Control circuit of light emitting element

摘要

A control circuit of a light-emitting element comprises a rectifying unit which full-wave rectifies an alternating current power supply, a clock generator which generates and outputs a clock signal (CLK), a first comparator which compares a comparison voltage (CS) corresponding to a current flowing to the light-emitting element and a reference voltage (REF), and a switching element which is set to an ON state in synchronization with the clock signal (CLK) and which is set to an OFF state when the comparison voltage (CS) becomes greater than the reference voltage (REF) at the first comparator, to switch the current flowing to the light-emitting element. In this structure, a period of the clock signal (CLK) generated in the clock generator is varied, to reduce or inhibit noise.

主权项

1. A method for controlling a light-emitting element comprising:
adjusting a conduction angle of an AC voltage to generate an adjusted AC voltage; rectifying the adjusted AC voltage to generate a rectified voltage; generating a current in response to the rectified voltage; adjusting the current to be intermittent using a switch so that current flow is on or off; regenerating energy stored in a choke coil in response to the current flow being off; and controlling the switch with a clock signal from a clock circuit whose period is varied, wherein the clock signal is input to a counter to generate a count signal used to vary the period of the clock signal, wherein the clock circuit includes the counter, and wherein the counter changes a counter value in response to the clock signal and a reference voltage selector unit selects one of a plurality of terminal voltages as a reference voltage based on a counter value of the counter by varying a period of the clock signal generated from the clock.