Linear solid-state lighting with a pulse amplitude control scheme

Patent metadata

Field	Value
Publication number	US-10139093-B2
Application number	US-201815959066-A
Country	US
Kind code	B2
Filing date	Apr 20, 2018
Priority date	Jun 15, 2012
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A linear light-emitting diode (LED)-based tube (LLT) lamp comprises a pulse amplitude control module, a power sustaining device, an LED driving circuit, and LED arrays. The pulse amplitude control module is configured to generate one or more voltage pulses in each alternate-current (AC) cycle in response to a half-wave direct-current (DC) voltage when the LLT lamp starts to receive power from an input AC line voltage and when the half-wave DC voltage drops to a few tens of volts in each AC cycle. The power sustaining device receives the one or more voltage pulses and builds up a DC voltage depending on pulse amplitudes. When an electric shock occurs, the DC voltage built up is not high enough to operate the LED driving circuit and thus to disable the LED arrays, without electric shock current leaking into an electrical conductor of the LLT lamp during relamping or maintenance.

First claim

What is claimed is:

1. A linear light-emitting diode (LED) tube lamp, comprising:
a housing having two ends;
one or more LED arrays disposed between the two ends of the housing;
two lamp bases respectively connected to the two ends of the housing, each lamp base comprising at least one electrical conductor configured to insert into a respective lamp fixture socket;
a direct-current (DC) voltage module comprising at least one full-wave rectifier connected to an input alternate-current (AC) line voltage via the at least one electrical conductor in each lamp base, the DC voltage module configured to convert the input AC line voltage to a full-wave DC voltage and a half-wave DC voltage;
an LED driving circuit comprising a power factor correction (PFC) and control device, a power sustaining device, an electronic switch controlled by the PFC and control device, and a voltage feedback module, the LED driving circuit configured to receive the full-wave DC voltage, to generate an LED voltage and current, and to power up the one or more LED arrays; and
a pulse amplitude control module comprising an input connected to the at least one electrical conductor of each lamp base in a way that the half-wave DC voltage appears at the input, the pulse amplitude control module configured to generate one or more voltage pulses when the half-wave DC voltage drops to a few tens of volts in each AC cycle and to control a DC voltage in the power sustaining device,
wherein:
when an electric shock occurs, the pulse amplitude control module generates the one or more voltage pulses with a relatively low amplitude such that the DC voltage in the power sustaining device fails to reach an operating voltage of the PFC and control device, thereby disabling the PFC and control device and the LED driving circuit without an electric shock current leaking into the at least one electrical conductor of at least one of the two lamp bases that is exposed to the electric shock; and
when the at least one electrical conductor of each lamp base is inserted into the respective lamp fixture socket and receives the input AC line voltage, the pulse amplitude control module generates the one or more voltage pulses with a relatively high amplitude such that the DC voltage in the power sustaining device reaches the operating voltage of the PFC and control device, thereby enabling the LED driving circuit to deliver electrical power to the one or more LED arrays.

2. The linear LED tube lamp of claim 1 , wherein the LED driving circuit further comprises a transformer comprising a primary winding and an auxiliary winding, and wherein the auxiliary winding is connected to the voltage feedback module from which a feedback voltage can be extracted.

3. The linear LED tube lamp of claim 2 , wherein the LED driving circuit further comprises an input filter, a high voltage input configured to receive a filtered DC voltage from the input filter, a current sensing resistor, a flyback diode, and an output capacitor connected to the primary winding of the transformer to build up an output voltage and to power the one or more LED arrays, wherein the primary winding of the transformer is charged and discharged through the electronic switch and the flyback diode, and wherein, responsive to detecting zero current in the primary winding of the transformer within an AC cycle of the input AC line voltage, the PFC and control device generates a zero current detection signal to turn the electronic switch on and off.

4. The linear LED tube lamp of claim 2 , wherein the electronic switch comprises a built-in MOSFET integrated in the PFC and control device, wherein the LED driving circuit further comprises an input filter, a high voltage input configured to receive a filtered DC voltage from the input filter, a current sensing resistor, a flyback diode, and an output capacitor connected to the primary winding of the transformer to build up an output voltage and to power the one or more LED arrays, wherein the primary winding of the transformer is charged and discharged through the built-in MOSFET and the flyback diode, and wherein, responsive to detecting zero current inthe primary winding of the transformer within an AC cycle of the input AC line voltage, the PFC and control device generates a zero current detection signal to turn the built-in MOSFET on and off.

5. The linear LED tube lamp of claim 1 , wherein the LED driving circuit further comprises an autotransformer connected to the voltage feedback module from which a feedback voltage can be extracted.

6. The linear LED tube lamp of claim 1 , wherein the DC voltage module further comprises a rectification diode configured to generate the half-wave DC voltage and to operate the pulse amplitude control module.

7. The linear LED tube lamp of claim 1 , wherein the electronic switch comprises a metal-oxide-semiconductor field-effect transistor (MOSFET), a transistor, or a combination thereof.

8. The linear LED tube lamp of claim 1 , wherein the pulse amplitude module further comprises a resistive load configured to provide a current return path coupled to a common ground of the full-wave rectifier to generate the half-wave DC voltage and to operate the pulse amplitude control module.

9. The linear LED tube lamp of claim 5 , wherein the LED driving circuit further comprises an input filter, a high voltage input configured to receive a filtered DC voltage from the input filter, a current sensing resistor, a flyback diode, and an output capacitor connected to the autotransformer to build up an output voltage and to power the one or more LED arrays, wherein the autotransformer is charged and discharged through the electronic switch and the flyback diode, and wherein, responsive to detecting zero current in the autotransformer within an AC cycle of the input AC line voltage, the PFC and control device generates a zero current detection signal to turn the electronic switch on and off.

10. The linear LED tube lamp of claim 1 , wherein the pulse amplitude control module further comprises a first control mechanism, a second control mechanism, and a third control mechanism, respectively comprising a first switch, a second switch, and a third switch, wherein the first control mechanism is coupled to the voltage feedback module, and wherein when the electric shock does not occur, and when the LED driving circuit is operated, the first control mechanism operates to disable the second control mechanism and the third control mechanism.

11. The linear LED tube lamp of claim 10 , wherein the first switch is configured to pull down a voltage in the second control mechanism to disable the second control mechanism.

12. The linear LED tube lamp of claim 10 , wherein each of the first switch, the second switch, and the third switch comprises an MOSFET, a transistor, or a combination thereof.

13. The linear LED tube lamp of claim 10 , wherein the second control mechanism further comprises one or more voltage-reduced devices, a feed-forward diode, and a Zener diode voltage regulator, the second control mechanism configured to receive the half-wave DC voltage via the one or more voltage-reduced devices and the feed-forward diode to set up a reference voltage and to create initial one or more pulses in each AC cycle in response to the half-wave DC voltage.

14. The linear LED tube lamp of claim 13 , wherein the third switch is coupled to receive the half-wave DC voltage and configured to create the one or more voltage pulses in response to the initial one or more pulses in each AC cycle.

15. The linear LED tube lamp of claim 1 , wherein the pulse amplitude control module further co

Assignees

• Aleddra Inc

Inventors

• Hsia Chungho

Classifications

• H05B45/355

  Power factor correction [PFC]; Reactive power compensation · CPC title

• H05B45/3578

  Emulating the electrical or functional characteristics of discharge lamps · CPC title

• F21V25/04 Primary

  breaking the electric circuit · CPC title

• F21Y2115/10

  Light-emitting diodes [LED] · CPC title

• H02M1/32

  Means for protecting converters other than automatic disconnection · CPC title