Patent ID: 6469729
Filing Date: 2002-10-22
Classification: B23K,B65C,G06K

Abstract:
A device for marking a relatively moving substrate by scanning a laser beam along an optical path generally defining a length that terminates at the substrate, the length of the optical path varying during marking, the marking device comprising:a laser source for producing the laser beam; an objective lens having a surface disposed in the optical path to direct the laser beam onto the substrate; a scanner in the optical path for scanning the laser beam across said surface of said objective lens, so that said objective lens produces a variable image distance across said surface of said objective lens; and a controller for synchronizing the scanner to the motion of the substrate, said controller including an encoder for determining a first component of movement of the substrate and a memory having stored therein data representing a second component of movement of the substrate, said controller combining said first and second components for driving said scanner, said second component corresponding to variation in said length of said optical path due to said substrate changing position closer to, or farther away from, said objective lens along said optical path, wherein said variable image distance closely conforms to the variation in the length of said optical path, whereby the laser beam is maintained at a desired marking distance as it is scanned over the substrate.