this is SUMMARY about 专利US8659238.good for the eye ?

SUMMARY

In general, in one aspect, this specification describes a switching power supply with power feedback that keeps lamp's brightness constant. There are two feedback loops: one is voltage feedback loop that is an electrical circuit sampling output voltage across lamp and sends signal proportional to output voltage to controller; the other is current feedback loop that is an electrical circuit sampling output current through lamp and sends signal proportional to output current to controller. In the controller, voltage feedback signal and current feedback signal are sent to signal processing circuit. The signal processing circuit derives a power feedback signal that is multiplication product of voltage feedback signal and current feedback signal. The power feedback signal is proportional to output power and then is compared to reference circuit that predetermines output power value. Then the error signal between output power feedback signal and reference is used to create a pulse. And the pulse is sent to driver to change on time of main switch to keep output power constant at predetermined value. The output power of lamp is constant and so the lamp has constant brightness without flickering.

Particular implementations can include one or more of the following features. The power supply can include a filter to prevent high frequency current from entering input voltage. The power supply can include a protection that cut off connection between input voltage and the power supply in case short circuit or over current happens. The power supply can further include a bridge rectifier operable to rectify an alternating current (AC) voltage and produce DC input voltage The bridge rectifier can include four diodes connected in a bridge configuration. The converter can be a flyback converter that converts input voltage to a DC voltage output for output device with predetermined output power. The controller can adjust the on time of main switch in the converter. The voltage feedback circuit can send feedback signal from secondary to primary by auxiliary transformer winding or opto-coupler. The current feedback circuit can use current sense resistor or signal transformer to sample current feedback signal.

In general, in another aspect, the specification describes a method that includes: sampling both current and voltage and feeding back both signals to controller; generating a power feedback signal by multiplying current feedback signal and voltage feedback signal; comparing feedback signal to reference with Opamp and sending error signal to comparator; comparing error signal with sawtooth generator and generating a signal pulse to driver; sending a power pulse to main switch of converter to control on time by driver; and controlling on time of main switch to output constant power to output device.