System for detecting the operating state of television and broadcast sets or the like, programme selector circuit and detection device for this and television set equipped for this purpose

摘要

A system (8) for detecting the operating state of television sets exhibits a central device (22) which outputs identification signals (28) which pass into detection devices (40). Each detection device (40) is associated with a television set (14) and is able to detect the operating state of its associated television set via a control signal (44) and to return a detection signal (32) to the central device (22). The detection signal is stored in a control device (36) provided in the central device (22), indicated and used for calculating the period of use of each television set (14), and the resultant fees, by means of a computer (48). <IMAGE>