LED LIGHTING MODULE HAVING TUNABLE CORRELATED COLOR TEMPERATURE AND CONTROL METHOD THEREOF

• US 20170006684A1
• Filed: 06/21/2016
• Published: 01/05/2017
• Est. Priority Date: 07/02/2015
• Status: Abandoned Application

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Tu, Kuan-Hsien, Huang, Ying-Hao
• Application Number:
  US15/188,400
• Publication Number:
  US 20170006684A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

A LED lighting module having tunable correlated color temperature and control method thereof is disclosed. The control method comprises steps of: (a) receiving an AC voltage signal and converting the AC input signal into a first AC signal; (b) receiving the first AC signal and converting the first AC signal into a first DC signal; (c) comparing the first DC signal with a plurality of reference voltages by the control unit, wherein the reference voltages comprise driven voltages of one of the LED strings or driven voltages of serially-connected LED strings; and (d) if the first DC signal exceeds the reference voltage of the corresponding LED string or the corresponding serially-connected LED strings, the corresponding LED string or the corresponding serially-connected LED strings is driven so as to adjust the correlated color temperature of the light emitted by the LED lighting module.

Claims

1. A LED lighting module having tunable correlated color temperature, comprising:

a dimmer unit configured to receive an AC input signal and convert the AC input signal into a first AC signal;

a rectifier unit electrically connected with an output of the dimmer unit and configured to receive the first AC signal and convert the first AC signal into a first DC signal;

a LED lighting unit electrically connected with the rectifier unit and configured to receive the first DC signal, wherein the LED lighting unit comprises a plurality of LED strings, each of the LED strings has a predetermined correlated color temperature, and the LED strings have at least two different correlated color temperatures; and

a control unit electrically connected with the rectifier unit, the LED lighting unit and a ground point, and configured to receive the first DC signal and control the current to flow through the LED strings according to the comparing results between the first DC signal and a plurality of reference voltages, wherein the reference voltages comprise driven voltages of one of the LED strings or driven voltages of serially-connected LED strings,

wherein if the first DC signal exceeds the reference voltage of the corresponding LED string or the corresponding serially-connected LED strings, the corresponding LED string or the corresponding serially-connected LED strings is driven so as to adjust the correlated color temperature of the light emitted by the LED lighting module.

2. The LED lighting module according to claim 1, wherein the dimmer unit includes a TRIAC circuit.

3. The LED lighting module according to claim 1, wherein the rectifier unit includes a full-bridge circuit.

4. The LED lighting module according to claim 1, wherein the control unit comprises a control circuit, and the control circuit comprises an output channel electrically connected to the rectifier unit for outputting the first DC signal.

5. The LED lighting module according to claim 4, wherein the LED lighting unit comprises N LED strings including a first LED string to a Nth LED string connected in series, and the control circuit includes N driving channel including a first driving channel to a Nth driving channel, wherein the first driving channel is electrically connected to a node between the first LED string and the second LED string, the (N-1)th driving channel is electrically connected to a node between the (N-1)th LED string and the Nth LED string, and the Nth driving channel is electrically connected to one terminal of the Nth driving channel, wherein the Nth driving channel is configured to drive the corresponding serially-connected LED strings from the first LED string to the Nth LED strings.

6. The LED lighting module according to claim 5, wherein each of the LED strings has a specific driven voltage, and the reference voltages comprise N reference voltages from a first reference voltage to a Nth reference voltage, wherein the first reference voltage is the driven voltage of the first LED string, and the Nth reference voltage is a sum of the driven voltages from the first LED string to the Nth LED string.

7. The LED lighting module according to claim 6, wherein if the first DC signal exceeds to the first reference voltage, the first driving channel is enabled to drive the first LED string, wherein if the first DC signal exceeds the Nth reference voltage, the Nth driving channel is enabled to drive the corresponding serially-connected LED strings from the first LED string to the Nth LED string.

8. The LED lighting module according to claim 1, wherein the control unit comprises a plurality of control circuits and a switch circuit, wherein the control circuits comprises N control circuits including a first control circuit to a Nth control circuit, the switch circuit is configured to receive the first DC signal to drive the control circuits.

9. The LED lighting module according to claim 8, wherein the LED lighting unit comprises N LED strings including a first LED string to a Nth LED string, and the control unit comprises N control circuits including a first control circuit to Nth control circuit, wherein each of the control circuits includes a first driving channel, a second driving channel and an output channel, wherein the first driving channel of the first control circuit is electrically connected to a node between the first LED string and the second LED string, the second driving channel of the first control circuit is electrically connected to one terminal of the second LED string, wherein the first driving channel of the (N-1)th control circuit is electrically connected to the output channel of the (N-2)th control circuit and one terminal of the Nth LED string, and the second driving channel of the (N-1)th control circuit is electrically connected to the other terminal of the Nth LED string, wherein the first driving channel of the Nth control circuit is electrically connected to the output channel of the (N-1)th control circuit through the switch circuit.

10. The LED lighting module according to claim 9, wherein each of the LED strings has a specific driven voltage, and the reference voltages comprise N reference voltages including a first reference voltage to a Nth reference voltage, wherein the first reference voltage is the driven voltage of the first LED string, and the Nth reference voltage is a sum of the driven voltages from the first LED string to the Nth LED string.

11. The LED lighting module according to claim 10, wherein if the first DC signal exceeds to the first reference voltage, the first driving channel of the first control circuit is enabled to drive the first LED string, wherein if the first DC signal exceeds to the second reference voltage, the first driving channel of the second control circuit is enabled to drive the first LED string and the second LED string through the second driving channel of the first control circuit, and wherein if the first DC signal exceeds the Nth reference voltage, the first driving channel of the Nth control circuit is enabled to drive the LED strings from the first LED string to Nth LED string through the second driving channel of the (N-1)th control circuit.

12. The LED lighting module according to claim 1, further comprising a circuit board, wherein the rectifier unit, the LED lighting unit and the control unit are disposed on a surface of the circuit board.

13. The LED lighting module according to claim 12, wherein all of the LED strings are disposed on the same surface of the circuit board, wherein the circuit board are divided into a first ring area, a second ring area and a third ring area, wherein the rectifier unit and the control unit are disposed on the first ring area, at least one LED string of the LED strings is disposed on the third ring area, and the other LED strings are disposed on the second ring area.

14. The LED lighting module according to claim 12, wherein all of the LED strings are disposed on the same surface of the circuit board, and the circuit board are divided into a first ring area and a second ring area, wherein the rectifier unit and the control unit are disposed on the second ring area, and the LED strings are disposed on the first ring area.

15. The LED lighting module according to claim 12, wherein the LED strings having at least two different predetermined correlated color temperatures are disposed on the surface of the circuit board with symmetrical and interspersed arrangement.

16. The LED lighting module according to claim 1, wherein the LED strings comprises a first LED string, a second LED string and a third LED string, wherein the predetermined correlated color temperature value of the first LED string is 1900K, the predetermined correlated color temperature value of the second LED string is 3000K, the predetermined correlated color temperature value of the third LED string is 4000K, and the correlated color temperature of the LED lighting module is ranged from 1900K to 2700K.

17. The LED lighting module according to claim 1, wherein the LED strings comprises a first LED string, a second LED string and a third LED string, wherein the predetermined correlated color temperature value of the first LED string is 1900K, the predetermined correlated color temperature value of the second LED string is 4000K, the predetermined correlated color temperature value of the third LED string is 5000K, and the correlated color temperature of the LED lighting module is ranged from 1900K to 3000K.

18. The LED lighting module according to claim 1, wherein the correlated color temperature of the light emitted by the LED lighting module is located between a largest predetermined correlated color temperature value and a smallest predetermined correlated color temperature value of the driven LED strings.

19. A control method for performing a correlated color temperature adjustment of a LED lighting module, wherein the LED lighting module comprises a dimmer unit, a rectifier unit, a control unit and a LED lighting unit, the LED lighting unit includes a plurality of LED strings, each of the LED strings has a predetermined correlated color temperature, and the LED strings have at least two different correlated color temperatures, the control method comprising steps of:

(a) receiving an AC voltage signal and converting the AC input signal into a first AC signal by the dimmer unit;

(b) receiving the first AC signal and converting the first AC signal into a first DC signal by the rectifier unit;

(c) comparing the first DC signal with a plurality of reference voltages by the control unit, wherein the reference voltages comprise driven voltages of one of the LED strings or driven voltages of serially-connected LED strings; and

(d) if the first DC signal exceeds the reference voltage of the corresponding LED string or the corresponding serially-connected LED strings, the corresponding LED string or the corresponding serially-connected LED strings is driven so as to adjust the correlated color temperature of the light emitted by the LED lighting module.