Patent ID: 9533370
Date: 2017-01-03
CPC Classifications: B23K,B41J,B41M

Claim:
1. A method for laser marking an anodized metal surface with a desired colour, which method comprises: providing a laser for emitting a laser beam comprising laser pulses having a pulse energy, a pulse width, and a pulse repetition frequency; providing a seamier comprising a first mirror for scanning the laser beam in a first direction, and a second mirror for scanning the laser beam in a second direction; providing a lens for focussing the laser beam from the laser onto the anodized metal surface to form a spot having a spot diameter and a pulse fluence; providing a controller for controlling the scanner with a control signal; marking a plurality of lines separated by a hatch distance on the anodized metal surface to form a desired mark by scanning the scanner while pulsing the laser; and selecting a scan speed, the pulse repetition frequency, and the spot diameter such that the separation between consecutive spots during each scan of the scanner is at least one quarter of the spot diameter; the method being characterized by overwriting each line more than once; the colour being given by the spot to spot separation, the hatch distance, the pulse fluence, the pulse width, and the number of times each line is written; and selecting the spot to spot separation, the hatch distance, the pulse fluence, the pulse width, and the number of times each line is written to form the desired colour.