Use of sequential firing to compensate for drop misplacement due to curved platen

A method of actuating an ink jet printhead to form characters on a recording medium contained on a curved surface, said printhead including a center and a plurality of nozzles arranged transverse said center in at least one line having opposing ends and being capable of emitting ink drops at a velocity, a distance between said ends defining a printhead length, a projection of said line being substantially perpendicular to a longitudinal axis of the curved surface, said method comprising the steps of:

• sequentially actuating the nozzles, starting with nozzles located furthest from said surface and proceeding to actuate nozzles located substantially progressively closer to the surface until the actuation of all nozzles has been performed, wherein the printhead is located relative to the surface such that a central portion of the line of nozzles is closest to the surface, said sequential actuation starting with nozzles located on each end of said line of nozzles and proceeding substantially inwardly until the actuation of all nozzles has been performed, wherein a constant time, t, between each successive actuation of nozzles is determined approximately by the formula:
• t=(n/N)(h.sup.2 2rv.sub.d)
• where
• h=half the printhead length;
• r=radius of the curved surface;
• v.sub.d =the velocity of the ink drops emitted from the nozzles;
• n=number of nozzles fired at one time;
• and
• N=total number of nozzles in the line of nozzles.

A method of actuating an ink jet printhead to form characters on a recording medium contained on a curved surface, said printhead including a center and a plurality of nozzles arranged transverse said center in at least one line having opposing ends and being capable of emitting ink drops at a velocity, a distance between said ends defining a printhead length, a projection of said line being substantially perpendicular to a longitudinal axis of the curved surface, said method comprising the steps of:

• sequentially actuating the nozzles, starting with nozzles located furthest from said surface and proceeding to actuate nozzles located substantially progressively closer to the surface until the actuation of all nozzles has been performed, wherein the printhead is located relative to the surface such that a central portion of the line of nozzles is closest to the surface, said sequential actuation starting with nozzles located on each end of said line of nozzles and proceeding substantially inwardly until the actuation of all nozzles has been performed, wherein a time, t.sub.m, at which each nozzle is actuated is determined by the formula:
• t.sub.m [tm]=(h.sup.2 -y.sup.2)/2rv.sub.d
• where
• t.sub.m =the time when an mth nozzle is actuated with the time when the nozzles located on each end of said line of nozzles are actuated corresponding to a time, t.sub.o ;
• h=half the printhead length;
• y=distance above or below the printhead center;
• r=radius of the curved surface;
• and
• v.sub.d =the velocity of the drops emitted from the nozzles.

An ink jet printer which compensates for systematic variation in distances between printhead nozzles and a receiving medium comprising:

• a curved surface;
• a printhead including a plurality of nozzles arranged in at least one line having opposing ends and being capable of emitting ink drops at a velocity, a distance between said ends defining a printhead length, a projection of said line being substantially perpendicular to a longitudinal axis of the curved surface, and
• means for sequentially actuating said nozzles, starting with nozzles located furthest from said curved surface and proceeding to actuate nozzles located substantially progressively closer to the surface until actuation of all nozzles has been performed;
• wherein said means for sequentially actuating actuates said nozzles at successive intervals, a length of each of said successive intervals being at least as long as a pulse width of an actuation signal applied to said nozzles so that successively actuated nozzles are not actuated at the same time.

An ink jet printer which compensates for systematic variation in distances between printhead nozzles and a receiving medium comprising:

• a curved surface;
• a printhead including a center and a plurality of nozzles arranged transverse said center in at least one line having opposing ends and being capable of emitting ink drops at a velocity, a distance between said ends defining a printhead length, a projection of said line being substantially perpendicular to a longitudinal axis of the curved surface, and
• means for sequentially actuating said nozzles, starting with nozzles located furthest from said curved surface and proceeding to actuate nozzles located substantially progressively closer to the surface until actuation of all nozzles has been performed, wherein said printhead is located relative to the curved surface such that a central portion of the line of nozzles is closest to the surface and said means for sequentially actuating the nozzles starts with nozzles located on each end of said line of nozzles and proceeds substantially inwardly until the actuation of all nozzles has been performed, and a constant time interval, t, between each successive actuation of nozzles is determined approximately by the formula;
• t=(n/N)(h.sup.2 /wrv.sub.d)
• where
• h=half the printhead length;
• r=radius of the curved surface;
• v.sub.d =the velocity of the ink drops emitted from the nozzles;
• n=number of nozzles fired at one time;
• and
• N=total number of nozzles in the line of nozzles.

An ink jet printer which compensates for systematic variation in distances between printhead nozzles and a receiving medium comprising:

• a curved surface;
• a printhead including a center and a plurality of nozzles arranged transverse said center in at least one line having opposing ends and being capable of emitting ink drops at a velocity, a distance between said ends defining a printhead length, a projection of said line being substantially perpendicular to a longitudinal axis of the curved surface, and
• means for sequentially actuating said nozzles, starting with nozzles located furthest from said curved surface and proceeding to actuate nozzles located substantially progressively closer to the surface until actuation of all nozzles has been performed, wherein said printhead is located relative to the curved surface such that a central portion of the line of nozzles is closest to a time, the surface and said means for sequentially actuating the nozzles starts with nozzles located on each end of said line of nozzles and proceeds substantially inwardly until the actuation of all nozzles has been performed, and said means for actuating actuates said nozzles at a time, t.sub.m, according to the formula:
• [tm=(h.sup.2 -y.sup.2)/2rv.sub.d ]t.sub.m =(h.sup.2 -y.sup.2)/2rv.sub.d
• where
• t.sub.m =the time when an mth nozzle is actuated with the time when the nozzles located on each end of said line of nozzles are actuated corresponding to a time, t.sub.o ;
• h=half the printhead length;
• y=distance above or below the printhead center;
• r=radius of the curved surface;
• and
• v.sub.d =the velocity of the drops emitted from the nozzles.