LIGHT SOURCE DRIVING DEVICE

• US 20080246420A1
• Filed: 04/03/2008
• Published: 10/09/2008
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: Ger, Chih-Chan, Chen, Wen-Lin, Mi, Tzu-Chiang
• Granted Patent: US 7,629,752 B2
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: H05B 41/3921 with possibility of light intensity variations
• CPC Class Codes: H05B 41/3927 by pulse width modulation H05B41/3922 takes precedence

Abstract

A light source driving device is for driving a plurality of light sources of a light source module (12), and comprises an inverter circuit (11), a current sampling circuit (13) and a PWM controller (14). The inverter circuit converts a received DC signal to an electrical signal adapted for driving the light sources. The current sampling circuit for sampling current flowing through the inverter circuit, comprises an impedance detecting component (Z₁₁) and an amplifying circuit (132), the impedance detecting component detects the current from the inverter circuit, the amplifying circuit is connected to the impedance detecting component for amplifying the current signal. The PWM controller is connected to the current sampling circuit for receiving the amplified current signal output from the current sampling circuit, and generating a control signal to the inverter circuit to control output thereof.

Claims

1. A light source driving device is for driving a plurality of light sources of a light source module, comprising:

an inverter circuit, for converting a received DC signal to an electrical signal adapted for driving the light sources;

a current sampling circuit, for sampling current flowing through the inverter circuit, the current sampling circuit comprising;

an impedance detecting component, for detecting current from the inverter circuit; and

an amplifying circuit, connected to the impedance detecting component for amplifying the current signal; and

a PWM controller, connected to the current sampling circuit, for receiving the amplified current signal output from the current sampling circuit, and generating a control signal to the inverter circuit to control output thereof.

2. The light source driving device of claim 1, further comprising a first filter circuit connected to the inverter circuit.

3. The light source driving device of claim 2, wherein the current sampling circuit is disposed between the first filter circuit and the inverter circuit.

4. The light source driving device of claim 1, wherein the amplifying circuit comprising:

an amplifier, including a positive electrode input, a negative electrode input and an output;

a first impedance component, one end of thereof being connected to the negative electrode input of the amplifier, and the other end thereof being connected to one end of the impedance detecting component; and

a second impedance component, connected between the negative electrode input and the output of the amplifier.

5. The light source driving device of claim 4, wherein the current sampling circuit comprises a second filter circuit connected between the positive electrode input of the amplifier and the other end of the impedance detecting component.

6. The light source driving device of claim 5, wherein the second filter circuit comprising:

a first resistor, one end thereof being connected to the other end of the impedance detecting component;

a first capacitor, connected between the positive electrode input of the amplifier and ground; and

a second resistor, connected to the first capacitor in parallel.

7. The light source driving device of claim 4, wherein the amplifying circuit comprises a third resistor with one end being connected to the output of the amplifier and the other end being defined as the output of the current sampling circuit.

8. The light source driving device of claim 7, wherein the current sampling circuit comprises a switch component comprising an input, a first output and a second output, wherein the input is controlled by a PWM signal, the second output is grounded.

9. The light source driving device of claim 8, further comprises a fourth resistor, disposed between the first output of the switch component and the other end of the third resistor.

10. The light source driving device of claim 4, wherein the second impedance component comprising:

a fifth resistor, disposed between the negative electrode input and output of the amplifier;

a second capacitor; and

a sixth resistor, connected to the second capacitor in series and both connected to the fifth resistor in parallel.

17. The light source driving device of claim 1, wherein the current sampling circuit comprising:

a fourth resistor;

a switch component comprising an input, a first output and a second output, wherein the input is controlled by a PWM signal, the first output is connected to the PWM controller by way of the fourth resistor, the second output is grounded.

18. The light source driving device of claim 17, wherein the second impedance component comprising:

a fifth resistor, disposed between the negative electrode input and output of the amplifier;

a second capacitor; and

a sixth resistor, connected to the second capacitor in series and connected to the fifth resistor in parallel.

11. A light source driving device, connected to a DC power source, for converting a DC signal provided by the DC power source to an electrical signal to drive a plurality of light sources, wherein the DC power source has a high voltage end and a low voltage end, the light source driving device comprising:

an inverter circuit, connected between the high voltage end and the low voltage end of the DC power source, for converting the DC signal to the electrical signal adapted for driving the light sources;

a current sampling circuit, connected between the inverter circuit and the low voltage end of the DC power source, for sampling current flowing through the inverter circuit and generating an output signal; and

a PWM controller, connected between the current sampling circuit and the inverter circuit, for receiving the amplified current signal output from the current sampling circuit, and generating a control signal to the inverter circuit to control output thereof.

12. The light source driving device of claim 11, further comprises a first filter circuit connected between the high voltage end and the low voltage end of the DC power source.

13. The light source driving device of claim 12, wherein the current sampling circuit comprising:

an impedance detecting component, the input being connected to the inverter circuit, and the output being connected to the low voltage end of the DC power source; and

an amplifying circuit, connected to the output of the impedance detecting component for amplifying the current signal.

14. The light source driving device of claim 13, wherein the amplifying circuit comprising:

an amplifier, including a positive electrode input, a negative electrode input and an output;

a first impedance component, one end of the first impedance component being connected to the negative electrode input, and the other end thereof being connected to one end of the impedance detecting component; and

a second impedance component, connected between the negative electrode input and the output of the amplifier.

15. The light source driving device of claim 14, wherein the current sampling circuit comprises a second filter circuit connected between the positive electrode input of the amplifier and the other end of the impedance detecting component.

16. The light source driving device of claim 15, wherein the second filter circuit comprising:

a first resistor, one end thereof being connected to the other end of the impedance detecting component;

a first capacitor, connected between the positive electrode input of the amplifier and ground; and

a second resistor, connected to the first capacitor in parallel.

19. The light source driving device of claim 13, wherein the first filter circuit is disposed between the high voltage end of the DC power source and the input of the impedance detecting component.

20. The light source driving device of claim 13, wherein the first filter circuit is disposed between the high voltage end of the DC power source and the output of the impedance detecting component.