Apparatus and method for fitting bedsheet

Abstract

An apparatus for fitting a bedsheet (6, Figure 1) to a mattress (4, Figure 1) comprises at least one retaining mechanism (8, Figure 4). The retaining mechanism comprises a body 10 comprising a channel 9 for receiving an edge of the bedsheet at an opening of the channel, and a gripping mechanism 12 within the body configured to grip the edge of the bedsheet in the channel. The gripping mechanism is moveable along an axis of the channel in a direction towards the opening of the channel, movement of the gripping mechanism is biased into the channel away from the opening of the channel, and the gripping mechanism is configured to release its grip when positioned at a maximum extent in the direction towards the opening of the channel. The gripping mechanism may comprise at least one biased jaw 22 and may be biased away from the opening of the channel by an elastically deformable member 38. The gripping mechanism may comprise a pinion gear 24, and the body may comprise a corresponding linear gear 26. Methods of fitting and removing a bedsheet to / from a mattress using the apparatus are also disclosed.

Description

The present technique relates to the field of fitting bedsheets to mattresses. Bedsheets are widely used to cover and protect mattresses on beds. Different varieties of bedsheets may be provided, including fitted bedsheets and flat bedsheets, but the different varieties of bedsheet are typically held in place on a mattress in substantially the same way, with the bedsheet held in place by tucking edges of the bedsheet underneath the mattress. Removing a bedsheet and fitting a replacement bedsheet therefore typically involves lifting a mattress up off a bed so that a previous bedsheet can be removed, and so edges of a replacement bedsheet can be tucked underneath the mattress. However, it has been realised that it can often be difficult and sometimes dangerous to change bedsheets in this way, with particular difficulties being presented to those with reduced physical ability, such as the elderly, and those who frequently change bedsheets, such as housekeepers and nursing staff. It would be desirable to provide a technique which enables bedsheets to be fitted to a mattress in an easier and safer way. Viewed from a first aspect, the present technique provides an apparatus for fitting a bedsheet to a mattress, comprising: at least one retaining mechanism comprising: a body comprising a channel for receiving an edge of the bedsheet at an opening of the channel; and a gripping mechanism within the body configured to grip the edge of the bedsheet in the channel; wherein: the gripping mechanism is moveable along an axis of the channel in a direction towards the opening of the channel; movement of the gripping mechanism is biased into the channel away from the opening of the channel; and the gripping mechanism is configured to release its grip when positioned at a maximum extent in the direction towards the opening of the channel. Viewed from a further aspect, the present technique provides a method of fitting a bedsheet to a mattress using the apparatus according to the first aspect as described above, the method comprising: inserting an edge of the bedsheet into the channel of a given retaining mechanism; and gripping the edge of the bedsheet with the gripping mechanism within the body of the given retaining mechanism. Viewed from a yet further aspect, the present technique provides a method of removing a bedsheet from a mattress using the apparatus according to the first aspect as described above, wherein an edge of the bedsheet is held in a given retaining mechanism, the method comprising: pulling the bedsheet to cause the edge of the bedsheet held in the gripping mechanism to move in a direction towards the opening of the channel; and causing the gripping mechanism to reach the maximum extent in the direction towards the opening of the channel and release its grip on the edge of the bedsheet. Further aspects, features and advantages of the present technique will be apparent from the following description of examples, which is to be read in conjunction with the accompanying drawings, in which: Figure 1 illustrates a bed on which a mattress is arranged, suitable for installation of a bedsheet according to the present technique. Figure 2 illustrates a mattress and a plurality of retaining mechanisms according to the present technique in a vertical orientation. Figure 3 illustrates a mattress and a plurality of retaining mechanisms according to the present technique in a horizontal orientation. Figure 4 illustrates an isometric view of a retaining mechanism according to the present technique. Figure 5 illustrates an isometric view of a gripping mechanism according to the present technique. Figure 6 is an exploded diagram illustrating components of a retaining mechanism according to the present technique. Figure 7 illustrates a section view of a retaining mechanism according to the present technique. Figure 8 illustrates a plan view of a retaining mechanism according to the present technique. Figures 9 and 10 illustrate connecting portions according to the present technique. Figure 11 illustrates a section view of an edge of a bedsheet which may be used with a retaining mechanism of the present technique. Part of the reason that there are many issues associated with lifting a mattress to change bedsheets is that the centre of gravity where a person changing a bedsheet is standing is not aligned with the vertical plane of the lift centre, which results in the person lifting a mattress to change the bedsheet having to bend their back and consequently their spine to lift the mattress. Supporting the heavy mattress in this way therefore puts an increased force upon the vertebra and the surrounding tissues and muscles, which can lead to injury. In addition, a mattress is typically lifted with one hand whilst the other hand is used to remove the old bedsheet or tuck the new bedsheet under the mattress. This asymmetrical lifting process causes the weight of the mattress to be offset from the lifting person’s spine, which can cause rotation of the spine and hips which exaggerates the risk of injury. As previously mentioned, persons of older age are especially exposed to injury when attempting to change sheets in this way, and often require assistance to change their sheets due to the risk of injury or a lack of strength. This can affect the elderly person’s ability to be independent. Similar issues arise for those who are less physically able for reasons other than age, where the difficulty in changing a bedsheet can affect that person’s independence. Additionally, medical staff and house keepers are subjected to higher frequencies of lifting mattresses and so suffer an elevated incidence of injury compared to the general population. Providing an apparatus which enables a bedsheet to be fitted without requiring a mattress to be lifted can therefore provide significant benefits. However, the inventor has recognised that certain ways that this can be achieved are unsuitable. For example, in one comparative example a bedsheet may be fitted to a mattress using fixed fasteners such as hook-and-loop fasteners. However, when a person uses a mattress covered by a bedsheet their weight and movement typically deforms the mattress and applies force on the edges of the bedsheet. This force can cause fixed fasteners to become undone, and / or cause damage to the fasteners. If slack were provided in the bedsheet to account for the user’s weight and movement, then the bedsheet would fit loosely to the mattress, and bunching of the bedsheet could occur leading to loss of comfort for the user. The present technique has been made in view of these problems, and seeks to provide an improved apparatus and method for fitting a bedsheet to a mattress. In particular, the present technique allows a bedsheet to be fitted to and removed from a mattress without requiring the mattress to be lifted, and accounts for the weight and movement of a user of the mattress. In one example, the apparatus comprises at least one retaining mechanism for gripping an edge of a bedsheet and providing a retaining force for holding the bedsheet on a mattress. The retaining mechanism comprises a body comprising a channel for receiving an edge of the bedsheet at an opening of the channel. It will be appreciated that whilst reference is made to an edge of the bedsheet, this is to be interpreted as a region of the bedsheet towards an edge of the bedsheet when that bedsheet is fitted to a mattress, and does not strictly have to be the very edge of a bedsheet. For example, an edge of a folded bedsheet may be created by folding part of a flat bedsheet, so the edge of the bedsheet in use could correspond to a central part of the bedsheet when the bedsheet has not been folded to form said edge. Functionally, an edge of the bedsheet is part of the bedsheet which is located at the periphery of the mattress when the bedsheet is installed on the mattress, and therefore is a part of the bedsheet which can be used to secure the bedsheet to a mattress without interfering with the central part of the bedsheet where a user may lie. The channel may pass through the body of the retaining mechanism, such that the edge of the bedsheet can be accommodated within the body of the retaining mechanism. The retaining mechanism also comprises a gripping mechanism. The gripping mechanism is provided within the body of the retaining mechanism and is configured to grip the edge of the bedsheet in the channel. For example, the gripping mechanism may grip the bedsheet in response to the edge of the bedsheet being inserted into the channel. By providing a retaining mechanism comprising a channel, and a gripping mechanism within said channel to grip an edge of a bedsheet, the apparatus can be used to secure a bedsheet to a mattress without requiring the mattress to be lifted. For example, the retaining mechanism could be installed at the edge of a mattress, and the bedsheet could be fitted to the mattress by inserting an edge of the bedsheet into the channel of the retaining mechanism without moving the mattress. The gripping mechanism is moveable within the channel of the retaining mechanism. In particular, the gripping mechanism is moveable along an axis of the channel in a direction towards the opening of the channel. For example, the axis along which the gripping mechanism is moveable may align with the direction in which an edge of the bedsheet is primarily pulled by the weight and movement of a user lying on the mattress (this direction typically being along the same axis as the direction that the bedsheet is installed). By being moveable in the direction towards the opening of the channel, the gripping mechanism is able to move to accommodate the forces exerted on the edge of a bedsheet in use, the movement allowing the gripping mechanism to maintain a grip on the edge of the bedsheet whilst reducing the likelihood of the gripping force being overcome by the force being exerted on the edge of the bedsheet, and reducing the likelihood of the gripping mechanism being damaged. The gripping mechanism is biased into the channel away from the opening. Hence, the gripping mechanism exerts a force on the edge of the bedsheet in the same direction in which the bedsheet is inserted into the retaining mechanism. This force may contribute to keeping the bedsheet taut when fitted to the mattress. Even when the gripping mechanism moves to accommodate movement of a user on the mattress, when the force causing the gripping mechanism to be moved is released, the gripping mechanism can return to a previous position in which it retains the edge of the bedsheet in a position providing tension to the bedsheet on the mattress. In addition, the gripping mechanism is configured to release its grip on the edge of the bedsheet when the gripping mechanism is positioned at a maximum extend in the direction towards the opening of the channel. The distance of travel before the gripping mechanism reaches its maximum extent is not limited but may be chosen such that the maximum extent is not typically reached during normal use of the mattress and therefore the grip is not released in normal use. By enabling the grip to be released at a maximum extent, then removal of the bedsheet from the mattress can be made simple, as the bedsheet only needs to be pulled out of the retaining mechanism, and importantly the mattress does not need to be lifted to enable the bedsheet to be removed. Configuring the gripping mechanism to release at its maximum extent can also reduce the likelihood of damage to the gripping mechanism caused by the gripping mechanism being tugged too sharply by the edge of the bedsheet, because the grip is released when the travel of the gripping mechanism (which would otherwise reduce the likelihood of damage to the gripping mechanism) runs out. A retaining mechanism configured as described above therefore enables a bedsheet to be fitted to and removed from a mattress without lifting the mattress, maintains tension in the bedsheet, and accommodates movement of the bedsheet whilst fitted to a mattress. The manner in which the gripping mechanism grips the edge of the bedsheet is not particularly limited. Desirable properties of the gripping mechanism are that a bedsheet can be easily installed in the gripping mechanism and that the gripping mechanism can quickly release the edge of the bedsheet at the maximum extent. Various configurations of biased jaw-like gripping mechanisms may provide these properties, in which the grip is provided by one or more jaws which are biased into the centre of the channel, for example in a direction perpendicular to the axis of movement of the gripping mechanism. The one or more jaws can be forced open by an edge of a bedsheet when the bedsheet is inserted into the channel, and thereafter the biasing of the one or more jaws can cause the bedsheet to be gripped by the one or more jaws. The one or more jaws may have an edge for gripping the bedsheet, the edge optionally being provided with a surface for increasing friction with the bedsheet, such as a serrated surface. In some examples, a biased jaw could take the form of a biased cam. One jaw may be provided in some examples, in which the single jaw grips the edge of the bedsheet by urging the edge of the bedsheet against a fixed part of the gripping mechanism and thereby providing the necessary friction to grip the edge of the bedsheet. In other examples, two jaws could be provided and arranged to be biased into each other to pinch the edge of the bedsheet between the two jaws to grip the bedsheet. The provision of two jaws may be particularly helpful in cases where the edge of the bedsheet is provided by a folded bedsheet, as in these cases holding only one side of the edge of the bedsheet with a single jaw could allow the two sides of the edge of the bedsheet to slide over each other (one side not being restrained by a jaw) and become released from the gripping mechanism. The gripping mechanism is configured to move towards the opening of the channel in the retaining mechanism. In some examples, the gripping mechanism could move in other directions as well, such as in a direction parallel to an edge of the bedsheet to accommodate movement of the edge of the bedsheet in more than one direction. However, it has been recognised that the majority of force on the edge of the bedsheet in use is in a single direction, and therefore the retaining mechanism can be made substantially simpler by constraining movement of the gripping mechanism to move linearly along the axis of the channel in the direction towards the opening of the channel. For example, the gripping mechanism could be connected to the body via a track enabling the gripping mechanism to move only in one direction. The manner in which the gripping mechanism is biased away from the opening of the channel is also not particularly limited. In some examples, the orientation of the retaining mechanism in use could be such that the axis of movement of the gripping mechanism is vertical with respect to the mattress (i.e., orthogonal to the plane of the mattress, the axis of movement aligning with the force of gravity), and such that the direction in which the gripping mechanism is biased is vertically down. In such examples the biasing could be provided by the weight of the gripping mechanism. In other examples, especially when it is envisaged that the retaining mechanism may be used in a different orientation, an elastically deformable member could be used to bias the movement of the gripping mechanism into the channel. For example, such an elastically deformable member could be connected between the gripping mechanism and part of the body near the opening of the channel, and could urge the gripping mechanism away from the opening. Similarly, the elastically deformable member could be connected between the gripping mechanism and part of the body near the base of the channel away from the opening and urge the gripping mechanism towards the base of the channel. The elastically deformable member could be provided, for example, by a spring such as a metallic spring, or by a rubber block or band. An elastically deformable member provides a reliable method for biasing the movement of the gripping mechanism which does not depend on an orientation of the retaining mechanism. The configuration by which the gripping mechanism releases its grip in response to reaching a maximum extent in the direction towards the opening of the channel is also not particularly limited, and several techniques could be used to achieve this behaviour. In one example where the gripping mechanism comprises one or more jaws to hold the edge of the bedsheet, the configuration of the gripping mechanism could be such that the distance of one or more of the jaws from the centre of the channel increases as the gripping mechanism moves towards the opening of the channel (e.g., if a part of the gripping mechanism mounting a jaw moves along a direction inclined with respect to the channel), such that there is a point at the maximum extent at which the jaw is too far from the centre of the channel to grip the bedsheet and the bedsheet is released. In other examples, a fixed part could be provided in the channel and caused to interact with the gripping mechanism when the gripping mechanism reaches its maximum extent to cause the gripping mechanism to release. For example, a fixed part could push or pull an end of a jaw of the gripping mechanism when the gripping mechanism reaches its maximum extent to cause the jaw to open and release the bedsheet. In one particularly effective example, which does not require any parts to potentially get in the way of the channel and provides a particularly resilient configuration which is suitable for frequent reuse, the gripping mechanism may comprise a pinion gear and the body may comprise a linear gear located to interact with the pinion gear when the gripping mechanism reaches its maximum extent in the direction towards the opening of the channel. Upon the gripping mechanism reaching the maximum extent in the direction towards the opening of the channel, the pinion gear of the gripping mechanism may reach and engage with the linear gear, converting the linear motion of the gripping mechanism in the direction towards the opening of the channel into rotational motion of the pinion gear. The rotational motion of the pinion gear could then be arranged to cause the gripping mechanism to release its grip. For example, when the gripping mechanism comprises one or more biased jaws, the pinion gear could be coupled to one or more jaws and the rotation of the pinion gear could cause said one or more jaws to rotate and thereby release the grip on the bedsheet. In such examples, the linear gear could be an integral part of the body of the retaining mechanism. However, manufacturing the body to have a linear gear integrally formed within the channel (such as on an internal face of the body) may be difficult to achieve in practice. Therefore, in some examples, the body comprises an insert separate from a main part of the body forming the channel, and the insert comprises the linear gear. Therefore, the linear gear can be manufactured more easily on the separate insert outside of the body, and then during manufacturing the insert and therefore the linear gear can be rigidly attached within the body. In addition to simplifying the manufacturing process, this can also allow improved maintenance of the retaining mechanism. For example, if over time the linear gear became worn from repeated engagement with the pinion gear, then rather than replacing the entire body the insert alone could be replaced, simplifying the maintenance procedure and reducing both waste and cost of maintenance. In some examples, the opening of the channel in which the edge of the bedsheet is inserted may comprise at least one rounded portion. The at least one rounded portion could be provided to guide an edge of the bedsheet into the channel, enabling the bedsheet to be inserted into the retaining mechanism more easily and therefore increase the ease by which a bedsheet can be fitted to a mattress. In some examples, rounded portions could be provided on both sides of the channel. The rounded portions, similarly to the linear gear, could be provided on inserts for simplified manufacturing of the retaining mechanism. In some examples, the body of the retaining mechanism comprises two body portions connected at a base, wherein the channel extends between the two body portions, and the opening of the channel and the base are at opposite sides of the body. The channel may also have side openings between the body portions between the opening and base through which the edge of the bedsheet may extend when the bedsheet is held in the gripping mechanism within the channel. The apparatus may comprise a plurality of the retaining mechanisms described above arranged to each grip an edge of the bedsheet whilst the bedsheet is fitted to a mattress. For example, the plurality of retaining mechanisms could be provided around the periphery of a mattress to hold in several places the edge of the bedsheet and therefore firmly fit the bedsheet to the mattress. It will be appreciated that the number of retaining mechanisms is not limited and may depend on a variety of factors including the size of the mattress (with larger mattresses typically requiring a larger number of retaining mechanisms) and a type of bedsheet (more rigid bedsheets may require fewer retaining mechanisms to maintain the desired level of tension). The plurality of retaining mechanisms could in some examples be connected together, although it will be appreciated that this is not a requirement. In examples where the retaining mechanisms are connected, they could for example be attached to a frame for fitting to a bed, onto which a mattress could be installed, with the frame holding the retaining mechanisms in relative positions with respect to each other and with respect to the mattress. In other examples discussed below the retaining mechanisms could alternatively be mounted to a bed frame, or in some examples the retaining mechanisms could be attached to the mattress itself. It will be appreciated that in all of these configurations the retaining mechanisms can be mounted around the periphery of a mattress in positions suitable for holding a bedsheet to a mattress. In some examples, the retaining mechanisms could be arranged such that the movement axes of their gripping mechanisms are aligned with each other and align with a vertical direction of the mattress, orthogonal to the plane of the mattress. In this vertical configuration the retaining mechanisms may be provided around the outside edge of the mattress, and may be easily accessible to a person wishing to fit the bedsheet into the retaining mechanisms. In this configuration the movement axes of the gripping mechanisms is vertical, such that when a person lies on the bed and their weight or movement causes the edges of the bedsheet to be moved vertically (i.e., pulled upwards) then this movement can be accommodated by the vertical movement of the gripping mechanism. The heights of the retaining mechanisms with respect to the mattress are not particularly limited. In some examples the retaining mechanisms could be provided at the same height with, for example, their openings aligning with the lower edge of the mattress. In other examples the openings could align with an upper edge of the mattress, in any position between the upper and lower edges of the mattress, or even at a height not aligning with any part of the mattress. In other examples, the retaining mechanisms may not be provided at the same height as each other with respect to the mattress (their height in the vertical direction being their position along the axis aligned with the movement axis of their gripping mechanisms). For example, side edges (and sometimes the foot edge) of a mattress may be more exposed than a head edge of the mattress when installed on some bed frames having a headboard. To allow easier access to the less exposed edges of the mattress for inserting the edge of the bedsheet, the retaining mechanisms at the less exposed edges of the mattress may be provided at higher positions, whilst retaining mechanisms on more exposed edges may be provided at lower positions so that they are more out of the way and both less visible and less likely to provide an obstacle to a person getting onto the mattress or moving around on the mattress. In some examples, the retaining mechanisms could be arranged such that the movement axes of the gripping mechanisms of at least two of the retaining mechanisms are not aligned with each other, and lie in a plane. For example, at least some of the plurality of retaining mechanisms may lie horizontally in a plane below a mattress to which the bedsheet is to be installed. In this way, the plurality of retaining mechanisms may be largely hidden below the mattress and therefore provide less of an obstacle to users of the bed. The retaining mechanisms may be arranged such that whilst lying in the plane below the mattress the openings of the channels face outwards from the mattress, enabling the edge of the bedsheet to be installed into the retaining mechanisms. In some examples, the apparatus further comprises at least one connecting piece arranged between at least one pair of retaining mechanisms, each connecting piece comprising a connecting channel aligned with the channel in each retaining mechanism of a corresponding pair of retaining mechanisms. For example, the connecting piece may take the form of a body comprising an elongate channel generally matching the cross section of the channel in each retaining mechanism. The connecting piece could be rigid or flexible, with flexible examples enabling the connecting piece to connect retaining mechanisms on different sides of a mattress by flexing around a corner of the mattress. The one or more connecting pieces may be provided to cover the edge of the bedsheet whilst installed on the mattress. This could, for example, prevent the edge of the bedsheet from being caught and accidentally removed from the mattress by a person using the mattress. The one or more connecting pieces may also guide the edge of the bedsheet for easier installation on the mattress, and in some examples could provide a means for mounting the plurality of retaining mechanisms. As mentioned above, in some examples the apparatus may comprise a bed frame, wherein the plurality of the retaining mechanisms is installed on the bed frame and the plurality of the retaining mechanisms is arranged to grip an edge of the bedsheet whilst the bedsheet is fitted to a mattress arranged in the bed frame. Particular examples will now be described with reference to the Figures. Figure 1 illustrates a bed 2 on which a mattress 4 is arranged. As discussed above, typically the mattress 4 must be lifted up off the bed 2 to allow a bedsheet to be changed. The present technique provides an apparatus which enables a bedsheet 6 to be fitted to a mattress 4 without requiring the mattress 4 to be lifted. In particular, at least one retaining mechanism 8 may be provided to enable the bedsheet 6 to be fitted to the mattress 4 by retaining an edge of the bedsheet 6 at the periphery of the mattress 4, therefore meaning that the bedsheet does not need to be held in place in a way which requires the mattress to be lifted, such as tucking the bedsheet under the mattress. Figures 2 and 3 illustrate example arrangements including a plurality of retaining mechanisms 8 for fitting a bedsheet 6 to a mattress 4. An example of a retaining mechanism 8 according to the present technique is illustrated in Figures 4 to 8. Figure 4 is an isometric view of an example retaining mechanism 8. As described above, it will be appreciated that this is only a single example of a retaining mechanism according to the present technique, and other configurations are possible. The illustrated retaining mechanism comprises two body portions 50 and 52, between which extends a channel 9. The channel has an opening 54 and a base 56 at opposite ends of the channel. Edges of the channel extend through the body of the retaining mechanism. The opening 54 of the channel 9 is for receiving an edge of a bedsheet which can be inserted into the channel. In the orientation shown in the example of Figure 4, the edge of the bedsheet is received from the top of the retaining mechanism down into the retaining mechanism. When inserted in the channel, the bedsheet extends through the channel 9 through the edges of the channel. Within the body of the retaining mechanism 8 is a gripping mechanism 12 as illustrated in isometric view in Figure 5. The gripping mechanism 12 is arranged to grip an edge of the bedsheet when it is inserted into the channel 9 sufficiently far to reach the gripping mechanism 12. A method for fitting a bedsheet to the mattress therefore comprises inserting an edge of the bedsheet 6 into the channel 9 of a given retaining mechanism 8, and causing the gripping mechanism 12 to grip the edge of the bedsheet 6 within the channel 9. The bedsheet may be inserted into each of a plurality of retaining mechanisms located around the periphery of the mattress to hold the bedsheet in place around each side of the mattress. In this way, a bedsheet 6 may be fitted to a mattress 4 without requiring the mattress 4 to be lifted. The gripping mechanism 12 is moveable within the body of the retaining mechanism 8 in a direction between the base 56 of the channel and the opening 54 of the channel (vertically in the example of Figure 4). As the gripping mechanism 12 is moveable in the channel 9, then if movement of a user causes an edge of the bedsheet to be tugged during use of the bedsheet 6, this movement can be accommodated by movement of the gripping mechanism. In this way, because the bedsheet is allowed to move around to accommodate movement of the user, less force is applied to the gripping mechanism than if the gripping mechanism were fixed and therefore for a given gripping mechanism the bedsheet can be retained in response to greater forces on the bedsheet. The gripping mechanism 12 is biased towards the base 56 of the channel and away from the opening 54 of the channel. This means that upon release of the force causing the bedsheet (and therefore the gripping mechanism 12) to be displaced, such as when a user gets off the mattress, the gripping mechanism 12 can return to its original position and therefore retighten the bedsheet. The gripping mechanism 12 is arranged to release the bedsheet when the gripping mechanism 12 is moved to a maximum extent towards the opening 54 of the channel. This enables the bedsheet to be removed from the retaining mechanism 8, and therefore from the mattress 4, by pulling the bedsheet to cause the edge of the bedsheet held in the gripping mechanism to move in a direction towards the opening of the channel, and causing the gripping mechanism to reach the maximum extent in the direction towards the opening of the channel and release its grip on the edge of the bedsheet. In this way, the bedsheet 6 can be removed from the mattress without lifting the mattress. The retaining mechanism also enables bedsheets to be installed and removed without requiring any access to part of the mattress below the bed frame. When lifting a mattress to change a bed sheet, a person may need to insert their fingers into the narrow space between the mattress and bed frame to lift the mattress, which may present a difficulty for some users. However, this is not required when the retaining mechanism as described above is used. Figure 6 illustrates an exploded view of the retaining mechanism of Figure 4. The retaining mechanism comprises a body 10 comprising the channel 9. The body 10 is hollow, and the cavity within the body is of sufficient size to accommodate the gripping mechanism 12. The gripping mechanism 12 comprises a gripping body 20. The gripping body comprises a gripping channel which aligns with the channel 9 of the body 10. When the sheet is inserted into the retaining mechanism 8 and gripped by the gripping mechanism 12, it may lie in both the channel 9 of the body 10 and the channel of the gripping body 20. The retaining mechanism 12 also comprises a jaw 22 biased into the centre of the channel via a spring 30. The jaw 22 is displaced against the force of spring 30 when the edge of a bedsheet is inserted into the gripping mechanism 12, and thereafter grips the edge of the bedsheet inserted into the channel 9 by holding the bedsheet between the jaw 22 and an internal face of the channel formed in the gripping body 20 under the effect of the spring 30. The gripping mechanism 12 is biased towards the base of the channel 9 under the effect of an extension spring 38 which is attached between the gripping mechanism 12 and a fixed portion of the retaining mechanism. In the example of Figure 6, the spring 38 is attached to a base cap 44 which is rigidly attached to the body 10 of the retaining mechanism by screw 40, although it will be appreciated that this is merely illustrative and other arrangements are possible. Rounded portions 14 and 16 may be provided on the body 10 of the retaining mechanism 8. The rounded portions can guide the edge of the bedsheet into the channel 9, and therefore enable easier fitting of a bedsheet 6 to a mattress 4. In the example of Figure 6 the rounded portions 14 and 16 are provided separately from the body as inserts, and are connected to the body 10 in the example of Figure 6 using screws 18. The gripping mechanism 12 also comprises pinion gear 24. Pinion gear 24 engages with a toothed surface of the jaw 22 such that the rotation of the pinion gear 24 and the jaw 22 are coupled. The retaining mechanism 8 comprises a linear gear 26, which may be provided as a lower portion of an insert fitted to the body 10, for example in Figure 6 the linear gear 26 is provided as an extension on insert comprising the rounded portion 14. The linear gear 26 is fixed with respect to the channel 9, and is arranged to engage the pinion gear 24 of the gripping mechanism 12 at the maximum extent of movement of the gripping mechanism 12 in the direction towards the opening 54 of the channel 9. When the gripping mechanism 12 reaches its maximum extent, the pinion gear 54 engages with the linear gear 26 and the linear motion of the gripping mechanism 12 in the direction of the opening 54 is converted into rotational motion of the pinion gear 24, which via its coupling with the jaw 22 causes the jaw 22 to rotate. Rotation of the jaw 22 causes the gripping surface of the jaw 22 to move away from the centre of the channel and therefore causes the gripping mechanism 12 to release its grip on the edge of the bedsheet. Hence, the bedsheet 6 can be easily removed from the retaining mechanism by pulling the edge of the bedsheet out of the retaining mechanism 8 to cause the gripping mechanism 12 to reach its maximum extent and release the grip on the bedsheet. When the bedsheet is removed from the gripping mechanism 12 at the maximum extent, the gripping mechanism 12 will return to the base of the channel under the effect of the spring 38. Dampening, such as rubber pads 42, may be provided on the base cape 44 to reduce the noise and likelihood of damage when the gripping mechanism 12 returns to the base of the channel. Wheels 28 and 36 may be provided to guide the movement of the gripping mechanism 12 in the body 10 of the retaining mechanism 8. The wheels 28 and 36, pinion gear 24, jaw 22, and spring 38 may be connected to the gripping body 20 via pins 34 passing through the gripping body 20. A further pin may connect the other end of the spring 38 to the base cap 44. Figure 7 illustrates a section view of the assembled retaining mechanism 8, along a direction looking through the channel 9 with the opening 54 at the top and the base 56 at the bottom. The components described above are illustrated, with the gripping mechanism 12 at its furthest extent towards the base 56 of the channel, which may be the position of the gripping mechanism 12 before a bedsheet 6 has been inserted into the channel 9. Figure 8 is a plan view of the retaining mechanism 8, showing rounded portions 14 and 16, and the opening 54 of the channel 9 between the rounded portions. Returning to Figure 2, an example is illustrated in which a plurality of retaining mechanisms 8 are installed in a vertical orientation around the periphery of a mattress 4. An isometric view and a section view of the installation are shown. In the vertical orientation, the movement of the gripping mechanisms 12 in each of the retaining mechanisms 8 are aligned, and are orthogonal to the plane of the mattress 4. The opening 54 of the channel in each retaining mechanism 8 may be provided on the top side, to enable the bedsheet to be inserted into the retaining mechanisms. The plurality of retaining mechanisms may be mounted to a bed 2 on which the mattress 4 is installed, connected to the mattress 4 itself, or connected together on a frame as shown in Figure 2 which is independent from both the bed 2 and mattress 4. It will be appreciated that other configurations are possible. As shown in Figure 2, the retaining mechanisms may be provided at different heights. This can allow retaining mechanisms at regions of the bed which are harder to access, such as the headboard, to be more exposed and therefore easier to access for inserting the edge of the bedsheet. Figure 3 illustrates an alternative arrangement in which the plurality of retaining mechanisms 8 are installed in a horizontal orientation below the mattress 4, with their openings 54 arranged on the outer edge of the mattress. In this orientation, the retaining mechanisms can still allow a bedsheet to be installed without lifting the mattress 4 in circumstances where edges of the bed are exposed. It will be appreciated that examples could be provided where retaining mechanisms 8 are provided in mixed configurations of both horizontal and vertical retaining mechanisms 8, and in some examples may also take an orientation which is neither horizontal nor vertical. In both Figures 2 and 3, movement directions of the gripping mechanisms 12 are illustrated with arrows. It will be appreciated that the movement in the indicated directions permits an edge of the bedsheet to move to accommodate the movement and weight of a user lying on the mattress whilst the edge of the bedsheet is retained in the gripping mechanisms 12. Figures 9 and 10 illustrate examples of connecting pieces 60 which may be provided. The connecting pieces 60 could be provided in various different formats. Generally, the connecting piece comprises a retaining channel for receiving an edge of the bedsheet 6 in regions around the periphery of the mattress 4 without retaining mechanisms 8. This can cover the edge of the bedsheet to make accidental removal less likely, and can help to guide the edge of the bedsheet for easier installation. It will be appreciated that provision of the connecting pieces is optional, and the apparatus may be provided with or without the connecting pieces providing the retaining channel in different examples as the functionality of the retaining mechanisms is provided in examples which do not include the connecting pieces. In one example, connecting pieces 60 may be provided between retaining mechanisms 8. Alternatively, the retaining mechanisms 8 may be installed within the channel of a connecting piece. The connecting pieces 60 may be flexible to permit installation of a retaining channel around a corner of the mattress 4. In other examples, various connecting pieces may be rigid and formed to fit corners of the mattress 4. In a yet further example, the connecting pieces may be segmented, and several connecting pieces could be fitted together to enable the channel to be installed around a corner of a mattress as illustrated in Figure 10. In some examples, different predefined segments may be provided which can be combined to fit mattresses of various different sizes. As discussed above, in some examples the retaining mechanisms may be provided at different heights. For compatibility with these examples, in some examples the connecting pieces may have a shape which includes a transition between different heights around the periphery of the mattress to accommodate retaining mechanisms provided at different heights. For example, a connecting piece may be curved along an axis (by having portions with different heights with respect to the axis) which lies in the retaining channel and aligns with the direction in which the bedsheet is inserted and removed from the retaining channel. This is illustrated in Figure 9 where the height of the connecting piece 60 is higher at the head of the mattress when compared to its height at the edges of the mattress, thereby enabling access to the retaining channel at the typically less exposed head of the mattress. Figure 11 illustrates an edge of a bedsheet 6. Whilst it will be appreciated that the retaining mechanisms described above may be used with any conventional bedsheets, Figure 11 illustrates an example bedsheet which may enable improved ease of using the retaining mechanisms 8. In particular, the example bedsheet of Figure 11 comprises a rigid strip 70 at the edge of the bedsheet. The rigid strip 70 may be provided around the entire edge of the bedsheet continually or in sections, or may be provided at certain predetermined regions of the bedsheet (for example at locations corresponding to locations of retaining mechanisms). The rigid strip may provide additional stiffness to portions of the edge of the bedsheet which can enable that portion of the bedsheet to be inserted into the retaining mechanism more easily. For example, the rigid strip 70 could enable the edge of the bedsheet to be inserted into the retaining mechanism by being pushed into the retaining mechanism more easily than a bedsheet without said rigid strip 70. This could be particularly beneficial in examples where the edges of the retaining mechanism are harder to access, such as when the retaining mechanisms are installed below a mattress, and therefore examples when pulling the bedsheet into the retaining mechanism from the sides is more difficult. The rigid strip 70 may in some examples be stiffer in one direction than others. For example, the rigid strip may be stiff in the direction along which it is inserted into the retaining mechanism, which for example could be the vertically up / down direction illustrated in Figure 11, but may be less stiff in other directions such as in the left / right directions illustrated in Figure 11 to allow the bedsheet to be flexible. The rigid strip 70 may for example be provided by a strip of a flexible plastic. The rigid strip 70 may be attached to the bedsheet 6 in various different ways. In one example, the rigid strip could be glued to an edge of a bedsheet. However, it may be preferable for the rigid strip 70 to be removable from the bedsheet to allow the bedsheet to be washed more easily, and therefore in the alternative example illustrated in Figure 11 the rigid strip 70 is held within a cavity formed by folding the edge of the bedsheet. The cavity could for example be made permanent by attaching the folded portion to the bedsheet, or could be temporary without attaching the folded portion to the bedsheet. In the present application, the words “configured to...” are used to mean that an element of an apparatus has a configuration able to carry out the defined operation. In this context, a “configuration” means an arrangement or manner of interconnection of hardware or software. For example, the apparatus may have dedicated hardware which provides the defined operation, or a processor or other processing device may be programmed to perform the function. “Configured to” does not imply that the apparatus element needs to be changed in any way in order to provide the defined operation. In the present application, lists of features preceded with the phrase “at least one of” mean that any one or more of those features can be provided either individually or in combination. For example, “at least one of: [A], [B] and [C]” encompasses any of the following options: A alone (without B or C), B alone (without A or C), C alone (without A or B), A and B in combination (without C), A and C in combination (without B), B and C in combination (without A), or A, B and C in combination. Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as 5 defined by the appended claims.

Claims

1. An apparatus for fitting a bedsheet to a mattress, comprising:at least one retaining mechanism comprising:a body comprising a channel for receiving an edge of the bedsheet at an opening of the channel; anda gripping mechanism within the body configured to grip the edge of the bedsheet in the channel;wherein:the gripping mechanism is moveable along an axis of the channel in a direction towards the opening of the channel;movement of the gripping mechanism is biased into the channel away from the opening of the channel; andthe gripping mechanism is configured to release its grip when positioned at a maximum extent in the direction towards the opening of the channel.

2. The apparatus according to claim 1, wherein the gripping mechanism comprises at least one biased jaw for gripping the edge of the bedsheet in the channel.

3. The apparatus according to any of claim 1 and claim 2, wherein the gripping mechanism is constrained to move linearly along the axis of the channel in the direction towards the opening of the channel.

4. The apparatus according to any preceding claim, wherein the gripping mechanism is biased away from the opening of the channel under the effect of an elastically deformable member.

5. The apparatus according to any preceding claim, wherein the gripping mechanism comprises a pinion gear, and the body comprises a linear gear located in the channel at the maximum extent in the direction towards the opening of the channel;wherein the pinion gear is configured to engage with the linear gear when the gripping mechanism is positioned at the maximum extent in the direction towards the opening of the channel to cause the gripping mechanism to release its grip.

6. The apparatus according to claim 5, whereinengagement of the pinion gear with the linear gear is arranged to cause the pinion gear to rotate, and the gripping mechanism is configured such that rotation of the pinion gear causes the gripping mechanism to release its grip.

7. The apparatus according to any of claim 5 and claim 6, whereinthe body comprises an insert separate from a main part of the body forming the channel, andthe insert comprises the linear gear.

8. The apparatus according to any preceding claim, whereinthe body comprises at least one rounded portion at the opening of the channel configured to guide the edge of the bedsheet into the channel.

9. The apparatus according to any preceding claim, whereinthe body comprises two body portions connected at a base, wherein the channel extends between the body portions, and the opening of the channel and the base are at opposite sides of the body.

10. The apparatus according to any preceding claim, comprising a plurality of the retaining mechanisms arranged to each grip an edge of the bedsheet whilst the bedsheet is fitted to the mattress.

11. The apparatus according to claim 10, wherein the plurality of the retaining mechanisms are arranged such that the movement axes of their gripping mechanisms align with each other and align with a vertical direction of the mattress orthogonal to the plane of the mattress.

12. The apparatus according to claim 11, wherein at least two retaining mechanisms of the plurality of the retaining mechanisms are arranged at different heights with respect to each other in the direction aligned with the movement axes of their gripping mechanisms.

13. The apparatus according to claim 10, wherein the plurality of retaining mechanisms are arranged such that the movement axes of the gripping mechanisms of at least two of the retaining mechanisms are not aligned with each other, and lie in a plane.

14. The apparatus according to any of claims 10 to 13, comprising at least one connecting piece arranged between at least one pair of retaining mechanisms, each connecting piece comprising a connecting channel aligned with the channel in each retaining mechanism of a corresponding pair of retaining mechanisms.

15. The apparatus according to any of claims 10 to 14, comprising a bed frame, wherein the plurality of the retaining mechanisms is installed on the bed frame and the plurality of theretaining mechanisms is arranged to grip an edge of the bedsheet whilst the bedsheet is fitted to a mattress arranged in the bed frame.

16. A method of fitting a bedsheet to a mattress using the apparatus according to any5 preceding claim, the method comprising:inserting an edge of the bedsheet into the channel of a given retaining mechanism; and gripping the edge of the bedsheet with the gripping mechanism within the body of the given retaining mechanism.10 17. A method of removing a bedsheet from a mattress using the apparatus according to anyof claims 1 to 15, wherein an edge of the bedsheet is held in a given retaining mechanism, the method comprising:pulling the bedsheet to cause the edge of the bedsheet held in the gripping mechanism to move in a direction towards the opening of the channel; and15 causing the gripping mechanism to reach the maximum extent in the direction towardsthe opening of the channel and release its grip on the edge of the bedsheet.

Images