Ink jet printer and start up method therefor

Claim 1

An ink jet printer for depositing ink drops on a print receiving medium, comprising: print head means having a fluid receiving reservoir and including an orifice plate defining a row of orifices through which ink from said reservoir passes to form a row of downward extending fluid filaments, means for stimulating said fluid filaments to cause each of said fluid filaments to break up into a jet drop stream, a charge electrode plate positioned beneath said print head means and to one side of said row of fluid filaments, said plate including a plurality of charge electrodes, each of said electrodes positioned adjacent a respective one of said fluid filaments and spaced therefrom by a predetermined distance, ink supply inlet means for supplying ink to said fluid receiving reservoir in a direction substantially perpendicular to said row of orifices and to said fluid filaments, said ink supply inlet means being positioned on the same side of said fluid filaments as said charge electrode plate, ink supply outlet means for removing ink from said fluid receiving reservoir in a direction substantially perpendicular to said row of orifices and to said fluid filaments, said ink supply outlet means being positioned on the side of said fluid filaments opposite said ink supply inlet means, means for selectively applying charging potentials to said plurality of charge electrodes such that drops in said jet drop streams are selectively charged, means for providing a drop deflection field through which said jet drop streams pass, such that drops in said jet drop streams are separated into catch and print trajectories, means for catching drops in said catch trajectories while permitting drops in said print trajectories to strike said print receiving medium, and fluid supply control means for controlling the application of ink to and removal of ink from said fluid reservoir, whereby fluid flow across said row of orifices from said inlet means to said outlet means is provided at start up of said printer to deflect said filaments away from said charge electrodes by a distance greater than said predetermined distance, and whereby said fluid flow across said row of orifices is terminated after start up such that said fluid filaments are thereafter spaced from said electrodes by said predetermined distance, said fluid supply control means including means for providing a sufficient back pressure within said fluid receiving reservoir during flow from said inlet means to said outlet means at start up to produce fluid flow through said orifices and formation of said fluid filaments.

Claim 13

A method of initiating operation of an ink jet printer having a print head defining a fluid reservoir and including an orifice plate defining a row of orifices, communicating with said reservoir, through which fluid from said reservoir flows to form a row of fluid filaments, said printing further having a charge plate positioned adjacent said row of fluid filaments and including a plurality of charge electrodes, each of said electrodes being associated with a respective one of said fluid filaments and spaced therefrom during operation of said printer by a predetermined distance, comprising the steps of: supplying ink to said fluid reservoir at printer start up such that the ink flows parallel to said orifice plate past said orifices in a direction substantially perpendicular to said row of orifices while maintaining sufficient fluid pressure within said fluid reservoir to produce fluid flow through said orifices and formation of said fluid filaments, thereby imparting a velocity component to the fluid filaments, deflecting said filaments away from said charge plate such that said filaments are spaced from said electrodes by a distance greater than said predetermined distance, and thereafter terminating said flow of fluid past said orifices, whereby said filaments are spaced from said electrodes by said predetermined distance.

Claim 14

A method of initiating operation of an ink jet printer having a print head defining a fluid reservoir and including an orifice plate defining a row of orifices, communicating with said reservoir, through which fluid from said reservoir flows to form a row of fluid filaments, said printing further having a charge plate positioned adjacent said row of fluid filaments and including a plurality of charge electrodes, each of said electrodes being associated with a respective one of said fluid filaments and spaced therefrom during operation of said printer by a predetermined distance, comprising the steps of: supplying ink to said fluid reservoir at printer start up such that the ink flows parallel to said orifice plate past said orifices in a direction substantially perpendicular to said row of orifices while maintaining sufficient fluid pressure within said fluid reservoir to produce fluid flow through said orifices and formation of said fluid filaments, thereby imparting a velocity component to the fluid filaments, deflecting said filaments away from said charge plate such that said filaments are spaced from said electrodes by a distance greater than said predetermined distance, and thereafter terminating said flow of fluid past said orifices, whereby said filaments are spaced from said electrodes by said predetermined distance.