Alignment apparatus

Apparatus for aligning with respect to a known reference position an object disposed in the field of view of a television camera on a carrier adjustable in X and Y axial directions, the television camera scanning a surface of the object and a peripheral area surrounding the object in a line raster and generating electrical video signals which correspond to an image of the scanned area, comprising digitizing means for which receiving the video signals and forming therefrom digital video signals of two signal levels which for the video signals originating from the object have predominantly a first signal level and for the video signals originating from the peripheral area have the second level, analyzing means (a) for analyzing the digital video signals in two sets of data windows, each set associated with an individual one of the X and Y axial direction and in each set, the data windows corresponding to separate regions of the video image having in the associated axial direction predetermined distances from each other and different distances from an associated edge of the image of the object, and (b) for responding to the appearance of digital video signals of the first signal level in each data window and furnishing output signals for each data window set depending on the number of data windows counted in uninterrupted sequence in a predetermined sense in the associated axial direction, and during which the proportion of digital video signals of the first signal level exceeds a predetermined minimum value, wherein a single data window set is provided for each axial direction, and in that and wherein each data window set the number of data windows counted in uninterrupted sequence in said predetermined sense in the respective axial direction and having a proportion of digital video signals of the first signal level exceeding said predetermined minimum value is equal to a predetermined number (N) different from zero when said object is aligned with respect to said reference position.