Module for controlling light emitting diode current for selective feedback, apparatus and method for driving light emitting diodes using the same

• US 8,115,413 B2
• Filed: 12/02/2009
• Issued: 02/14/2012
• Est. Priority Date: 08/31/2009
• Status: Active Grant

• Current Assignee: Skaichips Company Limited
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Kong, Seung Kon, Hwang, Bo Hyun, Kim, Jung Hyun, Kwon, Jung Sun
• Primary Examiner(s): Philogene, Haiss
• Application Number:
  US12/629,552
• Publication Number:
  US 20110050128A1
• Time in Patent Office: 804 Days
• Field of Search: 315/291, 315/294, 315/295, 315/297, 315/312, 315/318, 315/319, 315/224, 315/247, 345/82, 345/95, 345/102, 345/212, 345/204, 345/210, 345/690, 327/538
• US Class Current: 315/295
• CPC Class Codes: H05B 45/395 Linear regulators
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

The present invention provides a module for controlling an LED current for selective feedback, an apparatus and a method for driving LEDs using the same. The module for controlling the LED current, which is connected to a plurality of LED channels receiving driving powers supplied from at least one DC/DC converter and controls currents of the LED channels through a constant current, the LED current controlling module includes: an operation mode selector for selecting an operation mode according to an inputted enable signal level; a channel divider for dividing a plurality of LED channels into at least one group according to the selected operation mode; and a minimum voltage selector for selecting an LED channel with a minimum voltage, obtained by comparing voltages detected from each of lower ends of the LED channels included in each of one or more divided groups.

Claims

1. An LED current controlling module which is connected to a plurality of LED channels receiving driving powers supplied from at least one DC/DC converter and controls currents of the LED channels through a constant current, the LED current controlling module comprising:

an operation mode selector for selecting an operation mode according to an inputted enable signal level;

a channel divider for dividing a plurality of LED channels into at least one group according to the selected operation mode; and

a minimum voltage selector for selecting an LED channel with a minimum voltage, obtained by comparing voltages detected from each of lower ends of the LED channels included in each of one or more divided groups.

2. The LED current controlling module of claim 1, further comprising a feedback controller for transferring a minimum lower end voltage of the selected LED channel to a DC/DC converter supplying a driving power to the LED channel.

3. The LED current controlling module of claim 1, wherein the enable signal level of the operation mode selector has three signal levels.

4. The LED current controlling module of claim 1, wherein the operation mode includes a first operation mode based on the fact that the plurality of LED channels receive a driving power supplied from an identical DC/DC converter, and a second operation mode based on the fact that the plurality of LED channels receive a driving power supplied from at least two DC/DC converters, and the operation mode selector selects one of the first and second operation modes according to the inputted enable signal.

5. The LED current controlling module of claim 4, wherein the channel divider divides a plurality of LED channels into one group when the operation mode selector selects the first operation mode, and the channel divider divides a plurality of LED channels into an LED channel group which receives a driving power supplied from the identical DC/DC converter when the operation mode selector selects the second operation mode.

6. An apparatus for driving LEDs comprising:

light source units including a plurality of LED channels connected to be parallel to one another;

at least one DC/DC converter for supplying a driving power to the light source units;

at least one LED current controlling module connected to LEDs, selected from among a plurality of LED channels included in the light source units to have the same number as a preset number, said at least one LED current controlling module which determines an operation mode of the plurality of the connected LED channels according to an enable signal, divides the connected LED channels into at least one group, selects a minimum voltage of voltages for LED channels included in each group, and feedback-receives the selected voltage to the DC/DC converter; and

an enable signal distributor for distributing an enable signal corresponding to a preset operation mode of said at least one LED current controlling module into each of the LED current controlling modules.

7. The apparatus of claim 6, wherein the enable signal distributor distributes an enable signal according to whether a plurality of LED channels connected to the LED current controlling modules receive a driving power supplied from either an identical DC/DC converter or at least two DC/DC converters.

8. The apparatus of claim 6, wherein the LED current controlling module comprises:

an operation mode selector for selecting an operation mode according to an inputted enable signal level;

a channel divider for dividing a plurality of the connected LED channels into at least one group, according to the selected operation mode;

a minimum voltage selector for selecting an LED channel with a minimum voltage obtained by comparing voltages of each of lower ends of the LED channels included in each of one or more divided groups; and

a feedback controller for transferring a minimum lower end voltage of the selected LED channel to the DC/DC converter that supplies a driving power to the LED channel.

9. The apparatus of claim 8, wherein the enable signal level of the operation mode selector has three signal levels.

10. The apparatus of claim 8, wherein the operation mode includes a first operation mode based on the fact that the plurality of LED channels receive a driving power supplied from the identical DC/DC converter, and a second operation mode based on the fact that the plurality of LED channels receive a driving power supplied from at least two DC/DC converters, and the operation mode selector selects one of the first and second operation modes according to an inputted enable signal.

11. The apparatus of claim 8, wherein the channel divider divides the plurality of LED channels into one group when the operation mode selector selects the first operation mode, and the channel divider divides the plurality of LED channels into an LED group that receives a driving power supplied from the identical DC/DC converter.

12. A method for driving LEDs in an LED current controlling module which is connected to a plurality of LED channels and controls currents of the LED channels through a constant current, the method comprising the steps of:

selecting an operation mode according to an inputted enable signal level;

dividing the plurality of LED channels into at least one group according to the selected operation mode;

selecting an LED channel with a minimum voltage, obtained by comparing voltages of lower ends of LED channels included in each of one or more divided groups; and

feedback-receiving a voltage of the selected LED to a DC/DC converter that supplies a driving power to an LED channel of each group.

13. The method of claim 12, wherein, in the step of selecting the operation mode according to the inputted enable signal level, one of a first operation mode and a second operation mode is selected, wherein the first operation mode being based on the fact that the plurality of LED channels receive a driving power supplied from an identical DC/DC converter, and the second operation mode being based on the fact that the plurality of LED channels receive a driving power supplied from at least two DC/DC converters.

14. The method of claim 13, wherein, in the step of dividing the plurality of LED channels into said at least one group according to the selected operation mode, the plurality of LED channels are divided into one group when the first operation mode is selected, and the plurality of LED channels are divided into an LED channel group which receives a driving power supplied from the identical DC/DC converter when the second operation mode is selected.