Illumination device and light-emitting diode circuit

Patent metadata

Field	Value
Publication number	US-9538595-B2
Application number	US-201514953410-A
Country	US
Kind code	B2
Filing date	Nov 29, 2015
Priority date	Dec 10, 2014
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

An illumination device includes a rectifier circuit, M light-emitting modules, and a control module. The rectifier circuit has a positive output terminal and a negative output terminal, and generates a driving voltage between the positive output terminal and the negative output terminal according to an input power. The M light-emitting modules are coupled between the positive output terminal and the negative output terminal. Each of the M light-emitting modules has a conduction voltage, and includes a light-emitting unit that includes at least one light-emitting diode. The control module is coupled between the rectifier circuit and the M light-emitting modules, and controls the M light-emitting modules to dynamically form S light-emitting diode strings coupled in parallel with each other. A number of the light-emitting units in each of the S light-emitting diode strings is N, in which S×N=M, where M, S, N are positive integers.

First claim

What is claimed is:

1. An illumination device, comprising:
a rectifier circuit having a positive output terminal and an negative output terminal, the rectifier circuit being configured to generate a driving voltage between the positive output terminal and the negative output terminal according to an input power;
M light-emitting modules coupled between the positive output terminal and the negative output terminal, wherein each of the M light-emitting modules has a conduction voltage, and comprises a light-emitting unit that comprises at least one light-emitting diode; and
a control module coupled between the rectifier circuit and the M light-emitting modules, and configured to control the M light-emitting modules to dynamically form a plurality of light-emitting diode strings coupled in parallel with each other,
wherein a number of the light-emitting units in each of the light-emitting diode strings is N, and a number of the light-emitting diode strings is S, and
wherein when the driving voltage is changed from one time as much as the conduction voltage to (Q+q) times as much as the conduction voltage, the N is changed from one to Q and the S is changed from M to M/Q with the change of the driving voltage, where S×N=M, and M, S, N, Q are positive integers, and 0<q<1, Q is greater than or equal to 3.

2. The illumination device of claim 1 , wherein the M light-emitting modules are coupled in series, each of the light-emitting units comprises a first terminal and a second terminal, and an n-th light-emitting module of the M light-emitting modules further comprises:
a first rectifying diode, wherein a cathode of the first rectifying diode is coupled to the first terminal of the light-emitting unit of the n-th light-emitting module;
a first switch coupled between the positive output terminal and the cathode of the first rectifying diode, and configured to be selectively turned on according to an n-th one of a plurality of first control signals; and
a second switch coupled between the negative output terminal and the second terminal of the light-emitting unit of the n-th light-emitting module, and configured to be selectively turned on according an n-th one of a plurality of second control signals,
wherein an anode of the first rectifying diode is coupled to the second terminal of the light-emitting unit of a (n−1)-th light-emitting module of the M light-emitting modules, and the control module generates the first control signals and the second control signals according to the driving voltage and the conduction voltage, wherein n is positive integer greater than 1 and smaller than M.

3. The illumination device of claim 2 , wherein a first light-emitting module of the M light-emitting modules further comprises:
a third switch coupled between the negative output terminal and the second terminal of the light-emitting unit of the first light-emitting module, and configured to be selectively turned on according to a first one of the second control signals,
wherein the first terminal of the light-emitting unit of the first light-emitting module is coupled to the positive output terminal, and the second terminal of the light-emitting unit of the first light-emitting module is coupled to the anode of the first rectifying diode of a second light-emitting module of the M light-emitting modules.

4. The illumination device of claim 3 , wherein a M-th light-emitting modules of the M light-emitting modules comprises:
a second rectifying diode, wherein a cathode of the second rectifying diode is coupled to the first terminal of the light-emitting unit of the M-th light-emitting module, and an anode of the second rectifying diode is coupled to the second terminal of the light-emitting unit of a (M−1)-th light-emitting module of the M light-emitting modules; and
a fourth switch coupled between the positive output terminal and the cathode of the second rectifying diode, and configured to be selectively turned on according to a M-th one of the first control signals,
wherein the second terminal of the light-emitting unit of the M-th light-emitting module is coupled to the negative output terminal.

5. The illumination device of claim 4 , wherein when the driving voltage is same as the conduction voltage, the third switch, and the fourth switch and the first switch and the second switch of the n-th light-emitting module are turned on, such that the light-emitting units of the M light-emitting modules are coupled in series between the positive output terminal and the negative output terminal to form M light-emitting diode strings coupled in parallel with each other, wherein the number of the light-emitting unit in the M light-emitting strings is 1, and S=M, and N=1.

6. The illumination device of claim 4 , wherein when the driving voltage is M times as much as the conduction voltage, and the third switch, the fourth switch, and the first switch and the second switch of the n-th light-emitting module are turned off, such that each the light-emitting unit of the M light-emitting modules is coupled in series between the positive output terminal and the negative output terminal to form a light-emitting diode string, wherein the number of the light-emitting unit in the light-emitting string is M, and S=1, and N=M.

7. The illumination device of claim 2 , wherein a first light-emitting module of the M light-emitting modules, a M-th light-emitting module of the M light-emitting modules, and the n-th light-emitting module have the same circuit architecture, wherein the first switch of the first light-emitting module is configured to be turned on, and the second switch of the M-th light-emitting module is configured to be turned on.

8. The illumination device of claim 7 , wherein when the driving voltage is the same as the conduction voltage, the first switch and the second switch of each of the M light-emitting modules are turned on, such that the light-emitting units of the M light-emitting modules are coupled in series between the positive output terminal and the negative output terminal to form M light-emitting diode string coupled in parallel with each other, wherein the number of the light-emitting unit in the M light-emitting strings is 1, and S=M, and N=1.

9. The illumination device of claim 7 , wherein when the driving voltage is M times as much as the conduction voltage, and the first switch and the second switch of the n-th light-emitting module, the second switch of the first light-emitting module, and the first switch of the M-th light-emitting module are turned off, such that the light-emitting units of the M light-emitting modules are coupled in series between the positive output terminal and the negative output terminal to form a light-emitting diode string, wherein the number of the light-emitting unit in the light-emitting string is M, and S=1, and N=M.

10. The illumination device of claim 2 , wherein when the driving voltage is S times as much as the conduction voltage, and the first switch of the n-th light-emitting module is turned on, and the second switch of the (n−1)-th light-emitting module is turned on, so as to form the S diode strings, wherein S is a positive integer but not equal to M.

11. The illumination device of claim 2 , wherein when the driving voltage is Z times as much as the conduction voltage, M is greater than Z and is not an integral multiple of Z, the first switch of the n-th light-emitting module is turned on, and the second switch of the (n−1)-th light-emitting module is turned on, so as to form X diode strings coupled in parallel with each other, wherein the number of the light-emitting units in each of the X diode strings is W, where X and W are positive integers, and X is not greater than Z

Assignees

• Lextar Electronics Corp

Inventors

• Chang Chun-Jong
• Huang Jhao-Cyuan
• Chen Po-Shen
• Yeh Chien-Nan

Classifications

• H05B45/44 Primary

  with an active control inside an LED matrix · CPC title

• H05B33/0824 Primary

  Electricity · mapped topic

• H05B33/0809

  Electricity · mapped topic

• H05B45/10

  Controlling the intensity of the light · CPC title