GB2500726A

GB2500726A - Security light

Info

Publication number: GB2500726A
Application number: GB1205838.4A
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: GB201205838D0; GB2500726B

Abstract

A security light has a casing 103 for supporting an array of light emitting diodes, thereby presenting a light emitting surface and aiding removal of heat from them. A transparent cover 106 is attached to the casing to protect the light emitting diodes. The lens cover includes a plurality of lenses 107 moulded therein. Each lens is designed to focus light from a particular location within the array. The divergence of each individual lens is designed to enhance the uniformity of light from the apparatus.

Description

Security Lighting Apparatus

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 security lighting apparatus, of the type having a plurality of light emitting diodes configured to emit light in response to receiving electrical energy.

2. Description of the Related Art

A lighting apparatus that may be configured for use as a security lighting apparatus is disclosed in the applicants co-pending European application 10 251 460 published as 2287524. A lighting apparatus is disclosed in which an array of LED devices are mounted within a casing configured to dissipate heat, such that a significant light energy output may be generated by the apparatus as a whole.

In order to produce a useful beam of light, it is known to direct the light through a focusing lens. When beams from a plurality of sources are combined in this way, a combined light output is produced that will tend to have diverging properties.

In the application of a security light, diverging beams of light can create problems in that the light intensity will vary over an area of interest. Often, in security applications, areas of interest are being viewed by video cameras which wfll tend to automatically adjust themselves so as to produce optimised pictures at the average light intensity. Thus, there is a risk that information will be lost in relatively bright areas and in relatively dark areas. It is therefore desirable in security applications to have a substantially uniform spread of light of similar intensity.

The use of differing lens types in order to control the overall distribution of light is disclosed in US 2010/0097800. published, 22 April 2010. In this publication, individual LED devices are shown each having their own respective housing such that these housings may be combined in an overall apparatus. The provision of an individual housing for each light emitting diode facilitates modifications being made to lens properties. Thus, in this way, it is possible to control the overall distribution of light. However problems occur, firstly in that by the provision of individual housings for each light source, the total energy output of each light source is limited; given that problems wilt be encountered concerning heat dissipation. Furthermore, security lighting apparatus is required to be robust and once installed casual adjustments by operatives should not be encouraged. Thus, a more enclosed unit is often preferred so as not to facilitate adjustment after installation while also ensuring that the heat dissipation properties of the apparatus are maintained.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a security lighting apparatus of the aforesaid type, comprising: a casing for supporting an array of light emitting diodes, thereby presenting a light emitting surface and facilitating the removal of heat from said light emitting diodes; and a substantially transparent cover configured to attach to said casing to protect said light emitting diodes, wherein; said lens cover includes a plurality of lenses moulded therein; each of said lenses is configured to focus light from a particular location within said array; and the divergence for each individual lens is configured to enhance the uniformity of light emitted from the apparatus.

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; Figure 9 shows an alternative view of the apparatus or Figure 1; and Figure 10 shows a schematic representation of lenses.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Figure 1 A light emitting diode (LEO) lighting apparatus is shown in Figure 1 having a plurality 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 26 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 engageabie 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 LEDs 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 light and works in combination with a first video camera 202 and a second video camera 203.

After being attached to walt 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 wall 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 tight 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 rectftying 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 602, 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 fora 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 LEO 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 S 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 moulded around the inclined metallic brackets so as to support these inclined metallic brackets. The casing is moulded from an electrically insulating and thermaUy conductive plastics material. Individually supported light emitting diodes are then located 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 addifion, 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-operathig with a second inclined bracket 802 and an LED assembly 603. 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 LEO 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 LED device to the inner conducting element and from the inner conducting element to a base portion of the second inclined bracket 804. Thus1 from here, similar pathways are repeated throughout the serially connected devices.

Figure 9 The security lighting apparatus illustrated in Figure us shown from an alternative orientation in Figure 9. The plurality of light emitting diodes, configured to emit light in response to receiving electrical energy, are covered by loris cover 106. The casing 103 supports the array of light emithng diodes, thereby presenting a light emitting surface and facilitates the removal of heat from the light emitting diodes.

s The substantially transparent lens cover 106 is configured to attach to the casing 103 to protect the light emitting diodes. The lens cover 106 includes a plurality of lenses, that includes lens 901, lens 902 and lens 903. Each of these lenses 901 to 903 is configured to focus light from a particular location within the LED array. Thus, in the embodiment, each lens aligns with a respective LED die.

The divergence of each individual lens is configured to enhance the uniformity of light emitted from the apparatus. Thus, in this example, the optical characteristics of lens 901 differs from that of lens 902 which in turn differs from that of lens 903.

Figure 10 A schematic representation of lenses 901, 902 and 903 is shown in Figure 10. in this example, lenses towards an edge 1001 of the array have a smaller angle of divergence compared to lenses towards the centre of the array.

In the example, the array is divided into a central group 1002, one or more mid-distance groups 1003 and an outer group 1004. The central group has a first divergence, the mid-distance group or groups have a second divergence greater than said first divergence and the outer group has a third divergence greater than said second divergence.

In an embodiment, the third group 1004 may have a divergence of less than twenty degrees. The second group 1003 may have a divergence of less than forty degrees and the third group 1002 may have a divergence greater than fifty degrees. In a specific example, the first group 1002, including lens 901, has a divergence of sixty degrees, the second group has a divergence thirty degrees and third group has a divergence of ten degrees.

Claims

Claims What we claim is: 1. A security lighting apparatus having a plurality of light emitting diodes configured to emit light in response to receiving electrical energy, comprising: a casing for supporting an array of light emitting diodes, thereby presenting a light emitting surface and facilitating the removal of heat from said light emitting diodes; and a substantially transparent cover configured to attach to said casing to protect said light emitting diodes, wherein: said lens cover includes a plurality of Lenses moulded therein; each of said lenses is configured to focus light from a particular location within said array; and the divergence of each individual lens is configured to enhance the uniformity of light emitted from the apparatus.
2. The apparatus of claim 1, wherein lenses towards an edge of said array have a smaller angle of divergence compared to lenses towards the centre of said array.
3. The apparatus of claim 2, wherein the array is divided into a central group, one or more mid distance groups and an outer group, wherein said central group has a first divergence, said mid distance group or groups has a second divergence greater than said first divergence, and said outer group has a third divergence greater than said second divergence.
4. The apparatus of claim 4, wherein said third group has a divergence of less than twenty degrees, said second group has a divergence of less than forty degrees, and said first group has a divergence greater than fifty degrees.
5. The apparatus of any of claims 1 to 4, wherein 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.
6. The lighting apparatus of claim 5, wherein said light emitting diodes receive rectified pulses of electrical energy.
7. The lighting apparatus of claim 5 or claim 6, wherein said control electronics mounted within said bracket receives an alternating mains supply of electrical energy.
8. The lighting apparatus of any of claims 5 to 7, wherein said casing is moulded from an electrically insulating and thermally conducting plastics material.
9. The lighting apparatus of any of claims 5 to 8, wherein said mounting bracket is moulded from an electrically insulating plastics material.
10. The lighting apparatus of any of claims 5 to 9, wherein each of said plurality of light emitting diodes is held within said casing by a rrietallic assembly.
11. The lighting apparatus of claim 10, wherein said metallic assemblies are connected together electrically to form conducting circuits in series and/or in parallel.
12. The lighting apparatus of any of claims 5 to 11, including push pins for conducting electrical energy from the mounting bracket through the casing.
13. The lighting apparatus of claim 12, when dependant on claim 7, wherein said push pins pass through said casing and electrically connect with said metallic assemblies.
14. The lighting apparatus of any of claims 10 to 13, 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.
15. A method of assembling a security lighting apparatus having a plurality of light emitting diodes configured to emit light in response to receiving electrical energy, comprising the steps of: establishing a casing for supporting an array of light emitting diodes, thereby presenting a light emitting surface and facilitating the removal of heat of light emitting diodes; and attaching a substantially transparent cover over said light emitting diodes that is configured to protect the said light emitting diodes and includes a plurality of lenses moulded therein, wherein: each of said lenses is configured to focus light from a particular location within said array; and the divergence of each individual lens is configured to enhance the uniformfty of light emitted from the apparatus.