WO2013084125A1

WO2013084125A1 - A module and electronic circuitry comprising a light emitting diode

Info

Publication number: WO2013084125A1
Application number: PCT/IB2012/056858
Authority: WO
Inventors: Michel Cornelis Josephus Marie Vissenberg; Redouane Eddeane
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2011-12-08
Filing date: 2012-11-30
Publication date: 2013-06-13

Abstract

A module comprises first inductor portion (12A), second inductor portion (12B), and at least one light emitting diode (10), the first inductor portion, the second inductor portion and the at least one light emitting diode being arranged such that the module is operable to receive electrical energy wirelessly via the first inductor portion from a third inductor portion, is operable to route current through the at least one light emitting diode, and is operable to transmit electrical energy wirelessly via the second inductor portion to a fourth inductor portion. A plurality of such modules may be contained within a translucent portion, which may be a translucent filler material, to form a lighting system. Electronic circuitry comprises a first set of electrical components (20)connected in parallel with a second set of electrical components (22), the first set of electrical components including at least one light emitting diode (10) and a resistor (24) in series and the second set of electrical components including at least one diode, wherein the first set of electrical components is configured to conduct current only when a voltage across the first and second sets of electrical components is above a first level, wherein the second set of components is configured to conduct current only when a voltage across the first and second sets of electrical components is above a second, higher level, and wherein, when the voltage across the first and second sets of electrical components is at a third level higher than the second level, the resistance of the first set of electrical components is higher than the resistance of the second set of electrical components, such that the current-voltage curve of the second set of components intersects the current-voltage curve of the first set of components when the voltage is at the third level.

Description

A module and electronic circuitry comprising a light emitting diode

FIELD OF THE INVENTION

The invention relates to a module comprising a light emitting diode and to electronic circuitry comprising a light emitting diode. BACKGROUND OF THE INVENTION

The availability of light emitting diodes (LEDs) that are suitable for general illumination purposes allows for the use of LED light sources in many different scenarios. Designers all over the world are currently investigating new designs that are made possible by the small form factor and low- voltage driving of LEDs. These features enable easy integration of LED light sources in the interior (ceilings, walls, carpet), into furniture or tools, or even embedding into materials like plastics, glass, silicone and concrete.

An important limitation for embedding LEDs into a material is that they require power. Usually, the power is supplied by a fixed wire or a fixed wire grid. This is a flexible solution, but it requires a redesign of the wiring structure for each new object shape, which increases the cost and the time-to-market. There is therefore a need for a solution to these problems.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a module comprising first inductor portion, second inductor portion, and at least one light emitting diode. The first inductor portion, the second inductor portion and the at least one light emitting diode are arranged such that the module is operable to receive electrical energy wirelessly via the first inductor portion from a third inductor portion, is operable to route current through the at least one light emitting diode, and is operable to transmit electrical energy wirelessly via the second inductor portion to a fourth inductor portion. The third inductor portion is part of a first, substantially identical neighboring module and the fourth inductor portion is part of a second, substantially identical neighboring module. If a plurality of such modules are incorporated into an object and one of the modules is inductively coupled with a power supply, then electrical energy can percolate through the modules in the object thereby activating the light emitting diodes in the modules. This eliminates the need for a bespoke, or indeed any, wiring pattern to be incorporated into the object and so the manufacture costs associated with the object may be reduced and the freedom of design and ease of manufacture of the object may be increased.

The module may comprise a first set of electrical components connected in parallel with a second set of electrical components, the wireless receipt of electrical energy via the first inductor portion causing a voltage to be applied across the first and second sets of electrical components. The first set of electronic components includes the at least one light emitting diode and the second set of electrical components includes at least one diode. The first set of components is configured to conduct a significant current only when a voltage across the first and second sets of electrical components is above a first level. The second set of components is configured to conduct a significant current only when a voltage across the first and second sets of electrical components is above a second, higher level. When the voltage across the first and second sets of electrical components is at a third level, higher than the second level, the resistance of the first set of electrical components is higher than the resistance of the second set of electrical components, such that the current-voltage curve of the second set of components intersects the current- voltage curve of the first set of components when the voltage is at the third level. This provides current protection for the at least one light emitting diode in each module such that the current that is able to flow through the at least one light emitting diode is limited to a maximum value, regardless of the voltage applied across the first and second sets of components. This ensures longevity of the light emitting diode and also allows more energy to be passed on to other modules.

The first set of electrical components may comprise a resistor in series with the light emitting diode. This provides a more reliable and stable current protection. In addition, the presence of the resistor makes it easier to accurately set the maximum current that is allowed to flow through the light emitting diode.

At least one diode of the second set of components may comprise a Zener diode. The second set of components may comprise a plurality of diodes connected in series. The second set of components may comprise a light emitting diode and a diode connected in series.

The first and second inductor portions may be connected to the light emitting diode via a bridge rectifier. This allows a DC current to be provided to the light emitting diode. The module may comprise a translucent body with the first and second inductor portions and the light emitting diode being provided within the translucent body.

The first inductor portion may comprise a first inductor coil and the second inductor portion may comprise a second inductor coil, wherein the first and second inductor coils are provided at opposing sides of the module. This is beneficial for the propagation of electrical energy between modules.

In a second aspect, the invention provides electronic circuitry comprising a first set of electrical components connected in parallel with a second set of electrical components, the first set of electrical components including at least one light emitting diode and a resistor in series and the second set of electrical components including at least one diode. The first set of electrical components is configured to conduct a significant current only when a voltage across the first and second sets of electrical components is above a first level. The second set of components is configured to conduct a significant current only when a voltage across the first and second sets of electrical components is above a second, higher level. When the voltage across the first and second sets of electrical components is at a third level higher than the second level, the resistance of the first set of electrical components is higher than the resistance of the second set of electrical components, such that the current- voltage curve of the second set of components intersects the current-voltage curve of the first set of components when the voltage is at the third level. This arrangement provides protection for the light emitting diode against damage due to high currents. This helps to ensure the longevity of the light emitting diode.

The electronic circuitry may be part of a module, the module further comprising first and second electrical energy transfer portions, the first electrical energy transfer portion being operable to receive electrical energy from an electrical energy transfer portion of a first neighboring module and the second electrical energy transfer portion being operable to transfer energy to an electrical energy transfer portion of a second, neighboring module, wherein the first and second electrical energy transfer portions are connected to the electronic circuitry such that receipt of electrical energy via the first electrical energy transfer portion causes a voltage to be applied across the first and second sets of electrical

components. A plurality of modules in accordance with either of the first or second aspects may be contained within a translucent portion to form part of a lighting system. Such a lighting system does not require a bespoke, or indeed any, wiring pattern to be provided between the light emitting diodes modules.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of embodiments of the present invention, reference is now made to the following description taken in connection with the

accompanying drawings in which:

Figs. 1A and IB are illustrative depictions of a composite material in accordance with aspects of the invention;

Fig. 2 is a circuit diagram of module according to aspects of the invention;

Fig. 3 is a graph illustrating the operation of aspects of the invention;

Figs. 4A to 4D are various alternatives for electronic components that may form part of the module of Fig. 1 ;

Fig. 5 is schematic illustration of a system comprising a plurality of modules as shown is Fig. 1;

Figs. 6 to 8 are graphs illustrating operations of part of the system of Fig. 5; and

Fig. 9 is an illustrative schematic of the physical structure of the module of

Fig. 1.

DETAILED DESCRIPTION

In the description and drawings, like reference numerals refer to like surface electrodes throughout.

Figs. 1 A and IB illustrate how the invention makes use of the physical effect known as "percolation". Specifically, the invention makes use of percolation of electrical energy along randomly- formed paths in an insulating filler material.

Fig. 1 A shows a composite material 3 including a relatively low number of discrete light emitting diode (LED) modules 1 distributed, or embedded, within an translucent, insulating filler (or bulk) material 2. The LED modules 1 are discrete in the sense that, before being mixed with the insulating filler material 2 to form the composite material they are separate from one another. The LED modules 1 are unconnected by wires or the like. Although not visible in Fig. 1 A, each of the LED modules 1 comprises at least one LED and first and second electrical energy transfer portions. The first and second electrical energy transfer portions may also be referred to an electrical energy transfer means, in some cases, elements. When the modules 1 are in close enough proximity they are able to transfer electrical energy from one module 1 to another such that electrical energy propagates along a path of proximate modules. As such, the LED of each LED module 1 in the path is illuminated. This, in turn, causes the composite material 3 to emit light.

In the composite material 3 of Fig. 1A, the number of LED modulesl per unit volume of composite material may be too low. As such, each module 1 or group of neighboring modules 1 embedded in the filler material is isolated from the other modules 1 by the insulating filler material 2. As such, it is not possible for electrical energy to pass between the modules 1 of different groups. In other words, percolation of electrical energy throughout the composite material 3 of Fig. 1A is not possible.

However, when the number of LED modules 1 per unit volume of composite material reaches a threshold, known as the "percolation threshold", the whole volume of the composite material 3 is spanned with a network of randomly- formed paths along which electrical energy is able to propagate. These paths are made up by strings of neighboring LED modules 1, with electrical energy being passed from one module 1 to its neighbor.

A composite material 3 in which the percolation threshold has been surpassed is shown in Fig. IB. In Fig. IB, a plurality of different paths of LED modules 1 have been formed throughout the volume of the composite material 3. This enables the propagation throughout the material of electrical energy for activating the LEDs of the LED modules throughout the material. As such, the composite material shown in Fig. IB may be referred to as a lighting system. Three of these paths are denoted by the dotted lines labeled PI to P3. As can be seen from paths P2 and P3, some LED modules 1 may be members of plural different strings. The percolation threshold usually occurs when the aggregate volume of the LED modules 1 constitutes 25-50% of the volume of the composite material 3. However, this depends on the characteristics of the LED modules 1. More commonly, the percolation threshold falls within the range of 30-40%. In this specification, the volume of each LED module 1 may not necessarily be its actual physical volume, but instead refers to the volume, centered on the module 1, within which neighboring modules must be in order for the module 1 to be able to pass electrical energy to, and to receive electrical energy from, the neighboring modules. The lighting system 3 of Fig. IB may be created by mixing the discrete LED modules 1 with the translucent, insulating filler material 2. Subsequently, the material 3 can be moulded and set into any desired shape. If energy is supplied to the paths of LED modules 1, the modules 1 within the paths are activated (i.e. are caused to emit light). As the insulating filler material 2 is translucent, the moulded object as a whole emits light.

The insulating filler material is translucent such that light is able to pass through it. In this specification, translucency is to be understood as including transparency. The insulating filler material 2 may be a solid. The insulating filler material may be thermosetting, or an otherwise hardening or setting, solid. The insulating filler material may comprise, for example, glass, a resin, silicone, a plastic such as poly(methyl methacrylate) (PMMA), polycarbonate (PC) or polyethylene terephthalate (PET). The material 2 may alternatively be an insulating material having a relatively low translucency, such as gypsum (plaster) or paper with transparent glue (papier-mache). The insulating filling material may be referred to as a module-containing portion of the lighting system, in the sense that it contains the modules.

The composite 3 may contain additional materials to obtain a specific light effect. For example, Titanium Oxide particles may be included to tune the degree of transparency (specifically, a higher density of titanium oxide results in more scattering and so less transparency). Similarly, pigments may be included to obtain a certain color or colored or reflective flakes or beads may be included to provide a sparkling effect.

Alternatively, the filler material 2 may be a fluid (for example oil, silicone oil or silicone grease) or a gas (for example air) inside a shell or container. This allows for a dynamic formation of paths, which results in paths along which electrical energy can travel, which can be changed by shaking the shell or container, or by gravity over time. In these alternative examples, the container or shell may be referred to as the module-containing portion.

Fig. 2 is a schematic circuit diagram of an LED module 1 according to various aspects of the invention. The module 1 is operable to receive electrical energy, or power, from a first, substantially identical neighboring module (not shown), to route at least some of that electrical energy through at least one light emitting diode (LED) 10 thereby activating the LED 10, and to transfer some of the received electrical energy to a second, substantially identical neighboring module (also not shown). The module 1 is operable to receive electrical energy from, and to transfer electrical energy to, the substantially identical neighboring modules without the need for conjoining wires. The module comprises first and second electrical energy transfer portions 12A and 12B. Electrical energy is transferred to and from the neighboring modules via the electrical energy transfer portions 12A and 12B.

In the specific example of Fig. 2, the module 1 comprises electronic circuitry 14 to which electrical energy is routed when it is received at the module 1. The electronic circuitry comprises first and second branches 16, 18 which are in parallel connection with one another. The first branch 16 comprises a first set of electronic components 20 and the second branch 18 comprises a second set of electronic components 22.

The first set of components 20 comprises at least one LED 10. The second set of components 22 comprises at least one diode (not shown in Fig. 2). The first set of components 20 is operable to conduct a significant amount of electrical current only after a voltage across the first and second branches 16, 18 surpasses, or exceeds, a first

predetermined level or threshold. Prior to the voltage exceeding the first level, the first set of components 20 does not conduct a significant amount of electrical current. Below the first level, a very small "leakage current" may be conducted due to the non-ideal nature of the LED 10, but this current is insufficient to cause the LED 10 to emit light. The second set of components 22 is operable to conduct a significant amount of electrical current only after a voltage across the first and second branches 16, 18 surpasses a second predetermined level or threshold. The second level is higher than the first level. The second set of components 22 does not conduct current when the voltage across the first and second branches 16, 18 is lower than the second level. Below the second level, a very small "leakage current" may be conducted as a result of the non-ideal nature of the at least one diode. Consequently, when the voltage is between the first and second thresholds, a significant current only passes through the first set of components 20, and not through the second set of components 22. When the voltage is above the second threshold, significant currents flow through both the first and second sets of components 20, 22.

The first and second sets of components 20, 22 are selected such that, when the voltage across the first and second branches 16, 18 is at a third level, higher than the second level, the overall resistance of the second set of components 22 is lower than the overall resistance of the first set of components 20. The effect of this is that, when the voltage is at or above the third level, the majority of the current due to the voltage will flow through the second set of components 22, with only a substantially constant current flowing through the first set of components 20. As such, regardless of the voltage, only a limited current will flow through the light emitting diode 10. Consequently, if the predetermined current is selected correctly, the life of the LED 10 will not be compromised by large increases in electrical energy arriving at the module 1. In addition, as only a low amount of electrical energy is used to light the LED 10, more energy can be transferred from the module 1 to the subsequent modules in the path (not shown).

In the example of Fig. 1, the first set of components 20 comprises a resistor 24 in series with the LED 10. The resistance of the resistor 24 is selected based on the maximum current that that is desired to flow through the LED 10.

Fig. 3 is a graph showing the current- voltage (IV) curves of the first and second sets of components 20, 22. An IV-curve depicts how the current flowing through a set of components varies with varying voltage. A first curve CI shows the current that flows through an exemplary first set of components 20 as the voltage increases. The first set of components 10 comprises the LED 10 and, as such, no current (or only an insignificant "leakage current") is able to flow through the first set of components 20 until the voltage across the first set reaches the first level or threshold value (denoted V_TI). The voltage level at which an LED 10 begins to conduct current is commonly known as the "forward voltage" of the LED. After this point, instead of the current increasing exponentially with increasing voltage (as is shown by the curve marked C3), the resistor 24 has the effect of making the current increase more gradually with increasing voltage, with a gradient the curve being substantially equal to 1/R, where R is the resistance of the resistor 24.

The IV-curve for the second set of components 22 is shown by the curve marked C2. As mentioned above, the second set of components 22 includes one or more diodes. Current only flows through the second set of components 22 after the voltage reaches the second level V_T2. The second level V_T2 is dependent on the forward voltages of the one or more diodes of which the second set of components 22 is comprised, and also the way in which the one or more diodes are arranged. Soon after the voltage surpasses the second level V_T2, the resistance of the second set of components 22 is reduced to less than the resistance of the first set of components 20. This can be seen by the fact that the gradient of the IV curve C2 of the second set of components 22 is significantly steeper than the gradient of the IV curve CI of the first set of components. As such, at the third voltage level V_T3, the IV curve C2 of the second set of components 22 crosses the IV curve CI of the first set of components 20. This crossing point determines the maximum current I_M that will flow through the first set of components 20, which includes the LED 10.

In the example illustrated in Fig. 3, the second set of components 22 is constituted only by one or more diodes, and includes no components with any substantial resistance (after the voltage surpasses the second level V_T2). Consequently, after the second voltage level V_T2 is surpassed, the IV curve C2 rises exponentially. In other words, the resistance of the second set of components 22 quickly drops off to approximately zero. As such, above the third level V_T3, any additional current above the maximum current I_M will only flow through the second set of components 22 and not through the first set of components 20.

It will be appreciated that the maximum current I_M is dependent on the relative resistances of the first and second sets of components 20, 22, and on the difference between the first and second thresholds V_TI , V_T2- AS such, the resistance of the resistor 24 and the value of the second threshold V_T2 are selected based on the forward voltage of the first set of components 20 and the maximum current I_M that is required to flow there through.

Consequently, it will also be appreciated that the configuration of the second set of components 20 (i.e. the number and characteristics of the diodes and their arrangement with respect to one another) may vary significantly because it is selected based on the forward voltage (i.e. V_TI) of the first set of components 20 and the required maximum current I_M.

What is common to all configurations, however, is that the second voltage level V_T2 (i.e. the voltage at which the second set of components begins to conduct current) is higher than the forward voltage of the first set of components 20 (i.e. the first voltage level V_TI) and that, when the voltage is above the second level V_T2, the resistance of the second set of components 22 quickly drops to less than the resistance of the first set of components 20.

In the hypothetical example of Fig. 3, the forward voltage of the LED 10 (i.e. the first threshold V_TI) is approximately 3.2V, the value of the resistor is 5 Ohms, and the second threshold V_T2 provided by the second set of components is approximately 3.5V. This arrangement provides a maximum current I_M of approximately 60mA.

Figs. 4A to 4D show some examples of the way in which the second set of components 20 may be configured so as to achieve desired differences between the first and second voltage levels V_TI , V_T2-

Fig. 4A shows the ideal situation in which the second set of electrical components 22 comprises only a single diode 26 biased in the same direction as the LED 10. The single diode 26 of Fig. 3A must have a forward voltage of higher than the forward voltage of the first set of components 20 by a suitable amount. Sometimes however, this is not possible. As such, as shown in Fig. 4B, the second set of components 22 may instead comprise Zener diode 28 biased in the opposite direction to the LED 10. This may be particularly useful when, for example, the first set of components comprises a single white LED having a forward voltage of 3.2V. Zener diodes are commonly available with reverse voltages of 3.3V and 3.6V, and so a difference between the first and second thresholds V_TI , V_T2 of 0. IV or 0.4V may be achieved. When a Zener diode is reverse-biased, its IV-curve is steeper than the IV-curve of an LED. Consequently, in some examples when the second set of components comprises a reverse-biased Zener diode 28, the resistor 24 from the first set of components may be omitted and yet, if the difference between the first and second voltage levels is set correctly, the IV-curves of the first and second sets of components may still intersect at the third voltage level V_T3. In other examples, the Zener diode 28 may be biased in the same direction as the LED 10.

As will be apparent, it may not always be possible to obtain a suitable difference between the first and second voltage levels V_TI , V_T2 using only a single diode. As such, the second set of components 22 may alternatively comprise a plurality of diodes 26 connected in series. This can be seen in Fig. 4C. The second level V_T2 for this second set of components 22 is simply the aggregate of the forward voltages of each of the diodes 26. If we again consider an example in which the first set of components 20 comprises a single white LED 10 having a forward voltage of 3.2V, the second set of components 22 may be constituted of 5 conventional diodes each having a forward voltage of 0.7V. This would, therefore, provide difference between the first and second levels V_TI , V_T2 of 0.5V. Although in Fig. 3C all the diodes are the same, it will be appreciated that any combination of diodes of different types may be used so as to achieve the required difference in voltage levels. For example, a reverse biased Zener diode having a reverse voltage of 3.3V could be used in combination with a standard diode having a forward voltage of 0.3V to provide a second level of 3.6V.

Fig. 4D shows another alternative arrangement for providing a suitable difference in the levels V_TI , V_T2- In this example, the second set of components 22 comprises a second LED 100A in series with a conventional diode 26A. The LED 100A has the same characteristics as the LED 10 used in the first set of components 20. The conventional diode 26A may have, for example, a forward voltage of 0.3V. This provides a difference of 0.3V. In addition, as shown in Fig. 4D, the LED 100A in the second set of components 22 may also be connected in parallel with a second diode 26B and a third LED 100B connected in series. This limits the amount of current that can flow through the second LED 100A. Although not shown, the third LED 100B may be connected in parallel with a third diode and a fourth LED connected in series, and so on. The arrangement of Fig. 4D, although limiting the amount of current flowing through the LED 10 of the first set of components 20, does not limit the amount of light that is produced by the module 1 as a whole. This is because plural LEDs will be illuminated if the voltage becomes significantly in excess of the second voltage level

Although in some examples the first set of components 20 may not include the resistor 24 in series with the LED 10, the presence of the resistor 24 makes it much easier to set the desired maximum current I_M and provides a more stable and reliable current limitation system. In addition, the range of maximum currents which can be chosen is much greater when the first set of components 20 includes the resistor 24 because it is not determined solely by the inherent properties of the LED 10 and the one or more diodes of the second set of components 22.

In the example of Fig. 2, the module 1 is adapted to receive and transfer electrical energy via inductive coupling with the neighboring modules (not shown). As such, in this example, the first and second electrical energy transfer portions 12A, 12B comprise first and second inductor portions 12 A, 12B. The first and second inductor portions 12 A, 12B may also be referred to as first and second inductance means. The first and second inductor portions comprise first and second inductor coils 12 A, 12B. The first and second inductor coils 12 A, 12B are connected in series with one another. They are wound such that their magnetic fields do not interfere negatively with one another. In the example of Fig. 2, the location of the inductor coils requires that they are wound in the same direction. The current induced in these coils 12A, 12B is necessarily alternating. As such, the module 1 also comprises four diodes 28, which form a rectifier 30 to convert the alternating current into direct current. The module 1 further comprises a capacitor 32 to smooth the direct current produced by the rectifier 30. The smoothed direct current is then routed to the first and second branches 16, 18.

In some examples (not shown in the figures), the first and second inductor portions 12A, 12B may comprise a single inductor coil, which is operable to couple inductively with inductor portions from two neighboring modules. However, the use of two separate inductors allows the coils to be placed at separate locations within the module 1 , which can be beneficial to the propagation of energy between the modules.

Fig. 5 is a schematic circuit diagram of showing a path 33 of four inductively- coupled modules 1 A- ID, along which electrical energy is transferred.

The path 33 is supplied with electrical energy by a power source module 34. The power source module 34 comprises an alternating voltage source 36. The operating frequency of the alternating voltage source 36 may be in the range of, for example, 100 to 1000 KHz. The magnitude of the voltage provided by the alternating voltage source 36 may be in the range of, for example, 5 to 120V. The power source module 34 also comprises a resistor 38. The resistor 38 may have a resistance in the order of 10 milliohms (ιηΩ), but this may depend on the magnitude of the alternating voltage. The power source module 34 also comprises a source inductor coil 40. This may have an inductance of, for example, a few microhenries (μΗ).

The first inductor coil 12A of the first module 1 A is inductively coupled with the source coil 40 of the power source module 34. The inductor coils 12A, 12B of modules 1A-1D in the path 33 each may have an inductance of the order of 100 μΗ. The second inductor coil 12B of the first module 1 A is inductively coupled with the first inductor coil 12A of the second module IB, the second inductor coil 12B of the second module IB is coupled with the first inductor 12A of the third module and so on. As such, electrical energy propagates along the path 33 of modules 1.

Although in Fig. 5 the first inductor coil 12A of one module is coupled with a second inductor coil 12B of another module, this is just for explanatory purposes. In fact, the inductor coils 12 A, 12B of each module are identical and are arranged relative to rectifier 30 such that it does not matter which way round the module is provided in the path 33. In other words, it does not matter which of the inductor coils 12 A, 12B of a module 1 is closer to the source module 36.

Figs. 6 to 8 are graphs depicting currents that flow through the first branch 16 and the second branch 18 (where applicable) of the first three modules 1A-1C in the path 33 over time. The results shown in the graphs were simulated using the following parameters:

the magnitude of voltage provided by the power source 36 = 24V;

- the resistance of the resistor 38 in the source module 34 = 10 ιηΩ;

the inductance of inductor coil 40 in the source module 34 = 2 μΗ;

the inductance of first and second inductor coils 12 A, 12B in the light emitting diode modules 1 = 100 μΗ;

the forward voltage of the LED 10 in the first set of components 20 (i.e. the first voltage level V_Ti) = 3V;

the resistance of the resistor 24 in the first set of components 20 = 5Ω; and the forward voltage of the second set of components 22 (i.e. the second voltage level Vr₂) = 3.5V. Fig. 6 shows the current that flows through the first branches 16 (which include the LEDs 10) of the first, second and third modules 1A-1C in the path 33. In this example, the modules 1A-1C do not include a second branch 18 having the second set of components 22. In other words, the modules 1A-1C include no protection against excessive currents. In this simulation, the coupling constant between the pairs of coupled inductor coils in the path 33 is 0.9. The pairs of coupled inductor coils are the inductor 40 of the source module 34 and the first inductor coil 12A, the second coil 12B of the first module 1 A and the first coil 12A of the second module IB, and the second coil 12B of the second module IB and the first coil 12A of the third module 1C.

As can be seen, the current I16A flowing through the LED 10 of the first module 1 A in the path 33 (i.e. the module closest to the source module 34) is approximately 1.1 A on average. This current I16A is significantly higher that current I16B flowing through the LED 10 of the second module IB, which is approximately 0.62A on average. Similarly, the current I16C flowing through the LED 10 of the third module 1C is significantly lower again and is approximately 0.27A on average.

It can thus be seen from Fig. 6 that wireless coupling of modules 1 so as to illuminate the LEDs 10 provided within the modules 1 is possible without protection against excessive current. However, this not ideal as the LEDs 10 of the modules 1 earlier in the path 33 are exposed to very high currents and so their lifespan may be adversely affected. In addition, there is a significant decrease in the amount of current that reaches each successive module and so paths including a great many modules 1 may not be achievable, without current protection.

Fig. 7 shows the current that flows through first branches 16 of the first second and third modules 1A -1C in the path, when the modules 1 are as described with reference to Fig. 2 and have the electrical characteristics listed above. Fig. 7 also shows the current flowing through the second branches 18 of each of the modules 1A-1C. For this simulation, the coupling constant between the modules is 0.9.

As can be seen from the fact that the graphs of each of currents I_16A, I_I6_B, Ii6c cannot be resolved from one another, very similar, limited currents of approximately, 100mA on average flow through LEDs 10 of each of the first, second and third modules 1A-1C. This limited level of current is such that it may not adversely affect the lifespan of the LEDs 10. The current I_18A, L_SB, L_SC flowing through the second branches 18 of each of the modules gets successively less from the first module 1 A to the third module 1C. As will be appreciated from a comparison of Figs. 7 and 8, the limitation of peak current is particularly useful for the modules 1 most proximate to the power source module 34. However, it is also beneficial in modules at which two paths combine, and the subsequent modules. One such module is marked 46 in Fig. IB and is located at the junction of paths P2 and P3.

Finally, Fig. 8 shows the currents for a similar scenario to that described with reference to Fig. 7. However, in this scenario, the coupling constant between the power source module 34 and first module 1A in the path 33 is only 0.3.

In this scenario, currents I_16A, Ii6B of approximately 100mA flow through the LEDs 10 of the first and second modules 1A, IB, but a reduced current I₁₆c of approximately 70mA flows through the third module 1C. As in Fig. 7, the current flowing through the second branches 18 of the modules 1 reduces from the first to the third module 1A-1C. In fact, as so little energy arrives at the third module 1C, no current at all flows through its second branch 18. This illustrates the importance of good coupling between the power source module 34 and the first module 1 A in the path 33, and indeed between all of the modules 1 in the path 33.

As be understood from the above, it is beneficial for the power source module to be as close as possible to the module at the start of a path, so as to obtain good inductive coupling. This may be achieved by providing the power source module 34 as close as possible to the exterior of a lighting system, such as that shown in Fig. IB. Alternatively, the power source module 34 may be embedded within the lighting system. In this way, a single power source module may power a plurality of different paths. If it is not possible to provide the power source module 34 close to, or within, the lighting system, then the energy provided by the power source module 34 can be increased. Also, more than one power source module 34 may be used to power to a single lighting system.

Fig. 9 is a schematic illustration of an example of the physical structure of the module of Fig. 1. Specifically, the module 1 may comprise a translucent body 42 in which the electronic circuitry (as shown Fig. 2) provided on a circuit board 44 is located. The body 42 may be comprised of a solid material in which the circuit board 44 is embedded.

Alternatively, the body may comprise a hollow shell, with the circuit board 44 provided within the shell. The inductor coils 12A, 12B are provided at opposite sides of the module 1. This is beneficial to the propagation of electrical energy along an extending path of modules 1. Ideally, the inductor coils 12 A, 12B are positioned as close to the exterior of the body 42 as possible. This is beneficial to the formation of strong inductive coupling between inductor coils 12 of neighboring modules 1. The circuit board 44 may be light in color (e.g. white) or may be specularly-reflective. This is beneficial to the transmission of light to the exterior of the module 1. Suitable materials of which the body 42 may be comprised include glass, plastics such as PMMA, PC, PET, PVC, transparent ceramics such as Alumina. The modules may, for example, have a maximum dimension of the order of 10-2m. Differently sized modules may be used to create a single object, with smaller modules being used to create finer (or narrower) features of the object. Although not illustrated in Fig. 9, the components that constitute the second set of components 22 may be provided in a single package.

Although the modules 1 are depicted in Figs. 1 and 9 as spherical, it will be appreciated that other shapes may be used. For example, the modules 1 may be of a shape that has two opposing flat surfaces. The inductor coils 12A, 12B may be provided directly under each of those surfaces. Examples of such shapes include discs and cuboids. Modules 1 shaped in this way may be beneficial to the formation of good inductive coupling between modules 1. This is because the modules 1 may align themselves in planes within the lighting system 3 with flat surfaces (and thus also the inductor coils 12A, 12B) of adjacent modules being adjacent or next to one another.

Although the specific example herein is a wireless LED module 1, it will be appreciated that the electrical circuitry 14 for providing protection for LEDs against high currents may be utilized in any situation in which an LED may be exposed to potentially damaging levels of current. One such situation is LED modules similar to those described with reference to Fig. 2 but which are capacitively-coupled or electrically connected instead of being inductively coupled. Capacitively-coupled modules may include, instead of inductor coils, electrodes provided with a layer of insulating material such that, when two modules in a path are proximate to one another, a polarity may be formed between electrodes of neighboring module across the layers of insulting material. Electrically connected modules may include exposed surface electrodes such that when two modules come into contact electrical charge is able to pass between their surface electrodes. In order to function, capacitively-coupled and electrically connected modules require connection to a power source at either end of the path (instead of requiring a power supply at only one end of the path as is the case with the inductively coupled modules). As such, current protection for those modules at the beginning of a path may not be so beneficial. However, it may still be beneficial for those modules at the junction of two paths (such as module 46 on Fig. IB).

Although in the above-described embodiments the first set of electrical components includes only one light emitting diode, it will be appreciated that the first set of electrical components may include more than one light emitting diode. It will be appreciated that the term "comprising" does not exclude other elements or steps and that the indefinite article "a" or "an" does not exclude a plurality. A single processor may fulfill the functions of several items recited in the claims. 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 an advantage. Any reference signs in the claims should not be construed as limiting the scope of the claims.

Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel features or any novel combinations of features disclosed herein either explicitly or implicitly or any generalization thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the parent invention. The applicants hereby give notice that new claims may be formulated to such features and/or combinations of features during the prosecution of the present application or of any further application derived there from.

Other modifications and variations falling within the scope of the claims hereinafter will be evident to those skilled in the art.

Claims

CLAIMS:

1. A module comprising:

first inductor portion;

second inductor portion; and

at least one light emitting diode,

wherein the first inductor portion, the second inductor portion and the at least one light emitting diode are arranged such that the module is operable to receive electrical energy wirelessly via the first inductor portion from a third inductor portion, to route current through the light emitting diode, and to pass electrical energy wirelessly via the second inductor portion to a fourth inductor portion.

2. The module of claim 1 comprising a first set of electrical components connected in parallel with a second set of electrical components, the wireless receipt of electrical energy via the first inductor portion causing a voltage to be applied across the first and second sets of electrical components,

wherein the first set of electronic components includes the at least one light emitting diode and the second set of electrical components includes at least one diode, wherein the first set of components is configured to conduct current only when a voltage across the first and second sets of electrical components is above a first level,

wherein the second set of components is configured to conduct current only when a voltage across the first and second sets of electrical components is above a second, higher level, and

wherein, when the voltage across the first and second sets of electrical components is at a third level higher than the second level, the resistance of the first set of electrical components is higher than the resistance of the second set of electrical components, such that the current- voltage curve of the second set of components intersects the current-voltage curve of the first set of components when the voltage is at the third level.

3. The module of claim 2, wherein the first set of electrical components comprises a resistor in series with the light emitting diode.

4. The module of claim 2 or claim 3, wherein at least one diode of the second set of components comprises a Zener diode.

5. The module of any of claims 2 to 4, wherein the second set of components comprises a plurality of diodes connected in series.

6. The module of claim 2 or claim 3, wherein the second set of components comprises a light emitting diode and a diode connected in series.

7. The module of any preceding claim wherein the first and second inductor portions are connected to the light emitting diode via a bridge rectifier.

8. The module of any preceding claim further comprising a translucent body, the first and second inductor portions and the light emitting diode being provided within the translucent body.

9. The module of any preceding claim, wherein the first inductor portion comprises a first inductor and wherein the second inductor portion comprises a second inductor, wherein the first and second inductors are provided at opposing sides of the module.

10. Electronic circuitry comprising a first set of electrical components connected in parallel with a second set of electrical components, the first set of electrical components including at least one light emitting diode and a resistor in series and the second set of electrical components including at least one diode,

wherein the first set of electrical components is configured to conduct current only when a voltage across the first and second sets of electrical components is above a first level,

wherein, when the voltage across the first and second sets of electrical components is at a third level higher than the second level, the resistance of the first set of electrical components is higher than the resistance of the second set of electrical components, such that the current- voltage curve of the second set of components intersects the current- voltage curve of the first set of components when the voltage is at the third level.

11. The electronic circuitry of claim 10, wherein at least one diode of the second set of components comprises a Zener diode.

12. The electronic circuitry of claim 10 or claim 11, wherein the second set of components comprises a plurality of diodes connected in series.

13. The electronic circuitry of claim 10 or claim 11 , wherein the second set of components comprises a light emitting diode and a diode connected in series.

14. A module comprising:

the electronic circuitry of any of claims 10 or claim 13; and

first and second electrical energy transfer portions, the first electrical energy transfer portion being operable to receive electrical energy from an electrical energy transfer portion of a first neighboring module and the second electrical energy transfer portion being operable to transfer energy to an electrical energy transfer portion of a second, neighboring module, wherein the first and second electrical energy transfer portions are connected to the electronic circuitry such that receipt of electrical energy via the first electrical energy transfer portion causes a voltage to be applied across the first and second sets of electrical components.

15. A lighting system comprising:

a plurality of modules according to any of claims 2 to 6 and 14; and a translucent portion containing the plurality of modules.