| 摘要 |
A coded digital message is used for modulating a voltage supplying fluorescent tubes (5). The modulation is effected, either in frequency, or pulse duration synchronised on the network. In the first case a direct voltage is strobed and the fluorescent tubes (5) are supplied by this voltage, the strobing frequency ranging from single to double depending on the logical state of the signals constituting the message. In the second case, half-cycles on the network double frequency are applied to the fluorescent tubes (5) synchronised with the alternation of the network frequency, for a first logical state, and dephased for a second logical state. The receiver is an electronic label (7) comprising a photoelectric cell (70), a decoder, a microcontroller and a display (71). The invention is applicable particularly in the updating of electronic labels in a departmental store.
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