GB2500727A

GB2500727A - Lighting apparatus

Info

Publication number: GB2500727A
Application number: GB1205841.8A
Authority: GB
Inventors: Shane Vincent Lee Newman
Original assignee: Graviton Lite Ltd
Current assignee: Graviton Lite Ltd
Priority date: 2012-03-31
Filing date: 2012-03-31
Publication date: 2013-10-02
Anticipated expiration: 2032-03-31
Also published as: GB2500727B; GB201205841D0

Abstract

A lighting apparatus has a plurality of light emitting diodes. A mounting bracket 102 is substantially permanently attachment to a structural element. A casing 103 supports the light emitting diodes and aids the removal of heat from them. The casing 103 is detachably mounted on the mounting bracket 102. Electronics for controlling the supply of electrical energy to the light emitting diodes is contained within the mounting bracket 102.

Description

I

Lighting Apparatus and a Method of Lighting

CROSS REFERENCE TO RELATED APPLICATIONS

This application represents the first application for a patent directed towards the invention and the subject matter.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lighting apparatus having a plurality of light emitting diodes.

2. Description of the Related Art

A lighting apparatus having a plurality of light emitting diodes is disclosed in the applicants co-pending European patent application 10 251 460 (published as 2 287 524). In this publication, a casing is disclosed that is moulded from an electrically isolating and thermally conductive plastics material. The casing contains a plurality of metallic assemblies, wherein each one of these metallic assemblies provides electrical power to a respective one of the LED devices.

An advantage of the known lighting apparatus is that it facilitates modification in terms of the type of light required. Thus, by providing sub-assemblies that may be exchanged for alternative LED types, it is possible to change the characteristics of the lighting produced.

A problem with this approach is that a change in lighting type often requires all of the LEDs to be replaced. Thus, it may be preferable to replace the casing as a whole. However, when making changes of this type, current systems require the whole of the unit to be replaced.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a lighting apparatus having a plurality of light emitting diodes configured to emit light in response to receiving electrical energy? comprising: a mounting bracket arranged to be a substantially permanent attachment to a structural element; and a casing for supporting said light emifting diodes and for facilitating the removal of heat from said light emitting diodes, characterised in that; said casing is detachably engagable upon said mounting bracket; and control electronics for controlling the supply of said electrical energy to said light emitting diodes is contained within said mounting bracket.

In an embodiment, the light emitting diodes receive rectified pulses of electrical energy. Furthermore, in an embodiment, the control electronics mounted within the bracket receives an alternating mains supply of electrical energy. In an embodiment, an LED wafer or die is mounted on an inner conductive element, a coaxial separating element is provided that is electricaily insulating and thermally conductive and said coaxial separating element is surrounded by a coaxial outer conducting element.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a light emitting diode (LED) lighting apparatus; Figure 2 illustrates the installation of the apparatus shown in Figure 1; Figure 3 further details the installation of the apparatus shown in Figure 1; Figure 4 shows a schematic representation of the lighting apparatus; Figure 5 shows a plurality of metallic assemblies; Figure 6 shows the establishment of the assemblies identified in Figure 5; Figure 7 shows an LED sub-assembly; and Figure 8 illustrates the supply of electrical power to the LED devices using the assemblies of Figure 5.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Figurel A light emitting diode (LED) lighting apparatus is shown in Figure 1 having a pluraflty of light emitting diodes configured to emit light, in response to receiving electrically energy, in the direction of arrow 101. A mounting bracket 102 is arranged to be a substantially permanent attachment to a structural element, such as a wall, as illustrated in Figure 2. A casing 103 supports the light emitting diodes and facilitates the removal of heat from these light emitting diodes. Thus, the outer surface of the casing 103 effectively presents a heat sink thereby dissipating heat to atmosphere.

The casing 103 is detachably engageable upon the mounting bracket 102. Furthermore, control electronics for controlling the supply of electrical energy to the light emitting diodes is contained within the mounting bracket 102. Thus, the drive electronics are in a separate unit so that they are external to the heat sink housing. In this way, heat form the drive electronics is not added to the heat generated by the light emitting diodes, thereby enhancing the capability of the casing 103 to remove heat generated by the [EQs and facilitating efficient operation.

In an embodiment, the casing 103 is moulded from an electrically insulating but thermally conducting plastics material. In an embodiment, the mounting bracket 102 may be constructed from similar material. However, in an alternative embodiment, the mounting bracket is moulded from an electrically insulating plastic material but with less of a requirement to conduct heat. In this way, material costs for the bracket 102 may be reduced.

The thermally conductive casing 103 may be constructed from an E2 thermally conductive liquid crystalline polymer, thermally conductive polyamide or a thermally conductive polycarbonate.

In an embodiment, the mounting bracket 102 includes a first push pin 104 and a second push pin 105 for conducting electrical energy from the mounting bracket through the casing 103. In an embodiment, the push pins pass through the casing and may electrically connect with metallic assemblies contained within the casing.

Figure 2 Installation of the apparatus identified in Figure 1 is detailed in Figure 2.

Mounting bracket 102 is secured to a wall 201 in the example, as shown in Figure 2. In this example, the lighting apparatus is being used as a security is light and works in combination with a first video camera 202 and a second video camera 203.

After being attached to wall 201, the mounting bracket 102 is connected to an electricity supply. In an embodiment, the bracket is connected to an alternating mains supply such that the control electronics mounted within the bracket receives an alternating mains supply of electrical energy. In alternative configurations, rectified energy may be supplied to the bracket 102.

Figure 3 After securing the mounting bracket 102 to the waIl 201, the casing 103 is detachably engaged upon the mounting bracket 102. Thus, when attached, the casing 103 is held firmly in place to the mounting bracket 102.

Furthermore, a connection takes place, via pins 104 and 105, so as to supply controlled electrical energy through the casing and to the assemblies upon which the LED devices are attached. In an embodiment, the light emitting diodes receive rectified pulses of electrical energy.

Figure 4 A schematic representation of the lighting apparatus is shown in Figure 4. The mounting bracket 102 is arranged to be a substantially permanent attachment to a structural element and the casing 103 supports the light emitting diodes 401 to 418. The casing 103 is detachably engagable upon the mounting bracket 102. Control electronics for controlling the supply of electrical energy to the light emitting diodes is contained within the mounting bracket 102.

Within the mounting bracket 102, in this embodiment, a mains supply is received by a transforming and rectifying circuit 419. Rectifying circuit 419 supplies power to a communication circuit 420 and a power output circuit 421.

The communication circuit 420 facilitates data communication with external devices via an output port 422. The power output circuit 421 supplies output power to a first output socket 423 and a second output socket 424.

After the casing 103 has engaged with mounting bracket 102, a push pin 425 engages within socket 423 and a push pin 426 engages within socket 424.

Light emitting diodes 401 to 418 receive rectified pulses of electrical energy, wherein the power supplied to the LED devices may be controlled by a process of pulse width modulation. In an alternative embodiment, direct current is supplied to the casing 103 via pins 425, 426 with the voltage of the supply being controlled.

In the embodiment, a substantially rectangular array of LED devices 401 to 418 is held within the casing 103 by means of metallic assemblies. In this example, a first group of LED devices 401 to 406 are connected in series, a second group of devices 407 to 412 are connected in series and a third group of devices 413 to 418 are connected in series. These three groups are then connected in parallel.

Figure 5 A plurality of metallic assemblies are illustrated in Figure 5, each one providing electrical power to a respective one of the LED devices. In addition, these metallic assemblies conduct heat away from their respective LED device such that this heat may be dissipated to atmosphere through the thermally conductive casing 401.

The plurality of metallic assemblies shown in Figure 5 define a matrix of three groups, with six assemblies within each group. Thus, there are a total of eighteen LED dies 501 within the lighting apparatus. However, it should be appreciated that many alternative configurations could be deployed.

From an electrical perspective, the six assemblies within each group, including group 502, are connected in series and then each group is electrically connected in parallel. Group 502 includes a first assembly 503, a second assembly 504, a third assembly 505, a fourth assembly 506, a fifth assembly 507 and a sixth assembly 508. This configuration is then repeated for a second group 509 and a third group 510.

Figure 6 It can be seen from Figure 6 that the individual metallic assemblies are arranged such as to define a regular matrix of light emitting diode devices, Each of the metallic assemblies includes an inclined bracket 601 having a base portion 602, an inclined portion 603 and a raised portion 604. The raised portion supports an LED subassembly 605.

Within the matrix, a first attached inclined bracket 508 is next to a second inclined bracket 509. The raised portion 604 of the second inclined bracket 509 is above the base portion 602 of the first inclined bracket 508. In this configuration, the base portion 602 of the first inclined bracket 508 lies between the raised portion 604 of the second inclined bracket 509 and the moulded casing.

The base portion 602 includes a lower threaded hole 606. The raised portion 604 includes an upper non-threaded hole 607.

Figure 7 An LED subassembly 605 is detailed in Figure 7. The LED subassembly 605 includes an inner conductive element 701 which has an LED die 702 mounted thereon to provide thermal conduction of heat away from the LED die, thereby allowing the LED die to operate at higher power ratings. In addition, a first electrical connection 703 is made between the LED wafer 702 and the inner electrically conductive element 701.

The LED subassembly 605 also includes a coaxial insulating element 704 that may be constructed from substantially similar material to that of the moulded casing. Thus, the coaxial insulating element 704 is electrically insulating while being thermally conductive.

The LED subassembly 605 also includes a coaxial outer conductive element 705 electrically insulated from the inner conductive element 701.

Furthermore, an electrical connection 706 is made between the LED die 702 and the coaxial outer conductive element 705.

The coaxial insulating element 704 extends below the coaxial outer conductive element. The coaxial outer conductive element 704 is received within an upper hole 607 of an aligned pair and may be held firmly within this upper hole by the provision of an interference fit.

The inner conductive element 701 extends below the coaxial insulating element 704 and includes a threaded portion 707. Threaded portion 707 engages with tapped hole 606 so as to secure each LED subassembly within the matrix of inclined brackets.

During the fabrication of the apparatus the inclined metallic brackets shown in Figure 5 are arranged within a mould. A casing, as shown in Figure 1, is rnoulded around the inclined metallic brackets so as to support these inclined metallic brackets. The casing is moulded from an electrically insulating and thermally conductive plastics material. Individually supported light emitting diodes are then iocatecl within each of a respective one of the inclined metallic brackets. Thus, the close proximity of the LED device to the relatively large metallic components which are then in turn brought into close proximity with a thermally conductive plastic casing facilitates the dissipation of heat from the LED devices. In addition, this facilitates the replacement of individual LED devices, which in turn facilitates the use of the apparatus in situations requiring different light wavelengths.

Figure 8 Figure 8 illustrates how electrical power is supplied to each of the plurality of light emitting diode devices contained within the lighting apparatus.

As shown in Figure 5, a plurality of inclined metallic brackets are arranged in a matrix and for the purposes of this illustration, a first inclined bracket 801 is shown co-operating with a second inclined bracket 802 and an LED assembly 803. As previously described, each inclined metallic bracket includes a base portion 602. an inclined portion 603 and a raised portion 604. The base portion 602 includes a tapped lower hole 606 and the raised portion 604 includes an upper hole 607 that has a larger diameter than the lower hole.

A casing 103 is moulded around the inclined metallic brackets which then defines one or more groups. Thus, in this embodiment, three groups 502, 509 and 510 are established. Within each group, the brackets are serially connected, such that power is applied across the ends of each group and a plurality of groups are connected in parallel.

When held within the moulded casing, the lower hole 606 of the first bracket 801 is located directly below the upper hole 607 of the second bracket 802, thereby defining a matrix of aligned holes.

In production, the moulded casing is removed from its mould and, when so removed, the casing supports the brackets thereby electrically isolating them but providing thermal conductivity so as to dissipate heat generated by the LED devices. The moulded casing thereby provides a mechanical support for the devices and a heat sink for the devices.

LED subassemblies 803 are inserted through respective aligned holes, with each of the LED subassemblies including an inner conductive element 701, a coaxial insulating element 704 and a coaxial outer conductive element 705. An LED wafer 702 is mechanically and electrically connected to the inner conductive element 701 to facilitate electrical transmission and heat transmission. As previously described, an electrical connection is also made between the outer conductive element 705 and the LED die 702.

An electrical path is provided between a first end 806 of the group and a second end 807 of the group. Thus, starting from the first end 806, a current path is provided along inclined bracket 802 which is in mechanical contact with the outer conducting element 705 and the coaxial insulating element 704. In this embodiment, a secure mechanical interference fit is provided between the insulating element 704 and the outer conductor 705 but the presence of the insulating element 704 presents a direct electrical path between inclined bracket 802 and the inner conductor 701 Electrical transmission to the inner conductor 701 is provided through the LED device. Thus, an electrical path is provided from a raised portion of a first inclined bracket 802 to an outer conducting element, through the LEO device to the inner conducting element and from the inner conducting element to a base portion of the second inclined bracket 804. Thus, from here, similar pathways are repeated throughout the serially connected devices.

Claims

Claims What we claim is: 1. A lighting apparatus having a plurality of light emitting diodes configured to emit light in response to receiving electrical energy, comprising: a mounting bracket arranged to be a substantially permanent attachment to a structural element; and a casing for supporting said light emitting diodes and for facilitating the removal of heat from said light emitting diodes, characterised in that: said casing is detachably engagable upon said mounting bracket; and control electronics for controlling the supply of said electrical energy to said light emitting diodes is contained within said mounting bracket.
2. The lighting apparatus of claim 1, wherein said light emitting diodes receive rectified pulses of electrical energy.
3. The lighting apparatus of claim I or claim 2, wherein said control electronics mounted within said bracket receives an alternating mains supply of electrical energy.
4. The lighting apparatus of any of claims 1 to 3, wherein said casing is moulded from an electrically insulating and thermally conducting plastics material.
5. The lighting apparatus of any of claims 1 to 4, wherein said mounting bracket is moulded from an electrically insulating plastics material.
6. The hghting apparatus of any of claims 1 to 5, wherein each of said plurality of light emitting diodes is held within said casing by a metallic assembly
7. The lighting apparatus of claim 6, wherein said metallic assemblies are connected together electrically to form conducting circuits in series and/or in paralleL
8. The lighting apparatus of any of claims 1 to 7, including push pins for conducting electrical energy from the mounting bracket through the casing.
9. The lighting apparatus of claim 8, when deperidant on claim 7, wherein said push pins pass through said casing and electrically connect with said metallic assemblies.
10. The lighting apparatus of any of claims 6 to 9, wherein each said assembly includes: an inner conductive element with an LED die mounted thereon; a coaxial separating element that is electrically insulating and thermally conductive; and a coaxial outer conducting element.
11. A method of attaching a lighting apparatus to a structural element, comprising the steps of providing a substantially permanent attachment of a mounting bracket to said structural element; and detachably engaging a casing to said mounting bracket, wherein; control electronics for controlling a supply of electrical energy to said light emitting diodes is contained within said mounting bracket; and said casing supports said light emitting diodes and facilitates the removal of heat from said light emitting diodes.
12. The method of claim 11 further comprising the step of supplying alternating mains electricity to said bracket.
13. The method of claim 11 or claim 12, further comprising the step of moulding said casing from an electrically insulating and thermally conducting plastics material.
14. The method of any of claims 11 to 13, further comprising the steps of locating light emitting diodes within rnetaflic assemblies constrained within said casing.
15. The method of any of claims 11 to 14, further comprising the step of applying an LED die to an inner conductive element; applying a coaxial separating element that is electrically insulating and thermally conductive; and applying a coaxial outer conducting element.