Patent Application
20150223302
The present invention relates generally to lighting systems, and more particularly to methods and systems for controlling lighting color.
Light Emitting Diodes (LED)s have become a prevailing technology in the industry of lighting. A common technique known in the art to control LED lighting color comprises using three LEDs of different basic colors, typically red, green and blue. An LED driver then changes the proportion of the lighting intensities between the individual LEDs, typically in response to a remote command, so as to adjust the overall lighting color to a desired one.
A common version of the above technique comprises an LED pair assembly, typically one yellow-white colored LED and the one noon-daylight colored LED. Upon changing the relative intensities in this case, the overall lighting temperature of the assembly can be adjusted between about 3000 Kelvin-deg of the yellow-white LED to about 5500 Kelvin-deg of the noon-daylight LED. However, a minimum of three wires are needed in the above examples between the LED driver and the LED pair assembly, which complicates wiring installation, especially when an existing wiring installation has to be reused.
Thus, it would be desirable to achieve a variable color/temperature lighting solution that resorts to only two wires connecting the lighting driver and the LED pair assembly.
Accordingly, it is a principal object of the present invention to provide improved methods and systems of variable color/temperature lighting comprising two wire connection between the lighting driver and lighting source assembly. Thus, in accordance with an embodiment of the present invention, a method of controlling lighting color is disclosed, wherein a lighting assembly is provided comprising first and second lighting sources of different colors interconnected in opposite polarity directions. The lighting color control method comprises the steps of applying a bipolar driving signal to the lighting assembly, thereby alternately driving the first and second lighting sources, and determining an appropriate polarity ratio of the bipolar driving signal for achieving a desired lighting color, in particular lighting temperature, of the lighting assembly.
In an embodiment, the method further comprises the step of applying an activity duty cycle to the bipolar driving signal, for dimming the emitted light. This dimming is optionally determined according a dimming angle detected on an AC power line from which the bipolar driving signal is derived. In some embodiments, the detected dimming angle also affects the temperature of the lighting emitted by the lighting assembly.
In an embodiment, the method further comprises the step of remotely controlling the bipolar driving signal polarity ratio.
In some embodiments, each of the first and second lighting sources comprises one or more light emitting diode (LED) chains, wherein the chains within each of the lighting sources are connected in parallel and each chain comprises at least one LED.
In an embodiment, each of the first and second lighting sources comprises a reverse voltage protection means.
In an embodiment, the first lighting source is adapted to emit a yellow-white color and the second lighting source is adapted to emit a noon-daylight color.
In accordance with an embodiment of the present invention, there is also provided a lighting driver comprising a driving unit configured to drive a lighting assembly with a bipolar driving signal, and a control unit coupled to the driving unit and configured to set a polarity ratio of the bipolar driving signal for determining the color of lighting emitted by the lighting assembly.
In accordance with an embodiment of the present invention, there is also provided a lighting system comprising a lighting driver configured to produce a bipolar driving signal, and a lighting assembly comprising first and second lighting sources of different colors interconnected in opposite polarity directions and adapted to be alternately driven by the bipolar driving signal for affecting the color of lighting emitted by the lighting assembly corresponding to the bipolar driving signal polarity ratio.
The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which:
Embodiments of the present invention provide lighting systems in which lighting color and temperature of an LED assembly can be adjusted without resorting to more than two wires for connecting the LED assembly to an LED driver. This is achieved due to bipolar driving signal drive of an LED pair interconnected within the LED assembly in opposite polarity directions, as detailed hereinafter.
Referring to
LED assembly 109 comprises first and second lighting sources 110 and 111 interconnected in opposite polarity directions, i.e. back-to-back. In this way, voltage V drives lighting sources 110 and 111 alternately. In embodiments of the present invention each lighting source comprises one or more LED chains connected in parallel, each comprising one or more LEDs. Only one LED chain per lighting source is depicted in
In
Diodes 112 and 113 protect LED chains 110 and 111 respectively from reverse voltage breakdown. Resistor 114 determines the current flowing through LED chains 110 and 111 when driving unit 116 functions as an AC voltage source having a peak voltage Vp. In another embodiment, driving unit 116 functions as an AC current source having a peak current Ip, which obviates the need for resistor 114. In some embodiments, any applicable serial and parallel connectivity of multiple LED assemblies such as assembly 109 may be used.
A control unit 120, typically Pulse Width Modulation (PWM) based, controls driving unit 116. In an embodiment, control unit 120 may affect various operating parameters of lighting system 100 such as lighting color/temperature and lighting intensity/dimness, as described below. In an embodiment, control unit 120 also constantly senses whether the AC power received from AC power line 108 is affected by a phase cut dimmer, and detects the dimming angle in this case. This is depicted in
LED driver 104 also comprises a wireless adapter 128, thereby allowing remote control of driving unit 116 through wireless connectivity 138. In embodiments of the present invention, wireless adapter 128 may support various types of communication protocols such as Bluetooth, ZigBee and Wi-Fi.
In an embodiment, control unit 120 comprises a micro-processor which executes a program code that can manage wireless adapter 128, as well as interpret command and monitoring messages received from a remote location through wireless adapter 128. In an alternative embodiment, control unit 120 comprises a simple electronic circuit and needs wireless adapter 128 to convert between remote messages, at the wireless side of wireless adapter 128, and variable electrical levels at its controller side. In some alternative embodiments, control unit 120 is combined with LED driver 116. In an embodiment, when the lighting intensity of LED driver 104 is remotely controlled while it is fed through a phase cut dimmer, control unit 120 would prioritize the remotely commanded lighting intensity, provided that it is not too high relative to the lighting intensity implied from the dimming angle.
In embodiments of the present invention, various remote control means may communicate with LED driver 104 through wireless adapter 128. Some of those remote control means are shown in
In another embodiment, wherein the AC power received from AC power line 108 is affected by a phase cut dimmer, control unit 120 adjusts the lighting temperature as well as the lighting intensity of LED assembly 109. This is done through driving unit 116, in accordance with the detected dimming angle. This is typically done based on an angle-to-temperature mapping table included in control unit 120. This mapping typically causes decrease of the lighting temperature, from maximum to minimum, respectively to the diming angle decrease from maximum to minimum. In an alternative embodiment, the lighting temperature increases from minimum to maximum, respectively to the diming angle decrease from maximum to minimum. The exact mechanism of lighting temperature control is described below.
The above description has focused on the specific elements of lighting system 100 that are essential for understanding certain features of the disclosed techniques. Conventional elements the system not needed for this understanding have been omitted from
Flowchart 300 is an example flowchart, which was chosen purely for the sake of conceptual clarity. In alternative embodiments, any other suitable flowchart can also be used for illustrating the disclosed method. Method steps that are not mandatory for understanding the disclosed techniques were omitted from
Although the embodiments described herein mainly address LED based lighting systems, the methods and systems exemplified by these embodiments can also be applied to other suitable lighting sources, as well as to other applications that may be suitably affected by variable polarity ratio of a bipolar driving signal drive.
It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.
riving signal.
| Number | Date | Country | |
|---|---|---|---|
| 61935874 | Feb 2014 | US |
