| 摘要 |
A camera (18) arranged in the axis of a bottle to be tested is used to take pictures in order to determine defects in the upper end face of the mouth lip (43). A circular, coaxial light-conducting body (30) which is surrounded by a light source (28) is arranged between the lip (43) and the camera (18). It has a central viewing opening (40) with the shape of a double conical frustum (40a, 40b). The cylindrical surface of the conical frustum (40a) facing the lip forms a light exit surface (46a) for illuminating the lip (43). The angle of slope of the conical frustum (40a) is selected such that an annular optical conical frustum (52) falls onto the upper end face of the lip (43) and has in the middle thereof an angle of incidence of approximately 45 DEG . This yields a dark field illumination of the lip (43). Should a defect be present in the region of the upper end face of the lip (43), it becomes visible brightly on the dark background. Lateral defects of the lip (43) can also be determined with the aid of an additional light-conducting body (34). …<IMAGE>… |
