Method and apparatus for controlling driving current of illumination source in a display system

• US 7,057,359 B2
• Filed: 10/28/2003
• Issued: 06/06/2006
• Est. Priority Date: 10/28/2003
• Status: Expired due to Term

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Lo, I-Hsin, Hung, Ghi-Mao
• Primary Examiner(s): Lee, Wilson
• Application Number:
  US10/695,592
• Publication Number:
  US 20050093488A1
• Time in Patent Office: 952 Days
• Field of Search: 315149-159, 315/291, 315/307, 315/308, 315/169.3, 315/247, 315/312, 315/314, 315/316, 315/318, 315/224, 345/611, 345/39, 345/63, 345 48- 50, 345 87- 89, 345/104
• US Class Current: 315/291
• CPC Class Codes: H05B 31/50 specially adapted for ac
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/345 Current stabilisation; Maintaining constant current
• CPC Class Codes: H05B 47/18 via data-bus transmission

Abstract

The present application describes a programmable current controller for regulating an operating driving current flowing through an illumination source. The driving current is regulated according to a digital reference corresponding to a predetermined operating current for the illumination source. The digital reference can be converted into a reference electrical parameter (current or voltage). The reference electrical parameter is compared with an operating electrical parameter (current or voltage) corresponding to the operating driving current of the illumination source. Based on the comparison, a driving bias current is generated, which is used to regulate the operating driving current of the illumination source.

Claims

1. A display system comprising:

a display panel having at least one illumination source; and

a programmable current controller coupled to the at least one illumination source, wherein the programmable current controller is configured to regulate an operating driving current of the at least one illumination source according to a digital reference programmable by a user and corresponding to a predetermined reference driving current,

the programmable current controller comprising;

a programmable interface configured to program the digital reference in a memory;

a digital-to-analog converter coupled to the programmable interface and configured to convert the digital reference into a first electrical parameter;

a comparator coupled to the programmable interface and configured to compare the first electrical parameter with a second electrical parameter corresponding to the operating driving current of the at least one illumination source, and generate a driving bias current; and

a current regulator coupled to the comparator and configured to regulate the operating driving current of the at least one illumination source according to the driving bias current, wherein the driving bias current corresponds to a difference between the first and second electrical parameters.

2. A display system according to claim 1, wherein the programmable current controller further comprising:

a sensor coupled to the at least one illumination source and configured to measure the second electrical parameter.

3. A display system according to claim 1, wherein the sensor is a resistor.

11. A display system according to claim 1, wherein the programmable interface is an inter-integrated circuit serial interface.

12. A display system according to claim 1, wherein the programmable interface is three-wire serial interface.

4. A method of regulating an operating driving current for at least one illumination source of a display system comprising:

measuring a first electrical parameter corresponding to the operating driving current of the at least one illumination source;

converting a digital reference into a second electrical parameter, wherein the digital reference is programmable by a user and corresponds to a predetermined driving current for the at least one illumination source;

comparing the first electrical parameter with the second electrical parameter;

based on the comparison, generating a driving bias current; and

regulating the operating driving current of the at least one illumination source according to the driving bias current.

5. A method according to claim 4, wherein the first electrical parameter is a feedback voltage corresponding to the operating driving current of the at least one illumination source;

and

the second electrical parameter is a voltage corresponding to the predetermined driving current for the at least one illumination source.

6. A method according to claim 4, wherein

the first electrical parameter is a feedback current corresponding to the operating driving current of the at least one illumination source;

and

the second electrical parameter is a current corresponding to the predetermined driving current for the at least one illumination source.

7. A method according to claim 4, wherein the digital reference is stored in a memory.

8. A method according to claim 4, wherein the driving bias current corresponds to a difference between the first and second electrical parameters.

9. A method according to claim 4, wherein the display system is a liquid crystal display system.

10. A method according o claim 4, wherein the at least one illumination source includes at least one light-emitting diode.

13. A display system comprising:

a display panel having at least one illumination source;

a programmable interface configured to store a digital reference programmable by a user;

a digital-to-analog converter configured to convert the digital reference into a first electrical parameter;

a comparator configured to compare the first electrical parameter with a second electrical parameter corresponding to an operating driving current of the at least one illumination source, and generate a driving bias current; and

a current regulator configured to regulate the operating driving current of the at least one illumination source according to the driving bias current, wherein the driving bias current corresponds to a difference between the first and second electrical parameters.

14. A display system according to claim 13, wherein the second electrical parameter is obtained by measurement of the operating driving current flowing through the illumination source.

15. A display system according to claim 13, wherein the programmable interface is an inter-integrated circuit serial interface.

16. A display system according to claim 13, wherein the programmable interface is three-wire serial interface.