LED controller and control method thereof

• US 20060091826A1
• Filed: 05/20/2005
• Published: 05/04/2006
• Est. Priority Date: 10/28/2004
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Premier Image Technology Limited (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Chen, Cheng Fang
• Granted Patent: US 7,327,098 B2
• Time in Patent Office: Days
• US Class Current: 315/291
• CPC Class Codes: H05B 45/12 using optical feedback

Abstract

A LED controller and a control method thereof are disclosed. The LED controller can generate a control signal to drive a LED, measure a luminous intensity value of the LED, and selectively adjust the control signal according to the measured value to dynamically adjust the luminous intensity. Besides, a simple design of driving circuit is applied to achieve an effect of dynamically adjusting the current of the LED.

Claims

1. A light-emitting diode (LED) controller comprising:

a sensing unit for sensing a luminous intensity of a LED and outputting a corresponding sensing signal;

a control unit, coupled to the sensing unit, for outputting a control signal according to the sensing signal; and

a driving unit, coupled to the control unit, for driving the LED according to the control signal.

2. The LED controller of claim 1, wherein the control unit determines whether the luminous intensity reaches a predetermined value according to the sensing signal.

3. The LED controller of claim 2, wherein a color of the LED is one of red, green and blue, and the predetermined value is generated according to a CIE colorimetry.

4. The LED controller of claim 2, wherein the control unit comprises:

an analog-to-digital converter (ADC) for converting the sensing signal into a digital response value of the luminous intensity; and

a microprocessor, coupled to the ADC, for determining whether the luminous intensity reaches the predetermined value according to the response value.

5. The LED controller of claim 1, wherein the control unit determines whether the LED is aging by comparing the outputted control signal and the subsequent sensing signal.

6. The LED controller of claim 1, wherein the control signal comprises a pulse width modulation (PWM) signal, and the driving unit adjusts the luminous intensity according to the PWM signal.

7. The LED controller of claim 1, wherein the control signal comprises a driving signal for driving the LED.

8. The LED controller of claim 7, wherein the driving unit generates a feedback signal, and the control unit outputs the driving signal according to the feedback signal.

9. A light-emitting diode (LED) control method comprising:

generating a control signal to drive a LED;

sensing a luminous intensity value of the LED; and

selectively adjusting the control signal according to the luminous intensity value.

10. The LED control method of claim 9, wherein the adjusting step comprises:

determining whether the luminous intensity value reaches a predetermined value.

11. The LED control method of claim 10, wherein a color of the LED is one of red, green and blue, and the predetermined value is determined according to a CIE colorimetry.

12. The LED control method of claim 10, further comprising:

repeatedly executing the sensing step and the adjusting step until the luminous intensity value reaches the predetermined value.

13. The LED control method of claim 10, wherein the adjusting step further comprises:

determining whether the LED is aging when the luminous intensity value reaches the predetermined value.

14. The LED control method of claim 13, wherein the adjusting step further comprises:

repeatedly executing the sensing step and the adjusting step after a first time if the LED is aging; and

repeatedly executing the sensing step and the adjusting step after a second time if the LED is not aging;

wherein the first time is shorter than the second time.

15. The LED control method of claim 13, wherein the aging-determining step comprises comparing the control signal and the luminous intensity value.

16. A light-emitting diode (LED) driving device comprising:

a LED unit for emitting a luminous intensity according to a corresponding driving signal; and

a first adjusting unit for generating an adjusting signal to the LED unit according to a pulse width modulation (PWM) signal, and adjusting the luminous intensity according to the adjusting signal.

17. The LED driving device of claim 16, wherein the first adjusting unit comprises:

an operational amplifier with a non-inverting input, an inverting input and an output, wherein the inverting input receives the PWM signal and the non-inverting input is coupled to ground;

a first resistor coupled between the inverting input and the output; and

a second resistor coupled to the output and the LED unit.

18. The LED driving device of claim 16, wherein the LED unit comprises:

a LED for receiving the driving signal; and

a first switch coupled to the LED and switching according to a switch signal.

19. The LED driving device of claim 18, further comprising:

a second adjusting unit for outputting a feedback signal used to determine the driving signal.

20. The LED driving device of claim 19, wherein the second adjusting unit comprises:

a power source;

a variable resistor coupled to the power source and providing the feedback signal; and

a second switch coupled to the power source and switching according to the switch signal, wherein the first and second switches are not connected simultaneously.