Patent Description:
<CIT> discloses a cam portion composed of first to fifth arcuate surfaces. The first arcuate surface is arranged such that when a cover member of a cellular telephone is located in a neutral position, a plate spring portion contacts a crossing portion where the first arcuate surface crosses an orthogonal line passing through a center of curvature of the first arcuate surface and orthogonal to a rotation axis. A second and a third arcuate surface are arranged on both sides of the first arcuate surface. Radii of curvature of the second and third arcuate surfaces are set to be smaller than a radius of curvature of the first arcuate surface.

<CIT> discloses a curved spring configured to generate, based on a relative approaching displacement of a one-side bearing section and an other-side bearing section in an approach/separation direction, an urging force in a separation direction in which the one-side bearing section and the other-side bearing section are separated from each other. A linear elastic body is provided to extend on a closed curve, which includes a one-side portion arranged along a circumferential direction of the one-side bearing section and an other-side portion arranged along a circumferential direction of the other-side bearing section, and to constitute elastic sections of two lines between the one-side portion and the other-side portion.

<CIT> discloses a hinge that includes a shaft, a hinge leaf engaged with the shaft, a band clamped around the shaft for rotation about the shaft and pivotal movement relative to the hinge leaf, and a clutch disposed between the band and the shaft. The clutch includes a collar disposed between the shaft and the band. The clutch is configured to lock and unlock the collar to the shaft. Rotation of the band about the shaft in a first direction locks the collar to the shaft for frictional movement of the band about the shaft at a first resistance level. Rotation of the band about the shaft in a second direction unlocks the collar from the shaft for frictional movement of the band about the shaft at a second resistance level lower than the first resistance level.

<CIT> discloses a support stand leg pivotally supported by a leaf spring relative to a back cover of a computer device or a computer device case. The support stand leg is pivotal between a retracted position against the back cover and an extended position. The leaf spring urges the support stand leg towards the retracted position.

The invention relates to a computing device as defined by independent claim <NUM>. The dependent claims define further advantageous embodiments of the invention.

The accompanying drawings illustrate implementations of the concepts conveyed in the present document. Features of the illustrated implementations can be more readily understood by reference to the following description taken in conjunction with the accompanying drawings. Like reference numbers in the various drawings are used wherever feasible to indicate like elements. Further, the left-most numeral of each reference number conveys the FIG. and associated discussion where the reference number is first introduced. Where space permits, elements and their associated reference numbers are both shown on the drawing page for the reader's convenience. Otherwise, only the reference numbers are shown.

The present concepts relate to devices, such as computing devices employing portions that can be moved relative to one another. Multiple nested leaf springs are positioned as a biasing agent to receive and deliver forces between the first portion and second portion. The leaf springs extend from a first end to a second end to define a perimeter. In contrast with traditional configurations, the first and second ends are contained within the perimeter and not secured to either the first portion or the second portion. Instead, interim regions of the leaf springs receive and/or deliver forces between the first and second portions. This configuration provides a high displacement spring mechanism that can fit within constrained spaces in the device and can be customized to provide a desired force profile. These and other aspects are discussed below.

<FIG> shows an example device <NUM> that includes portions <NUM>, that can be rotationally secured by hinge assemblies <NUM>. In this case, the portions include first portion <NUM>(<NUM>) that is manifest as a tablet <NUM>, second portion <NUM>(<NUM>) that is manifest as a keyboard <NUM>, and portion <NUM>(<NUM>) that is manifest as a kickstand <NUM>. Hinge assembly <NUM>(<NUM>) rotatably couples portions <NUM>(<NUM>) and <NUM>(<NUM>) around hinge axis (HA1) and hinge assembly <NUM>(<NUM>) rotatably couples portions <NUM>(<NUM>) and <NUM>(<NUM>) around hinge axis (HA2). A compact tunable leaf spring assembly (CTLSA) <NUM> can receive and impart forces between elements of the device. In this example, compact tunable leaf spring assembly <NUM>(<NUM>) is positioned relative to tablet <NUM> and keyboard <NUM>. Similarly, compact tunable leaf spring assembly <NUM>(<NUM>) is positioned relative to tablet <NUM> and kickstand <NUM>. Note that the compact tunable leaf spring assemblies <NUM> are shown in ghost to indicate that they would normally be occluded by other elements and therefore would not be visible in this view.

Compact tunable leaf spring assemblies <NUM> lend themselves to dimensionally-constrained applications. For instance, tablet <NUM> can have a dimensionally-constrained thickness (T). Compact tunable leaf spring assembly <NUM>(<NUM>) can provide defined force values within this constrained thickness. (Note that thickness is often referred to relative to the z reference direction and the two are parallel when the measured element is positioned horizontally (e.g., in the position of the keyboard <NUM> in <FIG>)).

Note that while specific applications for CTLSAs <NUM> are illustrated for purposes of explanation, CTLSAs can be employed between any two device elements that have relative movement and/or impart forces on one another.

<FIG> and <FIG> collectively show another example device 100A, that is similar to device <NUM> of <FIG>. In this case, the device 100A includes a tablet <NUM> and a kickstand <NUM> that are rotationally secured by hinge assembly <NUM>. CTLSA <NUM> is configured to impart forces between two elements of the device. In this case, the two elements are the tablet <NUM> and the kickstand <NUM>. The CTLSA <NUM> can be positioned against the tablet <NUM> and can be engaged by a force transfer element <NUM>. In this example, the force transfer element <NUM> is manifest as a tension bar <NUM> that is linked to the kickstand side of hinge assembly <NUM>. The tension bar <NUM> defines a contact structure <NUM> that can be forced against the CTLSA <NUM> by rotation of the kickstand <NUM> and in turn can receive forces from the CTLSA <NUM> to transfer to the kickstand <NUM>. It is contemplated that the CTLSA can be used in other scenarios besides those illustrated and discussed here where a compact force or biasing agent is desired.

The CTLSA <NUM> can include multiple nested leaf springs <NUM>. As can be seen in <FIG>, the illustrated implementation includes three nested leaf springs <NUM>(<NUM>), <NUM>(<NUM>), and <NUM>(<NUM>). The CTLSA <NUM> can provide a small format package of multiple nested leaf springs <NUM> that can be adjusted (tuned) to a wide range of force/deflection characteristics, including high force and high stroke (deflection in the y reference direction). In contrast, typical helical coil springs require a relatively larger diameter (requiring a correspondingly larger thickness) than the present nested leaf springs (on the order of two or more times higher) in order to provide equivalent force/deflection characteristics. This can be a challenge when thickness and/or other dimensions for the spring is limited. The nested leaf springs can provide high stiffness and high stroke in a very small space. In addition, the stiffness characteristics of the CTLSA can be adjusted by varying various parameters, allowing a wide range of linear and nonlinear response profiles.

<FIG> collectively show an example layout of another CTLSA 112A. The suffix "A" is used to indicate that elements of CTLSA 112A may be the same or different from those of CTLSA <NUM> introduced above relative to <FIG> and/or to other CTLSAs discussed below. In this case, the CTLSA 112A includes and/or interacts with a housing <NUM>. Note that from one perspective, the 'housing' can be any structure the leaf springs <NUM> contact. In other cases, such as the illustrated configuration of <FIG>, the housing can be a dedicated structure. In this example, the housing <NUM> defines a perimeter that generally approximates a portion of a rectangle and includes vertical sides <NUM> connected by a bottom <NUM>. In this case, the perimeter is generally planar. A downward force F1 can be applied to the CTLSA 112A via contact structure <NUM> and the CTLSA 112A can generate an opposing upward reaction force F2. This aspect is described in more detail below relative to FIGS.

Note that in this implementation, the leaf springs <NUM> extend from a first end <NUM> to a second end <NUM> and define two loops <NUM> and <NUM>. The loops collectively define at least part of perimeter <NUM> of the leaf springs. In this case, perimeter <NUM> defined by the leaf springs is contained in the perimeter defined by the housing (e.g., within the bounds of the housing). The shape of the loops <NUM> and <NUM> can affect a force profile of the CTLSA <NUM>. In this implementation, the loops <NUM> and <NUM> generally approximate a portion of a rectangle (e.g., are rectangular in shape). Other implementations can have different shapes. For instance, <FIG> shows an implementation where the loops approximate a portion of an oval.

Note, the ends <NUM> and <NUM> can be contained within the perimeter <NUM> and are not directly secured to either of the first or second portions, which in this case are manifest as the contact structure <NUM> and the housing <NUM>. Instead, the ends <NUM> and <NUM> are unbound and are free to move when stress forces are imparted between the contact structure and the housing. Further, the shape of the leaf springs and the housing <NUM> can cause contact between extensive intervening portions <NUM> (labeled on <FIG>) (e.g., between the ends <NUM> and <NUM>) to contact the housing. This can be contrasted with traditional leaf spring configurations where the ends are secured to a first portion and the midpoint of the leaf spring is secured to a second portion that can move relative to the first portion.

<FIG> collectively show an example layout of another CTLSA 112B. The suffix "B" is used to indicate that elements of CTLSA 112B may be the same or different from those of CTLSAs described above and/or below. In this case, CTLSA 112B includes three leaf springs <NUM>. Further, the contact structure <NUM> includes a stroke or displacement limiter <NUM>.

<FIG> shows the contact structure <NUM> just beginning to contact the CTLSA 112B as the contact structure moves along a stroke S. In this case, a dimension W (e.g., width or diameter) of the contact structure <NUM> is greater than a distance or gap G between the loops <NUM> and <NUM>. The movement of the contact structure <NUM> can be due to downward force F1 and impart forces on regions <NUM> of the leaf springs <NUM>. (Note that to avoid clutter on the drawing page, the regions described relative to <FIG> are only specifically designated on the left side of the CTLSA 112B but are applicable on the right side as well). This force F1 causes individual leaf springs <NUM> within a loop <NUM> or <NUM> to interact with one another at region <NUM>, which can produce a reaction force F2. This interaction can cause deformation of the individual leaf springs <NUM> at region <NUM> to provide a relatively small reaction force F2 when accommodating the compression from the contact structure <NUM>. As will be explained in the sequence below, as different regions of the leaf springs <NUM> experience self-contact, contact with the housing <NUM>, and/or contact with other leaf springs, the reaction force can increase.

Note also that in this implementation the leaf springs <NUM> are bilaterally symmetrical when viewed along the stroke S of the contact structure. Thus, effects of the contact structure <NUM> on the left and right sides of the leaf springs (e.g. loops <NUM> and <NUM>) tends to be equivalent. Other implementations may be different on the left and right sides.

<FIG> shows the contact structure <NUM> continuing to move downward and exert forces on CTLSA 112B. At this point, ends <NUM>(<NUM>) and <NUM>(<NUM>) of outermost leaf spring <NUM>(<NUM>) begin to contact an intermediate or interim portion <NUM> of leaf spring <NUM>(<NUM>). This self-contact increases the resistance of the leaf springs <NUM> to further downward movement of the contact structure <NUM>. Accordingly, the reaction force F2 can increase relative to the reaction force F2 of <FIG>.

<FIG> shows the contact structure <NUM> continuing to move downward along its stroke and exert forces on CTLSA 112B. At this point, the self-contact explained above relative to <FIG> limits further downward deflection of region <NUM>. As a result, the downward movement of the contact structure <NUM> pushes upper regions <NUM> outward laterally away from each other and toward sides <NUM>. Accordingly, the reaction force F2 can increase relative to the reaction force F2 of <FIG>.

<FIG> shows the contact structure <NUM> continuing to move downward and exert forces on CTLSA 112B. At this point, the regions <NUM> are engaging sides <NUM>, which limit further opening of the spring (e.g. the left side of the leaf spring region <NUM> is blocked from moving farther away from the right side of the leaf spring). As a result, further displacement causes internal compression of the left side (e.g., region <NUM>) between the contact structure <NUM> and the side <NUM>(<NUM>) (and similar compression is caused on the right side of the CTLSA 112B). Accordingly, the reaction force F2 can increase relative to the reaction force F2 of <FIG>. Thus, from one perspective the reaction force F2 can increase as vertical displacement of the contact structure increases because more regions of the leaf springs become involved in the displacement.

<FIG> also shows the limiter <NUM> starting to contact leaf spring <NUM>(<NUM>) at its interim portion <NUM>. The interim portion is elevated slightly above the bottom <NUM> of housing <NUM>. Displacing the interim portion against the bottom will contribute to the reaction force F2. Once contact has occurred further displacement is blocked. Thus, the stroke of the displacement of the contact structure <NUM> can be measured as the vertical position change of the contact structure <NUM> between <FIG> and <FIG>. (As mentioned above, there is a slight amount of additional displacement before <FIG> and after <FIG>).

As explained above, as different regions of the leaf springs <NUM> experience self-contact, contact with the housing, and/or contact with other leaf springs, the reaction force can change. These can be considered examples of parameters that can be adjusted to shape the desired reaction force profile of the CTLSA 112B. Further parameters can include: spring thickness (in the z reference direction); spring width (in the x reference direction); housing width (in the x reference direction); housing height (in the y reference direction); contact structure dimensions (e.g., diameter); number of leaf springs; clearance between housing and outer leaf spring of the spring nest; spacing of internal springs of spring nest; clearance between outer spring ends and top and bottom of the housing; outer spring end bend angle; and/or spring corner bend radius, among others. Several of these parameters are discussed above relative to <FIG>. Several parameters are described in the discussion below relative to <FIG>.

<FIG> collectively show another example CTLSA 112C that includes an adjustable housing <NUM>. In this case, the housing <NUM> includes a fixed bottom <NUM> secured to fixed sidewalls <NUM>. The fixed sidewalls <NUM> are adjustably secured to sides <NUM> via adjustment mechanisms <NUM>. The function of the adjustment mechanism <NUM> can be understood by comparing distance D1 between sides <NUM> in <FIG> to distance D2 between the sides <NUM> in <FIG>. In <FIG> distance D1 is greater and the left and right sides of the leaf springs <NUM> have more room to move away from each other before contacting sides <NUM>. In contrast, in <FIG>, the sides have been adjusted toward each other to decrease the distance between the sides <NUM>. As such, the sides of the leaf springs will contact the sides <NUM> sooner (e.g., when less vertical stroke of the contact structure <NUM> has occurred compared to <FIG>). Thus, the reaction force profile of the CTLSA 112C in <FIG> will be different than the reaction force profile of the CTLSA 112C in the configuration of <FIG>.

<FIG> shows another example CTLSA 112D that includes five leaf springs <NUM>(<NUM>)-<NUM>(<NUM>) nested within housing <NUM> and that define a perimeter <NUM>. In this example, the perimeter is planar (e.g., lies in xy reference plane). In this case, all of the leaf springs terminate with a vertical run beneath the contact structure <NUM>. Increasing the number of leaf springs <NUM> can change the reaction force profile of the CTLSA 112D, such as by making the reaction force greater.

<FIG> shows another example CTLSA 112E that is similar to CTLSA 112D of <FIG>. However, in this case, leaf spring <NUM>(<NUM>) terminates with a horizontal run outside the bounds of the contact structure. In this configuration, leaf spring <NUM>(<NUM>) does not contribute to the reactive force until later in the vertical stroke of the contact structure <NUM> when compared to the implementation of <FIG>. Thus, the terminus of the leaf springs can be a parameter that can alter the reaction force profile of the CTLSA 112E.

<FIG> shows another example CTLSA 112F. When compared to <FIG>, the bends of the leaf spring <NUM> in <FIG> tend to be more gradual and continuous so that the leaf springs approximate portions of two side-by-side ovals. In contrast, in the implementations of <FIG>, the bends tend to be sharper and tend to be separate by generally straight sections so that the leaf springs approximate portions of two side-by-side rectangles or squares. Thus, the shape of the leaf springs can be a parameter that can alter the reaction force profile of the CTLSA 112F.

<FIG> collectively show another example CTLSA <NUM>. In this case, the CTLSA includes housing <NUM> and three nested leaf springs <NUM>(<NUM>)-<NUM>(<NUM>). In this implementation, as shown in the sequence represented by <FIG>, initially as the contact structure <NUM> begins to move downward, the CTLSA <NUM> can function in a similar manner to other example CTLSAs described above. Note however, that in this case, the leaf springs <NUM> are shaped to define opposing indents <NUM>. The indents <NUM> can collectively define an inner perimeter (e.g., circumference) that approximates an outer perimeter (e.g., circumference) of the contact structure.

<FIG> shows the downward movement of the contact structure <NUM> along its stroke has aligned the contact structure with the indents <NUM> and leaf springs <NUM> have rebounded around the contact structure. At this point, the leaf springs <NUM> and their associated indents <NUM> can function as a detent <NUM> to retain the contact structure <NUM>.

Thus, in the sequence shown in <FIG>, the reaction force profile of CTLSA <NUM> can be similar to the reaction force profiles of implementations described above. However, when the contact structure <NUM> is engaged by the detent <NUM> in <FIG>, the reaction force profile diverges from those above in that rather than 'pushing back' against the downward movement of the contact structure, the detent now applies a retention force, such that additional force is required to move the contact structure upward or downward out of the detent. Once out of the detent, the reaction force profile can one again be similar to other reaction force profiles described above.

<FIG> shows another example CTLSA <NUM>. In this case, housing <NUM> is sealed and defines baffles <NUM> and openings <NUM>. The housing <NUM> can be partially filled with liquid <NUM> to provide a dampening effect on vertical movement of the contact structure <NUM>.

From one perspective, as downward force from the contact structure <NUM> causes deformation of the leaf springs <NUM>, they displace fluid and induce non-recoverable fluid shear forces. Such a CTLSA can be used to reduce mechanical vibration and can function as a spring and damper simultaneously. If damping only is required with minimal stiffness, a small spring thickness can be specified.

<FIG> shows a graph <NUM> of example reaction force profiles (e.g., force/displacement profiles) <NUM> that can be generated by example CTLSAs. The reaction force profiles <NUM> represent deflection in millimeters on the horizontal axis and Force in Newtons on the vertical axis.

Reaction force profile <NUM>(<NUM>) relates to a CTLSA implementation that employs three leaf springs having overall dimensions of <NUM> millimeters (mm) wide (in the x reference direction) by <NUM> high (in the y reference direction). Individual leaf springs are <NUM> (in the z reference direction) by <NUM> (in the x or y reference directions).

Reaction force profile <NUM>(<NUM>) relates a CTLSA implementation that employs three leaf springs having overall dimensions of <NUM> millimeters (mm) wide (in the x reference direction) by <NUM> high (in the y reference direction). Individual leaf springs are <NUM> (in the z reference direction) by <NUM> (in the x or y reference directions) (e.g., <NUM> thinner than the leaf springs of reaction force profile <NUM>(<NUM>). Reaction force profile <NUM>(<NUM>) relates to a CTLSA implementation that employs two leaf springs instead of three, but otherwise has the same dimensions as the CTLSA of reaction force profile <NUM>(<NUM>).

As mentioned above, the reaction force F2 can relate to the degree of leaf spring engagement, which can relate to multiple parameters including the overall size, number of leaf springs, and/or dimensions of leaf springs detailed in the directly preceding paragraph.

This aspect can be understood by reviewing example reaction force profile <NUM>(<NUM>) in combination with <FIG>. <FIG> shows the reaction force is generated by region <NUM> and tends to have a first range <NUM> associated with this engagement. This continues to be the case until spring ends <NUM> and <NUM> contact interim portion <NUM> in <FIG>. This contact adds to the reaction force in a second range <NUM>. Next the vertical compression and horizontal displacement of <FIG> is added to the deformation force in a third range <NUM>. This continues until the leaf springs contact sides <NUM> in <FIG> and the deformation of each side of the hinge springs is added to the reaction force in a fourth range <NUM>. At this point, which in some implementations is reached at about <NUM>-<NUM> of stroke, the reaction force can stay relatively constant for the rest of the stroke of the contact structure.

Reaction force profile <NUM>(<NUM>) shows the effect of reducing the leaf spring thickness parameter from <NUM> to <NUM>. Reaction force profile <NUM>(<NUM>) shows the effect of changing the parameter relating to the number of leaf spring from three to two, which reduces the force by about <NUM>%, and the reaction force profile is smoother. Of course, these are example reaction force profiles provided for purposes of explanation, but they highlight the predictable nature of the CTLSA and its customizability based on adjusting one or more parameters to achieve a desired reaction force profile.

In view of the description above, the CTLSA concepts can allow customization of the CTLSA components to achieve a broad range of spring stiffness (spring force), and a broad range of force/deflection profiles. There can be multiple leaf springs that deform and interact with one-another and/or with the housing. By changing the CTLSA dimensions and/or number of leaf springs, a wide range of spring force/deflection profiles can be achieved.

The leaf springs can be formed from any suitable material. For instance, spring steel could be employed, though other materials, such as stainless steel, other metals, polymers, and composites are contemplated. Within a CTLSA the leaf springs could all be constructed from the same material. Alternatively, some leaf springs could be made from one material while other leaf springs are made from another material.

The present CTLSA concepts can be utilized with any type of device, such as but not limited to, notebook computers, smart phones, wearable smart devices, tablets, and/or other types of existing, developing, and/or yet to be developed devices.

Although techniques, methods, devices, systems, etc., pertaining to compact leaf spring assemblies are described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described. Rather, the specific features and acts are disclosed as example forms of implementing the claimed devices.

Various examples are described above. Additional examples are described below. One example includes a device comprising a tablet that is rotatable relative to a kickstand and a compact tunable leaf spring assembly positioned to receive forces associated with relative rotation between the tablet and the kickstand, the compact tunable leaf spring assembly including multiple nested leaf springs, individual leaf springs extending from a first end to a second end and defining a planar perimeter where the first end and the second end are contained within the perimeter and are not secured to either the tablet or the kickstand.

Another example can include any of the above and/or below examples where the compact tunable leaf spring assembly further comprises a housing and wherein a shape of the housing generally approximates the planar perimeter of the individual leaf springs.

Another example can include any of the above and/or below examples where the housing is positioned in the tablet.

Another example can include any of the above and/or below examples where the device further comprises a contact structure that is coupled to the kickstand.

Another example can include any of the above and/or below examples where rotation of the kickstand causes the contact structure to engage the leaf springs without contacting the ends of the leaf springs or a midpoint of the leaf springs.

Another example can include any of the above and/or below examples where the leaf springs are bilaterally symmetrical into left and right sides along a stroke of the contact structure.

Another example can include any of the above and/or below examples where movement of the contact structure along the stroke causes the left and right sides of the contact structure to move away from one another.

Another example can include any of the above and/or below examples where the left and right sides of the contact structure move away from one another until contacting the housing.

Another example includes a device comprising a first portion that is moveable relative to a second portion and multiple nested leaf springs positioned to receive forces between the first portion and the second portion, individual leaf springs extending from a first end associated with a first loop to a second end associated with a second loop and the first and second ends are not secured to either the first portion or the second portion to receive the forces.

Another example can include any of the above and/or below examples where the loops are symmetric.

Another example can include any of the above and/or below examples where the loops approximate a portion of a rectangle.

Another example can include any of the above and/or below examples where the loops approximate a portion of an oval.

Another example can include any of the above and/or below examples where all of the multiple nested leaf springs are the same shape.

Another example can include any of the above and/or below examples where an outermost individual leaf spring of the multiple nested leaf springs is a different shape than at least one other individual leaf spring.

Another example can include any of the above and/or below examples where the multiple nested leaf springs are positioned in the first portion and further comprise a contact structure linked to the second portion, the contact structure configured to move along a stroke between the first loop and the second loop.

Another example can include any of the above and/or below examples where the contact structure has an outside dimension that is greater than a gap between the first loop and the second loop.

Another example can include any of the above and/or below examples where movement of the contact structure along the stroke forces the first and second loops away from one another.

Another example can include any of the above and/or below examples where the multiple nested leaf springs are positioned within a housing contained in the first portion.

Another example can include any of the above and/or below examples where the movement of the contact structure along the stroke forces the first and second loops away from one another until the first and second loops contact the housing and then further movement of the contact structure along the stroke deforms the first and second loops.

Another example includes a device comprising a first portion that is moveable relative to a second portion and a leaf spring positioned to receive forces between the first portion and the second portion, the leaf spring extending from a first end to a second end and defining a perimeter where the first end and the second end are contained within the perimeter and not secured to either the first portion or the second portion.

Claim 1:
A computing device (<NUM>), comprising:
a first portion (<NUM>(<NUM>)) of the computing device (<NUM>) that is moveable relative to a second portion (<NUM>(<NUM>)) of the computing device (<NUM>);
multiple nested leaf springs (<NUM>) positioned to receive forces between the first portion (<NUM>(<NUM>)) and the second portion (<NUM>(<NUM>)), individual leaf springs (<NUM>) extending from a first end (<NUM>) associated with a first loop (<NUM>) to a second end (<NUM>) associated with a second loop (<NUM>), and the first and second ends (<NUM>, <NUM>) not being secured to either the first portion (<NUM>(<NUM>)) or the second portion (<NUM>(<NUM>)) to receive the forces; and
a contact structure (<NUM>) linked to the second portion (<NUM>(<NUM>)), the contact structure (<NUM>) configured to move along a stroke (S) between the first loop (<NUM>) and the second loop (<NUM>) to transfer the forces,
wherein the multiple nested leaf springs (<NUM>) are positioned in the first portion (<NUM>(<NUM>)).