The present invention relates to a sports shoe comprising a sole provided with a grip enhancing structure.

To increase the grip of a shoe on a surface, i.e. the ground, it is common in sports to provide shoes with a grip enhancing structure, for instance in the form of studs. The arrangement or structure of the studs may be optimized to provide optimal grip for various movements of the athlete.

For instance during a turn, it may be advantageous to have a decreased grip for one shoe, allowing easy rotation around the foot. It was believed that this decreased grip would reduce injuries to for instance the knees and ankles.

It is therefore known to optimize the arrangement of the studs to allow this decreased grip during a turn. It is further suggested to provide the sole of a sports shoe with rotating parts, for instance is the form of rotating studs or rotating sections provided with a plurality of studs.

However, these solutions still resulted in knee and ankle in uries .

It is therefore goal of the present invention, amongst other goals, to provide a safe and/or efficient sports shoe. The above goal is met by the present invention, amongst other goals, by a sports shoe as defined in the appended claim 1. Specifically, the above goal, amongst other goals, is met by the present invention by a sports shoe comprising a sole provided with a grip enhancing structure, wherein the shoe comprises at least one detector arranged for detecting movement of said shoe and a processor, wherein the grip enhancing structure is moveable between an increased

gripping state and a decreased gripping state, wherein the processor is arranged to move the grip enhancing structure between the states based on the detected movement by said detector. By detecting the movement of a sports shoe and adapting the grip to said detected movement, an optimal grip can be provided for said movement. The detector can comprise an acceleration detector and/or a positional detector. The detector may also be arranged to detect the intention of a movement, for instance by detecting and measuring the pressures of the foot on the sole.

The grip of the sole on a surface, in particular the ground, may be increased or decreased by adjusting the stiffness of at least a part of the material of the grip enhancing surface. It is however also possible to adjust the grip by changing the structure and/or shape of the grip enhancing structure, for instance by rearranging the studs or by changing the shape of the studs .

It should be noted that although an increased and decreased gripping state are described, it is also possible to adjust the gripping to a state of gripping in between said two mentioned states. The grip enhancing structure may hereto have variable gripping capacities. The processor may

therefore be arranged to adjust the gripping of the grip enhancing structure based on the movement detected by the detector. It may for instance be possible to relate the amount of generated grip to the speed of the measured movement .

It should further be noted that with grip, the mechanical resistance between the sole and a surface, for instance the ground, is meant. The grip of the grip enhancing surface can be different for different directions. By detecting the movement of the shoe, the grip can be enhanced for different movements .

According to a preferred embodiment of the sports shoe according the invention, the detector is arranged to detect a movement with a component in a plane substantially

parallel to the plane of the sole. The grip of the grip enhancing structure can then be adjusted based on the movement of the shoe, for instance a sideways or forward motion .

According to a further preferred embodiment of the sports shoe according the invention, the detector is arranged to detect at least one of a rotational or a translational movement of said shoe, wherein the processor is arranged to move the grip enhancing structure to the increased gripping state upon detection of a translational movement and/or wherein the processor is arranged to move the grip enhancing structure to the decreased gripping state upon detection of a rotational movement. The processor is hereby arranged to provide a decreased grip when a rotation is detected. This allows easy turning for the athlete around said shoe. When a translational movement is detected, the grip is enhanced by the processor. With a rotational movement, a rotational movement around an axis perpendicular to the sole and therefore the underground is meant. When an athlete initiates a turn around said shoe, the processor is arranged to move the grip enhancing

structure to the decreased gripping state, facilitating the initiated turn. A translational movement is a movement substantially straight in the plane parallel to the sole and therefore the surface. When the athlete for instances initiates a forward or sideway movement, the grip enhancing structure is moved to the increased gripping state, allowing the athlete to exert more power during the initiated

movement .

According to a further preferred embodiment of the sports shoe according the invention, the grip enhancing structure is further moveable to an intermediate gripping state. The processor can for instance be arranged to move the grip enhancing structure to the intermediate state when no translational or rotational movement is detected.

According to a further preferred embodiment of the sports shoe according the invention, the processor is arranged to hold the grip enhancing structure in a resting state chosen from one of the states of the grip enhancing structure, wherein the processor is arranged to move the grip enhancing structure to another state upon detection of a movement by the detector. The grip enhancing structure is hereby in its resting state, unless a movement is detected. The resting state may be induced by the processor or more preferably the resting state is the natural state of the grip enhancing structure. When no signals are provided to the grip

enhancing structure, the grip enhancing structure assumes its resting state. It can be advantageously when the increased gripping state is the resting state. The detector may then me arranged to only detect a rotational movement. In case a rotational movement is detected, the processor is arranged to move the grip enhancing structure to the decreased gripping state. After the rotational movement, the grip enhancing structure moves back to the resting state, in this case the increased gripping state.

According to a further preferred embodiment of the sports shoe according to the invention, the detector extends on the sole, wherein the detector is arranged to detect movement between the sole and a surface, in particular the ground. Detecting movement between the ground and the sole results in an accurate measurement of the movement of the shoe and allows efficient adaptation of the grip enhancing structure to said movement. The detector may for instance comprise a visual or a force detecting detector.

According to a further preferred embodiment of the sports shoe according to the invention, the detector is arranged to detect deformation of at least a part of the grip enhancing structure. Deformation of the grip enhancing structure is a good predictor of the initiated movement of the shoe. More preferably, the detector is arranged to detect a component of a deformation force parallel to the plane of the sole.

More preferably the sole comprises at least a first and a second detector, wherein the detectors are arranged to detect respectively a first and a second direction of movement of the shoe, and wherein the detector is arranged to detect a translational movement if the first direction is substantially equal to the second direction and/or wherein the detector is arranged to detect a rotational movement if the first and second direction are substantially different. By detecting the direction of movement of the shoe on two locations, it can be established whether a translat ional movement or a rotational movement is made by the shoe. In case of a translational movement, the directions of movement of two points of the shoe, preferably the movement of the sole with respect to the ground, are substantially equal. On the other hand, when differing or even opposite directions are measured, the shoe is a rotating movement.

According to a further preferred embodiment of the sports shoe according the invention, the detector comprises at least one piezoelectric element in the grip enhancing structure. Piezoelectric elements, preferably piezoelectric fibres, are capable of generating electrical signals upon deformation. The electrical signals are provided to the processor. Preferably a detector comprises a plurality of piezoelectric elements, allowing the direction of the movement to be detected. The orientation of the elements may hereto be varied.

It should be noted that although piezoelectric elements are used for measuring deformation and thereby the movement of the shoe, it may also be possible to use similar elements which are arranged to generate electric signals due to mechanical changes, in particular strain. According to the invention, the piezoelectric elements in the grip enhancing structure are arranged to generate electrical signals as a result of the movement between said structure and a surface, wherein the processor is arranged to determine the movement of the shoe using said electrical signals .

The generated electrical signals due to the deformation of the piezoelectric elements may be used to power for instance the processor. It is however also possible to provide a separate power source, for instance in the form of a battery . According to a further preferred embodiment of the sports shoe according the invention, the grip enhancing structure comprises studs, wherein at least two of the studs are provided with at least one detector. This results in a reliable determination of the movement of shoe. Preferably, a stud comprises a plurality of piezoelectric elements arranged to detect a direction of movement by the

deformation of said stud.

According to a further preferred embodiment of the sports shoe according the invention, the grip enhancing structure comprises at least one piezoelectric element, wherein the processor is arranged to supply electrical signals to said piezoelectric element for moving the grip enhancing

structure between the states. Piezoelectric elements are capable to induce deformation when an electrical signal is supplied. The processor is hereto arranged to provide said electrical signals to induce the deformation of the

piezoelectric element on basis of the detected movement. More preferably electric signals are provided to a plurality of piezoelectric elements provided in the grip enhancing structure . Using piezoelectric elements to change the gripping

capacities of the grip enhancing structure results in an efficient and reliable shoe compared to for instance the rotating parts known in the art, which are mechanically complex and therefore susceptible to damage and wear.

The processor may be provided with a power source, for instance in the form of a battery, to be able to supply the electrical signals. It may also be possible that the

electrical signals generated in the piezoelectric elements of the detector are used to supply the electrical signals to the piezoelectric elements for changing the gripping state.

The resting state of the grip enhancing structure is

preferably the state of said structure wherein no electrical signals are provided to the piezoelectric elements. A power efficient shoe is hereby provided. Upon a detected movement, the grip enhancing structure may be moved to another

gripping state.

Although it may be possible to move between the increased and decreased gripped states by using a single piezoelectric element or a group of piezoelectric elements, it may also be possible to provide in a plurality piezoelectric elements, wherein each piezoelectric element is arranged to move the grip enhancing structure to a different state. It may for instance be possible to change the gripping capacities of the structure by supplying more or less piezoelectric elements or groups thereof with electrical signals. It may also be possible to use different piezoelectric elements to move to the increased or decreased gripping states.

Supplying an electrical signal to a first piezoelectric element may move the structure to the increased gripping state, while supplying an electrical signal to a second piezoelectric element may move the structure to the

decreased gripping state. Supplying no signals may leave the structure in the resting state, as an example.

Preferably the piezoelectric element is arranged to change the mechanical properties of the grip enhancing structure upon receipt of electrical signals supplied by the

processor. The elements can hereto be arranged to increase the stiffness of for instance a stud provided with said elements. By increasing the stiffness, the grip is

increased, thereby moving the grip enhancing structure to the increased gripping state. More preferably the piezoelectric element is arranged to change the structural properties of the grip enhancing structure upon receipt of electrical signals supplied by the processor. The deformation of the piezoelectric element may for instance change the orientation of a stud or a plurality of studs, changing the grip of said grip enhancing

structure .

According to a further preferred embodiment of the sports shoe according the invention, the piezoelectric element comprises at least one piezoelectric fibre. More preferably a plurality of fibres is provided allowing an efficient modification of the gripping capacity of the grip enhancing structure based on the detected movement. Suitable

piezoelectric fibres are known, for instance in the form of Active Fibre Composites.

The present invention is further illustrated by the

following Figures, which show a preferred embodiment of the device according to the invention, and are not intended to limit the scope of the invention in any way, wherein:

- Figure 1 schematically shows a sports shoe according to the invention;

- Figure 2 schematically shows the sole of the sports shoe ; - Figures 3, 4a and 4b schematically show the detectors, and;

- Figures 5 and 6 schematically show studs of the shoe according to the invention.

In figure 1 a soccer shoe 1 according to the invention is shown. The shoe 1 is provided with a sole 2 provided with a grip enhancing structure in the form of studs 3. The sole 2 is shown in more detail in figure 2.

As shown, the sole 2 comprises a plurality of studs 3, whereby studs 31, 32 and 33 are separately indicated. The sole is furthermore provided with a processor 4 and a battery (not shown) . Each of the studs 3 is connected to the processor 4 using electrical wires, whereby wires 81, 82 and 83 are indicated.

In this example, studs 31 and 32 are provided with detectors to detect the movement of the shoe 1 in the plane parallel to the ground. More particularly, the detectors are arranged to detect a deformation or deflection of the studs 3 due to an initiated movement of the shoe 1 with respect to the ground . In figure 3 an example is shown wherein a single stud 31 comprises a first detector 51 and a second detector 52.

Detectors 51 and 52 comprise a plurality of piezoelectric fibers as will be explained more in detail below. The detectors 51 and 52 are each arranged to detect a direction of movement, indicated with the arrows.

Since first detector 51 detects a direction to the left while second sensor 52 detects a direction to the right, it is detected that a rotational movement I is initiated by the shoe 1.

Figure 4a shows an example wherein each of the studs 31 and 32 are provided with a single detector 51 respectively 52.

In this example, both detectors 51 and 52 detect a direction of movement in the same direction. It is therefore detected that a translational or rectilinear movement II is initiated by the shoe 1. In figure 4b, the detectors of the studs 31 and 32 detect different directions, indicating a rotational movement III. It will be appreciated that not only the type of movement, i.e. rotational or translational , can be detected, but also the direction of said movement by efficient placement of the detectors.

In figure 5 a stud 3 is shown in cross-section. The stud 3 is provided with a plurality of piezoelectric fibers 6. In case the stud 3 is arranged to function as a detector, fibers 6 will generate an electrical signal due to

deformation, indicated with IV. Fiber 61 will be compressed while fiber 62 will be elongated. Each of the fibers 6 is connected to the electrical wire 8 for transmittal of the generated signals to the processor 4. In order to detect directions of deflection, the stud 3 is provided with a plurality of fibers 6 with different orientations. Each fiber may be provided with a single wire 8 to allow readout of each individual fiber 6.

Stud 3 from figure 5 may also function to change the

gripping capacity of the grip enhancing structure of the shoe 1. By supplying electrical signals through wire 8 to fibers 8, the properties of the stud 3 may be altered. In this example the stud 3 is arranged to retract on the supply of electrical signals due to the piezoelectric fibers 6. It is however also possible to increase the stiffness of the stud 3 using piezoelectric elements. The stud shown in figure 6 is arranged to rotate around axis X on supply of electrical signals. A piezoelectric element 7 may therefore be arranged. Rotation of the stud 3 and more particular the rotation of a plurality of studs 3 change the structure of the grip enhancing structure, thereby changing the gripping capacities.

In case a rotational movement is detected, as shown for instance in figure 3, the processor is arranged to send signals to a plurality of studs 3 to for instance decrease the stiffness of the studs 3. The shoe 1 is now allowed to rotate efficiently. In case a translational movement is detected, for instance as shown in figure 4a, the processor instructs the studs 3 to increase the stiffness, creating more grip for the athlete to exert power.

The present invention is not limited to the embodiment shown, but extends also to other embodiments falling within the scope of the appended claims. It should hereby be noted that although studs are described as gripping enhancing structure, the current invention is also applicable to for instance shoes provided with profile. Changing for instance the height or the stiffness of the profile may therefore change the gripping capacities.