WO2018065604A1

WO2018065604A1 - Control unit

Info

Publication number: WO2018065604A1
Application number: PCT/EP2017/075548
Authority: WO
Inventors: Ashutosh Tomar
Original assignee: Jaguar Land Rover Limited
Priority date: 2016-10-07
Filing date: 2017-10-06
Publication date: 2018-04-12

Abstract

A control unit (10) for an apparatus, the control unit (10) comprising a component-carrying member (18) provided with at last one electronic component (60, 62) configured to provide a function of the apparatus, wherein the component-carrying member is pliable at least during assembly of the control unit; an encapsulation layer (22) encapsulating at least a part of the at least one electronic component; and a thermally conductive element (70) encapsulated at least partially within the encapsulation layer and configured to conduct heat to or away from the at least one electronic component.

Description

CONTROL UNIT

TECHNICAL FIELD The present disclosure relates to a control unit for an apparatus. In particular, but not exclusively, the invention relates to a control unit including electronic components and/or microprocessors relating to operation of the apparatus. The control unit has particular but not exclusive application in a vehicle. Aspects of the invention relate to a control unit, an apparatus, a method of manufacture and a vehicle.

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.

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. A further challenge with control units in vehicles is that heat can build up within the control unit during operation of the electronic components. 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 control unit for an apparatus, an apparatus and a vehicle as claimed in the appended claims.

According to one aspect of the invention, there is provided a control unit for an apparatus, the control unit comprising a component-carrying member provided with at least one electronic component configured to provide a function of the apparatus, wherein the component-carrying member is formed of a material that is pliable or flexible at least during assembly of the control unit; an encapsulation layer encapsulating at least a part of the at least one electronic component; and a thermally conductive element encapsulated at least partially within the encapsulation layer and configured to conduct heat to or away from the at least one electronic component.

The control unit has particular application in a vehicle, wherein the or each electronic component is configured to provide a function of the vehicle, for example a function in the form of control of the lighting system, the heating system, the entertainment system, the seating system, the airbag system, the sun roof, or the window.

The control unit 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 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. Furthermore, the or each electronic component is protected by the encapsulation layer which encapsulates the fragile and sensitive electronic components and circuitry. A further benefit of the invention is that, because the component-carrying member is formed from a material that is pliable, or flexible, at least during the assembly stage of the control unit, the component-carrying member can be manipulated to adopt a variety of different shapes, depending on the requirements for the final product. For example, the control unit need not be flat and may be shaped to have a curved, undulating or non-planar profile.

Moreover, as part of the manufacturing process, as the encapsulation layer is formed over the component-carrying member, the layer and the 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 encapsulation 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, fully integrated within the materials of the encapsulation 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.

The thermally conductive element may be in contact (e.g. thermal contact) with at least a part of the at least one electronic component.

The use of a thermally conductive element within the control unit provides several advantages. Firstly, during assembly of the control unit, the temperatures associated with the process of creating the encapsulation layer onto the electronic components may cause heat build up in the electronic components, which may otherwise cause damage. However, this heat is conducted away from the components via the thermally conductive element, either to a remote component or to the component-carrying member, or other member, depending on where the thermally conductive element is thermally connected. An injection moulding process may be used to form the encapsulation process and this requires particularly high temperatures to be used. In this way unwanted heat energy from the electronic components may be beneficially used to heat the ambient environment in the vicinity of the control unit. By way of specific example, where the control unit comprises a part of the interior of a vehicle cabin, heat energy may be transferred from the component-carrying member and/or the second member to the cabin environment by thermal radiation or convection. In this manner, localised heating may be provided within the vehicle cabin, thereby reducing the load on the vehicle HVAC system.

By way of example, the remote component may take the form of a part of the injection moulding tooling equipment, or alternatively the thermally conductive element may be in thermal contact with another member of the control unit to conduct heat away from the or each of the electronic components via the other member(s).

A further advantage is that, during use, as electronic components heat up during use, the heat is transferred away from the components via the thermally conductive element.

In one embodiment the component-carrying member may be provided with an additional thermally conductive layer upon which the or each electronic component is carried, to provide enhanced thermal conduction away from the or each component.

A further benefit of the invention is that, because the component-carrying member is formed from a material that is pliable, or flexible, at least during the assembly stage of the control unit, the component-carrying member can be manipulated to adopt a variety of different shapes, depending on the requirements for the final product. For example, due to the pliable nature of the control unit, at least during the manufacturing stages, it can be adapted to a shape suitable for use as a lid of a glove compartment or an overhead control panel, which generally may have a curved surface area. For example, the control unit need not be flat and may be shaped to have a curved, undulating or non-planar profile. Moreover, as part of the manufacturing process, as the injection moulded layer is formed over the component-carrying member, the layer and the 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 encapsulation 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 within the materials of the encapsulation 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. The structural electronics, being moulded in this way, become a part of the load-bearing features for the control unit. In one embodiment, the component-carrying member may be formed from a material that is pliable during the assembly stages, but which then 'sets' or becomes more rigid once the control unit has been assembled so as to define a rigid end product. Alternatively, the material from which the electronic-carrying component may be formed may retain a degree of pliability in its final form, once the control unit is fully assembled, so that the final product is, for example, flexible or bendable.

The invention therefore provides a highly versatile control unit structure which can be adapted for use in a wide range of different applications. For example, due to the pliable nature of the control unit, at least during the manufacturing stages, it can be adapted to a shape suitable for use as a lid of a glove compartment or an overhead control panel, which generally may have a curved surface area.

In other embodiments, the second member may be spaced apart from the component- carrying member by the encapsulation layer to define at least a three-layer structure for the control unit.

For example, the second member may be provided with at least one further electronic component, so that the or each of the electronic components on the component- carrying member and the at least one further electronic component on the second member are sandwiched between the component-carrying member and the second member within the encapsulation layer.

This arrangement provides the advantage that the electronic components are distributed between different surfaces, which may have benefits for space and/or heat generation. The arrangement provides a particular advantage where the control unit is operated by means of gesture control, so that the components operated by gesture control are on the reverse of the A-surface but other components may be displaced from them and carried on the other member.

The thermally conductive element may include a contact region configured to make contact with the component-carrying member and/or the second member to conduct heat to or away from the or each electronic component- via said component-carrying member. For example, in one embodiment the contact region may be configured to make contact with an underside of the component-carrying member to conduct heat to or away from the or each electronic component via the underside of the component- carrying member.

The thermally conductive element may include an extension piece which projects from the element to define the contact region.

The thermally conductive element may be a layer of thermally conductive material laid onto at least a part of the or each electronic component. In one example, the thermally conductive element may comprise an electrically insulating material.

It may be beneficial to provide the control unit with an active heat pump to promote heat transfer to or away from the or each electronic component. The heat pump may take the form of a solid state device, such as a Peltier device.

In one embodiment, the control unit may comprise a user-interaction surface visible to a user of the apparatus, in use. For example, the component-carrying member may define the user-interaction surface. In other embodiments, the user-interaction surface may be a tactile surface with which the user interacts, in addition or alternatively to visual interaction.

The user-interaction surface is configured to receive a user command, and wherein the or each electronic component is operable in response to the user command.

The control unit may comprise a piezoelectric layer adjacent to the user-interaction surface to enable control of the or each electronic component when the user applies a user command in the form of pressure to the user-interaction surface.

The or each electronic component may take the form of a printed electronic circuit carried on a component-carrying surface.

In one embodiment, the component-carrying surface may be on the reverse side of the component-carrying member to the presentation surface. This embodiment provides the advantage that only a single member is required to define both the presentation surface on one side and the printed circuit elements on the other side (i.e. the component-carrying surface). The control unit of this embodiment is particularly thin and lightweight, and can be formed using a single-stage injection moulded process to form the injection moulded layer.

In one embodiment the printed electronic circuit may comprise a plurality of conductive tracks for carrying current to at least one electronic component of the printed electronic circuit.

For example, the conductive tracks may act, together with the user-interaction surface, as electrodes of a capacitor to provide a capacitive touch control functionality in response to the user commands. Capacitive touch control provides a quick, effective and sophisticated feel of control for the user of the control unit.

In some embodiments, a further thermally conductive element may be deposited on the underside of the component-carrying member to further aid the conduction of heat to or away from the at least one electronic component. For example, the further thermally conductive element may take the form of a thermally conductive track on the underside of the component-carrying surface.

The further thermally conductive track may be aligned, as close as possible, with at least one of the electronic components on the opposed surface of the component- carrying member.

It may be beneficial for the further thermally conductive element to have an undulating surface to increase surface area for heat dissipation.

The thermally conductive element may comprise an electrically insulating material, comprising one or more selected from a group comprising: a metamaterial; boron nitride; silicon carbide; silicon nitride; aluminium nitride. Boron nitride has particular benefits.

By way of example, the thermally conductive element may be formed from a material that is a good thermal conductor, and also a good electrical insulator (e.g. a ceramic material). In another embodiment, the thermally conductive element may comprise an electrically conductive material.

In some embodiments, the electrically conductive material may be electrically insulated from the at least one electronic component by electrically insulating material. So, for example, the control unit may comprise a layer of electrically and thermally conducting material upon a layer of electrically insulating material which is applied to the at least one electronic component.

The control unit may comprise at least one active electronic component on the printed electronic circuit and/or at least one passive electronic component on the printed electronic circuit.

It may be beneficial if the thermally conductive element is in thermal contact only with active components of the printed electronic circuit. The encapsulation layer may be an injection moulded layer or a lamination layer, such as a glue layer. According to another aspect of the invention there is provided a control unit of the aforementioned type, configured for use in a vehicle.

According to another aspect of the invention, there is provided a vehicle comprising the control unit of a previous aspect of the invention.

According to another aspect of the invention there is provided a method of assembling a control unit for an apparatus, the method comprising providing, on a component- carrying member, at least one electronic component configured to provide a function of the apparatus, in use; encapsulating at least a part of the at least one electronic component within an encapsulation layer; and bringing a thermally conductive element into thermal contact with the at least one electronic component during the encapsulation so as to conduct heat to or away from the at least one electronic component during assembly of the control unit. The method may, in one embodiment, include encapsulating the or each electronic component using an encapsulation apparatus, and wherein the thermally conductive element forms a part of the encapsulation apparatus. The encapsulation apparatus may be an injection moulding apparatus for injection moulding the encapsulation layer, or it may be a lamination apparatus for providing a laminated layer of encapsulation.

In one embodiment, therefore, the thermally conductive element does not form a part of the final assembled control unit. Alternatively, the method may comprise encapsulating the or each electronic component together with the thermally conductive element, at least in part, so that the thermally conductive element forms a part of the assembled control unit.

The method may comprise printing (e.g. by a screen printing method) the thermally conductive element onto the at least one electronic component. The method may comprise applying a mask to the component carrying member so that areas are exposed only where the or each electronic component is provided and applying a layer of thermally conductive material to the mask so that thermally conductive material is only applied to the electronic component and not to a remainder of the surface of the component-carrying member.

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 schematic cross section of another control unit, formed using a single shot injection moulding process;

Figure 1 1 is a perspective view of a control unit with only partial encapsulation of the printed electronics layer;

Figure 12 is a schematic cross section of a control unit of an embodiment of the invention, comprising a heat transfer arrangement; Figure 13 is a schematic view cross section of a control unit of an alternative embodiment with a different heat transfer arrangement to that shown in Figure 12;

Figure 14 is a schematic view of a rear surface of a control unit, such as that shown in Figure 5, to show a thermally conducting feature of the control unit;

Figure 15 is a schematic cross section of a control unit of a further embodiment, in which the profile of the control unit is curved; Figure 16 is a schematic perspective view of a control unit formed by a lamination process;

Figure 17 is a schematic cross section of a printed electronics layer which may be used in embodiments of the invention;

Figure 18 is a perspective view of a portion of the printed electronics layer in Figure 17 to show a support structure thereof; and Figure 19 is a perspective view of a portion of a printed electronics layer to show an alternative support structure for the printed electronics layer to that shown in Figure 18.

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, 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 10 of the invention 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 control unit in the form of a presentation surface 16 (which the user interacts with by viewing), 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 user may also interact with the presentation surface by means of touch.

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 1 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 component upon which the electronic components and/or circuitry is printed). 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 layers, and even flexible layers, as discussed in further detail below. The first and second members 14, 18 are pre-formed members. The pre-formed first and second members 14, 18 are placed in the injection mould prior to the injection moulding process which produces the control unit 10 by forming layer 22.

Referring to Figure 4, 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 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, formed in the same way as described previously for the first member, to which a plurality of active and passive electronic components and printed tracks or wires are applied 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, flexographic 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. In the present embodiment the first and second members 14, 18 are generally planar with a slight curvature on their upper surfaces. In other embodiments, for example, 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 embodiments of the invention 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.

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. The B-surface 20 is provided with a printed electronics layer (29 - 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 embodiments 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 control units (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 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 control units which may be formed using a twin shot (2K) injection moulding method. Figure 8 is similar to 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 embodiment. 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 an alternative control unit 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 control units (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 is a further alternative embodiment of the invention in which both the first and second members 14, 18 are provided with electronic components, identified as 30, together with the necessary conductive tracks 38. As mentioned previously the first member 14 may be provided with a protective coating 50, although this is not essential. This embodiment may be particularly useful for a control unit which is configured for gesture control, wherein the electronic components need to be located close to the A surface of the control unit but other electronic components may be located on the B surface of the control unit. For example, it may be that one surface of the control unit is not of sufficient area to accommodate all the necessary electronic components, or alternatively it may be beneficial to spread the distribution of the electronic components, for example to minimize local heat generation from the components, in use.

The embodiment shown in Figure 10 may be provided with a connector (not shown) which is configured to apply the required currents to the electronic components. It may be desirable to control the electronic components on each of the members 14, 18 using a common connector, as opposed to individual connectors being used for each one. Figure 1 1 shows another control unit 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 prints 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.

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.

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 of the invention may be employed to avoid the aforementioned problems altogether.

In order to provide additional protection for the more thermally sensitive electronic components it may be beneficial to incorporate a heat-transfer arrangement into the control unit to transfer heat that builds up during the injection moulding process away from the sensitive components. The provision of a heat- transfer arrangement also has benefits in operation of the control unit as it allows heat that is generated in use to be dissipated away from the areas of the control unit which may be damaged or caused to malfunction in the event of overheating. Any of the previously-described control units may be provided with a heat transfer feature, in the form of a thermally conductive element, and embodiments of the invention in which a heat transfer feature is included will now be described. Figure 12 shows an embodiment of the control unit 10 which is similar to Figure 8 in that it includes a first member 14 which defines an A-surface 16 of the control unit, such as a presentation surface to the user with which the user interacts visually, and a second member 18 which defines a B-surface 20 upon which various electronic components 60, 62 are mounted. In the example shown the B-surface is provided with three electronic components 60 which are sensitive to overheating, and one component 62 which is less sensitive to overheating. Conductive tracks (not identified), as described previously, are also provided on the second member 18 to provide current to the electronic components 60, 62.

A heat-transfer arrangement 70 in the form of a thermally conductive layer is provided to make contact with the three heat-sensitive electronic components 60. The thermally conductive layer 70 includes a main body region 70a which overlays the electronic components 60, making thermal contact therewith, and a thermal contact region defined by an extension region 70b which projects from the main body region 70a at one end to make contact with one end of the second member 18. The conductive layer may conveniently be applied to the electronic components by means of a screen printing method. During manufacture, a mask may be applied to the electrically conducting tracks and electronic components, with the mask being configured to expose only those areas where heat is required to be extracted from. In this way, thermally conducting material is only printed on the areas exposed by the mask so that a reduced amount of conducting material is required, compared to the amount of material required if no mask is used, thus providing a cost benefit. Heat that builds up in the electronic components 60 is transferred, via the thermally conducting layer 70, to the second member 18 so that, by thermal conduction, heat is dissipated away from the components 60. If any of the electronic components is less susceptible to high temperatures, such as the component labelled 62, the thermally conducting layer 70 need not extend to that component, as shown in Figure 12. The heat transfer arrangement 70 may also include an additional layer 71 , adjacent to the second member 18 to which the electronic components 60 are thermally connected, to provide an enhanced heat transfer function. Heat transfer enhancement comes from the fact that the additional layer 71 provides another route for heat transfer away from the electronic components 60 to the second member 18. Heat dissipation away from the electronic components 60 via the thermally conductive layer 70 occurs during the injection moulding process when the temperatures around the components are especially high, but heat transfer also continues during use of the control unit 10 when the electronic components may also heat up. The provision of the thermally conductive layer heat transfer is therefore advantageous in manufacture of the control unit, and during its use.

The material of the thermally conductive layer may be a two-dimensional heat conducting layer covering the surface of the underlying layer or a meta material with high thermal and low electrical conductivity. For example, the layer may be formed from phyllosilicates or a mica sheet. Other suitable materials are insulators (low electrical conductivity) where atomic vibrations (phonons) are very efficient at transporting heat. Often, high phonon thermal conductivity occurs in materials with light elements (especially, B, C, N, O), because heat is mostly transported by acoustic phonons whose group velocity (the speed of sound in the material) is inversely proportional to atomic mass. Examples of materials with high thermal conductivity and low electrical conductivity are certain metamaterials and polymorphs of boron nitride, silicon carbide, silicon nitride, and aluminium nitride. In a modification to that shown in Figure 12, a further layer of thermally conductive material (not shown) may be applied to the extraction point from the thermally conducting layer 70 to provide a larger surface area from where heat is dissipated from the assembly. Alternatively, a Peltier device may be provided at the extraction point to maximise heat transfer away. This material may be the same material from which the thermally conductive layer 70 is formed, or may take the form of any of the materials mentioned above. The shape of the material may be selected so as to optimise the heat dissipation. For example, this material may include a brush finish surface and/or grooves to increase heat dissipation. In a further embodiment (not shown), the second member 18 may itself form a thermally conducting layer to provide a large surface area for the extraction of heat from the electronic components. In this case, however, a layer 71 a of electrically insulating material (such as boron nitride) is printed onto the reverse side of the additional layer 71 to that carrying the electronic components, to prevent electronical conduction directly to the second member 18.

It is also envisaged that the heat conducting material from which the layer 70 is formed may be electrically conducting, as well as thermally conducting. A material such as graphene is suitable for this purpose. In this case, however, it is necessary to ensure that there is no electrical conduction between the electronic components and the heat conducting layer so that it is necessary to provide an electrically insulating 'mask' for the electronic components. For such embodiments it may be necessary to create two masks for the manufacturing process, one for the application of the thermally conducting layer and the other for the application of the electrically insulating layer, with the masks configured so that the insulating material is disposed between the electronic components and the thermally conducting material to prevent the aforementioned electrical conduction but to allow the desired heat conduction.

Because this embodiment requires the use of multiple layers, which adds cost and weight to the device, it may be beneficial to use a heat conducting material that is electrically insulating (e.g. boron nitride). Figure 13 shows an alternative embodiment of the control unit 10 provided with a heat- transfer arrangement. In this embodiment the electronic components 60 are provided on the reverse of the first member 14 (i.e. on the opposed surface to the A-surface 16) and the second member 18 provides structural support for the control unit 10. As described previously for the embodiment in Figure 12, a main body region 70a of a thermally conductive layer 70 is overlaid onto the three electronic components 60 which are most susceptible to damage or malfunction in the event of overheating. An extension region 70b of the layer 70 projects substantially perpendicularly from the main body region 70a to define the thermal contact region and to intercept the second member 18 at the rear of the control unit 10. As before, heat from the electronic components 60 is transferred via the layer 70 to the second member 18 so as to protect the components from damage and/or malfunction due to overheating, either in manufacture or during use. A further alternative embodiment (not shown) makes use of a heat-transfer feature which does not form a part of the final control unit structure, as in Figures 12 and 13, but instead forms a part of the manufacturing tool used for the injection moulding process. This provides protection from heat for the electronic components during manufacture only.

In a still further embodiment (not shown) in which a heat transfer arrangement is employed, a Peltier heat pump or a loop heat pipe may be used in combination with the thermally conductive element so as to provide a means of active control of heating or cooling of the encapsulated electronic circuit. A Peltier heat pump, or thermoelectric heat pump as it is sometimes known, is a solid-state, active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. The heat pump can be used either for heating or for cooling. It can also be used as a temperature controller that either heats or cools.

In other embodiments it is envisaged that the thermally conductive heat transfer arrangement may be configured to conduct heat to the printed electronic circuit, for example, if there are other features of the control unit require heat to be transferred to them. It may be particularly beneficial for use in vehicles in cold climate countries where very low temperatures can be a problem especially as the vehicle is started. The heat transfer arrangement need not take the form of a 'heat-sink' arrangement, but may be provided for the purpose of heat transfer to various ones of the electronic components. Some embodiments it may be that heat that is transferred away from some electronic components can be transferred to others where heat build up is required.

Another embodiment is shown in Figure 14 which shows a rear surface 100 of a second member 18 of a control unit, such as that shown in Figure 4. The second member 18 carries at least one electronic component on its front surface (identified by dashed lines as reference number 160) as described previously. For example, one of the electronic components may be an LED 160. A current is supplied to the LED 160, in use, via a conductive track (not shown) and so the LED 160 tends to generate heat in operation. The rear surface 100 of the second member 18 may be provided with a deposit 102 of thermally conducting material, such as aluminium, at a position which aligns with the position of the LED component 160 on the opposed surface, In this way, heat generated within the LED is conducted away from the control unit, through the second member 18 and the aluminium deposit 102. Forming the aluminium deposit 102 with a relatively large area ensures effective heat conduction away from the LED.

As an alternative approach, or in addition, a thermally conductive track 161 may be applied to the rear surface 100 of the second member 18 to align with the positioning of the electronic components (identified by reference numbers 162) arranged on the opposed front surface of the second member. The thermally conductive track may follow a meandering path so as to correspond to the positioning of the electronic components on the front surface of the member 18. This ensures that heat generated in the electronic components is conducted through the second member 18 to the aluminium track. End portions 164 of the track are provided with enlarged deposit of aluminium to disperse heat away from the track. The aluminium track, via the end portions, may then be connected to a radiator device (not shown) to transfer heat away from the control unit entirely. Likewise, the enlarged deposit 102 of aluminium may also be connected to a radiator device for the same purpose. It will be appreciated that the tracks and deposits may take any shape and form, irregular or regular, so as to correspond approximately to the positioning of the heat- generating electronic components on the front surface of the member 18. It is desirable in some cases for the aluminium deposits to be as large as possible to maximise heat dissipation over a large surface area. In order to maximise the surface area of the aluminium deposits still further, grooves or ridges may be formed in the deposits to define an undulating or uneven surface.

Typically, the deposits of thermally conductive material may be applied by screen printing methods.

It will be appreciated from the foregoing description that the invention provides a robust, lightweight structure for the control unit 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 embodiment is the overhead control panel described previously and as shown in Figure 4. 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, 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 another embodiment (not shown), the control unit forms a part of a vehicle sun- visor. Typically, the sun-visor in a vehicle takes the form of a pull-down flap which obscures a region of the windscreen when in its pulled-down configuration so as to reduce glare for the user, but can be stowed in an upper substantially horizontal configuration, resting against the top of the windscreen frame, when not in use. Conventional sun visors are often provided with a vanity mirror and a light source which illuminates the area around the mirror and the user's face when the sun visor is pulled down. The light source is either operable by a switch on the sun visor or may light up automatically as the visor is pulled down. In the present invention the control unit may be mounted on the sun visor so that the electronic components (whether mounted on the reverse of the A-surface or on a B-surface) are packaged conveniently within the sun visor unit to provide enhanced functionality for the lighting. By way of example, the level of lighting provided by the light source may be controlled in dependence on ambient lighting levels, or the timing of illumination from the light source may be controlled in dependence on other vehicle parameters or operating modes. The invention therefore enables an integrated light emitting system to be provided in the small confines of a vehicle sun visor to give improved lighting features.

In other 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, rather than providing an interaction surface for 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.

The previously described embodiments of the invention are formed using an injection moulding process to produce the intermediate layer of the control unit. 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 16 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 16). 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.

In a still further embodiment (not shown) 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 pre-form.

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.

Figure 17 shows one possible configuration of the second member 1 18 which may be used to form a part of the control unit 10 in the previous embodiment where the control unit 10 takes the form of a display unit. The configuration shown in Figure 17 is a laminated structure which is formed by layering different materials and electronic components onto a base layer (backlight layer 73) to achieve the desired lighting function. Display elements are deposited onto the backlight layer 73 which provides a supporting structure to the second member 1 18 and provides a source of 'backlight' illumination for the components laid on top. A first polarising layer 72 is then laid onto the backlight layer 73 and an array of Liquid Crystal Display (LCD) elements 74 is then laid onto the first polarising layer 72. The LCD elements 74 may be deposited in the form of an ink and are interspersed with structural supports 76, with one support 76 being located between adjacent LCD elements. A transistor layer 78 is laid over the LCD elements 74 and 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. An array of colour filter elements 80, typically RGB filter elements, is laid onto the transistor layer 78. The colour filter elements 80 are interspersed with further structural supports 82 in the same was as for the LCD elements 74. 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 in the form of a thermally conducting layer (not shown) and optionally an active heat transfer component 88, such as that described previously, may be incorporated into the laminated structure also. 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. 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 other embodiments different materials with different properties may be deposited to form the printed electronics layer. For example, inks having conductive, resistive, and semi conductive properties may be deposited on the component-carrying surface to form the printed electronic circuit, depending on the required functionality. Figure 18 shows the array of support elements 76 formed using a 3D printing process, as described previously, whereas in Figure 19 the structural support elements 76 are formed using a screen printing process. The supports 76 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 LCD elements 74 are operated in a manner known in the art by applying a voltage to the transistor layer 78 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.

In another embodiment (not shown), the structural support elements 76 within the second member 1 18 may be formed by first laying a resin layer onto, for example, the array of LCD elements 74 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 second member 1 18. The embodiment in Figures 17 to 19 has been described in terms of a liquid crystal display, but other types of display may be used in the invention, such as LEDs, OLEDs, AMOLED, quantum dot display electrophoretic and electro wetting displays. The display elements may be formed by using different inks to print different components such as those mentioned above.

If the injection moulding process is used to form the control unit structure as a whole, the configuration of the second member 18 shown in Figure 17 is particularly beneficial because it provides extra rigidity to the second member 18 through the use of an array of mechanically stable supports or pillars 76 distributed throughout the printed electronic layer, which helps to withstand the high temperatures, and particularly pressures, that are experienced during the injection moulding process.

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.

The thermally conductive elements 70 described previously may be incorporated within a control unit as described with reference to any of the previous figures, as defined by the scope of the appended claims.

Claims

1 . A control unit for an apparatus, the control unit comprising:

a component-carrying member provided with at last one electronic component configured to provide a function of the apparatus, wherein the component-carrying member is pliable at least during assembly of the control unit;

an encapsulation layer encapsulating at least a part of the at least one electronic component; and

a thermally conductive element encapsulated at least partially within the encapsulation layer and configured to conduct heat to or away from the at least one electronic component.

2. The control unit as claimed in claim 1 , wherein the thermally conductive element is in thermal contact with the at least one electronic component.

3. The control unit as claimed in claim 2, wherein the thermally conductive element includes a thermal contact region configured to make thermal contact with a remote component during assembly of the control unit, thereby to conduct heat to or away from the at least one electronic component via the remote component.

4. The control unit as claimed in claim 3, wherein the thermally conductive element includes a contact region configured to make thermal contact with another member to conduct heat to or away from the at least one electronic component via the other member.

5. The control unit as claimed in any of claims 1 to 4, wherein the component- carrying member is provided with an additional thermally conductive layer upon which the at least one electronic component is carried. 6. The control unit as claimed in any of claims 1 to 5, comprising a second member spaced apart from the component-carrying member by the encapsulation layer to define at least a three-layer structure for the control unit.

7. The control unit as claimed in claim 6, wherein the second member is provided with at least one further electronic component, so that the or each of the electronic components on the component-carrying member and the at least one further electronic component on the second member are sandwiched between the component-carrying member and the second member within the encapsulation layer.

8. The control unit as claimed in claim 7, wherein the thermally conductive element includes a thermal contact region configured to make thermal contact with the second member to conduct heat to or away from the or each electronic component via the second member.

9. The control unit as claimed in any of claims 1 to 8, wherein the thermally conductive element includes a thermal contact region configured to make thermal contact with an underside of the component-carrying member to conduct heat to or away from the at least one electronic component via the underside of the component- carrying member.

10. The control unit as claimed in claim 9, wherein a further thermally conductive element is deposited on the underside of the component-carrying member to further aid the conduction of heat to or away from the at least one electronic component.

1 1 . The control unit as claims in claim 10, wherein the further thermally conductive element takes the form of a thermally conductive track on the underside of the component-carrying surface.

12. The control unit as claimed in claim 1 1 , wherein the further thermally conductive track is aligned with at least one of the electronic components on the opposed surface of the component-carrying member. 13. The control unit as claimed in any of claims 10 to 12, wherein the further thermally conductive element has an undulating surface to increase surface area for heat dissipation.

14. The control unit as claimed in any of claims 9 to 13, wherein the thermally conductive element includes an extension piece which projects from the thermally conductive element to define the thermal contact region. 15. The control unit as claimed in any of claims 1 to 14, wherein the thermally conductive element is a layer of thermally conductive material laid onto at least a part of the at least one electronic component.

16. The control unit as claimed in any one of claims 1 to 15, wherein the thermally conductive element comprises an electrically insulating material.

17. The control unit as claimed in claim 16, wherein the thermally conductive element comprises one or more selected from a group comprising: a metamaterial; boron nitride; silicon carbide; silicon nitride; aluminium nitride.

18. The control unit as claimed in any of claims 1 to 15, wherein the thermally conductive element comprises an electrically conductive material.

19. The control unit as claimed in claim 18, wherein the electrically conductive material is electrically insulated from the at least one electronic component by electrically insulating material.

20. The control unit as claimed in claim 19, comprising a layer of electrically and thermally conducting material upon a layer of electrically insulating material which is applied to the at least one electronic component.

21 . The control unit as claimed in any of claims 1 to 20, comprising an active heat pump to promote heat transfer to or away from the at least one electronic component. 22. The control unit as claimed in claim 21 , wherein the heat pump is a solid state device.

The control unit as claimed in claim 21 or claim 22, wherein the heat pump is a r device.

24. The control unit as claimed in any of claims 1 to 23, comprising a user- interaction surface visible to a user of the apparatus, in use. 25. The control unit as claimed in claim 24, wherein the component-carrying member defines the user-interaction surface.

26. The control unit as claimed in claim 24 or claim 25, wherein the user-interaction surface is configured to receive a user command, and wherein the at least one electronic component is operable in response to the user command.

27. The control unit as claimed in claim 26, comprising a piezoelectric layer adjacent to the user-interaction surface to enable control of the printed electronic circuit when the user applies a user command in the form of pressure to the user- interaction surface.

28. The control unit as claimed in claim 26 or claim 27, wherein the at least one electronic component is carried on a component-carrying surface, and wherein the component-carrying surface is on the reverse side of the component-carrying member to the user-interaction surface.

29. The control unit as claimed in any of claims 24 to 28, wherein the at least one electronic component forms a part of a printed electronic circuit comprising a plurality of conductive tracks for carrying current to the at least one electronic component of the printed electronic circuit.

30. The control unit as claimed in claim 29, wherein the conductive tracks act, together with the user-interaction surface, as electrodes of a capacitor to provide a capacitive touch control functionality in response to the user commands.

31 . The control unit as claimed in any of claims 1 to 30, comprising at least one active electronic component.

32. The control unit as claimed in any of claims 1 to 31 , comprising at least one passive electronic component.

33. The control unit as claimed in claim 31 or claim 32, wherein the thermally conductive element is in thermal contact only with one or more active electronic components.

34. The control unit as claimed in any of claims 1 to 33, wherein the encapsulation layer is an injection moulded layer.

35. The control unit as claimed in any of claims 1 to 34, wherein the encapsulation layer is a lamination layer.

36. The control unit as claimed in any of claims 1 to 35, configured for use in a vehicle.

37. The control unit as claimed in claim 36, wherein the at least one electronic component is configured to control one or more of the following vehicle functions; an airbag, an entertainment system, a sound system, a window, a seating system, a lighting system.

38. A vehicle comprising the control unit as claimed in any of claims 1 to 37.

39. A method of assembling a control unit for an apparatus, the method comprising:

providing, on a pliable component-carrying member, at least one electronic component configured to provide a function of the apparatus, in use

encapsulating at least a part of the at least one electronic component within an encapsulation layer; and

bringing a thermally conductive element into thermal contact with the at least one electronic component during the encapsulation so as to conduct heat to or away from the at least one electronic component during assembly.

40. The method as claimed in claim 39, comprising encapsulating the at least one electronic component using an encapsulation apparatus, and wherein the thermally conductive element forms a part of the encapsulation apparatus. 41 . The method as claimed in claim 40, wherein the thermally conductive element does not form a part of the final assembled control unit.

42. The method as claimed in claim 41 , comprising encapsulating the at least one electronic component together with the thermally conductive element, at least in part, so that the thermally conductive element forms a part of the assembled control unit.

43. The method as claimed in any of claims 39 to 42, comprising printing the thermally conductive element onto the at least one electronic component. 44. The method as claimed in claim 43, comprising applying a mask to the component carrying member so that areas are exposed only where the or each electronic component is provided and applying a layer of thermally conductive material to the mask so that thermally conductive material is only applied to the electronic component and not to a remainder of the surface of the component-carrying member.