Patent attributes
A circuit includes a power supply circuit and a ripple reduction circuit. The power supply circuit supplies a Direct Current (DC) lighting current to a light emitting circuit. The lighting current has a ripple current at a ripple frequency. The ripple reduction circuit receives the lighting current, and performs, based on the received lighting current, Pulse Width Modulation (PWM) of the lighting current at a PWM frequency. The PWM frequency is higher than the ripple frequency. By performing the PWM, the ripple reduction current reduces variations in a magnitude of the lighting current at the ripple frequency. The PWM frequency may be higher than a frequency at which variations in the magnitude of the light produced by the lighting circuit have a harmful effect on the human eye.
