LED lighting apparatus having improved flicker performance

Abstract

Provided is a lighting apparatus using LEDs (light-emitting diodes having improved flicker performance. In general, in a direct-drive LED lighting apparatuses of the related art which use no switching-mode power supply (SMPS), percent flicker (hereinafter referred to as “% F”) is 100%. In contrast, the % F of the LED lighting apparatus having improved flicker performance according to the present invention is 40% or less that is equivalent to the % F of fluorescent lamps using a magnetic ballast.

The invention claimed is: 
     
       1. An LED lighting apparatus having improved flicker, comprising:
 an AC power supply which supplies a first-phase AC voltage and a second-phase AC voltage; 
 first and second rectifier circuits which convert the AC voltages into DC rectified voltages; 
 first and second LED blocks each including one or more LEDs as a load; 
 first and second current limiting devices each of which limits an amount of current; 
 a first LED lighting block comprising the first rectifier circuit which rectifies the first-phase AC voltage, a first LED block which is driven by an output from the first rectifier circuit, and the first current limiting device which limits the amount of current of the first LED block; and 
 a second LED lighting block comprising the second rectifier circuit which rectifies the second-phase AC voltage, a second LED block which is driven by an output from the second rectifier circuit, and the second current limiting device which limits the amount of current of the second LED block, 
 wherein, when a point of time where each of the AC voltages supplied to a corresponding LED lighting block of the LED lighting blocks passes through a zero voltage and starts to increase is set to a voltage phase 0°, a current starts to be supplied to each of the LED lighting blocks and light emission starts before a voltage phage 10°, and a percent flicker of each of the LED lighting blocks is 100%. 
 
     
     
       2. The LED lighting apparatus according to  claim 1 , further comprising:
 a third LED lighting block comprising an AC power supply which supplies a third-phase AC voltage; 
 a third rectifier circuit which rectifies the third-phase AC voltage; 
 a third LED block which is driven by an output from the third rectifier circuit; and a third current limiting device which limits an amount of current of the third LED block, 
 wherein, when a point of time where each of the AC voltages supplied to a corresponding LED lighting block of the LED lighting blocks passes through a zero voltage and starts to increase is set to a voltage phase 0°, a current starts to be supplied to each of the LED lighting blocks and light emission starts before a voltage phage 40°, and a percent flicker of each of the LED lighting blocks is 100%. 
 
     
     
       3. The LED lighting apparatus according to  claim 2 ,
 wherein the first LED block comprises a light emitting block in which two or more sub-LED blocks are connected in series, and the first LED lighting block further includes a first switch block (composed of one or more switches) which adjusts a number of the sub-LED blocks that are lighted by changing a current flow and a first controller (which controls the first current limiting device and the first switch block), 
 wherein the second LED block comprises a light emitting block in which two or more sub-LED blocks are connected in series, and the second LED lighting block further includes a second switch block (composed of one or more switches) which adjusts a number of the sub-LED blocks that are lighted by changing a current flow and a second controller (which controls the second current limiting device and the second switch block), 
 wherein the third LED block comprises a light emitting block in which two or more sub-LED blocks are connected in series, and the third LED lighting block further includes a third switch block (composed of one or more switches) which adjusts a number of the sub-LED blocks that are lighted by changing a current flow and a third controller (which controls the third current limiting device and the third switch block), 
 wherein, when a point of time where each of the AC voltages supplied to a corresponding LED lighting block of the LED lighting blocks passes through a zero voltage and starts to increase is set to a voltage phase 0°, a current starts to be supplied to each of the LED lighting blocks and light emission starts before a voltage phage 30°, and 
 wherein the first to third controllers respectively control the first to third current limiting devices with a sine wave signal (hereinafter referred to as a “sine wave one signal”) having a same phase as the rectified voltages. 
 
     
     
       4. The LED lighting apparatus according to  claim 3 , wherein the first to third controllers respectively control the first to third current limiting devices in a form of a staircase wave based on one of an instantaneous rectified voltage or a rectified voltage phase. 
     
     
       5. The LED lighting apparatus according to  claim 3 , wherein the first to third controllers generate a sine wave signal (hereinafter referred to as a “sine wave two signal”) that has a lower frequency than a rectified frequency, and respectively control the first to third current limiting devices such that a current corresponding to the sine wave two signal is supplied to the load. 
     
     
       6. The LED lighting apparatus according to  claim 1 , wherein the first LED block comprises a light emitting block in which two or more sub-LED blocks are connected in series, and the first LED lighting block further includes a first switch block (composed of one or more switches) which adjusts a number of the sub-LED blocks that are lighted by changing a current flow and a first controller (which controls the first current limiting device and the first switch block), wherein the second LED block comprises a light emitting block in which two or more sub-LED blocks are connected in series, and the second LED lighting block further includes a second switch block (composed of one or more switches) which adjusts a number of the sub-LED blocks that are lighted by changing a current flow and a second controller (which controls the second current limiting device and the second switch block), and wherein the first and second controllers respectively control the first and second current limiting devices with a sine wave signal (hereinafter referred to as a “sine wave one signal”) having a same phase as the rectified voltages. 
     
     
       7. The LED lighting apparatus according to  claim 6 , wherein the first and second controllers respectively control the first and second current limiting devices in a form of a staircase wave based on one of an instantaneous rectified voltage or a rectified voltage phase. 
     
     
       8. The LED lighting apparatus according to  claim 6 , wherein the first and second controllers generate a sine wave signal (hereinafter referred to as a “sine wave two signal”) that has a lower frequency than a rectified frequency, and respectively control the first and second current limiting devices such that a current corresponding to the sine wave two signal is supplied to the load.