| 摘要 |
A device for detecting foreign substances, such as, e.g., moisture, dirt or snow, present on a disc, has an optoelectronic sensor (2). The latter has two light sources (e.g. 3), each of which is assigned an optoreceiver (e.g. 8). The spatial arrangement of the components is such that one optoreceiver (8) receives totally reflected light in the case of a dry disc (1), so that the absence of a signal is an index for water on the disc (1). The other optoreceiver records the light reflected diffusely by the dust on the disc (1), and therefore provides information about contamination of the disc (1). The light sources (e.g. 3) are assigned reference beam optoreceivers (e.g. 9), so that interference can be eliminated. <IMAGE>
|
