Patent ID: 8253353

Claim:
Method for driving a light source, wherein the light source is alternately switched ON and OFF in an ON/OFF pattern, wherein the duty cycle of the ON/OFF pattern is varied to vary the average light intensity of the light source, and wherein the shape of the ON/OFF pattern is varied to transmit data, comprising the steps of: defining a duty cycle ratio Δ in the range from 0 to 1, Δ being unequal to 0.5; defining a time base divided into time cells having a duration Tc; wherein each time cell is subdivided into two cell segments; wherein, in at least one time cell, the first cell segment has a duration Δ·Tc, the second cell segment has a duration (1−Δ)·Tc, and the light source is switched ON in the first cell segment and switched OFF in the second cell segment for coding a bit having a first value; and wherein, in at least one other time cell, the first cell segment has a duration (1−Δ)·Tc, the second cell segment has a duration Δ·Tc, and the light source is switched OFF in the first cell segment and switched ON in the second cell segment for coding a bit having a second value different from the first value.