Fluid jet printer and method of operation

A jet printer for printing on a print receiving medium, comprising:

• print head means for generating a plurality of jet drop streams arranged in a row and directed at said print receiving medium, a plurality of fluid filaments emerging from said print head and breaking up into said jet drop streams,
• drop charging means, including a notched charge electrode plate in which a plurality of charge electrodes are defined by electrically conductive coatings within notches spaced along one edge of said plate, said drop charging means permitting selective electrical charging of drops in each of the jet drop streams when electrical charging potentials are selectively applied to said charge electrodes and said charge electrodes partially surround corresponding fluid filaments,
• drop control means for deflecting said drops in dependence upon the electrical charges carried thereby and for catching at least some of said drops,
• mounting means for pivotally supporting said charging means such that said charge electrode plate may be pivoted between an operating position in which each charge electrode partially surrounds a corresponding one of said fluid filaments emerging from said print head, and a retracted position in which said charge electrodes are retracted from said fluid filaments, said mounting means providing for pivoting said charge electrode plate about an axis parallel to each of said streams and in line with said row of jet drop streams, and
• means for pivoting said charge electrode plate into said operating position after start-up of said print head means and for pivoting said charge electrode plate into said retracted position prior to shutdown of said print head means, whereby contamination of said charging means by jet drops generated unstably at start-up and shutdown is prevented.