LED tube lamp
A ballast-bypass light-emitting diode (LED) tube lamp includes at least a first and second external connection terminal, the first and second external connection terminals respectively connected to opposite sides of the ballast by-pass LED tube lamp. The tube lamp includes an LED module, configured to emit light in response to a driving current, and a power supply module, electrically connected to the first and second external connection terminals for receiving an AC driving signal and configured to provide the driving current to the LED module. The power supply module comprises a rectifying circuit, a filtering circuit, a driving circuit, and a circuit electrically connected to the driving circuit and configured to operate in response to whether a foreign external impedance is connected to the LED tube lamp. When part of the LED tube lamp is electrically connected to an external power source and the foreign external impedance is electrically connected to the LED tube lamp, the first circuit disables the driving circuit so as to limit the generation of the driving current to prevent the LED module from emitting light based on the driving current. When both ends of the LED tube lamp are electrically connected to an external power source and the foreign external impedance is not electrically connected to the LED tube lamp, the first circuit enables the driving circuit so as to not limit the generation of the driving current in order to allow the LED module to emitting light based on the driving current.
1. A ballast-bypass light-emitting diode (LED) tube lamp having at least a first and second external connection terminal, the first and second external connection terminals respectively connected to opposite sides of the ballast by-pass LED tube lamp, comprising:
an LED module, configured to emit light in response to a driving current; and
a power supply module, electrically connected to the first and second external connection terminals for receiving an AC driving signal and configured to provide the driving current to the LED module,
wherein the power supply module comprises:
a rectifying circuit, configured to receive the AC driving signal from a first rectifying input terminal and a second rectifying input terminal;
a filtering circuit, electrically connected to the rectifying circuit via a first rectifying output terminal and a second rectifying output terminal;
a driving circuit, electrically connected to the filtering circuit and the LED module, and configured to generate the driving current; and
a first circuit, electrically connected to the driving circuit and configured to operate in response to whether a foreign external impedance is connected to the LED tube lamp, wherein:
when part of the LED tube lamp is electrically connected to an external power source and the foreign external impedance is electrically connected to the LED tube lamp, the first circuit disables the driving circuit so as to limit the generation of the driving current to prevent the LED module from emitting light based on the driving current, and
when both ends of the LED tube lamp are electrically connected to an external power source and the foreign external impedance is not electrically connected to the LED tube lamp, the first circuit enables the driving circuit so as to not limit the generation of the driving current in order to allow the LED module to emitting light based on the driving current.
2. The ballast-bypass LED tube lamp according to claim 1 , wherein the driving circuit comprises a controller having a power input terminal and configured to control the generation of the driving current, and the first circuit comprises:
a detection pulse generating circuit, configured to generate a pulse signal;
a detection path circuit, electrically connected to the detection pulse generating circuit for receiving the pulse signal and configured to form a detection path which is a branch circuit extending from a power loop of the power supply module;
a detection determining circuit, electrically connected to the detection path circuit and configured to detect a signal on the detection path and generate an adjustment control signal; and
a control circuit, electrically connected to the detection determining circuit and the power input terminal, and configured to affect a signal on the power input terminal in response to the adjustment control signal.
3. The ballast-bypass LED tube lamp according to claim 2 , wherein the detection path circuit comprises:
a resistor; and
a transistor, electrically connected to the resistor in series to form the detection path, and configured to turn on or cut off in response to the pulse signal.
4. The ballast-bypass LED tube lamp according to claim 3 , wherein the detection path circuit further comprises:
a first diode, having an anode electrically connected to the first rectifying input terminal and a cathode electrically connected to the resistor via a first detection connection terminal; and
a second diode, having an anode electrically connected to the second rectifying input terminal and a cathode electrically connected to the resistor via a first detection connection terminal.
5. The ballast-bypass LED tube lamp according to claim 2 , wherein the detection determining circuit comprises:
a sampling circuit, configured to sample the signal on the detection path according to a set time point and generate a plurality of sample signals, respectively corresponding to the signal on the detection path, at different time points.
6. The ballast-bypass LED tube lamp according to claim 5 , wherein the detection determining circuit further comprises:
a comparison circuit, electrically connected to the sampling circuit and configured to receive the sample signals and compare at least two sample signals with each other and generate a comparison result; and
a determining circuit, electrically connected to the comparison circuit and configured to generate the adjustment control signal according to the comparison result.
7. The ballast-bypass LED tube lamp according to claim 2 , wherein the control circuit comprises:
a bias adjustment circuit, configured to electrically connect the power input terminal to a ground terminal to pull a voltage on the power input terminal to a level of the ground terminal when receiving the adjustment control signal indicating the foreign external impedance is electrically connected to the LED tube lamp, and to electrically disconnect the power input terminal from the ground terminal when receiving the adjustment control signal indicating that the foreign external impedance is not electrically connected to the LED tube lamp.
8. The ballast-bypass LED tube lamp according to claim 1 , further comprising:
a detection pulse generating circuit, configured to generate a pulse signal; and
a detection path circuit, electrically connected to the detection pulse generating circuit for receiving the pulse signal and configured to form a detection path,
wherein the detection path circuit is electrically connected to the first rectifying output terminal via a first detection connection terminal, and electrically connected to the second rectifying output terminal via a second detection connection terminal.
9. The ballast-bypass LED tube lamp according to claim 8 , wherein the detection path circuit further comprises:
a current limiting element, electrically connected between the first rectifying output terminal and the filtering circuit, and configured to limit direction of current on a power loop of the power supply module.
10. The ballast-bypass LED tube lamp according to claim 9 , wherein the current limiting element comprises:
a diode, having an anode electrically connected to the first rectifying output terminal and to a resistor or a transistor via the first detection connection terminal and a cathode electrically connected to the filtering circuit.