Patent ID: 8000652

Claim:
In a sending device, a method of sending information to a receiving device, wherein the sending device comprises a display unit and a hot spot of the display unit, which hot spot is configured to emit visible light of various wavelengths (λ, λ+Δλ), the method comprising: converting the information to be sent, into a sequence of differences per time unit (Δλ/t) between a norm wavelength (λ) and a second wavelength (λ+Δλ), sending a marker comprising light with a certain color, which is emitted for a certain time period to the receiving device, sending visible light of the norm wavelength (λ) to the receiving device; and sending visible light of the second wavelength (λ+Δλ) to the receiving device, wherein the per time unit (Δλ/t) between the norm wavelength (λ) and the second wavelength (λ+Δλ) corresponds to the information to be sent to the receiving device, while the firstly sent norm wavelength (λ) of the visible light is arbitrary.