Patent ID: 8330380
Filing Date: 2012-12-11
Classification: H05B

Abstract:
1. A control circuit for a light emitting device, comprising: a rectifier unit for performing full wave rectification on an alternating current power source; a capacitor for smoothing a voltage having been full wave rectified in the rectifier unit; a first switching element for switching a current flowing through the light emitting device which emits light in response to the smoothed voltage; a voltage dividing circuit that includes a zener diode for interrupting the voltage dividing circuit when the smoothed voltage is decreased to a first voltage or lower, and divides the smoothed voltage to output a reference voltage when the smoothed voltage is higher than the first voltage; a comparator for comparing a comparison voltage corresponding to the current flowing through the light emitting device with the reference voltage, a control unit for controlling switching of the first switching element based on a comparison result obtained in the comparator; and a power supply circuit including a second switching element which is brought into conduction when the smoothed voltage is lower than a second voltage, and brought out of conduction when the smoothed voltage is higher than the second voltage, wherein the power supply circuit supplies the smoothed voltage via the second switching element to the control unit as a power source voltage.