Charge compensation network for ink jet printer

In an ink jet printer of the type wherein a stream of ink drops is projected through a means for applying a charge to individual drops responsive to video signals indicative of a desired printout, said stream of ink drops thereafter passing through an electric field to be deflected in accordance with the charges on said drops, thereafter terminating on a receiving substrate,

• means for compensating the charge being applied to predetermined drops in a stream of ink drops for the effects of the electric fields established by charged drops as well as for aerodynamic effects comprising,
• means for stimulating the charge-no charge pattern which a stream of drops will have after passing through said means for applying a charge each time one of the drops in said stream is passing through said means for applying a charge, including
• means for establishing a representative signal representing each drop to be charged by said charging means,
• shift register means for establishing first, second, third and fourth representative signal inpsection locations for inspecting representative signals respectively at two intervals before each drop passes through said means for applying a charge, at one interval before a drop passes through said means for applying a charge, during and at one interval after the drop represented is passing through said means for applying a charge to individual drops, and
• means for passing said representative signals through said representative signal inspection locations in synchronism with drops passing through said means for applying an individual charge,
• logic means solely responsive to a predetermined pattern of representative signals in said signal inspection locations in said shift register means, for producing a modification signal, and
• means responsive to said modification signal for modifying the charge being applied to said predetermined drop by said means for applying a charge to compensate for aerodynamic effects or for the effects of the charges on other ink drops.

In an ink jet printer of the type wherein a stream of ink drops is projected through a means for applying a charge to individual drops responsive to video signals indicative of a desired printout, said stream of ink drops thereafter passing through an electric field to be deflected in accordance with the charges on said drops, thereafter terminating on a receiving substrate,

• means for generating a train of signals simulating the charge and no charge states of drops in a stream of drops which would exist before drops pass through said means for charging and which exists during and after passing through said means for charging,
• first means for sensing solely from said train of signals when the first drop in a stream of charged drops is passing through said means for charging and producing a first modifying signal responsive thereto,
• first means responsive to said first modifying signal for modifying the charge applied by said means for charging to the first drop in a stream to compensate for the effects thereon of the charges on the succeeding drops in said stream,
• second means for sensing solely from said train of signals when the last drop in said stream of charged drops is passing through said means for charging and producing a second modifying signal responsive thereto,
• second means responsive to said second modifying signal for modifying the charge applied by said means for charging to the last drop in said stream to compensate for the effects thereon of the charges on the other drops in said stream,
• third means for sensing solely from said train of signals when the next to the last drop in said stream of drops is passing through said means for charging and producing a third modifying signal responsive thereto, and
• third means responsive to said third modifying signal for modifying the charge applied by said means for charging to said next to the last drop in said stream to compensate for the effects of the charges on the other drops of said stream thereon.