyor. The printing apparatus includes a control console, a printing arm telescopically received within the console, and an ink jet printing head mounted on a carriage which is vertically movable within the printing arm. A tachometer wheel is mounted on the printing carriage for contacting a document being transported past the printing head and generating a tachometer signal in response thereto. A programmed microprocessor generates printing control signals in synchronism with the tachometer signal.