WO2024125865A1

WO2024125865A1 - A lamp driving apparatus and a led lamp

Info

Publication number: WO2024125865A1
Application number: PCT/EP2023/079527
Authority: WO
Inventors: Xian Hui GU; Yuming LI; Jianqing Tang; Shangwu Chen; Xiaorong Xing; Yunting Wang; Yang Chen; Hui Li; Minggan LI
Original assignee: Signify Holding B.V.
Priority date: 2022-12-16
Filing date: 2023-10-24
Publication date: 2024-06-20

Abstract

It is proposed a technology to solve the problem that a standalone lamp powered by a standalone lamp driving apparatus is not able to detect in time the interruption of input power to the lamp driving apparatus. It is provided a standalone lamp driving apparatus to be connected to a standalone LED lamp via a wire arrangement, comprising a power input configured to receive an input power; a power conversion circuit to convert said input power into an output power wherein the power conversion circuit comprises a buffer circuit (Cbuff) adapted to buffer said input power and/or said output power; and a power output to be connected with and provide said output power to said LED lamp via a first wire (V48) in the wire arrangement, characterized in that, further comprising a detection circuit adapted to detect a command signal modulated on the input power in a form of an interruption of the input power; and a signal output to be connected with the LED lamp and relay the command signal to the LED lamp, wherein said detection circuit comprises a first opto-coupler (U2) with a light emitting side connected to the power input, and a light receiving side connected to the signal output and adapted to, for relaying the command signal, make the signal output into a first state when powered by the input power, and make the signal output into a second, different, state when not powered at the moment of the interruption of the input power.

Description

A lamp driving apparatus and a LED lamp

FIELD OF THE INVENTION

The present invention relates to the field of LED lighting.

BACKGROUND OF THE INVENTION

Switch off/on configuration is a low cost and convenient way to configure the light output of a lamp. More specifically, the user interrupts and continues the input power into the lamp within a certain time, preferably by switching off and on the hard switch connected between the AC input and the lamp, and the lamp senses such interruption and continuation of its input power, and does the corresponding configuration. For example, the lamp configures its light output brightness or color temperature. Every time such a switch off and on is entered, the lamp swaps to a next configuration in a sequence of configurations.

Such switch off/on configuration has become popular in lamps which directly connects to the AC input. US2019/0082510Aldiscloses such a lamp. But for some lamps that are connected to the AC input via an extra lamp driving apparatus, this is not easy. For example, in track lighting lamps, it is difficult to achieve this function. Because the lamps are connected over a bus and are powered by a high power lamp driving apparatus ACDC (PFC) at a safe low voltage such as 48 V, instead of by the AC directly. And the lamp has a DCDC to convert the 48V voltage to the final LED driving current. As shown in figure 1, the lamp driving apparatus is connected to the AC via a switch operatable by the user. Notably, there are usually some buffer capacitors Cbuir in the lamp driving apparatus, to smooth the AC input power or to smooth the 48V output power to the lamp. In order to stably provide the 48 V output power, the buffer capacitor Cbuir is often very large. Thus even if the user switches off the switch and cut off the input power to the lamp driving apparatus, the buffer capacitor is probably able to maintain the 48V voltage for a substantial time duration, especially when the lamps are working with light-weighted loading, such as low brightness mode. Thus the controller in the lamp is not able to detect an interruption or substantial drop of the 48V output power when the user switches off/on the switch. And therefore the switch off/on configuration is not available for such track lighting system. W02010117340A1 discloses a technology to transmit control signal over AC power lines. A CPU in a receiver circuit decodes a signal on the power lines and transmits the signal to a device under control.

SUMMARY OF THE INVENTION

US2018139823A1 discloses a PoE track interface (PTI) device that connects PoE domain and track light domain. It splits the power and the data of the PoE domain, puts the power on a pair of power conductors on a track light domain, and translate the data into RS485 or DALI protocol on a different pair of communication conductors in the track light domain.

The invention is defined by the claims.

A first idea of the invention is using an opto-coupler directly connected to the input power so as to detect command signal modulated on the input power in a form of an interruption of the input power, the reliability is high and the cost is low compared to the CPU used in WO2010117340A1.

More specifically, in a basic aspect of this first idea, it is provided a standalone lamp driving apparatus to be connected to a standalone LED lamp via a wire arrangement, comprising a power input to receive an input power; a power conversion circuit to convert said input power into an output power wherein the power conversion circuit comprises a buffer circuit adapted to buffer said input power and/or said output power; and a power output configured to be connected with and provide said output power to said LED lamp via a first wire in the wire arrangement, characterized in that, further comprising a detection circuit adapted to detect a command signal modulated on the input power in a form of an interruption of the input power; and a signal output configured to be connected with the LED lamp and relay the command signal to the LED lamp, wherein said detection circuit comprises a first opto-coupler with a light emitting side connected to the power input, and a light receiving side connected to the signal output and adapted to, for relaying the command signal on the second wire, make the signal output into a first state when powered by the input power, and make the signal output into a second, different, state when not powered at the moment of the interruption of the input power.

In this aspect, the driving apparatus detects the interruption of the input power and provide such signal to the LED lamp via a signal wire different from the power wire, thus the LED lamp can still detect the interruption of the input power reliably from the signal wire even when such interruption of input power is not detectable on the power wire, and the switch off/on configuration can be realized. An advantage of the aspect of the invention over WO2010117340A1 is that it uses the input power to directly power an opto-coupler for switching the state of the signal output, thus the state of the signal output is responsive to the input power without needing complex CPU and digital processing to convert. The cost is very low.

In a further embodiment, the signal output is different from the power output and is adapted to be connected with the LED lamp and relay the command signal to the LED lamp, via a second, different, wire in the wire arrangement.

In this embodiment, using an extra signal wire between the driving apparatus and the lamp to communicate a signal of the command modulated over the AC input power which signal is in the form of an interruption (and optionally a subsequent restoration) of the AC input power, and the driver has a circuit to detect this signal and put this signal onto the above extra signal wire. Thus even if the voltage on the power wire between the lamp driving apparatus and lamp does not drop in time when the AC input power is interrupted, the lamp driving apparatus still communicate the signal corresponding to the interruption of the AC input power to the lamp reliably.

In a further embodiment, said buffer circuit is adapted to decouple the interruption of the input power from the output power.

Here “decouple the interruption of the input power from the output power” means that there is no substantial interruption or dip of the output power that is detectable by the LED lamp within a reasonable detection window, when the input power is interrupted. This aspect is especially useful for the applications wherein the LED lamp is not directly connected to AC input power but via a lamp driving apparatus which may smooth the interruption of the AC input power due to buffering.

In one preferred embodiment, the standalone lamp driving apparatus is for a low voltage track lighting system and said power conversion circuit is adapted to provide the output power at a voltage of 12V to 48V.

Track lighting is one example. It should also be noted that there may be other applications with such a problem and the present application can be used too. For example, MR16 lamp application wherein an electronic transformer works as the lamp driving apparatus between the AC input power and the MR16 lamps, and the electronic transformer may also be able to smooth the interruption of the AC input power and therefore there is no interruption or dip of the high frequency AC output power that is detectable by the LED MR16 lamp within the detection window. Alternatively, the lamp driving apparatus could a DC-DC power supply that works in DC grid application.

On the implementation level, in one embodiment, said detection circuit further comprises a first bias supply coupled with said signal output and in parallel with said light receiving side; wherein the first opto-coupler is adapted to be powered by the input power so as to short circuit the first bias supply and the signal output as the first state, and is adapted to decouple from the first bias supply and the signal output as the second state when not powered at the moment of the interruption of the input power.

This embodiment uses opto-coupler to communicate the signal, and the cost is relatively low and it is quite reliable.

In a further embodiment, the input power is AC mains, and the detection circuit comprises a capacitor adapted to keep voltage when the natural zero crossing of the AC mains but lose voltage when the AC mains is manually interrupted.

In this embodiment, the capacitor is used for filtering out the natural zero crossing of the AC mains and prevent mis detecting such natural zero crossing as the manual interruption of the AC mains. Because the manual interruption of the AC mains is much slower than the natural zero crossing, the capacitor works effectively as a low frequency pass filter to pass the manual interruption but blocks the natural zero crossing. A capacitor around lOuF can keep voltage in the natural zero crossing but lose voltage on manual interruption of the AC mains.

In a further embodiment, the detection circuit adapted to detect the command signal modulated on the input power in a form of successive interruption of the input power and a restoration of the input power within a certain delay after the interruption of the input power.

In this embodiment, the successive switching off and on is detected as one command.

Corresponding to the lamp driving apparatus of the first idea, it is also provided a standalone LED lamp to be connected with the standalone lamp driving apparatus via a wire arrangement, comprising a lamp power input configured to be connected to the power output of the lamp driving apparatus and receive the output power from the lamp driving apparatus via a first wire of the wire arrangement, a lighting circuit adapted to emit light by the received output power, and a controller circuit to configure the LED lamp according to a command signal in the form of an interruption of the input power to the lamp driving apparatus, characterized in that, further comprising a signal input, different from the lamp power input, configured to be connected with the signal output of said lamp driving apparatus via a second, different, wire of the wire arrangement and the controller circuit is adapted to receive the command signal relayed by the lamp driving apparatus onto the second wire; wherein the signal input comprises a second opto-coupler with a light emitting side connected to the signal input, and a light receiving side connected with the controller, and adapted to, for providing the command signal to the controller, switch the light receiving side in a first state when powered by a voltage on the signal input and switch the light receiving side into a second, different, state when no voltage on the signal input.

In this embodiment, the lamp senses the interruption of the input power to the lamp driving apparatus not according to the output power from the lamp driving apparatus but according to a relayed signal on a different signal input provided by the lamp driving apparatus. This enables the LED lamp to detect the interruption of the input power to the lamp driving apparatus in case that the output power smooths/hides the interruption of the input power. It provides more controllability to the LED lamp.

Preferably, the standalone LED lamp is a track light. As explained above, the track light usually can not obtain the interruption of the input power to the driver from the output power of the driver in time, thus the present invention can be used to solve this problem. It should be noted that there may be other application of the invention, such as MR16 lamp.

On implementation level, in one embodiment, said signal input further comprises a second bias supply connected with the light receiving side and to the controller; wherein the second opto-coupler is adapted to be powered by a voltage on the signal input so as to short circuit the second bias supply and the light receiving side as the first state, and is adapted to decouple from the second bias supply and the light receiving side as the second state when no voltage on the signal input.

In a further embodiment, the controller is adapted to determine the command based on detection and/or not of a voltage from said second bias supply.

This embodiment provides a low cost and reliable implementation for relaying the command signal.

In one embodiment, said lighting emitting side of the second opto-coupler is bi-polarity and adapted to emit light regardless of the polarity of the voltage on the signal input. This embodiment is not influenced by the connection polarity between the lamp and the lamp driving apparatus, thus provides more freedom to the installation of the lamp driving apparatus and the LED lamp.

In a further embodiment, said controller is adapted to switch a brightness or color temperature according to said command signal.

This embodiment enables the lamp to configure based on switch off/on thus the lamp is more flexible.

Corresponding to the lamp driving apparatus and the lamp, it is also provided a track lighting system comprising the standalone lamp driving apparatus as mentioned above and the standalone LED lamp as mentioned above.

In a further embodiment, the track lighting system further comprises a track arrangement, said track arrangement comprising the first wire, the second wire, and at least one ground wire wherein said at least one ground wire comprising a common ground wire shared by said first wire and the second wire, or two ground wires respectively referred to said first wire and said second wire.

Three wires or four wires track is already popular and widely deployed. Thus the present application utilizes the existing track, and the user can just replace the lamp driving apparatus and the lamp relatively easily and is empowered with the switch off/on configuration for the track lighting, without replacing the track.

The above first idea solves the problem of difficulty in detecting the interruption by adding in the lamp driving apparatus an dedicate signal interface to communicate a signal indicating the interruption. The application also proposes a second idea of the invention to solve this problem from outside of the lamp driving apparatus. More specifically, the second idea is adding a signal relay circuit outside of the lamp driving apparatus, such as in the lamp or also on the track, to sense the interruption by observing the output power of the lamp driving apparatus with a greater sensitivity than that of the lamp. The signal relay circuit then relays the sensed interruption to the lamp by further actively adapting the power into the lamp quickly into a level that the lamp is responsive in time, before the input power continues/restores.

More specifically, it is provided a signal relay circuit to be used between a lamp driving apparatus and a lighting unit, comprising: a receiver adapted to connect to a power input of said lighting unit connected to a power output of the lamp driving apparatus and receive a first signal, from the lamp driving apparatus, indicating an interruption of input power to the lamp driving apparatus, wherein said receiver comprises a voltage detector adapted to detect, as the first signal, a voltage at the power input of the lighting unit below a first threshold level; and a transmitter adapted to connect to the power input of the lighting unit and adapted to relay said first signal to the lighting unit by further pulling down the voltage at the lighting unit.

This embodiment does not need to change the lamp driving apparatus, and does not need a dedicated extra interface between the lamp driving apparatus and the lamp. Thus the cost of deployment is relatively low.

In one embodiment, the receiver is adapted to receive a second signal from the lamp driving apparatus, indicating that the input power to the lamp driving apparatus being continued, wherein the voltage detector is adapted to detect, as the second signal, the voltage at the lighting unit provided by the lamp driving apparatus restores above a second threshold level; and said transmitter is adapted to relay said second signal to the lighting unit by stopping pulling down the voltage at the lighting unit.

In this embodiment, if the output power of the lamp driving apparatus restores, the signal relay circuit would treat this as a continuation of the input power to the lamp driving apparatus, thus the signal relay circuit should relay this continuation of the input power also to the lamp preferably by not pulling down the voltage at the lighting unit and let it restore.

In further embodiments, said second threshold level is equal to the first threshold level. In an alternative embodiment, said second threshold level can be lower than the first threshold level, wherein this can accelerate the signal relaying speed and shorten response time of the LED lamp.

Additionally, the inventors find that, since the lamp may be turned off according to the first signal and stops consuming power from the lamp driving apparatus, the output power of the lamp driving apparatus may rebound because that the lamp driving apparatus still outputs power from its buffered energy even when the input power to the lamp driving apparatus is still interrupted. In order to prevent mis detection due to the rebounded output power of the lamp driving apparatus, the inventors further use a delay control to filter out such rebounded output power of the lamp driving apparatus. More specifically, the signal relay circuit further comprises a delay circuit adapted to keep pulling down the voltage at the lighting unit even if the voltage at the power output of the lamp driving apparatus restores for a delay duration; after the delay duration, if the voltage is still sufficient, it would be considered as a real power on of the lamp driving apparatus, instead of a voltage rebound, and the signal relay circuit can relay the signal to the LED lamp. In one embodiment, the transmitter comprises a switch in parallel with the lighting unit and adapted to become low impedance to pull down the voltage from the lamp driving apparatus to the lighting unit.

In this embodiment, the signal relay circuit shorts circuit the power to the lighting unit so as to notify the lighting unit of the interruption of the input power.

In an alternative embodiment, the transmitter comprises a switch in series between the lamp driving apparatus and the lighting unit and adapted to become high impedance to pull down the voltage from the switch mode power supply to the lighting unit.

In this embodiment, the power path of the lamp driving apparatus is cut off, and the output power of the lamp driving apparatus can be hold thus the lamp driving apparatus can re-start quickly to restore the output power after the input power restores.

In an embodiment, the signal relay circuit can be a standalone device connected on the track connecting the lamp driving apparatus and the lamp.

The advantage of this embodiment is that it can support the traditional lamp driving apparatus, and the lamp with a normal switch off/on detection can be applicable. The cost of implementing is very low.

In an alternative embodiment, the signal relay circuit is embedded into the lamp. It is provided a lamp comprising the signal relay circuit according to above and the lighting unit, wherein the lighting unit comprises a controller coupled to the power input of the lamp and adapted to control the output state of the lighting unit based on the voltage from the lamp driving apparatus relayed by the signal relay circuit.

This embodiment provides a novel lamp.

Alternatively, this signal relay circuit can also be embedded into the lamp driving apparatus.

In a further embodiment, the transmitter can be a double throw device which is adapted to cut off the connection from the lamp driving apparatus and the lighting unit and, simultaneously, create a connection from the lighting unit to a dummy load to discharge the residual energy in the lighting unit. This can further accelerate relaying the interruption signal to the lighting unit reliably.

In a more detailed implementation, the double throw device comprises a driving input connected to the power input, a throw terminal, and two contacts either one of which is to be connected to said throw terminal, said two contacts comprises one normally closed contact to which the throw terminal contacts in case the input power on the power input is absent and one normally open contact to which the throw terminal contacts in case the input power on the power input is present, wherein said throw terminal is adapted to connect to the lighting unit at a first polarity, said normally closed contact is connected to a dummy load connected to the lighting unit at a second polarity, and said normally open contact is adapted to connect to the lamp driving apparatus at the first polarity.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Fig. 1 discloses a state-of-the art track lighting system comprising a lamp driving apparatus, a lamp, and a track with wires connecting the lamp driving apparatus and the lamp;

Fig. 2 discloses a new track lighting system comprising a lamp driving apparatus and a lamp both of which is according to embodiments of the invention, and a track with wires connecting the lamp driving apparatus and the lamp;

Fig. 3 shows the sectional view of a track used in the new track lighting system of figure 2;

Fig. 4 shows a signal relay circuit according to one embodiment of a second idea of the invention;

Fig. 5 a signal relay circuit according to another embodiment of the second idea of the invention; and

Figs 6 and 7 show a signal relay circuit according to yet another embodiment of the second idea of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described with reference to the Figures.

It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

As shown in figure 2, on top of the known powering part, the lamp driving apparatus further comprises a dedicated part for relaying the interruption of the input power to the lamp via an extra signal interface different from the power interface.

More specifically, the lamp driving apparatus’ power part is similar as the present lamp driving apparatus in figure 1, wherein the power part comprises

- a power input to receive an input power, optionally AC mains.

- a power conversion circuit AC -DC to convert said input power into an output power wherein the power conversion circuit comprises a buffer circuit adapted to buffer said input power and/or said output power. In the example, the power conversion circuit has two buffer capacitors Cbuir at the power input for the input power and at the power output for the output power, and

- a power output to be connected with and provide said output power to said LED lamp via a first wire V48 in the wire arrangement. Optionally, there is a ground line Sgnd for this output power.

The most significant improvement over the present lamp driving apparatus in figure 1 is the dedicated part for relaying the interruption of the input power to the lamp, which comprises

- a detection circuit adapted to detect a command signal modulated on the input power in a form of an interruption of the input power; and

- a signal output, different from the power output, to be connected with and relay the command signal to the LED lamp via a second, different, wire Level in the wire arrangement.

More specifically, the detection circuit comprises

- a first opto-coupler U2 with a light emitting side connected to the power input, and a light receiving side connected to the signal output; and

- a first bias supply V3 coupled with said signal output and in parallel with said light receiving side.

When the input power exists, the input power applies on the first opto-coupler U2 via some current/voltage limiting resistors R1 and R11 and voltage limiting Zener diode Dl l. The first opto-coupler is adapted to be powered by the input power, thus the light receiving side is close so as to short circuit the first bias supply V3 and the signal output. In this case, there is no voltage provided by the bias supply V3 onto the second wire Level (referred to the ground Sgnd of the second wire).

When the interruption of the input power occurs, the first opto-coupler U2 is deactivated and its light receiving side is open and adapted to decouple from the first bias supply V3 and the signal output. Thus the first bias supply V3 applies the bias voltage onto the signal output and onto the second wire Level.

For safety reasons, the voltage of the first bias supply V3 is lower than 48V.

In a more detailed embodiment, in order to differentiate a natural zero crossing of the sinuous AC mains from the manual interruption of the AC mains, the detection circuit further comprises a capacitor Cniter adapted to keep voltage when the natural zero crossing of the AC mains but lose voltage when the AC mains is manually interrupted. The capacitor acts as a low frequency filter: only a manual interruption with low frequency such as several Hz can pass the capacitor and deactivate the opto-coupler U2 but a 50/60Hz natural zero crossing of the AC mains is filtered out and can not deactivate the opto-coupler. The capacitance of the capacitor Cniter is for example lOuF.

Figure 3 shows the wires/conductors in the track to be used in the embodiment of the present invention. It is a four-conductors track. The two conductors on the upper side serve as the second wire Level and its ground Sgnd. The two conductors on the lower side serve as the first wire V48 and its ground Sgnd. Here the power part and the relaying part share a same ground Sgnd thus the two conductors of Sgnd can be combined into one and a three-conductors track can be used instead. In an alternative embodiment, the power part and the relaying part have different grounds and the shown four-conductors track is necessary.

Going back to figure 2, the present invention also provides a standalone LED lamp to be connected with the standalone lamp driving apparatus via the wire arrangement. The provided LED lamp also comprises a power part that is similar with the known lamp, but comprises a new signal receiving part to receive the signal of the interruption of the input power relayed by the lamp driving apparatus on the extra interface.

More specifically, the power part of the lamp comprises a lamp power input adapted to connect to the power output of the lamp driving apparatus and receive the output power from the lamp driving apparatus via the first wire V48 and a lighting circuit adapted to emit light by the received output power. The lamp also comprises a controller circuit to configure the LED lamp according to a command signal in the form of an interruption of the input power to the lamp driving apparatus. Notably, the new signal receiving part of the lamp comprises a signal input, different from the lamp power input, to be connected with the signal output of said lamp driving apparatus via a second wire Level of the wire arrangement and the controller circuit is adapted to receive the command signal relayed by the driving apparatus onto the second wire Level.

On implementation level, in one embodiment, said signal input of the lamp comprises a second opto-coupler U1 with a light emitting side connected to the signal input, and a light receiving side connected with the controller (not shown) on terminal AC detection and a ground SXGND in the lamp; and a second bias supply V5 of 3.3V connected with the light receiving side and to the controller.

When the lamp driving apparatus provides the V3 voltage when the input power is interrupted as mentioned above, the second opto-coupler U1 is adapted to be powered by such V3 voltage so as to short circuit the second bias supply V5 and the light receiving side. Thus the controller senses no voltage between the terminal AC detection and the ground SXGND, and the controller can determine an interruption of input power occurs. When no voltage on the signal input provided by the lamp driving apparatus in case that the input power exists, the second opto-coupler U1 decouples from the second bias supply V5 and the light receiving side and the second bias supply V5 applies voltage between the terminal AC detection and the ground SXGND. The controller senses voltage between the terminal AC detection and the ground SXGND, and the controller can determine input power being existing.

In real track lighting system, it is preferably polarity insensitive so as to provide the installer a freedom to install the lamp in arbitrary direction. Thus the lamp has better to receive the signal wire Level and its ground Sgnd in either positive orientation as well as negative orientation. To support this, in one embodiment, said lighting emitting side of the second opto-coupler U1 is bi-polarity and adapted to emit light regardless of the polarity of the voltage on the signal input.

In a further embodiment, in order to realize switch off/on configuration, said controller is adapted to switch a brightness or color temperature according to said command signal. The sequence of the switching brightness could be high brightness, medium brightness and low brightness, wherein the controller controls the DCDC converter in the lamp to provide a large current, medium current and small current to the LED unit. The sequence of the switching color temperature could be cold color temperature, medium color temperature and warm color temperature, wherein the controller can select only cold color temperature LED, both cold and warm color temperature LED, and only warm color temperature LED is powered by the DCDC converter. The brightness and the color temperature can be changed together also.

Figures 4 and 5 disclose embodiments according to a second idea of the invention. The second idea is adding a signal relaying circuit preferably outside of the lamp driving apparatus, and the signal relaying circuit is adapted to actively relay the interruption of the input power to the lamp driving apparatus on the power interface between the lamp driving apparatus and the lamp.

As shown in figure 4, a signal relay circuit is connected between the lamp driving apparatus and the lighting unit. The signal relay circuit comprises; a receiver adapted to connect to a power input of said lighting unit connected to a power output of the lamp driving apparatus. As shown in figure 4, this receiver is connected to the power wire V48 between the lamp driving apparatus and the lamp. The receiver is adapted to receive a first signal, from the lamp driving apparatus, indicating an interruption of input power to the lamp driving apparatus, wherein said receiver comprises a voltage detector adapted to detect, as the first signal, a voltage at the power input of the lighting unit below a first threshold level; and a transmitter adapted to connect to the power input of the lighting unit and adapted to relay said first signal to the lighting unit by further pulling down the voltage at the lighting unit.

The receiver substantially comprises a resistor R6, a transistor QI, and a capacitor C3. The resistor R6 is connected between the power wire V48 and the base of the transistor QI. The capacitor Cl is connected to the collector of the transistor QI. The emitter of the transistor QI is connected to the power wire V48 via some current/voltage limiting components R8, DI and D2. The collector of the transistor QI is connected to the base of a transistor Q2. The transmitter comprises the transistor Q2. The collector/emitter of the transistor Q2 is connected between the power wire V48 and ground, and is in parallel with the lamp.

The current/voltage limiting components R8, DI and D2 and capacitor C3 are sized such that the capacitor C3 is charged into a first voltage threshold by the 48V normal output voltage of the lamp driving apparatus. For example, the forward voltage of the diode DI is 0.7V and the breakdown voltage of the Zener diode D2 could be 3 V, making the voltage on the capacitor C3 being 48V-0.7V-3V=44.3V.

When the AC input power to the lamp driving apparatus is interrupted by the switch, the output voltage of the lamp driving apparatus begins to drop. When it drops below 44.3V-0.7V (emitter-base voltage of the transistor QI) = 43.6V, the transistor QI becomes conductive, and pulls high the base of the switch Q2 in the transmitter. Wherein the capacitor Cl can smooth the base voltage of the switch Q2 and the resistor R7 can limit the current to the base of the switch Q2.

The switch Q2 becomes conductive and pulls down the voltage on the power wire V48 to a level that the lamp is responsive to implement the switch off/on configuration. For example, the MCU in the lamp will be power off and the MCU would count this is a switch off. The resistor R3 is for limiting the pulling down current.

When the AC input power to the lamp driving apparatus continues/restores, the output voltage of the lamp driving apparatus begins to increase. When it increases above 43.6V, the transistor QI becomes non-conductive. The base of the switch Q2 in the transmitter would discharge via R7 and Cl, and the switch Q2 becomes non-conductive. The voltage on the power wire V48 would restore and restart the MCU in the lamp. The MCU in the lamp would count this is a switch on, and start to configure the lamp based on this switch off/on, for example swap to a next light output state in a sequence.

In the above embodiment, in order to relay the interruption of the input power, the transmitter is a switch in parallel with the lamp and becomes low impedance to short circuit the power wire V48 so as to make the voltage across the lamp become zero. In an alternative embodiment, the transmitter could be a switch in series with the lamp and become high impedance so as to make the voltage across the lamp become zero. Figure 4 shows this alternative embodiment, wherein the block Part A is adapted to can detect the drop of the output power of the lamp driving apparatus. Part B is a hysteresis control circuit introduced later. Part C is the switch in series with the lamp.

More specifically, Part A comprises a transistor QI, a diode DI, a Zener diode D2, a resistor R1 and a capacitor C3 which are similar as those in figure 3. The capacitor C3 is charged to about 48-0.7 = 47.3V. The transistor QI is adapted to compare the output voltage of the lamp driving apparatus and the voltage on the capacitor C3. If it drops and lower than voltage of the capacitor C3, the transistor QI will turn on and trigger the transistor Q2 turn on and make the transistor Q5 as the switch to be off. Then the lamp will disconnect with the output power of the lamp driving apparatus immediately and the MCU in the lamp can power off and record this switch off configuration.

In one embodiment, in order to accelerate the response speed of the relay circuit, the threshold for determining the power up of the lamp driving apparatus can be different from/lower than the threshold for determining the power off of the lamp driving apparatus. The Zener diodes D5 and D4, the capacitor Cl and the resistor R6, and transistor Q4 achieve this. It is set to make the transistor Q2 off when the voltage of the output power restores and increases above a second threshold such as 45 V lower than 47.3 V. The Zener diodes D5 and D4 break down when the output voltage increases above 45 V, and the capacitor Cl and the resistor R6 charge and turn on the transistor Q4. The transistor Q4 turns off the transistor Q2, and the MOSFET Q5 restores to conductive state so that the lamp is reconnected to the output voltage V48.

In a further embodiment, there may be some energy buffered at the input of the lamp driving apparatus. And when the lamp is cut off from the lamp driving apparatus, the lamp driving apparatus is till converting the buffered energy into the output power, thus the voltage of the output power may even rebound back even if the lamp driving apparatus is cut off from the input power since the load has been cut off In this case, such rebound should not be treated as the continuation of the input power to the lamp driving apparatus. To filter such event out, one embodiment of the invention can use the capacitor Cl to provide a timebased filtering: when the voltage is high to trigger the Zener diodes D5 and D4, it has to stay for a while to charge the capacitor Cl; if it is just a rebound, it is considered that the rebound can not last for enough time to charge the capacitor Cl to the sufficiency level to turn on the transistor Q4. Therefore such rebound can be filtered out. If it is a continuation of the input power, it can last sufficiently long to charge the capacitor Cl to the sufficiency level to turn on the transistor Q4.

Figure 6 shows another embodiment wherein the switch in series between the driving apparatus and the lighting unit is put inside driving apparatus. The switch is implemented by an AC-driven relay and this relay is double throw which is adapted to cut off the connection from the lamp driving apparatus and the lighting unit and, simultaneously, create a connection from the lighting unit to a dummy load to discharge the residual energy in the lighting unit. This can further accelerate relaying the interruption signal to the lighting unit reliably.

In a more detailed implementation, the double throw device comprises a driving input A1/A2 connected to the power input L/N, a throw terminal 11, and two contacts either one of which is to be connected to said throw terminal 11, said two contacts comprises one normally closed contact 12 to which the throw terminal 11 contacts in case the input power on the power input is absent and one normally open contact 14 to which the throw terminal contacts in case the input power on the power input is present. Wherein said throw terminal 11 is adapted to connect to the lighting unit at a first polarity for example positive polarity, said normally closed contact 12 is connected to a dummy load connected to the lighting unit at a second polarity for example negative polarity, and said normally open contact 14 is adapted to connect to the lamp driving apparatus at the first polarity.

Figure 6 shows the current flow when the input power on the power input is present. The positive current goes via the contact 14 to the terminal 11 and to the lighting unit, and returns from the negative line.

Figure 7 shows the connection when the input power on the power input is absent/interrupted. Because of the absence of the input power, the relay is not powered and the throw 11 decouples from the contact 14 and couples to the contact 12. The current from the power supply to the lighting unit is cut off. Even more, the dummy load is connected in parallel to the lighting unit instead, and it discharges the residual energy at the lighting unit so that the lighting unit is aware of the interruption of the input power more quickly.

Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

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

If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A standalone lamp driving apparatus to be connected to a standalone LED lamp via a wire arrangement, comprising

- a power input to receive an input power;

- a power conversion circuit to convert said input power into an output power wherein the power conversion circuit comprises a buffer circuit (Cbuff) adapted to buffer said input power and/or said output power; and

- a power output configured to be connected with and provide said output power to said LED lamp via a first wire (V48) in the wire arrangement, characterized in that, further comprising

- a signal output configured to be connected with the LED lamp and relay the command signal to the LED lamp; wherein said detection circuit comprises a first opto-coupler (U2) with a light emitting side connected to the power input, and a light receiving side connected to the signal output and adapted to, for relaying the command signal, make the signal output into a first state when powered by the input power, and make the signal output into a second, different, state when not powered at the moment of the interruption of the input power.

2. The standalone lamp driving apparatus according to claim 1, wherein the signal output is different from the power output and is adapted to be connected with the LED lamp and relay the command signal to the LED lamp, via a second, different, wire in the wire arrangement.

3. The standalone lamp driving apparatus according to claim 2, wherein said buffer circuit (Cbuff) is adapted to decouple the interruption of the input power from the output power.

4. The standalone lamp driving apparatus according to claim 1, wherein the standalone lamp driving apparatus is for a low voltage track lighting system and said power conversion circuit is a power factor correction circuit adapted to provide the output power at a voltage of 12V to 48V.

5. The standalone lamp driving apparatus according to claim 4, wherein said detection circuit further comprises

- a first bias supply (V3) coupled with said signal output and in parallel with said light receiving side; wherein the first opto-coupler (U2) is adapted to be powered by the input power so as to short circuit the first bias supply (V3) and the signal output as the first state, and is adapted to decouple from the first bias supply (V3) and the signal output as the second state when not powered at the moment of the interruption of the input power.

6. The standalone lamp driving apparatus according to claim 5, wherein the input power is AC mains, and the detection circuit comprises a capacitor (Cniter) adapted to keep voltage at the natural zero crossing of the AC mains but lose voltage when the AC mains is manually interrupted.

7. The standalone lamp driving apparatus according to claim 1, wherein the detection circuit adapted to detect the command signal modulated on the input power in a form of successive interruption of the input power and a restoration of the input power within a certain delay after the interruption of the input power.

8. A standalone LED lamp to be connected with the standalone lamp driving apparatus according to claim 7 via a wire arrangement, the standalone lamp comprising:

- a lamp power input configured to be connected to the power output of the lamp driving apparatus and receive the output power from the lamp driving apparatus via a first wire (V48) of the wire arrangement,

- a lighting circuit adapted to emit light by the received output power, and

- a controller circuit to configure the LED lamp according to a command signal in the form of an interruption of the input power to the lamp driving apparatus, characterized in that, further comprising a signal input, different from the lamp power input, configured to be connected with the signal output of said lamp driving apparatus via a second, different, wire of the wire arrangement and the controller circuit is adapted to receive the command signal relayed by the lamp driving apparatus onto the second wire; wherein the signal input comprises a second opto-coupler (Ul) with a light emitting side connected to the signal input, and a light receiving side connected with the controller, and adapted to, for providing the command signal to the controller, switch the light receiving side in a first state when powered by a voltage on the signal input and switch the light receiving side into a second, different, state when no voltage on the signal input.

9. The standalone LED lamp according to claim 8, wherein the standalone LED lamp is a track light.

10. The standalone LED lamp according to claim 8, wherein said signal input further comprises a second bias supply (V5) connected with the light receiving side and to the controller; wherein the second opto-coupler (Ul) is adapted to be powered by a voltage on the signal input so as to short circuit the second bias supply (V5) and the light receiving side as the first state, and is adapted to decouple from the second bias supply (V5) and the light receiving side as the second state when no voltage on the signal input.

11. The standalone LED lamp according to claim 10, wherein the controller is adapted to determine the command based on detection and/or not of a voltage from said second bias supply.

12. The standalone LED lamp according to claim 10, wherein said lighting emitting side of the second opto-coupler is bi-polarity and adapted to emit light regardless of the polarity of the voltage on the signal input.

13. The standalone LED lamp according to claim 8, wherein said controller is adapted to switch a brightness and/or color temperature according to said command signal

14. A track lighting system comprising the standalone lamp driving apparatus according to claims 2, and the standalone LED lamp according to any one of claims 8 to 13.

15. The track lighting system according to claim 14, further comprising a track with a first conductor rail, a second conductor rail, and a third conductor rail, wherein said first conductor rail is adapted to serve as the first wire, the second conductor rail is adapted to serve as the second wire, and the third conductor rail is adapted to serve as a ground for either one or both of the first and the second wires.