APPARATUS AND METHODOLOGY FOR ENHANCING EFFICIENCY OF A POWER DISTRIBUTION SYSTEM HAVING POWER FACTOR CORRECTION CAPABILITY BY USING A SELF-CALIBRATING CONTROLLER

• US 20090315467A1
• Filed: 03/23/2009
• Published: 12/24/2009
• Est. Priority Date: 06/24/2008
• Status: Active Grant

• Current Assignee: Polaris PowerLED Technologies, LLC (Microchip Technology Incorporated)
• Original Assignee: mSilica, Inc. (Microchip Technology Incorporated)
• Inventors: Schindler, Matthew, Santo, Hendrik, S, Dilip, Dhayagude, Tushar
• Granted Patent: US 8,314,572 B2
• Time in Patent Office: Days
• US Class Current: 315/185.R
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

The present invention relates to circuits and methods for controlling one or more LED strings. The circuit comprises a programmable controller coupled to one or more detectors, wherein the one or more detectors are configured to detect one or more measurable parameters of one or more LEDs or LED drivers. The controller is configured to receive information from the one or more detectors related to the one or more measurable parameters and use that information to determine the desired drive voltage for the LED strings. The controller is associated with a power supply having power factor correction (PFC) capability. The controller provides the power supply with a control signal indicative of the desired drive voltage for one or more LED strings. The power supply also receives ac voltage and current waveforms as inputs and performs power factor correction and rectified waveforms related to the ac waveforms. The power supply generates the desired drive voltage based on the control signal.

Claims

1. A circuit for controlling one or more LED strings comprising:

a programmable controller;

a detector associated with the programmable controller;

a power supply having a power factor correction capability;

the detector for detecting a first measurable parameter of the one or more LED strings;

the programmable controller configured to receive information from the detector related to the measurable parameter;

the programmable controller for using the information to determine a desired drive voltage level value;

the programmable controller for generating a control signal indicative of the desired drive voltage value;

the power supply for receiving the control signal as a first input;

the power supply for receiving an ac voltage waveform as a second input;

the power supply for generating a drive voltage based on the control signal.

2. The circuit of claim 1, wherein the detector includes a detector for detecting an upper limit of a triode region voltage range.

3. The circuit of claim 1, wherein the detector includes a detector for detecting an ambient temperature of a LED string.

4. The circuit of claim 1, wherein the detector includes a detector for detecting a luminous intensity of a LED.

5. The circuit of claim 1, wherein the detector includes a detector for detecting a wavelength of the light emitted by at least one of the LEDs.

6. The circuit of claim 1, wherein the programmable controller generates the control signal relative to the start up of at least one of the one or more LED strings.

7. The circuit of claim 1, wherein the programmable controller generates the control signal relative to a change in a second measurable parameter in at least one of the one or more LED strings.

8. The circuit of claim 1, wherein the programmable controller generates the control signal at a fixed or variable time interval.

9. The circuit of claim 1, wherein the programmable controller comprises a DAC and a state machine.

10. The circuit of claim 1, further comprising:

the circuit is implemented in a liquid crystal display.

11. A method for controlling one or more LED strings comprising:

detecting a measurable parameter of the one or more LED strings;

receiving information from the detector related to the measurable parameter;

generating a control signal indicative of a desired drive voltage for the one or more LED strings based on the information;

performing a power factor correction related to ac current and ac voltage waveforms inputs for a power supply; and

causing the power supply to generate a desired drive voltage based on the control signal.

12. The circuit of claim 11, wherein the control signal can include a current signal.

13. The circuit of claim 11, wherein the power factor correction includes causing the current waveform to be in phase with the voltage waveform.

14. The method of claim 11, wherein the measurable parameters can be selected from the group consisting of the ambient temperature of a LED, the current flowing through a LED, the voltage across a LED, the luminous intensity of a LED, and a wavelength of the light emitted by a LED.

15. The method of claim 11, wherein the generating of the control signal is initiated relative to the start up of at least one of the LED strings.

16. The method of claim 11, wherein the generating of the control signal is initiated relative to a change in a measurable parameter.

17. A liquid crystal display including a system for controlling one or more LED strings for backlighting comprising:

a programmable decentralized controller;

a detector associated with the controller;

a power supply having power factor correction capability associated with the controller;

the detector configured to detect an upper limit level for a triode region voltage range for a LED string;

the controller configured to receive information from the detector and generate a control signal indicative of a desired drive voltage level;

the power supply for receiving the control signal as a first input and an ac voltage waveform as a second input;

the power supply configured to generate a drive voltage waveform having the desired drive voltage level.

18. The circuit of claim 17, wherein the detector includes a detector for detecting an ambient temperature of a LED string.

19. The circuit of claim 17, wherein the control signal includes a current signal.

20. The circuit of claim 17, wherein the control signal includes a voltage signal.