Method and circuit for monitoring the illumination condition for sequentially illuminated radiation detectors

摘要

The invention involves checking of the illumination condition of sequentially illuminated radiation detectors, primarily such detectors as function in circuits for prevention of personal injury. The illumination condition of a detector 1 and that of the closest illuminated detector 1' in time is checked by feeding the output signals A, D of the detectors each to their own NOR gate 3, 7, whose respective second input receives a signal C coming from a control circuit 5. The output signal of one gate is fed via an inverter 9 to one input of a third NOR gate 8, whose second input directly receives the output signal from the second gate 7. This carries out the logical function , where Y is the output signal of the third gate, which is fed to an input of a multiple-input NOR gate 10. During the next clock pulse from the control circuit 5, the next pair of detectors are investigated. The output signal Z of the multiple-input NOR gate 10 gives a direct indication of correct detector function and is used for sending an alarm or controlling a particular appropriate machine.