Method and device for detecting foreign matter in a moving, solid, elongated test object

摘要

The method involves receiving an electrostatic signal by a sensor (2) from a test object (9), where the electrostatic signal is utilized for detecting a foreign matter e.g. polypropylene. The electrostatic signal is received from such excess charges that were already present on the test object. Both the electrostatic signal and another signal e.g. capacitive or optical signal, are utilized for detecting the foreign matter. Independent claims are also included for the following: (1) a device for detecting foreign matter in a moving solid elongated test object (2) utilization of sensor for receiving an electrostatic signal for detecting foreign matter in the moving solid elongated test object.