GB2550128A

GB2550128A - Lighting unit

Info

Publication number: GB2550128A
Application number: GB1608020.2A
Authority: GB
Inventors: Desmond John
Original assignee: JCC Lighting Products Ltd
Current assignee: JCC Lighting Products Ltd
Priority date: 2016-05-09
Filing date: 2016-05-09
Publication date: 2017-11-15
Also published as: GB201608020D0

Abstract

A lighting unit 1 comprises a main part 2 having a housing 21 and a heat sink (24, figure 2B), the heat sink being fixed at least partially within the housing and having a heat transfer surface accessible through a main opening in the housing. The lighting unit also comprises a removable LED module 3 for generating light, the LED module having a heat transfer surface 31 for transferring heat to the heat sink via the heat transfer surface of the heat sink. When the removable LED module is mounted to the main part, the heat transfer surfaces of the heat sink and the LED module are adjacent. In this way, replacement of only the LED module is possible, while leaving the main part of the light in place. This is particularly useful in the case of a ceiling recessed downlight, in which the replacement of the entire unit is inconvenient and may cause damage to the ceiling. Further, replacing the LED module only can be expected to be less expensive than replacing the entire lighting unit.

Description

Lighting Unit

Technical Field

The present invention relates to a lighting unit.

Background

Some lighting units, for example downlights, are formed of a housing, an LED module and lens, and a heat sink fixed to the back of the LED module to dissipate heat. If the LED module fails, or if a user wishes to use a light source which is more or less powerful, or uses a different colour temperature, a different lens with a different aesthetic effect, or to upgrade the LED module technology, then the entire lighting unit must be replaced.

Summary of the Invention

According to the present invention, there is provided a lighting unit, comprising: a main part comprising a housing and a heat sink, the heat sink being fixed at least partially within the housing and having a heat transfer surface accessible through a main opening in the housing; and a removable LED module for generating light, the LED module having a heat transfer surface for transferring heat to the heat sink via the heat transfer surface of the heat sink; wherein, when the removable LED module is mounted to the main part, the heat transfer surfaces of the heat sink and the LED module are adjacent.

In this way, the present technique permits replacement of only the LED module, while leaving the main part of the light in place. This is particularly useful in the case of a ceiling recessed downlight, in which the replacement of the entire unit is inconvenient and may cause damage to the ceiling or the fitting. Further, replacing the LED module only can be expected to be less expensive than replacing the entire lighting unit. The use of the heat transfer surfaces addresses the problem of having to replace the entire lighting unit when the LED module fails or needs to be replaced, as in conventional lighting units the heat sink is directly bonded to the LED module.

Preferably, the heat transfer surfaces of the heat sink and the LED module are complementary in shape, in order to substantially maximise the contact area between the heat transfer surfaces to improve heat transfer. More preferably, the heat transfer surfaces of the heat sink and the LED module are substantially planar.

It will be understood that the heat sink may be fixed entirely within the housing.

Preferably, the lighting unit comprises a deformable heat transfer element for substantially bridging a gap between the heat transfer surfaces of the heat sink and the LED module. The deformable heat transfer element can be mounted between the two heat transfer surfaces to effectively fill an air gap between the heat transfer surfaces of the heat sink and the LED module. Without this, there could be an imperfection in the shape of the heat transfer surfaces, or it would allow a foreign body to be present between the heat transfer surfaces, resulting in an air gap between the heat transfer surfaces which would reduce heat transfer efficiency. The deformable heat transfer element may have at least one adhesive surface, enabling it to be adhered to one (or both) of the heat transfer surfaces. Alternatively, the deformable heat transfer element may be permanently attached to the removable LED module.

The lighting unit may comprise one or more engagement formations on one of the removable LED module and the main part, and one or more receiving structures on the other of the removable LED module and the main part, the engagement formations and receiving structures being engageable with each other to mount the LED module to the main part of the lighting unit. The receiving structures may each comprise a slot having a first portion into which and from which the engagement formations can be inserted and retracted, and a second portion from which the engagement formations cannot be retracted, and wherein the removable LED module is engageable with the main part by inserting the engagement formations into the first portion of the engagement slots and rotating the LED module with respect to the main part to engage the engagement formations with the second portion of the engagement slots. Preferably, an electrical connection between the main part of the lighting unit and the LED module is provided via the engagement formations. In this case it will be appreciated that at least two engagement formations should be provided in order to provide a complete electrical circuit. Advantageously, this means that mechanical engagement of the LED module with the main part of the lighting unit results in the electrical connection occurring, and also reduces the number of parts (since the same parts perform two functions in this case). In one embodiment, the engagement formations are provided on the LED module, the receiving structures are provided on the main part, and the main part comprises an electrical contact plate accessible to the engagement formations via the receiving structures. Since the electrical contact of the main part (electrical contact plate) is concealed behind the receiving structures, safety is improved, since a user’s fingers (or a screwdriver) cannot, or are less likely to, accidentally touch the electrical contact. However, the appropriately dimensioned engagement formations are able to access the contact plate via the receiving structures.

The LED module may comprise a lens for guiding the light generated by the LED module into a desired light output distribution.

The lighting unit may further comprise a removable bezel which is removably engageable with the main part or the LED module. In this way, the lighting unit can be customised in terms of light output and/or colour (by replacing the LED module) and exterior appearance (for example shape and/or colour) by replacing the bezel.

Preferably, an electrical power supply path to the removable LED module extends through or alongside the heat sink within the housing. Advantageously, this means that a power cable or wires do not need to extend down the outside of the lighting module, and that electrical connections to a power supply can be made at a top portion of the lighting module.

While in the present embodiment the lighting unit is a downlight, the technique is also applicable to other types of lighting unit, such as but not limited to a spotlight.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings where like parts are provided with corresponding reference numerals and in which:

Figures 1A and 1B schematically illustrate a lighting unit;

Figures 2A and 2B schematically illustrate a main part of the lighting unit, including a cross section through the main part;

Figures 3A and 3B schematically illustrate a removable LED module of the lighting unit, including a cross section through the LED module; and Figures 4A and 4B schematically illustrate how the LED module and the main part are mechanically and electrically connected to each other.

Detailed Description

Referring to Figures 1A and 1B, which respectively show a lighting unit 1 (in this example a downlight) from two different views, the lighting unit 1 can be seen to comprise a main part 2, a removable LED module 3 and a bezel 4. The LED module 3 generates light and focuses it externally of the lighting unit 1. The bezel provides an attractive finish when the lighting unit 1, which may be installed in a ceiling, is viewed from below, and provides an opening through which light generated by the LED module 3 can pass. The bezel 4 is removably engageable with either the main part 2 directly or with the LED module 3. The main part 2 comprises a housing 21, or can, having at one end a cable which extends to an electrical connector 22 for connection to an electricity circuit, and at the other end an opening 23 for receiving the LED module 3. Within the housing 21 is provided a heat sink 24 (not visible in Figures 1A and 1B, but visible in the cross sectional view of Figure 2B which will be described below), being fixed within the housing and having a heat transfer surface 25 accessible through the opening 23. The heat transfer surface 25 can be seen to be proximate to and exposed through the opening 23. The LED module 3 itself comprises a heat transfer surface 31, which when the removable LED module 3 is mounted to the main part 2, is adjacent to the heat transfer surface of the heat sink.

As a result, heat generated by the LED module 3 is transferred to the heat sink via the heat transfer surfaces 25 and 31, to be dissipated. It can be seen from Figures 1A and 1B that the heat transfer surfaces 25, 31 of the heat sink and the LED module 3 are substantially complementary in shape, and in particular are substantially planar.

It can be seen that the LED module 3 comprises engagement formations 32, or protrusions, each having a relatively narrow stem and a relatively wide head. The main part 2 comprises receiving structures 26, in the form of a slot having a first (wide) portion into which and from which the engagement formations 32 can be inserted and retracted, and a second (narrow) portion from which the engagement formations 32 cannot be retracted. In other words, the wide portion of the slot of the receiving structures 26 permits entry and exit of the head of an engagement formation 32 while the narrow portion permits the neck of the formation to travel along the slot of the receiving structure 26 while trapping the head of the engagement formation 32. As a result, the removable LED module 3 is engageable with the main part 2 by inserting the engagement formations 32 into the first portion of the slots of the receiving structures 26 and rotating the LED module 3 with respect to the main part 2 to engage the engagement formations 32 with the second portion of the slots of the receiving structures 26. It will be appreciated that while only one of the receiving structures 26 is visible in Figure 1B, a receiving structure will be provided to correspond to each engagement formation 32 of the LED module 3. It will also be appreciated, that while in the present embodiment the engagement formations 32 are provided on the LED module 3 and the receiving structures 26 are provided on the main part 2, it is equally possible to provide an alternative embodiment in which engagement formations 32 are provided on the main part 2 and the receiving structures 26 are provided on the LED module 3. Alternatively, each of the main part 2 and the LED module 3 could be provided with at least one engagement formation 32 and at least one receiving structure 26. In any case, it will be understood that the engagement formations 32 and receiving structures 26 are engageable with each other to mount the LED module 3 to the main part 2 of the lighting unit 1.

Referring to Figure 2A, a side view of the main part 2 of the lighting unit 1 is shown. Figure 2B shows a cross section through the main part 2, along the line A-A marked on Figure 2A. In Figure 2B, the heat sink 24 is shown, and occupies much of the interior space of the main part 2. The heat sink 24 is of a size and type suitable for the most powerful LED module 3 which the lighting unit 1 is intended to utilise. It will be understood that generally LED modules are matched with a heat sink which is suitable for the amount of heat expected to be generated by that particular LED module, but that in the present case the separation of the heat sink and the LED module makes it necessary, or at least desirable, to provide the lighting unit 1 with a heat sink 24 which is suitable for all expected LED modules 3. Also visible in Figure 2B is the receiving part 26 for receiving the engagement formations 32 (shown in Figure 1B). An electrical contact plate 28 is provided within the main part 2, and is accessible to the engagement formations 32 via the receiving structures 26, as will be described further below in relation to Figures 4A and 4B.

Referring to Figure 3A, a side view of the LED module 3 of the lighting unit 1 is shown. The engagement formations 32 are visible in Figure 3A, projecting from the upper surface of the LED module 3. Figure 3B shows a cross section through the LED module 3, along the line B-B marked on Figure 3A. In Figure 3B, the LED module 3 can be seen to comprise a lens 33, a circuit board 34 bearing one or more LEDs and an LED driver, and a thermal pad 35 for improving heat transfer between the heat transfer surfaces 25, 31 (shown in Figures 1A and 1B). In particular, the thermal pad 35 forms a deformable heat transfer element which is mounted between the heat transfer surface 25 of the heat sink 24 and the heat transfer surface 31 of the LED module 3 when the lighting unit 1 is assembled. The thermal pad 35 has an adhesive surface, thereby permanently attaching it to the heat transfer surface 31 of the removable LED module 3. In the present embodiment no adhesive is used between the thermal pad 35 and the heat transfer surface 25, with contact in this case being achieved by way of the deformable nature of the thermal pad 35 and the mechanical engagement between the main part 2 and the LED module 3. The heat transfer pad may be of any suitable material (or combination of materials) providing suitable deformation and heat transfer properties. Such heat transfer pads are known in the art, and are commonly formed of paraffin wax or silicon based materials. When the main part 2 and the LED module 3 are assembled together, the thermal pad 35 is sandwiched between the heat transfer surfaces 25, 31 to provide an efficient heat transfer path from the LED module 3 to the heat sink 24.

Referring to Figures 4A and 4B, cut-through representations are provided of the main part 2 showing the receiving structures 26, and the engagement formations 32 located within the receiving structures 26. Electrical conductors 51 are shown, which extend through or alongside the heat sink 24 to the contact plate 28 shown in Figure 2B. An electrical connection between the main part 2 and the LED module 3 is provided via the engagement formations 32. In particular, the engagement formations 32 are electrically connected to the circuit board 34 (and in particular to the LED driver), and are brought into contact with the contact plate 28 when located within the receiving structures 26 as shown in Figure 4B. An electrical path is then provided from the LED driver to the lighting circuit via the engagement formations 32, the contact plate 28, the conductors 51 and the connector 22.

Claims

1. A lighting unit, comprising: a main part comprising a housing and a heat sink, the heat sink being fixed at least partially within the housing and having a heat transfer surface accessible through a main opening in the housing; a removable LED module for generating light, the LED module having a heat transfer surface for transferring heat to the heat sink via the heat transfer surface of the heat sink; wherein, when the removable LED module is mounted to the main part, the heat transfer surfaces of the heat sink and the LED module are adjacent.

2. A lighting unit according to claim 1, wherein the heat transfer surfaces of the heat sink and the LED module are complementary in shape.

3. A lighting unit according to claim 2, wherein the heat transfer surfaces of the heat sink and the LED module are substantially planar.

4. A lighting unit according to any preceding claim, comprising a deformable heat transfer element for substantially bridging a gap between the heat transfer surfaces of the heat sink and the LED module.

5. A lighting unit according to claim 4, wherein the deformable heat transfer element has at least one adhesive surface.

6. A lighting unit according to claim 4, wherein the deformable heat transfer element is permanently attached to the removable LED module.

7. A lighting unit according to any preceding claim, comprising one or more engagement formations on one of the removable LED module and the main part, and one or more receiving structures on the other of the removable LED module and the main part, the engagement formations and receiving structures being engageable with each other to mount the LED module to the main part of the lighting unit.

8. A lighting unit according to claim 7, wherein the receiving structures each comprise a slot having a first portion into which and from which the engagement formations can be inserted and retracted, and a second portion from which the engagement formations cannot be retracted, and wherein the removable LED module is engageable with the main part by inserting the engagement formations into the first portion of the engagement slots and rotating the LED module with respect to the main part to engage the engagement formations with the second portion of the engagement slots.

9. A lighting unit according to claim 8, wherein an electrical connection between the main part of the lighting unit and the LED module is provided via the engagement formations.

10. A lighting unit according to claim 9, wherein the engagement formations are provided on the LED module, the receiving structures are provided on the main part, and the main part comprises an electrical contact plate accessible to the engagement formations via the receiving structures.

11 .A lighting unit according to any preceding claim, wherein the LED module comprises a lens.

12. A lighting unit according to any preceding claim, comprising a removable bezel which is removably engageable with the main part or the LED module.

13. A lighting unit according to any preceding claim, wherein an electrical power supply path to the removable LED module extends through or alongside the heat sink within the housing.

14. A lighting unit according to any preceding claim, wherein the lighting unit is a downlight.

15. A lighting unit substantially as hereinbefore described with reference to the accompanying drawings.