| 摘要 |
1502349 Optical surveillance ERNST LEITZ WETZLAR GmbH 6 May 1975 [27 May 1974] 18903/75 Heading G1A To enable an area e.g. a zebra-crossing complex, a lift entrance Fig. 7 (not shown) or a bank Fig. 8 (not shown) to be optically monitored for the presence of unwanted or unauthorized persons &c., one or more optical correlators are provided, Fig. 6 in which different pupil halves of a viewing lens 1 are analyzed by respective detectors 4a, 4b or 5a, 5b, with the pair of detectors 4a, 4b and 5a, 5b being alternately used by means of beam switching and segmenting prism grating 2 oscillated by mover 7. The outputs of corresponding detectors are differentially cross-connected to give a resultant signal which after phase and amplitude analysis provides a servo-signal for so controlling the mover 7 that the signal becomes zero for the viewed scene. The presence of a person in the scene upsets the analysis and gives an alarm characteristic to the signal. In monitoring a zebra-crossing complex Fig. 1, three such correlators are used, e.g. 11, 12, 13 on a post 14 for monitoring respective areas 11a, 12a, b, c, and the adjacent crossing. A further correlator, (15), Fig. 3 (not shown) may be added to view an area further along the road. This correlator may have filters to particularly detect police cars &c. having blue flashing lights. |
