Patent ID: 8734513

Claim:
An artificial retinal system comprising: an external optical device including: an image generator for receiving an external image, and operable to provide a target image associated with the external image and to output the target image by optical projection; and a background light generator for providing a background light; and a retinal implant chip including: a solar cell to be disposed within an illumination range of the background light for receiving the background light and operable to convert the background light into electrical power; and a stimulus generator to be disposed to receive the target image projected by said image generator and the background light provided by said background light generator, said stimulus generator being coupled to said solar cell for receiving the electrical power therefrom and including an image sensing stimulator that is operable to convert the target image into electrical stimuli, said stimulus generator further including a contrast enhancer for reducing effect of the background light received by said stimulus generator on the electrical stimuli generated by said image sensing stimulator; wherein said contrast enhancer is to be disposed within the illumination range of the background light for receiving the background light and is operable to convert the background light into correction current; wherein said image sensing stimulator is configured to receive and convert the target image and the background light into an initial electrical output, is coupled to said contrast enhancer for receiving the correction current therefrom, and is operable to correct the initial electrical output using the correction current so as to generate the electrical stimuli; and wherein said contrast enhancer includes: a background light sensor operable to sense and convert the background light into background photocurrent; and a current mirror having an input end coupled to said background light sensor for receiving the background photocurrent, and at least one output end for outputting the correction current, the correction current having an amplitude corresponding to that of the background photocurrent; and wherein said image sensing stimulator being coupled to said output end of said current mirror for receiving the correction current therefrom.