GB2586810A

GB2586810A - Case for mobile device

Info

Publication number: GB2586810A
Application number: GB1912646.5A
Authority: GB
Inventors: Thomas Darvill Daniel; Marcus Griffith James; John Mullen William; Han Wen Ting Thomas; David Montgomery Freethy Jack; Atherton Nicolas; David Peet Alexander
Original assignee: Mous Products Ltd
Current assignee: Mous Products Ltd
Priority date: 2019-09-03
Filing date: 2019-09-03
Publication date: 2021-03-10
Also published as: WO2021044149A1; GB201912646D0

Abstract

There is provided a case for a mobile device; such as a mobile phone or tablet. The case 10 comprises: attachment means (30, figure 1) for attaching the case to the mobile device; a protective cover (50) comprising front and back surfaces 54,52, the protective cover being arranged such that the back surface 52 is adjacent a rear surface of the mobile device when the case is attached to the mobile device; and coupling means 70 located between the front and back surfaces of the protective cover for removably connecting accessories (not shown) to the case. The coupling means comprises a plurality of permanent magnets 74 arranged to form a Halbach array (72, figure 4) configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface 54 of the protective cover and to substantially cancel the magnetic field in the direction of the back surface 52 of the protective cover.

Description

CASE FOR MOBILE DEVICE

TECHNICAL FIELD

This invention relates to a case for a mobile device. Particularly, the disclosure relates to a case that can be attached to a housing of a mobile device, such as a mobile telephone or tablet, to protect the housing and/or screen of the device and to enable the attachment of accessories to the mobile device.

BACKGROUND

Mobile devices, such as mobile phones and tablet computers, are indispensable for many users. A large number of users, particularly digital natives, interact with their mobile devices for several hours each day and rely heavily on their devices to manage their daily lives. However, as devices become increasingly expensive and, at the same time, more fragile, inadvertent damage to an unprotected device may be highly disruptive to the user.

Accordingly, users now protect their devices against inadvertent damage using protective cases. As reliance on devices increases, users also wish that more can be done with their devices to allow greater interaction with the world around them. As a result, cases for mobile phones have been adapted to incorporate new uses, such as acting as a wallet as well as a case.

Another example of such adaptation is to provide a range of accessories that can be connected to the mobile device via the case. For example, the case may be mounted to a car mount to allow the case to be held at eye height while driving so that instructions can be adequately relayed without the user being required to touch the device. Alternatively, a detachable wallet may be attached to the case.

The connection may be achieved by the use of magnets. Some cases instead include a metallic plate that allows magnets in the external accessory to connect to the case.

Alternatively, magnets may be incorporated into the case, to connect with a metal plate or corresponding magnets in the accessory. However, in both cases, there is a possibility that these set-ups may interfere with the operation of equipment in the phone. For example, device navigation systems may be sensitive to magnetic fields.

In the art, to avoid any interference, the area of the case that is close to the navigation systems when the case is attached to the phone is left free of magnets. For example, in the Mous® Limitless 2.0 case, magnets are provided at the corners of triangle positioned to avoid an area near the compass technology. However, having only three magnets limits the magnetic coverage and the strength of the resultant magnetic field, which consequently has an impact on how the case can interact with and successfully connect with its accessories.

It is against this background that the present invention has been devised.

SUMMARY

According to an aspect of the present invention there is provided a case for a mobile device. The case comprises attachment means for attaching the case to the mobile device. The case comprises a protective cover. The protective cover comprises front and back surfaces. The protective cover is arranged such that the back surface is adjacent a rear surface of the mobile device when the case is attached to the mobile device. The case comprises coupling means located between the front and back surfaces of the protective cover for removably connecting accessories to the case. The coupling means comprises a plurality of permanent magnets. The plurality of permanent magnets are arranged to form a Halbach array. The Halbach array is configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface of the protective cover and to substantially cancel the magnetic field in the direction of the back surface of the protective cover.

The attaching means may be referred to as one or more attachments, connectors, or fasteners. The coupling means may be referred to as one or more couplers, coupling elements, connectors, pairers, pairing elements, or links.

The benefit of arranging permanent magnets to form a Halbach array is that the magnetic field is modified so that the strength of the field is greater in the direction that is away from the mobile device than towards the mobile device. The Halbach array therefore allows for the use of the case with the mobile device without the worry that there will be any interference with any equipment within the device that is sensitive to magnetic fields, such as navigational technology.

Moreover, a Halbach array can also be designed to have a high strength field in the vicinity of the front surface of the protective cover but to attenuate significantly after a short distance. This is in contrast to conventionally-arranged magnets, where the field strength does not attenuate as significantly. Accordingly, the case acts only to couple the accessories to it when the accessory is brought close to the case.

It will also be appreciated that augmentation of the magnetic field effectively improves the field strength so the connection between the case and the accessory will be improved. The improvement is achieved without the array occupying a greater volume or having a substantially greater weight within the case, so that the case's usefulness is maintained.

The coupling means may comprise a mount to which the Halbach array is secured. The mount may comprise a base provided between the Halbach array and the back surface of the protective cover. Providing a mount provides further opportunity to reduce the effect of the magnetic field in the direction of the back surface. Accordingly, the possibility of interfering with the sensitive equipment within the mobile device is further reduced. The mount also enables a connection point for the Halbach arrays to maintain them in position and to hold them within the protective cover.

The mount may comprise a recess in which the Halbach array is received. The Halbach array has a lower face in the direction of the back surface of the protective cover, an upper face in the direction of the front surface of the protective cover, and at least one side face between the lower and upper faces. The mount may cover the lower and side faces. The upper face may be left uncovered. By providing a recessed mount that covers at least one side, the mount acts to redirect the magnetic field in the direction of the upper face, thereby further augmenting the magnetic field directed through the front surface of the protective cover.

The mount may comprise a tab extending laterally from the base. The protective cover may comprise a stop that lies against the tab to prevent movement of the mount. The stop and tab may interact to prevent movement of the mount and, by extension, Halbach array, in the direction of the front surface of the protective cover. The tab and protective cover may interact to prevent lateral movement of the mount and Halbach array.

The mount may be fixed to the back surface of the protective cover. The mount may be formed of metal.

The plurality of permanent magnets may be arranged to form a plurality of Halbach arrays. The plurality of Halbach arrays may be arranged to be co-planar within the protective cover. Including more than one Halbach array in the case enables accessories to be coupled to the case in different locations, and in different orientations.

The plurality of Halbach arrays may be positioned outside or on a perimeter of an exclusion zone. The exclusion zone may represent an area of the protective cover that overlays one or more electronic components in the mobile device that are sensitive to magnetic flux and/or conductive materials when the case is attached to the mobile device. The plurality of Halbach arrays may be spaced around the perimeter of the exclusion zone. The exclusion zone may be circular. The plurality of Halbach arrays may be arranged into two pairs of Halbach arrays. One Halbach array of each pair of Halbach arrays may be diametrically opposite the other Halbach array of each pair of Halbach arrays. The Halbach arrays may be provided at opposite ends of a diameter of the circular exclusion zone. The two diameters may extend perpendicularly to one another. The two diameters may be at 45 degrees to one or more of the edges of the protective cover. The Halbach arrays of the two pairs of Halbach arrays may be spaced around the perimeter of the circular exclusion zone at 90 degree intervals. Alternatively, the Halbach arrays may comprise more than two pairs of Halbach arrays. The pairs of Halbach arrays may be spaced around the perimeter of the circular exclusion zone at a regular angle. For example, three pairs of Halbach arrays may be spaced around the perimeter at 60 degree intervals. The pairs of Halbach arrays may be spaced around the perimeter of the circular exclusion zone at any angle. Adjacent Halbach arrays may be spaced from one another around the perimeter of the exclusion zone at an angle. The angle may be 10, 20, 30, 40, 50, 60, 70, 80, or 90 degrees. The sensitive electronic component may be a wireless charging coil. Providing Halbach arrays around the perimeter of the wireless charging coil's circular exclusion zone is particularly useful in ensuring that the case is compatible with wireless charging pads, particularly those that have Qi certification.

The front surface of the protective cover may be defined by a plate. The Halbach array may abut the plate.

The protective cover may comprise a support structure. The coupling means may be received in an opening of the support structure.

The support structure may be disposed between the front and back surfaces. Alternatively, the support structure may define the front surface and/or the back surface.

The thickness of the support structure may be substantially equal to the thickness of the coupling means.

The protective cover may comprise a stiffening layer. The protective cover may comprise a cushioning layer. The stiffening layer may define the back surface of the protective cover. Alternatively, the cushioning layer may define the back surface of the protective cover. The coupling means may be attached to the stiffening layer. Alternatively, the coupling means may be attached to the cushioning layer. The cushioning layer may be formed of a microfibre material. A cushioning layer is useful in reducing damage that may be caused if grit or dust is trapped between the case and the mobile device.

According to another aspect of the invention, there is provided an accessory for attaching to the case as described above. The accessory comprises a supporting structure holding a coupling means for removably connecting the accessory to the front surface of the protective cover. The coupling means comprises a plurality of permanent magnets arranged to form a Halbach array. The Halbach array is configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface of the protective cover when the accessory is connected to the case.

According to another aspect of the invention, there is provided a kit of parts comprising the accessory and the case as described above.

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 DRAWINGS

In order that the embodiments of the invention may be readily understood, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 shows a perspective view of a case for a mobile device according to an embodiment of the invention; Figure 2 shows an exploded view of the case of Figure 1; Figure 3 shows a partial cross-section of the case of Figure 1; Figure 4 shows a schematic rear view of the case of Figure 1 indicating the location of magnetic arrays in the case; Figure 5 shows an example array of magnets as used in the case of Figure 1; Figure 6 shows a representation of how the array of magnets is arranged within the case of Figure 1; and Figure 7 shows a cross section of a case for a mobile device according to an alternative embodiment of the invention.

DETAILED DESCRIPTION

In general, described herein is a case for a mobile device configured to enable magnetic coupling of accessories to the case. The case is arranged to have a wide magnetic coverage within the case so that the coupling of accessories and the case is straightforward and can be achieved at a number of positions. The case also minimises magnetic interference with sensitive equipment within the mobile device.

Additionally, the case represents an improvement in the strength of the magnetic coupling compared to existing cases, while minimising the possibility of the case coupling to other magnetic or metallic objects. In other words, the magnetic field achieved in the case has several specific properties. Namely, it is weak, essentially negligible, on the side of the case that faces the mobile device in use, and relatively strong on the opposite side, the attenuation of the field is high over a short distance, and there are a sufficient number of equally spread magnet fields in the phone case to accommodate different placings and orientations of accessories. All this is achieved without large amounts of space being occupied by the magnets and without requiring heavy componentry within the case.

Such a case 10 for a mobile device is shown in Figure 1 and will be described below in relation to Figures 1 to 7. The case 10 in the embodiment of Figure 1 is for a mobile phone, particularly a smartphone, and is configured to attach to a mobile phone to cover a rear surface of the mobile phone in order to protect it. Although the case 10 is for a mobile phone in this embodiment, in other embodiments, a case may be for a tablet computer, a tablet, or a laptop computer in other embodiments.

The case 10 comprises an attachment means 30 and a protective cover 50. The attachment means 30, which is for attaching the case 10 to the mobile device, is in the form of a moulded rim 32. The rim 32 is moulded to conform to the outline of the mobile device, and attaches the case 10 to the mobile device by encircling the edges of the mobile device. The rim 32 has curved edges 34 to centre the mobile device in the rim 32 and to hold the device in place. To fit the mobile device into the case 10, the rim 32 is deformed slightly to insert the device into it. The rim 32 has buttons 36 and cut-outs 38 moulded into it. On the lower surface 40, three cut-outs 38 are provided, a central cut-out for allowing access to a charging port of the mobile device and two cutouts either side of the central cut-out to expose the loudspeakers and/or microphones and permit transmission of sound from and to the mobile device. Buttons and cut-outs are provided on the sides of the rim 32 to allow operation of corresponding buttons and switches on the mobile device. Although not shown here, the rim 32 may include damping material to absorb vibration and mitigate the effect of impacts against the case 10.

It will be appreciated that the attachment means 30 may be any attachment that attaches the case to the mobile device. For example, an elastic attachment may be used instead, that loops around part of the mobile device. Additionally, the locations of the cut-outs and buttons are provided as examples only. Buttons and cut-outs in a moulded rim may be placed at any suitable position to enable the correct functioning of the mobile device.

The protective cover 50 extends across the rim 32 to form the case 10. The protective cover 50 has a back surface 52 and an opposing front surface 54. Only the back surface 52 is visible in Figure 1. When the case 10 is attached to the mobile device, the back surface 52 of the protective cover 50 is adjacent a rear surface of the mobile device. The mobile device is pressed into the rim 32 so that its sides are encircled by the rim 32 and the rear surface of the mobile device is adjacent the protective cover 50. The protective cover 50 includes an aperture 56 for exposing the device camera.

The position of the aperture 56 is defined by where the device camera is positioned on the rear of the mobile device.

Although not provided in the present embodiment, the protective cover 50 may also extend to the front of the device to cover the forward surface of the device.

As can be seen in the exploded view of the case of Figure 2 and the partial cross-section of the protective cover 50 of Figure 3, the protective cover 50 includes a coupling means 70 for removably connecting accessories to the case 10, as will be discussed later, and is otherwise formed of a number of layers.

The front surface 54 of the case 10 is the uppermost surface shown in Figure 2 and 3. In other words, the lower surfaces shown in the Figures, those towards the bottom of the drawings, are those that are disposed closest to the mobile phone in use.

The front surface 54 of the protective cover 50 is defined, or at least partially defined, by a plate 58. The plate 58 is relatively thin and may be formed of a variety of materials. Example plate materials are aramid fibres, leather, marble, shell, or wood, although many other materials may be used to form the plate 58. The plate 58 may, in alternative embodiments, comprise more than one layer, such as a stiffener to complement a less rigid material.

The plate 58 fits into a recess 60 provided in a support structure 62. The plate 58 is appropriately secured within the support structure 62 using an adhesive. In other embodiments, the plate 58 may overlay the support structure 62 rather than fitting into a recess 60 thereof.

The support structure 62 provides an intermediate layer for the protective cover 50 between the back and front surfaces 52, 54. In the embodiment shown, the support structure 62 also comprises the rim 32. The support structure 62 is a rigid frame or housing, typically formed of a moulded plastic. Example materials are thermoplastic polymers, such as polycarbonates. As can be seen, the support structure 62 here defines the aperture 56 in the protective cover 50.

Formed in the support structure 62 are four openings 64 for receiving the coupling means 70. The coupling means 70 are provided in the form of four Halbach arrays 72, also referred to as multipole arrays, formed of a plurality of permanent magnets 74 and each secured to a respective mount 76. Each Halbach array 72 is received in its respective opening 64 in the support structure 62. The openings 64 extend through the support structure 62 so that, as can be seen in Figure 3, the support structure 62 surrounds the sides of each Halbach array 72 and mount 76. As can be seen in Figure 3, the support structure 62 is substantially the same depth as the Halbach array 72 and mount 76 combination, to ensure a fight fit within the opening 64. The dimensions of the opening 74 are such that the Halbach array 72 and mount 76 fit within the opening 64 while relative lateral movement is prevented.

To briefly address the remaining layers before considering the coupling means 70 and its arrangement within the layers in more detail, a stiffening layer 66 is provided on the other side of the support structure 62 to the plate 58. The stiffening layer 66 functions to stiffen the protective cover 50 and is the surface against which the coupling means 70 is secured and that holds the coupling means 70 within the openings 64 in the support structure 62. It is envisaged that the stiffening layer 66 may be formed of a woven fibre material, typically plastic such as a polycarbonate.

The back surface 52 of the protective cover 50 is defined by a cushioning layer 68. The cushioning layer 68, which here is formed of a soft material such as a microfibre material, overlays the stiffening layer 66 and lies adjacent the mobile device when the case 10 is attached to the mobile device. The cushioning layer 68 ensures that any debris that becomes trapped between the case 10 and the rear surface of the mobile device in use does not cause damage. This is achieved either by elastically deforming around the debris to limit its movement and prevent it from being pressed against the rear of the device, or by trapping and retaining the debris within a porous or open structure. Without a cushioning layer, debris particles trapped between two hard surfaces may create a point load on the rear of the device, causing damage. This is especially useful where the rear surface is formed of glass.

Therefore, as can be seen in Figure 3 the layers of the protective cover 50, from the front surface 54 to the back surface 52, are: the plate 58; the support structure 62 and coupling means 70; the stiffening layer 66; and the cushioning layer 68.

Returning now to the coupling means 70, reference will be made to Figures 2 to 6. Generally, the coupling means 70, as already discussed, is provided within the protective cover 50 between the front and back surfaces 54, 52 of the protective cover 50. The coupling means 70 is for the purpose of removably connecting accessories to the case 10. For example, a removable wallet may be attached to the case 10 via the coupling means 70 so that the wallet can be held connected to the case 10 and the device, but removed if the user wishes to use the wallet separately. In another example, the accessory may be a mounting accessory for use in a car to aid with navigation or for use in household or office tasks where the user does not wish to hold the device.

The coupling means 70 comprises the plurality of permanent magnets 74 arranged to form Halbach arrays 72. Four Halbach arrays 72 are provided in the embodiment shown in the Figures.

As will be well understood, a Halbach array 72 generally comprises an array of permanent magnets 74 arranged in a particular pattern of orientations as shown in Figure 4. A Halbach array 72, more specifically a planar Halbach array, typically comprises at least five magnets 77, 78, 79, 80, 81 arranged in a line and with their poles oriented in different directions. In some arrangements Halbach array may have a plurality of magnets in excess of five. The outer two magnets 77, 81 are arranged to have their north pole pointing upwards, and the centre magnet 79 is arranged to have its north pole point downwards. The remaining two magnets 78, 80 have their north poles pointing away from one another, outwardly. It will be appreciated that the terms upwards, downwards, and outwardly here refer to the orientation shown in Figure 4, and that these represent the relative directions in which the poles are facing. Provided the magnets 72 are arranged relative to one another in this formation, a Halbach array 72 is formed regardless of orientation of the whole array.

By arranging magnets 74 into a Halbach array 72 comprising this arrangement, a change in the usual magnetic field is observed. The interaction of the fields of the magnets creates an augmented, strong field on one side and an effectively cancelled, or at least substantially weaker, field on the other side. The augmented field is created on the upwards side, i.e. the side towards which the two outer magnets 77, 81 in the arrangement of Figure 5 point, and the weaker field is created on the opposite side.

The strong side is represented in Figure 5 by a plus sign, while the opposite side is represented by a minus sign.

As part of the coupling means 70, each Halbach array 72 is provided in and secured to its mount 76, as can be seen in Figure 3. The mount 76 has a recess 82 in which the Halbach array 72 is received. The mount 76 sits between the Halbach array 72 and the back surface 52 of the cover 50. In other words, the mount 76 acts as a cradle surrounding the rectangular Halbach array 72 on five of its six sides, leaving the upper, strong side (+) of the Halbach array 72 uncovered.

The upper surface (+) of the Halbach array 72, namely the surface where the strong, augmented magnetic field is found, is left uncovered so that the augmented magnetic field is not impacted by the presence of the mount 76. However, in covering the other surfaces of the Halbach array 72 and therefore by providing the mount 76 between the Halbach array 72 and the mobile device in use, the magnetic field directed through the back surface 52 of the protective cover 50 is minimised further.

Furthermore, the mount 76 is formed of a metal, typically steel or another ferrous alloy or metal. A metallic mount further reduces the strength of the magnetic field directed through the back surface 52 of the protective cover 50 and improves the attenuation of the field with distance. Accordingly, as the field has to travel through at least the mount 76, the stiffening layer 66, and the cushioning layer 68 before even reaching the outermost housing of the mobile device, the magnetic field is negligible when it reaches the mobile device.

The magnetic field through the front surface 54 of the protective cover 50 is also augmented by the arrangement of the layers 58, 62, 66, 68 and the mount 76. The mount 76 is configured to leave the upper surface (+) of the Halbach array 72 uncovered, while the support structure 62 and stiffening layer 66 are arranged to ensure that air gaps within the protective cover 50 are minimised and so that the Halbach array 72 is held against and abuts the plate 58 defining the front surface 54, thereby minimising attenuation of the magnetic field within the protective cover 50. Accordingly, the magnetic field through the plate 58 is optimised.

In general, therefore, a strong magnetic field is directed through the front surface 54 of the protective cover 50, while a weak magnetic field is directed through the back surface 52.

While the configuration of the Halbach array 72 and mount 76 individually improves the augmentation of the magnetic field, the arrangement of the Halbach arrays 72 within the protective cover 50 also provides particular advantages.

Referring particularly to Figures 2, 5, and 6, it can be seen that the coupling means 70 is arranged within the cover 50 to have a particular configuration relative to the device.

More specifically, the Halbach arrays 72 are arranged to be on the perimeter 84 of a circular exclusion zone 86. The exclusion zone 86 is an area of the protective cover 50 that, when the case 10 is attached to the mobile device, overlays one or more electronic components in the mobile device that are sensitive to magnetic flux or magnetic fields, and/or conductive materials. For example, in this example, the circular exclusion zone 86 represents a position of a wireless charging coil of the specific mobile device for which the case 10 is designed. Providing such an exclusion zone minimises interference by the case when the device is charging wirelessly.

Moreover, it can be seen that the Halbach arrays 72 are equally spaced at 90 degree intervals around the perimeter 84. The Halbach arrays 72 are also provided as two pairs of Halbach arrays. The Halbach arrays 72 of each pair of Halbach arrays are diametrically opposite one another, in the plane of the case or exclusion zone. The two diameters 88, 89 linking each pair are therefore perpendicular to one another. In addition to being perpendicular to one another, the diameters 88, 89 are also provided at 45 degrees to the sides or central axes of the protective cover 50, for optimal placement of the Halbach arrays 72 on the perimeter 84. The Halbach arrays 72 are also angled to lie on tangents of the perimeter 84, so being perpendicular to their respective diameter 88, 89.

Such an arrangement of Halbach arrays 72 is a generally optimal placement of arrays and permits connection of accessories in any of four different configurations.

Although a specific embodiment is presented above in relation to Figures 1 to 6, in other embodiments, other attachment means, protective covers, or coupling means may be provided. For example, the protective cover 50 may be arranged as shown in Figure 7. In this Figure, the layers and their purposes are generally the same to those of Figure 3. However, in this embodiment the mount 76 comprises tabs 92 extending laterally from the base of the mount 76. The protective cover 50, namely the support structure 62, comprises corresponding stops 94 that lie against each tab 92 to prevent movement of the mount 76 in the direction of the front surface 54.

This arrangement ensures that the Halbach array 72, mount 76, or plate 58 cannot be removed from the case 10 if a particularly strong magnetic connection is achieved, because the removal of the Halbach array 72 from the support structure 62 is prevented by the interaction of the tabs 92 and stops 94. Such an arrangement may also be used in accessories for use with the case as noted below.

In some embodiments, the mount may be a metal plate that does not cover the sides of the Halbach array. In some embodiments, one or more Halbach arrays may be included rather than the four Halbach arrays provided in the embodiment of the Figures. In some embodiments, the Halbach arrays may be provided directly onto the stiffening layer, without a mount. In some embodiments the stiffening layer may be integral with the support structure.

Although not shown in the Figures, this disclosure also relates to accessories for use with the case described above. For example, accessories may comprise removable wallets, wall or car vent mounts, wireless chargers, stands, trays, speakers, or power packs. The accessory typically comprises a supporting structure, which may be similar to or different to the support structure or protective cover of the case. The supporting structure holds an accessory coupling means for removably connecting the accessory to the front surface of the protective cover. The accessory coupling means comprises a plurality of permanent magnets arranged to form a Halbach array configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface of the protective cover when the accessory is connected to the case. The Halbach arrays may be provided in a mount as discussed above, and the mount may include tabs as shown in relation to Figure 7.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS1. A case for a mobile device, the case comprising: attachment means for attaching the case to the mobile device; a protective cover comprising front and back surfaces, the protective cover being arranged such that the back surface is adjacent a rear surface of the mobile device when the case is attached to the mobile device; and coupling means located between the front and back surfaces of the protective cover for removably connecting accessories to the case, wherein the coupling means comprises a plurality of permanent magnets arranged to form a Halbach array configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface of the protective cover and to substantially cancel the magnetic field in the direction of the back surface of the protective cover.
2. The case according to claim 1, wherein the coupling means comprises a mount to which the Halbach array is secured, the mount comprising a base provided between the Halbach array and the back surface of the protective cover.
3. The case according to claim 2, wherein the mount comprises a recess in which the Halbach array is received.
4. The case according to claim 2 or 3, wherein the mount comprises a tab extending laterally from the base and wherein the protective cover comprises a stop that lies against the tab to prevent movement of the mount.
5. The case according to any one of claims 2 to 4, wherein the mount is fixed to the back surface of the protective cover.
6. The case according to any one of claims 2 to 5, wherein the mount is formed of metal.
7. The case according to any one of claims 1 to 6, wherein the plurality of permanent magnets is arranged to form a plurality of Halbach arrays.
8. The case according to claim 7, wherein the plurality of Halbach arrays are positioned outside a perimeter of an exclusion zone, the exclusion zone representing an area of the protective cover that overlays one or more electronic components in the mobile device that are sensitive to magnetic flux and/or conductive materials when the case is attached to the mobile device.
9. The case according to claim 8, wherein the plurality of Halbach arrays are spaced around the perimeter of the exclusion zone.
10. The case according to claim 9, wherein the exclusion zone is circular and the plurality of Halbach arrays are arranged into two pairs of Halbach arrays, one Halbach array of each pair of Halbach arrays being diametrically opposite the other Halbach array of each pair of Halbach arrays.
11. The case according to claim 10, wherein the Halbach arrays of the two pairs of Halbach arrays are spaced around the perimeter of the circular exclusion zone at 90 degree intervals.
12. The case according to any one of claims 1 to 11, wherein the front surface of the protective cover is partially defined by a plate, and wherein the Halbach array abuts the plate.
13. The case according to any one of claims 1 to 12, wherein the protective cover comprises a support structure, the coupling means being received in an opening of the support structure.
14. The case according to claim 13, wherein the support structure is disposed between the front and back surfaces.
15. The case according to claim 13 or 14, wherein the thickness of the support structure is substantially equal to the thickness of the coupling means.
16. The case according to any one of claims 1 to 15, wherein the protective cover comprises a stiffening layer, and wherein the coupling means is attached to the stiffening layer.
17. The case according to any one of claims 1 to 16, wherein the protective cover comprises a cushioning layer that defines the back surface of the protective cover.
18. The case according to claim 17, wherein the cushioning layer is formed of a microfibre material. 10
19. An accessory for attaching to the case of any of claims 1 to 18, the accessory comprising a supporting structure holding a coupling means for removably connecting the accessory to the front surface of the protective cover, wherein the coupling means comprises a plurality of permanent magnets arranged to form a Halbach array configured to augment a magnetic field produced by the plurality of permanent magnets in the direction of the front surface of the protective cover when the accessory is connected to the case.
20. A kit of parts comprising the accessory according to claim 19 and the case according to any one of claims 1 to 18