Test device

A device for optically checking features of elongate, rotationally symmetrical objects that are preforms, comprising

• an inclined plate with an upper edge and a lower edge, each of the upper edge and the lower edge extending across a width of the plate, wherein a slope of the inclined plate is arranged in such a way that the objects move on a surface of the inclined plate from the upper edge to the lower edge owing to the gravitational force acting on them;
• ejection fingers disposed along the lower edge of the inclined plate and arranged parallel to one another, side by side, so as to be pivotable out of a corresponding initial position into an ejection position,
• wherein, in the initial position, surfaces of each of the ejection fingers enclose an angle of at least 180° with the surface of the inclined plate;
• each ejection finger of the ejection fingers includes a respective drive to pivot the each ejection finger of the ejection fingers between the initial position and the ejection position, wherein the angle enclosed between the surface of the inclined plate and the surface of the ejection fingers in the ejection position is less than 180°;
• a plurality of image recording units directed at the inclined plate, wherein the viewing angles of the plurality of image recording units cover the inclined plate at least over the entire width thereof, and each of the plurality of image recording units is configured to synchronously record, at different points in time with a corresponding recording frequency in a range from 50 Hz to 100 Hz, a plurality of digital images of the objects moving on the inclined plate;
• and
• a processing unit programmed to recognize all completely imaged objects in the digital images synchronously recorded at the different points in time, to check at least on feature of each recognized object by comparison with a reference object, to track a movement of each recognized object, and to perform a calculation, for the each recognized object, of a point in time and a rotational position when the each recognized object will reach a position in the region of the ejection fingers, wherein the drive of one or more of the ejection fingers is selectively actuated in accordance with this calculation and the result of the checking of the at least one feature to eject the recognized object.