Transparent structure with electrically conductive elements

Abstract

An electrical current transmission system for transmitting an electrical current to an object via a substantially transparent structure is disclosed. The substantially transparent structure includes at least one transparent layer in the form of a flexible film sheet and at least two transparent electrically conductive elements. Each of the electrically conductive elements are separated by a part of the structure which is electrically insulating. Each electrically conductive element comprises a first busbar for connection to an external power supply, and a second busbar for transfer of electrical current to the object. Each of the first and second busbars comprises a layer of a low resistance conductor applied to each conductive element. The structure is a laminar structure and the busbars and the electrically conductive elements are each oriented parallel to the at least one transparent layer.

Description

[0001] Transparent Structure with Electrically Conductive Elements The present invention relates to a flexible transparent structure having electrically conductive elements contained therein.

[0002] Background of the Invention

[0003] GB2565041, to the present applicant, describes an electrical current transmission system for transmitting an electrical current to an object via a substantially transparent structure, the structure including transparent electrically conductive elements in the form of electrically conductive layers. The system described in this document was designed to be used with glass panels provided with electrically conductive coatings, such as indium tin oxide (ITO) coatings. Thin film applications are desirable since the flexibility of film is potentially very useful, thin films are less restrictive in shape and form and have reduced weight.

[0004] It would be desirable to provide an improved transparent electrical current transmission system.

[0005] Summary of the Invention

[0006] According to a first aspect of the invention there is provided an electrical current transmission system for transmitting an electrical current to an object via a substantially transparent structure, wherein the substantially transparent structure includes at least one transparent layer in the form of a flexible film sheet and at least two transparent electrically conductive elements; wherein each of the electrically conductive elements are separated by a part of the structure which is electrically insulating; and wherein each electrically conductive element comprises a first busbar for connection to an external power supply, and a second busbar for transfer of electrical current to the object, and each of the first and second busbars comprises a layer of a low resistance conductor applied to each conductive element; wherein the structure is a laminar structure and the busbars and the electrically conductive elements are each oriented parallel to the at least one transparent layer.The incorporation of busbars into the substantially transparent structure allows higher power devices to be driven by the sheet and enhances the ability of the sheet to handle more current.

[0007] The electrical current transmission system may be arranged to transmit an electrical current to more than one object, and the electrically conductive elements may be provided with additional busbars for transfer of electrical current to additional objects.

[0008] The electrically conductive elements may comprise transparent electrically conductive coatings applied to the at least one transparent layer. The transparent electrically conductive coatings may be selected from the group comprising: conductive indium Tin Oxide, silver nanowire film and transparent conductive inks.

[0009] At least one of the transparent electrically conductive elements may comprise a conductive film which includes an optical grade metallic mesh. The optical grade metallic mesh may be desposited on the surface of the film or may be laminated thereon. The metallic mesh may be fabricated from a metal selected from the group comprising: stainless steel, copper, silver, aluminium, and nickel.

[0010] The flexible film sheet may be a Polyethylene Terephthalate (PET) film.

[0011] At least one busbar may comprise a layer of conductive tape.

[0012] At least one busbar may comprise a layer of conductive ink. The conductive ink may comprise a blend of silver, carbon, and a non-conductive pigment. The conductive ink may comprise conductive particles and a non-conductive binder. The conductive particles may be selected from the group comprising: silver, carbon and copper.

[0013] Each of the first and second busbars may be printed onto the electrically conductive elements using a technique selected from group comprising inkjet printing, silk screen printing or using a CNC plotter.The part of the structure which is electrically insulating may comprise at least one portion of the at least one transparent layer which is not provided with an electrically conductive coating.

[0014] The part of the structure which is electrically insulating may comprise at least one portion of the at least one transparent layer in which the electrically conductive coating has been removed by etching, preferably laser etching.

[0015] Where the electrically conductive elements comprise metallic mesh, the part of the structure which is electrically insulating may comprise at least one portion of the at least one transparent layer in which the metallic mesh has either been removed by etching, or the mesh broken such that the conductive elements are no longer electrically connected. Preferably etching is performed using a laser.

[0016] Each transparent electrically conductive element may comprise a separate layer and the part of the structure which is electrically insulating may comprise a non-conductive interlayer oriented parallel to the electrically conductive elements and located between the electrically conductive elements.

[0017] The electrical current transmission system may be in the form of a substantially transparent cable in which at least one transparent layer is elongate, having a length which is greater than the width. The first and second busbars are preferably located adjacent to opposing ends of the elongate transparent layer

[0018] Brief Description of the Drawings

[0019] In the drawings, which illustrate the prior art, and a preferred embodiment of the apparatus of the invention, and are by way of example:Figure la illustrates an exploded perspective view of a transparent powered panel including a pair of transparent electrically conductive elements, the panel shown powering a single lamp;

[0020] Figure lb illustrates a cross section through the lamp of Figure la;

[0021] Figure 2a illustrates a cross section through a laminated transparent panel, the panel including one non-conductive transparent sheet, and one electrically conductive transparent sheet including a pair of transparent electrically conductive elements;

[0022] Figure 2b illustrates the panel of Figure 2a, with apertures added to access busbars through the electrically conductive transparent sheet;

[0023] Figure 2c illustrates electrical connectors connected to the transparent electrically conductive elements of the panel of Figure 2b;

[0024] Figure 3a illustrates an alternative location of access apertures in the panel of Figure 2a, accessing the transparent electrically conductive elements through the non-conductive transparent sheet;

[0025] Figure 3b illustrates electrical connectors connected to the transparent electrically conductive elements of the panel of Figure 3a;

[0026] Figure 4a illustrates a plan view of a transparent powered panel;

[0027] Figure 4b illustrates the panel of Figure 4a with a series of LEDs attached thereto;

[0028] Figure 5a is an exploded perspective view of a transparent powered panel powering a single lamp with electrical connectors connected through the non-conductive transparent sheet;

[0029] Figure 5b is a cross section through the lamp of Figure 5a;Figure 6 is an exploded perspective view of a transparent powered panel powering a pair of lamps, with the electrical connectors connected through the conductive transparent sheet;

[0030] Figure 7 is an exploded perspective view of a transparent powered panel powering a pair of lamps with electrical connectors connected through the non-conductive transparent sheet;

[0031] Figure 8a illustrates an exploded perspective view of a transparent powered panel including three transparent electrically conductive elements, the panel powering a single lamp and including a data transfer circuit, where the electrical connectors are connected through the conductive transparent sheet;

[0032] Figure 8b is a cross section through the lamp of Figure 8a;

[0033] Figure 9a illustrates an exploded perspective view of a transparent powered panel including three transparent electrically conductive elements, the panel powering a single lamp and including a data transfer circuit, where the electrical connectors are connected through the non-conductive transparent sheet;

[0034] Figure 9b is a cross section through the lamp of Figure 9a;

[0035] Figure 10 illustrates an exploded perspective view of a transparent powered panel including three transparent electrically conductive elements, the panel powering a pair of lamps and including a pair of data transfer circuits, where the electrical connectors are connected through the conductive transparent sheet;

[0036] Figure 11 illustrates an exploded perspective view of a transparent powered panel including three transparent electrically conductive elements, the panel powering a pair of lamps and including a pair of data transfer circuits, where the electrical connectors are connected through the non-conductive transparent sheet;Figure 12a illustrates an exploded perspective view of a transparent powered panel including a pair of transparent electrically conductive elements located in separate layers, the panel powering a single lamp;

[0037] Figure 12b illustrates a cross section through the lamp connectors of Figure 12a;

[0038] Figure 13 illustrates a perspective view of a transparent powered panel in the form of a transparent power cable, the cable including a pair of transparent electrically conductive elements;

[0039] Figure 14 illustrates the transparent power cable of Figure 13 used to power a screen;

[0040] Figure 15a illustrates an exploded perspective view of a transparent powered panel in the form of a transparent power cable, the panel including three transparent electrically conductive elements; and

[0041] Figure 15b illustrates a cross section through the transparent power cable of Figure 15a, taken along one of the electrically conductive elements.

[0042] Detailed Description of the Preferred Embodiments

[0043] Figure la and lb illustrate a simplified example of a transparent powered panel according to the invention. Figure la is an exploded perspective view, illustrating a first transparent sheet 10 which is provided with a conductive coating on one face (illustrated as a dotted surface in figure la). The transparent sheet may be a glass panel, or may be a flexible film panel, such as a PET film sheet. The conductive coating may be a conductive indium tin oxide layer but other conductive coatings are available. Indium tin oxide (ITO) is one of the most widely used transparent conducting oxides, and ITO-coated PET film is available commercially. Alternative conductive coatings include PEDOT™ conductive inks and metal nanowires.Optical grade metallic meshes offer an alternative to conductive coatings, as such meshes can also function as transparent conductors.

[0044] In the example in Figure la, the transparent conductive coating has been etched away along a line 14, for example using a laser, effectively splitting the conductive coating into two parts, with an electrically insulating gap between the two parts. This means that the sheet includes two separate electrically conductive elements 12a and 12b located in the same plane. Alternatively, the first transparent sheet 10 could be coated with the conductive coating such that there is a gap along the line 14, meaning there is no requirement to etch away part of the conductive coating.

[0045] Areas of the conductive surfaces are provided with pairs of busbars 16a, 16b and 18a, 18b. Busbars are preferably printed onto the conductive side of the film using a conductive ink, for example silver ink. Alternatively, the busbars may comprise a conductive tape, such as a copper tape. The busbars have higher thermal conductivity compared to ITO. This may aid heat dissipation and allow systems to handle higher currents without overheating. Busbars are added to the film layer to reduce the resistance at the points at which power flows into and out of the film.

[0046] Referring back to Figures la and lb, the transparent film sheet 10 is laminated with a layer of adhesive 20 to a sheet of transparent non-conductive film or glass sheet 22, enclosing the conductive surfaces 12a, 12b and busbars 16a, 16b, 18a, 18b between the two film sheets, as illustrated in the cross-sectional view of Figure 2a.

[0047] To access the busbars, holes 24a, 24b, 26a, 26b are made in one of the sheets. In Figure 2b holes have been made in the first transparent sheet 10. This allows connectors 28a, 28b, 30a and 30b to be attached to the respective busbars, via the holes, as illustrated in Figure 2c. Attachment of the electrical connectors to the busbars may be via any suitable method that provides a conductive connection, for example this could be done by soldering, using aconductive adhesive, friction bonding or by micro riveting. Holes can be made by piercing the film sheet, or using heat to melt away a small portion of the film 10.

[0048] Alternatively, holes to access the busbars may be made in the non-conductive film layer 22, as shown in Figure 3a. It is not important which side of the film is cut to access the busbars.

[0049] Power is supplied to the electrically conductive elements 12a, 12b via connectors 30a, 30b connected to one pair of busbars 16a, 16b, typically located close to an edge of the sheet 10. The connectors may be connected to mains power, or to a battery.

[0050] The other pair of busbars 24a, 24b are for connection to a device which requires electrical power, for example a lamp 32, a matrix of LEDs, a digital camera, or a display.

[0051] The sheet of non-conductive film 22 to which the first film sheet 10 is attached could also be a glass sheet, for example a shop window, with the conductive face of the film 10 adhered directly to the glass.

[0052] The busbars are non-transparent. The busbars for connection to a power supply are located at the edge of the panel, and the busbars for connection to a device such as a lamp are sized such that they preferably can’t be seen once the lamp is connected, as shown in Figures 4a and 4b. The etched line is also not visible from a distance, and the assembly gives the impression that the lamp or LEDs are suspended on a transparent sheet. Figure 4a illustrates a pair of busbar perimeter frames 16a, 16b formed around the edge of the film sheet 10 with a gap adjacent to the etched line 14. A power supply 13 is attached to the perimeter busbars. A pair of substantially central busbars 18a, 18b is then provided for powered devices to connect to, reducing resistance when power is extracted from the sheet. Figure 4b illustrates a ring of LEDs 34 connected to the central busbars, allowing a series of LED to be lit in the centre of a transparent sheet. The ring of LEDs 34 covers the busbars 18a, 18b so they are not visible when viewed from the LED side of the sheet.Figures 5a and 5b illustrate a further example of a transparent powered panel. This example is very similar to that described in relation to Figures la and lb, and like features have been labelled with like reference numerals. In this example, access to the busbars is through the non-conductive sheet 22, through the opposite of the structure compared to the previous example.

[0053] More than one device can be powered by the transparent panel. For example, figure 6 shows two lamps 32, 32’ being powered by the sheet, with two pairs of device busbars 18a, 18b and 18a’, 18b’ and associated connectors 28a, 28b and 28a’, 28b’, the connectors shown connecting through holes in the first conductive sheet 10. The example illustrated in Figure 7 is very similar, with the access to the busbars through the opposite side of the panel.

[0054] Figures 8a, 8b, 9a and 9b illustrate exploded views of a transparent panel provided with three separate electrically conductive elements 12a, 12b and 12c. In this example the conductive coating on the sheet 10 has been etched away along two lines 14, 14’ effectively splitting the transparent conductive coating into three parts. This third channel can be used as a data line. Areas of the conductive surfaces are provided with groups of busbars 16a, 16b, 16c, and 18a, 18b and 18c in the same manner as previously described. As with the previous example, the film is then sandwiched together with a layer of adhesive 20 to a sheet of non-conductive film 22, enclosing the transparent conductive elements and busbars between the two film sheets.

[0055] To access the busbars, holes 24a, 24b, 24c and 26a, 26b, 26c are made either in the first sheet 10 (as in Figures 8a and 8b), or the non-conductive film 22 (as in Figures 9a and 9b), in the same was as described in relation to the previous examples. This allows connectors 28a, 28b, 28c and 30a, 30b and 30c to be attached to the respective busbars, via the holes.

[0056] Power is supplied to the electrically conductive elements 12a, 12b, 12c via connectors 30a, 30b, 30c connected to the first set of busbars 16a, 16b, 16c typically located close to an edge of the sheet 10. The connectors may be connected to mains power, or to a battery.The other set of busbars 18a, 18b, 18c are for connection to a device which requires electrical power, such as a lamp 32 or a series of LEDs. One of the electrically conductive elements, for example 12c in the example illustrated in Figures 8a and 9a, can be used as part of a data transfer circuit, D. There is no requirement for the electrically conductive elements to be of equal size.

[0057] Figures 10 and 11 illustrate further examples of the panels of Figures 8a and 9a, where each panel is configured to power a pair of lamps 32, 32’ and pair data circuits.

[0058] Figures 12a and 12b illustrate an alternative embodiment of the invention, in which the electrically conductive elements are in layers. A first film layer 10 is provided with a transparent electrically conductive coating 12 on one face (illustrated as a dotted surface in figure 12a), and a second film layer 10’ is provided with a transparent electrically conductive coating 12’ on one face (again, illustrated as a dotted surface). Busbars 16a, 16b and 18a, 18b are located on the electrically conductive layers, with one of each pair of busbars located on a different electrically conductive coating. The two film layers are laminated together with an electrically insulating interlayer 15 between the two conductive elements. To access the busbars, holes can be made through either side of the panel, in a similar way to that previously described, or, where busbars are located at the edge of the panel, electrical connectors such as wires 17a, 17b or conductive strips can be inserted between the layers during the lamination process.

[0059] Figure 13 illustrates an alternative aspect of the invention, in which the transparent powered panel is a transparent cable, or a transparent strip used to transfer power. An example of a transparent cable 10’ comprises a first transparent sheet 110 and a pair of electrically conductive elements 112a, 112b (illustrated as a dotted surface in figure 13). For transparent cable applications the transparent electrical conductor is preferably an optical grade metallic mesh, or a multi layered splutter coating of metals including silver, ITO, graphene or carbon nanotubes. Optical grade metallic mesh is highly transparent, typically providing at least 75% light transmittance. The wires forming the metallic mesh are typically less than 100pm indiameter. The mesh is either embedded within the film layer or attached thereto. Stainless steel conductive mesh is lightweight and has excellent conductivity and low resistance. Transparent conductive metal mesh PET film is a commercially available PET film which includes an embedded copper grid. The conductive layer is a very fine etched mesh and the film is highly transparent, with low resistance. In conductive metal mesh film, a finer mesh wire diameter results in lower sheet resistance, enhancing electrical conductivity. One example of a commercially available PET film includes a mesh fabricated from copper wires with a diameter of 17pm, and a mesh spacing of 143 pm. The visible light transmittance is greater than or equal to 75%.

[0060] As with the previous examples, the metallic mesh is etched away along a line 114 to split the mesh into two electrically conductive elements 112a, 112b located in the same plane. The metallic mesh can be etched away using laser. Alternatively, two strips of conductive film may be mounted side by side, ensuring an electrically insulating gap is present between the two metallic mesh conductors.

[0061] Areas of the conductive surfaces are provided with pairs of busbars 116a, 116b, 118a, 118b, as with the previous examples. To form a transparent cable the busbars are located at opposing ends of the film sheet. The film sheet may be elongate with busbars located at both ends. The lengths of the cable could be up to 2m, or could be longer. The width of the cable is also variable, depending on the application, and the required power, since the resistance of the cable reduces as the width is increased. The cable may be fairly narrow, for example 20mm, but could also be wider if more power is required. As with the previous examples, busbars are preferably printed onto the conductive side of the film using a conductive ink, for example silver ink. Alternatively, the busbars may comprise a conductive tape, such as a copper tape.

[0062] The transparent film sheet 110 is then laminated together with a layer of adhesive 120 to a sheet of transparent non-conductive film 122, enclosing the conductive surfaces 112a, 112band busbars 116a, 116b, 118a, 118b, in between the two film sheets. The busbars may be accessed by forming holes in either side of the film layers as described with reference to the panel examples, however an alternative means for accessing the busbars is illustrated in Figure 13, where the non-conductive film 122 is provided with a series of openings 124a, 124b, 126a, 126b prior to lamination, meaning that connectors 128a, 128b, 130a, 130b can connect directly to the busbars through the openings.

[0063] The transparent cable allows an object, such as a screen 36 illustrated in Figure 14 to be powered using a cable 10’ which is substantially transparent, meaning that the powered object can be mounted on a glass surface, such as a window 38, and can appear suspended on the glass.

[0064] As illustrated in Figures 15a and 15b, the transparent cable may also comprise three electrically conductive elements 112a, 112b and 112c, by providing three separate sections of metallic mesh. This may be achieved by etching away the metallic mesh along two lines 114, 114’. Alternatively, three strips of conductive film may be mounted side by side, ensuring an electrically insulating gap is present between each of the metallic mesh conductors. As described previously in relation to the transparent powered panel embodiments, providing three separate conductive elements allows for transfer of data as well as power through the cable.

[0065] An electrical current transmission system using flexible conductive sheets is lighter weight than glass-based systems, and also allows for retrofitting onto existing glass structures. Incorporation of busbars into a transparent conductive sheet allows higher power devices to be driven by the sheet. For example, brighter signage, LED clusters, power sockets, strip lights or electromagnets. Prior art systems use micro LEDs which require very small current per micro LED, meaning that high resistance of the sheet itself is not an issue. The addition of busbars to the sheet significantly enhances the ability of the sheet to handle more current. The busbars act as a low-resistance pathway for current, enabling more efficient distribution across the sheet and reducing the risk of localised overheating or damage.

Claims

Claims1. An electrical current transmission system for transmitting an electrical current to an object via a substantially transparent structure, wherein the substantially transparent structure includes at least one transparent layer in the form of a flexible film sheet, and at least two transparent electrically conductive elements; wherein each of the electrically conductive elements are separated by a part of the structure which is electrically insulating; and wherein each electrically conductive element comprises a first busbar for connection to an external power supply, and a second busbar for transfer of electrical current to the object, and each of the first and second busbars comprises a layer of a low resistance conductor applied to each conductive element; wherein the structure is a laminar structure and the busbars and the electrically conductive elements are each oriented parallel to the at least one transparent layer.

2. An electrical current transmission system according to Claim 1, wherein the at least two electrically conductive elements comprise transparent electrically conductive coatings applied to the at least one transparent layer.

3. An electrical current transmission system according to Claim 2, wherein the transparent electrically conductive coating is selected from the group comprising: conductive indium Tin Oxide, silver nanowire film and transparent conductive inks.

4. An electrical current transmission system according to Claim 1, wherein the or each transparent electrically conductive element comprises an optical grade metallic mesh.

5. An electrical current transmission system according to Claim 4, wherein the mesh is a nanoscale metallic mesh.

6. An electrical current transmission system according to Claim 4 or 5, wherein the metallic mesh is fabricated from a metal selected from the group comprising: stainless steel, copper, silver, aluminium, and nickel.

7. An electrical current transmission system according to any preceding claim, wherein at least one busbar comprises a layer of conductive tape.

8. An electrical current transmission system according to any of claims 1 to 6, wherein at least one busbar comprises a layer of a conductive ink.

9. An electrical current transmission system according to Claim 8, the conductive ink comprising conductive particles, and a non-conductive binder, the conductive particles selected from the group comprising: silver, carbon and copper.

10. An electrical current transmission system according to claim 8 or 9, wherein each of the first and second busbars are printed onto the electrically conductive elements using a technique selected from group comprising inkjet printing, silk screen printing or using a CNC plotter.

11. An electrical current transmission system according to any preceding claim, wherein the part of the structure which is electrically insulating comprises at least one portion of the at least one transparent layer which is not provided with electrically conductive elements.

12. An electrical current transmission system according to any preceding claim, wherein the part of the structure which is electrically insulating comprises at least one portion of the at least one transparent layer in which the electrically conductive coating has been removed.

13. An electrical current transmission system according to claim 12, wherein the electrically conductive coating has been removed by etching.

14. An electrical current transmission system according to any of claims 1 to 10, wherein each transparent electrically conductive element comprises a separate layer and the part of the structure which is electrically insulating comprises a non-conductive interlayer oriented parallel to the electrically conductive elements and located between the electrically conductive elements.

5. An electrical current transmission system according to any of claims 4 to 14, wherein the at least one transparent layer is elongate, and wherein the first and second busbars are located adjacent to opposing ends of the elongate transparent layer.

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