| 摘要 |
A method for detecting different types, in particular of glazed and unglazed photographic slides during projection is proposed, the intention being that the information which is obtained will be used, for example, for correcting the setting of a focusing device or for controlling other processes during projection. For this purpose, it is proposed to provide marks, for example knobs, windows, reflectors, magnetic marks or the like, on the frame of the photographic slide and with the aid of these marks to produce signals by means of detectors corresponding to the type of marks. In accordance with the preferred embodiment of the method, the image window of the photographic slide itself serves as marking field which is irradiated with IR light. The device which is necessary for this consists of an IR projector and a detector which are arranged in such a way that the detection can be performed whilst the photographic slide is located in the position ready for projection. <IMAGE>
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