Patent ID: 6147356
Filing Date: 2000-11-14
Classification: H01L

Abstract:
An arrangement for the detection of disk-shaped objects in a cassette having a plurality of shelves, said arrangement comprising:an illumination unit whose light is directed onto reflecting edge areas of the objects which are visible at openings of the shelves of the cassette;at least one optical system for the transmission of light which, proceeding from the illumination unit, has been reflected in at least one edge area;a sensor unit having at least one linear array of light-sensitive sensor elements which is oriented vertical to the direction of the shelves and to the direction of the disk-shaped objects and which converts the light reflected by the edge areas of the objects into electrical signals;an evaluating unit for determining the presence and the position of objects in the shelves of the cassette;said illumination unit having at least two linearly elongated rows of light sources which are arranged parallel to a family of planes predetermined by the shelves and objects and which lie in a surface parallel to the edge areas to be detected;said optical system being an objective which is arranged between the parallel linear light sources and by which a plurality of shelves is imaged simultaneously on the sensor unit; andthe array of sensor elements allowing the reading out of at least portions of an edge area of the objects which is elongated transversely to such an extent that, when imaged in the sensor plane, an irregularity present in the edge area of the object is always less than the read out portions of the elongated edge area.