| 摘要 |
A method for making laser engravings on a web (10) of paper, comprising the steps of prearranging a paper web (10) conveying means (86) configured for conveying said web in a predetermined direction; defining a working area (12) along a path of said web (10); prearranging an emitter (14) of laser pulses (15,15', 16) that have a power set to form engravings on said web (10); prearranging a movable pointing means, comprising a reflection means (22,23) and of focus means (33), arranged to send of said laser pulses (15,15', 16) to said working area (12); selecting an engraving pattern (20) to be engraved on said web (10) by said laser pulses (15,16) emitted as pulse packets in quick succession, said pattern associated with a first function (31) defined in said working area (12) with respect to a first reference (11) that is integral to said web (10); calculating an instruction file (24) containing pointing instructions for operating said pointing means (22,23,33) in such a way that a predetermined position of said movable pointing means (22,23,33) corresponds to each pulse packet, a predetermined position of said points on said working area (12) corresponding to said predetermined position of the movable pointing means; selecting an emission power (W) of said emitter of laser pulses (14); emitting laser pulses (14) through said emission power (W) by said emitter (14); operating said movable pointing means (22,23,33) according to said instruction file, so that said movable pointing means (22,23,33) sequentially reaches each predetermined position by continuously changing the direction of said laser pulses (15,16) in said working area (12) reproducing said pattern (20) on said web (10); wherein said step of computing an instruction file (24) provides a transform of said first function (31) from said reference system (11) that is integral to said web, (10) into a second reference system (13) that is integral to said emitter (14), wherein a second transformed function (32) is obtained, by said transform, which is defined in said working area (12), and said instructions of said instruction file (24) operate said pointing means (22,23,33) in such a way that said laser pulses (16) describe said transformed function (32) with respect to said second reference system (13), in said working area (12), such that said packets of laser pulses reach said web (10), and engrave said pattern on said web as if said web were motionless. |
