TECHNICAL FIELD

The present disclosure relates to a display apparatus. In particular, but not exclusively, the invention relates to a display apparatus including at least one layer of display components. The display apparatus has particular but not exclusive application in a vehicle. Aspects of the invention relate to a display apparatus, a vehicle, and a method of manufacture.

BACKGROUND

Modern day motor vehicles have numerous different systems and subsystems which require electronic control units (ECUs), or controllers, to power and control their functionality. Examples of the control units required include those for the various air bags distributed around the vehicle cabin, interior lights, front and rear seats, the entertainment module and/or DVD players, parking aids, various motion and other sensors, the power steering unit, and the terrain and navigation systems, to name but a few. Further electronic control units are also required to control the powertrain and the vehicle engine. Many such control units require a display functionality to indicate to the user the status of a function of the vehicle and/or to provide a lighting effect to a user and/or to illuminate a user-interaction surface of the control unit.

As the sophistication of vehicles increases, the need for so many control units poses a challenge for vehicle manufacturers because of the need to find accommodation space within the vehicle to house the units. In some current vehicles there can be as many as 80 different control units distributed throughout the vehicle. In addition to the problem of space for housing the control units, the wiring for the units and the weight that the units contribute to the vehicle is also a disadvantage.

A particular challenge with known control units is the limitation of their shape and size which restricts where the units can be housed. Traditionally control units are formed of a printed circuit board containing various electronic components and wiring which are housed within a rigid casing. The units need to be hidden within the vehicle, for aesthetic and safety reasons, and are often located behind the trim panels in the cabin. However space is limited in these regions and the inflexible design of the packaging for the control units means they cannot readily be accommodated in restricted spaces.

There are numerous other scenarios where the bulk of a conventional control or display unit is not appropriate for use in evolving technology.

The present invention has been devised to mitigate or overcome at least some of the above-mentioned problems.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a display apparatus, a vehicle and a method of manufacture as claimed in the appended claims.

According to one aspect of the present invention there is provided a display apparatus comprising a flexible substrate carrying at least one layer of display elements; and a plurality of structural supports distributed throughout the layer of display elements, wherein the structural supports are configured to counter stress induced by flexing of the display apparatus at least during assembly of the display apparatus.

The display apparatus provides the advantage that it is convenient to manufacture and in the final version provides a lightweight yet robust control unit that occupies little accommodation space in the apparatus in which it is used. The display apparatus has particular application in a vehicle, wherein the layer of display elements may be configured to provide an indication of a function of the vehicle, for example a vehicle lighting system, the heating system, the entertainment system, the seating system, the airbag system, the sun roof, or the window, or to provide an attractive lighting effect. Alternatively, the display apparatus may be configured to provide information to a user about the status of a vehicle functionality or system of the vehicle, or may be used to provide an appealing lighting effect. Numerous other applications for the display apparatus are envisaged.

One benefit of the invention is that the display apparatus can be manipulated to adopt a variety of different shapes, depending on the requirements for the final product, due to its flexibility and robustness provided by the structural supports. For example, the control unit need not be flat and may be shaped to have a curved, undulating or non- planar profile.

The invention therefore provides a highly versatile display apparatus which can be adapted for use in a wide range of different applications.

In examples beyond vehicle use, the display apparatus may be used as a panel of a household appliance, such as electrical items in the form of washing machines, cookers or dishwashers and the like.

When used in a vehicle, the display apparatus provides the advantage that it is convenient to manufacture and in the final version provides a lightweight yet robust display apparatus that occupies little accommodation space within the vehicle. This is a particularly useful feature in modern day vehicles where vehicle functionality is high, and there is an ever increasing need for additional control functions.

In one embodiment, the substrate retains flexibility when the display apparatus is in use, and wherein the plurality of structural supports are configured to counter further stress induced by flexing of the display apparatus when in use.

It may be that at least one of the plurality of structural supports is deformed as the display apparatus is flexed, on assembly and/or in use.

By way of example, the structural supports are distributed in a regular array throughout the layer of display elements. For example, each display element may be separated from its neighbouring display elements by a structural support. The forming of the structural supports in a regular array is convenient to achieve using a printing apparatus.

Typically, the plurality of structural supports take the form of pillars. By way of example, the plurality of structural supports may take the form of V-shaped members. V-shaped members are particularly beneficial for distributing loads applied to the display elements as the display apparatus is flexed, thereby countering stresses in the apparatus. The plurality of structural supports may be formed from a transparent material. In this way the supports are not visible in the final product. For example, the plurality of structural supports may be formed from one or more of silicon, thermoplastic polyurethane (TPU), thermoplastic elastomers (TBE).

In some embodiments the plurality of structural supports may include electrically conducting supports. Alternatively, or in addition, the plurality of structural supports may include electrically insulating supports.

For example, the electrically insulating supports may be provided in a two dimensional array throughout the apparatus so as the electrically insulate at least one layer of display elements from current.

The display apparatus may comprise at least a first layer and a second layer of display elements arranged on the substrate, one on top of the other.

By way of example, the second layer of display elements may include a plurality of structural supports distributed throughout the second layer of display elements.

The structural supports of the first layer of display elements may, for example, be aligned vertically with the structural supports of the second layer of display elements.

It may be beneficial of the structural supports of the first layer of display elements are integrally formed with the structural supports of the second layer of display elements. In this case the structural supports can be formed as part of a printing process, as the layers of the display elements are assembled one on top of the other together with the structural supports. A two dimensional array of printing heads may be assembled to layer the materials of the display elements and the support structures, one layer at a time.

The display elements may include one or more of the following: OLED elements, LCD elements, TFT elements, capacitive elements, piezoelectric elements, AMOLED elements, OLCD elements. The display apparatus may include a polarising layer. The polarising layer may define a user-interaction surface.

The display apparatus may include an injection moulded layer on an upper one of the layers of display elements.

Alternatively, a laminate layer may be provided on an upper one of the layers of display elements.

In a particularly beneficial display apparatus, the flexible substrate defines a first flexible substrate, the display apparatus comprising a second flexible substrate carrying at least one layer of second display elements; and a plurality of second structural supports distributed throughout the second layer of display elements, wherein the second structural supports are configured to counter stress induced by flexing of the display apparatus at least during assembly of the display apparatus, and wherein the first flexible substrate defines one surface of the display apparatus and the second flexible substrate defines an opposed surface of the display apparatus, wherein the at least one layer of display elements and the at least one second layer of display elements are located between the first and second substrates.

The display apparatus is particularly suitable for use in a vehicle.

According to another aspect of the invention, therefore, there is provided a vehicle provided with the display apparatus of the aforementioned aspect.

According to a further aspect of the invention, there is provided a method of forming a display apparatus, the method comprising depositing a first layer of display element material on a flexible substrate, interspersed with a layer of structural support material,; and depositing one or more further layers of display element material on the first layer of display elements, interspersed with a further layer of structural support material, so as to build a first display element structure with structural support elements distributed throughout the first and further layers. The structural support elements are thus distributed vertically through the first and further layers of display element material. In a further step, the method may comprise depositing a second layer of display element material on the first display element structure, interspersed with a further layer of structural support material, and depositing one or more further second layers of display element material on the second layer of display element material, so as to build a second display element structure on the first display element structure, with the structural support elements extending through both the first and second display element structures.

The method enables a layered structure of different display elements to be built upon the flexible substrate, with the structural supports being formed at the same time as the display element material is deposited, one layer of material at a time to build up the supports, lending itself to a roll-to-roll type printing process.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a known vehicle to show the positions of various electronic control units located around the vehicle.

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 2 is a side view of a vehicle with which embodiments of the invention may be used;

Figure 3 is a perspective view of the interior of the vehicle in Figure 2, to show positions where the control unit of embodiments of the invention may be employed;

Figure 4 is an exploded view of a control unit which may be used in a vehicle of the type shown in Figures 2 and 3;

Figure 5 is a plan view of a printed electronics layer forming part of the control unit in Figure 4;

Figure 6 is a schematic cross section of the control unit in Figure 4 formed using a single shot injection moulding process;

Figure 7 is a schematic cross section of a control unit, also formed using a single shot injection moulding process;

Figure 8 is a schematic cross section of a control unit, formed using a twin shot injection moulding process;

Figure 9 is a schematic cross section of a control unit, also formed using a single shot injection moulding process;

Figure 10 is a perspective view of a control unit with only partial encapsulation of the printed electronics layer;

Figure 1 1 is a schematic perspective view of a control unit formed by a lamination process;

Figure 12 is a schematic cross section of a layered display structure which may be used in the control unit show in previous Figures;

Figure 13 is a schematic cross section of an alternative layered display structure to that shown in Figure 12 which may be used in other embodiments of the invention; Figure 14 is a perspective view of a portion of the layered display structure in Figure 12 or Figure 13 to show a support structure thereof;

Figure 15 is a perspective view of a portion of a layered display structure in an alternative embodiment to that shown in Figure 14 to show an alternative support structure for the layered display structure;

Figure 16 is a cross section of a support element forming part of the support structure in Figure 15;

Figure 17 is a schematic representation of a layered display structure as in Figure 12, to illustrate the loading on a support element during flexing of the electronics layer structure;

Figure 18 is a schematic diagram of a manufacturing apparatus which may be used to assemble the layered display structure of Figures 12 and 13;

Figure 19 is a schematic diagram of a manufacturing apparatus which may be used to assemble a different layered display structure to that in Figure 18; and

Figure 20 is a schematic cross section of an alternative electronics later structure to that shown in Figures 12 and 13.

DETAILED DESCRIPTION

Referring to Figure 1 , in a modern day vehicle the various functions within the vehicle cabin, together with the engine and power train systems, require numerous control units (or controllers) to be situated in already limited accommodation space within the vehicle. Figure 1 illustrates just some of the possible positions for the control units, some of which are identified with reference numeral 10, which may be distributed throughout the vehicle 12. It is not uncommon, for example, for a vehicle to be provided with in excess of 70 such control units 10, including those for the cabin lighting systems, the air bags, the sunroof, the roof blinds, the windows, the front and rear seats, the parking sensor system, various other sensor systems around the vehicle and the vehicle entertainment system.

Figure 2 is a side view of a vehicle 100 with which embodiments of the invention may be used to provide advantages over known vehicles. The interior of the vehicle is shown in Figure 3, where two possible positions for the control unit of the invention are identified. In one position the control unit takes the form of an overhead control unit, referred to as 10a, which may be used to control various vehicle functions, including lighting, a sunroof and/or blinds. In another position the control unit takes the form of a cover or lid for a glove compartment 10b, which has a curved surface profile. Various vehicle functions may be controlled using the control unit forming part of the glove lid compartment including, by way of example only, lighting, seating, heating, audio visual and satellite navigation functions.

Figure 4 is an exploded view of a control unit which, by contrast with existing control units, provides a compact and relatively light weight structure which can be housed more readily within the confines of the vehicle cabin. The control unit 10 comprises three elements or members; a first member 14 which defines a user-interaction surface for the user in the form of a presentation surface 16 which is visible to the user when the control unit 10 is installed in its operating location. The presentation surface may be referred to as the A-surface 16 of the unit.

The control unit 10 further comprises a second member 18 which defines a B-surface 20 of the unit, and an intermediate member in the form of an injection moulded layer 22 interposed between the first and second members 14, 18. Typically in a vehicle, reference to an "A-surface" is a surface which is presented to a user of the vehicle and/or with which a vehicle user interacts, for example for the purpose of initiating control of a function within the vehicle, whereas a "B-surface" is a non-interacting surface that is usually hidden from the view of the user. The A- and B-surfaces may be defined by opposed surfaces of the same member, or as is shown in Figure 4 may be defined by separate members 14, 18 which are separate from one another.

It will be appreciated from the following description that either the first or the second member may form the component-carrying member of the control unit 10 (i.e. that member upon which the electronic components are provided). The phrase 'member' may be taken to mean any part, element, layer or other component of the control unit.

The first and second members 14, 18 are generally plate-like members, but in other configurations may take the form of thinner members or simply a layer of material. The first and second members 14, 18 are pre-formed members which are pliable and flexible, at least during the assembly stages of the control unit, as will be described in further detail below. The pre-formed first and second members 14, 18 are placed in the injection mould prior to the injection moulding process which forms the injection moulded layer 22.

The A-surface is defined by a first thermoformed member 14 which is pre-formed by first heating a plastic sheet to a pliable temperature, and then laying the pliable sheet in a mould so that the plastic material adopts the shape of the mould before it is then cooled. Graphical features 24 (only a few of which are labelled) are applied to the A- surface 16 to provide features, such as icons or symbols, which provide an indication to the vehicle user about how to control various functions provided by the finished control unit. Typically the graphical features are applied by laying a printed layer into the mould to define the required graphical icons and symbols. A three-dimensional finger track or groove (17 is provided on the A-surface into which a user can place their finger to run their finger along the track, optionally applying pressure to the surface or through capacitive touch to initiate a control of a vehicle function as described in further detail below. The A-surface 16 typically defines a visible surface in the vehicle cabin with which the user interacts. For example, the A-surface may provide a surface of an arm rest, an overhead control panel, a tray table, a seat control switch pack, a glove box lid, or a part of the vehicle dashboard.

The B-surface 20 is defined by a second thermoformed member 18 which again takes the form of a pliable member, at least during the manufacturing steps of the control unit 10. The second member 18 is formed in the same way as described previously for the first member 14 and a plurality of active and/or passive electronic components and printed tracks or wires are applied to the member 18 using known techniques. Typical passive components take the form of resistors, capacitors, inductors and transformers and diodes, whereas typical active components are those which act upon a source of current, such as amplifiers, switches, light emitting diodes (LEDs), integrated circuits, memories and microcontrollers. Typically, the B-surface 20 may be provided with one or more of the following features; an integrated circuit, a microprocessor, light emitting diodes (LEDs), user-interactive components such as pressure sensitive track, grid sensors, resistors, antennae, capacitors, sensors, quartz clocks, inductors, and conductive prints or tracks for carrying current. Known techniques for printing of the wires and tracks onto the B-surface 20 include screen printing, flexo printing, gravure, offset lithography, inkjet, aerosol deposition or laser printing.

Being pre-formed, thermoformed parts, the first and second members 14, 18 are lightweight and robust in nature, and can be formed with an aesthetically pleasing shape, contour and/or finish. This is particularly relevant for the A-surface 16 which provides the interaction surface for the user and is visible to the user within the vehicle cabin. The thermoforming process also enables a whole host of different shapes to be achieved for the members 14, 18. For example, the first and second members 14, 18 are formed from materials which are pliable during the assembly stages so as to give them the desired shape for the injection mould. In other embodiments, the members 14, 18 may be formed from materials and/or may be of a thickness, which retains a degree of flexibility or pliability even when the control unit 10 is full assembled.

In Figure 4, the first and second members 14, 18 are generally planar with a slight curvature on their upper surfaces. In other examples, the members may be more fully curved or rounded, at least in part, as determined by the shape of the available accommodation space which they are intended to occupy within the vehicle. Typical materials from which the first and second members 14, 18 are formed include polycarbonate materials or thermoplastic polymer resins such as polyethylene terephthalate (PET). Other examples of injection moulding engineered thermoplastic materials include polyphenylene sulfide (PPS), polyether sulfone, acetals, polypropylenes, polyether imide (PEI), polyethylenes, polyphenylene oxide (PPO), acrylonitrile butadiene styrene, polyurethanes (PUR), thermoplastic elastomers, polyphthalamide (PPA), polyethylene naphthalate (PEN), polyimide (PI), including plexiglass.

In other examples the first and second members 14, 18 may take the form of vacuum formed elements or members, as opposed to thermoformed elements or members. Other pre-forming methods may also be used to produce the 'pre-formed' members 14, 18, prior to performing the injection moulding process.

As part of the manufacturing process, as the injection moulded layer is formed over the component-carrying member, the injection moulded layer and the component-carrying member can be shaped together to define the required shape for the end-product. Depending on the material that is chosen for the component-carrying member, the effect of providing the injection moulded layer on top is that the two materials tend to 'fuse' together so that in the final product the electronics are effectively embedded within, fused or integrated with the materials of the structure. In other words, it appears in the final product that the components are 'suspended' within the structure, moulded between the materials of the injection moulded layer and the component-carrying member. In some embodiments it may be that the 'layer' structure of the final assembled control unit no longer consists of distinct 'layers' at all.

Figure 5 shows one example of a B-surface 20 which may form a part of the second member 18 of the control unit 10 in Figure 4. When in situ within the vehicle the B- surface 20 may define at least a part of an overhead control panel for controlling various lighting functions in the ceiling of the cabin and operation of a vehicle sunroof and/or roof blinds, as mentioned previously.

The B-surface 20 is provided with a printed electronics layer 29 (also shown in Figure 4) including a first set 30 of four LEDs provided in a horizontal arrangement in a first zone (top left) of the surface, a second set 32 of three LEDs provided in a vertical arrangement in a second zone just to the right of the vertical centreline of the surface and a third set 34 of LEDs provided in an arc arrangement located adjacent to the second zone. It will be appreciated that the use of the terms horizontal and vertical in this description is made with reference to the orientation in the figures, but is not intended to be limiting.

The positions of the first, second and third zones on the B-surface 20 correspond to associated regions on the A-surface 16 which are provided with graphical features to identify the positions of the zones underneath when the members 14, 18 are assembled in a 'stack', as indicated in Figure 4. The four LEDs 30 in the first zone may typically take the form of low level illumination LEDs to provide mood lighting on the ceiling of the vehicle, or to illuminate other features of the control unit. The three LEDs 32 in the second zone may typically take the form of higher power LEDs providing task lights for the vehicle. Various other light sources may be incorporated on the control panel including LEDs for providing ambient lighting effects, LEDs for illuminating hidden-until-lit features, Emergency-call features (E-call features) or Breakdown-call features (B-call features), and LEDs for illuminating icons or graphical features which provide indicators to the user about various functions of the control unit 10.

The B-surface 20 is further provided with a hybrid integrated circuit 36 for controlling and powering the various electronic components 30, 32, 34. Conductive prints or conductive tracks (two of which are identified by 38) are printed on various regions of the B-surface to provide current to the various components 30, 32, 34. In practice a greater number of tracks may be provided than is necessary for each component 30, 32, 34, for reasons which shall be explained later. The conductive tracks 38 include copper tracks (e.g. forming part of the hybrid integrated circuit 36) which provide fast connections to the microcontrollers and microprocessors of the hybrid integrated circuit 36, and silver tracks which carry current from the hybrid integrated circuit 36 to the other components (e.g. components 30, 32, 34) of the printed electronics layer. The substrate for the printed electronics layer may take the form of a polyester (PET), polyethylene naphthalate, polyimide, or plexiglass.

A grid sensing region 40 is provided in a three-dimensional groove formed along the upper edge of the B-surface 20 which corresponds to the position of the aforementioned three-dimensional groove provided in the A-surface. The groove 40 is shaped to receive the groove formation 26 of the A-surface when the members 14, 18 are assembled together. In use, sliding movement of the user's finger along the groove 26 provides a variable control function, or 'slider' function (for example using a piezoelectric or capacitive touch function) which may be used in particular to control the opening of a vehicle sunroof, as described in further detail below.

In the centre of the B-surface 20, and in each of the four outermost corners, openings are provided, also referred to as 'gates' 44, into which a moulding material is injected in order to form the third member 22 between the first and second members 14, 18. The first and second members 14, 18 are first placed into respective injection moulds with their various features in place, as described previously, and then the material for the intermediate member 22 is injected through the gates 44 into the cavity between the outer members 14, 18. Typically the material that is injected between the first and second members 14, 18 is a polycarbonate material, or other material suitable for injection moulding. Such polycarbonate materials are highly robust and may be transparent. The material is injected into the cavity at high temperature and pressure, and is then cooled so that the material adopts the shape of the cavity between the first and second members 14, 18, to complete the three-layer structure of the control unit 10 shown clearly in Figure 4. Other suitable materials for the moulded layer include most polymers (resins), including thermoplastics, thermosets, and elastomers. The materials selected for the first and second pre-formed members 14, 18 may be materials which are bendable or foldable in their final state, or may provide a more rigid structure, depending on the application.

The position of the gates 44 is an important feature of the assembly in that the gates need to be positioned in areas where the high pressures and temperatures associated with the injection moulding process do not cause damage to any of the more sensitive and fragile electronic components on the B-surface 20. By way of example with reference to Figure 4, based on manufacturing process considerations the central gate position is advantageous as it allows a uniform distribution of the injection moulding material between the first and second members 14, 18, to define an intermediate layer 22 of substantially uniform thickness. The gates are positioned so as to disperse the pressure of flow evenly between the surfaces of the members 14, 18. However, it does place the injection point of the central gate in quite close proximity to some of the components on the B-surface 20 (e.g. the LEDs and the integrated circuit). In other examples it may be possible to remove the central gate 44 altogether, and to rely only on the corner gates to introduce the injection moulding material between the members 14, 18. However, a balance is needed between the higher pressures required to inject the material into the central region between the members, in order to achieve a uniform layer across the entire surface, and the need to protect sensitive electronic components on the B-surface from such higher pressures. It is most advantageous to locate the more sensitive active components, such as clocks, sensors, antennae and capacitors, in positions on the surface 20 that are remote from or spaced well away from the gates. Once the moulded layer 22 is formed between the two members 14, 18 the control unit 10 takes its final form, comprising the first member 14 defining the A-surface 16 with graphical features with which the user can interact, the second member 18 defining the B-surface 20 which carries the various electronic components controlled by the user interactions with the A-surface 16, and the moulded layer 22 between the first and second members to provide rigidity and structure to the unit.

Figures 6 and 7 are schematic views of two possible configurations for the control unit 10 which may be formed using a single shot injection moulding process in which the injection moulding material is introduced into the mould to form the intermediate layer 22 of the control unit 10, as described previously.

In Figure 6 the graphics layer is laid on the reserve side of the A-surface (which would be transparent to allow visibility of the graphics layer). On top of the A-surface 16, an additional hard coat 50 is applied as a protective surface as this is the surface that is exposed in the vehicle cabin and may be subject to scratches and knocks, in use. In this example the moulded layer 22 is approximately 2-3mm in thickness, so that the overall structure is relatively thin and lightweight in comparison with known electronic control units. The active electronic components 30, 32, 34 and conductive prints or tracks 38 are applied to the B-surface 20 at the rear of the structure, as described previously. The configuration shown in Figure 6 can be formed using a single-shot injection moulding process to form the intermediate layer 22.

In addition, a piezoelectric layer (not shown) may be laid immediately beneath the first member 14 (i.e. in intimate contact with or in very close proximity to the first member 14). The piezoelectric layer is a pressure-sensitive layer via which the underlying electronic components 30, 32, 34 are controlled by the user applying a pressure to the surface of the first member 14 to provide a piezoelectric control function for the underlying electronic components 30, 32, 34.

In other examples (not shown), electrode and dielectric layers may be provided in the layer-structure of the control unit 10 to provide a capacitive touch functionality for the unit. The electrode layer and dieletric layers may be provided by the conductive tracks (such as 38). In this configuration a small voltage is applied to conductive tracks on the second member 18, resulting in a uniform electrostatic field.- When a conductor, such as a human finger, touches the surface of the first member 14 a capacitor is dynamically formed with the conductive tracks. An underlying controller printed on the second member 18 can then determine the location of the user's touch indirectly from the change in the capacitance as a result of the touch. This in turn can be used to control the underlying electronic components 30, 32, 34. The three dimensional grooves 26, 40, and the slider function provided by a user sliding their finger through the groove 26 of the first member 14, may be implemented by means of a piezoelectric or capacitive touch function.

In practice the capacitive touch effect may be enhanced if a ground plane is incorporated into the structure at the rear of the second member 18 (i.e. on the opposite side to the moulded layer 22).

In the case of capacitive touch embodiments there is no need for intimate contact between an electrode layer and the first member 14 in the same way as for a piezoelectric-based activation, because the change in capacitance as a result of touch is enough to indicate control.

Many other layers may be incorporated into the structure to provide touch-sensitive or other user-control functions of the control unit 10, including resistive layers, piezoelectric layers, electromagnetic layers, Quantum Tunnelling Composite (QTC) layers, electric field (e-field) layers and RF layers.

Figure 7 is an alternative example of the control unit in which the need for the second member of the structure is avoided and the electronic components 30, 32, 34 and conductive prints or tracks 38 are formed on the reserve side of the first member 14 (i.e. the surface on the reverse of that with which the user interacts). In this case the control unit is built up by first applying the graphical features 24 to the rear surface of the first member 14 and then applying a hard coat 50 to the front surface of the first member 14 to provide the protective layer. The electronic components and conductive tracks 38 are then applied to the rear surface of the first member 14, and the assembly is placed into a mould. The injection moulded material (e.g. polycarbonate) is introduced into the mould to produce the injection moulded layer on the reverse side of the first member 14, encapsulating the electronic components 30, 32, 34 and conductive tracks 38. The control unit structure in Figure 7 can also be formed using a single shot injection moulding method to form the layer 22, as for Figure 6.

Figures 8 and 9 show alternative examples of the control unit which may be formed using a twin shot (2K) injection moulding method. Figure 8 is similar to the embodiment of Figure 6 in that the electronic components 30, 32, 34 and the conductive prints 38 are mounted on the second member 18 and are spaced from the front surface of the control unit by the moulded layer 22. However, the need for the first member is removed in this example. Instead, the graphical features 24 are laid into a mould and the second member 18 is laid into a facing mould. A first shot of injection moulding material is then introduced into the gates 44 to fill the cavity between the moulds, and the material is cooled and set. Using a second mould the hard coat 50 is then formed at the front face of the structure using a second shot of injection moulded material (i.e. the hard coat is formed directly onto the moulded layer 22).

Figure 9 is a further example in which a second shot of injection moulded material is used to produce enhanced depth effects at the front surface of the control unit 10. In this embodiment only one member 14 is required to support the electronic components 30, 32, 34 and conductive tracks 38. These components and tracks are applied immediately behind the graphical features 24 which are applied on the rear surface of the first member 14, as described for Figure 7. A first shot of injection moulded material is then applied into a mould to encapsulate the rear surface of the first member 14, together with the electronic components 30, 32, 34 and the graphical features 24. A second shot of injection moulded material is then injected into a facing mould to encapsulate the front face of the first member 14, and to define a relatively thick and transparent front layer 52. The depth of the transparent layer 52 on the front of the structure can be used to provide enhanced depth effects for the graphical features 24 on the rear surface of the first member 14. For example, the transparent layer may be provided with various cut outs or holes of varying shapes and depths to provide different illumination effects from the LEDs 30, 32, 34.

In other examples (not shown) the hard protective coating 50 applied to the front surface of the first member 14 may take the form of a veneer, such as a wood effect veneer, which matches or complements the trim of the vehicle cabin in which the control unit 10 is intended to be used. In this way the control unit readily lends itself to occupying a prominent location within the vehicle cabin, and as such can be accommodated within an arm rest, overhead panel or the dashboard, for example, due to its aesthetically attractive finish. For example, the veneer may take the form of any thin layer of suitable material, such as wood, carbon-fibre, polymer heat shrink plastic, metal, textile or leather.

Figure 10 shows a further alternative embodiment in which the encapsulation of the printed electronic components by the moulded layer 22' is only partial across a surface of the structure. This may be useful, for example, if the accommodation space for the control unit is particularly limited, and the unit can be located partially within an already enclosed and safe environment without the need for extra encapsulation across the entire printed electronics layer.

Because of the high temperatures and pressures of the aforementioned injection moulding process, and despite the careful positioning of the gate(s) away from the most fragile and sensitive electronic components, some damage may occur to the conductive elements or tracks as the injected material is introduced through the gate(s) into the mould cavity. For this reason it may be beneficial to locate active electronic components in positions away from the gates 44, and passive electronic components closer to the gates 44, as the passive components are less likely to be susceptible to damage.

In addition, some electronic components require a higher current for performance (e.g. higher powered LEDs), so it is beneficial to allow for redundancy of these tracks to ensure that, even allowing for some breakage or damage during the injection moulding process, enough current can be delivered to the components through the remaining tracks which are not broken or damaged.

For the reasons described above the selection criterion for where particular components are located may be to locate active electronic components away from the gates, and passive components in closer proximity to the gates. Another criterion may be to consider whether a component is critical for the desired functioning of the control unit 10. If a component is considered critical to the operation of a control unit (for example, an LED light that provides illumination for a control unit for an indicator), then it is beneficial to locate the critical component away from the location of the gate so that the likelihood of damage to the conductive tracks supplying current to the LED, and/or damage to the LED itself, is minimised. It is also beneficial to locate the more fragile copper conductive tracks of the B-surface further away from the gates, whereas the silver conductive tracks may be more robust to the high pressure flows through the gates during injection moulding.

Because the control unit is pliable during assembly, prior to the setting of the injection moulded material, a degree of flexing of the conductive tracks to the electronic components may occur during manufacture. Also, for examples in which the control unit maintains a degree of pliability following manufacture the risk of damage occurring to the conductive tracks, in use of the control unit, also remains. To counter any damage which may arise, it may be beneficial to provide an excess of conductive prints or tracks to provide some redundancy for the tracks in the event that such damage arises. In particular, redundant conductive tracks 38 may be provided in the regions local to the gate(s) 44, which are those regions most susceptible to damage as they experience the highest pressures. By providing for track redundancy in this way, it is possible to ensure that even in the event of breakages a suitable number of tracks is maintained so that the specific current requirements for the electronic components, and the impedance at the junction between the electronic component and the conductive tracks, is maintained as required.

Another problem which may arise is that the cooling and curing process which follows the high temperatures and pressures associated with the injection moulding process may lead to shrinkage and breakage of the tracks 38 due to the deformation of the underlying layer or substrate to which they are applied. Care therefore needs to be taken in selecting an appropriate ink viscosity for the conductive tracks 38 and the density of the track lines. The size and density of the tracks is dependent not only on the positioning relative to the gates, but also the electrical load requirements for the components to which the tracks connect.

As described further below, other methods of manufacturing the control unit may be employed to avoid the aforementioned problems altogether.

It will be appreciated from the foregoing description that the control unit described provides a robust, lightweight structure which lends itself to be located within a vehicle cabin where it is visible to the user due to the high-quality and versatile finish that can be achieved on the A-surface 16 with which the user interacts. One such application is the overhead control panel described previously and as shown in Figures 3 and 44. Other applications for the control unit include an arm rest control panel for controlling the vehicle windows or door locks, a centre console control panel for controlling the vehicle's entertainment system, a drop-down sun-visor with a lighting functionality, or as a lid of a glove compartment where a presentation surface can be presented to the user on the otherwise dead-surface of the glove compartment lid.

In embodiments of the invention when utilised in a vehicle, the invention may take the form of a display panel for presenting information to the user, such that the user interaction with the unit is the viewing of the unit by the user. For example, the control unit may be configured to control a hidden-until-lit feature of the vehicle whereby illumination of the feature by a light source (e.g. LED) of the control panel highlights the feature to the user which is otherwise not visible.

In any of the embodiments of the invention the materials and/or thickness of the various layers may be selected so as to ensure that the final assembled product of the control unit retains some flexibility or pliability. It is important that layers have a degree of pliability during manufacture, so as to enable the final product of the control unit to be manipulated into the desire shape during the assembly process. It may be beneficial for the control unit to adopt a rigid structure in its final form (e.g. by virtue of the first and second members, and the injection moulded layer 22, when set, being rigid), but in other embodiments it may be beneficial for the members and the injection moulded layer to retain some flexibility e.g. to permit bending of the control unit, in use.

The previously described control units are formed using an injection moulding process to produce the intermediate layer of the control unit (as in Figures 6 and 8) and/or the encapsulation layer(s) (as in Figures 7 and 9). In order to avoid the problems associated with the high temperatures and pressures of the injection moulding process, alternatively the control unit structure may be formed using a lamination process to replace the injection moulded layer with a laminate layer. Figure 1 1 is a schematic diagram to show a control unit 1 10 of one embodiment of the invention when formed using laminate layers. As described previously, the first member 1 14 defines an A-surface 1 16 which carries graphical features as indicators to the user about how to control the unit. The second member 1 18 defines a B-surface 120 which carries the various electronic components and conductive tracks (not shown in Figure 1 1 ). The third member 122, which is situated between the first and second members 1 14, 1 18, takes the form of a lamination layer such as a glue layer.

In order to assemble the control unit 1 10 using the lamination process the first member 1 14 is first pre-formed using a thermoforming process, as described previously, and is laid into a mould. The second member 1 18 is formed using a similar process, as described previously, and is laid into a facing mould. The glue layer 122 is then laid onto the first or second member. The glue layer is pre-warmed so that it is pliable, but is formed of a material that does not require excessive pre-warming to give the required pliability.

Once the glue layer 122 is laid onto the first or second members 1 14, 1 18 the mouldings are brought together to apply pressure to the parts, sandwiching the glue layer 122 between the first and second members 1 14, 1 18. Heat is then applied to the structure so that the glue moulds itself exactly to the shape of the first and second members 1 14, 1 18 and adheres the parts together. The presence of the glue on the second member 1 18 is beneficial in that it provides a protective layer for the electronic components and circuitry during the heating phase. Moreover, as the glue layer is heated its phase change from a more solid to liquid form takes energy away from the components and circuitry. Finally the assembled structure is cooled so that the glue 'sets' to fix the first and second members 1 14, 1 18 securely together in a rigid structure with the glue forming an intermediate layer 122 between them.

In another embodiment (not shown) in which a laminate glue layer is used to hold the members of the control unit together, the need for two base members 1 14, 1 18 may be removed if the graphical features are laid directly into a mould rather than applying them to a first member 1 14. The glue is then laid directly into the mould, on top of the graphical features, and is sandwiched together with the second member 1 18 to form a two-layer structure with the graphical features being embedded or imprinted on the surface of the glue layer.

One benefit of the glue lamination process is that the high temperatures and pressures required for the injection moulding process are avoided. In addition, there is no need to accommodate gates within either the first and/or second members 1 14, 1 18 as the glue is simply laid onto one of the layers in pliable form. The lamination process also enables the stacking of integrated circuit components onto the B-surface (or the reverse of the A-surface) which may not otherwise be achievable due to the high temperatures and pressures of the injection moulding process which would too readily deform the stacked circuitry. Suitable materials for the lamination process include resins, vinyls, and ethylene copolymer resins.

Other embodiments envisage a hybrid arrangement of a laminated control unit structure in one part of the vehicle which is integrated with a moulded control unit structure in a common assembly. For example the arm rest of the vehicle may include a moulded high gloss unit with a wood-effect veneer having the control functions of the A-surface, with the laminated unit being adjacent to it to provide the resting surface for the arm.

In one embodiment, the control unit may comprise two or three layers formed from a lamination process so that the layer upon which the electronic components and conductive tracks are printed is a flexible sheet or layer, rather than taking a rigid preform.

Figure 12 shows one possible configuration of the second member 1 18 which may be used to form a part of the control unit 10 in an embodiment where the control unit 10 includes a display apparatus. In this case the second member 1 18 takes the form of a layered display structure, or display element structure, which is formed by layering different display materials onto a thin base layer or substrate (backlight layer 73) to achieve the desired lighting functionality. The layered display structure 1 18 may then be used with an injection moulded layer 22 or a laminate encapsulation layer 122 as described previously, or alternatively may itself define a flexible display structure without the need for encapsulation/lamination.

The display elements are deposited onto the backlight layer 73 which provides a supporting substrate to the layer structure 1 18 and provides a source of 'backlight' illumination for the components laid on top. A transistor layer 72 is laid directly onto the backlight layer 73 and an array of Liquid Crystal Display (LCD) elements 74 is then laid onto the transistor layer 72. The transistor layer 72 forms the switching layer for the LCD elements to which voltages are applied, under the control of a microprocessor (not shown), to control the LCD elements in the desired manner. The LCD elements 74 may be deposited in the form of an ink and are interspersed with structural supports or bolsters 76 (two of which are identified), with one support 76 being located between adjacent LCD elements 74 so that each LCD element is separated from its neighbouring LCD elements by a structural support. A polarising layer 78 is laid over the LCD elements 74. An array of colour filter elements 80, typically RGB filter elements, is laid onto the polarising layer 78. The colour filter elements 80 are interspersed with further structural supports 82 in the same way as for the LCD elements 74. The structural supports 76, 82 may be formed from the same material, and indeed may be integral with one another so that they pass through each display element layer of the structure 1 18. Alternatively the structural supports in each layer may be separate in each layer and may be aligned with one another, in a vertical sense.

The materials of the structure are deposited, one layer at a time, so as to build up the structural supports and the display elements.

A second polarising layer 84 is then laid onto the colour filter elements 80 prior to applying an anti-reflective coating 86, such as glass or acrylic, to provide a suitable top surface finish to the second member 18. A heat transfer arrangement 88 in the form of a thermally conducting layer may be incorporated into the laminated structure also to transfer heat away from the electronic components, in use or during assembly. Other positions for the heat transfer arrangement 88 are possible, and it may be beneficial to arrange the hear transfer arrangement 88 next to light producing elements of the structure 1 18 where the most heat is generated.

The LCD elements 74 are operated in a manner known in the art by applying a voltage to the transistor layer 72 to control the switching of the liquid crystal molecules in each element, which in turn determines whether light passing through the first polarising layer 72 is transmitted through the LCD elements 74 or is blocked.

The LCD elements 74 interspersed with the structural support elements 76 may be formed using a conventional ink jet or 3D printing process. By way of example, the 3D array of printing heads used to form the LCD elements 74 may have a first liquid crystal material provided in selected ones of the printing heads and a second, different material provided in others of the printing heads so as to give a regular array of LCD elements with structural supports arranged in regular locations between them. Typically the second material from which the structural supports 76 are formed is a curable resin which may be cured, for example, by UV radiation. It may be advantageous for the resin to be a transparent material so that the structures are not noticeably visible in the final product. If the final display unit 10 is intended to have some flexibility, then the supports 76 may be formed from silicon to provide a degree of support but still the requisite flexibility also. In this case, the shape of each support 76 is selected so as to ensure that the supports 76 still provide the required robustness, even when the final structure is flexed. In particular, the shape of the supports 76 is chosen to ensure that pressure applied to the supports is distributed evenly across the supports, even when the assembly is flexed. For example, the supports may take the form of V-shaped structures, or pillars of oval or circular cross section which maintain the ability to provide support even when flexing occurs.

Figure 13 shows an alternative configuration for the layered display structure 218 to that shown in Figure 12. In this example a first substrate 100 is overlaid with a first layer 102 in the form of a TFT (thin film transistor) layer. A TFT is a transistor array which is capable of providing an improved addressability and contrast, compared to a conventional passive display matrix. A second layer 104 in the form of an OLED (organic LED) layer is then overlaid on the TFT layer 102. An OLED layer is an emissive electroluminescent layer in the form an organic compound that emits light in response to an electric current. A polarizing layer 106 overlays the OLED layer 104 i.e. the polarizer overlays the upper layer of the display elements. An electrode layer 105 is overlaid on the OLED layer 104 and completes the OLED circuit. The layers are relatively thin and the materials of the layers are selected such that the final structure 218 is flexible and pliable and can be maneuvered, bent or flexed into any desired shape or configuration.

As for the previous embodiment, in the configuration of Figure 13 the layered display structure 218 includes an array of structural supports or bolsters, two of which are identified as 176, which are distributed in an array to extend through the TFT layer 102 and the OLED layer 104 and which extend beyond the upper surface of the OLED layer to engage with the polarizer 106. The structural supports 76 in each layer therefore align with one another, in a vertical sense, and form a regularly array of supports which are distributed evenly throughout the structure. Alternatively, the structural supports in each layer may be integrally formed so that one the array extends through all of the layers.

Figure 14 shows the array of support elements 76, 176 of Figures 12 or 13 formed using a 3D printing process, as described previously, whereas in Figure 15 the structural support elements 76 are formed using a screen printing process. The supports 76, 176 may comprise a softer, more flexible material for flexible displays (such as silicon) or may comprise a harder, more rigid material (such as melamine) for rigid displays. The structural supports are typically formed from a transparent material so as not to influence the aesthetic appearance of the final unit.

If the layer structures 1 18, 218 are intended to have some flexibility, then the supports 76, 176 may be formed from silicon to provide a degree of support but still the requisite flexibility also. In this case, the shape of each support 76, 176 is selected so as to ensure that the supports 76, 176 still provide the required robustness, even when the final layer structure is flexed. In particular, the shape of the supports 76, 176 is chosen to ensure that pressure applied to the supports is distributed evenly across the supports, even when the assembly is flexed. This has the effect of countering stresses in the structure that are induced by flexing.

In other embodiments different materials with different properties may be deposited to form the display layers. For example, inks having conductive, resistive, piezoelectric, and semi conductive properties may be deposited on the substrate 73, 100 to form the layers of the structure, depending on the desired functionality. Other display layers which may be used may take the form of OLCD (organic liquid crystal display) layers, AMOLED layers, quantum dot display layers, electro wetting display layers, or electrophoretic or electrochromic layers. The layers of the display elements may be formed by using thin layers of different printed inks and materials and the layered structure retains flexibility in its final form. Typically, the layer 100 may be formed from a glass, plastic, leather or textile material, In the case of leather or a textile material, being porous, a barrier layer may be required on top to reduce the chance to contaminent going throught to OLED layer. The A-surface of the layered display structure (i.e. the upper surface of the polarizer 106) may be provided with an additional layer (not shown) which provides a protective coating for the surface, so as to prevent or reduce the effects of wear and tear due to user interaction with the surface. For example, the A-surface may be provided with a veneer which provides a degree of protection for the A-surface, and may also provide an aesthetic quality. Graphical features may also be provided on the A-surface, as in the previously-described examples, to provide an indication to the user about various control features of the structure (e.g. touch-sensitive features).

Referring to Figure 16, each of the supports 76, 176 may take the form of a V-shaped structure as this maintains the ability to provide support even when flexing occurs. Local pressures applied to the layered display structure 1 18, 218 during flexing are countered by the supports 76, 176 to ensure robustness of the final unit.

Figure 17 illustrates a section of a layered display structure 1 18 provided with an array of V-shaped supports 76, 176 when the layer structure 1 18 is subject to flexing. Even when the display structure is flexed, and although the structural supports are caused to deform as the structure flexes, the V-shaped nature of the supports ensures that a load-bearing capability is maintained for the layer structure.

Other shapes for the support structures 76, 176 include pillars of circular cross-section, pillars of oval cross-section or pillars of hexagonal cross-section. It is thought that the V-shaped structures of Figures 16 and 17 provide the most advantageous load- bearing properties to counter the stresses induced on flexing. Furthermore, continuous localized stress will deteriorate the pixel or may break the TFT backplane. This takes away localized stresses within the structure to provide more robustness to the structure which tends to pro-long the lifespan of the display.

As an alternative to applying the structural supports 76, 176 through a layering process, such as a 3D printing process, in another embodiment the structural support elements 76 within the member 1 18 may be formed by first depositing a resin layer onto, for example, the array of LCD elements 74 of Figure 12 or the OLED elements 104 of Figure 13 and then etching away the resin so that it does not obscure the transmission of light through the structure when the LCD elements are activated to transmit light, but leaving an array of suitably spaced structural supports to give mechanical strength to the member 1 18.

In other embodiments the structural supports may be formed from a conductive material to provide a conductive path to the various elements of the layers. For example, if the layered structure has a touch-screen capability (e.g. capacitive elements), the support elements may provide a conductive path between the user- interaction layer and the elements to enable user control of the structure.

In some embodiments conductive bolsters may be built into or embedded within the polarising layer, for example.

Across the two dimensional surface of the array, bolsters of two different types may be provided; one type in a longitudinal configuration across the surface and one type in a lateral configuration across the surface. In onedirection the bolsters may be electrically insulating and can thus extend through all the layers. It is possible to configure insulating bolsters in this way as it does not result in the leakage of current to display elements such as the OLED, even if the bolsters pass through all of the layers. In the other direction the bolsters may be conductive, e.g. built from the polarising layer, but in which case they cannot extend vertically through all of the layers otherwise some of the OLED elements, for example, would have an unwanted current path to them.

The configuration of the layered structure 1 18, 218 of Figure 12 or Figure 13 is particularly beneficial because it provides extra robustness to the assembly through the use of the array of mechanically stable supports or bolsters 76 distributed throughout the printed electronics layers. This provides benefits not only for the robustness of the final control unit product when in use, but it helps to withstand the high temperatures, and particularly pressures, that are experienced during the injection moulding process during manufacture. Despite the robustness provided by the supports or pillars 76, the overall structure may still retain a degree of flexibility or pliability when it its final form so as to enable its shape to be adapted, depending on the usage requirements, as discussed previously.

One benefit of the embodiments described previously, in particular in relation to Figures 12 to 17, is that the display electronics layer structure lends itself to being formed by means of a roll-to-roll printing process. Figure 18 shows a manufacturing assembly which may be used to produce, for example, a display unit comprising the layered structure 218 of Figure 13.

The assembly includes a conveyor system 130 which allows various layers of the display material to be applied to a substrate in an efficient and convenient manner suitable for high volume production. Initially, a substrate layer 100, which takes the form of a plastic sheet, is wound on an input reel 131 and, by means of a drive apparatus, is pulled along a conveyer towards a first station 132. The substrate 100 is conveyed and held taut by a suitable roller and tensioning apparatus (two of which are identified at 134) in a conventional manner.

At the first station 132, a layer of TFT elements are deposited onto the substrate 100 to form the TFT layer 102, together with the requisite support structures 176 interspersed between the TFT elements. For this purpose the first station 132 may therefore take the form of a 3D printing station for depositing the TFT layer and the material of the supports 176, as described previously in relation to Figure 13. Following the first station, the substrate 100 carrying the TFT layer 102 is then passed through a subsequent, first curing station 136 which serves to cure the materials of the TFT layer and the integrated support structures 176.

Subsequent to the first curing station 136, the substrate 100 is then conveyed to a subsequent, second station 138 where a layer of OLED material is deposited onto the cured TFT layer, together with the requisite support structures 176 for the OLED layer. The precise distribution of the support structures through the various layers of display elements is important to ensure that the support structures 76 align through the layers, as illustrated in Figure 13.

A second curing station 140 follows the second station 138 for curing the OLED elements and the support structures 176 for the OLED layer. At a subsequent third station 142, a layer of polariser 106 is applied to the OLED layer to complete the layered display structure of Figure 13.

Once the layer structure 218 has been formed it may be rolled onto an output roller 144 located at the end of the conveyor system 130, where it can be manuouevred for subsequent processing steps. For example, the layer structure can then be incorporated within a display apparatus by using steps described previously i.e. to provide an injection moulded layer over the display electronics 218.

One benefit of this configuration is that the layer structure is flexible, even when an injection moulded layer is applied to encapsulate the layered structure 1 18, 218. The layered structure can also be made very thin (typically between 1 mm and 0.5 cm), whilst retaining robustness due to the structural supports distributed through the layers.

In another embodiment, the roll-to-roll process may be expanded to produce a structure in which multiple layers of display electronics are assembled together to provide a more sophisticated display. For example, if it is desired to provide multiple layered structures 218 within a single display unit, the layered structure which is wound onto the output roller may then be wound onto the input roller again to repeat the process. In a further embodiment of the invention, the display unit may be assembled using the manufacturing apparatus in Figure 19. In this arrangement the apparatus includes two conveyor systems 130a, 130b, each for producing a layered display structure which is then assembled together with another layered display structure, produced on the other conveyor, to provide a combined structure. The manufacturing apparatus includes a first conveyor system130a on one side of the apparatus and a second conveyor system 130b on the other side of the apparatus. The first conveyor system 130a includes three different statations, similar to those described previously, for applying various layers of display elements and structural supports to a substrate as described previously. A first substraste 200 is wound on a first reel 131 and is driven through the first conveyor system 130a by the drive system, guided by the rollers and tensioning system, so that the substrate is initially deposited with a first layer of display material. A 3D printing station is included within the first station 132 for the purpose of applying a layer of structural supports. Subsequently, the subtrate with the first layer of display elements and the structural supports is conveyed to a second station 138 for depositing a second layer of display material (and structural supports), following by a subsequent curing station 140 for the second layer. The rollers need not incorporate a tensioning means, in which case a single roller may be provided at each roller site.

The second conveyor system 130b operates in a similar manner so that two layers of display elements, together with the requisite support structures, are deposited on the second substrate, and then cured.

Central to the apparatus is a combining station 150 where the two substrates, together with the display layers, are brought together to form a combined structure with one substrate defining one side of the combination and the other substrate defining the other side of the combination, with the display elements layered on the substrates facing inwards towards one another. Such a combination of display layers is capable of providing a multi-functional display which has high versatility and numerous applications.

An example of one such combined display structure is shown in Figure 20. A first substrate (which is wound on the first reel of the first conveyor system 130a) takes the form of a flexible, polarising substrate 200. An outward surface of the substrate defines the A surface of the final display unit with which the user interacts e.g. by viewing and/or touch. The second layer of the structure is a capacitive layer 202 which is applied at the first station 132 of the first conveyor system in Figure 19. The third layer 204 includes a series of structural supports 206, as described previously, which are separated by air gaps 208 dispersed at regular locations throughout the third layer. The structural supports 206 may be deposited in the second station 138 through a 3D printing process. The structural supports are then cured at a 140 curing station which follows the second station 138.

Referring also to Figure 19, on the other side of the display unit, the substrate takes the form of a flexible subtrate 210 which is initially wound on the second reel 152 of the second conveyor system 130b. The substrate is passed to a first station 154 of the second conveyor system 130b and a layer of TFT 212 is applied to the substrate 210, together with a series of structural supports 214. The substrate, together with the TFT layer and the structural supports, is then passed to a curing station 156 which follows the first station 154 for curing the elements carried by the second substrate 210. The substrate is then passed to the second station 158 of the second conveyor system 130b where a layer 215 of OLED material is applied, interspersed with a series of structural supports 216 . A further curing station 160 follows the second station 158 for curing the elements of the OLED layer 215 and the structural supports 216.

The side of the second substrate which faces away from the dsiplay layers defines the B-surface for the final display unit, which is hidden from view when in use.

The two substrates 200, 210, together with the display elements that they carry, are brought together in the combining station 150 with a bonding layer applied between the upper surface of the supports of the gap layer of the first substrate 200 and the upper surface of the OLED layer 215 of the second substrate 210, with the structural supports in each of the facing layers being aligne vertically. The bonding layer is therefore applied intermediate the two structures on either side of the centre line marked as A-A.

The capacitive layer of the layered structure provides a touch-sensitive functionality for the electronic components which is operable by means of the user applying pressure to the A-surface. Although only a cross section of the structure is shown in Figure 18, it will be apprdciated that the display elements (e.g. TFT, OLED) are applied in a two- dimensional matrix to cover the surface area of the structure.

In an alternative embodiment to that shown and described in relation to Figure 18, the layer of TFT elements (active matrix) may be replaced with any other layer of switchable display elements, such as a passive matrix.

It will be apprciated that in these embodiments described in relation to Figure 20, there is no moulded layer or laminate layer to combine the two sides of the combined unit together, other than a bonding layer (not shown) intermediate the two structures on either side of the centre line A-A which may be considered to be an encapsulation layer for the display elements.

The process of manufacture is convenient and can be achieved on a commercial scale with minimal cost, to produce high volumes of a display structures at the output from the combining station 150. Various ones of the stations and curing stations can be replaced, as required, to alter the specific nature of the layers of the display structure. For example, the station for depositing the TFT layer could readily be replaced with a station for depositing LCD elements, and vice versa, or additional stations can be added to provide for additional display and/or electronic layers.

In practice the formation of the structural supports 76, 176, 206, 214; 216 may be achieved by building up the supports, layer on layer, in a two dimensional array as the other layers of material (LCD, OLED etc) are formed on the substrate, rather than by providing separate support structures in each layer which then need to align vertically. This process is particularly beneficial if supports formed from different materials are required. For example, if supports of electrically conducting material are required to provide a conduction path from the A surface to certain elements of the control unit, it is also necessary to provide insulating supports within the array, at appropriate locations, to ensure that there is no conduction to the OLED layer (e.g. layer 215 in Figure 20). Both insulating and conducting supports can be formed by providing different inks at different locations within a two-dimensional printing head.

It will be appreciated that many modifications may be made to the above examples without departing from the scope of the invention as defined in the accompanying claims. By way of example, although embodiments of the invention have been described with reference to a control unit for a vehicle, it will be appreciated that the invention has other applications outside of the automotive sphere. For example, alternatively the invention may be employed in a variety of appliances where there is a need for a user interaction surface and/or a surface where information is displayed to a user (e.g. a control panel on an electrical item). With this in mind, in any of the aforementioned embodiments the A-surface of the control unit need not take the form of a surface with which the user interacts, but may take the form of a surface via which information is displayed or presented to the user of the control unit.