Patent ID: 8013886
Filing Date: 2011-09-06
Classification: B41J,G11B

Abstract:
1. A device for scanning a medium and scribing a visible label on the medium, the medium having a label side provided with a radiation sensitive layer for creating the visible label by scribing traces of dots via a beam of radiation, the device comprising: a head or providing the beam of radiation for, in a label mode, generating a scribing spot on the radiation sensitive layer for scribing the visible label, and for generating at least one detector signal in dependence of radiation reflected from the medium; a control unit comprising label control means for controlling the scribing in dependence of label data; and focus means for generating a focus control signal for focusing the scribing spot, the focus means being arranged for detecting a focus error by including a focus excitation signal in the focus control signal and detecting a deviation in the at least one detector signal in dependence of the focus excitation signal, the label control means being arranged for controlling the focus means in dependence on the label data to detect the focus error during said scribing and without interrupting said scribing, wherein the focus excitation signal has a first amplitude during a learning process while not scribing and a second amplitude during said scribing, the second amplitude being substantially smaller than the first amplitude.