LED tube lamp with improved compatibility with an electrical ballast
A light emitting diode (LED) tube lamp includes a lamp tube; a first external connection terminal coupled to the lamp tube and for receiving an external driving signal; a second external connection terminal coupled to the lamp tube and for receiving an external driving signal; a first rectifier coupled to the first external connection terminal and configured to rectify the external driving signal to produce a rectified signal; a second rectifier coupled to the second external connection terminal for rectifying the external driving signal; a filtering circuit coupled to the first rectifier and the second rectifier and configured to filter the rectified signal to produce a filtered signal; an LED lighting module coupled to the filtering circuit and configured to receive the filtered signal for emitting light; and a first bypass circuit coupled between the first rectifying circuit and the second external connection terminal. The first external connection terminal is an input terminal for the first rectifier and a first node is directly electrically connected to an output terminal for the first rectifier. In addition, the second external connection terminal is an input terminal for the second rectifier and a second node is directly electrically connected to an output terminal for the second rectifier. Further the first bypass circuit includes a first terminal connected to second external connection terminal and a second terminal connected to the first node, and the first bypass circuit is configured such that when the external driving signal is initially input between the first external connection terminal and the second external connection terminal, the first bypass circuit initially conducts current bypassing the LED lighting module to prevent the LED tube lamp from emitting light, until the bypass circuit enters an open-circuit state, allowing a current to flow through the LED lighting module and thereby allowing the LED tube lamp to emit light.
1. A light emitting diode (LED) tube lamp, comprising:
a lamp tube;
a first external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a second external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a first rectifying circuit coupled to the first external connection terminal and configured to rectify the external driving signal to produce a rectified signal;
a second rectifying circuit coupled to the second external connection terminal for rectifying the external driving signal;
a filtering circuit coupled to the first rectifying circuit and the second rectifying circuit, and configured to filter the rectified signal to produce a filtered signal;
an LED lighting module coupled to the filtering circuit and configured to receive the filtered signal for emitting light; and
a first ballast interface circuit coupled between the first rectifying circuit and the second external connection terminal,
wherein the first ballast interface circuit is configured such that when the external driving signal is initially input between the first external connection terminal and the second external connection terminal, the first ballast interface circuit initially conducts current bypassing the LED lighting module to prevent the LED tube lamp from emitting light, until the ballast interface circuit enters an open-circuit state, allowing a current input at the first external connection terminal and second external connection terminal to flow through the LED lighting module and thereby allowing the LED tube lamp to emit light.
2. The LED tube lamp of claim 1 , further comprising:
a third external connection terminal coupled to the second rectifying circuit; and
a second ballast interface circuit coupled between the third external connection terminal and the first rectifying circuit.
3. The LED tube lamp of claim 1 , further comprising:
a node at which a first terminal of the first ballast interface circuit, a first terminal of the second ballast interface circuit, a terminal of the first rectifying circuit, and a terminal of the filtering circuit connect to each other.
4. The LED tube lamp of claim 1 , wherein:
the first ballast interface circuit is coupled between the first rectifying circuit and the second rectifying circuit.
5. The LED tube lamp of claim 1 , wherein:
the first ballast interface circuit includes at least one electronic switch.
6. The LED tube lamp of claim 5 , wherein:
the first ballast interface circuit is configured so that:
when the external driving signal is initially input between the first external connection terminal and the second external connection terminal, the first ballast interface circuit initially conducts current by the at least one switch conducting.
7. The LED tube lamp of claim 6 , further comprising:
an RC circuit included in the first ballast interface circuit, wherein:
the RC circuit causes the electronic switch to be in an open state to cut off current after a period of time of the initial conduction of current by the at least one switch.
8. The LED tube lamp of claim 5 , wherein the at least one electronic switch is coupled between the first rectifying circuit and the second external connection terminal.
9. The LED tube lamp of claim 8 , wherein the at least one electronic switch includes a first switch connected between a first resistor, a first capacitor, and a first diode.
10. The LED tube lamp of claim 9 , wherein the at least on electronic switch includes a second switch connected in parallel with the first switch.
11. The LED tube lamp of claim 1 , wherein:
the second rectifying circuit includes:
a rectifier coupled to a terminal adapter circuit.
12. The LED tube lamp of claim 11 , wherein:
the rectifier is coupled between the second external connection terminal and the terminal adapter circuit; and
the terminal adapter circuit is coupled between a first node of the rectifier and the first rectifying circuit.
13. The LED tube lamp of claim 12 , wherein:
the first ballast interface circuit, terminal adapter circuit, and rectifier connect to each other at the first node.
14. The LED tube lamp of claim 11 , wherein:
the terminal adapter circuit is coupled between the second external connection terminal and the rectifier; and
the rectifier is coupled between the terminal adapter circuit and the first rectifying circuit.
15. The LED tube lamp of claim 14 , further comprising:
a third external connection terminal coupled to the terminal adapter circuit;
wherein the terminal adapter circuit comprises a filament-simulating circuit including a resistor and a capacitor connected in parallel between the second external connection terminal and the third external connection terminal.
16. The LED tube lamp of claim 14 , further comprising:
a third external connection terminal coupled to the terminal adapter circuit;
wherein the terminal adapter circuit comprises a filament-simulating circuit including at least one negative temperature coefficient resistor.
17. The LED tube lamp of claim 1 , further comprising:
a third external connection terminal [ 504 ] coupled to the second rectifying circuit; and
a filament-simulating circuit coupled between the second external connection terminal and the third external connection terminal.
18. The LED tube lamp of claim 17 , wherein:
the filament-simulating circuit includes a resistor and capacitor connected in parallel between the first node and one of the second external connection terminal or the third external connection terminal.
19. The LED tube lamp of claim 17 , wherein:
the second rectifying circuit includes the filament-simulating circuit and a rectifier.
20. The LED tube lamp of claim 17 , wherein:
the filament-simulating circuit simulates the operation of filaments of a fluorescent tube lamp, so that a current flowing through the filament-simulating circuit when an external lamp driving circuit performs filament detection is below about 1 [A].
21. The LED tube lamp of claim 1 , wherein the LED lighting module includes:
a flexible circuit sheet on which a plurality of light emitting diodes (LEDs) are disposed,
wherein the plurality of light emitting diodes are connected to emit light based on the filtered signal.
22. The LED tube lamp of claim 21 , wherein the flexible circuit sheet extends along a length of the lamp tube and includes end portions at opposite ends of the lamp tube on which LEDs are not disposed and which bends away from the lamp tube.
23. The LED tube lamp of claim 22 , wherein the end portions are an integral portion of the flexible circuit sheet.
24. The LED tube lamp of claim 22 , wherein the flexible circuit sheet passes through a transition region in the lamp tube where the lamp tube narrows.
25. A light emitting diode (LED) tube lamp, comprising:
a lamp tube;
a first external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a second external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a first rectifier coupled to the first external connection terminal and configured to rectify the external driving signal to produce a rectified signal;
a second rectifier coupled to the second external connection terminal for rectifying the external driving signal;
a filtering circuit coupled to the first rectifier and the second rectifier and configured to filter the rectified signal to produce a filtered signal;
an LED lighting module coupled to the filtering circuit and configured to receive the filtered signal for emitting light; and
a first bypass circuit coupled between the first rectifying circuit and the second external connection terminal,
wherein the first external connection terminal is an input terminal for the first rectifier and a first node is directly electrically connected to an output terminal for the first rectifier;
wherein the second external connection terminal is an input terminal for the second rectifier and a second node is directly electrically connected to an output terminal for the second rectifier,
wherein the first bypass circuit includes a first terminal connected to second external connection terminal and a second terminal connected to the first node, and
wherein the first bypass circuit is configured such that when the external driving signal is initially input between the first external connection terminal and the second external connection terminal, the first bypass circuit initially conducts current bypassing the LED lighting module to prevent the LED tube lamp from emitting light, until the bypass circuit enters an open-circuit state, allowing a current to flow through the LED lighting module and thereby allowing the LED tube lamp to emit light.
26. The LED tube lamp of claim 25 , wherein:
the first bypass circuit includes at least one switch configured to initially pass through a current and to later cut off the current.
27. The LED tube lamp of claim 25 , wherein:
the first node is also directly electrically connected to an input terminal of the filtering circuit.
28. A light emitting diode (LED) tube lamp, comprising:
a lamp tube;
a first external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a second external connection terminal coupled to the lamp tube and for receiving an external driving signal;
a first rectifier coupled to the first external connection terminal and configured to rectify the external driving signal to produce a rectified signal, wherein the first external connection terminal is an input terminal for the first rectifier and a first node is directly connected to an output terminal for the first rectifier;
a second rectifier coupled to the second external connection terminal and configured to rectify the external driving signal, wherein the second external connection terminal is an input terminal for the second rectifier and a second node is directly connected to an output terminal for the second rectifier;
a filtering circuit coupled to the first rectifier and the second rectifier and configured to filter the rectified signal to produce a filtered signal;
an LED lighting module coupled to the filtering circuit and configured to receive the filtered signal for emitting light; and
means for initially, during a first time period, causing a current to pass from the second external connection terminal to the first node by bypassing the LED lighting module and to later, during a second time period following the first time period, causing a current to pass from the second external connection terminal to the first node by passing through the LED lighting module, thereby causing the LED tube lamp to emit light.
29. The LED tube lamp of claim 28 , wherein the means include at least one switch configured to be in a closed, conducting state during the first time period and to be in an open, cutoff state during the second time period.
30. The LED tube lamp of claim 28 , wherein:
the first node is also directly connected to an input terminal of the filtering circuit.