Control system for fluorescent light fixture

• US 8,531,107 B2
• Filed: 02/20/2012
• Issued: 09/10/2013
• Est. Priority Date: 04/18/2005
• Status: Expired due to Fees

• Current Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Sutardja, Sehat
• Primary Examiner(s): A, Minh D
• Application Number:
  US13/400,269
• Publication Number:
  US 20120146551A1
• Time in Patent Office: 568 Days
• Field of Search: 315/291, 315/307, 315/308, 315/309, 315/224, 315/200.R, 315/209.R, 315/32, 315/50, 315/112
• US Class Current: 315/50
• CPC Class Codes: H05B 41/2856 against internal abnormal circuit conditions
• CPC Class Codes: H05B 41/2986 against internal abnormal circuit conditions

Abstract

A circuit includes a component connected (i) to a rectifier, and (ii) between electrodes of a lamp. The electrodes include a first electrode and a second electrode. A control module is in communication with the rectifier and is configured to receive a temperature signal from a temperature sensor. The temperature signal is indicative of a temperature of the component. The control module is also configured to decrease current to the electrodes for a predetermined period when the temperature of the component is greater than a first predetermined temperature. The control module is further configured to increase the current to the electrodes when the predetermined period expires and independent of the temperature of the component.

Claims

1. A circuit comprising:

a component connected (i) to a rectifier, and (ii) between a plurality of electrodes of a lamp, wherein the plurality of electrodes comprises a first electrode and a second electrode; and

a control module in communication with the rectifier and configured to

receive a temperature signal from a temperature sensor, wherein the temperature signal is indicative of a temperature of the component,

while the lamp is ON, decrease current to the plurality of electrodes for a predetermined period and in response to the temperature of the component being greater than a predetermined temperature, and

increase the current to the plurality of electrodes in response to the predetermined period expiring and independent of the temperature of the component.

2. The circuit of claim 1, further comprising the rectifier, wherein:

the rectifier is configured to receive power from an alternating current source; and

the control module is configured to adjust the current to the plurality of electrodes based on (i) a power output of the rectifier, and (ii) the temperature of the component.

3. The circuit of claim 1, wherein the control module is configured to increase the current to the plurality of electrodes in response to the temperature of the component being less than the predetermined temperature.

4. The circuit of claim 1, wherein the control module is configured to increase the current to the plurality of electrodes (i) in response to the temperature of the component being greater than the predetermined temperature, and (ii) subsequent to the predetermined period expiring.

5. The circuit of claim 1, wherein the control module is configured to, in response to the temperature of the component being greater than the predetermined temperature, decrease the current to the plurality of electrodes subsequent to the increasing of the current to the plurality of electrodes.

6. The circuit of claim 1, wherein the control module is configured to:

switch on the lamp;

switch off the lamp in response to the temperature of the component being greater than the predetermined temperature;

start a timer in response to the lamp being switched off, wherein the timer indicates whether the predetermined period has expired; and

switch the lamp on according to the timer and in response to the predetermined period expiring.

7. The circuit of claim 1, further comprising the rectifier, wherein:

the rectifier comprises a first input and a first output;

the control module comprises a second input and a second output; and

terminals of the component are connected (i) between the first input and the first output, and (ii) between the second input and the second output.

8. The circuit of claim 1, further comprising transistors connected between the first electrode and the second electrode,

wherein the control module controls operating states of the transistors to adjust the current to the first electrode and the second electrode.

9. The circuit of claim 1, further comprising:

a first capacitance connected between the control module and the first electrode;

a second capacitance connected between the control module and the second electrode; and

a third capacitance connected between the first electrode and the second electrode.

10. The circuit of claim 9, wherein the first electrode, the second electrode, the first capacitance, the second capacitance, and the third capacitance are connected in series.

11. The circuit of claim 1, wherein the component comprises an electrolytic capacitance.

12. A circuit comprising:

a component connected (i) to a rectifier, and (ii) between a plurality of electrodes of a lamp, wherein the plurality of electrodes comprises a first electrode and a second electrode;

transistors connected between the first electrode and the second electrode; and

a control module in communication with the rectifier and configured to

receive a temperature signal from a temperature sensor, wherein the temperature signal is indicative of a temperature of the component,

decrease current to the plurality of electrodes for a predetermined period when the temperature of the component is greater than a predetermined temperature,

increase the current to the plurality of electrodes when the predetermined period expires and independent of the temperature of the component, and

control operating states of the transistors to adjust the current to the first electrode and the second electrode,

wherein the control module comprises, an input, a first output, a second output and a third output, and

wherein the transistors comprise

a first transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal is connected to the input of the control module, and wherein the control terminal is connected to the first output of the control module; and

a second transistor having a first terminal, a second terminal, and a control terminal, wherein the first terminal of the second transistor is connected to the second terminal of the first transistor, wherein the second terminal of the second transistor is connected to the third output of the control module, and wherein the control terminal is connected to the second output of the control module.

13. The circuit of claim 12, wherein:

the first terminal of the first transistor is connected to an output of the rectifier; and

the second terminal of the second transistor is connected to an input of the rectifier.

14. The circuit of claim 12, further comprising a capacitance having a first terminal and a second terminal, wherein:

the first terminal of the capacitance is connected to the first terminal of the first transistor;

the second terminal of the capacitance is connected to the second terminal of the first transistor; and

the capacitance is connected (i) between the first electrode and the second electrode, and (ii) between the input of the control module and the first electrode.

15. The circuit of claim 12, further comprising an inductance connected:

between the first electrode and the second terminal of the first transistor;

between the first electrode and the first terminal of the second transistor; and

between the first electrode and a terminal of the control module.

16. The circuit of claim 12, further comprising:

a capacitance connected between the first electrode and the input of the control module; and

an inductance connected between the first electrode and the capacitance.

17. A method comprising:

operating a control module based on an output of a rectifier;

receiving a temperature signal from a temperature sensor by the control module, wherein the temperature signal is indicative of a temperature of a component, wherein the component is connected (i) to the rectifier, and (ii) between a plurality of electrodes of a lamp, wherein the plurality of electrodes include a first electrode and a second electrode;

while the lamp is ON and via the control module, decreasing current to the plurality of electrodes for a predetermined period and in response to the temperature of the component being greater than a predetermined temperature; and

via the control module, increasing the current to the plurality of electrodes in response to the predetermined period expiring and independent of the temperature of the component.

18. The method of claim 17, further comprising increasing the current to the plurality of electrodes in response to the temperature of the component being less than the predetermined temperature.

19. The method of claim 17, further comprising:

increasing the current to the plurality of electrodes (i) in response to the temperature of the component being greater than the predetermined temperature, and (ii) subsequent to the predetermined period expiring; and

subsequent to the increasing of the current, decreasing the current to the plurality of electrodes in response to the temperature of the component being greater than the predetermined temperature.

20. The method of claim 17, further comprising:

switching on the lamp;

switching off the lamp in response to the temperature of the component being greater than the predetermined temperature;

starting a timer in response to the lamp being switched off, wherein the timer indicates whether the predetermined period has expired; and

switching the lamp on according to the timer and in response to the predetermined period expiring.