LED tube lamp with two operating modes compatible with electrical ballasts

Patent metadata

Field	Value
Publication number	US-9756698-B2
Application number	US-201615211813-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Sep 28, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

An LED tube lamp is disclosed. The LED tube lamp includes an LED module for emitting light, the LED module comprising an LED unit comprising an LED; a rectifying circuit for rectifying an external driving signal to produce a rectified signal; and a mode determination circuit configured to detect a state of a property of the rectified signal, for selectively determining on performing a first mode or a second mode of lighting according to the state of the property of the rectified signal; wherein when the LED tube lamp performs the first mode of lighting, the mode determination circuit allows continual current to flow through the LED unit until the external driving signal is disconnected from the LED tube lamp; and when the LED tube lamp performs the second mode of lighting, the mode determination circuit regulates the continuity of current to flow through the LED unit.

First claim

What is claimed is:

1. A light emitting diode (LED) tube lamp configured to receive an external driving signal, comprising:
an LED module for emitting light, the LED module comprising an LED unit comprising an LED;
a rectifying circuit for rectifying the external driving signal to produce a rectified signal;
a filtering circuit connected in parallel with the LED unit;
a discharge device connected in parallel with the LED unit and for discharging when a voltage across the LED unit is larger than a threshold voltage; and
a mode determination circuit configured to detect a state of a property of the rectified signal, for selectively determining on performing a first mode or a second mode of lighting according to the state of the property of the rectified signal;
wherein the mode determination circuit is configured such that when the LED tube lamp performs the first mode of lighting, the mode determination circuit allows continual current to flow through the LED unit until the external driving signal is disconnected from the LED tube lamp; and when the LED tube lamp performs the second mode of lighting, the mode determination circuit regulates the continuity of current to flow through the LED unit.

2. The light emitting diode tube lamp according to claim 1 , wherein the mode determination circuit comprises:
a voltage divider for producing a first fraction voltage of the rectified signal and a second fraction voltage of the rectified signal; and
a control circuit for determining whether the voltage level of the first fraction voltage is in a first voltage range, and whether the voltage level of the second fraction voltage is in a second voltage range;
wherein when the first fraction voltage signal is in the first voltage range, the mode determination circuit determines on performing the first mode of lighting; and when the second fraction voltage is in the second voltage range, the mode determination circuit determines on performing the second mode of lighting.

3. The light emitting diode tube lamp according to claim 2 , wherein the control circuit comprises a switching circuit; when the LED tube lamp performs the first mode of lighting, the mode determination circuit allows continuous current to flow through the LED unit by continuously turning on the switching circuit; and when the LED tube lamp performs the second mode of lighting, the mode determination circuit allows discontinuous current to flow through the LED unit by alternately turning on and off the switching circuit.

4. The light emitting diode tube lamp according to claim 3 , wherein the switching circuit has two terminals respectively coupled to the LED unit and a reference voltage.

5. The light emitting diode tube lamp according to claim 2 , further comprising a switching circuit; when the LED tube lamp performs the first mode of lighting, the mode determination circuit allows continuous current to flow through the LED unit by continuously turning on the switching circuit; and when the LED tube lamp performs the second mode of lighting, the mode determination circuit allows discontinuous current to flow through the LED unit by alternately turning on and off the switching circuit.

6. The light emitting diode tube lamp according to claim 5 , wherein the switching circuit has two terminals respectively coupled to the LED unit and a reference voltage.

7. The light emitting diode tube lamp according to claim 2 , wherein the rectifying circuit has a first output terminal and a second output terminal for outputting the rectified signal, and the voltage divider comprises:
a first voltage divider comprising a first resistor and a second resistor connected to each other between the first and second output terminals of the rectifying circuit, to produce the first fraction voltage; and
a second voltage divider comprising a third resistor and a fourth resistor connected to each other between the first and second output terminals of the rectifying circuit, to produce the second fraction voltage;
wherein the control circuit is coupled to a connection node between the first resistor and the second resistor, for receiving the first fraction voltage; and the control circuit is coupled to a connection node between the third resistor and the fourth resistor, for receiving the second fraction voltage.

8. The light emitting diode tube lamp according to claim 7 , further comprising a switching circuit for the LED tube lamp to perform the second mode of lighting, wherein the second voltage divider further comprises an RC circuit comprising a resistor and a capacitor; one end of the resistor is connected to a connection node between the third resistor and the fourth resistor; another end of the resistor is connected to one end of the capacitor and the control circuit; another end of the capacitor is connected to the second output terminal; and the RC circuit is configured to receive the second fraction voltage and then be charged and discharged repeatedly to alternately turning on and off the switching circuit.

9. The light emitting diode tube lamp according to claim 7 , further comprising a switching circuit for the LED tube lamp to perform the second mode of lighting, wherein the second voltage divider further comprises a pulse width modulation circuit coupled between the switching circuit and a connection node between the third resistor and the fourth resistor, and the pulse width modulation circuit is configured to receive the second fraction voltage and then produce a pulse signal with a duty-cycle responsive to the second fraction voltage, and the pulse signal is used to alternately turning on and off the switching circuit.

10. The light emitting diode tube lamp according to claim 7 , further comprising a switching circuit for the LED tube lamp to perform the second mode of lighting, wherein the control circuit comprises an RC circuit coupled to the switching circuit and a connection node between the third resistor and the fourth resistor, and the RC circuit is configured to receive the second fraction voltage and then be charged and discharged repeatedly to alternately turning on and off the switching circuit.

11. The light emitting diode tube lamp according to claim 7 , further comprising a switching circuit for the LED tube lamp to perform the second mode of lighting, wherein the control circuit comprises a pulse width modulation circuit coupled between the switching circuit and a connection node between the third resistor and the fourth resistor, the pulse width modulation circuit is configured to receive the second fraction voltage and then produce a pulse signal with a duty-cycle responsive to the second fraction voltage, and the pulse signal is used to alternately turning on and off the switching circuit.

12. The light emitting diode tube lamp according to claim 2 , wherein the first voltage range is defined to encompass values less than a first voltage value or larger than a second voltage value which is larger than the first voltage value; and the second voltage range is defined to encompass values larger than a third voltage value and less than a fourth voltage value which is larger than the third voltage value.

13. The light emitting diode tube lamp according to claim 1 , wherein the mode determination circuit comprises a ballast interface circuit as an interface between the LED tube lamp and an electrical ballast used to supply the LED tube lamp.

14. The light emitting diode tube lamp according to claim 1 , wherein the property is the voltage level or the frequency level of the rectified signal.

15. The light emitting diode tube lamp according to claim 1 , wherein the

Assignees

• Jiaxing Super Lighting Electric Appliance Co Ltd

Inventors

• Xiong Aiming
• Liu Xintong
• Wu Xiaojia

Classifications

• F21V3/02 Primary

  characterised by the shape · CPC title

• F21V19/02

  with provision for adjustment, e.g. for focusing · CPC title

• F21V29/83

  the elements having apertures, ducts or channels, e.g. heat radiation holes · CPC title

• F21V15/015

  Devices for covering joints between adjacent lighting devices; End coverings · CPC title

• F21V25/04

  breaking the electric circuit · CPC title