Patent Application
20110285391
The present invention relates to balls having at least one magnetic field sensor provided therein for determining a magnetic field in the ball centre of gravity, and to a method of manufacturing said balls.
For measuring the position of a ball, it was suggested in the prior art to provide in said ball a magnetic field sensor measuring an artificially created magnetic field, with the known correlation between magnetic field propagation and magnetic field strength permitting determination of the position of the ball.
As the ball during movement thereof typically can move about its own axis, it is advantageous to fix the sensor in the centre of gravity of the ball. To this end, it has already been suggested in the prior art to suspend a magnetic field sensor in the ball's centre by means of a plurality of threads.
This is problematic insofar as such rigid tensioning results in very high acceleration forces being exerted on the sensor when the ball is kicked hard, e.g. during a soccer game.
It is therefore the object of the present invention to develop an improved device for measuring a magnetic field in the centre of gravity of a ball.
This object is achieved by the subject matters of the independent claims.
Preferred embodiments are subject matter of the dependent claims.
The elastic fixation of at least one magnetic field sensor, according to the invention, is based on the finding that, on the one hand, the magnetic field sensor preferably is to be provided in the ball's centre of gravity while, on the other hand, the magnetic field sensor may suffer damage by excessively high acceleration forces.
An advantageous aspect of a preferred embodiment of the present invention thus is based on that a magnetic field sensor is fixed substantially in the centre of gravity of a ball by soft elastic foam, thereby attenuating rapid accelerations on the one hand while avoiding large deflection of the magnetic field sensor on the other hand.
A further advantageous aspect of a preferred embodiment of the present invention is based on that a magnetic field sensor is elastically fixed substantially in the centre of gravity of the ball by a plurality of springs, thereby attenuating rapid accelerations on the one hand while avoiding large deflection of the magnetic field sensor on the other hand. Still another advantageous aspect of this preferred embodiment, as compared to the prior art, is to be seen in that the springs adjust optimally to ball deformations, thus avoiding that the magnetic field sensor impinges on the inner wall of the ball and is damaged thereby.
Still another advantageous aspect of a preferred embodiment of the present invention is based on that a magnetic field sensor is provided in the middle of the flat sides of two hemispherical balloons and thus is elastically fixed substantially in the ball's centre of gravity, thereby attenuating rapid accelerations on the one hand while avoiding large deflection of the magnetic field sensor on the other hand. An additional advantageous aspect of this preferred embodiment, as compared to the prior art, is to be seen in that balloons in balls have been successfully employed for years and, thus, existing methods of manufacturing balls need to be modified only slightly.
A further advantageous aspect of a preferred embodiment of the present invention is based on that a magnetic field sensor is provided on a plurality of spherical-wedge-shaped balloons such that the magnetic field sensor is fixed elastically in the centre of gravity of a spherical balloon, so that rapid accelerations are attenuated on the one hand while large deflection of the magnetic field sensor is avoided on the other hand.
A still further advantageous aspect of a preferred embodiment of the present invention resides in that two magnetic field sensors are provided opposite one another on the inside of a ball, so that fixation in the ball's centre of gravity is rendered superfluous. The magnetic field value in the ball's centre of gravity will then be calculated preferably by interpolation.
In the following, preferred embodiments will be explained in more detail with reference to the attached drawings, wherein
Prior to foam-filling of the ball (100), the magnetic field sensor (110), preferably by means of a plurality of thin plastics threads (140) which are preferably symmetrically attached to the inner wall (150) of the ball and are of equal lengths, is tensioned such that it is fixed substantially in the centre of gravity (130) of the ball (100). The ball (100) is then filled completely with foam (120).
In accordance with a preferred embodiment of the present invention, the foam (120) is a soft foam. In a particularly preferred embodiment of the present invention, the foam is soft polyurethane foam.
In order to affect the elasticity of the ball (100) as little as possible, it is important for the foam (120) to be of low density. The foam (120) preferably has a density of less than 10 kg/m3. For being able to change the internal pressure of the ball (100), preferably open-pore foam is utilized and a valve (160) is provided in the ball wall. In a preferred embodiment of the present invention, polyether foam is used.
The tensile strength of the attaching threads (140) preferably is selected such that they do not withstand rapid accelerations of the ball (100) so that, upon complete reaction of the foam (120), the magnetic field sensor is fixed in the centre of gravity of the ball (100) solely by the completely reacted foam (120).
For transferring the sensor values measured, the sensor (110) is connected to a transmission unit, preferably a radio transmitter. The radio transmitter operates preferably in the 2.4 GHz range.
For supplying power to the magnetic field sensor (110), an accumulator or battery is provided according to a preferred embodiment of the present invention. Said battery is preferably rechargeable via induction coils.
In accordance with an alternative embodiment, no battery is provided and the magnetic field sensor (110) and the radio transmitter make use of induction energy.
For preventing damage to the inside of the ball (200) by sharp edges, a plastics cap (240) is provided on each spring end according to a preferred embodiment of the present invention.
During manufacture of the ball (200), the springs (220) preferably are wrapped around the magnetic field sensor (210), fixing the latter in this state. After inflation of the ball (200) via valve (250), the fixations are released, with the elasticity of the springs (200) having the effect that the magnetic field sensor (210) is fixed substantially in the centre of gravity of the ball (200). To this end, preferably springs (200) of equal lengths are selected.
In accordance with a preferred embodiment of the present invention, fixation is obtained by means of a temperature-sensitive polymer, which permits release of the fixation by heating. In accordance with a specially preferred embodiment, the polymer is a low-temperature thermoplastic material having a melting temperature below 50° C.
For transmitting the measured values of the magnetic field sensor (210), the latter is connected to a transmission unit, preferably a radio transmitter. The radio transmitter operates preferably in the 2.4 GHz range.
For supplying power to the magnetic field sensor (210), a battery is provided according to a preferred embodiment of the present invention. Said battery is preferably rechargeable via induction coils.
In accordance with an alternative embodiment, no battery is provided and the magnetic field sensor (210) and the radio transmitter make use of induction energy.
During manufacture of the ball (300), the magnetic field sensor (310) is connected to both of the hemispherical balloons (330) (340) and introduced into the ball (300). Both balloons (330) (340) are connected to a valve (350) permitting inflation of the two balloons (330) (340) to the same pressure. By fixation of the magnetic field sensor (310) in the middle of the flat side of both balloons (330) (340), it is ensured that the magnetic field sensor (310) is fixed substantially in the centre of gravity of the ball (300).
In an alternative embodiment of the present invention, both of the hemispherical half-balloons have perforations on their flat sides, with the two hemispherical half-balloons being adhered to each other such that the two hemispherical balloons are connected to each other by the mutual perforations.
For transmitting the measured values of the magnetic field sensor (310), the latter is connected to a transmission unit, preferably a radio transmitter. The radio transmitter operates preferably in the 2.4 GHz range.
For supplying power to the magnetic field sensor (310), a battery is provided according to a preferred embodiment of the present invention. Said battery is preferably rechargeable via induction coils.
In accordance with an alternative embodiment, no battery is provided and the magnetic field sensor (310) and the radio transmitter make use of induction energy.
In accordance with a preferred embodiment, the spherical-wedge-shaped balloons (420) are flattened on their pointed side, thereby creating a duct transversely through the spherical shape formed by the plurality of the spherical-wedge-shaped balloons (420). The magnetic field sensor (410) is introduced in said duct preferably prior to inflation of the balloons (420). After inflation of the balloons (420), the magnetic field sensor (410) is fixed substantially in the centre of gravity of the ball (400).
The modular disc (510a) on the valve carries, in addition to the magnetic field sensor, a radio transmitter with antenna as well as a CPU. On the opposite modular disc (510b), there is provided the battery (520) which is attached such that it is located on the side facing the interior of the ball.
In accordance with an alternative embodiment, no battery is provided and the magnetic field sensor and the radio transmitter make use of induction energy.
The measured values of both sensors are utilized to determine the expected measurement value in the centre of the ball (500). With respect to the magnetic field strength, this is achieved preferably by simple averaging.
In accordance with a specially preferred embodiment of the present invention, both modular discs (510) are connected to flexible circuit boards.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2008 052 215.5 | Oct 2008 | DE | national |
This application is a National Phase entry of International Patent Application No. PCT/EP2009/007449 filed 16 Oct. 2009, which claims priority to German Patent Application No. 10 2008 052 215.5 filed 17 Oct. 2008, each of which are incorporated herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/007449 | 10/16/2009 | WO | 00 | 8/9/2011 |
