As an illuminating light source, a light emitting diode (LED) is widely used. The LED has a feature that a response speed is faster than that of an incandescent electric lamp or a fluorescent lamp. By using the feature, a visible light communication technology performing communication so as to superimpose information on illuminating light emitted from the LED by causing the LED to blink at a speed which may not be recognized by human eyes is studied. The visible light communication is researched to be used for a communication purpose in a place where the use of electric waves is limited, used for information distribution limited to a range where light such as indoor light reaches, used in intelligent transport systems (ITS), or the like.
An information transmission system including light emitting means for transmitting information through lighting a predetermined region and light receiving means for decoding the information from an image obtained by imaging the predetermined region in a time-series manner is proposed. In the information transmission system, the predetermined region emits color-modulated light by converting information into at least three levels depending on the information and the light receiving means decodes the information based on the converted color-modulated information of the predetermined region. In addition, an optical module which includes at least two primary light sources for emitting a primary color light and which incorporates data into light by modulating a color coordination of the light to be emitted from the primary light sources according to embedded data is proposed. Furthermore, there are various proposals using the features of the visible light communication.
Examples of the related art include Japanese Laid-open Patent Publication No. 3-10483, International Publication Pamphlet No. WO2009/136312, Japanese Laid-open Patent Publication No. 2011-114634, Japanese Laid-open Patent Publication No. 2010-98574, Japanese Laid-open Patent Publication No. 2011-29871, Shinichiro HARUYAMA, “Visible Light Communication”, IEICE Transactions on Information and System, Vol. J86-A, No. 12, pp. 1284 to 1291, December 2003, and Fujitsu Limited, “Development of New Communication Technique enabling Information to be acquired by simply imaging TV Video with Mobile Phone”, Jun. 4, 2012.