US Patent 7294978 Efficient lighting

A method for efficient lighting includes supplying power to a light source to control the intensity of light emitted from the light source according to an intensity waveform. The amplitude of the waveform over one period is at a high level for a first time interval and at or below a low level for a second time interval. The method includes selecting durations of the first time interval according to a first characteristic of human visual perception and selecting the second time interval according to a second characteristic of human visual perception.