| 主权项 |
1. A light emitting system comprising:
a light emitting device that has a forward voltage with a magnitude dependent on an ambient parameter when driven with current; and
an optical power control device including:a control signal module including:
a reference voltage unit coupled to said light emitting device for detecting the forward voltage thereof, and outputting a reference voltage according to the forward voltage of said light emitting device; anda control signal generator coupled to said reference voltage unit for receiving the reference voltage, and operable to generate, according to the reference voltage, a control signal having a parameter associated with the reference voltage; and a current controller coupled to said light emitting device, and coupled to said control signal generator for receiving the control signal, said current controller being operable to permit flow of a driving current through said light emitting device, the driving current being associated with the parameter of the control signal,
wherein:said current controller is configured such that the driving current has an average magnitude proportional to the parameter of the control signal;said reference voltage unit is configured such that the reference voltage has a magnitude associated with an average magnitude of the forward voltage;said control signal generator is configured such that the parameter of the control signal is associated with the magnitude of the reference voltage;the control signal is a pulse signal, and the parameter of the control signal is a duty cycle of the pulse signal, the driving current being a pulse current, the reference voltage being a direct-current (DC) voltage; and said reference voltage unit includes:
a forward voltage detector coupled to said light emitting device for detecting the forward voltage thereof, and operable to output a detection signal that is a pulse voltage, and that has a magnitude varying with the magnitude of the forward voltage of said light emitting device;a voltage integrator coupled to said forward voltage detector for receiving the detection signal, and operable to integrate the detection signal for generating an integration signal that is a DC voltage signal;a power amplifier coupled to said voltage integrator for receiving the integration signal, and operable to amplify the integration signal for generating an amplified integration signal; anda level shifter coupled to said power amplifier for receiving the amplified integration signal, and operable to shift a voltage level of the amplified integration signal according to a predetermined DC voltage, so as to generate the reference voltage. |
