INFRARØD TILSTEDEVÆRELSESDETEKTOR TIL DETEKTERING AF TILSTEDEVÆRELSEN AF EN GENSTAND I ET OVERVÅGNINGSOMRÅDE

摘要

The present invention relates to a detection device and a method for detecting a presence of an object in a surveillance area. The device comprises at least one infrared radiation sensing element each adapted for generating a sensor signal related to a quantity of infrared radiation received from within the surveillance area by the infrared radiation sensing element, a processing unit and an output means for outputting a determined presence of the object and/or a property derived therefrom. The processing unit is adapted for: obtaining the at least one sensor signal; generating at least one contrast value by comparing the at least one sensor signal to at least one reference value; determining the presence of the object by evaluating a condition on said at least one contrast value; and adjusting the at least one reference value such that negative feedback is applied to the at least one contrast value.