Patent Description:
<CIT> discloses a swing bridge for converting a rotary motion into an oscillating motion. This known swing bridge can be used in an electrically driven device such as a dry shaver. The swing bridge comprises an oscillating body with a coupling, a drive shaft and two swing arms. The coupling comprises a slot for coupling an eccentrically rotatable drive pin coupled to a drive shaft of an electric motor to the swing bridge. Further, the drive shaft of the oscillating body may be coupled to a cutter unit, wherein the two drive shafts, i.e. the drive shaft of the electric motor and the drive shaft of the oscillating body, are arranged in a common plane running through the slot. The swing arms can be coupled to a housing of an electrically driven device. Thus, during use of an electrically driven device, the oscillating body of the swing bridge is only free to move in a linear direction between the two swing arms. The swing bridge, therefore, converts a rotary motion of a drive pin into a linear oscillating motion of the drive shaft. The alignment of the drive shafts in a common plane may have drawbacks regarding the assembly of an electrically driven device, as the drive shaft of the electric motor has to be arranged in line with the drive shaft of the swing bridge. In addition, the swing arms of the swing bridge are complicated to form and need plenty of space in a longitudinal direction. Further, an additional coupling comprising a slot is needed in order to couple the swing bridge to an electric motor.

Prior art document <CIT> discloses the preamble of claim <NUM>.

It is an object of the present disclosure to provide a swing bridge and an electrically driven device comprising the swing bridge for converting a rotary motion into an oscillating motion, especially into a linear oscillating motion of a cutter unit, improving the required space within an electrically driven device as well as the way of assembling the swing bridge to an electric motor and a cutter unit.

This object is solved by a swing bridge for converting a rotary motion into an oscillating motion, especially into a linear oscillating motion as defined in claim <NUM> and by an electrically driven device defined in claim <NUM>.

The swing bridge comprises an oscillating body defining a plane, wherein the oscillating body comprises a slot arranged in the plane, and wherein a first axis extends through the center of the slot perpendicular to the plane. The feature of the "swing bridge" may also be named "oscillation bridge" hereinbelow. Further, the oscillating body comprises a drive shaft protruding perpendicular to the plane along a second axis, and two webs extending at least substantially perpendicular to the plane. The webs or wings have a free end facing away from the oscillating body for securing the oscillating body to permit movement of the oscillating body substantially only parallel to the plane, i.e. in one direction. The first axis that extends through the center of the slot perpendicular to the plane and the second axis are offset at least in one direction of the plane, and the second axis is located in a corner section of the oscillating body.

Preferably, the plane defined by the oscillating body comprises a greater length in its longitudinal direction, i.e. the swing direction, than in its transverse direction. The first axis, which extends through the slot perpendicular to the plane, extends through the center of the slot Preferably, the axes are offset at least in said longitudinal direction. Further, it is preferred, when the second axis is arranged in an edge area of the plane. The axes may also be offset in said transverse direction or, preferably, in a combined longitudinal and transverse direction. Independent of the direction of the offset, the offset between the two axes allows to arrange the drive shaft of an electric motor offset to the drive shaft of the oscillating body and thus an offset power transmission. The slot may be an elongated hole or a groove. Preferably, the elongated hole or groove has its smaller widening in the longitudinal direction of the swing bridge. Preferably, the swing bridge comprises two webs equally arranged on each side in longitudinal direction of the slot. The webs may also refer to the term swing arms, so that the terms swing arm and web may be used synonymously. Preferably, the webs or swing arms are arranged at the lateral ends of the oscillating body in longitudinal direction. Still, there may be embodiments of the invention, wherein it is preferred that the webs are arranged between the slot and the lateral ends in the longitudinal direction of the oscillating body. Further, the webs of the oscillating body each comprise a free end facing away from the oscillating body. Preferably, the width of the webs in the transverse direction is equal to the width of the oscillating body in the transverse direction. However, the width of the webs may also be smaller and/or may also differ or alternate between the oscillating body and their free end. Moreover, the webs comprise preferably a plate-type shape, wherein the free ends of the webs can be used to secure the oscillating body. Therefore, the webs may comprise attachment means at their free ends. Each attachment means may have the form of a protrusion or bead facing away from the oscillating body. Preferably, the width of the webs in the transverse direction is greater than the material strength of the webs in the longitudinal direction. The term "material strength" here and on all following pages refers to all features which impact the stiffness of the web, e.g. "material strength" can replaced by the term "material thickness" or other measure to change the stiffness. Consequently, the webs are flexible and thus easily bendable when the oscillating body is moved in its longitudinal direction and the free ends of the webs are secured. However, the webs are stiff when a force acts on the oscillating body in its transverse direction. In addition, it may be preferred, that the webs comprise a different material strength at the end portion to improve the securing. In some embodiments, it may also be preferred, that the oscillating body comprises two webs between the slot and the ending of the oscillating body in the longitudinal direction on one side. In the case, wherein only one side comprises two webs, the opposite side may be arranged within a guiding. The guiding may comprise elastic means in order to provide a force according to the force a web provides, when the oscillating body is shifted and the webs are bent. It is even possible, that the oscillating body does not comprise a web at all and comprises a guiding on either side, such an embodiment however, is not part of the claimed invention.

In one embodiment, the slot may be located substantially centrally on the oscillating body. If the swing bridge comprises two webs equally arranged on each side in the longitudinal direction of the slot, a centered arrangement of the slot on the oscillating body ensures an even load acting on the webs, when the webs are secured and the swing bridge oscillates within an electrically driven device. Therefore, a centered location of the slot on the oscillating body can be understood as centered between the webs in the longitudinal direction and preferably also centered between the edges of the oscillating body in the transverse direction. The slot may be a cut through the oscillating body, i.e. a through hole, or may be a recess, like a groove.

Further, in one embodiment of the swing bridge, the first axis and the second axis may be offset to each other in two directions of the plane. Preferably, the first axis protrudes perpendicular to the plane and through the center of the slot, wherein the second axis is offset in a longitudinal and a transverse direction of the plane. The second axis is located in a corner section of the oscillating body. When the swing bridge is used within an electrically driven device, the second axis is preferably arranged in the center of the device. Therefore, the offset of the two axes allows to arrange an electric motor offset to the center of the swing bridge and thus, offset to the center of the electrically driven device.

One embodiment of the swing bridge may comprise the oscillating body with at least two components arranged on top of one another, wherein each of the components comprises a plate-type section, and wherein the plate-type sections are for example connected in an integrally bonded manner, preferably by ultrasonic welding, or by a form fit. If ultrasonic welding connects the components, preferably at least one of the components comprises welding dots, wherein the other component may comprise respective holes. Further, it is preferred, when the upper component comprises the drive shaft and the lower component comprises the at least one web. Consequently, it may be preferred when the upper component comprises a stiffer material and the lower component comprises a more flexible material. Nevertheless, as an alternative, it may be preferred when the two components are formed as one. Regardless of the number of components, preferably the components of the oscillating body are injection molded. As mentioned before, the slot may be a cut through or may be recess. Due to the fact that the at least two components are arranged on top of each other, it may be advantageous if the slot only cuts through the lower component, i.e. the component closer to the drive pin. Additionally or as an alternative, it may be advantageous if the slot also forms a cut through and/or a recess within the components arranged on top of the lower component. Furthermore, the shape of the at least two components may differ. Therefore, one component may protrude beyond another component at least in the longitudinal direction on at least one side, preferably in the longitudinal direction. The above-mentioned features also account for an oscillating body with only one component.

In addition, the two webs may be an integral part of one of the at least two components. As mentioned before, it is preferred when the two webs comprise a greater width in the transverse direction than the material strength of the webs in the longitudinal direction.

Preferably, the two webs comprise at least partially the same size in transverse direction as the oscillating body and/or the swing bridge. The production is considerably simplified if the two webs are an integral part of one the at least two components. However, it may also be preferred when the webs of the oscillating body are connected to the oscillating body by common connecting means and methods.

In one embodiment, the two components may comprise a plastic material, wherein the plastic material is preferably a type of polyoxymethylene. For the use of ultrasonic welding, the upper and lower component should comprise the same type of plastic material, but they may differ in material properties, like strength, hardness, etc. Furthermore, a high mechanical strength as well as a good flowability are required if thin plastic walls such as webs are formed by injection molding. To achieve a high dimensional accuracy it is further advantageous when the material used for injection molding comprises a relatively low shrinkage rate. Thus, according to one example, the upper component is formed by POM HOSTAFORM C9021 GV3/<NUM> and the lower component is formed by POM ULTRAFORM H2320 <NUM>. Other materials, especially materials comprising the required characteristics, may be used as an alternative.

In an additional or an alternative embodiment, one of the at least two components and the drive shaft may be form-fitted, wherein the drive shaft is preferably overmolded. It may also be preferred if the drive shaft is screwed or connected to at least one of the two components by other common connecting means. Regardless of the type of connection, it may be preferred, if the connection of the drive shaft comprises ribs, wherein the ribs are supported on the oscillating body. Overmolding of the drive shaft offers the advantage of an inexpensive and a comparatively simple production of the swing bridge. In addition, overmolding allows to connect two materials, i.e. the material of the at least one component and the material of the drive shaft, which may otherwise be difficult to join.

In one embodiment, the drive shaft may comprise a metal material. The use of a metallic material has the advantage that the drive shaft wears out less quickly and thus has a higher durability. Since a damage of the drive shaft also causes the function of the swing bridge to fail, a long durability of the drive shaft is desired. This is especially the case, if the drive shaft is non-detachable connected to the swing bridge and therefore, cannot be replaced. It may also be preferred, if the drive shaft is an integral part of at least one of the two components of the oscillating body, wherein the drive shaft may be injection molded together with at least one of the two components, and wherein the drive shaft comprises an additional metal coating.

Both, the choice of material for each individual component of the swing bridge as well as the method of manufacture, should be chosen in accordance with the use of the swing bridge and in particular in accordance with the loads acting its individual components.

The swing bridge may be used within an electrically driven device to convert a rotary motion into an oscillating motion, especially into a linear oscillating motion. According to claim <NUM>, such an electrically driven device may comprise a housing with a chassis, an electric motor mounted in the chassis and comprising an eccentrically rotatable drive pin, and the swing bridge according to one of the before mentioned embodiments. The swing bridge is adapted to be mechanically coupled to the drive pin, and the drive pin extends into the slot of the swing bridge. Thus, the eccentrically rotary motion of the first pin is converted into a linear oscillating motion of the drive shaft by means of the swing bridge.

The housing may be formed by multiple components, which may be interconnected by common attachment means such as screws, hooks, glue, welding or the like. The same accounts for the chassis. In addition, the housing or some components of the housing and the chassis may be formed as one. The eccentrically rotatable drive pin may be an integral part of the drive shaft but may also be attachable to the drive shaft of the electric motor. Preferably, the eccentrically rotatable drive pin of the electric motor extends into the slot of the swing bridge. Consequently, when the slot comprises an elongated hole with its smaller widening in the longitudinal direction of the swing bridge, a rotation of the drive pin causes an at least substantially linear motion of the swing bridge in its longitudinal direction, when the swing bridge is secured by its webs to the housing and/or chassis. The conversion of a rotatable motion into a linear motion allows to use rotatable electric motors that are well-known, inexpensive and that comprise a high durability. Preferably, the electrically driven device further comprises a button in order to activate the device. The electrically driven device may be driven by at least one battery unit, wherein the battery unit is preferably rechargeable, and/or by a power connection to an electric socket. Additionally, the offset of the first axis and the second axis, i.e. the offset of the slot and the drive shaft, permit an asymmetric assembly of an electrically driven device, wherein a drive shaft of the electric motor does not need to be in line with the drive shaft of the swing bridge.

In one embodiment, the second axis may form a central axis of the housing and/or the chassis. Therefore, the drive shaft is arranged along the central axis of the housing and/or the chassis. According to the offset between the first and the second axis, the electric motor is consequently offset to the center of the housing and/or the chassis. Preferably, the electric motor is arranged on one side of the housing and/or the chassis. Further, at least one battery unit may be arranged on the opposite side of the housing and/or the chassis. The centered arrangement of the drive shaft allows to convert a rotational motion of an electric motor offset to the center of the housing and/or the chassis into a linear oscillating motion around the central axis of the housing and/or the chassis. Hence, a unit, such as a cutter unit, attached to the drive shaft may also be centrically driven.

Preferably, the two webs may be interconnected to the housing and/or the chassis, preferably by hot-staking. The two webs may also be interconnected to the housing and/or the chassis by other common connecting means such as by plug or clipped connection, by welding or the like. Due to the interconnection, the free end facing away from the oscillating body is fixed, wherein at least the oscillating body is free to move in its longitudinal direction. During the oscillating movement of the oscillating body, the webs are preferably bending back and forth. By interconnecting the at least one web to the housing and/or the chassis, the swing bridge is preferably secured so that a movement of the swing bridge is only permitted by one degree of freedom, i.e. a linear longitudinal oscillation. If the swing bridge is secured by hot-staking, the free ends of the webs may be pressed into press ribs, whereupon those ribs are melted by hot staking.

Further, a central axis of the electric motor may be arranged offset to the second axis. Preferably, the drive shaft of the electric motor runs along the central axis of the electric motor. Additionally or alternatively, it may be preferred if the central axis of the electric motor also forms the first axis.

In one embodiment, the electrically driven device may comprise a cap, wherein the cap is removably coupled to the housing, and wherein the put on cap is at least covering a button to actuate the electrically driven device. During the use of the electrically driven device the cap may be removed, while the cap may be attached to the electrically driven device doing storage and/or transportation. Thus, during storage and/or transportation the use of a cap can prevent an undesired activation of the device and/or an unwanted dirtying, for example an unwanted dirtying of a dopp kit by cut-off hair. Further, the cap may protect the electrically driven device against any ingress, for example dust ingress, and, therefore, may extend the durability of the electrically driven device.

The electrically driven device may further comprise at least one cutter unit, wherein the drive shaft may be mechanically coupled to the at least one cutter unit. The at least one cutter unit may comprise at least a slit cutter, wherein the slit cutter comprises at least an outer blade, preferably a foil-type blade, and an inner blade. Preferably, an oscillation of the inner blade is caused by the oscillation of the drive shaft of the oscillating body.

Furthermore, the electric motor may be sealed against undesirable environmental influences, such as moisture penetration, by at least one of the housing and/or the chassis and/or the cap. This is especially required when the electrically driven device is used within a wet environment such as a bathroom. The sealing of the electrically driven device and/or the moisture-sensitive components is effected by common means.

The invention will subsequently be explained in detail with reference to specific embodiments shown in the Figures. All features described and/or shown in the Figures are subject matter of the invention, irrespective of the grouping of the features in the claims and/or their back references.

The swing bridge <NUM> shown in <FIG> comprises an oscillating body <NUM> and a drive shaft <NUM>. The oscillating body <NUM> of <FIG> has an upper first component <NUM> and a lower second component <NUM>, wherein the first component <NUM> comprises a different shape than the second component <NUM>. The oscillating body <NUM> and the respective first and second component <NUM> and <NUM> are ultrasonic welded together and define plane X.

The swing bridge <NUM> further comprises two webs <NUM> being an integral part of the second component <NUM> of the oscillating body <NUM>. The two webs <NUM> each have a free end <NUM> facing away from the oscillating body <NUM>. To be bendable in a longitudinal direction, the webs <NUM> comprise in general a smaller material strength V compared to their width W. The width W of the webs <NUM> in the transverse direction shown in <FIG> is a bit smaller than the width of the components <NUM> and <NUM> of the oscillating body <NUM>. Additionally, the width W of the webs <NUM> between the oscillating body <NUM> and the free end <NUM> can differ. Further, the free ends <NUM> of <FIG> have protrusions facing away from the oscillating body <NUM> for securing the swing bridge <NUM>.

Furthermore, the second component <NUM> of the swing bridge <NUM> has a slot <NUM> (shown in <FIG>) with a first axis I, which runs through the center of the slot <NUM>. The drive shaft <NUM> is overmolded within a corner section of the first component <NUM> and runs along a second axis II. The two axes I and II are offset in two directions of the plane, i.e. a longitudinal and a transverse direction.

The section A-A of <FIG> is shown in <FIG>. Welding dots <NUM> in <FIG> are used for ultrasonic welding of the two components <NUM> and <NUM> of the oscillating body <NUM>. The first component <NUM> comprising the drive shaft <NUM> protrudes beyond the second component <NUM> in the longitudinal direction on the side where the drive shaft <NUM> is located. Moreover, the overmolding of the drive shaft <NUM> comprises ribs <NUM> for support on the first component <NUM>.

<FIG> shows a top view of the swing bridge <NUM>. It can be noticed that the first component <NUM> and the second component <NUM> are ultrasonic welded by four welding dots <NUM>. Even though it seems that the swing bridge <NUM> only comprises one web <NUM> on the left side, the web on the right side is simply covered by the protruding first component <NUM> as mentioned before. Further, the drive shaft <NUM>, which is located in a corner section of the oscillating body, is offset in two directions of the plane, wherein the offset in the longitudinal direction is bigger than the offset in the transverse direction of plane X.

In <FIG> a side view of the swing bridge <NUM> is shown, wherein the above-mentioned differing width W of the webs <NUM> can be noticed. The width W of web <NUM> is bigger at the free end <NUM> comprising the protrusion for securing the swing bridge <NUM>.

<FIG> shows an exploded view of the swing bridge <NUM> of <FIG> together with an electric motor <NUM>. The second component <NUM> shows the above-mentioned slot <NUM>. The slot <NUM> depicted in <FIG> is an elongated hole with a smaller widening in the longitudinal direction of the swing bridge <NUM>. The electric motor <NUM> comprises an eccentrically rotatable drive pin <NUM>. Once the swing bridge <NUM> and the electric motor <NUM> are assembled, the drive pin <NUM> extends into the slot <NUM> of the swing bridge <NUM>. Thus, a rotatable motion of the drive pin <NUM> can be converted into an oscillating motion of the swing bridge <NUM>. Especially when the swing bridge <NUM> is secured by the free ends <NUM> of the webs <NUM>, this oscillating motion is a linear oscillating motion in the longitudinal direction of the swing bridge <NUM> (neglecting the deflection in the direction perpendicular to plane X). The drive pin <NUM> may be coupled to a drive shaft <NUM> (shown in <FIG>) of the electric motor <NUM> or may be an integral part of the drive shaft <NUM>. Further, <FIG> depicts the offset between a drive shaft <NUM> of an electric motor <NUM> and the drive shaft <NUM> of the swing bridge <NUM> and, thus, shows an asymmetric assembly.

A chassis <NUM> comprising the assembled swing bridge <NUM> and electric motor <NUM> together with a battery unit <NUM> is shown in <FIG>. The chassis <NUM> is half-open. Hence, the rear wall is at least mostly closed. Additionally or as an alternative, the chassis <NUM> may be coupled to a housing or may be an integral part of a housing. The battery unit <NUM> is preferably rechargeable. Further, the free ends <NUM> of the swing bridge <NUM> are secured to the chassis <NUM>. One way to secure the swing bridge <NUM> to the chassis <NUM> is to press the free ends <NUM> of the webs <NUM> into press ribs of the chassis <NUM> and to melt those ribs by hot-staking. Once the swing bridge <NUM> is secured, only a movement of the oscillating body <NUM> is permitted. Further, due to the big width W of the webs <NUM> compared to their material strength V, the webs <NUM> are stiff in their transverse direction, while being flexible in their longitudinal direction. Thus, a linear oscillating motion of the swing bridge <NUM> is caused by a rotatable motion of the drive pin <NUM> extending into the slot <NUM> of the oscillating body <NUM>.

<FIG> illustrates an electrically driven device <NUM> comprising the assembled chassis <NUM> (not shown) of <FIG>. The electrically driven device <NUM>, here an electric shaver, comprises an upper housing <NUM>, an outer housing <NUM>, a button <NUM> and a cutter unit <NUM>. The upper housing <NUM> includes the button <NUM>. The button <NUM> is used to actuate the electrically driven device <NUM>.

A cross-sectional view of the electrically driven device <NUM> is shown in <FIG>. The electric driven device <NUM> comprises the chassis <NUM> and the cutter unit <NUM>. The chassis <NUM> is fixed within the housing and comprises the swing bridge <NUM>, the electric motor <NUM> and the battery unit <NUM>. The electric motor <NUM> is arranged on the left side of the electrically driven device <NUM> and the battery unit <NUM> is arranged on the right side of the chassis <NUM> as seen in <FIG>. Hence, the assembly of the electric motor <NUM> and the battery unit <NUM> is asymmetric according to the drive shaft <NUM> of the swing bridge <NUM>.

The electric motor <NUM> comprises a drive shaft <NUM> and an attachable eccentrically rotatable drive pin <NUM>. The drive pin <NUM> extends into the slot <NUM> and mechanically couples the electric motor <NUM> to the swing bridge <NUM>, wherein the swing bridge <NUM> is secured within an outer and an interior wall of the chassis <NUM>. As can be seen from <FIG>, the drive pin <NUM> extends through slot <NUM> of the second component <NUM> and protrudes into a recess of the first component <NUM>. Further, drive shaft <NUM> of the swing bridge <NUM> is mechanically coupled to the cutter unit <NUM>.

Additionally, the electrically driven device <NUM> comprises multiple housing parts, i.e. the upper housing <NUM>, the outer housing <NUM>, a lower housing <NUM> and an inner housing <NUM>. All housing parts <NUM>, <NUM>, <NUM> and <NUM> and the chassis <NUM> are coupled by attachment means such as hooks, screws or the like. Further, the upper housing <NUM> comprises a softer material than the inner housing <NUM>. In order to prevent the inner component parts of the electrically driven device <NUM> to be wetted, especially the electric motor <NUM> and the battery unit <NUM>, the housing parts and/or the chassis are sealed by seals <NUM>.

Additional seals <NUM> can be seen in an exploded view of the electrically driven device <NUM> in <FIG>. Furthermore, <FIG> shows a cap <NUM> that can be attached to the electrically driven device <NUM> during storage and/or transport. The dotted lines in <FIG> demonstrate the way of assembly of some housing components and seals <NUM> to the chassis <NUM>.

The assembled exemplary electrically driven device <NUM> with the electric motor <NUM>, the battery unit <NUM>, the swing bridge <NUM> and the cutter unit <NUM> is therefore adapted to convert the rotatable motion of the drive shaft <NUM> of the electric motor <NUM> into a linear oscillation of the drive shaft <NUM> and thus to operate the cutter unit <NUM>. Therefore, the swing bridge <NUM> converts the rotatable motion of the drive shaft <NUM> of the electric motor <NUM> and the respective eccentrically drive pin <NUM> into a linear oscillating motion of the drive shaft <NUM> and thus the cutter unit <NUM>.

When the electrically driven device <NUM>, i.e. the electric motor <NUM>, is actuated by button <NUM> and the battery unit <NUM> powers the electric motor <NUM>, the drive shaft <NUM> starts rotating. The drive pin <NUM>, which is attached to the drive shaft <NUM> converts the rotatable motion into an eccentrically rotatable motion. As the drive pin <NUM> extends into slot <NUM>, i.e. an elongated hole with its smaller widening in the longitudinal direction of the swing bridge <NUM>, a full rotation of the drive pin <NUM> may first push the swing bridge <NUM> in the longitudinal direction to its right side, wherein the webs <NUM> bent and only the oscillating body <NUM> of the swing bridge <NUM> is shifted. Since, the drive pin <NUM> continues to rotate, the drive pin <NUM> reaches the bigger widening of the elongated hole, followed by a push of the swing bridge <NUM> in the opposite direction, i.e. to the left side. Between the transition of the movement of the swing bridge from the right to the left, the webs <NUM> relax before they are bent again. As the rotatable motion of the drive pin <NUM> continues, the swing bridge <NUM> and therefore the drive shaft <NUM> continues to oscillate in its longitudinal direction, which operates the cutter unit <NUM>.

As the swing bridge <NUM> enables an offset between the drive shafts <NUM> and <NUM>, the electric motor <NUM> can be assembled within the electrically driven device <NUM> in an edge portion, close to the side walls of the chassis and/or the housing. Hence, space for a battery unit <NUM> on the side opposite to the electric motor <NUM> is created and the use of the available installation space can be optimized.

Consequently, the use of the inventive swing bridge <NUM> is particularly suitable for small electrically driven devices.

Claim 1:
A swing bridge for converting a rotary motion into an oscillating motion, especially into a linear oscillating motion, comprising
an oscillating body (<NUM>) defining a plane (X), the oscillating body (<NUM>) comprising a slot (<NUM>) arranged in the plane (X), wherein a first axis (I) extends through the center of the slot (<NUM>) perpendicular to the plane (X), and a drive shaft (<NUM>) protruding perpendicular to the plane (X) along a second axis (II), two webs (<NUM>) extending at least substantially perpendicular to the plane (X), each web (<NUM>) having a free end (<NUM>) facing away from the oscillating body (<NUM>) for securing the oscillating body (<NUM>) to permit movement of the oscillating body (<NUM>) substantially only parallel to the plane (X), and wherein the first axis (I) and the second axis (II) are offset at least in one direction of the plane (X) characterized in that the second axis (II) is located in a corner section of the oscillating body (<NUM>).