GB2554737A

GB2554737A - Control unit

Info

Publication number: GB2554737A
Application number: GB1617061.5A
Authority: GB
Inventors: Tomar Ashutosh
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2016-10-07
Filing date: 2016-10-07
Publication date: 2018-04-11
Also published as: GB201617061D0

Abstract

A control unit 10 and method of assembling for an apparatus which may be a vehicle, the control unit 10 comprising a circuit-carrying member 18 with a PCB and laminate encapsulation layer 22 encapsulating at least part of the PCB. The PCB is laminated using a pliable laminate to form the laminate encapsulation layer 22. A second member 14 may be spaced apart from the circuit-carrying member 18 by the laminate encapsulation 22 to define a three layer structure. A presentation surface 16 may define a user interaction surface to enable control of the PCB when the user applies a command. The presentation surface 16 may be provided with at least one graphical feature 24. The control unit 10 may comprise a thermally conductive element applied to the PCB to conduct heat away from the PCB which may also comprise an extension piece projecting away from the circuit-carrying member 18.

Description

(54) Title of the Invention: Control unit Abstract Title: CONTROL UNIT (57) A control unit 10 and method of assembling for an apparatus which may be a vehicle, the control unit 10 comprising a circuit-carrying member 18 with a PCB and laminate encapsulation layer 22 encapsulating at least part of the PCB. The PCB is laminated using a pliable laminate to form the laminate encapsulation layer 22. A second member 14 may be spaced apart from the circuit-carrying member 18 by the laminate encapsulation 22 to define a three layer structure. A presentation surface 16 may define a user interaction surface to enable control of the PCB when the user applies a command. The presentation surface 16 may be provided with at least one graphical feature 24. The control unit 10 may comprise a thermally conductive element applied to the PCB to conduct heat away from the PCB which may also comprise an extension piece projecting away from the circuit-carrying member 18.

FIGURE 2

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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 and a method of assembly.

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.

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, a method of manufacture and a vehicle as claimed in the appended claims.

According to one aspect of the present invention there is provided a control unit for an apparatus, the control unit comprising a circuit-carrying member provided with a printed electronic circuit configured to provide a function of the apparatus; and a laminate encapsulation layer encapsulating at least a part of the printed electronic circuit.

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 in the apparatus in which it is used.

According to one aspect of the invention in particular, there is provided a control unit for a vehicle, the control unit comprising a circuit-carrying member provided with a printed electronic circuit configured to provide a function of the vehicle; and a laminate encapsulation layer encapsulating at least a part of the printed electronic circuit.

The control unit has particular application in a vehicle, wherein the printed electronic circuit 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.

Other embodiments envisage that the control unit forms 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 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 printed electronic circuit is protected by the laminate encapsulation layer which encapsulates the fragile and sensitive electronic components and circuitry. The user command may be the pressing of a button, a capacitive touch command such as a touch or swipe with a finger, a gesture or a voice activation command received by a microphone. The vehicle function may be a control signal to a component of the printed electronic circuit, such as the switching on of a light.

In one embodiment, the control unit comprises a presentation surface visible to a user of the apparatus, in use.

In one embodiment the circuit-carrying member defines the presentation surface.

In another embodiment the presentation surface defines a user-interaction surface for receiving a user command, and wherein the printed electronic circuit is operable in response to the user command.

It may be advantageous to include 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, thereby to control the printed electronic circuit.

The control unit may comprise a component-carrying surface which carries at least one electronic component of the printed electronic circuit.

For example, in one embodiment, the component-carrying surface may be on the reverse side of the circuit-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 convenient lamination process to provide the laminate encapsulation layer.

The control unit may comprise a second member spaced from the circuit-carrying member by the laminate encapsulation layer to define a three-layer structure for the control unit.

The second member may define the presentation surface.

The circuit-carrying member and/or the second member may take the form of a preformed layer i.e. a layer that is formed prior to a step taken to forming the laminate encapsulation layer using the lamination process. The circuit-carrying member and/or the second member may also be laminate layers.

The three part structure of the circuit-carrying member, the second member, and the laminate encapsulation layer between, is particularly suitable where there is a need for an A-surface with which the user interacts at the front of the control unit, and a Bsurface at the rear of the control unit which carries the printed electronic circuit.

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

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 command.

Capacitive touch control provides a quick, effective and sophisticated feel of control for the user of the control unit.

In one embodiment, a greater number of conductive tracks may be provided on the printed electronic circuit than is required to provide adequate current to electronic components of the printed electronic circuit, thereby to provide track redundancy in the event of breakage and/or failure of one or more of the conductive tracks.

The benefit of providing track redundancy in this way is that any track breakage or malfunction may be compensated for by the provision of additional tracks which still provide enable the necessary current to be applied to the electronic components of the circuit, in use.

The control unit may comprise an additional layer provided on the presentation surface to provide an aesthetic finish to the control unit.

The additional layer may be a veneer which complements a surface of the apparatus in which the control unit is used, for example an interior trim of a vehicle if the control unit forms a control unit for a vehicle. By complements it is intended to mean that the veneer may match or otherwise correspond in a complementary manner to the rest of the interior of the vehicle in which the control unit is installed. The veneer may be a wood finish, a plastic finish, a leather effect finish, or any other finish that is commonly found, for example, inside a vehicle cabin.

The additional layer may be a protective coating.

For example, the additional layer may be an injection moulded layer or another laminate layer.

The additional layer may be provided with one or more cut outs to enable enhanced depth effects to be achieved when the user views the additional layer through the cut outs (e.g. if the cut outs have different depths).

The control unit may comprise a thermally conductive element encapsulated at least partially within the laminate encapsulation layer and configured to conduct heat to or away from the printed electronic circuit.

The use of a thermally conductive element within the control unit provides several advantages. Firstly, during assembly of the control unit, heat associated with the lamination process may cause heat build up in the printed electronic circuit, which may otherwise cause damage to the circuit. Heat is conducted away from the circuit, either to a remote component or to the circuit-carrying and/or second member, depending on where the thermally conductive element is disposed or thermally contacted. The remote component may take the form of a part of tooling equipment for the lamination process, for example, or alternatively the thermally conductive layer may be in thermal contact with the circuit-carrying member and/or second member and conduct heat via these members. Secondly, during use, as components of the printed electronic circuit heat up during use, the heat is transferred away from the circuit via the thermally conductive element.

In this way unwanted heat energy from the printed electronic circuit 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 circuit-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.

The circuit-carrying member and/or the second member may comprise a pre-formed layer i.e. a layer that is formed prior to the formation of the laminate encapsulation layer. For example, the laminate encapsulation layer may be formed from a glue or other material which is pliable when heated, and less pliable or sets rigidly when cooled.

The circuit-carrying member may be provided with a plurality of structural supports to enhance rigidity of the control unit. In one embodiment, the printed electronic circuit may comprise a plurality of electronic components, and wherein the structural supports are interspersed between the electronic components.

The use of structural supports provides a degree of rigidity to the control unit which may be useful, especially if the circuit-carrying member is a relatively thin layer or laminate substrate.

If the control unit forms a control unit for a vehicle, the control unit may comprise at least one electronic component 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.

According to another aspect of the invention, there is provided an apparatus having a control unit in accordance with the first aspect, wherein the apparatus has at least one function under the control of the control unit.

For example, the apparatus may take the form of a vehicle.

According to another aspect of the invention, there is provided a method of assembling a control unit for an apparatus, the method comprising pre-forming a circuit-carrying member in a first pre-forming step; providing a printed electronic circuit on the circuitcarrying member to provide a function of the apparatus, in use; placing a pliable laminate layer onto the printed electronic circuit; and optionally cooling or setting the pliable laminate layer, thereby to form a laminate encapsulation layer over at least a part of the printed electronic circuit.

In one embodiment, the method may comprise pre-forming a second member in a second pre-forming step and, following the first and second pre-forming steps, placing the pliable laminate layer between the circuit-carrying member and the second member so as to form the laminate encapsulation layer on the printed electronic circuit, for example once cooled or set.

The setting of the pliable laminate layer may be achieved by UV curing, for example.

A simple and convenient manufacturing method can therefore be achieved to provide a lightweight, robust and low cost control unit for numerous applications.

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 an exploded view of a control unit of a first embodiment of the invention which may be used in a vehicle of the type shown in Figure 1;

Figure 3 is a plan view of a printed electronics layer forming part of the control unit in Figure 2;

Figure 4 is a schematic cross section of the control unit in Figure 2 formed using a single shot injection moulding process;

Figure 5 is a schematic cross section of a control unit of a second embodiment, also formed using a single shot injection moulding process;

Figure 6 is a schematic cross section of a control unit of a third embodiment, formed using a twin shot injection moulding process;

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

Figure 8 is a perspective view of a control unit of a fifth embodiment with only partial encapsulation of the printed electronics layer;

Figure 9 is a schematic cross section of a control unit of a sixth embodiment, comprising a heat sink arrangement;

Figure 10 is a schematic view cross section of a control unit of a seventh embodiment with a different heat sink arrangement to that shown in Figure 9;

Figure 11 is a schematic perspective view of a control unit having a three layer structure formed by a lamination process;

Figure 12 is a schematic cross section of a printed electronics layer which may be used in embodiments of the invention;

Figure 13 is a perspective view of a portion of the printed electronics layer in Figure 12 to show a support structure thereof; and

Figure 14 is a perspective view of a portion of a printed electronics layer in an alternative embodiment to that shown in Figure 13 to show an alternative support structure for the printed electronics layer.

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 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 presentation surface 16 to the user 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 a laminate encapsulation 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 noninteracting surface that is usually hidden from the view of the user. The A- and Bsurfaces 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 circuit-carrying member of the control unit 10 (i.e. that component upon which the electronic circuit 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 lamination process to form the layer 22.

Referring to Figure 2, 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 (not visible in Figure 2) 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, 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. 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 flexiglass.

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 encapsulation process with the intermediate layer 22.

The materials selected for the first and second pre-formed elements 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.

Figure 3 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 2. When in situ within the vehicle the Bsurface 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 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 2. 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, orflexi glass.

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 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.

Once the encapsulation 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 Asurface 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 encapsulation layer 22 between the first and second members to provide rigidity and structure to the unit, and to protect the electronic components.

Figures 4 and 5 are schematic views of two possible configurations for the control unit 10. In Figure 4 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 encapsulation 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. It will be appreciated that Figures 4 and 5 are schematic only, and so the relative thicknesses of the layers 14, 18, 22 as shown is not necessarily representative of layer thickness in a production embodiment.

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 encapsulation 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 5 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. As described in further detail below, the encapsulation material is introduced into the mould to produce the encapsulation layer on the reverse side of the first member 14, encapsulating the electronic components 30, 32, 34 and conductive tracks 38.

The embodiment of Figure 6 is similar to Figure 4 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 encapsulation 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. The encapsulation material is laid in the mould, on top of the second member. Using a second mould the hard coat 50 is then formed at the front face of the structure using an injection moulded material (i.e. the hard coat is formed directly onto the encapsulation layer 22) or another laminate layer.

Figure 7 is an alternative control unit in which enhanced depth effects may be produced 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 5. The rear surface of the first member 14 is encapsulated by the encapsulation layer 22, together with the electronic components 30, 32, 34 and the graphical features 24. A relatively thick and transparent front layer 52 is then formed on the front face. 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 8 shows another control unit in which the encapsulation of the printed electronic components by the encapsulation 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.

To counter any damage which may arise during the assembly process, 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. This ensures that adequate current can still be applied to components of the printed electronic circuit, even if some of the tracks break during assembly.

In order to provide additional protection for the more thermally sensitive electronic components it may be beneficial to incorporate a heat-sink 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-sink 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 sink feature, in the form of a thermally conductive element, and embodiments of the invention in which a heat sink feature is included will now be described.

Figure 9 shows an embodiment of the control unit 10 which is similar to Figure 6 in that it includes a first member 14 which defines an A-surface 16 of the control unit, either a presentation surface to the user or a surface with which the user interacts, 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-sink 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. 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 9. The heat sink 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 sink is therefore advantageous in manufacture of the control unit, and during its use.

The material of the thermally conductive layer may be graphene 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.

Figure 10 shows an alternative embodiment of the control unit 10 provided with a heatsink 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 9, 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-sink feature which does not form a part of the final control unit structure, as in Figures 9 and 10, 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 sink 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 sink arrangement may be configured to conduct heat to the printed electronic circuit, for example, without limitation if there are other features of the control unit require heat to be transferred away from them.

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 over head control panel described previously and as shown in Figure 2. 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 deadsurface of the glove compartment lid.

In another embodiment (not shown), the control unit forms a part of a vehicle sunvisor. 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 method by which the control unit 10 of any of the aforementioned embodiments may be formed will now be described. As described previously, the first member 14 defines an A-surface 16 which carries graphical features as indicators to the user about how to control the unit. The second member 18 defines a B-surface 20 which carries the various electronic components and conductive tracks (not shown in Figure 11). The third member 22, which is situated between the first and second members 14, 18, takes the form of a lamination layer such as a glue layer.

In order to assemble the control unit 10 using the lamination process the first member 14 is first pre-formed using a thermoforming process, as described previously, and is laid into a mould. The second member 18 is formed using a similar process, as described previously, and is laid into a facing mould. The glue layer 22 is then laid onto the first or second member 14, 18. 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 22 is laid onto the first or second members 14, 18 the mouldings are brought together to apply pressure to the parts, sandwiching the glue layer 22 between the first and second members 14, 18. Heat is then applied to the structure so that the glue moulds itself exactly to the shape of the first and second members 14, 18 and adheres the parts together. The presence of the glue on the second member 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 14, 18 securely together in a rigid structure with the glue forming an intermediate layer 22 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 14, 18 may be removed if the graphical features are laid directly into a mould rather than applying them to a first member 14. The glue is then laid directly into the mould, on top of the graphical features, and is sandwiched together with the second member 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 high temperatures and pressures are not required during the assembly process, and encapsulation of the printed electronic circuit is achieved using just a pliable glue layer which is mouldable in response to relatively low heat. Suitable materials for the lamination process include resins, vinyls, and ethylene copolymer resins. The pliable laminate material may be set by cooling or curing (e.g. UV curing).

Figure 11 is a schematic, perspective view of a laminated control unit structure 10 which may be achieved using the lamination process described previously for the laminate encapsulation layer 22, and applied in a structure having a laminate circuitcarrying member 14 and a laminate second member 18 also.

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, formed using an injection moulding process, 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 12 shows one possible configuration of the second member 18 which may be used to form a part of the control unit 10 in an embodiment where the control unit 10 takes the form of a display unit. The configuration shown in Figure 12 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 for the unit 10.

The printed electronics are deposited onto the backlight layer 73 which provides a supporting structure to the second member 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 sink 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 inkjet 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 13 shows the array of support elements 76 formed using a 3D printing process, as described previously, whereas in Figure 14 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 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 18.

The embodiments in Figures 12 to 14 have 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.

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.

Claims

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

a circuit-carrying member provided with a printed electronic circuit configured to provide a function of the apparatus; and a laminate encapsulation layer encapsulating at least a part of the printed electronic circuit.

2. The control unit as claimed in claim 1, comprising a presentation surface visible to a user of the apparatus, in use.

3. The control unit as claimed in claim 2, wherein the circuit-carrying member defines the presentation surface.

4. The control unit as claimed in claim 2, comprising a second member which defines the presentation surface.

5. The control unit as claimed in claim 4, wherein the second member comprises a pre-formed layer.

6. The control unit as claimed in claim 4 or claim 5, wherein the second member is spaced from the circuit-carrying member by the laminate encapsulation layer to define at least a three-layer structure for the control unit.

7. The control unit as claimed in any of claims 2 to 6, comprising a componentcarrying surface which carries the printed electronic circuit and wherein the component-carrying surface is on the reverse side of the circuit-carrying member to the presentation surface.

8. The control unit as claimed in any of claims 2 to 7, wherein the presentation surface defines a user-interaction surface for receiving a user command, and wherein the printed electronic circuit is operable in response to the user command.

9. The control unit as claimed in claim 8, 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.

10. The control unit as claimed in claim 8 or claim 9, wherein the printed electronic circuit comprises a plurality of conductive tracks for carrying current to at least one electronic component of the printed electronic circuit.

11. The control unit as claimed in claim 10, 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 command.

12. The control unit as claimed in claim 10 or claim 11, wherein a greater number of conductive tracks is provided on the printed electronic circuit than is required to provide adequate current to at least one electronic component of the printed electronic circuit, thereby to provide track redundancy in the event of breakage and/or failure of one or more of the conductive tracks.

13. The control unit as claimed in any of claims 2 to 12, comprising an additional layer provided on the presentation surface to provide an aesthetic finish to the control unit.

14. The control unit as claimed in claim 13, wherein the additional layer is a veneer which complements a surface of the apparatus in which the control unit is used.

15. The control unit as claimed in claim 13 or claim 14, wherein the additional layer is a protective coating.

16. The control unit as claimed in any of claims 13 to 15, wherein the additional layer is an injection moulded layer.

17. The control unit as claimed in any of claims 13 to 16, wherein the additional layer is provided with one or more cut outs.

18. The control unit as claimed in any of claims 2 to 17, wherein the presentation surface is provided with at least one graphical feature to provide an indication to the user about at least one function of the printed electronic circuit.

19. The control unit as claimed in any of claims 1 to 18, comprising a thermally conductive element encapsulated at least partially within the laminate encapsulation layer and configured to conduct heat to or away from the printed electronic circuit.

20. The control unit as claimed in claim 19, wherein the thermally conductive element is in thermal contact with the printed electronic circuit.

21. The control unit as claimed in claim 20, 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 printed electronic circuit via the remote component.

22. The control unit as claimed in claim 21, wherein the thermally conductive element includes a thermal contact region configured to make thermal contact with the circuit-carrying member to conduct heat to or away from the printed electronic circuit via the circuit-carrying member.

23. The control unit as claimed in claim 21 or claim 22, wherein the thermally conductive element includes an extension piece which projects from the circuitcarrying member to define the thermal contact region.

24. The control unit as claimed in any of claims 19 to 23, wherein the thermally conductive element is a layer of thermally conductive material laid onto at least a part of the printed electronic circuit.

25. The control unit as claimed in any of claims 1 to 24, wherein the circuit-carrying member comprises a pre-formed layer.

26. The control unit as claimed in any of claims 1 to 25, wherein the circuit-carrying member is provided with a plurality of structural supports to enhance rigidity of the control unit.

27. The control unit as claimed in claim 26, wherein the printed electronic circuit comprises a plurality of electronic components, and wherein the structural supports are interspersed between the electronic components.

28. The control unit as claimed in any of claims 1 to 27, configured for use in a vehicle.

29. The control unit as claimed in claim 28, wherein the printed electronic circuit 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.

30. The control unit as claimed in any of claims 1 to 29, wherein the circuit-carrying member is a pre-formed member.

31. The control unit as claimed in any of claims 1 to 30, wherein the laminate encapsulation layer is formed from a material which is pliable when heated, and less pliable or rigid when cooled or set.

32. Apparatus comprising the control unit as claimed in any of claims 1 to 31.

33. The apparatus as claimed in claim 32, in the form of a vehicle.

34. A method of assembling a control unit for an apparatus, the method comprising pre-forming a circuit-carrying member in a first pre-forming step; providing a printed electronic circuit on the circuit-carrying member to provide a function of the apparatus, in use; placing a pliable laminate layer onto the printed electronic circuit to form a laminate encapsulation layer over at least a part of the printed electronic circuit.

35. The method as claimed in claim 34, comprising pre-forming a second member in a second pre-forming step; and following the first and second pre-forming steps, placing the pliable laminate material between the circuit-carrying member and the second member so as to form the laminate encapsulation layer on the printed electronic circuit.

5

36. A control unit substantially as herein described with reference to the accompanying Figures 2 to 14.

37. A vehicle substantially as herein described with reference to the accompanying Figures 2 to 14.

38. A method substantially as herein described with reference to the accompanying Figures 2 to 14.

Intellectual

Property

Office

Application No: GB1617061.5 Examiner: Nadeem Khan