HP INCFollow


In most Large Format printers, loaded substrates to be printed may present a defect

called skew, in which the substrate is not aligned in the paper axis. This implies that

the substrate advance and printing directions are not perpendicular and thus the

resulting image orientation is slightly wrong. It might cause paper jams in the printer,

as well as different image quality issues derived from corrections wrongly applied.

An Optical Line Sensor is mounted on the carriage facing downwards and consists of

a light source and a densitometer. It can obtain a numeric value representing the

darkness or lightness reflected by the surface measured.

The invention is composed of two optical line sensors mounted in the printing

carriage. These sensors can measure the distance to the edge of the substrate at

two different points, which allows the printer to calculate the skew and take actions in


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