Patent Description:
After a surgery, patients in a hospital typically make their first steps in the hospital itself. Especially after surgeries that affect the ability to walk, climbing stairs constitutes a major challenge for patients. To practice walking and climbing stairs, patients usually first walk along the corridor of the hospital and, after a first successful training, up and down the stairway of the building. This is inconvenient in two aspects. First, the stairway of a hospital is a busy place frequented by patients, visitors and staff moving between different stations of the hospital, which creates stress for the patients. Second, this solution is just a provisional one in the sense that the stairway is not built for this purpose and the treads are not designed to match the patients' needs. A considerable disadvantage of using the building stairways as training area is that patients that require assistance cannot profit from existing body weight support systems, which relieve patients from their body weight and further catch them in case they fall.

Some hospitals might have dedicated trainings stairs respectively training steps available; however, they are bulky and thereby require a lot of precious space even when they are not in use.

Furthermore, <CIT> discloses a collapsible table that comprises a plurality of planks. Further, <CIT> discloses a set of stairs having steps which can move upward and/or downward. Furthermore, <CIT> discloses a folding staircase with a wall-mounted stringer. <CIT> discloses a collapsible stair lift having a platform located at the top of the stairs and lowers from the top of the stairs to a position flush with the stairs. Finally, <CIT> discloses a retractable staircase comprising a plurality of movable treads with a slidable guidance unit linking each treads.

Based on this, it is subject of the present invention to provide a staircase which is improved regarding the problems described above.

This objective is solved by a staircase with the features of claim <NUM>.

Advantageous embodiments of the invention are given in the corresponding dependent claims and described in the following.

The invention discloses a modularly extendable staircase comprising a plurality of extendable treads, each tread comprising a tread surface, wherein each tread is configured to be moved from a retracted state to an extended state such that when each tread is arranged in its retracted state, the tread surfaces extend in a common extension plane, and wherein when the respective tread is arranged in an extended state the tread surface of the respective tread extends parallel to and above a tread surface of a neighboring tread, characterized in that the staircase comprises at least one guidance unit arranged at the treads and configured to be slidable between and fixable at at least a first and a second position, wherein the first and second position correspond to the retracted and the extended state of a respective extendable tread, respectively, and wherein the at least one guidance unit is connecting the respective tread with its neighboring treads.

In the context of the present invention, the term 'modularly extendable' or 'modular extension' refers to the possibility to extend or retract individual treads of the staircase, i.e. without the need to extract all extendable treads of the staircase. However, the staircase according to the invention also permits to extend or retract all extendable treads of the staircase. The number of extendable treads is arbitrary. The modular design of the staircase is in particular useful for use in hospitals or rehab institutions, as it permits to select a specific number of extended treads depending on the physical constitution of the patient. The staircase according to the invention may however also find applications in other fields, for example as a compact extendable staircase for use in labs, workshops and the like.

The tread surface refers to the part of the tread a patient or user is stepping on during intended use of the staircase. To this end, the tread surface is preferably arranged horizontally and oriented perpendicular to a vertical gravitational force such that the patient or user does not need to balance or compensate any tilts of the tread surface with respect to a horizontal axis normal to the vertical gravitational force. However, the staircase may also be used on an oblique plane, if the tread surfaces remain normal to the gravitational force.

The invention advantageously proposes to configure the tread surfaces such that they can be moved between a retracted state and an extended state. In the retracted state, the tread surfaces of the extendable treads extend in a common extension plane, making the staircase compact and easy to store, which is particularly useful when the staircase is not in use. When the tread surface of the respective extendable tread is moved to the extended state above the tread surface of the neighboring tread, the staircase may be used as intended.

According to an embodiment of the present invention, the staircase may form a cuboid when all treads are in the retracted state. To this end, all extendable treads may be arranged in a static, particularly non-extendable, lowermost tread. The cuboid may for example have a height H, a width W and a length L, wherein the height extends along a vertical z-axis and the width and length extending along an x- and y- axis in a horizontal plane perpendicular to the vertical z-axis, such that the x-, y- and z-axes span an orthogonal coordinate system. In the following, the terms vertical and horizontal refer to orientations relative to the coordinate system defined here.

The height of the cuboid may correspond to a height of the lowermost tread and the dimensions of the width and length define an area covered by the staircase, particularly covered by the lowermost tread. The dimensions of the cuboid may for example be chosen such that an aspect ratio R = W/L is within <NUM> and <NUM> and that the height H may be within <NUM> and <NUM>. For example, the width may be <NUM>, the length may be <NUM> and the height may be <NUM>. The respective tread surface of a respective tread may for example have a depth between <NUM> and <NUM>, particularly between <NUM> and <NUM>, said depth extending along the length of the staircase, respectively.

Each extendable tread may comprise a tread height that may be on the order of the height of the lowermost tread or lower, for example between <NUM> and <NUM>.

A structure comprising the respective tread surface of a respective tread may comprise a thickness that may be substantially lower than the tread height of the respective tread, i.e. a thickness smaller than <NUM>, particularly smaller than <NUM>.

Each tread of the staircase may for example comprise six pairwise opposing boundaries defining a volume within the boundaries. For example, the volume defined by the lowermost tread may be approximated by the dimensions of the cuboid, H x W x L. The boundaries may for example be formed by walls of the respective tread. The walls may be closed walls, but they also may comprise holes or openings in general. Opposing boundaries or walls may be oriented parallel to each other, but they may also be oriented at a finite angle with respect to each other. The term 'neighboring' refers to adjacent treads of a respective tread. For example, thread three has the neighboring treads two and four.

As described above, the staircase comprises at least one guidance unit that may be configured to move the extendable treads between the retracted and the extended state. To this end, the guidance units may be arranged at the extendable treads and configured to be slidable between and fixable at at least a first and a second position. Preferably, the first and second position may correspond to the retracted and the extended state of a respective extendable tread, respectively.

To move the respective tread surface relative to the tread surfaces of the neighboring treads between the extended and the retracted state, the guidance units may connect the respective extendable tread with its neighboring treads.

According to an embodiment, the at least one respective guidance unit may be arranged for example on two neighboring walls, particularly vertical neighboring walls of neighboring treads, slidably connecting the neighboring treads. However, the at least one guidance unit may also be mounted on an outside and/or an inside of the respective vertical wall.

The at least one guidance unit may be arranged vertically, wherein in the first position the respective tread is in the retracted state and wherein in the second position the respective tread is in the extended state. Preferably, the second position is located vertically above the first position.

According to an embodiment of the present invention, the at least one guidance unit is pivotable around an axis extending within in a horizontal plane spanned by the x- and the y-axis defined above. The axis may for example be parallel to the x-axis or the y-axis, such that the guidance unit may be pivoted around an axis parallel to a front- or backside of the staircase.

According to another embodiment of the present invention, in the first position, the at least one guidance unit may be arranged essentially horizontally (i.e. parallel to the x- and the y-axis) with the respective tread being in the retracted state. Further, in the second position, the at least one guidance unit may be pivoted around said axis relative to the first position such that the respective tread is in the extended state. As such, the guidance units may be movable between the first and second position and pivotable around said axis so as to move the respective tread between the retracted and the extended state.

According to another aspect of the present invention, the treads may comprise support struts. The support struts may advantageously be used to stabilize and fix individual treads, particularly in the extended state. To this end, the support struts may for example be mounted on at least one wall of the respective tread, particularly a vertical wall, particularly an outside and/or an inside of the vertical wall.

According to another embodiment of the present invention, the support struts may be pivotable around at least one respective axis. Said axis is preferably arranged horizontally, particularly parallel to the x-axis. As such, the support struts may form pivotable support struts that may be used to pivot a respective tread between the retracted and the extended state.

According to yet another embodiment of the present invention, the pivotable support struts connect neighboring treads such that the support struts are pivotable around a first pivot axis and around a second pivot axis. Preferably, in this embodiment, the pivot axes are offset and parallel to each other and parallel to the horizontal plane defined by the x- and y-axis, wherein the first pivot axis runs through a respective extendable tread and wherein the second pivot axis runs through a neighboring tread of the respective tread. As such, the two pivot axes may form a lever that may be used to pivot the respective tread surface of the respective tread between the retracted state and the extended state. Preferably, each two of these levers may be arranged on each of two front sides of a respective tread, so as to enable a stable arrangement of the respective tread surface parallel above the neighboring tread surface.

According to another embodiment of the present invention, the pivotable support struts may connect neighboring treads such that they are further pivotable around a third pivot axis parallel to the first and second pivot axes, forming double levers configured to pivot the respective tread surface between the extended and retracted state.

According to another aspect of the present invention, the treads may comprise support blocks. The support blocks may be used to support treads in the extended state by positioning the treads on the support blocks. For example, the neighboring tread may comprise support blocks that may be used to support the extended respective tread. Preferably, the support blocks are used in combination with the guidance units, wherein the guidance units may be used to extend or retract a respective tread and wherein the support blocks are used to support the extended or retracted tread in the extended or retracted state. The support blocks may also be used in combination with the support struts, wherein the support struts may be positioned on the support blocks so as to fix the respective tread in the extended or retracted state.

The support blocks may for example be mounted on at least one vertical wall of the respective tread. Particularly, the support blocks may be mounted on the inside and/or the outside of the respective vertical wall.

Another aspect of the present invention refers to extension elements that may be used to extend the respective tread from the retracted state to the extended state via the guidance units and/or the support struts as well as to retract the respective tread from the extended state to the retracted state via the guidance units and/or the support struts.

For example, the extension elements may comprise recesses arranged on the respective extendable tread area for manual extension of the respective tread from the retracted state to the extended state as well as for manual retraction of the respective tread from the extended state to the retracted state. To this end, the recesses may for example be arranged on the respective tread surfaces or walls of a respective tread.

As another example, the extension elements may comprise a chain controlled by a chain actuator configured to automatically extend the respective tread from the retracted state to the extended state as well as to automatically retract the respective tread from the extended state to the retracted state.

As another example, the extension elements may comprise a linear actuator configured to automatically extend the respective tread from the retracted state to the extended state as well as to automatically retract the respective tread from the extended state to the retracted state.

The linear actuator may further be configured to pivot around a corresponding axis extending along a horizontal axis, particularly an axis parallel to the x-axis. The linear actuator may also be coupled to a lever configured to automatically extend the respective tread from the retracted state to the extended state as well as to automatically retract the respective tread from the extended state to the retracted state.

As yet another example, the extension elements may comprise a scissor lift controlled by a scissor lift actuator configured to automatically extend the nth tread from the retracted state to the extended state as well as to automatically retract the nth tread from the extended state to the retracted state.

In another embodiment of the present invention, the staircase may comprise at least one battery for powering the chain actuator, the linear actuator or the scissor lift actuator. Alternatively or additionally, the staircase may comprise an electrical connection, for example at least one cable configured to be connected to an external power supply for powering the chain actuator, the linear actuator or the scissor lift actuator.

The batteries may be mounted inside the volume defined by the staircase.

Preferably, the batteries may be configured to be automatically recharged via an external power supply.

Another aspect of the present invention refers to locking elements for locking or unlocking the respective tread in the extended or the retracted state.

For example, the locking elements may comprise the pivotable support struts, wherein in the extended state, the pivotable support struts of the respective tread may be arranged vertically and supported by the support blocks of the neighboring tread and wherein in the retracted state, the pivotable support struts of the respective tread may be arranged essentially horizontally, such that the staircase remains compact when all treads are in the retracted state.

While a vertical orientation of the support struts, i.e. parallel to the gravitational force, in this embodiment may be advantageous in the extended state so as to minimize or avoid a tilt caused by a patient or user stepping on the tread surface of an extended tread, the orientation of the support struts in the retracted state may also deviate from a horizontal orientation depending on the constructive details of the staircase.

According to another embodiment of the present invention, the locking elements may comprise the pivotable support struts, wherein in the extended state, the respective tread is pivoted into a position beyond a dead center of the pivotable support struts. As such, the respective tread or tread surface may be supported by the tread area of the neighboring tread in the extended state, wherein in the retracted state, the pivotable support struts are arranged essentially horizontally. By positioning the extended tread or tread surface beyond a dead center of the pivotable support struts, the respective extended tread may be advantageously locked in the extended state by supporting it on a respective lower neighboring tread.

According to an embodiment of the present invention, the pivotable support struts may be formed by at least one of the vertical walls of the respective tread. Preferably, the vertical wall may be arranged at a front side or back side along the length of the staircase, extending along the y-axis. In this embodiment, the respective wall may itself pivotably and arranged essentially vertically in the extended state and non-vertically, particularly essentially horizontally in the retracted state.

According to another example, the locking elements may comprise the double lever, the aforementioned double lever being configured to pivot the respective tread between the extended state and the retracted state.

According to another example, locking elements may comprise the pivotable support struts, wherein in the extended state, the pivotable support struts are arranged vertically such that when the staircase is positioned on a lower positioning surface, the pivotable support struts are supported by the lower positioning surface. In the retracted state, the pivotable support struts may for example be arranged essentially horizontally. In this particular embodiment, the support struts of every tread preferably extend from the extended tread vertically downwards to the lower positioning surface, so as to support the extended tread directly on the lower positioning surface. While a vertical orientation of the support struts in this embodiment may be advantageous in the extended state so as to minimize or avoid a tilt of the respective tread caused by a patient or user stepping on the tread surface of an extended tread, the orientation of the support struts in the retracted state may deviate from a horizontal orientation depending on the constructive details of the staircase.

For example, the locking elements may comprise at least one locking pin.

According to another example, the locking elements may comprise at least one lifting magnet arranged on the treads. Preferably, the lifting magnet is further configured to engage and extract the locking pin so as to lock and unlock a respective tread in the extended or the retracted state.

According to another example, the locking elements may comprise at least one pivoting magnet. Preferably, said pivoting magnet may be equipped with the locking pin and configured to pivot the locking pin around a respective axis so as to lock and unlock the respective tread in the extended or in the retracted state.

According to an embodiment of the present invention, the lifting magnet and/or the pivoting magnet may interact with the aforementioned guidance units such that the lifting magnet or the pivoting magnet may be configured to engage or extract the locking pin into or out of the at least one guidance unit, particularly in an optional through hole of the at least one guidance unit so as to lock the respective tread or tread surface in the extended or the retracted state.

According to another aspect of the invention, the staircase may comprise at least one force sensor configured to determine the force exerted by a patient stepping on the tread surface of a respective tread.

According to another aspect of the invention, the staircase may comprise at least one spring configured to reduce a tilting moment acting on the treads, particularly a tilting moment acting when the respective tread is moved between the retracted and the extended state, i.e. when the respective tread is not locked in the retracted or the extended state by the locking elements. To this end, the at least one spring may be arranged in an edge section of the stepping area so as to reduce or compensate the tilting moment acting on the treads. The at least one spring may extend between next neighboring treads, respectively, so as to reduce the tilting moment between next neighboring treads down to the lower positioning area. The at least one spring may also extend directly from the respective extended tread down to the lower positioning area, so as to directly contact the lower positioning area. In case a plurality of springs is used, different spring constants may be used. In general, the spring constant may be adjusted according to the tilting moment to be compensated.

For example, the at least one spring may comprise or be a pneumatic spring.

According to another aspect of the invention, the staircase may comprise a cover lid configured to cover an upside of the staircase if all treads are in the retracted state. Using the cover lid, the staircase may be closed and safely stored when not in use.

According to yet another aspect of the invention, the staircase may comprise a ramp. Preferably, said ramp is configured to be mounted to an upmost tread of the staircase, such that the ramp connects the lower positioning surface and the tread surface of the upmost tread. The ramp may be advantageously used by a patient to practice walking on an oblique plane in addition to climbing stairs. A pitch angle of the oblique surface comprised by the ramp may be tuned by varying the number of extended treads. In another advantageous embodiment of the present invention, the ramp may comprise the cover lid.

In another aspect of the present invention, the staircase comprises a control unit configured to control the locking elements, and/or extension elements. The control unit may permit automated control over the staircase and particularly the extension, retraction, locking and unlocking of the treads, such that the staircase can be set up automatically, for example by the patient or medical personal.

Another aspect of the invention refers to a method for manual modular unlocking, extension or retraction and locking of a respective tread of the staircase, the method comprising the following steps:.

The term 'modular' refers to the unlocking, extension or retraction and locking of individual treads without the need to unlock, extend or retract and lock all extendable treads.

However, another aspect of the invention refers to a method for manual unlocking, extension or retraction and locking of all extendable treads of the staircase, the method comprising the following steps:.

This method particularly refers to embodiments wherein all extendable treads are connected to neighboring treads via the guidance units, (pivotable) support struts, levers or double levers, such that by exerting a vertically upward or downward force on the upmost tread, all lower treads will follow the respective vertical movement of the upmost tread, since all treads are mutually connected via the guidance units, levers and the like.

Another aspect of the invention refers to a method for automatic modular unlocking, extension or retraction and locking of the respective tread of the staircase, the method comprising the following steps executable by the control unit:.

Another aspect of the invention refers to a method for automatic unlocking, extension or retraction and locking of all extendable treads of the staircase, the method comprising the following steps executable by the control unit:.

Particularly, exemplary embodiments are described below in conjunction with the Figures. The Figures are appended to the claims and are accompanied by text explaining individual features of the shown embodiments and aspects of the present invention. Each individual feature shown in the Figures and/or mentioned in the text of the Figures may be incorporated (also in an isolated fashion) into a claim relating to the device according to the present invention.

According to the invention, a modularly extendable staircase <NUM> comprises a plurality of extendable treads <NUM>, each tread <NUM> comprising a tread surface <NUM>, characterized in that each tread <NUM> is configured to be moved from a retracted state <NUM> to an extended state <NUM> such that when each tread <NUM> is arranged in its retracted state <NUM>, the tread surfaces <NUM> extend in a common extension plane <NUM>, and wherein when the respective tread <NUM> is arranged in an extended state <NUM> the tread surface <NUM> of the respective tread <NUM> extends parallel to and above a tread surface <NUM> of a neighboring tread <NUM>.

<FIG> shows an embodiment for a staircase <NUM> according to the invention. According to this embodiment, the staircase <NUM> may form a cuboid when all treads <NUM> are in the retracted state <NUM>. To this end, all extendable treads <NUM> may be arranged in a static, particularly non-extendable, lowermost tread. The cuboid may for example have a height H, a width W and a length L, wherein the height extends along or parallel to a vertical z-axis and the width and length extending along or parallel to a x- and a y- axis, respectively. The x- and the y-axis are within a horizontal plane perpendicular to the vertical z-axis, such that the x-, y- and z-axes span an orthogonal coordinate system. The terms vertical and horizontal refer to orientations relative to the coordinate system defined here.

The height H of the cuboid may correspond to a height H of a lowermost tread <NUM> and the dimensions of the width and length may define an area covered by the staircase <NUM>, particularly covered by the lowermost tread <NUM>.

The staircase <NUM> shown in <FIG> comprises cuboid treads <NUM> with each six pairwise opposing parallel walls, wherein four of the walls are oriented vertically and two horizontally, with reference to the coordinate system defined above. However, the invention is not limited to cuboid treads <NUM>, such that the walls may for example also be rounded and opposing walls may be tilted at a finite angle relative to each other. Particularly, the walls may also comprise openings, wherein the openings may also cover a majority of a surface of an individual wall, as long as the remaining walls represent sufficient structure to maintain the stability of the staircase <NUM>.

The extendable treads <NUM> of the staircase <NUM> constitute several advantages for a user, particularly for use in a hospital or a clinic. As shown in the embodiment of <FIG>, the staircase <NUM> permits to arrange all extendable treads <NUM> in a volume comprised by the lowermost tread <NUM>, making the staircase <NUM> very compact and easy to store. Particularly, the staircase <NUM> may be small enough to both be stored in the retracted state <NUM> and set up in the extended state <NUM> in a hospital room, i.e. close to the patient, such that the patient does not have to walk to the staircase <NUM>. Second, according to the invention, individual extendable treads <NUM> may be extended modularly, i.e. independently of the other extendable treads <NUM>, such that the number of extended treads <NUM> may be selected according to a training program of a patient.

For example, a low number of treads <NUM> may be selected to start the training and a larger number of treads <NUM> may be selected for an advanced training.

While the example staircase <NUM> shown in <FIG> comprises five treads <NUM>, wherein the last four treads <NUM> are modularly extendable, both the total number of treads <NUM> and the number of extendable treads are arbitrary. In some embodiments (not shown in <FIG>) the staircase <NUM> may also comprise more than one, for example two, three or four treads <NUM> that are not extendable, followed by an arbitrary number of extendable treads <NUM>. In case the staircase <NUM> comprises a set of non-extendable treads <NUM>, the extendable and retractable treads <NUM> may be retractable into a volume defined by the set of not extendable and retractable treads <NUM>.

As shown in <FIG>, individual treads <NUM> may for example have an identical tread <NUM> height, particularly in the extended state <NUM>. The extendable and retractable treads <NUM> may have the same tread <NUM> height as the static, non-extendable treads <NUM>.

When in use, the lowermost tread <NUM> of the staircase <NUM> is preferably positioned on top of a lower positioning surface <NUM>. As shown in the embodiment in <FIG>, both the lower positioning surface <NUM> and the tread surfaces <NUM> may be arranged horizontally and parallel to each other, such that the patient does not need to balance or compensate any tilts between the lower positioning surface <NUM> and the tread surfaces <NUM>. However, the lower positioning surface <NUM> and the tread surfaces <NUM> may also have a non-zero angle relative to each other. In this case, the tread surfaces <NUM> are preferably oriented such that they extend perpendicular to the vertical gravitational force, such that the patient does not need to balance.

In the embodiment of <FIG>, the treads <NUM> of the staircase <NUM> are cuboids and shaped such that in the retracted state <NUM>, all extendable treads <NUM> may be moved into a volume defined by the lowermost tread <NUM>.

<FIG> show two further embodiments of the staircase <NUM> according to the invention.

As illustrated in <FIG>, the individual treads <NUM> may also be formed as a series of neighboring cuboids that have essentially the same geometry, wherein in the retracted state <NUM>, their tread surfaces <NUM> extend in a common extension plane <NUM>. In the extended state <NUM>, the cuboids forming the treads <NUM> and in particular their tread surfaces <NUM> are moved vertically upwards such that the staircase <NUM> can be used as intended.

As shown in the embodiment of <FIG>, the staircase <NUM>, particularly when in the extended state <NUM>, may also be symmetric, such that the patient may climb up the staircase <NUM> on one side and down the staircase <NUM> on another side. The staircase <NUM> may also form a tread pyramid, wherein the tread surfaces <NUM> of higher treads <NUM> become gradually smaller.

<FIG> show an exemplary embodiment of the staircase <NUM> according to the invention with just two treads <NUM> and guidance units <NUM> arranged on the staircase <NUM>, particularly on the treads <NUM> of the staircase. The guidance units <NUM> are preferably configured to be slidable between at least a first and a second position <NUM>,<NUM> so as to move the respective extendable tread <NUM> between the retracted and the extended state <NUM>,<NUM>. Moreover, the guidance units <NUM> may be configured to receive locking elements configured to reversibly lock and unlock the guidance unit <NUM> in the first and second position <NUM>,<NUM>.

<FIG> shows a top view (i.e. a view of the x-y-plane) of the exemplary embodiment with just two treads <NUM>. The at least one respective guidance unit <NUM> may be arranged for example on two neighboring vertical walls of neighboring treads <NUM>, slidably connecting the neighboring treads <NUM>. The at least one guidance unit <NUM> may for example be mounted on an outside or an inside of the respective vertical wall.

As demonstrated also in the side view (here a view of the z-x-plane) of the present embodiment shown in <FIG>, the at least one guidance <NUM> unit may be arranged vertically (i.e. along the z-direction). In this representation, the first position <NUM> of the guidance unit <NUM> may be understood as a position along the vertical z-axis. If the guidance unit <NUM> is in its first position <NUM>, as shown in <FIG>, the respective extendable tread <NUM> may be in the retracted state <NUM> with the tread surfaces <NUM> of the respective tread <NUM> and the neighboring tread <NUM> extending within a common extension plane <NUM>. To ensure stability and a safe transfer between the retracted and the extended state <NUM>,<NUM>, the staircase <NUM> may comprise a plurality of guidance units <NUM> arranged at multiple sites of two neighboring treads <NUM>.

Now referring to <FIG>, if the guidance unit is moved into the second position <NUM>, the respective extendable tread <NUM> may be in the extended state <NUM> such that the respective tread <NUM> may be in a position outside a volume defined by the (lower) neighboring tread <NUM> wherein the respective tread surface <NUM> is arranged above the tread surface <NUM> of the (lower) neighboring tread <NUM>.

In order to lock a tread <NUM> in the retracted or the extended state <NUM>,<NUM>, the staircase <NUM> may additionally comprise locking elements. As shown in <FIG>, the locking elements may for example comprise a pivoting magnet <NUM> with a locking pin <NUM>. The pivoting magnet <NUM> may be configured to rotate around a respective axis C, particularly a horizontal axis within the x-y-plane, particularly parallel to the y axis, as an extendable tread <NUM> is moved between the retracted and the extended state <NUM>,<NUM>. The rotation may cause the locking pin <NUM> to engage with the guidance unit <NUM> at least if the guidance unit <NUM> is in the first or second position <NUM>,<NUM>, so as to fix the tread <NUM> in the retracted or extended state <NUM>,<NUM>. The mechanism shown in <FIG> may likewise be applied as locking element for all other embodiments of the present invention if applicable.

<FIG> shows a side view of another embodiment of the present invention, wherein at least one guidance unit <NUM> may further be pivotable around an axis A within the x-y-plane, particularly parallel to the y-axis. Again, the present embodiment describes just two treads <NUM> as an example, even though the number of treads <NUM> may be arbitrary as stated above. In this embodiment, the guidance unit <NUM> may for example be arranged essentially horizontally in the retracted state <NUM>. In order to transfer the respective extendable tread <NUM> from the retracted state <NUM> to the extended state <NUM>, the guidance unit <NUM> may be pivoted around the axis A, such that the respective tread surface <NUM> of the respective extendable tread <NUM> is arranged vertically above the tread surface of the neighboring tread <NUM>.

To lock the extendable tread <NUM> in the extended state <NUM>, upon the rotation of the guidance unit <NUM> around the axis A, a locking element connected to the guidance unit <NUM> may slide from the first position <NUM> to the second position <NUM> along the guidance unit <NUM> so as to fix the extendable tread <NUM> in the retracted state <NUM> or the extended state <NUM>. To this end, the locking element may for example comprise a locking pin <NUM> that engages via through holes <NUM> of a guidance unit <NUM> with a vertical wall of the respective tread <NUM>. The locking pin <NUM> may be inserted for manually, or, for example, by a lifting magnet <NUM>.

<FIG> shows a schematic cross-section of the lifting magnet <NUM> slidably arranged on the guidance unit <NUM>, wherein the guidance unit <NUM> comprises at least two through holes <NUM> that may be used to engage the locking pin <NUM> via the respective through hole <NUM> so as to fix the guidance unit <NUM> in the first or second position <NUM>,<NUM>. The first or second position <NUM>,<NUM> may correspond to the retracted and the extended state <NUM>,<NUM> of the respective extendable tread <NUM>. The mechanism shown in <FIG> may likewise be applied to pivotable guidance units <NUM> and be used as a locking element for all other embodiments of the present invention if applicable.

<FIG> show side views of further embodiments of a staircase <NUM> of the present invention with just two treads <NUM> as an example, even though the number of treads <NUM> may be arbitrary as stated above.

As shown in <FIG>, the staircase <NUM> may comprise support struts <NUM> that may be used to support and lock a tread <NUM> in the extended state <NUM>. Preferably, the support struts <NUM> may be pivotable support struts <NUM> around at least one respective axis B parallel to the horizontal x-y plane, particularly parallel to the y-axis, so as to facilitate a transition of a respective tread <NUM> between the retracted state <NUM> and the extended state <NUM>. The pivotable support struts <NUM> may for example be mounted on at least one vertical wall of the respective tread <NUM>. The pivotable support struts <NUM> may particularly be mounted on the outside and/or the inside of the respective vertical wall. Additionally, the staircase <NUM> may comprise support blocks <NUM> that may be used to support the pivotable support struts <NUM> in the extended state <NUM>. To this end, a pivotable support strut <NUM> of the respective extendable tread <NUM> may be oriented essentially vertically above a corresponding support block <NUM> of the (lower) neighboring tread, as shown in <FIG>. The support blocks <NUM> may for example be mounted on at least one vertical wall of the respective tread <NUM>.

<FIG> shows another embodiment of the present invention, wherein the pivotable support struts <NUM> connect neighboring treads <NUM> such that the support struts <NUM> are pivotable around a first pivot axis B1 comprised by a first tread <NUM> and around a second pivot axis B2 comprised by a second tread <NUM> being a neighboring tread <NUM> of the first tread <NUM>. Preferably, the first and the second pivot axis B1,B2 are parallel to each other and parallel to the horizontal x-y-plane, particularly parallel to the y-axis. In this embodiment, the second tread <NUM> may be pivoted above the first tread <NUM> and safely positioned beyond a dead center <NUM> defined by the axis B1 such that the second tread <NUM> is supported by the tread surface <NUM> of the first tread <NUM> in the extended state <NUM>.

<FIG> shows yet another embodiment of the present invention, wherein the pivotable support struts <NUM> are formed by at least one of the vertical walls of the respective extendable tread <NUM>. In this embodiment, the vertical wall may be oriented essentially vertically in the extended state <NUM> while in the retracted state <NUM>, it may be oriented essentially horizontally or at an arbitrary angle relative to the horizontal x-y-plane, as shown in <FIG>. Similar to the embodiment shown in <FIG>, the at least one vertical wall forming the pivotable support strut <NUM> may for example be supported by one or more corresponding support block <NUM>.

<FIG> show side views of further embodiments of a staircase <NUM> of the present invention with just three treads <NUM> as an example, even though the number of treads <NUM> may be arbitrary as stated above.

In the embodiment shown in <FIG>, the respective pivotable support struts <NUM> of a respective extendable tread <NUM> may pivot around a respective pivot axis C1,C2. In this embodiment, the pivotable support struts <NUM> may be arranged vertically and supported by the lower positioning surface <NUM> in the extended state <NUM>. In this particular embodiment, in the extended state <NUM>, the pivotable support struts <NUM> of every tread <NUM> preferably extend from its respective pivot axis C1,C2 down to the lower positioning surface <NUM>, so as to support the extended treads <NUM> directly on the lower positioning surface <NUM>. While a vertical orientation of the pivotable support struts <NUM> in this embodiment may be advantageous in the extended state <NUM> so as to minimize or avoid a tilt caused by a patient or user stepping on the tread surface <NUM> of an extended tread, the orientation of the pivotable support struts <NUM> in the retracted state <NUM> may deviate from a horizontal orientation depending on the constructive details of the staircase <NUM>, as shown in <FIG>.

<FIG> shows another embodiment of the present invention, wherein the pivotable support struts <NUM> may connect neighboring treads <NUM> such that the pivotable support struts <NUM> are pivotable around the first and second pivot axis B1,B2 as well as a third pivot axis B3 parallel to the first and second pivot axis B1, B2, forming double levers <NUM> configured to reversibly pivot the respective extendable tread <NUM> between the extended and retracted state <NUM>,<NUM>.

<FIG> present various embodiments of the present invention, showing various extension elements configured to extend or retract the treads <NUM> into the extended and the retracted state <NUM>,<NUM>.

Particularly, <FIG> refers to an embodiment of the present invention wherein the staircase <NUM> comprises recesses <NUM>. The recesses <NUM> may be used for manual extension and retraction of individual or all treads <NUM> by a user. For instance, individual or all extendable treads <NUM> may be extended by pulling the treads <NUM> vertically up along the z-axis perpendicular to the x-y-plane. The treads <NUM> may be supported or locked for example using the pivotable support struts <NUM> and optionally in combination with the support blocks <NUM> and/or the guidance units <NUM>, as explained in the embodiments above. As shown in <FIG>, the recesses <NUM> may for example be arranged on the respective tread surfaces <NUM> of every extendable tread <NUM>. After modularly locking or unlocking individual treads by the locking elements, individual extendable treads <NUM> may be manually extended or retracted via the recesses <NUM>. After locking or unlocking all treads <NUM> by the locking elements, all extendable treads <NUM> may be manually extended or retracted via the recesses <NUM>.

<FIG> refers to an embodiment of the present invention wherein the staircase <NUM> comprises a chain <NUM>. The chain <NUM> may be arranged essentially horizontally in the retracted state. After modularly locking or unlocking individual extendable treads <NUM> by the locking elements, individual treads <NUM> may be extended or retracted via the chain <NUM>. After locking or unlocking all treads <NUM> by the locking elements, all treads <NUM> may be extended or retracted via the chain <NUM>. The chain <NUM> may be operated manually, or by an optional chain actuator.

<FIG> refers to an embodiment of the present invention wherein the staircase <NUM> comprises a linear actuator <NUM>. The linear actuator <NUM> may be connected to members connecting individual treads <NUM>. As shown in <FIG>, the linear actuator <NUM> may be arranged horizontally and configured to extend or retract the treads <NUM> by moving along the horizontal direction. After modularly locking or unlocking individual extendable treads <NUM> by the locking elements, individual extendable treads <NUM> may be extended or retracted via the linear actuator <NUM>. After locking or unlocking all extendable treads <NUM> by the locking elements, all extendable treads <NUM> may be extended or retracted via the linear actuator <NUM>.

<FIG> refers to an embodiment of the present invention wherein the staircase <NUM> comprises a linear actuator <NUM> that is further pivotable around an axis D wherein it is connected to the lowermost and upmost tread <NUM>,<NUM> of the staircase <NUM>. After modularly locking or unlocking individual treads by the locking elements, individual treads may be extended or retracted via the pivotable linear actuator <NUM>. After locking or unlocking all treads <NUM> by the locking elements, all treads <NUM> may be extended or retracted via the pivotable linear actuator <NUM>.

<FIG> refers to an embodiment of the present invention wherein the staircase <NUM> comprises a scissor lift <NUM>. The scissor lift <NUM> may comprise pivotable X-shaped members connecting the individual treads <NUM>. As shown here, the scissor lift may also only connect for example every second tread <NUM>. The scissor lift <NUM> may optionally be controlled by a scissor lift actuator. After modularly locking or unlocking individual extendable treads <NUM> by the locking elements, individual extendable treads <NUM> may be extended or retracted via the scissor lift <NUM>. After locking or unlocking all extendable treads <NUM> by the locking elements, all extendable treads <NUM> may be extended or retracted via the scissor lift <NUM>.

Additionally, the staircase <NUM> may comprise a control unit (not shown) configured to control the locking elements, and/or the extension elements shown in <FIG>. The control unit may permit automated control over the staircase <NUM> and particularly the extension, retraction, locking and unlocking of the treads <NUM>, such that the staircase <NUM> can be set up automatically, for example by the patient or medical personal.

<FIG> shows another embodiment of the present invention wherein the staircase <NUM> comprises a cover lid <NUM>. The cover lid <NUM> may be arranged above the common extension plane <NUM> to cover and close the staircase <NUM> if all treads <NUM> are in the retracted state <NUM>. Using the cover lid <NUM>, the staircase <NUM> may be closed and safely stored when not in use. When in use, and particularly when in use in the extended state <NUM>, the staircase <NUM> may comprise a ramp <NUM> configured to be mounted to the upmost tread <NUM>. As such, the ramp <NUM> may connect the lower positioning surface <NUM> and the tread surface <NUM> of the upmost tread <NUM>. The ramp <NUM> may be used by a patient to practice walking on an oblique plane in addition to climbing stairs. A pitch angle of the oblique plane may be tuned by varying the number of extended treads <NUM>. In another advantageous embodiment of the present invention, the ramp <NUM> may comprise the cover lid <NUM>.

<FIG> shows another embodiment of the present invention wherein the staircase <NUM> comprises rolls <NUM>. The rolls <NUM> may be mounted for example on the front or backside of the staircase <NUM>, i.e. in the area of the two ends along the length of the staircase <NUM> extending along the y-axis and be used to pull or roll the staircase <NUM> over the lower positioning surface <NUM>, so as to facilitate the transport of the staircase <NUM>, particularly in the retracted state <NUM>.

<FIG> show embodiments of the present invention wherein the staircase <NUM> comprises at least one spring <NUM>. The at least one spring <NUM> may be used to reduce the tilting moment acting on the treads <NUM>, particularly a tilting moment acting when the respective tread <NUM> is moved between the retracted and the extended state <NUM>,<NUM>, i.e. when the respective tread <NUM> is not locked in the retracted or the extended state <NUM>,<NUM>. Preferably, as shown in <FIG>, the at least one spring <NUM> may be arranged in an at least one edge section of the tread surface <NUM> so as to reduce the tilting moment. The at least one spring <NUM> may extend essentially between next neighboring treads <NUM>, so as to reduce the tilting moment between next neighboring treads <NUM> by supporting the respective spring <NUM> on the next lower tread surface <NUM> respectively for every extendable tread <NUM> in a cascade-manner down to the lower positioning surface <NUM>, as shown in <FIG>.

As shown in <FIG>, the at least one spring <NUM> may also be pivotable around a respective axis and connect next neighboring treads <NUM>, so as to reduce the tilting moment.

Claim 1:
A modularly extendable staircase (<NUM>) comprising a plurality of extendable treads (<NUM>), each tread (<NUM>) comprising a tread surface (<NUM>), wherein each tread (<NUM>) is configured to be moved from a retracted state (<NUM>) to an extended state (<NUM>) such that when each tread (<NUM>) is arranged in its retracted state (<NUM>), the tread surfaces (<NUM>) extend in a common extension plane (<NUM>), and wherein when the respective tread (<NUM>) is arranged in an extended state (<NUM>) the tread surface (<NUM>) of the respective tread (<NUM>) extends parallel to and above a tread surface (<NUM>) of a neighboring tread (<NUM>), characterized in that the staircase (<NUM>) comprises at least one guidance unit (<NUM>) arranged at the treads (<NUM>) and configured to be slidable between and fixable at at least a first and a second position (<NUM>,<NUM>), wherein the first and second position (<NUM>,<NUM>) correspond to the retracted and the extended state (<NUM>,<NUM>) of a respective extendable tread (<NUM>), respectively, and wherein the at least one guidance unit (<NUM>) is connecting the respective tread (<NUM>) with its neighboring treads (<NUM>,<NUM>).