LED based lighting application

Patent metadata

Field	Value
Publication number	US-9750093-B2
Application number	US-201614995469-A
Country	US
Kind code	B2
Filing date	Jan 14, 2016
Priority date	Sep 5, 2008
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A lighting application is provided that includes an LED assembly including a serial connection of two or more LED units, each LED unit including one or more LEDs, each LED unit being provided with a controllable switch for substantially short-circuiting the LED unit. The lighting application further includes a control unit for controlling a drive unit and arranged to receive a signal representing a voltage level of the supply voltage, and control the switches in accordance with the signal. An LED driver is provided that enables to operate a TRIAC based dimmer at an optimal holding current and an LED driver including a capacitor as a switchable buffer.

First claim

The invention claimed is:

1. A lighting application comprising:
an LED assembly comprising two or more LED units, each LED unit comprising one or more LEDs, the LED assembly further comprising a switch assembly comprising one or more controllable switches for modifying a topology of the LED assembly from a series connection of two of the LED units to a parallel connection of the two of the LED units, the LED assembly, in use, being powered from a supply voltage, and
a control unit comprising an input terminal arranged to receive a signal representing a voltage level of the supply voltage or a load current of the LED assembly,
output terminal for providing a control signal to the switch assembly to control the switch assembly in accordance with the signal, thereby modifying the topology of the LED assembly from the series connection of two of the LED units to the parallel connection of the two of the LED units when the signal representing the voltage level of the supply voltage indicates that the voltage level of the supply voltage is reduced, and
a waveform analyzer arranged to assess the supply voltage and provide the signal to the control unit.

2. The lighting application according to claim 1 , further comprising a drive unit for powering the LED assembly, the drive unit, in use, being powered from the supply voltage.

3. The lighting application according to claim 2 , wherein the drive unit comprises a linear regulator or a switching regulator for powering the LED assembly.

4. A lighting application according to claim 1 , wherein the LED assembly comprises a serial connection of two or more LED units and wherein the switch assembly comprises two or more controllable switches for substantially short-circuiting the respective two or more LED units.

5. The lighting application according to claim 1 , wherein the control unit is further configured to determine a maximum number of LED units that are powered by the supply voltage based on the signal, and control the switches according to the maximum.

6. The lighting application according to claim 1 , wherein the supply voltage comprises a dimmer circuit output voltage.

7. The lighting application according to claim 1 , wherein the supply voltage comprises a periodic voltage.

8. The lighting application according to claim 7 , wherein the control signal is synchronized with the periodic voltage.

9. The lighting application according to claim 8 , wherein the control unit is arranged to apply a duty cycle modulation of a current provided to the LED assembly by controlling the switch assembly.

10. The lighting application according to claim 9 , wherein a duty cycle period of the duty cycle modulation is selected such that a period of the supply voltage divided by the duty cycle period results in an integer value.

11. The lighting application according to claim 1 , wherein the waveform analyzer is arranged to determine a zero crossing of the supply voltage.

12. A lighting application comprising:
an LED assembly comprising two or more LED units, each LED unit comprising one or more LEDs, the LED assembly further comprising a switch assembly comprising one or more controllable switches for modifying a topology of the LED assembly from a series connection of two of the LED units to a parallel connection of the two of the LED units, the LED assembly, in use, being powered from a supply voltage, and
a control unit comprising an input terminal arranged to receive a signal representing a voltage level of the supply voltage or a load current of the LED assembly,
output terminal for providing a control signal to the switch assembly to control the switch assembly in accordance with the signal, thereby modifying the topology of the LED assembly from the series connection of two of the LED units to the parallel connection of the two of the LED units when the signal representing the voltage level of the supply voltage indicates that the voltage level of the supply voltage is reduced, and
a memory unit for storing waveform information obtained, in use, by a waveform analyzer,
wherein the supply voltage comprises a periodic voltage.

13. A lighting application comprising:
an LED assembly comprising two or more LED units, each LED unit comprising one or more LEDs, the LED assembly further comprising a switch assembly comprising one or more controllable switches for modifying a topology of the LED assembly from a series connection of two of the LED units to a parallel connection of the two of the LED units, the LED assembly, in use, being powered from a supply voltage, and
a control unit comprising an input terminal arranged to receive a signal representing a voltage level of the supply voltage or a load current of the LED assembly,
output terminal for providing a control signal to the switch assembly to control the switch assembly in accordance with the signal, thereby modifying the topology of the LED assembly from the series connection of two of the LED units to the parallel connection of the two of the LED units when the signal representing the voltage level of the supply voltage indicates that the voltage level of the supply voltage is reduced,
wherein the switch assembly further comprises parallel switches connected in parallel to the LED units, wherein the control unit is configured to determine a dimming level from a property of the supply voltage and to drive the switch assembly in accordance with the dimming level.

14. The lighting application according to claim 13 , wherein the property of the supply voltage comprises an average value of the supply voltage, the control unit being configured to determine the dimming level from the average value of the supply voltage.

15. The lighting application according to claim 13 , wherein property of the supply voltage comprises a duty cycle of the supply voltage, the control unit being configured to determine the dimming level from the duty cycle of the supply voltage.

16. A lighting application comprising:
an LED assembly comprising two or more LED units, each LED unit comprising one or more LEDs, the LED assembly further comprising a switch assembly comprising one or more controllable switches for modifying a topology of the LED assembly from a series connection of two of the LED units to a parallel connection of the two of the LED units, the LED assembly, in use, being powered from a supply voltage, and
a control unit comprising an input terminal arranged to receive a signal representing a voltage level of the supply voltage or a load current of the LED assembly,
output terminal for providing a control signal to the switch assembly to control the switch assembly in accordance with the signal, thereby modifying the topology of the LED assembly from the series connection of two of the LED units to the parallel connection of the two of the LED units when the signal representing the voltage level of the supply voltage indicates that the voltage level of the supply voltage is reduced,
wherein the LED assembly comprises serially connected LED units, the switch assembly further comprising parallel switches being connected in parallel to each one of the respective LED units, the control unit being configured to modulate a duty cycle of the LED units in accordance with a set point defining intensity and/or colour output by operating the parallel switches, and wherein the control unit is configured to, when it determines that the voltage level of the supply voltage is too low for powering the LED units simultaneously, drive the parallel switches to activate the LED units sequentially within a pulse width modulation time slot.

Assignees

• Eldolab Holding Bv

Inventors

• Welten Petrus Johannes Maria

Classifications

• H05B45/3575

  by means of dummy loads or bleeder circuits, e.g. for dimmers · CPC title

• H05B45/48 Primary

  having LEDs organised in strings and incorporating parallel shunting devices · CPC title

• H05B45/395

  Linear regulators · CPC title

• H05B45/20

  Controlling the colour of the light · CPC title

• H05B33/083

  Electricity · mapped topic