Ink-jet printer head

An ink-jet head for an ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate having a center and located at a position on said ink tank for allowing ejection of a droplet of said conductive ink;
• a pair of electrodes disposed on an inside surface of said ink tank at a position corresponding to the position of said nozzle;
• first means for applying a voltage to said pair of electrodes to cause a current having a current density to be passed through said conductive ink contained between said pair of electrodes;
• and
• second means disposed between said electrodes for increasing the current density of said current, said second means including a projection made of an electrically insulating material and disposed between said pair of electrodes, said projection having a peak sloping down toward said pair of electrodes;
• and disposed directly below the center of the said nozzle.

An ink-jet head for an ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate having a center and located at a position on said ink tank for allowing ejection of a droplet of said conductive ink;
• a pair of electrodes disposed on an inside surface of said ink tank at a position corresponding to the position of said nozzle;
• first means for applying a voltage to said pair of electrodes to cause a current having a current density to be passed through said conductive ink contained between said pair of electrodes;
• and
• second means disposed between said electrodes for increasing the current density of said current, said second means including a pair of projections made of an electrically insulating material, said projections confronting and merging with one another and having peaks sloping down toward said pair of electrodes, said peaks of said pair of projections defining a recess extending along a common longitudinal axis of said pair of electrodes, said peaks being disposed directly below the center of said nozzle and merging with each other.

An ink-jet head for an ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate having a center and located at a position and on said ink tank for allowing ejection of a droplet of said conductive ink;
• a pair of electrodes disposed on an inside surface of said ink tank at a position corresponding to the position of said nozzle;
• first means for applying a voltage to said pair of electrodes to cause a current having a current density to be passed through said conductive ink contained between said pair of electrodes;
• and
• second means disposed between said electrodes for increasing the current density of a said current, said second means including a first projection made of an electrically insulating material and disposed between said pair of electrodes, and two confronting second projections made of an electrically insulating material and projecting between said pair of electrodes from a pair of first planes, respectively, extending perpendicular to a second plane from which said first projection projects, said first projection having a peak sloping down toward said pair of electrodes, said second projections having peaks defining therebetween a recess extending above said first projection in a direction parallel to a common longitudinal axis of said pair of electrodes.

An ink-jet head for an ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate on said ink tank for allowing ejection of a droplet of said conductive ink;
• first means for providing a voltage;
• a pair of electrodes, disposed within said ink tank, electrically connected to said first means, said electrodes having end surfaces opposite each other which are responsive to the voltage from said first means to produce electric lines of force therebetween so that a current having a current density passes through the conductive ink along the electric lines of force;
• and
• second means disposed between said electrodes, said second means being geometrically oriented to have a projection including a peak which is located in alignment with said end surfaces of said pair of electrodes, said second means for causing the electric lines of force to be constricted so that the current density of said current passing through the conductive ink is increased.

An ink-jet head for and ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate located at a position said ink tank for allowing ejection of a droplet of said conductive ink;
• a pair of electrodes disposed on an inside surface of said ink tank at a position corresponding to the position of said nozzle;
• first means for applying a voltage to said pair of electrodes to cause a current having a current density to be passed through said conductive ink contained between said pair of electrodes;
• and
• second means disposed between said electrodes for increasing the current density of said current only at a preselected position defined between said pair of electrodes;
• wherein said preselected position is three-dimensionally determined.

An ink-jet head for an ink-jet printer, comprising:

• an ink tank for holding therein a conductive ink;
• a nozzle provided in a nozzle plate located at a position said ink tank for allowing ejection of a droplet of said conductive ink;
• a pair of electrodes disposed on an inside surface of said ink tank at a position corresponding to the position of said nozzle;
• first means for applying a voltage to said pair of electrodes to cause a current having a current density to be passed through said conductive ink contained between said pair of electrodes, said electrodes having confronting surfaces of equal area;
• and
• second means disposed between said electrodes for increasing the current density of said current only at a preselected position defined between said pair of electrodes.