WO2019020754A1

WO2019020754A1 - Fool proof connector for multiple pcb thickness

Info

Publication number: WO2019020754A1
Application number: PCT/EP2018/070306
Authority: WO
Inventors: Charles Leonardus Cornelius Maria KNIBBELER; Peter Hubertus Franciscus Deurenberg; Antonius Adrianus Maria Marinus; Martinus Petrus Creusen
Original assignee: Philips Lighting Holding B.V.
Priority date: 2017-07-28
Filing date: 2018-07-26
Publication date: 2019-01-31

Abstract

A connector for connecting a PCB to an electrical circuit. The connector configured to accommodate varying PCB thicknesses whilst maintaining a similar contact pressure on the contact areas of the PCB and simultaneously ensuring good thermal contact between the PCB and a luminaire base.

Description

FOOL PROOF CONNECTOR FOR MULTIPLE PCB THICKNESS

TECHNICAL FIELD

The present disclosure relates to a connector that can accommodate varying thicknesses of PCB. BACKGROUND

Luminaires have been making a transition from conventional light source technologies such as compact fluorescent lamps (CFL), tubular lamps (TL) and incandescent light bulbs towards light emitting diode (LED) light sources. One of the main reasons for the technology shift was the promise of much more efficient light sources, another benefit of the LED technology was a much smaller form factor of the individual light sources. One of the major challenges to the successful adoption of the LED as a viable alternative was the question of heat management and its positive effect on LED lifetime when correctly resolved. A well accepted practice is to provide an LED with a heatsink to transport the heat away from the LED junction and dissipate it in the surrounding environment. The heatsink may be attached to an individual LED but more commonly multiple LEDs are located on a printed circuit board (PCB) which is then attached to the heatsink. In some instances, the heatsink may be external to the luminaire whilst in other cases the body of the luminaire acts as the heatsink.

Modern manufacturing techniques often mean that a company may outsource production of certain components to external companies and these components must be integrated into the finished product. There is a disadvantage when integrating components into larger components or into finished products, the manufacturing process may lead to a variation in the physical dimensions of the sourced components especially if the components are outsourced from more than one company.

Therefore, a desire exists for an improved integration between componentry of varying physical dimensions. SUMMARY

In a first aspect, according to claim 1, a luminaire comprising a connector for connecting a PCB to an electrical circuit is provided. The connector comprises a body, an opening for receiving the PCB, and contacts for providing an electrical connection between a power source and the PCB. The body of the connector having mechanical registers located within the opening. The luminaire further comprises a planar heatsink and the connector is movable along a translational axis that is perpendicular to the plane of the heatsink. This movement allows the connector to reach a heat sinking position wherein the PCB, when received by the opening, is in thermal contact with the planar heatsink.

In one embodiment, the connector is configured to accept PCBs of varying thickness. This varying thickness may be in the range of 0.8mm to 2mm. Such a variation leads to difficulties in ensuring that contact is made in a way that does not exert too much pressure on the PCB but equally that ensures that sufficient pressure is applied so that an acceptable contact is made. A range of connectors that each accept PCBs having a narrow variation in thickness, such as 0.2mm may be an acceptable solution in certain circumstances. However, such a solution quickly becomes unattractive if an end-user wishes to be able to remove one PCB and substitute another in its place. The end-user may have to purchase the range of connectors and chose which connector is perceived to be the most suitable. The requirement to correctly select the appropriate connector based on the thickness of the PCB is unattractive in such cases where interchangeability is desired as it will inevitably lead to situations where a specific PCB would be used in an unsuitable connector. As a result, interchangeability is not guaranteed and damage of the connector and/or the PCB would most likely happen as the connector is not "foolproof, i.e., end-users would forcibly insert a thick PCB into a connector not suitable for thick PCBs.

A further consideration is to try and reduce the occurrence of fretting motion. Fretting motion is micro motion between the mating elements which in this case are the electrical contacts within the connector and the PCB, more specifically, the PCB contact area. The fretting motion leads to fretting wear which is where the surface coating/plating is worn through. The fretting wear typically results in highly resistive corrosive products being formed in the contact interface. Fretting corrosion occurs at the interface between the connector and the PCB. The metal at the PCB side is the material which corrodes as the result of the movement of the connector relative to the PCB contact area. In an effort to reduce the occurrence of such fretting corrosion, contacts may be coated with a noble metal plating. This does not prevent fretting corrosion, but it does delay the onset as the corrosion does not start until material under the noble metal plating has been exposed by micro motion at the mating surface. An increase in electrical resistance due to fretting corrosion and the debris associated therewith, may result over time in micro-arcing, such micro-arcing leads to an increase in resistance and a corresponding temperature rise. The temperature rise may eventually lead to a thermal runaway situation. The excessive heat causes the corrosive effect of the debris to increase which leads in turn to an increase in resistance which again leads to an increased temperature and so on in a circular relationship until the part fails. This failure may cause a fire risk.

The most common cause of fretting corrosion is the relative movement between the contact elements, such movement may be very small but coupling with a vibration frequency may quickly exacerbate the issue. Thermal expansion and contraction between system components also leads to relative movement between the contacts. It can be seen that in order to reduce the occurrence of fretting, the motion related to the thermal expansion of the PCB and/or the connector must be limited, and vibration and consequent relative movement must be reduced as much as possible.

PCBs often have a high thermal load imposed upon them if LEDs are located on the PCB. In such cases it is important to the lifetime of the LED itself that heat is transported away from the LED and it is important to the reduction of the fretting motion that thermal expansion differences between the PCB and the connector are limited as much as possible.

In another embodiment, the connecter may have contacts that can accommodate PCBs with such differing thicknesses. The contacts may be resilient and may move in a vertical direction. As the contacts are resilient, a thicker PCB would result in the contact being deflected away from the rest position more than a thinner PCB would. The resilience of the material and the physical shape of the contact have to be carefully optimized so that the correct amount of force is exerted on the contact area(s) of the PCB. Too much force may damage both the PCB and the electrical contacts within the connector whilst too little may lead to fretting motion and/or arcing between the contacts and the contact areas and the abovementioned problems associated therewith.

In a yet further embodiment a stiffener may be added to the thinner PCB so that the part that is inserted into the connector is the same thickness as the thick PCB. This embodiment may require the manufacturer of the PCB to attach the stiffener to the PCB, such attachment may be, for example, glue or screws, clips etc. The solution may add cost to the PCB which may reduce its attractiveness in certain situations. Furthermore, if the stiffener is placed on the top of the PCB it will require "cut-outs" in the stiffener to allow the contact within the connector to directly contact the contact areas on the PCB. Conversely, the use of the stiffener on the bottom of the PCB may remove the necessity of the cut-outs as the stiffener is not masking the contact areas of the PCB but it may result in an airgap between the base of the luminaire and the bottom of the PCB as a result of a step in the PCB thickness. This airgap may act as an insulator and may reduce the thermal conductivity between the LEDs and the heatsink. This gap can be filled with a Thermal Interface Material (TIM) that is inserted between the bottom of the PCB and the base of the luminaire in order to increase the heat transfer from the LEDs (the heat producing devices) and the heatsink (the heat dissipation structure).

TIMs are available in a variety of forms; a thermal grease, thermal glue, thermal gap filler, and a thermal pad. The thermal grease has a very thin bond line and thus a very low thermal resistance. However, the grease has no mechanical strength and will rely on an additional fixation mechanism to hold the PCB in place relative to the connector and the base of the luminaire. The thermal glue also allows a very thin bond line but will additionally provide some mechanical fixation to the PCB after curing. Thermal gap filler allows a thicker bond line than either the thermal grease or thermal glue as it cures but it still allows an easier disassembly than thermal glue due to limited adhesiveness. Thermal pads come in a multitude of sizes and thicknesses and has the advantage of being easy to apply, it does however, require a larger force between the PCB and the luminaire base to ensure adequate thermal transfer. In the instances where interchangeability is desired, a TIM would need to be supplied with the thin PCBs and the person interchanging the PCBs would be expected to apply the TIM when the thin PCB is used.

In a further embodiment, the connector may have manual control of the stiffness or position of the contacts within the connector. The manual control has the advantage that the force exerted by the contact on the contact areas of the PCB can be finely controlled but a corresponding disadvantage is that additional tooling, such as a screwdriver may be required in order to manually adjust the contacts.

In various embodiments, the base of the luminaire can be considered to be an example of a heat dissipation structure. Equally, a wall of the luminaire can be considered to be an example of a heat dissipation structure. The wall of the luminaire is a broad term encompassing surfaces as well as structures that extend in a direction away from the base of the luminaire. In a further embodiment the wall of the luminaire may be a mounting structure for mechanical location whilst not providing a thermal path. This wall may be, for example, a plastic wall and the thermal load generated by the LEDs is dissipated by a further structure. This further structure may be the luminaire base or a separate heatsink. In an embodiment the heatsink may be considered as a planar heatsink. That is to say, at least a region of the heatsink is planar. The entire heatsink may be planar or the planar region of the heatsink may be a region of another component that is planar and acts as a heatsink. This may be part of the luminaire housing, for example, the wall of the luminaire or the base of the luminaire.

In an embodiment, the heatsink may be part of a heat dissipation structure. This heat dissipation structure may be a plurality of separate parts that form a structure, for example, a luminaire housing. The heat dissipation structure may be part of a curved wall or a facetted wall. The wall may be angled in relation to a further part of the housing, this wall may be a separate part, or it may be formed from a single piece and curved or folded as required.

In a yet further embodiment, a clip may be used to increase the thickness of the thin PCB to match that of the thick PCB. Such a clip may be slid over the end of the thin PCB before insertion into the connector. However, this may again lead to the situation where an airgap is present between the bottom of the PCB and the base of the luminaire.

Alternatively, the PCB may be inserted into the connector and the clip is then slid into the connector, the clip has two end positions corresponding to the two different PCB thickness ranges. This requires the end user to ensure that the clip is inserted to the correct end position, if this not correctly completed, the contact force may not be correct and the reliability issues discussed above may occur.

In a yet further embodiment, the connector may contain electrical contacts which automatically adjust to the differing thickness ranges, these contacts may slide into a different position and a spring may be used to bias the contacts into the position that is suitable for the thin PCB whilst the insertion of a thick PCB will displace the contact against the biasing force.

In another embodiment, the connector has mechanical registers that are located on the bottom face of the opening in the connector body. These registers are intended to constrain the PCB within the connector and may be arranged parallel with each other. The mechanical register may be considered as a mechanical stop. This means that the mechanical register impinges upon at least one feature of the PCB. This may be an edge, a face, an end, a surface protrusion etc., the impingement provides a positive mechanical stop to any further travel of the PCB beyond that point. The PCB may have a tongue section that protrudes from an end of the PCB or the entire PCB may be the same width throughout. If the PCB has a tongue section then it is preferred that the contact area is also located on the tongue section. This entire tongue section may then be arranged to slot into the opening of the connector, (the connection region). The connection region may be tailored to fit between the mechanical registers or it may be designed such that the width of the tongue is less than the opening in the connector but greater than the distance between the registers. This may mean that the PCB rests on top of the mechanical registers. The mechanical register may be formed as a singular item, one of a pair or one of a plurality of mechanical registers. If a single mechanical register is utilized then the relevant distance will be between the mechanical register and an opposing surface within the connector body.

In one embodiment, the mechanical register may be an L-shaped part. This part may be L shaped when viewed end on, such that when the connector body is viewed and the observer looks into the opening, one of the branches of the L extends up the sidewall of the connector body.

In a further embodiment, the L-shaped part may be L-shaped when viewed top down. That is to say, if the connector body is viewed from the top, one of the branches of the L may extend towards the opening in the body whilst the other branch of the L may extend across the back wall of the connector.

In a further embodiment the mechanical register may be a T-shaped part. The

T may be arranged inside the opening in the connector body with the upper branch of the T on the lower face of the opening.

In an embodiment the mechanical register may be a separate part which is inserted into the opening in the body of the connector. This separate register may be affixed in place with any known methods.

In a further embodiment the mechanical register may be integrated into the connector body.

In embodiments the mechanical registers are manufactured in plastic or metal.

The PCB may then be designed such that the connection region width is selected based on the thickness of the PCB, for example, a PCB with thickness of 0.8mm - 1.4mm may have a certain width of the tongue portion, whilst a PCB with a thickness of 1.4mm - 2.0mm may have a width of the tongue portion which is different to the width of the tongue portion of the thinner PCB. It can be seen that if the distance between the mechanical registers is chosen in cooperation with the choice of the width of the tongue portion then a relationship is formed between the distance between the mechanical registers, the width of the tongue portion and the subsequent final position of the PCB within the connector.

In a further embodiment, the body of the connector is located in an opening in a wall of the luminaire such that a driver may be connected. In order to ensure that adequate thermal transfer between the LEDs and the luminaire base or wall can occur then either a TIM may be inserted between the bottom of the PCB and the base or wall of the luminaire or more preferably, the connector may be allowed to move so that the differences in PCB thickness can be accommodated whilst still ensuring that the bottom of the PCB and the base or wall of the luminaire are still directly contacting each other. Such allowed movement may be a translational movement in a vertical direction whilst allowing a horizontal displacement. The vertical movement allows the use of differing thickness PCBs, whilst the horizontal movement is to allow for thermal expansion of the PCB and/or the connector and to reduce fretting corrosion.

In an embodiment, the connector is movable along a translational axis that is perpendicular to the plane of the heatsink. The plane of the heatsink may be considered as the plane of the planar region (i.e., the flat region) of the heatsink. Perpendicular may be considered to mean "the normal" of the plane. This movement may allow a range of positions along this axis, this may be a smooth movement from a first position to a subsequent position or it may be a range of positions along this axis. The range may be accompanied by tactile feedback to provide feedback to an operator that the position has been reached. The subsequent position may also be considered as a second position, a final position or a heat sinking position.

In an embodiment, the heatsinking position is the position in which the connector brings a PCB (which is arranged in the connector) into thermal contact with the planar heatsink.

In a further embodiment, the connector may be provided with biasing means to ensure that the PCB remains in thermal contact with the planar heatsink by ensuring that the connector is held in the heatsinking position. Such biasing means include, but are not limited to, a spring. Other biasing means are known to the person skilled in the art and may be used to equal effect.

In an embodiment, the opening in the connector body is provided in a face of the connector body that is substantially at the normal to the luminaire base. The PCB when arranged to be connected to the connector via the connection region may be parallel to the luminaire base. In a preferable embodiment, when the PCB is aligned substantially parallel with the luminaire base there is a thermal path from the PCB to the luminaire base and the luminaire base dissipates the heat generated by the LEDs on the PCB.

In a further embodiment, the opening in the connector body is provided in a face of the connector body that is substantially at the normal to the luminaire base. The PCB when arranged to be connected to the connector via the connection region may not be parallel to the luminaire base. It may be at an angle to the luminaire base, this angle may, in some embodiments, be such that the PCB is aligned parallel to the luminaire wall. In a preferable embodiment, when the PCB is aligned substantially parallel with the luminaire wall, there is a thermal path from the PCB to the luminaire wall and the luminaire wall dissipates the heat generated by the LEDs on the PCB.

In one embodiment, the heat is dissipated by the luminaire base, in another embodiment, the heat is dissipated by the luminaire wall, in a further embodiment, the heat is dissipated by a combination of the luminaire base and the luminaire wall. In a yet further embodiment, the heat is dissipated by a combination of the luminaire base or the luminaire wall in combination with a further heat dissipation structure, for example, a heatsink. In a yet further embodiment, the heat is dissipated by a combination of the luminaire base and the luminaire wall in combination with a further heat dissipation structure, for example, a heatsink.

In one embodiment, the body of the connector is located in an opening in a wall of the luminaire such that a driver may be connected. In order to ensure that adequate thermal transfer between the LEDs and a heatsink can occur then either a TIM may be inserted between the bottom of the PCB and a heatsink or more preferably, the connector may be allowed to move so that the differences in PCB thickness can be accommodated whilst still ensuring that the bottom of the PCB and a heatsink are still directly contacting each other.

In one embodiment the body of the connector is located in an opening in a wall of the luminaire such that a driver may be connected. In order to ensure that adequate thermal transfer between the LEDs and the luminaire base or heatsink can occur then either a TIM may be inserted between the bottom of the PCB and the base of the luminaire or heatsink, or more preferably, the connector may be allowed to move so that the differences in PCB thickness can be accommodated whilst still ensuring that the bottom of the PCB and the base of the luminaire or heatsink are still directly contacting each other. The movement may be allowed in a vertical direction whilst constrained in a horizontal direction. In one embodiment the body of the connector is located in an opening in a wall of the luminaire such that a driver may be connected. In order to ensure that adequate thermal transfer between the LEDs and the luminaire base or heatsink can occur then either a TIM may be inserted between the bottom of the PCB and the base of the luminaire or heatsink, or more preferably, the connector may be allowed to move so that the differences in PCB thickness can be accommodated whilst still ensuring that the bottom of the PCB and the base of the luminaire or heatsink are still directly contacting each other. The movement may be allowed in a horizontal direction whilst constrained in a vertical direction.

To promote interchangeability and interoperability, it may prove advantageous to ensure that the opening in the base of the luminaire is a standard size. This uniform dimensioning will allow manufacturers of luminaires to provide at least one opening in the base of the luminaire knowing that the connector will fit the opening and will subsequently, allow the use of PCBs with varying thicknesses within the luminaire. This interchangeability offers benefits of wider sourcing to the luminaire manufacturer and to repair and

upgradeability to the end user of the luminaire. These benefits may be especially attractive to an installer of the lighting systems and, also to the owner of the building that has the lighting system installed.

In an embodiment the luminaire further comprises a light exit window. This light exit window may be a virtual plane, i.e, there may not be a physical light exit window it may be a plane between the sidewalls of the luminaire. The light exit window may further comprise a diffuser located at the virtual plane.

In an embodiment, the LEDs, when in operation, may emit light towards the light exit window. Alternatively, the LEDs may be arranged on a side wall of the luminaire and, when in operation, emit light towards a further side wall.

The luminaire may be configured as an LED light strip including a housing, the housing may be a flexible housing. For example, the flexible housing may be a silicone extrusion or any other suitable material.

The luminaire may be configured as a panel light. A panel light may be a dimensioned to fit in a standard ceiling grid in an office or similar location. Such standard sized ceiling grids are commonly 600mm x 600mm in metric regions, such as Europe, and 2 foot x 2 foot in imperial regions, for example the USA.

The PCB may be a flexible PCB and may be for example, a flex- foil PCB. Alternatively the PCB may be rigid, for example, FR4 or MCPCB (metal core PCB), The luminaire may be configured as a retrofit bulb. That is to say an LED bulb including a housing. The bulb is an LED replacement that is designed to be fitted into an existing lighting socket whilst replicating the previously fitted conventional bulb. This may be a fluorescent lamp replacement (known as a TLED), a CFL (compact fluorescent lamp) an incandescent type bulb for fitting into a bayonet socket or an Edison socket.

In all embodiments discussed herein, the PCB may be the same width along its entire length, it may have a protruding portion (the connection region) that is thinner than the rest of the PCB or the protruding portion may be wider than the remainder of the PCB. The protrusion may be located at the end or anywhere along the PCB that is found to be suitable.

In all embodiments discussed herein, the heat dissipation structure may be one of; a base of the luminaire, a wall of a luminaire or a heatsink or it may be any combination thereof.

A housing may be configured as a luminaire or it may be another housing that is suitable for receiving electrical componentry.

BRIEF DESCRIPTION OF THE DRAWINGS

This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention.

As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of

embodiments of the present invention. Like reference numerals refer to like elements throughout.

Fig. 1 illustrates an orthographic view of a known connector

Fig. 2 illustrates a cross-sectional end view of the connector disclosed in

Fig. 1.

Fig. 3 illustrates a plan view of a PCB according to an embodiment of the present invention.

Fig. 4 illustrates a cross-sectional side view of the PCB disclosed in Fig. 3. Fig. 5 illustrates a plan view of a PCB according to another embodiment of the present invention.

Fig. 6 illustrates a cross-sectional side view of the PCB disclosed in Fig. 5. Fig. 7 illustrates a schematic side view of connector contacts according to yet another embodiment of the present invention. Fig. 8 illustrates a schematic side view of connector contacts according to yet another embodiment of the present invention.

Fig. 9 illustrates a cross-sectional plan view of a connector and corresponding PCBs according to yet another embodiment of the present invention,

Fig. 10 illustrates a cross-sectional plan view of a connector and corresponding PCBs according to yet another embodiment of the present invention.

Fig. 1 1 illustrates a cross-sectional plan view of a connector and corresponding PCBs according to yet another embodiment of the present invention.

Fig. 12 illustrates a cross-sectional plan view of a connector and corresponding PCB according to yet another embodiment of the present invention.

Fig. 13 illustrates a cross-sectional end view of a connector and corresponding PCB according to yet another embodiment of the present invention.

Fig. 14 illustrates a cross-sectional end view of a connector and corresponding PCB according to yet another embodiment of the present invention.

Fig. 15 illustrates a cross-sectional end view of a connector and corresponding

PCB according to yet another embodiment of the present invention.

Fig. 16 illustrates a side view of a connector, corresponding PCB and luminaire base according to yet another embodiment of the present invention,

Fig. 17 illustrates a cross-sectional plan view of a connector, corresponding PCB and luminaire wall according to yet another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

Fig. 1 illustrates an orthographic view of a known connector 10, the connector 10 further comprises a connector body 11 and a cover 12 which covers the electrical terminals (not shown). A PCB 20 is arranged to be inserted into the connector. The PCB comprises a connection region 21 and the connection region further comprises a contact area

(not shown). Fig 2 illustrates a cross-sectional end view of the connector 10. The connector body 1 1 contains cut-out regions 13 for housing electrical contacts 14. The electrical contacts are configured to provide an electrical connection between the electrical terminals and the contact areas of the PCB 20.

Fig. 3 illustrates a plan view of a PCB 20 according to an embodiment of the present invention. The PCB comprises a connection region 21 that has a width Wl that is narrower than the width W2 of the remainder of the PCB 20. The connection region could also be wider than the width W2 of the remainder of the PCB 20. The width W2 does not need to be a specific size in order to fit the connector, it is a free dimension that is determined by other design considerations of the system and not by the size of the opening in the connector body 11. The width Wl corresponds to the size of the opening of the connector body, the distance between mechanical registers (further discussed in relation to Figures 9 - 15) or between a single mechanical register and the side wall of the opening of the connector body 1 1.

Fig. 4 illustrates a cross-sectional side view of the PCB 20 disclosed in

Figure 3. The PCB 20 and connection region 21 have a thickness T 1. This thickness T 1 may be smaller for some PCBs 20 compared with others and in order to ensure an adequate contact pressure, to minimize the occurrence of fretting corrosion and to increase the interchangeability of PCBs 20 it may be desirable to add a stiffener 22. The overall thickness of the connection region 21 and the stiffener 22 is denoted by T2.

The PCBs 20 may be, for example, grouped into two groups based on their Tl thickness, such as PCBs 20 with a Tl of 0.8mm - 1.4mm being grouped in a first group and PCBs 20 with a Tl of 1.4mm - 2mm being grouped in a second group. The PCBs 20 in the first group may advantageously be provided with a stiffener 22 in order to increase the overall thickness T2 to a thickness falling in the range 1.4mm - 2.0mm, this thickness may be 1.7mm for example. The stiffener 22 may be placed on the top of the connection region 21 but will require additional features. Cut-outs may be provided in the stiffener 22 but this may not adequately solve the problem of contact pressure and fretting corrosion.

The stiffener 22 may be provided with contact areas that pass the electrical current from the connector contacts 14 to the contact area of the connection region 21. An alternative to adding the stiffener 22 to the top face of the connector region 21 is to add the stiffener 22 to the bottom face of the connection region 21. This placement may mean that the bottom face 23 of the PCB 20 is not planar with the bottom face 24 of the stiffener 22. This step change in the thickness of the PCB 20 and stiffener 22 combination may result in an air gap being present between the bottom face 23 of the PCB 20 and the mounting location.

The airgap may mean that thermal issues may need resolving, if LEDs are located on the top face 25 of the PCB 20 then a high thermal load is imposed on the PCB 20 and it is important to the lifetime and efficiency of the LED that the heat is transported away. The surface area of the PCB 20 may be sufficient to dissipate the heat by means of convection, alternatively, it may be desirable to increase the thermal conduction between the bottom face 23 of the PCB and the housing (not shown). In this case, a thermal interface material (TIM) may be used to fill the gap. If a TIM is to be used then it would be advantageous for the manufacturer of the PCB (or light engine) to supply a PCB 20 or light engine with a suitable TIM. This embodiment may require the end user or installer of the PCB to apply the TIM to the bottom face 23 of the PCB 20 before inserting the connection region 21 of the PCB 20 into the connector 10.

Fig. 5 illustrates a plan view of a PCB 20 according to another embodiment of the present invention. The PCB 20 comprises a connection region 21 that has a width Wl that is narrower than the width W2 of the remainder of the PCB 20. The width Wl corresponds to the size of the opening of the connector body 11, the distance between mechanical registers or between a single register and the side wall of the opening of the connector body 1 1. This width can be selected in order to provide a functional relationship between the distance between the mechanical register and a sidewall of the connector body (or a further mechanical register), the width Wl and the thickness of the PCB.

This functional relation may allow for the creation of groups of PCBs into sub ranges of thicknesses and the positioning of PCBs with thicknesses within the subranges in a desired position within the connector body.

Fig. 6 illustrates a cross-sectional side view of the PCB 20 disclosed in

Figure 5. The PCB 20 and connection region have a thickness Tl. The thickness Tl may, in this embodiment fall into the range of 1.4 mm - 2mm and therefore, no additional stiffener 22 is required. The contacts 14 within the connector 10 may be designed to exert adequate pressure on the contact areas of the PCB 20 and to reduce the likelihood of fretting corrosion occurring.

Fig. 7 illustrates a schematic side view of connector contacts 14 according to yet another embodiment of the present invention. The contacts 14 further comprise a first curved region 15 that is configured to slide across the top face 25 of the connection region 21 of the PCB 20. The PCB 20 has a thickness that lies in the range of 1.4mm - 2.0mm, this thickness means that the end of the connection region impinges upon a mechanical stop 26, also known as a mechanical register, and cannot be inserted any further into the connector body 1 1. The first curved section 15 of the contacts 14 slide across the upper face 25 of the connection region 21 until the first curved regions 15 of the contacts 15 are in contact with the contact areas of the PCB 20. The contacts 14 further comprise a second curved region 16. In this figure, it can be seen that, the connection region 21 of the PCB 20 does not pass under the mechanical stop 26 and therefore does not impinge on the second curved region 16 of the contacts 14.

Fig. 8 illustrates a schematic side view of connector contacts 14 according to yet another embodiment of the present invention. The contacts 14 further comprise a first curved region 15 that is configured to slide across the top face 25 of the connection region 21 of the PCB 20. The PCB 20 has a thickness that lies in the range of 0.8 mm to 1.4mm, this thickness means that the end of the connection region 21 passes under the mechanical stop 26 and does not impinge upon the stop 26. The first curved section 15 of the contacts 14 slide across the upper face 25 of the connection region 21 until the first curved regions 15 of the contacts 15 are in contact with the contact areas of the PCB 20. The contacts 14 further comprise a second curved region 16. In this figure, it can be seen that, the connection region 21 of the PCB 20 does pass under the mechanical stop 26 and therefore does impinge on the second curved region 16 of the contacts 14. The connection region 21 then forces the second curved region 16 upwards thus increasing the downward pressure of the first curved region 15 of the contacts 14 on the contact areas of the PCB 20. Due to the relative movement of the fulcrum position of the contacts 14 between Figures 7 & 8 an equivalent contact pressure is applied irrespective of whether the PCB 20 thickness lies in the range of 1.4mm - 2.0mm or 0.8mm - 1.4mm. Fulcrum in this case is intended to mean the point about which the contacts 14 pivot. This point may be a physical fixation or it may be a virtual point, i.e., the rotation may occur about the fulcrum point without the fulcrum being physically attached to an external part. The contacts 14 may be biased towards the PCB 20 or the contact itself may be made from a resilient material.

Fig. 9 illustrates a cross-sectional plan view of a connector 10 and corresponding PCBs 20 according to yet another embodiment of the present invention. The connector comprises a body 11 and an opening 17 in the body. This opening is configured to receive the connection region 21 of the PCB 20 and located within the opening are two mechanical registers 18. The distance between the two mechanical registers 18 may be selected to form a functional relationship between the width Wl of the connection region 21 of the PCB 20, the thickness of the PCB and the desired position of the connection region 21 of the PCB within the connector body 1 1. The connection region 21 of the PCB has a width Wl that is selected based on the thickness of the PCB 20. The width Wl may, for example, be a first width if the thickness of the PCB 20 lies in the range of 0.8mm - 1.4mm and the width may, for example, be a second width if the thickness of the PCB 20 lies in the range 1.4mm - 2.0mm. In this embodiment, the PCB 20 with a thickness of between 1.4mm - 2.0mm is shown at the bottom of Figure 9 and it has a width Wl of the connection region 21 that is less than the width Wl of the connection region 21 of the PCB 20 shown at the top of Figure 9. The top PCB 20 has a thickness of between 0.8mm - 1.4m. The width Wl of the connection region 21 of the bottom PCB 20 is selected to allow the connection region 21 to fit between the two mechanical registers 18 located in the opening 17 of the connector 10 whereas the width Wl of the connection region 21 of the top PCB 20 is selected to not fit between the two mechanical registers 18 but to fit into the opening 17 of the connector 10. This means that the connection region 21 of the top PCB is incident on the upper surface of the mechanical registers 18.

The height of the mechanical registers 18 in this embodiment may, for example, be 0.6mm. When the connection region 21 of the PCB 20 having a thickness of between 0.8mm and 1.4mm is inserted into the opening 17 of the PCB it will rest on the top surface of the registers 18 and the combined total thickness of the registers 18 and the connection region 21 of the PCB 20 would be between 1.4mm and 2.0mm. When the connection region 21 of the PCB 20 having a thickness of between 1.4mm and 2.0mm is inserted into the opening 17 of the connector 10 it will fit between the registers 18 and the thickness of the registers 18 will not be combined with the thickness of the connection region 21 of the PCB 20. This means that the top face 25 of the PCBs 20 will be between 1.4mm and 2.0mm from the base of the opening 17 irrespective of the thickness of the PCB 20 and that the contacts 14 can be configured to provide an adequate level of contact pressure to the contact areas of the PCBs 20 based on the smaller range of 1.4mm to 2.0mm rather than the larger range of 0.8mm to 2.0mm that would otherwise be required.

Fig. 10 illustrates a cross-sectional plan view of a connector 10 and corresponding PCBs 20 according to yet another embodiment of the present invention. The connector comprises a body 11 and an opening 17 in the body. This opening is configured to receive the connection region 21 of the PCBs 20 and located within the opening 17 are three mechanical registers 18. The connection region 21 of the PCBs 20 has a width Wl and a length that is selected based on the thickness of the PCB 20. The width Wl and length of the connection region 21 may be a first width and length if the thickness of the PCB lies in the range of 0.8mm - 1.4mm and the width and the length of the connection region 21 may be a second width and length if the thickness of the PCB 20 lies in the range 1.4mm - 2.0mm. The distances between the three mechanical registers 18 may be selected to form a functional relationship between the width Wl of the connection region 21 of the PCB 20, the length of the connection region 21, the thickness of the PCB and the desired position of the connection region 21 of the PCB within the connector body 11. In Figure 10, the PCB 20 with a thickness of 1.4mm - 2.0mm is shown at the bottom of the figure and the PCB 20 with a thickness of 0.8mm - 1.4mm is shown at the top of Figure 10.

The PCB 20 having a thickness of 1.4mm - 2.0mm (shown at the bottom of

Figure 10) has a width and a length of the connection region 21 that is less than the width and length of the connection region 21 of the PCB 20 having a thickness of between 0.8mm - 1.4mm (shown at the top of Figure 10). The width Wl and length of the connection region 21 of the bottom PCB 20 is selected to allow the connection region 21 to fit between the three mechanical registers 18 located in the opening 17 of the connector 10 whereas the width Wl and length of the connection region 21 of the top PCB 20 is selected to not fit between the three mechanical registers 18 but to fit into the opening 17 of the connector 10. This means that the connection region 21 of the top PCB is incident on the upper surface of the mechanical registers 18.

Fig. 1 1 illustrates a cross-sectional plan view of a connector 10 and corresponding PCBs 20 according to yet another embodiment of the present invention. The connector 10 comprises a body 11 and an opening 17 in the body. This opening is configured to receive the connection region 21 of the PCBs 20 and located within the opening 17 are two mechanical registers 18, in this embodiment, the mechanical registers 18 are not located around the periphery or along the sides of the opening 17. The PCB 20 shown at the bottom of Figure 1 1 has a thickness that lies in the range of 1.4mm - 2.0mm. The connection region 21 of the lower PCB 20 has two cut-out regions that coincide with the protruding registers 18. The PCB 20 that is shown at the top of Figure 1 1 has a thickness that lies in the range of 0.8mm - 2.0mm and the connection region 21 of this PCB 20 does not have the cut out regions. The width and length of the connection region 21 of the PCB 20 having a thickness of between 1.4mm - 2.0mm is the same as the width and length of the connector region 21 of the PCB 20 having a thickness of between 0.8mm - 2.0mm.

When the connection region 21 of the lower illustrated PCB 20 is inserted into the opening 17 of the connector body 17, the cut outs 27 accommodate the protruding mechanical registers 18 and the height of the registers 18 does not influence the total combined thickness of the PCB 20 and registers 18. Conversely, when the connection region 21 of the upper illustrated PCB 20 is inserted into the opening 17 of the connector body 17, the connection region 21 of the PCB 20 impinges on the protruding mechanical register and when fully inserted the connection region 21 will rest on top of the mechanical registers. In this case, the height of the registers 18 does influence the total combined thickness of the PCB 20 and registers 18. The distances between the protruding mechanical registers 18 is selected to form a functional relationship between the width Wl of the connection region 21 of the PCB 20, the thickness of the PCB and the desired position of the connection region 21 of the PCB within the connector body 1 1. As previously discussed, the height of the registers 18 may, for example, be 0.6mm so that the top face 25 of the PCB 20 having cut out regions 27 located in the connection region 21 and the top face of the PCB 20 without cut out regions 27 in the connection region 21 will be in the range of 1.4mm - 2.0mm from the bottom face of the opening 17 in the connector body 1 1.

Fig. 12 illustrates a cross-sectional plan view of a connector 10 and corresponding PCB 20 according to yet another embodiment of the present invention. The connection region 21 of the PCB 20 has two cut outs 27 which in this case are located on the sides of the connection region 21. When the connection region 21 of the PCB 20 is inserted into the opening 17 of the connector body 11, the distal end 28 of the connection region 21 will impinge upon two further features 19. These features may comprise a pin and when the distal end 28 impinges on the features 19 a greater force is required to continue the insertion of the connection region 21 into the opening 17 of the connector body 1 1. This greater force will mean that the connection region 21 will deform enough to pass the two features 19 and then the cut-out portions 27 will accommodate the features 19 thus allowing the connection region 21 to return to its non-deformed original shape. This combination of features may provide the user with so-called "tactile feedback" that the connection region 21 has been inserted to the correct depth inside the opening 17 of the connector body 11.

Fig. 13 illustrates a cross-sectional end view of a connector 10 and corresponding PCB 20 according to yet another embodiment of the present invention. The connector comprises a body 11 and an opening 17 in the body. This opening is configured to receive the connection region 21 of the PCB 20 and located within the opening are two mechanical registers 18. The distances between the mechanical registers 18 is selected to form a functional relationship between the width Wl of the connection region 21 of the PCB 20, the thickness of the PCB and the desired position of the connection region 21 of the PCB within the connector body 1 1. In this figure, the PCB 20 has a thickness of between 1.4mm - 2.0mm and the top face 25 of the PCB 20 is between 1.4mm and 2.0mm from the bottom face 31 of the opening 17 in the connector body 1 1.

Fig. 14 illustrates a cross-sectional end view of a connector 10 and corresponding PCB 20 according to yet another embodiment of the present invention. The connector comprises a body 11 and an opening 17 in the body. This opening is configured to receive the connection region 21 of the PCB 20 and located within the opening are two mechanical registers 18. In this figure, the PCB 20 has a thickness of between 1.2mm - 1.6mm and is resting on a face 32 of the registers 18. This face may be for example, 0.4mm from the bottom face 31 of the opening 17, therefore, the top face 25 of the PCB 20 is between 1.6mm and 2.0mm from the bottom face 31 of the opening 17 in the connector body 11.

Fig. 15 illustrates a cross-sectional end view of a connector 10 and corresponding PCB 20 according to yet another embodiment of the present invention. The connector 10 comprises a body 11 and an opening 17 in the body. The connection region 21 of the PCB 20 is inserted into the opening 17 of the body 11 and located within the opening 17 are two mechanical registers 18. In this figure, the PCB 20 has a thickness of between 0.8mm -1.2mm and is resting on a face 33 of the mechanical registers 18. This face may be for example, 0.8mm from the bottom face 31 of the opening 17 of the connector body. The combined height of the mechanical registers 18 and the thickness of the PCB 20 means that the top face 25 of the PCB 20 will be between 1.6mm - 2.0mm from the bottom face 31 of the opening 17 in the body 1 1.

Fig. 16 illustrates a side view of a connector 10, corresponding PCB 20 and luminaire base 40 or heatsink 47. The PCB 20 has a connection region 21 that is inserted into the opening 17 of the body 1 1. The bottom face of the PCB 20 is in contact with the upper face 41 of the luminaire base 40 or heatsink 47. The connector 10 further comprises mounting features 42 for attaching the connector 10 to the luminaire base 40 or heatsink 47.

In this embodiment, the mounting features 42 are shown as hooks that protrude through slots in the luminaire base 40 or heatsink 47. The mounting features 42 have a region 46 that is thinner than the remainder of the mounting features 42 and this thinner region 46 allows for a vertical movement of the connector 10 relative to the luminaire base 40 or heatsink 47.

Alternatively, the connector may be mounted to the planar PCB in any way that allows movement along a translational axis TA that is perpendicular to the plane P of the heatsink

The slot allows for a horizontal movement of the connector to allow for thermal expansion of the PCB and/or the connector and to reduce the occurrence of fretting corrosion.

The vertical movement of the connector 10 allows for differing thicknesses of PCBs 20 to be accommodated by the connector 10 whilst still ensuring a good thermal contact between the bottom face of the PCB 20 and the upper face 41 of the luminaire base 40 or heatsink 47. Furthermore, the contact between the PCB 20 and the luminaire base 40 or heatsink 47 allows for a more rigid location of the PCB 20 and can help to minimize movement of the PCB 20 relative to the luminaire base 40 or heatsink 47. The more rigid location brings benefits of more controllable light output (i.e., the optical performance of the LEDs) are not compromised due to warping or distortion of the board and movement due to vibration which may damage the componentry on the PCB 20, the soldering or the PCB 20 itself is reduced. The PCB 20 may be fixed to the luminaire base 40 or heatsink 47 by any known means of fastening, i.e., clips, screws, glue, tape etc.

In some embodiments, it may also be advantageous to allow horizontal movement of the connector 10 relative to the PCB 20 when the PCB is fixed to the luminaire base 40 or heatsink 47. This movement may be provided by a slot. The slot provides for horizontal movement which may allow for thermal expansion of the PCB 20 and the relatively differing rates of expansion between the PCB 20, the connector 10 and the luminaire base 40 or heatsink 47. In some embodiments, the luminaire base 40 or heatsink 47 may further comprise a pocket or recess in the upper face 41, this recess may accommodate the connector 10 and allow for a greater range of vertical displacements of the connector relative to the upper face 41 of the luminaire base 40 or heatsink 47.

In some embodiments, the connector 10 may comprise mechanical registers 18 in the opening 17 of the connector body 11. These mechanical registers are intended to function with the correspondingly sized PCBs 20 and will allow a larger range of PCB 20 thicknesses to be accommodated and adequately connected by the connector 10. The distances between the protruding mechanical registers 18 is selected to form a functional relationship between the width Wl of the connection region 21 of the PCB 20, the thickness of the PCB and the desired position of the connection region 21 of the PCB within the connector body 1 1.

The connection region 21 of the PCBs 20 has a width Wl that is selected based on the thickness of the PCB 20. The width Wl of the connection region 21 may be a first width if the thickness of the PCB lies in the range of 0.8mm - 1.4mm and the width of the connection region 21 may be a second width if the thickness of the PCB 20 lies in the range 1.4mm - 2.0mm.

A PCB 20, having a thickness in the range of 1.4 - 2.0mm has a width of the connection region 21 that does not impinge on the mechanical registers 18 when the connection region 21 is inserted into the opening 17 of the body 1 1. The vertical movement of the connector 10 relative to the luminaire base 40 or heatsink 47 allows the PCB 20 to contact the upper face 41 of the luminaire base 40 or heatsink 47 whilst the upper face 25 of the connection region 21 lies in the range of 1.4mm - 2.0mm from the upper face 41 of the luminaire base and 1.4mm - 2.0 mm from the lower face 31 of the opening 17 in the body 1 1 of the connector 10.

A PCB 20, having a thickness in the range of 0.8mm -1.4mm has a width of the connection region 21 that does impinge on the mechanical registers 18 when the connection region 21 is inserted into the opening 17 of the body 1 1 of the connector 10. The vertical movement of the connector 10 relative to the luminaire base 40 or heatsink 47 allows the PCB 20 to contact the upper face 41 of the luminaire base 40 or heatsink 47 whilst the upper face 25 of the connection region 21 of the PCB 20 lies in the range of 0.8mm - 1.4mm from the upper face 41 of the luminaire base 40 or heatsink 47and 1.4mm - 2.0mm from the lower face 31 of the opening 17 in the body 11 of the connector. Fig. 17 illustrates a cross-sectional plan view of a connector 10, corresponding PCB 20 and luminaire wall 43 or heatsink wall 48 according to yet another embodiment of the present invention. In this embodiment, the connector 10 is inserted into a vertical wall 43, 48 of the luminaire or heatsink. The regions 44 and/or 44' have sufficient flexibility to provide a snap fitting through an opening in the luminaire wall or heatsink. The opening in the wall 43 has a larger dimension in the vertical direction than the thickness of the connector 10. This larger dimension allows the connector 10 to move in a vertical direction to allow the use of different thickness PCBs 20 as discussed above in relation to other embodiments. This connector is not limited to use with power transfer, it may be used for interconnections between PCBs, connection between PCBs and electrical circuits and/or data transfer connections.

Claims

CLAIMS:

1. A luminaire comprising a connector (10) for connecting a PCB (20) to an electrical circuit, the connector (10) comprising,

a body (11),

an opening (17) in the body (11) for receiving the PCB (20),

- contacts (14) for providing an electrical connection between a power source and the PCB (20), and

mechanical registers (18) located within the opening (17),

wherein the luminaire further comprises a planar heatsink (40, 43, 47, 48), and

wherein the connector (10) is movable along a translational axis that is perpendicular to the plane of the heatsink, allowing the connector (10) to reach a heat sinking position wherein the PCB (20), when received by the opening (17), is in thermal contact with the planar heatsink (40, 43, 47, 48).

2. The luminaire according to claim 1, wherein the luminaire further comprises a housing and wherein the planar heat sink is at least a part of the housing.

3. The luminaire according to claims 1 or 2, wherein the connector is arranged to be biased into the heat sinking position.

4. The luminaire according to any preceding claim, wherein at least two mechanical registers are provided, the registers having a height of between 0.5mm and 1.5mm and a width of between 0.1mm and 0.7mm

5. The luminaire according to claim 4 wherein the mechanical registers are located on a lower face of the opening.

6. The luminaire according to any preceding claim wherein the mechanical registers are further configured to secure the PCB.

7. The luminaire according to any preceding claim , wherein the opening in the connector has a width in the range of 1.5mm to 15mm.

8. The luminaire according to claim 2, wherein the planar heat sink is at least part of a wall of the housing, or at least part of a base of the housing.

9. The luminaire according to any preceding claim, wherein the planar heatsink is part of a larger heat dissipation structure.

10. The luminaire according to any preceding claim, wherein LEDs are located on the PCB.

1 1 The luminaire according to claim 10, wherein the LEDs, in operation, emit light towards a light exit window of the luminaire.

12. The luminaire according to claim 1 1, wherein the luminaire is arranged as a

LED light strip.

13. The luminaire according to claim 10, wherein the LEDs, in operation, emit light from a side wall of the luminaire to a further side wall of the luminaire.

14. The luminaire according to either of claims 14 or 1, wherein the luminaire is a panel luminaire.

15. The luminaire according to any preceding claim, wherein the PCB is a flexible PCB.