LED tube lamp and power supply module applicable thereto
A power supply module is applicable to an LED tube lamp adapted to install on a lamp socket, and having an electric shock protection function, the LED tube lamp including a lamp tube, two end caps, each having a first external connection terminal, and each coupled to a respective end of the lamp tube, the first connection terminals of the two end caps for receiving an external signal, and an LED module configured for emitting light. The power supply module includes: a rectifying circuit, coupled to the first external connection terminals of the end caps and the LED module, for rectifying a received signal to produce a rectified signal; a filtering circuit, coupled to the rectifying circuit and the LED module, for filtering the rectified signal to produce a filtered signal; a transistor configured to be switched according to a control signal; an electric shock protection controller for detecting whether an electric shock risk has occurred, and configured to cause a current to be conducted in the detection path for generating the detection result.
1. A light-emitting diode (LED) tube lamp adapted to install on a lamp socket and having electric shock protection function protecting a user from electric shock when installing the LED tube lamp into the lamp socket, the LED tube lamp comprising:
a lamp tube;
two end caps, each having a first external connection terminal, and each coupled to a respective end of the lamp tube, the first external connection terminals of the two end caps for receiving an external signal;
a rectifying circuit, coupled to the first external connection terminals of the end caps, for rectifying a received signal to produce a rectified signal;
a filtering circuit, coupled to the rectifying circuit, for filtering the rectified signal to produce a filtered signal;
an LED module coupled to the rectifying circuit and the filtering circuit and configured for emitting light;
an electric shock protection controller, configured to determine whether to limit a current on a power loop formed between the first external connection terminals to less than a predefined value according to a detection result;
a transistor, coupled to the power loop and configured to be switched according to a detection control signal; and
one or more impedance devices, coupled to the transistor, which impedance devices and the transistor form a detection path coupled between the power loop and a ground terminal,
wherein the electric shock protection controller is configured to cause a current to be conducted in the detection path for detecting an installation state between the LED tube lamp and the lamp socket and generating the detection result.
2. The LED tube lamp according to claim 1 , wherein detecting the installation state is for detecting whether an electric shock risk has occurred, and the electric shock protection controller is configured to turn a switch circuit, connected to the power loop, on or off according to the detection result.
3. The LED tube lamp according to claim 1 , configured such that a driving voltage is provided to the electric shock protection controller when power is provided to at least one of the two end caps of the LED tube lamp, and the electric shock protection controller starts to work when the driving voltage reaches a defined level.
4. The LED tube lamp according to claim 1 , wherein:
the one or more impedance devices include a resistor having a first end connected to the ground terminal; and
the transistor has a first terminal connected to the power loop, a second terminal coupled to a second end of the resistor, and a control terminal, wherein the detection path includes the resistor and the transistor.
5. The LED tube lamp according to claim 1 , wherein the electric shock protection controller includes a control circuit configured to produce a control signal according to a detection result signal indicating the installation state, and a detection determining circuit coupled to the control circuit and configured to detect a signal feature on the detection path and produce the detection result signal.
6. The LED tube lamp according to claim 5 , wherein:
the one or more impedance devices include a resistor having a first end connected to the ground terminal; and
the transistor has a first terminal connected to the power loop via a first node, a second terminal connected to a second end of the resistor via a second node, and a control terminal for receiving the detection control signal,
wherein the detection determining circuit detects the signal feature on at least one of the first and the second nodes.
7. The LED tube lamp according to claim 6 , wherein the detection control signal is a pulse signal whose pulse width is between 10 μs and 1 ms.
8. The LED tube lamp according to claim 6 , wherein the detection control signal is a pulse signal whose pulse width is between 1 μs and 100 μs.
9. The LED tube lamp according to claim 6 , wherein the electric shock protection controller includes a detection pulse generating module for generating the detection control signal, and the detection control signal comprises at least two pulses for performing two detections.
10. The LED tube lamp according to claim 9 , wherein at least one of the pulses is not generated when the logic level of the external signal is substantially zero.
11. The LED tube lamp according to claim 10 , wherein there is an interval with a defined time between the pulses.
12. The LED tube lamp according to claim 6 , wherein the signal level of a voltage on the at least one of the first and the second nodes is determined by voltage division among the resistor, the transistor, and an impedance of a human body.
13. The LED tube lamp according to claim 5 , wherein the control circuit outputs the control signal with a high level when a voltage on the detection path is higher than a reference voltage, and outputs the control signal with a low level when the voltage on the detection path is lower than the reference voltage.
14. The LED tube lamp according to claim 5 , wherein the detection determining circuit includes:
a comparator, configured to sample a voltage signal on the detection path, compare the signal level of the voltage signal with a reference voltage, and output the detection result signal.
15. The LED tube lamp according to claim 14 , wherein the control circuit includes:
a detection result latching circuit, connected to the comparator to receive the detection result signal, and configured to latch the detection result according to the detection result signal and to output a detection result latching signal as the control signal.
16. The LED tube lamp according to claim 1 , wherein the LED module is configured to be driven based on a driving signal for emitting light, and the LED tube lamp further comprises a driving circuit coupled to the filtering circuit and the LED module, for performing power conversion and producing the driving signal.
17. The LED tube lamp according to claim 1 , wherein the electric shock protection controller, the transistor, and the one or more impedance devices are part of an installation detection module for detecting an installation state between the LED tube lamp and the lamp socket.
18. A power supply module applicable to an LED tube lamp adapted to install on a lamp socket, and having electric shock protection function, the LED tube lamp including a lamp tube; two end caps, each having a first external connection terminal, and each coupled to a respective end of the lamp tube, the first external connection terminals of the two end caps for receiving an external signal; and an LED module configured for emitting light, the power supply module comprising:
a rectifying circuit, coupled to the first external connection terminals of the end caps and the LED module, for rectifying a received signal to produce a rectified signal;
a filtering circuit, coupled to the rectifying circuit and the LED module, for filtering the rectified signal to produce a filtered signal;
a switch circuit configured to be switched according to a control signal;
an electric shock protection controller coupled to the switch circuit, for detecting whether an electric shock risk has occurred, and configured to turn the switch circuit on or off according to the detection result; and
one or more impedance devices, which impedance devices and at least one electric component of the electric shock protection controller form a detection path,
wherein the electric shock protection controller is configured to cause a current to be conducted in the detection path for generating the detection result.
19. The power supply module according to claim 18 , wherein the LED module is configured to be driven based on a driving signal for emitting light, and the power supply module further comprises a driving circuit coupled to the filtering circuit and the LED module, for performing power conversion and producing the driving signal.
20. The power supply module according to claim 18 , wherein the electric shock protection controller includes a control circuit configured to produce the control signal according to a detection result signal indicating the installation state, and further comprising a detection determining circuit coupled to the control circuit and configured to detect a signal feature on the detection path and produce the detection result signal.
21. The power supply module according to claim 20 , wherein the impedance devices include a resistor having a first end connected to a ground terminal; and the electric shock protection controller includes:
a transistor, having a first terminal connected to the rectifying circuit via a first node, a second terminal connected to a second end of the resistor via a second node, and a control terminal for receiving a detection control signal,
wherein the detection determining circuit detects the signal feature on at least one of the first and the second nodes.
22. The power supply module according to claim 21 , wherein the detection control signal is a pulse signal whose pulse width is between 10 μs and 1 μms.
23. The power supply module according to claim 21 , wherein the detection control signal is a pulse signal whose pulse width is between 1 μs and 100 μs.
24. The power supply module according to claim 21 , wherein the electric shock protection controller includes a detection pulse generating module for generating the detection control signal, and the detection control signal comprises at least two pulses for performing two detections.
25. The power supply module according to claim 24 , wherein at least one of the pulses is not generated when the logic level of the external signal is substantially zero.
26. The power supply module according to claim 24 , wherein there is an interval with a defined time between the pulses.
27. The power supply module according to claim 21 , wherein the signal level of a voltage on the detection path is determined by voltage division among the resistor, the transistor, and an impedance of a human body.
28. The power supply module according to claim 20 , wherein the control circuit pulls a control terminal of the switch circuit to a high level when a voltage on the detection path is higher than a reference voltage, and pulls the control terminal of the switch circuit to a low level when the voltage on the detection path is lower than the reference voltage.
29. The power supply module according to claim 18 , configured such that a driving voltage is provided to the electric shock protection controller when power is provided to at least one of the two end caps of the LED tube lamp, and the electric shock protection controller starts to work when the driving voltage reaches a defined level.
30. The power supply module according to claim 18 , wherein the electric shock protection controller, the switch circuit, and the one or more impedance devices are part of an installation detection module for detecting whether an electric shock risk has occurred.
31. A power supply method for a ballast-bypass type LED tube lamp, comprising:
receiving an AC signal, without the AC signal passing through a ballast, from respective ends of the LED tube lamp;
rectifying and filtering the AC signal to produce a filtered signal;
converting the filtered signal into a driving signal by a power conversion means;
providing the driving signal to an LED module of the LED tube lamp for emitting light;
detecting a signal feature on a detection path on the LED tube lamp and generating an installation detection result; and
limiting a current on a current path of the LED tube lamp when the installation detection result indicates a risk of electric shock exists.
32. The power supply method for a ballast-bypass type LED tube lamp according to claim 31 , further comprising:
providing a detection path circuit in the LED tube lamp for forming the detection path.
33. The power supply method for a ballast-bypass type LED tube lamp according to claim 32 , wherein the detection path circuit consists of electronic components included in the current path.
34. The power supply method for a ballast-bypass type LED tube lamp according to claim 32 , wherein at least one electronic element of the detection path circuit is different from electronic elements included in the current path.
35. The power supply method for a ballast-bypass type LED tube lamp according to claim 34 , wherein the detection path circuit includes:
a resistor, having a first end connected to a ground terminal; and
a transistor, having a first terminal connected to the current path, a second terminal connected to a second end of the resistor, and a control terminal for receiving a detection control signal.