Method for driving LED tube lamp

• US 10,690,299 B2
• Filed: 06/26/2019
• Issued: 06/23/2020
• Est. Priority Date: 12/09/2015
• Status: Active Grant

• Current Assignee: Jiaxing Super Lighting Electric Appliance Co., Ltd.
• Original Assignee: Jiaxing Super Lighting Electric Appliance Co., Ltd.
• Inventors: Xiong, Aiming, Liu, Xintong
• Primary Examiner(s): Tran, Anh Q
• Application Number:
  US16/452,857
• Publication Number:
  US 20190346088A1
• Time in Patent Office: 363 Days
• Field of Search: None
• CPC Class Codes: F21K 9/272 Details of end parts, i.e. the parts that connect the light source to a fitting; Arrangement of components within end parts F21K9/278 takes precedence
• CPC Class Codes: F21K 9/275 Details of bases or housings, i.e. the parts between the light-generating element and the end caps; Arrangement of components within bases or housings F21K9/278 takes precedence
• CPC Class Codes: F21K 9/278 Arrangement or mounting of circuit elements integrated in the light source
• CPC Class Codes: F21V 15/015 Devices for covering joints between adjacent lighting devices; End coverings
• CPC Class Codes: F21V 23/003 the elements being electronics drivers or controllers for operating the light source, e.g. for a LED array
• CPC Class Codes: F21V 23/005 the substrate is supporting also the light source
• CPC Class Codes: F21V 23/02 the elements being transformers, impedances or power supply units, e.g. a transformer with a rectifier
• CPC Class Codes: F21V 23/023 Power supplies in a casing F21V23/003 takes precedence
• CPC Class Codes: F21V 25/02 coming into action when lighting device is disturbed, dismounted, or broken
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 3/061 the material being glass
• CPC Class Codes: F21Y 2103/10 comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/32 Pulse-control circuits
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/345 Current stabilisation; Maintaining constant current
• CPC Class Codes: H05B 45/36 Circuits for reducing or suppressing harmonics, ripples or electromagnetic interferences [EMI]
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 : using buck topology
• CPC Class Codes: H05B 45/38 : using boost topology
• CPC Class Codes: H05B 47/26 : Circuit arrangements for protecting against earth faults
• CPC Class Codes: H05K 1/00 : Printed circuits
• CPC Class Codes: H05K 1/14 : Structural association of two or more printed circuits providing electric connection to or between printed circuits H05K1/11, H01R12/00
• CPC Class Codes: H05K 1/189 : characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2201/09027 : Non-rectangular flat PCB, e.g. circular
• CPC Class Codes: H05K 2201/10106 : Light emitting diode [LED]
• 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 driving an LED tube lamp includes providing a rectifying circuit for receiving an AC supply signal from a rectifying input side, wherein the AC supply signal has frequency of 50 Hz or 60 Hz when the LED tube lamp operates in a ballast-bypass mode, providing a filtering circuit electrically connected to the rectifying circuit, providing a driving circuit electrically connected to the filtering circuit and configured to generate a lamp driving signal to drive an LED module for emitting light, providing a circuit configured for forming a detection path between the rectifying input side and a ground terminal, causing a detection current with pulse waveform to flow through the detection path by turning on and cutting off the detection path, and generating a signal for indicating whether a foreign external impedance is electrically connected to the LED tube lamp in response to the detection current.

Claims

1. A method for driving a light-emitting diode (LED) tube lamp, comprising:

providing a rectifying circuit for receiving an AC supply signal from a rectifying input side, wherein the AC supply signal has frequency of 50 Hz or 60 Hz when the LED tube lamp operates in a ballast-bypass mode;

providing a filtering circuit electrically connected to the rectifying circuit;

providing a driving circuit electrically connected to the filtering circuit and configured to generate a lamp driving signal to drive an LED module for emitting light;

providing a circuit configured for forming a detection path between the rectifying input side and a ground terminal;

causing a detection current with pulse waveform to flow through the detection path by turning on and cutting off the detection path; and

generating a signal for indicating whether a foreign external impedance is electrically connected to the LED tube lamp in response to the detection current.

2. The method according to claim 1, wherein the foreign external impedance is a human body impedance or simulated/test human body impedance.

3. The method according to claim 1, further comprising:

generating a detection result signal according to the signal for indicating whether the foreign external impedance is electrically connected to the LED tube lamp; and

determining whether to disable the driving circuit according to the detection result signal.

4. The method according to claim 3, wherein the step of determining whether to disable the driving circuit according to the detection result signal comprises:

disabling the driving circuit when receiving the detection result signal indicating the foreign external impedance is electrically connected to the LED tube lamp; and

not disabling the driving circuit when receiving the detection result signal indicating the foreign external impedance is not electrically connected to the LED tube lamp.

5. The method according to claim 4, wherein the step of providing the driving circuit electrically connected to the filtering circuit and configured to generate the lamp driving signal to drive the LED module for emitting light comprises:

providing a controller having a power input terminal for receiving a bias voltage, wherein the power input terminal is electrically connected to a circuit configured to perform the step of determining whether to disable the driving circuit according to the detection result signal; and

providing a conversion circuit in the driving circuit, electrically connected to the filtering circuit and configured to perform power conversion, under control by the controller, to convert a signal received from the filtering circuit into the lamp driving signal.

6. The method according to claim 5, wherein the step of disabling the driving circuit when receiving the detection result signal indicating the foreign external impedance is electrically connected to the LED tube lamp comprises:

adjusting the bias voltage to a level that is not capable of enabling the controller.

7. The method according to claim 6, further comprising:

providing a transistor having a first terminal electrically connected to the power input terminal, a second terminal electrically connected to the ground terminal, and a control terminal receiving the detection result signal.

8. The method according to claim 7, wherein the step of adjusting the bias voltage to the level that is not capable of enabling the controller comprises:

electrically connecting the power input terminal to the ground terminal, by turning on the transistor, when receiving the detection result signal in a first state.

9. The method according to claim 5, wherein the step of not disabling the driving circuit when receiving the detection result signal indicating the foreign external impedance is not electrically connected to the LED tube lamp comprises:

not adjusting the bias voltage, so that the controller is capable of being enabled in response to the bias voltage.

10. The method according to claim 9, further comprising:

providing a transistor having a first terminal electrically connected to the power input terminal, a second terminal electrically connected to the ground terminal, and a control terminal receiving the detection result signal.

11. The method according to claim 10, wherein the step of not adjusting the bias voltage, so that the controller is capable of being enabled in response to the bias voltage comprises:

electrically disconnecting the power input terminal from the ground terminal, by turning off the transistor, when receiving the detection result signal in a second state.

12. The method according to claim 3, wherein the step of providing the driving circuit electrically connected to the filtering circuit and configured to generate the lamp driving signal to drive the LED module for emitting light comprises:

providing a controller having a power input terminal for receiving a bias voltage, wherein the power input terminal is electrically connected to a circuit configured to perform the step of determining whether to disable the driving circuit according to the detection result signal; and

providing a conversion circuit in the driving circuit, electrically connected to the filtering circuit and configured to perform power conversion, under control by the controller, to convert a signal received from the filtering circuit into the lamp driving signal.

13. The method according to claim 12, further comprising:

providing a transistor having a first terminal electrically connected to the power input terminal, a second terminal electrically connected to the ground terminal, and a control terminal receiving the detection result signal.

14. The method according to claim 13, further comprising:

electrically connecting the power input terminal to the ground terminal, by turning on the transistor, when receiving the detection result signal in a first state; and

electrically disconnecting the power input terminal from the ground terminal, by turning off the transistor, when receiving the detection result signal in a second state.

15. The method according to claim 1, further comprising:

generating a pulse signal to turn on and cut off the detection path.

16. The method according to claim 15, wherein the rectifying input side comprises a first rectifying input terminal and a second rectifying input terminal, and the step of providing the circuit configured for forming the detection path between the rectifying input side and the ground terminal comprises:

providing a first diode having an anode electrically connected to the first rectifying input terminal;

providing a second diode having an anode electrically connected to the second rectifying input terminal and a cathode electrically connected to a cathode of the first diode; and

providing a transistor having a first terminal electrically connected to the cathodes of the first and the second diodes, a second terminal electrically connected to the ground terminal, and a control terminal electrically connected to a circuit configured for performing the step of generating the pulse signal to turn on and cut off the detection path.

17. The method according to claim 16, further comprising:

providing a resistor electrically connected to the transistor in series, wherein the signal on the detection path is generated according to the detection current passing through the resistor.

18. The method according to claim 3, wherein the step of generating the detection result signal according to the signal for indicating whether the foreign external impedance is electrically connected to the LED tube lamp comprises:

sampling the signal on the detection path according to set time points, and generating a plurality of sample signals, respectively corresponding to the signal on the detection path at different set time points; and

generating the detection result signal according to the sample signals.

19. The method according to claim 18, wherein the step of sampling the signal on the detection path according to the set time points, and generating the sample signals, respectively corresponding to the signal on the detection path at different set time points comprises:

sampling the signal at a first time point to generate a first sample signal, wherein the first time point is inside of a pulse-on period of the detection current; and

sampling the signal at a second time point to generate a second sample signal, wherein the second time point is outside of the pulse-on period of the detection current.

20. The method according to claim 19, wherein the step of generating the detection result signal according to the sample signals comprises:

comparing at least two sample signals with each other and generating a comparison result; and

generating the detection result signal according to the comparison result.

21. The method according to claim 20, wherein the step of comparing at least two sample signals with each other and generating the comparison result comprises:

generating the comparison result having a first logic level when the levels of the first and the second sample signals are substantially equal to each other; and

generating the comparison result having a second logic level when the levels of the first and the second sample signals has a difference exceeding a preset value.

22. The method according to claim 18, wherein the step of generating the detection result signal according to the sample signals comprises:

comparing at least two sample signals with each other and generating a comparison result; and

generating the detection result signal according to the comparison result.