Method for protecting a lamp circuit and related wiring

• US 7,755,293 B2
• Filed: 06/19/2008
• Issued: 07/13/2010
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Yazaki North America Incorporated (Yazaki Corporation)
• Original Assignee: Yazaki North America Incorporated (Yazaki Corporation)
• Inventors: Moore, Daniel, Li, Kang
• Primary Examiner(s): Owens; Douglas W
• Assistant Examiner(s): Le; Tung X
• Application Number:
  US12/141,970
• Publication Number:
  US 20090315465A1
• Time in Patent Office: 754 Days
• Field of Search: 315/77, 315/82, 315/224, 315/291, 315/294, 315/299, 315/307, 315/308, 315/312, 315/320, 315/324, 307/10.1, 307/10.8, 324/500, 324/504
• US Class Current: 315/77
• CPC Class Codes: H05B 39/00 Circuit arrangements or apparatus for operating incandescent light sources structurally associated with the incandescent lamps H01K1/62
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A method for controlling a lamp circuit that includes: setting a first voltage threshold and a first time window within a control circuit corresponding to a characteristic of a first lamp type; providing a first signal through the lamp circuit to start a first time interval and create a first test voltage; comparing the first test voltage to the first voltage threshold; and operating a switch to couple an output of the lamp circuit to a source of electrical power if the first test voltage is greater than or equal to the first voltage threshold before the first time interval exceeds the first time window.

Claims

1. A method for controlling a lamp circuit, the method comprising:

setting a first voltage threshold and a first time window within a control circuit corresponding to a characteristic of a first lamp type;

providing a first signal through the lamp circuit to start a first time interval and create a first test voltage;

comparing the first test voltage to the first voltage threshold; and

operating a switch to couple an output of the lamp circuit to a source of electrical power if the first test voltage is greater than or equal to the first voltage threshold before the first time interval exceeds the first time window.

2. The method of claim 1, further comprising:

providing an indicate signal within a control circuit corresponding to a state in which the lamp circuit is operating; and

changing a state of the indicate signal if the first test voltage is not greater than or equal to the first voltage threshold before the first time interval exceeds the first time window.

3. The method of claim 1, wherein the first test voltage will not reach the first voltage threshold before the first time interval exceeds the first time window if a lamp that is coupled to the lamp circuit is a second lamp type or a short circuit condition exists between the output of the lamp circuit and an electrical ground.

4. The method of claim 1, further comprising providing a second signal through the lamp circuit to operate a second switch such that the second switch couples the lamp circuit to the source of electrical power.

5. The method of claim 4, further comprising toggling the second signal to identify a short circuit condition between the output of the lamp circuit and an electrical ground.

6. The method of claim 1, wherein a first circuit protection device is disposed in a first path that couples the source of electrical power, the first switch and the output of the lamp circuit, and a second circuit protection device is disposed in a second path that couples the source of electrical power, the second switch and the output of the lamp circuit.

7. The method of claim 6, wherein the second circuit protection device is configured to conduct more current than the first circuit protection device.

8. The method of claim 6, wherein the first circuit protection device is disposed between a device that senses the first test voltage and the output of the lamp circuit and wherein the second circuit protection is disposed between the source of electrical power and the second switch.

9. The method of claim 6, wherein the first and second circuit protection devices are fuses.

10. The method of claim 1, wherein providing the first signal through the lamp circuit starts a second time interval and wherein the method further comprises:

generating a second test voltage; and

operating a second switch to couple the output of the lamp circuit to the source of electrical power if the second test voltage is greater than or equal to a second voltage threshold before the second time interval exceeds a second time window.

11. The method of claim 10, wherein a first circuit protection device is disposed between the first capacitor and the output of the lamp circuit and a second circuit protection device is disposed between the source of electrical power and the second switch and wherein the second circuit protection device is configured to conduct more current than the first circuit protection device, wherein a first circuit protection device is disposed in a first path that couples the source of electrical power, the first switch and the output of the lamp circuit, and a second circuit protection device is disposed in a second path that couples the source of electrical power, the second switch and the output of the lamp circuit.

12. The method of claim 11, wherein the first and second current protection devices are fuses.

13. The method of claim 10, wherein the first and second switches are selected from a group consisting of relays and solid state switches.

14. The method of claim 10, wherein the method further comprises:

creating a third test voltage;

coupling a resistive short circuit to the output of the lamp circuit; and

de-energizing the second switch after the third test voltage exceeds a predetermined third voltage threshold.

15. A method for controlling a lamp circuit, the method comprising:

setting a first voltage threshold within a control circuit corresponding to a characteristic of a first lamp type;

providing a first signal to a lamp;

comparing a measured voltage drop across the lamp to the first voltage threshold to determine whether the lamp is the first lamp type; and

activating a first circuit portion of the control circuit to couple a power source to the output of the lamp circuit if the lamp is the first type of lamp.

16. The method of claim 15, wherein if the lamp is not the first type of lamp, the first circuit portion of the control circuit activates a second circuit portion of the control circuit to couple the power source to the output of the lamp circuit.

17. The method of claim 16, further comprising:

determining whether the output of the lamp circuit is coupled to a resistive short circuit; and

opening the first and second switching elements to decouple the power source from the output of the lamp circuit.

18. The method of claim 15, wherein the lamp circuit includes a first switching element, which is controlled by the first circuit portion, and a second switching element, which is controlled by the second circuit portion, each of the first and second switching elements having a first terminal, which is coupled to the source of electrical power, and a second terminal, wherein a first circuit protection device is electrically coupled to the first switching element and wherein a second circuit protection device is electrically coupled to the second switching element.

19. The method of claim 18, wherein the second circuit protection device is configured to conduct more current than the first circuit protection device.

20. The method of claim 18, wherein the first and second circuit protection devices are fuses.

21. The method of claim 15, further comprising:

toggling a second signal to a second circuit portion of the control circuit to determine whether the lamp is a second lamp type; and

activating the second circuit portion to provide power from the power source to the output of the lamp circuit if the lamp is the second type of lamp.

22. The method of claim 21, further comprising determining whether the output of the lamp circuit is coupled to a resistive short circuit.