Patent ID: 6912303

Claim:
A method for recognizing a deterioration in the operating performance of an apparatus which checks a large number of empty bottles of the same type made of transparent material for freedom from defects and the absence of foreign bodies by scanning an image of each empty bottle pointwise by means of a recognition apparatus, generating a feature signal for each empty bottle that is based on the number of light-dark and dark-light transitions, and comparing the feature signal with a threshold value, the empty bottles being guided in a stream through the checking apparatus; the method comprising the steps of: entering a reference value in the checking apparatus, the reference value being the feature signal of a test bottle when the checking apparatus operates correctly; conducting the test bottle to the checking apparatus after number of empty bottles together with the stream of the empty bottles, the test bottle being marked so that it is recognizable as such by the checking apparatus; checking the feature signal of the test bottle to determine the deviation of the feature signal of the test bottle from the reference value; and generating a signal indicating a possible deterioration in the operating performance of the checking apparatus, the signal depending of the deviation of the feature signal of the test bottle from the reference value.