load current is lower than the rated current value meaning the input voltage currently generated by the power source 21 is not high enough to drive the led 27 to emit light the controller 23 generates the second control signal instead continued from the above the transistor switch 24 cuts off the current between its input end and output end upon receiving the first control signal and allows passage of current between its input end and output end upon receiving the second control signal thus by means of switch control the led 27 can be driven to emit light continuously as in the previous embodiment fig6 is a schematic circuit diagram of the led driver circuit according to the third preferred embodiment of the present invention as shown in the drawing the led driver circuit 202 in this embodiment includes a power source 21 a controller 23 a first switch device 31 a second switch device 32 at least one led 27 and a capacitor 29 the positive electrode of the capacitor 29 and the positive electrode of the led 27 are respectively connected to the positive electrode of the power source 21 via the first switch device 31 the first switch device 31 is configured to prevent the discharge current.