Automatic horizontal and vertical head-to-head alignment method and sensor for an ink jet printer

A printhead alignment sensor for an ink jet printer, said sensor comprising:

• a plurality of first aligned terminals, each pair of adjacent said first terminals being separated by a corresponding substantially linear first gap;
• an ink support device configured to support ink in the first gaps between said first terminals;
• and
• an electrical measuring device configured to detect a change in an electrical parameter between said adjacent first terminals when ink is supported in at least one of the first gaps by said ink support device.

A printhead alignment sensor for an ink jet printer, said sensor comprising:

• a first terminal having a base and a plurality of tines extending therefrom;
• a second terminal disposed between two adjacent said tines of said first terminal such that said second terminal and said adjacent tines define a pair of substantially linear first gaps therebetween, and said second terminal and said base define a substantially linear second gap therebetween, said second gap being substantially perpendicular to said first gaps;
• and
• an electrical measuring device configured to detect a change in an electrical parameter between said first terminal and said second terminal when ink is in at least one of the gaps between said first terminal and said second terminal.

A method of horizontally aligning a first printhead and a second printhead in an ink jet printer, said method comprising the steps of:

• providing a substrate having a target area with a width approximately equal to a width of an ink drop;
• moving a carrier of the first printhead from a first location toward said target area;
• jetting a plurality of aligned first ink drops from the first printhead when said carrier of the first printhead is at a first jetting location, the aligned first ink drops being substantially parallel to said target area;
• sensing whether at least one of said first ink drops has been jetted onto said target area;
• returning said carrier of the first printhead to said first location;
• repeating said moving, jetting, sensing and returning steps until at least one of said first ink drops has been jetted onto said target area, said jetting steps being performed at various said first jetting locations;
• recording a first reference location of said carrier of the first printhead, said first reference location being a location of said carrier of the first printhead when it is sensed that at least one of said first ink drops has been jetted onto said target area;
• moving a carrier of the second printhead from a second location toward said target area;
• jetting a plurality of aligned second ink drops from the second printhead when said carrier of the second printhead is at a second jetting location, the aligned second ink drops being substantially parallel to said target area;
• sensing whether at least one of said second ink drops has been jetted onto said target area;
• returning said carrier of the second printhead to said second location;
• repeating said moving, jetting, sensing and returning steps until at least one of said second ink drops has been jetted onto said target area, said jetting steps being performed at various said second jetting locations;
• recording a second reference location of said carrier of the second printhead, said second reference location being a location of said carrier of the second printhead when it is sensed that at least one of said second ink drops has been jetted onto said target area;
• and
• calculating at least one offset based upon said first reference location and said second reference location.

A method of vertically aligning a first printhead and a second printhead in an ink jet printer, said method comprising the steps of:

• providing a substrate having a target area with a height approximately equal to a width of an ink drop;
• jetting a plurality of aligned first ink drops from the first printhead with a nozzle of the first printhead which is at a first y-direction coordinate such that the aligned first ink drops are substantially parallel to said target area and to a scan direction of the first printhead;
• sensing whether at least one of said first ink drops has been jetted onto said target area;
• repeating said jetting and sensing steps until at least one of said first ink drops has been jetted onto said target area, said jetting steps being performed with nozzles at various said first y-direction coordinates;
• recording a first reference nozzle position of the first printhead, said first reference nozzle position being a position of a nozzle of the first printhead when it is sensed that at least one of said first ink drops has been jetted onto said target area;
• jetting a plurality of aligned second ink drops from the second printhead with a nozzle of the second printhead which is at a second y-direction coordinate such that the aligned second ink drops are substantially parallel to said target area and to a scan direction of the second printhead;
• sensing whether at least one of said second ink drops has been jetted onto said target area;
• repeating said jetting and sensing steps until at least one of said second ink drops has been jetted onto said target area, said jetting steps being performed at various said second y-direction coordinates;
• recording a second reference nozzle position of the second printhead, said second reference nozzle position being a position of a nozzle of the second printhead when it is sensed that at least one of said second ink drops has been jetted onto said target area;
• and
• calculating at least one offset based upon said first reference nozzle position and said second reference nozzle position.