US 2001/0040599 A1Published application

Easy to make printer and process for embodiment

AssigneeImaje S.A.

InventorAlain Dunand

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Abstract

Process for compensation of mechanical defects in an ink jet printer in which the ink viscosity, the jet velocity, the distance at which the ink jet is broken into droplets and the phase are independently servocontrolled to respect set values, process according to which the droplet arrival position is compared with a reference position, and mechanical defects are compensated by varying the electrical charge on the droplets. The invention also relates to a printer equipped with checking and servocontrol means so that compensation according to the process can be applied. The mechanical assembly of the printer will thus be simplified.

Claims9

Dependent claims

Process for compensation of mechanical defects in an ink jet printer by adjusting the arrival position on a substrate (27) of electrically charged ink droplets in an adjustable manner using charge electrodes (20), the droplets originating from a print head (25) and the trajectories of the droplets being modifiable by deviation electrodes (23, 24) between N positions, between a first position X1 and a last position XN and with N-2 intermediate positions, the N positions defining a frame in the form of a straight line segment approximately parallel to an X direction of the substrate (27), the process being characterized in that the following parameters are servocontrolled at all times during operation of the printer:

an ink viscosity value that remains within a predetermined tolerance as a function of its temperature, by adding solvent or ink with a higher concentration of coloring agents,
a jet velocity by acting on the ink supply pressure,
a distance at which the jet is broken into droplets by acting on an adjustable parameter to maintain a predetermined breaking distance,
a phase difference between instants at which electrical droplet charge pulses are applied and instants at which droplet formation pulses are applied by action on a timer circuit,
and in that the following steps take place during a phase prior to the print phases:
a) a pattern is printed,
b) the said printed pattern is compared with a reference pattern to deduce an algebraic difference ΔXi between a real observed position and a corresponding nominal position, for the said print head and for an integer number a of positions, where a is greater than or equal to 2 and less than or equal to N, for each of the chosen a position, where i varies from 1 to a,
c) a static translation error θ is determined as being the difference between the center of gravity of the a actual observed positions and the center of gravity of the corresponding a nominal positions,
d) for each of the a observed droplet positions, a position error δI is observed between the real position of each droplet corrected by the translation error, and the nominal position of each droplet,
e) the value θ of the static translation error and the values δI of the droplet position errors from their initial nominal positions, are memorized,
then, in each phase in which a pattern is printed defined by a set D of numeric data,
a correction value to the nominal voltage is determined for each droplet to give a corrected value to be applied to the means of charging droplets directed towards the substrate (27), this calculation taking account of memorized values of static translation and position errors, the data extracted from the set D of numeric data defining the pattern to be printed, and row j, where j is between 1 and N, of the nominal target print position.

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Dependencies are inferred from the claim text.

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Abstract

an ink viscosity value that remains within a predetermined tolerance as a function of its temperature, by adding solvent or ink with a higher concentration of coloring agents,
a jet velocity by acting on the ink supply pressure,
a distance at which the jet is broken into droplets by acting on an adjustable parameter to maintain a predetermined breaking distance,
a phase difference between instants at which electrical droplet charge pulses are applied and instants at which droplet formation pulses are applied by action on a timer circuit,
and in that the following steps take place during a phase prior to the print phases:
a) a pattern is printed,
b) the said printed pattern is compared with a reference pattern to deduce an algebraic difference ΔXi between a real observed position and a corresponding nominal position, for the said print head and for an integer number a of positions, where a is greater than or equal to 2 and less than or equal to N, for each of the chosen a position, where i varies from 1 to a,
c) a static translation error θ is determined as being the difference between the center of gravity of the a actual observed positions and the center of gravity of the corresponding a nominal positions,
d) for each of the a observed droplet positions, a position error δI is observed between the real position of each droplet corrected by the translation error, and the nominal position of each droplet,
e) the value θ of the static translation error and the values δI of the droplet position errors from their initial nominal positions, are memorized,
then, in each phase in which a pattern is printed defined by a set D of numeric data,
a correction value to the nominal voltage is determined for each droplet to give a corrected value to be applied to the means of charging droplets directed towards the substrate (27), this calculation taking account of memorized values of static translation and position errors, the data extracted from the set D of numeric data defining the pattern to be printed, and row j, where j is between 1 and N, of the nominal target print position.

9 more elements