WO2011016720A1

WO2011016720A1 - Led based lighting application

Info

Publication number: WO2011016720A1
Application number: PCT/NL2010/050492
Authority: WO
Inventors: Marc Saes; Petrus Johannes Maria Welten
Original assignee: Eldolab Holding B.V.
Priority date: 2009-08-03
Filing date: 2010-08-03
Publication date: 2011-02-10

Abstract

A method of controlling a lighting application from a user interface device, a lighting application and a user interface device are described. The lighting application e.g. comprises an LED assembly comprising one or more LEDs, a power converter comprising an input terminal for receiving a phase modulated voltage obtained by a phase angle modulation of an AC supply voltage and a control unit. The control unit comprises an input for receiving an input signal representative of the phase modulated voltage, and is arranged to -determine a modulation of the phase angle modulation and -determine a control signal for controlling the LED assembly to provide in an illumination setting based on the modulation and -provide the control signal to the LED assembly via an output of the control unit.

Description

Title

LED based lighting application Technical field

The present invention relates to LED based lighting applications, in particular to LED based applications supplied from an AC dimmer circuit.

Background art.

At present, in architectural and entertainment lighting applications more and more solid state lighting based on Light Emitting Diodes (LED) is used. LED's or LED units have several advantages over incandescent lighting, such as higher power to light conversion efficiency, faster and more precise lighting intensity and colour control. Conventional lighting applications such as filament based lamps or halogen lamps are however still widely applied. In such conventional lighting applications, a user interface, such as a dimmer, is often applied in order to change an intensity or brightness of the lamp or lamps applied. In an example of such a dimmer or dimmer circuit, a phase angle modulation is applied (e.g. by means of Triacs operating as switches) to an AC input voltage (e.g. a 230 V, 50 Hz AC mains voltage) resulting in a dimmer output voltage having a different effective voltage (compared to the AC input voltage). When the dimmer output voltage is provided to the lamp or lamps, a different intensity of the lamp or lamps can be obtained. At present, LED based lighting applications are known that can accept such a dimmer output voltage as a supply voltage and can adjust an intensity of the LED or LEDs of the application according to the received dimmer voltage. By doing so, the dimming of conventional lamps can be mimicked.

In general however, LED based lighting applications allow for changes of other lighting parameters such as colour as well. LED based lighting applications in general comprise an LED assembly comprising one or more LEDs, a power converter (e.g. a switched mode power supply such as a Buck or Boost converter) receiving an input power and converting the input power to a power source suitable for powering the LED assembly, and a controller or control unit for controlling the LED assembly and/or the power converter. As an example, the control unit can control the intensity of the LEDs of the LED assembly by changing a duty cycle of the current provided to the LEDs. In case LEDs of different colour are applied in the LED assembly, the colour output of the LED assembly can be adjusted as well by changing the duty cycle. In present LED based lighting applications that are supplied from a dimmer output voltage however, an adjustment of the colour is either not available or is pre-programmed (e.g. by changing a colour temperature relative to the intensity). As such, the present LED based lighting applications may not, in case they are supplied from a dimmer output voltage, exploit the full potential of the LED assembly of the lighting application. In order to control further illumination parameters (e.g. colour), separate communication tools such as e.g. RF communication should be required which may render both the lighting application and dimmer more complex.

In view of this, it is an object of the present invention to facilitate control of an LED based lighting application when supplied from an AC dimmer voltage.

Summary of the invention

1. According to an aspect of the invention, there is provided a method of controlling a lighting application from a user interface device, the lighting application comprising an LED assembly, a power converter and a control unit for controlling the LED assembly and/or the power converter, the method comprising the steps of

providing, by the user interface device, a phase angle adjustment to a supply voltage, wherein the phase angle adjustment comprises a modulation based on a received input signal representing a desired illumination parameter, thereby obtaining a modulated phase angle adjusted voltage;

providing the modulated phase angle adjusted voltage to the lighting application; determining, by the control unit, the modulation from the modulated phase angle adjusted voltage and determining a control signal from the modulation; controlling the LED assembly and/or power converter by the control signal.

The method of controlling a lighting application according to the invention includes various steps performed by a user interface device (e.g. an AC dimmer) and by a lighting application including an LED assembly, a power converter and a control unit. In accordance with the present invention, an LED assembly comprises one or more LEDs or LED units, an LED unit comprising one or more LEDs. The LEDs or LED units of the LED assembly can be statically or dynamically arranged in series or parallel or any combination thereof. In order to control the light output of the LEDs or LED units, the LED assembly can be provided with one or more electronic switches such as FETs or MOSFETs in order to control a current through the LEDs or LED units. The method according to the invention can be implemented by a user interface device according to the invention and a lighting application according to the invention. According to the method of the invention, a phase angle adjustment is applied to a supply voltage (e.g. an AC supply voltage). Such a phase angle adjustment can e.g. comprise 'cutting-off parts of the supply voltage along a leading edge or a trailing edge of the supply voltage, which can e.g. be realised using a leading edge or trailing edge dimmer. As a result, a phase angle adjusted voltage is obtained (as an example of such a phase angle adjusted voltage, reference can be made to Figure 1 below). Such a phase angle adjustment is applied in conventional AC dimmers to adjust the effective voltage provided to a lighting application (e.g. a light bulb). In order to obtain the phase angle adjustment, firing (i.e. closing) of electronic switches of a dimmer circuit can e.g. be delayed over a certain period (which can be expressed in terms of the phase angle of the supply voltage) relative to a zero-crossing of the supply voltage, thus obtaining a phase angle adjusted voltage.

Most commonly, the AC dimmer employs Triacs to modify the supply voltage, i.e. adjust the phase angle. It should however be emphasised that the other types of dimmers, e.g. based on MOSFET switches or the like may equally be implemented in a user interface device according to the invention or can be applied in the method according to the invention; either trailing or leading edge dimmers can be applied.

In the method according to the invention, the phase angle adjustment comprises a modulation which is based on an input signal received. The resulting voltage is referred to as a modulated phase angle adjusted voltage which is, according to the method of the invention, being provided to the lighting application. The phase angle adjustment as applied can comprise different types of modulations, which are explained in more detail below. In an embodiment, the modulation as applied is such that the average phase angle considered over one or more periods of the supply voltage is substantially unaltered by the application of the modulation. As such, in an example, the modulation can consist of increasing the phase angle adjustment of a first half period of the supply voltage by a certain amount and decreasing the phase angle adjustment of a second half period of the supply voltage by essentially the same amount. Such a symmetrical modulation can e.g. be implemented by a user interface device according to the invention.

In a next step, the control unit of the lighting application receiving the modulated phase angle adjusted voltage (or a signal representing the modulated phase angle adjusted voltage, e.g. a signal proportional to the modulated phase angle adjusted voltage), retrieves or determines the modulation as applied. In an embodiment, a signal representing the modulated phase angle adjusted voltage can be provided to the control unit of the lighting application whereby the control unit can e.g. by means of sampling the signal, determine the modulation. In accordance with the invention, a modulation of the phase angle adjustment should not be confused with a mere change in the applied phase angle, intended to change the effective voltage, as e.g. observed when a known AC dimmer is operated.

According to the method of the invention, the modulation as determined (e.g. by the control unit of the lighting application) is further applied to determine a control signal for controlling the LED assembly to provide the illumination parameter, and the control signal is subsequently provided to the LED assembly or power converter, e.g. via an output of the control unit.

Within the meaning of the present invention, an illumination parameter can e.g. include a colour or brightness set-point. In an embodiment, the information contained in the modulation and representing a colour or brightness set-point is provided in a substantially continuous manner. As such, by applying the appropriate modulation over time, a desired light show can be obtained, i.e. a particular sequence of colour and or intensities can be obtained albeit at a comparatively low bit-rate. Also, an illumination parameter or desired illumination parameter can refer to other properties of a lighting application. As an example, a command to start a certain show (e.g. a sequence of different colour or brightness set-points) can be considered an illumination parameter as well. The input signal representing the illumination parameter may thus directly represent a desired illumination parameter (e.g. in case the input signal is a result of a user operation on a user operable device such as a slider or rotatable knob on a dimmer (in general a user interface device) or may indirectly represent a desired illumination parameter. In the latter case, the information retrieved from the modulation is interpreted by the control unit as a command. As an example, the input signal representing a desired illumination parameter can be an output signal of an ambient sensor. Upon receipt of the information of such a signal (via the modulation applied), a control unit can e.g. adjust an intensity or colour of one or more LEDs of the LED assembly. As such, a desired illumination parameter is obtained in an indirect way, based on the input signal, i.e. based on information provided to the control unit by applying a modulation to the supply voltage. Note that, within the meaning of the present invention, an illumination parameter can also refer to timing aspects. A command to provide a certain illumination during a certain period (e.g. in response to a signal of a motion sensor, said signal e.g provided to the control unit by applying a modulation to the supply voltage) can be considered an illumination parameter as well, within the meaning of the present invention.

In accordance with the invention, the control unit of the lighting application can either control the power converter, the LED assembly or both by providing a control signal based on the modulation. The control signal can e.g. result in the power converter increasing or decreasing the current provided to the LED assembly or, the control signal can e.g. control a duty cycle of one or more LEDs of the LED assembly by controlling an electronic switch of the LED assembly.

By applying the method according to the invention, information or data can be provided to a lighting application by applying a modulated phase angle adjustment (i.e. the phase angle (e.g. firing angle) of the voltage provided is found to vary when a plurality of periods or half periods are observed). The lighting application receiving such a voltage, e.g. at an input terminal of the power converter of the lighting application, can retrieve such information (e.g. by a control unit of the lighting application receiving a signal representative of the voltage) and interpret the information to control the lighting application. The phase angle adjusted voltage (whereby the phase angle adjustment is modulated) as provided to the lighting application is thus applied as a means to communicate information to a lighting application, e.g. in order to set a desired illumination parameter. The communication information (provided via the modulation of the phase angle adjustment) can e.g. be interpreted by the lighting application as an analogue signal (which could be applied directly as a control signal) or as a digital signal.

In an embodiment, the supply voltage as used for obtaining a modulated phase angle adjusted voltage is an AC mains voltage (e.g. 230V, 50 Hz)

In an aspect, the present invention further provides a user interface device enabling a phase angle adjustment to be applied which includes a modulation in order to provide information to a lighting application, the information e.g. being applied for controlling an illumination parameter or set point of the lighting application. As such, the present invention provides a user interface device for converting a supply voltage to a modulated phase angle adjusted voltage, the user interface device comprising:

an electronic circuit for in use, providing a phase angle adjustment to the supply voltage to obtain a phase angle adjusted voltage;

a control unit for controlling the phase angle adjustment as applied by the electronic circuit; the control circuit comprising a terminal for receiving an input signal representative of a desired illumination parameter, the control unit further being arranged to control the electronic circuit to provide a phase angle adjustment comprising a modulation based on the input signal, thereby obtaining a modulated phase angle adjusted voltage and, in use, provide the modulated phase angle adjusted voltage to a lighting application.

In an embodiment, the electronic circuit of the user interface according to the invention comprises a dimmer, e.g. a triac based dimmer. In such a dimmer, an AC supply voltage can be phase angle adjusted by controlling the firing (i.e. closing) of the electronic switches (triacs or the like) of the electronic circuit. The timing of the firing of the electronic switches can e.g. be controlled by the control unit or controller of the user interface device, e.g. in accordance to an input signal received from e.g. a sensor or a user action applied to the user interface device.

The input signal as received can be converted by the controller controlling the firing of the electronic switches into a modulation of the time of firing of the electronic switches. The modulation of the firing instances can e.g. result in a variation of the phase angles applied in consecutive periods or half period of the phase angle adjusted voltage that is outputted by the user interface device (e.g. the triac based dimmer circuit of the user interface) and, in use, provided to a lighting application, in particular, a lighting application according to the invention. In an embodiment, the user interface device according to the invention comprising a user operable device such as a slider or a rotatable knob for providing the input signal in response to a user operation. As such, the user interface device according to the invention can have a similar appearance as a conventional dimmer. It is worth noting that, in accordance with the invention, communication between the user operable device and the control unit receiving the input signal can be implemented in various ways. Communication between the user operable device (or user interface) and the control unit can e.g. be done by PLC or RF or DMX or Ethernet CAN RS232, etc... As such, user operable device can be made to function as a bridge between PLC and the modulated phase angle adjusted voltage, or between RF and the same, or between DMX and the same, Ethernet CAN RS232 etc...

In an embodiment, the dimmer as applied in the electronic circuit can be a leading or trailing edge dimmer. The electronic switches as applied in the dimmer can e.g. be triacs, MOSFETs or the like. The application of a trailing edge or a leading edge dimmer can e.g. be dependent on whether or not an electronic transformer is applied.

According to an aspect of the invention, there is provided a lighting application comprising:

an LED assembly comprising one or more LEDs; a power converter comprising an input terminal for receiving a modulated phase angle adjusted voltage and an output terminal for providing power to the LED assembly;

a control unit for controlling the LED assembly and/or the power converter, wherein the control unit comprises an input for receiving an input signal representative of the modulated phase angle adjusted voltage, and wherein the control unit is arranged to

determine a modulation from the modulated phase angle adjusted voltage;

- determine a control signal for controlling the LED assembly and/or the power converter to provide in an illumination parameter based on the modulation and

provide the control signal to the LED assembly and/or the power converter via an output of the control unit.

By applying a phase angle adjustment comprising a modulation to a supply voltage (i.e. the phase angle (or firing angle) varying when a plurality of periods or half periods are observed), information or data can be provided to a lighting application receiving such a modulated phase angle adjusted voltage. Such information can be retrieved by a control unit of the lighting application and interpreted. As an example, the retrieved modulation can be readily applied as an analogue signal for controlling an illumination parameter of the lighting application. The modulation as retrieved from the modulated phase angle adjusted voltage may also be interpreted as a digital signal e.g. representing a set-point for an illumination parameter of the lighting application. In an embodiment, the modulation as retrieved is interpreted as a digitised form of the required intensity (or required dimming level) of the lighting application, which has been translated to the applied modulated phase angle. By doing so, the required dimming level can be maintained more accurately, as the actual setting of the intensity is determined from the digitised set point rather than determined from the analogue phase angle adjusted supply voltage. Effects of sudden short changes to the phase angle adjusted supply voltage on the illumination provided by the lighting application can be mitigated as the intensity set point as applied will only be altered in case a new set point is received. In order to ensure that a modulation in the phase angle adjustment is not misinterpreted as a new set point (e.g. in a digital format) various protocols can be applied including error detection and correction codes, providing headers or control characters prior to a new set point, etc.... The use of such error codes, headers or control characters may be advised in order to assess the correctness of the information retrieved from the modulation. In case the user interface is operated, it may occur that the phase angle adjusted voltage is altered, thereby rendering is difficult to retrieve the correct information. In such case, when an error in the information obtained from the modulation is detected, it may be preferred to ignore the information and wait for a next message or set point.

The information or data that is provided in the modulation of the phase angle adjusted voltage (e.g. encrypted as a digital signal) can be applied for different purposes.

As an example, it can be applied to set a colour or colour temperature of the LED assembly.

The information or data provided in the modulation of the phase angle adjusted voltage can be considered a command and may thus be used to configure the LED assembly or may e.g. be used to switch the LED assembly from operating in a first mode to operating in a second mode. As an example, in a first mode, the information obtained from the modulation could be interpreted as a colour set-point, whereas, in a second mode, the information can be interpreted as an intensity set-point. As such, comparatively complex adjustments to the illumination parameters of the LED assembly can be realised by the proposed modulation. It can be used to select a subset of LEDs of the LED assembly and subsequently apply an intensity set point (e.g. based on the phase angle applied) only to the selected subset.

Selecting a subset can e.g. be done by providing a group ID to the lighting application via the power signal.

Grouping of LEDs can be realised in different ways:

As an example, the control unit of an LED assembly can be provided with data (e.g. from a central control unit by any means of communication) indicating which LEDs or LED units of the LED assembly belong to a certain group. Such information can also be pre-programmed during manufacturing of the lighting application. More advanced ways of assigning IDs such as group IDs enabling a control unit to address a subset of LEDs or LED units, such methods also known as pairing, can be applied as well.

In an embodiment, the control unit of the lighting application is further arranged to

- determine a reference value of the phase angle adjustment and determine a further control signal for controlling the LED assembly to provide in a further illumination parameter based on the reference value and

provide the further control signal to the LED assembly via the output of the control unit.

Apart from determining a control signal based on the modulation applied in a phase angle adjustment, a control signal (a further control signal) can also be based on a reference value (in an embodiment, the average value of the phase angle observed) of the phase angle adjustment observed in the voltage supplied to the lighting application. Such a control based on a reference value can e.g. be used for controlling an intensity of the LED assembly whereas the control based on the modulation can e.g. be used to control other parameters of the LED assembly (e.g. colour or colour temperature, selecting of subsets of LEDs of the LED assembly, etc....).

These and other aspects of the invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts.

Brief description of the drawings.

Figure 1 schematically depicts a phase adjusted output signal from a conventional AC dimmer circuit.

Figure 2 schematically depicts an embodiment of a lighting application according to the invention.

Figure 3 schematically depicts an embodiment of a user interface device according to the invention.

Figure 4 schematically depicts an example of a phase angle adjusted voltage including a modulation applied to the voltage.

Figure 5 schematically depicts a second example of a phase angle adjusted voltage including a modulation applied to both the trailing and leading edge of the phase angle adjusted voltage.

Description

The present invention relates to controlling LED based lighting applications, in particular to LED based applications supplied from an AC dimmer circuit. AC dimmer circuits such as Triac dimmers are known and are used to provide a phase angle adjusted voltage to a lighting application. Figure 1 schematically depicts such a phase angle adjusted voltage. The dotted line in Figure 1 represents an AC input voltage as e.g. supplied to the dimmer whereas the solid line represents the dimmer output voltage when a firing (or closing) of a Triac of the dimming circuit is delayed by a phase angle α relative to a zero-crossing of the AC supply voltage. By delaying the firing of the dimming circuit, a so-called phase angle adjusted voltage is obtained which is e.g. applied as a supply voltage for a light bulb. As the phase angle adjustment varies the effective value of the output voltage, the power provided to a load (e.g. a light bulb) can vary as well. In case the phase angle adjusted voltage is to be applied to power a LED based lighting application, a power converter is generally applied to convert the phase angle adjusted voltage to a suitable power source for powering the LED or LEDs of the lighting application. In case a phase angle adjusted voltage as shown in Figure 1 is provided as a supply voltage, a rectifier (e.g. a full-bridge diode rectifier) will, in general be provided to rectify the phase angle adjusted voltage. Such a rectifier can e.g. be provided as part of the dimmer circuit or can be part of the power converter. In addition, the power converter can be provided with a buffer (e.g. a capacitor) which can be charged from the rectified voltage.

In accordance with an aspect of the present invention, a modulation is applied to a phase angle adjustment, the modulation being based on an input signal which can e.g. be obtained from a user interface or a sensor. Phrased differently, the phase angle adjustment is modulated, based on an input signal, resulting in a varying (e.g. alternating) phase angle being applied when one or more periods or half periods of the phase angle adjusted voltage are observed. The modulation or variation of the phase angle as applied, is used to provide information or data to a lighting application receiving the modulated phase angle adjusted voltage. The application of the modulation or variation can thus be considered a way of communicating between a dimmer circuit (in general, a user interface device) and a lighting application (that is powered by the dimmer circuit) requiring only the supply voltage to the lighting application. Phrased differently, the information provided (i.e. implemented in the modulation or variation) is comprised in the supply voltage for powering the lighting application. As such, no additional means of communication (e.g. RF communication) needs to be present in either the dimmer circuit or lighting application to communicate information or data (e.g. representing a desired illumination parameter of the lighting application, e.g. obtained from a sensor or user action to a user interface) to the lighting application. The modulation applied to the phase angle adjustment (e.g. implemented by a control unit controlling an electronic circuit of a dimmer, in general, a user interface) can be implemented in various forms, as is explained in more detail below.

The information or data provided by the modulation of the phase angle adjustment can be retrieved and applied in a lighting application according to the invention. Figure 2

schematically depicts an embodiment of a lighting application according to the invention. The lighting application comprises an LED assembly which comprises three LED units 110, 120 and 130 each comprising at least one LED. The lighting application as shown further comprises a power converter 100. The power converter 100, a Buck converter in the embodiment as shown in Figure 2, is supplied from a supply voltage Vsup provided at a terminal of the converter. The supply voltage can e.g. be a phase angle adjusted voltage as e.g. described in Figure 4 below. The lighting application further comprises a control unit CU arranged to control the LED assembly and/or the power converter 100 by means of control signals S1 , S2, S3 and S. The control signals S1 , S2 and S3 as provided by the control unit to the LED assembly can be used to control the current through each LED unit by controlling the switches T1 , T2 and T3 (e.g. MOSFET's). The control signals S1 , S2 and S3 can e.g. short-circuit the resp. LED units 110, 120 and 130 thereby redirecting the current I provided by the converter 100 from the LED units to the resp. MOSFETs T1 , T2 and T3 of the LED assembly. In accordance with the invention, the supply voltage provided to the power converter of the lighting application can e.g. be a rectified phase angle adjusted voltage or an alternating phase angle adjusted voltage wherein the phase angle adjustment comprises a modulation. In the latter case, the power converter can be provided with a rectifier (not shown) to rectify the supply voltage Vsup. In accordance with the invention, the control unit CU of the lighting application as shown further comprises an input terminal INP arranged to receive an input signal SO representative of the supply voltage Vsup, i.e. the modulated phase angle adjusted voltage. From the input signal received, the control unit CU of the lighting application according to the invention can determine a modulation of the phase angle adjustment of the supply voltage. In an embodiment, the power converter is provided with a buffer (e.g. a capacitor) which can be charged from the rectified voltage, in order to obtain a substantially DC supply voltage for the power converter (e.g. a Buck or Boost converter). In such an embodiment, care should be taken to ensure that the modulation as contained in the phase angle adjusted voltage can be retrieved. In such an arrangement, it may be advantageous to retrieve the input signal SO prior to the rectification of the modulated phase angle adjusted voltage or to otherwise isolate components that obscure the phase voltage from the point where the phase is measured. The modulation of the phase angle adjustment (whereby the modulation can be construed as comprising digital of analogue information) can be determined in various ways. As an example, the control unit can be arranged to sample the input signal thereby retrieving the modulation by sampling the input signal during a plurality of periods or half periods, storing the observed phase angle or pulse length applied in the plurality of periods or half periods and determining the modulation. As such, the modulation can e.g. be determined as the difference between an observed phase angle during a first half period and an observed phase angle during a second half period. As an alternative or in addition, the modulation can be determined based on amplitude variations of the input signal at the observed phase angles. In an embodiment, the modulation is determined using both the pulse length or phase angle observed and the corresponding amplitude, thus enabling a more accurate determination of the modulation. In this respect, it is worth noting that a more accurate determination of the modulation enables more information to be provided by the modulation in substantially the same amount of time.

In order to provide a phase angle adjusted voltage to a lighting application whereby the phase angle adjusted voltage comprises a modulation applied to the phase angle adjustment, the present invention provides a user interface device as schematically depicted in Figure 3. Figure 3 schematically depicts a user interface device 300 comprising an electronic circuit 310 for providing a phase angle adjustment to a supply voltage 320 (e.g. a 230 V, 50 Hz AC supply voltage) thereby obtaining a phase angle adjusted voltage 330 which can be provided to a lighting application. The user interface further comprises a control unit 340 for controlling the phase angle adjustment as applied by the electronic circuit. As an example, the electronic circuit can comprise a triac dimmer whereas the control unit controls the moment in time of firing instances within a period of an AC wave-form relative to e.g. a zero-crossing of the AC wave-form, of the triac dimmer thus controlling the phase angle adjustment. In accordance with the invention, the control unit further comprising a terminal 350 for receiving an input signal representative of a desired illumination parameter, the control unit further being arranged to apply a modulation to the phase angle adjustment based on the input signal to obtain a modulated phase angle adjusted voltage and, in use, provide the modulated phase angle adjusted voltage to a lighting application. The input signal representative of a desired illumination parameter can e.g. be provided by a user operation of the user interface device; the user operating a knob or switch or slider or the like of the user interface device. The input signal can also originate from a sensor such as an ambient sensor, a motion detector,.... As such, the input signal may represent various elements of information regarding different kinds of illumination parameters. Examples of such illumination parameters include colour or intensity set-points, commands (e.g. to execute certain pre-programmed light shows), identifiers of one or more LEDs or LED units enabling the control unit of the lighting application to selectively apply/adjust a set-point.

The control unit as applied in the user interface device according to the invention is arranged to receive the input signal and apply, based on the input signal, a modulation to the phase angle adjustment, e.g. apply a modulation to the firing instances of the electronic switches applied in the electronic circuit. As a result, a modulated phase angle adjusted voltage (compared to the voltage without the modulation) is obtained, which can be provided, similar to the provision of the phase angle adjusted voltage, to a lighting application. The modulation as applied can e.g. consist in applying a different (either larger or smaller) phase angle to only the first half period of one or more consecutive periods of the supply voltage, or only to the second half period of one or more consecutive periods, or to both.

In an embodiment, the user interface device according to the invention is arranged to receive a plurality of input signals which can originate from user actions on the user interface device (i.e. a user operating a knob or slider of the interface). In such an embodiment, a first signal, e.g. from operating a dimmer knob in a conventional manner, can be used by the control unit to determine a desired average phase angle in accordance with the position of the dimmer knob. Application of the desired average phase angle could then result in a phase angle adjusted voltage, as e.g. shown in Figure 1 , being provided to a lighting application. Upon receipt of such a phase angle adjusted voltage, e.g. by a power converter of the lighting application, a control unit of the lighting application can e.g. set an intensity of the LED or LEDs of the LED assembly. The other input signals (of the plurality of input signals) as received by the user interface device, can be used by the control unit to determine a modulation and apply the modulation to the phase angle adjustment thus obtaining a modulated phase angle adjusted voltage (compared to the voltage without the modulation). Upon receipt of such a modulated phase angle adjusted voltage (i.e. a phase angle adjusted voltage including a modulation or variation of the phase angle) or a signal representative of such a voltage, a control unit of a lighting application according to the invention can retrieve or determine the modulation and control an LED assembly or power converter of the lighting application based on the modulation or information derived from the modulation. As such, by applying a modulation to the phase angle adjustment, information can be transferred from the user interface device to a lighting application using the voltage as supplied to the lighting application. Phrased differently, information is stored in the modulation applied to the phase angle adjustment, which information can be retrieved by a lighting application and used to control the lighting application.

As mentioned above, the user interface device according to the invention can comprise one or more knobs or sliders or buttons or the like, either analogue or digital (e.g. rotary encoders) for generating (e.g. as a result of a user action) an input signal for the control unit of the user interface whereby the input signal is e.g. converted to an average phase angle adjustment and a modulation of the phase angle adjustment thereby providing/ storing information into a modulated phase angle adjusted voltage.

In an embodiment, the information stored by means of a modulation in the phase angle adjustment can e.g. represent an input received from a sensor, e.g. an ambient light sensor. The information can e.g. be applied to adjust the intensity or colour that was set by a user. As an example, a user can set by application of a dimmer knob or slider, a certain desired brightness or colour in a room provided with a lighting application. In case of a change in conditions outside the room (e.g. it becomes dark or clouded), the brightness or even colour (or colour temperature) inside the room can change. When this change is observed by a sensor (either mounted inside or outside the room), the lighting application can be provided with an adjusted set point for the brightness and/or colour to restore or maintain the brightness and colour as intended by the user. The adjusted set point can, in accordance with the present invention, be provided to the lighting application by applying a modulation in the applied phase adjustment.

The modulation of the phase angle adjustment as retrieved from the phase angle adjusted voltage can be used by the control unit as an analogue signal or can, in a preferred embodiment, be converted to digital data, e.g. representing a desired set point for an illumination parameter of the lighting application. The digital data retrievable from the modulation can be distributed over a plurality of periods or half periods of the phase angle adjusted voltage. To illustrate this, Figure 4 schematically depicts two periods of a phase angle adjusted voltage 400. In Figure 4, it is assumed that the average phase angle observed within one period is the same, said average phase angle being indicated by αθ. As can be seen from figure 4, the actual phase angle applied (phase angles α1 to α4) are not equal to αO; i.e. a modulation is applied to the phase angle adjustment. As can be seen, phase angles α1 and α4 are smaller than αθ whereas α2 and α3 are larger. When such a phase angle adjusted voltage or a signal representative thereof is received by a control unit of a lighting application, this phase angle modulation can be interpreted in a certain way: When a phase angle of a first half period (e.g. a positive voltage) is smaller than an average phase angle and a phase angle of a second half period of the same period is larger than an average phase angle, this can be interpreted as a logical "1 ". When a phase angle of a first half period (e.g. a positive voltage) is larger than an average phase angle and a phase angle of a second half period of the same period is smaller than an average phase angle, this can be interpreted as a logical "0". Using such coding (comparable to the known Manchester coding), one bit of information can be provided during each period of the supply voltage. By appropriate selection of the phase angles α1 to α4, one can ensure that the average phase angle αO can be determined from the average angle observed in two consecutive half period.

As an alternative, the phase angle αO can be applied in each first half period of each period of the voltage and a modulation is only applied to the phase angles of the second half periods. Similar to the example given above, the difference observed between the phase angle of the first half period and the phase angle of the second half period can be interpreted as a logical "1" or a logical "0". In order to improve robustness of the transmitted information, the modulation as determined can be averaged over two or more period or half period. It is acknowledged that this may adversely affect the bit rate which can be obtained. As can be acknowledged, the bit rate as can be obtained by interpreting the modulation of a phase angle adjusted voltage as a logical "1 " or "0" is comparatively low. It will be appreciated by the skilled person that, instead of interpreting the difference in phase angle merely as a logical "1 " or "0", the value of the actual difference, e.g. expressed in microseconds or degrees can be interpreted as a digital number thus enabling more than one bit of information being provided per period.

As an example, by monitoring the supply voltage using one or more comparators, modulations in the supply voltage such as zero-crossings or firing instances can accurately be determined and thus the period expired between such instances, which period can be interpreted as digital information.

To illustrate this, assume a 50 Hz supply voltage is phase angle adjusted by an electronic circuit as applied in a user interface according to the invention and provided to a lighting application according to the invention. Each half period of the voltage provided thus has a duration of 10 ms. In order to retrieve the information contained in the modulation of the phase angle adjustment, the phase angles of subsequent periods or half periods can be determined. Assuming that the phase angle applied in a certain half period can be determined with an accuracy of 10 micro-seconds, one could consider applying a modulation to the phase angle in steps of 25 micro-seconds (either 0, 25, 50 or 75 micro-second) to apply two bits of information during each period of the supply voltage. Due to the repetitive nature of the supply voltage (i.e. having a fixed period of 20 ms) the applied phase angles (and thus the modulation applied to it) can be accurately determined.

When such a two-bit modulation is applied, the modulation applied (e.g. 75 microseconds) remains limited to less than 1 % of the duration of a half period. As will be understood by the skilled person, the more accurate the phase angle can be determined and the larger the applied modulation, the more bits of information can be provided per period of the modulated phase angle adjusted voltage.

In an embodiment, the modulation is applied to both a leading and a trailing edge of the phase angle adjusted voltage. This is illustrated in Figure 5. By applying a phase angle adjusted voltage 400 having a leading and a trailing edge, both edges can be applied in storing information in a similar manner as indicated above. Variations to the angles α1 , α2, α3 or α4 can be assessed as a modulation which can be interpreted as information about a desired illumination parameter. In order to determine the applied modulation, various options exist. As a example, the instance at which the angles α1 , α2, α3 or α4 occur can be determined relative to the instance at which the maximum voltage occurs, indicated by αp in Figure 5. As an alternative, a modulation of the difference between α1 and α2 (α2-α1 ) or between α3 and α4 (α4-α3) may be applied in case the instance at which the maximum voltage occurs is difficult to determine.

In case the phase angle adjustment as applied to e.g. a mains supply voltage is not required for changing an intensity of a lighting application, it may be preferred to use comparatively small firing angles (with respect to a zero-crossing) as such small firing angles only involve small voltage increments and as such may result in less noise compared to conventional use of e.g. a trailing edge or leading edge dimmer. The situation as described may e.g. occur in a retrofit situation whereby an installation comprises a light bulb and a conventional trailing or leading edge dimmer for dimming the light bulb. In such an

arrangement, the phase angle adjustment is required in order to change the intensity of the light bulb. In case the light bulb would be replaced by an LED based lighting application, the supply voltage as provided to e.g. a power converter of the LED based lighting application can remain substantially constant because the intensity is controlled by the LED based lighting application, not by the input voltage. As such, a minimal phase angle adjusted voltage can be supplied which can comprise a modulation representing e.g. a desired intensity set-point.

Referring to the phase angle adjusted voltage as shown in Figure 1 , it may be sufficient to modulate the phase angle α between a first value equal to zero and a second value equal to e.g. a few degrees, sufficient for the LED based lighting application receiving the supply voltage to notice the modulation. By applying such a minimal modulation, voltage increments (either increasing or decreasing) can be kept as low as possible, resulting in a noise reduction compared to conventional dimmers.

In an embodiment, the modulation as applied and resulting in a modulated phase angle adjusted voltage is symmetrical with respect to the phase angle adjustment as applied without the modulation, within one period of the supply voltage. Applying a symmetrical modulation can e.g. consist of increasing the phase angle adjustment of a first half period of the supply voltage by a certain amount and decreasing the phase angle adjustment of a second half period of the supply voltage by essentially the same amount. In such an arrangement, the average of the phase angle of the first half period and the second half period can be determined by the control unit of a lighting application receiving the modulated voltage and can be applied as a reference for determining the modulation. By applying a symmetrical modulation as described, it will be understood that the effective voltage as obtained from the modulated phase angle adjusted voltage will hardly be different from the effective voltage of the phase angle adjusted voltage (i.e. the adjusted voltage without the modulation). In order to obtain an exact match between the effective voltage as obtained from the modulated phase angle adjusted voltage and the effective voltage of the phase angle adjusted voltage, the modulation of a second half period can be selected such that it results in the same effective voltage. Note that this may result in the modulation being slightly un-symmetrical. In such an embodiment, the modulation (as applied e.g. to a first half of a period of the supply voltage) and its contained information, can be determined from comparing the phase angle adjustment that includes the modulation with a phase angle adjustment of a period not including a modulation. As an example, a control unit of the user interface device according to the invention can e.g. alternatingly apply a modulation or not. As an example, the control unit can apply a modulation in a 2^nd, 4^th, 6^th, etc. period and no modulation in the 1^st, 3th , 5^th, etc. period. As such, the average phase angle observed in the 1^st period can be used to determine the modulation applied in the first half period of the second period, etc. As will be appreciated by the skilled person, the modulations that need to be applied in order to provide information to a lighting application to obtain an improved control of the lighting application can be kept comparatively small. As such, the application of such a modulation can be considered not to cause any adverse effects such as flicker, which could cause nausea to certain people. Further, it is worth mentioning that the user interface devices according to the invention remain compatible with more conventional lighting applications which are not equipped to retrieve the information stored in the modulation. The modulation will hardly or will not affect the behaviour of such more conventional lighting applications.

Further advantages of interpreting the modulation as digital information are that the control of the lighting application can be made less dependent on the supply voltage received. The digital information received can e.g. be considered a set point for both colour and intensity of an LED assembly of the lighting application whereby the set point is applied until a next set point is received, regardless the actual supply voltage received. As a result, the effect of a sudden and short power surge, which, in case of a conventional way of controlling, could result in a visible brightness variation of the lighting application, can, at least partly, be avoided as the set point applied is not changed by the power variation. Note that, as mentioned above, a buffer such as a capacitor, e.g. applied between a rectifier and a converter (e.g. a Buck or Boost converter) can be applied to assure the power supply to the power converter.

As already mentioned above, the information provided can e.g. represent a correction to be applied to an illumination parameter based on a sensor output signal received by a user interface.

As a further example, the information provided can be used to selectively change an illumination parameter of a subset of LEDs of the LED assembly. Apart from providing information regarding an illumination parameter to be changed, the information can also include an ID (identifying a single LED or a group of LEDs of an LED assembly) indicating for which LED or group of LEDs the information regarding the illumination parameter is intended.

Also, the information provided can be interpreted by the control unit of the lighting application receiving the information as a command to execute a certain routine or program stored in memory of the control unit or available in a database accessible by the control unit. Such a routine or program can e.g. be a light show. The provided information can also include parameters to such a light show of for performing a routine or program.

As will be appreciated by the skilled person, known digital communication techniques such as the use of headers, use or error-correction protocols may further increase the robustness of the control of a lighting application and result in an improved stability of the illumination provided.

The present invention enables an LED based lighting application to be controlled by retrieving information from a modulation observed in a phase angle adjustment applied in a supply voltage. As the modulated phase angle adjusted voltage contains the information (from which a control signal can be derived), there is no need for other communication channels for controlling the lighting application. By doing so, the application of different means of

communication (e.g. RF communication between a user interface and the lighting application) is no longer required. The design and manufacturing of both the user interface device and lighting application can thus be eased. The design may also be made more compact as no RF- transmitter and receiver are required for providing the lighting application with information to control the lighting application. It is further worth mentioning that there are essentially no increased power requirements to apply the modulation to the phase angle adjustment thereby providing the required information.

Further, when the modulation of the phase angle adjustment is applied symmetrically in a user interface, thereby substantially not affecting the average phase angle, there are essentially no restrictions regarding the use of the user interface according to the invention in combination with lighting applications that are not adapted to retrieve the information from the modulation of the phase angle adjustment.

As required, detailed embodiments of the present invention are disclosed herein;

however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. In particular, the present invention as described employs, as an example, a modulation being applied to a phase angle adjustment of a supply voltage. Such a modulation can be provided by applying components (e.g. electronic switches such as Triacs, MOSFETs, GTOs or the like) already present in known (AC) dimmers. Other forms of modulation such as amplitude modulation (AM) could however be considered as well to include information to the voltage as provided to the power converter. Further, the terms and phrases used herein are not intended to be limiting, but rather, to provide an understandable description of the invention. The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising (i.e., open language, not excluding other elements or steps). Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention.

The mere fact that certain measures or features are recited in mutually different dependent claims does not indicate that a combination of these measures or features cannot be used to advantage.

Claims

1. A method of controlling a lighting application from a user interface device, the lighting

application comprising an LED assembly, a power converter and a control unit for controlling the LED assembly and/or the power converter, the method comprising the steps of

providing, by the user interface device, a phase angle adjustment to a supply voltage, wherein the phase angle adjustment comprises a modulation based on a value of a received input signal representing a desired illumination parameter, thereby obtaining a modulated phase angle adjusted voltage;

providing the modulated phase angle adjusted voltage to the lighting application;

determining, by the control unit, the modulation from the modulated phase angle adjusted voltage and determining a control signal from the modulation;

controlling the LED assembly and/or power converter by the control signal.

2. A lighting application comprising:

- an LED assembly comprising one or more LEDs;

a power converter comprising an input terminal for receiving a modulated phase angle adjusted voltage and an output terminal for providing power to the LED assembly,

determine a modulation from the modulated phase angle adjusted voltage;

- determine a control signal for controlling the LED assembly and/or the power converter to provide in an illumination parameter based on the modulation and provide the control signal to the LED assembly and/or the power converter via an output of the control unit.

3. The lighting application according to claim 2 wherein the control unit is further arranged to

- determine a reference value of the modulated phase angle adjusted voltage and

determine a further control signal for controlling the LED assembly to provide in a further illumination parameter based on the reference value and

- provide the further control signal to the LED assembly via the output of the control unit.

4. The lighting application according to claim 3 wherein the reference value comprises an average of the modulation.

5. The lighting application according to claim 3 or 4 wherein the modulation is determined relative to the reference value.

6. The lighting application according to any of the claims 2-5 wherein the modulation is

determined by sampling the input signal.

7. The lighting application according to any preceding claim wherein the modulation is

converted by the control unit to digital information.

8. The lighting application according to any preceding claim wherein the modulation is

determined by the control unit by monitoring the modulated phase angle adjusted voltage over a plurality of periods or half periods of the input signal representative of the modulated phase angle adjusted voltage.

9. The lighting application according to claim 7 wherein the digital information is distributed over a plurality of periods or half periods of the modulated phase angle adjusted voltage.

10. A user interface device for converting a supply voltage to a modulated phase angle adjusted voltage, the user interface device comprising:

- a control unit for controlling the phase angle adjustment as applied by the

electronic circuit; the control circuit comprising a terminal for receiving an input signal representative of a desired illumination parameter, the control unit further being arranged to control the electronic circuit to provide a phase angle adjustment comprising a modulation based on the input signal, thereby obtaining a modulated phase angle adjusted voltage and, in use, provide the modulated phase angle adjusted voltage to a lighting application.

1 1. The user interface device according to claim 10 wherein the modulation represents digital information.

12. The user interface device according to claim 10 or 1 1 wherein the modulation is

symmetrical with respect to the phase angle adjustment.

13. The user interface device according to any of the claims 10 to 12 wherein the electronic circuit comprises a Triac or MOSFET based dimmer for providing the phase angle adjustment to the supply voltage.

14. The user interface device according to any of the claims 10 to 13 further comprising a user operable device such as a slider or a rotatable knob for providing the input signal in response to a user operation.

15. An illumination system comprising a lighting application according to any of the claims 2 to 9 and a user interface device according to any of the claims 10 to 14, the user interface device being arranged to provide a modulated phase angle adjusted voltage to the lighting application.