Patent ID: 8810155
Filing Date: 2014-08-19
Classification: H04B,H05B

Abstract:
1. An illumination light communication device comprising: a light source unit including light emitting elements; a power supply unit which controls a load current flowing through the light source unit to be maintained at a constant value based on a dimming signal; an impedance unit connected in series to the light source unit to vary an impedance; a switch element connected in parallel to the impedance unit to connect or disconnect the impedance unit with the light source unit; and a control unit configured to control on/off of the switch element to modulate a light intensity of illumination light outputted from the light source unit such that a binary communication signal is superimposed on the illumination light, wherein the control unit controls the impedance of the impedance unit such that a difference between a magnitude of the load current when a pulse of the communication signal is superimposed and a magnitude of the load current when a pulse of the communication signal is not superimposed is maintained constant regardless of a dimming rate of the dimming signal in a range of the dimming rate being equal or greater than a predetermined dimming rate.