Patent ID: 7886977
Filing Date: 2011-02-15
Classification: G06K

Abstract:
1. Optical sensor for detecting a code on a substrate which, in use, moves with respect to the optical sensor, comprising an optical detector including imaging optics for imaging the substrate onto the optical detector, the optical detector continuously or repeatedly determining a value of a reflective property of the substrate, wherein the optical detector, in use, views the substrate along an optical axis, an alignment light source disposed adjacent to the optical detector and imaged onto the substrate by the imaging optics such that the substrate is focused at the optical detector by using a projection of the alignment light source directed along the optical axis onto the substrate, a code analyzer for determining the detected code on the basis of a variation of the value of the determined reflective property in time, a first illumination source for illuminating the substrate along the optical axis of the optical detector, a second illumination source for illuminating the substrate in a direction at a non-zero angle with respect to the optical axis, and a control unit having a first operational mode wherein the first illumination source is switched on and the second illumination source is switched off, and having a second operational mode wherein the first illumination source is switched off and the second illumination source is switched on, and having a third operational mode wherein the first illumination source and the second illumination source are switched off and the code analyzer is calibrated by determining an amount of ambient light present, wherein the control unit is arranged for cyclically being in the first, second or third operational mode.