THEREFOR

FIELD OF THE INVENTION

This invention relates to 3D printing.

BACKGROUND OF THE INVENTION

Digital fabrication is set to transform the nature of global manufacturing.

One aspect of digital fabrication is 3D printing. The most widely used 3D printing process is Fused Deposition Modeling (FDM).

FDM printers use a thermoplastic filament, which is heated to its melting point and then extruded, layer by layer, to create a three dimensional object. FDM printers are relatively fast, low cost and can be used for printing complicated 3D objects.

Such printers may be used for printing various shapes using various polymers.

To perform a 3D printing process, the printer is controlled using a print command file generated by computer aided design (CAD) software, and this controls how the filament is processed. The quality of the eventual product depends both on the CAD file used to implement the design and the printing filament used.

The 3D printing process may for example be performed over the top of an electronic module. The printing for example defines the aesthetic appearance of the product and/or it performs additional functions. For example, the module may be an LED module and the 3D printed part is an optical beam shaping or beam steering part. The quality of the eventual product thus depends also on the correct design of the original electronic module.

There is a desire to be able to guarantee product quality, but this may be difficult when the electronic module and printing parts (filament and CAD file) are sourced separately. There is also an issue of management of the rights of the designer of a 3D product. Electronic measures may be used to protect the digital design files for a three dimensional object, but these may be circumvented. Furthermore, for a simple 3D product design, the product shape can easily be reverse engineered to create a 3D printing file which generates the product shape. Copies of a 3D object can then be produced without the required permission. There is therefore a need for a product design and manufacturing method which reduces the simplicity, and hence the economic benefit, of copying a 3D printed product. The invention relates specifically to products which combine a base module (which base module may for example be an optical component) and an overlying printed structure.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples in accordance with an aspect of the invention, there is provided a method of manufacturing a product, comprising:

providing a base module, wherein the base module comprises at least one LED element, is the at least one LED element being offset from a center of the base module; and

printing a 3D structure over the base module, wherein the 3D structure includes a light blocking feature that extends over the center of the base module, the light blocking feature being opaque so that it would block or obscure a light output from a LED element being located at the center of the base module.

This method makes use of a non-standard LED base module, in particular with the LED offset from the center. The printed structure has a light blocking feature over the center. This means that most off-the-shelf LED modules could not be used with a copied print file, because the printed structure will block the light output. This approach thus adds a level of complexity to the copying process, since both the LED module and the design of the 3D printed structure are non-standard.

The 3D structure may further include an attachment feature for mechanical attachment of the 3D structure to the base module. This adds further complexity to the print structure to render copying more difficult.

In one example, the method comprises providing the base module in a recess of a base support, wherein the printing comprises forming the attachment feature as an overlap portion which extends on the base support and over at least one edge of the base module.

This means that a correct base support also has to be used as part of the manufacturing process. The base support and the base module may then be designed with cooperating design features to render copying more involved.

For example, the base module may comprise a central region and one or more flanges, wherein the printing comprises forming the overlap portion over the one or more flanges. This flange design of the base module is again non-standard so adds complexity but not cost to the manufacturing process.

The printing may comprise printing the base support, interrupting the printing to locate the base module in the recess, and continuing printing to print the 3D structure. This makes use of an interrupt printing process.

In another example, the method comprises providing the base module in a recess of a base support, wherein the base support comprises connection pins extending within the recess, the base module has openings corresponding to the connection pins, and the printing comprises forming the attachment feature as a printed structure over the connection pins .

The printing process completes pin connections. Again, this requires cooperating designs of the base module and the printed structure.

The base module may comprise an electrical circuit, wherein the electrical circuit is incomplete, and the printing comprises using a 3D printing filament arrangement including conducting portions, wherein the conducting portions of the 3D printing filament arrangement complete the electrical circuit of the base module.

This approach additionally provides a functional electrical link between the base module and the printed structure over the top. The printed structure completes the electrical circuit of the base module. This provides a more complex product design than a fully functional module with an independent printed structure over the top. As a result, it again becomes more complex to copy the product design.

The 3D printing filament arrangement may comprise a single filament with conducting and non-conducting regions, or it may comprise multiple filaments. Thus, the "conducting portions" may be part of one filament and other non-conducting portions may be part of another filament. In such a case, a dual head printer with two types of filament may be used.

The electrical circuit of the base module may comprise a conductor track with an interrupt, and wherein the printing provides a short across the interrupt.

This provides a simple way to link the module function to the printing. It does not add significant complexity to the module or to the printing process but it renders copying more complicated, in that a conventional module design or a conventional printing process will not be suitable.

The method may comprise providing a solder resist layer over the electrical circuit, with contact holes at the locations of the ends of the conductor track adjacent the interrupt, to form open pads. This makes it more difficult for the interrupt to be corrected by soldering (i.e. a short circuit being introduced), because the interrupt itself is covered in solder resist. The interrupt may be formed as a series of breaks. This makes it more complicated to correct the interrupt manually as there are then multiple short circuit bridges that need to be made.

The method may comprise further printing over (i.e. on top of) the short. In this way, if the short has been made manually in an attempt to circumvent the copy protection measures, for example by soldering, wire bonding, welding, or conductive gluing, the printing process may not then function because the underlying substrate profile has changed.

The electrical circuit of the base module may comprise a first conductor track with an interrupt and a second conductor track within the interrupt, wherein the printing provides a dielectric layer over the second conductor track and a short across the interrupt over the dielectric layer.

This requires a two-stage printing process to correct the interrupt (i.e. provide the required electrical connection), rendering the product more difficult to copy.

The method may comprise forming a connector track, wherein the base module is provided over the connector track, and wherein the printing provides a connection of the conductor track at each side of the interrupt down to the connector track.

In this way, the connection is beneath the module and the printing provides electrical connections at the edge of the module.

Examples in accordance with another aspect of the invention provide an LED lighting unit, comprising:

a base module, wherein the base module comprises at least one LED element, is the at least one LED element being offset from a center of the base module; and

a printed 3D structure over the base module, wherein the 3D structure includes a portion that extends over the center of the base module, the portion being opaque so that it would block or obscure a light output from a LED element being located at the center of the base module.

This design is complicated to copy, in that a non-standard 3D structure and a non-standard base module design are used and this 3D structure and module design are co- designed for that purpose. One module design might match multiple 3D structures as to allow the fabrication of a group pf LED lighting units.

The 3D structure may further include an optical feature for processing the light output of the at least one LED. This may be a refractive or reflective component, or indeed any type of beam shaping or redirecting (such as beam collimating or beam scattering) optical component.

The 3D structure may further include an attachment feature for mechanical attachment of the 3D structure to the base module.

In one example, the lighting unit comprises:

a base support having a recess, wherein the base module is provided in the recess,

wherein the attachment feature comprises an overlap portion which extends on the base support and over at least one edge of the base module.

In another example, the lighting unit comprises:

a base support having a recess, wherein the base module is provided in the recess,

wherein the base support comprises connection pins extending within the recess, the base module has openings corresponding to the connection pins, and the attachment feature comprises a printed structure over the connection pins.

As explained above, the base module may comprises an electrical circuit and the 3D printed structure has conducting portions which complete the electrical circuit of the base module. The product then has electrical functionality which is defined by the combination of the base module and the printed structure over the top.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 shows a fused deposition modeling printer;

Figure 2 shows a first example of a base module and printed structure to complicate efforts to copy the design;

Figure 3 shows steps of a manufacturing method;

Figure 4 shows a further example of a feature used in a base module and printed structure to complicate efforts to copy the design;

Figure 5 shows difficulties which arise if trying to provide copying;

Figure 6 shows a further example of a base module and printed structure to complicate efforts to copy the design;

Figure 7 shows a further example of a base module and printed structure to complicate efforts to copy the design; Figure 8 shows a method of manufacturing a product; and

Figure 9 shows a product having a base module and a 3D printed structure over the top.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides a method of manufacturing an LED lighting unit in which a base module comprises at least one LED which is offset from a center of the base module. A 3D structure is printed over the base module having a light blocking feature over the center of the base module. This provides an overall device design and manufacturing method which is more difficult to copy.

Figure 1 is used to explain the operation of a fused deposition modeling printer.

A filament 10 is passed between a pair of driver wheels 12 to a printer head 14 having an output nozzle 16. A layer 18 of the material is deposited while in a high viscosity liquid state, which then cools and cures. A 3D structure is built up as a sequence of layer patterns.

The invention relates to product designs that have an electronic base mode and a printed structure over the top. It provides a functional link between the base module, for example an LED engine, and the printed structure, which is defined by the CAD print file (and filament design). By making the combination of the specific base module design and CAD print file a prerequisite to be able to print the final envisioned product properly, copying is made more difficult. An end-user is required to purchase both a CAD file and the matching LED module. The aim of the design is to make the complexity of counterfeiting less worthwhile given a low cost of the end product.

Figure 2 shows a first example of a base module and the way the printing completes the electrical functionality of the base module.

The image on the left shows the LED base module 20. The base module 20 comprises two LED elements 22 and external contact pads 24. Conductive tracks 25 connect the contact pads 24 to the LED elements 22.

The LED elements are both offset from the center of the base module 20. This means they are positioned away from the typical location of the LED of a module, which is in the center. The center of the base module may be the center of area, for example the standard center of the module when it has a regular shape (e.g. the center of a square or rectangle). If there are attachment features (as in examples below) these may be ignored so the center is the area center of the remaining main body of the base module.

The image on the right shows a portion 21 of a printed structure which extends over the center of the module 20. The printed structure portion 21 is opaque so that it would block or obscure the light output from a central LED. The printed structure portion 21 is one part of a 3D structure, which may for example perform an optical beam shaping function.

Thus, there are other portions of the printed structure either to the sides of the LEDs (such as reflectors) and/or over the LEDs 22 (such as a lens). The base module may for example require (e.g. for reasons of aesthetics or efficiency) that a part of its area is covered by reflective printed plastic. For this same purpose the LED module might be on purpose made low in efficiency, e.g. by removing a white solder resist reflection layer, at the location of the later portion 21. In this way, the portion 21 is desired to be present in the subsequent printing process, even for the desired functioning of the correct base module.

If a single filament print process is used, only opaque reflective portions may be needed in which case the printing is not over the locations of the LEDs.

The portion 21 may also function as an attach strip which performs the function of mechanically coupling the LED module 20 to the 3D printed structure. The printed layer (and the corresponding CAD file) then has the function of mechanically attaching the assembled LED module. The particular LED base module design and the unique print CAD file are such that an off-the-shelf module would lead to blocking the light emission from the LED.

In addition to having non-central LEDs, the base module may have an asymmetric form factor, and/or have two or more LEDs as shown instead of the normally expected single LED module.

Figure 3 shows a process flow for printing a structure which functions both as a light blocking element for a central location and for attaching the printed structure to the base module 20.

The top image on the left shows a first printed structure 23 which has a recess 23 a designed to receive the base module 20. The printed structure is for example formed on a base part of a luminaire.

The printing process is interrupted to mount the base module 20 in the recess as shown in the second image on the left. The base module 20 has a pair of flanges 20a, 20b extending outwardly from a rectangular main area. The recess 23 a is shaped to correspond to the shape of the base module 20. The third image on the left shows printing of first and second portions 21a, 21b. The first portion 21a overlaps the flanges 20a, 20b and the second portion 21b is at the center of the base module 20 between the two LEDs 22. The second plan view shows the resulting structure.

The bottom image on the left shows printing of third portions 21c. These portions (which may in fact be a single annular shape) functions as an optical reflector or collimator for performing beam shaping of the LED output.

The mechanical connection features are preferably different to the mechanical attachment used in a standard module. A specific CAD file is needed that matches the LED board geometry and features.

The example of Figure 3 is based on the use of flanges at edges of the LED base module 20. This feature can be realized by simply adapting the cut-out shape of the printed board. During the 3D printing process, the LED base module is embedded in the print (using an interrupted printing process), and the flanges become embedded and secured by the subsequent printing step. If a different LED base module is used, the LED module will not get properly mechanically attached in the product.

An alternative option is to provide holes in the board of the base module 20 and pins in the first print cycle which extend upwardly with the recess 23 a. The first print cycle thus includes the formation of guiding pins. The specially designed LED base module 20 is then placed over these guiding pins, requiring the use of a LED module with drilled holes (e.g. for an insulated metallic substrate board based LED module).

After placement over the pins, the pins may be leveled with e.g. a hot bar/tool, as to secure the mechanical attachment and as to allow consecutive print layers to be formed over the module. The pins and the subsequent layers thus function as an attachment feature.

Additional features for increasing the complexity to copy the design may be combined with the approach explained above.

Figure 4 shows an example of a base module 20 (with a single central LED 22) in which the 3D printing completes the electrical functionality of the base module.

Figure 4 is used to explain the option of completing an electrical circuit. This option can be combined with the approach described above by providing the LED or multiple LEDs at non-central locations instead of at a single central location as shown in Figure 4, which is simply for explanation.

The image on the left shows the base LED module 20. The base module 20 again comprises an LED element 22 and external contact pads 24. Conductive tracks 25 connect the contact pads 24 to the LED element 22. The conductive tracks are part of an electrical circuit of the base module. However, the circuit is incomplete, by which is meant there are missing connections to make the circuit functional. In the example shown, there are three breaks 26 in one of the conductive tracks 25. These three breaks together define what will be termed an interrupt, i.e. an open circuit region.

Each part of the conductive track ends at a break 26 with an enlarged track portion forming a conducting pad. The electrical circuit substrate is covered with a solder resist layer, but there is an opening at the enlarged conducting pad, thereby defining open pads 27. The solder resist layer thus has contact holes at the locations of the ends of the conductor track adjacent the break.

The solder resist layer is also open at locations where the LED element and other electrical components are mounted, and where there are other pads that need to be connected to the rest of the product, for example to the driver cabling.

The 3D printer is controlled to print using a 3D printing filament arrangement. Conducting portions of the 3D printing filament, or else a separate conducting filament, complete the electrical circuit of the base module 20. In particular, a conducting ribbon 28 is printed to create short circuits at the breaks 26.

This method provides a functional electrical link between the 3D printing process and the underlying module.

The printing process needs to use a conducting filament at the correct location/time. Thus, the overall product cannot be copied by using a more basic printing process to complete the module. This renders copying more challenging.

For example, it will be explained what will happen if it is attempted to create a short circuit with solder before completing the product with a more basic printing process. An elongate solder deposit (paste) can be applied, but during the melting process, for making a solder connection, the solder will wet the metal open pads 27 and will not form a ribbon of solder, because the solder resist (between the open pads 27) is non-wettable. In this case, the attempted copying would result in three solder balls, one on each of the three open pads 27.

Wire bonding to short circuit the breaks will also not work, as the wire bond has a loop. Because it is not flat, it is therefore not compatible with post-printing on top of that short circuit area.

The arrangement of open pads 27 is thus generally at the location of the interrupt, with the contact pads 27 separated by the breaks 26 in the conductive track. The breaks 26 in this particular example are covered in solder resist. In this example, the interrupt is in one of the main power supply lines from an external contact, but any other open circuit may be used which renders the circuit nonfunctional.

This design means the printing process has a required step of printing a conductive track onto (or nearby) the LED module such that an existing conductor track of the module is corrected so as to allow powering, or more generally correct operation, of the LED.

This method is of particular interest for product manufacturing that relies on dual-filament printing, so for product designs that already require printed conductors.

The printing method should be difficult enough that it would not be obvious how to circumvent the copy protection feature, for example by not allowing the user simply to add a solder wire to manually correct the interrupt.

The use of a daisy chain configuration of contact holes as shown in Figure 4 is a first option which renders this circumvention more difficult.

By providing a number of contact holes, across which conductive material is to be printed, counterfeiting with wire soldering is made much more complicated as explained above.

As explained above, although a counterfeiter might try to circumvent the open circuit by soldering wires, such action may be in vain if the subsequent material printing process steps become impossible because of non-flatness/non-planarity of the solder wire addition. This issue is explained with reference to Figure 5.

The left images show the correct process flow, starting with the base module 20 with the interrupt in the form of a single break 26 in a conducting track 25.

The short circuit 28 is created in the next step following which an insulating printed body 30 is formed. This body 30 has a part over the shorted interrupt.

The right images show the process flow in which it is attempted to cheat. The process flow starts with the base module 20 with the interrupt 26 in a conducting track 25. A wire bond 32 is then provided to restore functionality of the base module. However, the last step shows that this means the subsequent printing fails.

In this design, the subsequent over-printing over the short is made to be a key part of the printing process and the product design.

It is desirable to make the short circuit function performed by the printed structure hidden , for example obscured by a next print layer, so that it is not obvious from the complete end product that there is a requirement to print conductive shorts in order to create a product from that particular module design.. For this purpose, the subsequent printing is preferably on top of the short circuited region, i.e. over the location of the previous break 26, so as to make counterfeiting more difficult.

Figure 6 shows a method based on a dual printing function.

The base module 20 comprises a first conductor track 40 with an interrupt 43

(i.e. the break 26) and a second conductor track 42 which has a portion which extends within the interrupt. This portions lies between the ends of the first conductor track at each side of the break.

If the break 26 is simply shorted, there is then a likely contact to the second conductor track 42 which renders the device non- functional, in this example short circuiting the external contact pads.

To correct the interrupt, the printing provides a dielectric layer 44 over the second conductor track and a short 46 (shown dotted) across the break over the dielectric layer.

This means the printing is even more difficult to copy, in that it requires dielectric and conducting parts to complete the circuit of the underlying module.

Keeping these functional features flat means the surface remains compatible with the next steps in the printing process. Counterfeiting disturbs these next printing steps as well by changing the profile of the substrate. Counterfeiting is thus made more difficult to circumvent as two printing materials and a more complex printing method are used.

Figure 7 shows another example.

The process starts by forming a connector track 50 on a substrate. The track is for example formed on a base part of the luminaire. This base part could be an input part for the 3D printing process, or it might be the result of a preceding sequence of the 3D printing process.

The connector track 50 extends the full width of the base module 20 and projects laterally beyond two edges. They do not need to be opposing edges, and they may even be on the same edge, in which case the connector track may have a U-shape.

The base module 20 is then provided over the connector track as part of the base module assembly, as shown in the middle image.

The base module again has an interrupt, but the required connection is from one side of the module - the conductor track end 52 - to the another side of the module - the conductor track end 54. The interrupt may thus be considered to extend across the full width of the module in this example. It may instead be considered to extend between any two points around the periphery of the module. The two points may even be adjacent each other at the same side of the module.

The printing provides a connection 56 of the conductor track down to the connector track at each side of the interrupt.

In this way, the connector 50 is beneath the module and the printing provides electrical connections at one or more edges of the module. The short circuiting pathway is thus hidden under the LED module.

Figure 8 shows a manufacturing method for manufacturing an LED lighting unit.

In step 60, a base module is provided which comprises at least one LED which is offset from a center of the base module.;

In step 62 a 3D printing is carried to form a 3D structure over the base module. The 3D structure includes a light blocking feature over the center of the base module.

Note that the printed structure may provide additional electrical, optical or mechanical functionality in addition to performing a central light blocking function.

Figure 9 shows a lighting module comprising a base module 70 in the form of an LED engine and a printed structure 72 which provides beam shaping or collimation of the light output from the LED engine. This provides a low cost 3D printed integrated light module. The printed structure in this example is a refractive lens. The printed structure may instead be a reflective optical component.

The invention is of primary interest for low-price entry lighting elements, for example home-printed products.

The LED modules may be formed with other electrical elements. These other electrical elements may for example be driver modules and/or sensors and/or actuators.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.