An optically reading type photo-sensor for reading out an information signal of a signal light with a signal reading light includes a first photoconductor (101) and a second photoconductor (102) interposed between two electrodes (104 and 105); an intermediate region (103) disposed between those two photoconductors...http://www.google.co.uk/patents/US5196702?utm_source=gb-gplus-sharePatent US5196702 - Photo-sensor and method for operating the same
