LED tube lamp
A light-emitting diode (LED) tube lamp comprising a tube, end caps with contact pins and located on both ends of the tube, a first rectifying circuit and a second rectifying circuit and a filtering circuit that are coupled with the contact pins on the two end caps respectively, and a switch circuitry that is located between the rectifying circuits and the filtering circuit characterized in that the switch circuitry is capable of detecting whether the LED tube lamp is correctly installed on a lamp socket so as to reduce the risk of electric shock.
1. A light-emitting diode (LED) tube lamp comprising a tube, end caps with contact pins and located on both ends of the tube, a first rectifying circuit and a second rectifying circuit and a filtering circuit that are coupled with the contact pins on the two end caps respectively, and a switch circuitry that is located between the rectifying circuits and the filtering circuit characterized in that the switch circuitry comprises:
a first terminal that is coupled with either one or both of the contact pins,
a second terminal that is coupled to a ground terminal, and
a third terminal that is coupled with the filtering circuit;
wherein the switch circuitry further comprises a rectifying module, a reference voltage generating unit, a signal capturing unit, a signal processing unit and a transistor;
a source electrode and a drain electrode of the transistor are connected with the second terminal and the third terminal of the switch circuitry, respectively;
at least one of the first and the second rectifying circuits served as the rectifying module of the switch circuitry to receive an external driving signal via the first terminal and to output a driving voltage to the reference voltage generating unit;
the signal capturing unit is used to sample an electric signal passing through the second terminal and the third terminal of the switch circuitry; the signal capturing unit is further used to compare the sampled electric signal and a reference signal outputted by the reference voltage generating unit and output a detection result signal; the signal processing unit receives the detection result signal and comprises a driver to output a control signal with high-low level to a gate electrode of the transistor,
wherein when the contact pin on either end of the LED tube lamp is connected to the external driving signal, if the electric signal sampled by the signal capturing unit is lower than a set value, the switch circuitry will be disconnected; if the electric signal sampled by the signal capturing unit equal to or higher than the set value, the switch circuitry will be connected.
2. The LED tube lamp according to claim 1 , wherein the reference voltage generating unit, the signal capturing unit, the signal processing unit and the transistor of the switch circuitry forms a three-terminal switch device having a power terminal, a first switching terminal and a second switching terminal.
3. The LED tube lamp according to claim 2 , wherein the power terminal is connected to the output of the rectifying module for receiving the driving voltage, the first switching terminal is connected to a rectifying output terminal via the second terminal, and the second switching terminal is connected to the filtering circuit via the third terminal.
4. The LED tube lamp according to claim 1 , wherein the set value is 1.25V.
5. The LED tube lamp according to claim 1 , wherein the signal capturing unit comprises:
an OR gate, having a first input end, a second input end, and an output end connected to the signal processing unit;
a first comparator, having a first input end connected to one end of the transistor, a second input end receiving a first reference signal, and an output end connected to the first input end of the OR gate; and
a second comparator, having a first input end connected to a second reference signal, a second input end connected to the first input end of the first comparator, and an output end connected to the second input end of the OR gate.
6. The LED tube lamp according to claim 1 , wherein the at least one of the first and the second rectifying circuit is a full-wave bridge rectifying circuit.
7. The LED tube lamp according to claim 1 , wherein the at least one of the first and the second rectifying circuit is a half-wave bridge rectifying circuit.
8. The LED tube lamp according to claim 1 , wherein the level of the electric signal sampled by the signal capturing unit is related to an additional impedance connected to the LED tube lamp.
9. The LED tube lamp according to claim 1 , wherein when the electric signal corresponding to an additional 500 ohm, which is used to emulate the conductive resistance of human body in transient response, is detected by the signal capturing unit, the electric signal sampled by the signal capturing unit is lower than the set value.
10. The LED tube lamp according to claim 2 , wherein the three-terminal switch device further comprises a signal generating unit configured to generate a pulse signal.
11. The LED tube lamp according to claim 10 , wherein the signal processing unit further comprises:
an OR gate, having a first input end connected to the signal generating unit, a second input end, and an output end connected to an input end of the driver; and
a latch circuit, having a first input end for receiving a driving voltage, a second input end connected to the signal capturing unit, and an output connected to the second input end of the OR gate.
12. The LED tube lamp according to claim 11 , wherein the latch circuit comprises a D flip-flop, the first input end of the latch circuit is a data input end of the D flip-flop, and the second input end of the latch circuit is a clock input end of the D flip-flop.
13. The LED tube lamp according to claim 10 , wherein if the electric signal sampled by the signal capturing unit is lower than the set value, the signal processing unit outputs the pulse signal to the transistor and causes the switch circuitry will only be connected during a pulse-on time of the pulse signal.
14. The LED tube lamp according to claim 13 , wherein the pulse-on time of each pulse is between 10 microseconds to 1 millisecond.
15. A LED straight tube lamp comprising a tube, lamp caps with contact pins and located on both ends of the tube, a first rectifying unit and a second rectifying unit and a filter unit that are coupled with the pins on the two end caps respectively, and a switch unit that is located between the rectifying units and the filter unit characterized in that the switch unit comprises:
a sampling end that is coupled with either one or both of the contact pins,
a first end that is earthed, and
a second end that is coupled with the filter unit;
wherein the switch unit further comprises a rectifying module, a reference module, an impedance detecting module, a control module, a driver module and a transistor;
a source electrode and a drain electrode of the transistor are connected with the first end and second end of the switch unit, respectively;
the sampling end outputs sampling signal to the rectifying module, which outputs rectified sampling signal to the reference module;
the impedance detecting module is used to detect the current on the switch unit's first end; the control module is used to compare the current detected by the impedance detecting module and the current outputted by the reference module and output control signal to the driver module; the driver module outputs high-low level signal to the gate of the transistor, and
wherein when the contact pin on either end of the LED straight tube lamp is connected to a power supply, if the current detected by the impedance detecting module is lower than a set value, the switch unit will be disconnected; if current detected by the impedance detecting module equal to or higher than the set value, the switch unit will be connected.
16. The LED straight tube lamp described in claim 15 , wherein the rectifying module described is a semi-wave rectifying module.
17. The LED straight tube lamp described in claim 15 , wherein an impedance detected by the impedance detecting module is 500˜1500 Ohm.
18. The LED straight tube lamp according to claim 17 , wherein an impedance detected by the impedance detecting module is 500 Ohm configured to emulate the conductive resistance of human body in transient response.
19. The LED straight tube lamp according to claim 15 , wherein the rectifying module comprises one of the first rectifying unit and the second rectifying unit.