Led tube lamp
A power supply module is configured to provide, based on an external driving signal, a driving current for driving an LED tube lamp. The power supply module includes a detection path circuit, configured to establish a detection path which is capable of affecting an electrical signal on a power line of the power supply module when the detection path is turned on, and a driving circuit, electrically connected to the detection path circuit, and configured to produce the driving current based on the external driving signal. When the driving circuit is activated by receiving the external driving signal, the driving circuit enters into a first mode to detect whether a foreign external impedance is electrically connected to the LED tube lamp. When the foreign external impedance is detected, the driving circuit remains in the first mode, and when the foreign external impedance is not detected, the driving circuit enters into a second mode to produce the driving current. The driving circuit is further configured to obtain a dimming message from the electrical signal and adjust the magnitude of the driving current according to the dimming message when in the second mode.
1. A power supply module configured to provide, based on an external driving signal, a driving current for driving an LED tube lamp, comprising:
a detection path circuit, configured to establish a detection path which is capable of affecting an electrical signal on a power line of the power supply module when the detection path is turned on; and
a driving circuit, electrically connected to the detection path circuit, and configured to produce the driving current based on the external driving signal,
wherein when the driving circuit is activated by receiving the external driving signal, the driving circuit enters into a first mode to detect whether a foreign external impedance is electrically connected to the LED tube lamp,
wherein when the foreign external impedance is detected, the driving circuit remains in the first mode, and when the foreign external impedance is not detected, the driving circuit enters into a second mode to produce the driving current, and
wherein the driving circuit is further configured to obtain a dimming message from the electrical signal and adjust the magnitude of the driving current according to the dimming message when in the second mode.
2. The power supply module according to claim 1 , wherein the driving circuit comprises:
a driving controller, electrically connected to the detection path circuit for receiving the electrical signal; and
a conversion circuit, electrically connected to the driving controller and configured to produce the driving current in response to the control of the driving controller.
3. The power supply module according to claim 1 , further comprising:
a rectifying circuit, having input terminals for receiving the external driving signal and output terminals; and
a filtering circuit, having input terminals electrically connected to the output terminals of the rectifying circuit and output terminals electrically connected to the driving circuit.
4. The power supply module according to claim 3 , wherein the detection path circuit comprises:
a first diode, having an anode electrically connected to one of the input terminals of the rectifying circuit and a cathode;
a second diode, having an anode electrically connected to another one of the input terminals of the rectifying circuit and a cathode electrically connected to the cathode of the first diode; and
a transistor, having a first terminal electrically connected to the cathode of the first and the second diodes, a second terminal electrically connected to a ground terminal, and a control terminal configured to receive a pulse signal in the first mode.
5. The power supply module according to claim 3 , wherein the detection path circuit comprises:
a transistor, having a first terminal electrically connected to one of the output terminals of the rectifying circuit, a second terminal electrically connected to another one of the output terminals of the rectifying circuit, and a control terminal configured to receive a pulse signal in the first mode.
6. A method for determining whether a foreign external impedance is electrically connected to an LED tube lamp, comprising:
sampling a voltage on a detection path disposed in the LED tube lamp at a first point in time to obtain a first voltage level;
issuing, after the first point in time, a pulse signal to temporarily turn on the detection path;
sampling the voltage on the detection path at a second point in time to obtain a second voltage level, wherein the second point in time is within the period of the detection path being turned on; and
generating an indication for indicating whether the foreign external impedance is electrically connected to the LED tube lamp according to the first voltage level and the second voltage level.
7. The method according to claim 6 , wherein the step of generating a result for indicating whether the foreign external impedance is electrically connected to the LED tube lamp according to the first voltage level comprises:
calculating a difference between the first voltage level and the second voltage level;
comparing the difference with a set value;
generating the indication with a first logic level for indicating the foreign external impedance is electrically connected to the LED tube lamp when the difference is greater than the set value; and
generating the indication with a second logic level for indicating the foreign external impedance is not electrically connected to the LED tube lamp when the difference is not greater than the set value.
8. The method according to claim 6 , wherein the step of generating a result for indicating whether the foreign external impedance is electrically connected to the LED tube lamp according to the first voltage level comprises:
respectively comparing the first voltage level and the second voltage level with a set value;
generating the indication with a first logic level for indicating the foreign external impedance is electrically connected to the LED tube lamp when the first voltage level and the second voltage level are not greater than the set value; and
generating the indication with a second logic level for indicating the foreign external impedance is not electrically connected to the LED tube lamp when the first voltage level is not greater than the set value and the second voltage level is greater than the set value.
9. The method according to claim 6 , wherein the step of generating a result for indicating whether the foreign external impedance is electrically connected to the LED tube lamp according to the first voltage level comprises:
comparing the first voltage level with the second voltage level;
generating the indication with a first logic level for indicating the foreign external impedance is electrically connected to the LED tube lamp when the first voltage level is greater than the second voltage level; and
generating the indication with a second logic level for indicating the foreign external impedance is not electrically connected to the LED tube lamp when the first voltage level is not greater than the second voltage level.
10. An LED tube lamp, comprising:
a lamp tube;
two end caps, connected to respective ends of the lamp tube;
an LED light strip, mounted on an inner surface of the lamp tube;
a plurality of LED chips, disposed on the LED light strip; and
a power supply module, electrically connected to the LED chips via the LED light strip, and configured to drive the LED chips to emit light, wherein the power supply module comprises:
a detection path circuit, configured to establish a detection path which is capable of affecting an electrical signal on a power line of the power supply module when the detection path is turned on; and
a driving circuit, electrically connected to the detection path circuit, and configured to produce a driving current based on an external driving signal,
wherein when the driving circuit is activated by receiving the external driving signal, the driving circuit enters into a first mode to detect whether a foreign external impedance is electrically connected to the LED tube lamp,
wherein when the foreign external impedance is detected, the driving circuit remains in the first mode, and when the foreign external impedance is not detected, the driving circuit enters into a second mode to produce the driving current, and
wherein the driving circuit is further configured to obtain a dimming message from the electrical signal and adjust the magnitude of the driving current according to the dimming message when in the second mode.
11. The LED tube lamp according to claim 10 , wherein the driving circuit comprises:
a driving controller, electrically connected to the detection path circuit for receiving the electrical signal; and
a conversion circuit, electrically connected to the driving controller and configured to produce the driving current in response to the control of the driving controller.
12. The LED tube lamp according to claim 10 , further comprising:
a rectifying circuit, having input terminals for receiving the external driving signal and output terminals; and
a filtering circuit, having input terminals electrically connected to the output terminals of the rectifying circuit and output terminals electrically connected to the driving circuit.
13. The LED tube lamp according to claim 12 , wherein the detection path circuit comprises:
a first diode, having an anode electrically connected to one of the input terminals of the rectifying circuit and a cathode;
a second diode, having an anode electrically connected to another one of the input terminals of the rectifying circuit and a cathode electrically connected to the cathode of the first diode; and
a transistor, having a first terminal electrically connected to the cathode of the first and the second diodes, a second terminal electrically connected to a ground terminal, and a control terminal configured to receive a pulse signal in the first mode.
14. The LED tube lamp according to claim 12 , wherein the detection path circuit comprises:
a transistor, having a first terminal electrically connected to one of the output terminals of the rectifying circuit, a second terminal electrically connected to another one of the output terminals of the rectifying circuit, and a control terminal configured to receive a pulse signal in the first mode.
15. The LED tube lamp according to claim 10 , wherein the driving circuit determines whether the foreign external impedance is detected based on the following steps:
sampling the electrical signal at a first point in time to obtain a first voltage level;
issuing, after the first point in time, a pulse signal to temporarily turn on the detection path;
sampling the electrical signal at a second point in time to obtain a second voltage level, wherein the second point in time is within the period of the detection path being turned on;
determining the foreign external impedance is electrically connected to the LED tube lamp when the first voltage level is greater than the second voltage level; and
determining the foreign external impedance is not electrically connected to the LED tube lamp when the first voltage level is not greater than the second voltage level.