Illuminating light communication device

摘要

An illuminating light communication device comprises a constant current source, a smoothing capacitor connected to an output of the constant current source, a load circuit comprising a light emitting diode and connected to the output of the constant current source, a load change element added to the load circuit and thereby partially changing load characteristic of the load circuit, and a switch element configured to determine whether or not the load change element is added to the load circuit in accordance with a binary optical communication signal.

主权项

1. An illuminating light communication device including an illuminating light communication circuit that superimposes, on illuminating light, modulation light in accordance with a binary signal for an optical communication, and output superimposed light, the illuminating light communication circuit comprising:
a constant current source; a smoothing circuit connected across output ends of the constant current source; a load circuit comprising a light emitting diode for emitting the illumination light, one end of the load circuit being connected to one of output ends of the constant current source; an auxiliary load, one end of the auxiliary load being connected to the load circuit; and a switch; a signal generation circuit for generating the binary signal for the optical communication based on communication data and for controlling the switch by the binary signal, wherein in the illuminating light communication circuit, when the auxiliary load is added to the load circuit, a load characteristic of the load circuit changes, wherein the constant current source comprises a constant current feedback system, which comprises a converter generating a DC output, a current sensing circuit generating a voltage drop depending on a load current flowing to the load circuit, a differential amplifier, and a controller, wherein the differential amplifier amplifies a difference between the voltage drop generated in the current sensing circuit and a predetermined reference voltage, wherein the controller controls an output of the converter so that an average value of the load current becomes generally constant in accordance with an output of the differential amplifier, wherein the switch is controlled by the binary signal for the optical communication output from the signal generation circuit to add the auxiliary load to the load circuit or not in accordance with the binary signal for the optical communication, thereby superimposing the communication data to the illuminating light, and wherein the switch is controlled to be switched on/off in a high frequency domain by the binary signal for the optical communication.