Patent ID: 8805202

Claim:
An apparatus for visible light communication, comprising: a light transmitting unit configured to transmit a visible light beam of a first color, which has been modulated with first transmission data, and a visible light beam of a second color different from the first color and not modulated with data, wherein the light transmitting unit includes a first light emitting diode emitting the first color and a second light emitting diode emitting the second color; a light reception unit configured to receive the visible light beam of the first color, which has been modulated with the first transmission data, and the visible light beam of the second color different from the first color and not modulated with data; wherein the light reception unit includes: a first optical filter configured to extract the visible light beam of the first color; a second optical filter configured to extract the visible light beam of the second color; a demodulation unit configured to demodulate the first transmission data from the visible light beam of the first color extracted by the first optical filter; a retroflection unit configured to generate a reflected light beam from the visible light beam of the second color extracted by the second optical filter, wherein the retroreflection unit is a corner cube reflector in the from of a prism, the reflected light beam is reflected on first and second internal surfaces of the prism, one of the first and second internal surfaces of the prism is a shutter that changes the reflectivity of the one surface, and the shutter is a liquid crystal shutter; and a transmission unit configured to modulate the reflected light beam with second transmission data, and to transmit the modulated reflected light beam to another apparatus, wherein the transmission unit includes a modulation unit configured to change retroreflection reflectance of the retroreflection unit in accordance with the second transmission data by controlling the shutter, and the modulation unit modulates the reflected light with the second transmission data.