Background to the Invention The inventors are aware of conventional low voltage lighting assemblies which require a secondary coil of a transformer to be connected to a power track, the power track including electrical connection means and support means for connecting and supporting a plurality of low voltage light bulbs or lamps to provide lighting to a desired target area. The transformer serves to step down the voltage from a domestic supply voltage of between 110V and 250V AC to a low voltage of between 12V and 24V DC which is useable by such low voltage lighting assemblies.

Typically such low voltage lighting assemblies are configured with the track being located remotely from the transformer. Some such known assemblies have the transformer concealed in a ceiling or wall cavity in the vicinity of the track. All such known systems are typified by the relatively large spatial separation of the track from the transformer.

One reason for the spatial separation of the transformer from the track is the excessive size of the transformer. This excessive size is due, in part, to presently available transformers for low voltage lighting assemblies requiring bulky heat dissipation means. The excessive size is further due, in part, to presently available wire wound transformers for lighting assemblies requiring substantial amounts of copper wire defining primary and secondary coils of the transformers. This precludes the close coupling of transformer to the track.

Furthermore, in conventional lighting assemblies, multiple connection points between the power track and the transformer results in potentially high resistive points where connections are poor. These poor connections result in heat generation at the connection points due to high currents used in low voltage applications. This poses a safety risk and reduces the reliability of the conventional transformer.

Thus known low voltage lighting assemblies are hamstrung by the need for a transformer separate from the power track of the assembly.

Summary of the Invention According to a first aspect of the invention there is provided a lighting assembly which includes a power track to which at least one light source, in use, is attached; and a transformer which includes a magnetic core and a primary coil, wherein the transformer receives the power track so that at least a part of the power track operatively defines at least a part of a secondary coil of the transformer.

The power track typically includes electrical connection means and support means for connecting and supporting the at least one light source.

The power track may include an electrically conductive cable, bar, wire, or the like. The power track may be in the form of an elongate planar member.

The magnetic core may be a planar core. The magnetic core may be a soft ferrite core.

The magnetic core may be shaped and dimensioned to receive the power track. The magnetic core may be shaped and dimensioned so as to receive the power track in a tight fit facilitating coupling of the magnetic core to the power track. The magnetic core may be an E-shaped planar core.

The magnetic core typically has sufficient effective area to allow for minimal secondary windings on the secondary coil, or minimal secondary coils, to achieve a required output voltage. Accordingly, the magnetic core may be defined by at least one pair of planar cores in order to reduce flux density in the core. It is to be appreciated that a single core or several cores may be provided in order to reduce or enhance respectively the flux density.

The primary coil is typically etched onto a substrate. The substrate may be a PC board. The substrate may be multilayered so that the primary coil is etched onto an inner layer of the substrate so as to aid in isolating the primary coil from the secondary coil.

The transformer may be arranged to provide a power output to sufficiently supply a plurality of light sources. The transformer may be arranged to provide a power output of at least 300 W.

The transformer may include a high frequency oscillator for supplying a high frequency voltage required to permit a small dimension magnetic core and primary coil to be used. Typically the high frequency oscillator operates at at least 5 kHz, or even higher depending on design parameters.

The transformer may include output rectification means so as to provide a power output to sufficiently supply a plurality of light sources a long distance away from the transformer while still allowing the transformer to operate at a high frequency.

The transformer may convert a high supply voltage to a low voltage useable by low voltage lighting systems.

The transformer may convert a high supply voltage of between 110V and 250V AC to a low voltage useable by low voltage lighting systems of between about 12V and 24V DC.

The power track may be in the form of a plurality of power tracks so that at least a part of each of the power tracks defines at least a part of a winding of the secondary coil of the transformer or at least a part of one of a plurality of secondary coils of the transformer.

The magnetic core may be shaped and dimensioned to receive at least a part of each of a plurality of power tracks so that at least a part of each of the power tracks defines at least a part of a winding of the secondary coil of the transformer.

The at least one connector of the transformer may be adapted so as to be connectable to the plurality of power tracks.

When the primary coil is etched onto an inner layer of the substrate, the substrate may be connected between a first and a second winding of the secondary coil thereby isolating the first and second windings from each other.

The invention extends to a transformer which includes a primary coil ; and a planar magnetic core associated with the primary coil, which magnetic core is shaped and dimensioned to receive at least a part of a power track therein so that the at least a part of the power track operatively defines at least a part of a secondary coil of the transformer, wherein at least one light source, in use, is attached to the power track.

The magnetic core may be shaped and dimensioned so as to receive the power track in a tight fit facilitating coupling of the magnetic core to the power track. The magnetic core may be an E-shaped planar core.

The magnetic core typically has sufficient effective area to allow for minimal secondary windings on the secondary coil, or minimal secondary coils, to achieve a required output voltage. Accordingly, the magnetic core may be defined by at least one pair of planar cores in order to reduce flux density in

the core. It is to be appreciated that a single core or several cores may be provided in order to reduce or enhance respectively the flux density.

The primary coil is typically etched onto a substrate. The substrate may be a PC board. The substrate may be multilayered so that the primary coil is etched onto an inner layer of the substrate so as to aid in isolating the primary coil from the secondary coil.

The transformer may be arranged to provide a power output to sufficiently supply a plurality of light sources. The transformer may be arranged to provide a power output of at least 300 W.

The transformer may include a high frequency oscillator for supplying a high frequency voltage required to permit a small dimension magnetic core and primary coil to be used. Typically the high frequency oscillator operates at at least 5 kHz, or even higher depending on design parameters.

The transformer may include output rectification means so as to provide a power output to sufficiently supply a plurality of light sources a long distance away from the transformer while still allowing the transformer to operate at a high frequency.

The transformer may convert a high supply voltage to a low voltage useable by low voltage lighting systems.

The transformer may convert a high supply voltage of between 110V and 250V AC to a low voltage useable by low voltage lighting systems of between about 12V and 24V DC.

The power track typically includes electrical connection means and support means for connecting and supporting at least one light source.

The power track may include an electrically conductive cable, bar, wire, or the like. The power track may be in the form of an elongate planar member.

The magnetic core may be shaped and dimensioned to receive at least a part of each of a plurality of power tracks so that at least a part of each of the power tracks defines at least a part of a winding of the secondary coil of the transformer or at least a part of one of a plurality of secondary coils of the transformer.

The at least one connector of the transformer may be adapted so as to be connectable to a plurality of power tracks.

The invention is not limited to the specific embodiments contained in this specification and all variations falling within the spirit of the invention are included in the scope of the invention as if specifically listed.

Description of the Drawings The invention will now be described, by way of illustration only, with reference to the accompanying non-limiting diagrams.

In the drawings, Figure 1 shows, in schematic representation, a low voltage lighting assembly including one power track, in accordance with the invention; Figure 2 shows, in schematic representation, a low voltage lighting assembly including two power tracks stacked atop each other, in accordance with the invention; Figure 3 shows, in schematic representation, a low voltage lighting assembly including two power tracks separated by a substrate which includes a primary coil of a transformer, in accordance with the invention; and

Figures 3a to 3e show, in schematic representation, circuit diagrams of various connection configurations of the low voltage lighting assembly of Figure 3 including output rectification means, in accordance with the invention.

With reference to Figure 1, reference numeral 10 generally indicates a low voltage lighting assembly broadly in accordance with the invention. The lighting assembly 10 includes a power track 12 to which a plurality of low voltage light bulbs or lamps 18 are attached. The lighting assembly 10 further includes a transformer 13 for converting a high voltage supply of between 110V and 250 V AC to a low voltage of between 12V and 24V DC useable by the plurality of low voltage light bulbs or lamps 18.

The transformer 13 includes a magnetic core 16 and a primary coil 28. The magnetic core 16 is coupled to the power track 12 so that the power track 12 defines a secondary coil 14 of the transformer 13. The power track 12 hereby serves to efficiently dissipate heat from the transformer 13.

It is to be appreciated that the even though the term"power track"is preferred when associated with the light bulb or lamp 18 and the term"secondary coil" is preferred when associated with the transformer 13, the power track 12 still defines the secondary coil 14 and the two should not be viewed as being different entities.

The power track 12, in this embodiment of the invention, allows the plurality of light bulbs or lamps 18 to be mounted thereto and to be displaceable there along to provide lighting to a desired target area. The power track 12 is further in the form of an elongate planar substrate which has an electrically conductive path provided therewith in a substantially similar manner to that of a conventional planar transformer.

It is to be understood that in other embodiments of the invention the power track may include an electrically conductive cable, bar, wire, or the like. The power track may then also include electrical connection means and support means for connecting and supporting the plurality of light bulbs or lamps 18.

The transformer 13 optionally includes at least one connector (not shown) for connecting the magnetic core 16 to the power track 12 to facilitate the secondary coil 14 being defined by the power track 12.

The magnetic core 16 is also shaped and dimensioned to receive the power track 12 therein and/or there through so as to facilitate the coupling of the magnetic core 16 to the power track 12. To this end, the magnetic core 16 typically includes an E-shaped planar ferrite core.

In this embodiment of the invention the core 16 is defined by two pairs of E- shaped planar ferrite cores 20,22,24,26 to ensure that the core 16 has sufficient effective area to allow for a single secondary winding on the secondary coil 14 to achieve a required output voltage. Accordingly flux density in the core 16 is reduced. It is to be appreciated that a single core or several cores may be provided in order to reduce or enhance respectively the flux density.

However, it is to be appreciated that any other type of core 16, for example a pot core or the like, may be used.

The primary coil 28 is typically etched onto an inner layer of a substrate 32, typically a conventional PC board, so as to aid in isolating the primary coil 28 from the secondary coil 14 up to very high potentials (5kV and even higher).

The primary coil 28 should not extend to the edges of the substrate 32.

The transformer 13 also includes conventional converter circuitry 30.

The transformer 13 is arranged to provide a power output to sufficiently supply the plurality of light bulbs or lamps 18. The transformer 13 is therefore arranged to provide a power output of at least 300 W.

The transformer 13 includes a high frequency oscillator (not shown) for supplying a high frequency voltage required to permit a small dimension

magnetic core 16 and primary coil 28 to be used. Typically the high frequency oscillator operates at at least 5 kHz, or even higher depending on design parameters.

With particular reference to Figure 2, reference numeral 10. 1 generally indicates a low voltage lighting assembly broadly in accordance with the invention. The assembly 10.1 substantially resembles the assembly 10 and, accordingly, like reference numerals have been used to indicate the same or similar features unless otherwise indicated. The assembly 10. 1 includes a second power track 12.1, in addition to the assembly of Figure 1, so that the first 12 and second 12.1 power tracks define a first 14 and second 14.1 winding of the secondary coil 14,14.1 of the transformer 13. The second power track 12.1 extends in an opposite direction to the first power track 12.

The substrate 32 is stacked atop the first power track 12 which in turn is stacked atop the second power track 12.1 within the core 16.

With particular reference to Figure 3, reference numeral 10.2 generally indicates a low voltage lighting assembly broadly in accordance with the invention. The assembly 10.2 substantially resembles the assembly 10 and, accordingly, like reference numerals have been used to indicate the same or similar features unless otherwise indicated. The assembly 10.2 includes a second power track 12.2, in addition to the assembly of Figure 1, so that the first 12 and second 12.2 power tracks define a first 14 and second 14.2 secondary coil of the transformer 13. The second power track 12.2 extends in the same direction as the first power track 12. The substrate 32 is connected between the first track 12 and the second track 12. 2 thereby isolating the first 14 and second 14.2 secondary coils from each other.

The at least one connector (not shown) of the transformer 13 may in some embodiments of the invention be adapted so as to be connectable to the plurality of power tracks 12,12.1/12,12.2.

Figures 3a to 3e show circuit diagrams of various connection configurations of the low voltage lighting assembly 10.2 of Figure 3 further including output

rectification means. It is to be appreciated that several other rectification configurations are possible and that only some of these are used as example.

It is to be noted that crossing lines only depict an electrical connection where a dot is displayed at the crossing, else the lines merely cross each other without electrical connection.

In these figures cores 20,22,24, and 26 are indicated by a top view of one core 40 only. Core 40 consists of a suitable top and bottom ferrite core assembly. Although not indicated, primary coil 28 is implied to be included in the assembly 10.2 so that only the secondary coil 14,14.2 is illustrated.

In figure 3a the first 14 and second 14.2 secondary coils are connected to each other in parallel and through output rectification means in the form of diodes 41 at one connection point. This provides a power output to sufficiently supply the plurality of tight bulbs or lamps 18 a long distance away from the core 16 while still allowing the transformer 13 to operate at a high frequency. The high operational frequency of the transformer 13 allows the transformer 13 to be small, light and compact.

In Figure 3b the operational direction of the diodes 41 is reversed in order to reverse the polarity of the light bulbs or lamps 18.

In Figure 3c each of the diodes 41 is moved from proximate the connection point to a part of the first 14 and second 14.2 secondary coils, respectively, opposite the core 40 from the light bulbs or lamps 18 in a configuration maintaining the polarity of the light bulbs or lamps 18 of Figure 3b.

It is to be appreciated that diodes 41 can be alternative switching devices such as MOSFETS (Field Effect Transistors). Extra windings may be added to the primary coil 28 to drive the gates of the MOSFETS directly from the core 40. A person skilled in the art would appreciate that the assembly would then be arranged so that the MOSFET gets a turn on voltage as soon as a normal diode 41 in that position would conduct.

It is believed to be an advantage of the lighting assembly that its ability to efficiently dissipate heat from the transformer through the power track, which acts as a heat sink, allows the physical dimensions of the transformer to be reduced and thus facilitates location of the transformer about the power track.

It is therefore not necessary to have a remotely located and concealed bulky conventional transformer which is connected to the power track via relatively thick connection leads.

Furthermore, it is also believed to be an advantage that as the power track forms an integral part of the transformer, the number of connection points where heat can be generated are reduced.