The present invention relates to a device for determining a ball impact in the corner between a wall and the ground, more specifically for determining the sequence in which a ball hits a first wall and a second wall, said walls at least partly delimiting a playing field of a ball sports court. More specifically, the device relates to a padel court for detecting a so-called "Bola Huevo" situation.

Padel is a racket and ball sport, whereby a ball, similar to a tennis ball, needs to be played over a net with a racket. It is mix between tennis and squash. Padel courts, as shown in figure 1, have three-metre high concrete or glass walls (backwalls and sidewalls). On both lateral sides there is a 12 metre long fencing (metal), with at least a door on one side in the middle.

In padel the ball must be hit over the net on the opponent's half, without the ball first hitting one of the walls. The aim is to prevent the opponent from hitting the ball back. However, the ball remains in play when said ball first hits the ground and then one of the walls.

The "Bola Huevo" term is used when the ball is hit toward the sideline or baseline and bounces in the corner between the vertical wall of the glass or fencing and the ground, without it being clear whether the ball first hit the wall or the ground. This can be the backwall or sidewall. It is an anomalous, but frequently occurring situation, that raises doubts and insecurities and usually gives rise to discussion between the players to determine whether it is a valid point or not.

Generally, the following logical explanation is taken into account. If the ball rebounds from the corner in a higher direction than the incoming direction, it hit the ground first. If the ball rebounds from the corner in a lower direction than the incoming direction, it hit the glass or the fencing first.

A second applied way to determine whether the ball first hit the wall or the ground, as shown in figure 2, is based on the observation of the direction of rotation or spin of the ball when rebounding from the corner.

If the ball rebounds from the corner with backspin, shown in figure 2 with the counter-clockwise arrow seen from the adopted point of view, the conclusion is that the ball first hit the ground and was therefore correctly played. Reversely, when the ball rebounds from the corner with top spin, shown in figure 2 with the clockwise arrow seen from the adopted point of view, the conclusion is that the ball first hit the wall and was therefore incorrectly played.

It is understood that both methods are not really convincing and lead to discussions, with serious consequences professionally and for umpires in official matches, especially concerning sponsoring, ranking etc. Known systems for detecting a ball, as applied in tennis, show the disadvantage that they require complex and/or intensive data processing or video images. Other systems require a sensor in the ball.

The purpose of the present invention is to provide a solution to at least one of the aforementioned and other disadvantages. In particular the invention aims at offering a solution in a simple manner and with very little need for data processing.

To this end, the invention relates to a device for determining the sequence in which a ball hits a first wall and a second wall, said walls at least partly delimiting a playing field of a ball sports court, whereby the first wall is for example a glass wall or fencing and the second wall, for example the ground, said device comprising at least two sensors and a processing unit, whereby the first sensor provides for first sensor field, for example a first sensor line or sensor strip, and whereby the second sensor provides for a second sensor field, for example a second sensor line or sensor strip, whereby the first sensor field is provided at least partly at a first distance from the first wall and at least partly in the playing field, and whereby the second sensor field is provided at least partly at a second distance from the second wall and at least partly in the playing field, whereby the smallest distance between the first sensor field and the second sensor field is not bigger than 150% of the diameter of the ball. Sensor field relates to the spatial volume in which the presence of an object activates the sensor. Said spatial volume can be a line or a strip, but also a cone or any other shape.

For the sake of readability, sensor line or sensor strip will be used hereinafter to replace the term sensor field. These terms also refer to a sensor field, unless it is explicitly indicated that it relates to a narrower interpretation .

Upon detecting the passage of a ball across a sensor field, the sensor generates a detection signal that is transmitted to the processing unit.

The processing unit can receive the detection signals and is designed such that it can determine the sequence of receipt of detection signals and generate an output-signal depending on the determined sequence.

It is important to realise that it is not necessarily the contact with the walls nor the moment the ball hits the walls that is measured.

If the sensor line or sensor strip is located at a distance from the wall, the "contact moment" of the ball with the sensor line or sensor strip is measured.

Because the sensor line or sensor strip is provided in mid air in that case and not on a tangible element, we often refer to the passage of the ball across the sensor line or sensor strip.

The first distance between the first sensor line or first sensor strip and the first wall, and also the second distance between the second sensor line or second sensor strip and the second wall, and also the relative distance between the first sensor line or first sensor strip and the second sensor line or second sensor strip are deliberate and chosen such that the indirect measurement still offers a correct and reliable evaluation of the sequence of contact moments of the ball with walls.

The purpose of the invention is to determine the sequence in which a ball hits a first and a second wall. When a balls passes across, or touches, a sensor line or sensor strip, the sensor will detect an interruption of the sensor signal.

In the case the sensor field relates to a sensor strip, which means a substantially flat band with a constant or variable width, said sensor strip can of course be provided parallel to or on a wall but also at a different angle

Preferably, the smallest distance between the two sensor lines or strips is less than or equal to the diameter of the ball. Consequently it is possible to unambiguously detect whether a ball that bounces in the corner of two walls, for example in the corner of a vertical wall and the ground, first hits the ground and then the vertical wall or vice versa.

In a padel court the vertical wall can, for example, be a vertical glass backwall at the back of the playing field, i.e. the wall away from the playing net.

Alternatively, in a padel court the vertical wall can, for example, also be a vertical sidewall on the sides of the playing field. Said sidewalls are partly constructed in glass at the bottom and partly made of fencing.

Consequently it is possible to unambiguously detect a "Bola Huevo" situation.

In a specific embodiment, as in the case of a flat strip, the strip is located parallel to the relevant wall.

In a specific embodiment, the sensor line or strip which is provided near the ground is provided parallel to the sidelines or baselines of the playing field.

In a preferred embodiment, the at least two sensors comprise at least one of the following sensors:

- optical or motion sensors;

- pressure sensors;

- vibration sensors.

In a preferred embodiment, at least one of the sensors is an optical sensor based on laser technology, whereby a laser line or laser strip is generated. In a preferred embodiment, the laser line will not be visible to the naked eye.

In another preferred embodiment, at least one of the sensors is a pressure sensor which is based on a pressure sensitive conductive plate, whereby a pressure sensitive strip is generated. The first distance (dl) between the first wall and the pressure sensor is hereby equal to zero or the second distance (d2) between the second wall and the pressure sensor is hereby equal to zero.

Preferably, the first sensor is a pressure sensor and the second sensor an optical sensor.

The pressure sensor is hereby thus provided on the wall and the optical sensor at a certain distance d2 above the ground.

This has the advantage that the error margins in this embodiment can be made as small as possible. A "blind spot" between the first sensor and the back wall is reduced to zero in this way.

The sidelines and baselines of a playing field can be provided with sensor lines via sensors arranged in the corners of the field. Other arrangements also are within the scope of this invention. In a specific arrangement, a sensor line can be sent via a sensor across one or more successive sidelines and/or baselines via one or more reflectors or mirrors arranged in the corners of the playing field. Consequently, fewer sensors are required. In a preferred embodiment the processing unit generates a different outgoing signal depending on whether the first sensor or the second sensor first detects a signal, in other words depending on whether the ball first hits the first wall or first the second wall.

In another preferred embodiment the processing unit generates a different outgoing signal based on at least two detection signals, a first signal of the first sensor, when the ball hits the first wall, and a second signal of the second sensor, when the same ball hits the second wall.

Consequently, the sequence of both signals can be determined by the processing unit.

The relevant sensor detects "whether the ball hits a wall" when the ball interrupts or passes the relevant sensor line or strip. In that case the sensor will generate a detection signal.

In a preferred embodiment the processing unit generates an output in the form of a visual signal or a sound depending on the detected or generated signals.

In another preferred embodiment the at least two sensors can perform smart measurements, such as for example a height measurement of the trajectory of the ball of the incoming and rebounded ball. Such smart measurements can contribute to a possible error correction or extra measurement parameters. Consequently, the processing unit can apply error correction or process extra measurement parameters .

Error correction may be important to exclude deviating measurements. Such measurements can be caused by a false detection of particles such as, among others, gravel, grains of sand, blades of grass, dust, etc. Such particles may be blown up by the impact of the ball on the ground, or they may be present on the ball and become detached on impact. Preferably, the error margin of the sensor is such that only sufficiently big elements are detected.

Error correction or additional measurements can be performed with software, extra sensors and/or camera monitoring and processed in the processing unit.

In an alternative embodiment, the sensors can determine the time of detection to, for example a tenth or hundredth of a second and the sequence of the impact of the ball is determined by comparing detection times.

Preferably, the processing of signals is done in real-time or within an acceptable time frame. This means the players do not have to wait unduly long periods of time for the output of the processing unit.

The sensors and processing unit provide a certain accuracy for measuring/detecting and processing.

If the processing unit cannot determine an unambiguous sequence within the limits of accuracy, or if the sensors detect an unacceptable error margin, a specific output signal can be generated. The ball will have to be replayed in this case.

The processing unit may comprise software for visualising the line of the ball in a "Bola Huevo" situation. This can be used as output for spectators for example. This can be done in a simple way or more truthfully and based on additional measurements and/or calculations.

By detecting, for example, the time of interruption of a sensor line, extra information can be derived, such as for example which part of the ball crossed the line. A shorter interruption will usually indicate a smaller part of the ball that crossed the line.

In another embodiment, the processing unit is provided with artificial intelligence (AI). The input of such AI algorithms comprises the detected signals but can also comprise extra measurement data such as among others, the angle of impact and of rebound, the speed of the ball, etc. Based on certain saved ball situations and ball trajectories, the algorithm can learn and quickly recognise new situations.

Preferably, the arrangement of the sensors and/or other measuring equipment will be done in a calibrated way.

The processing unit comprises software for processing the signals detected by the at least two sensors in one or more output signals. The output can comprise sound signals or visual signals, such as for example LED. The output can also be in the form of statistical information and information based on smart measurements.

In a preferred embodiment the walls of a playing field or those whereby the first wall is a sidewall of concrete, glass or fencing, and the second wall is a surface of artificial grass, concrete or gravel.

By the deliberate arrangement of the sensor lines or sensor strips, mutually and relative to the walls, it is possible to determine with the measured data whether the ball was played correctly or incorrectly. The processing of the data may be completed with additional intelligence coming from the processing of the measurement data.

The strips can, but do not have to, be parallel to the nearby walls

Preferably, the first sensor line or sensor strip is provided at a first distance between for example 0 to 3 cm from the first wall. Analogously but possibly deviating in terms of distance, the second sensor line or sensor strip is preferably provided at a second distance between for example 0 to 3 cm from the second wall.

In a specific embodiment at least two sensors are provided at every corner of the playing field for monitoring a first and a second wall of a sideline or a baseline of the playing field. In another embodiment the at least two sensors are arranged at two diagonally opposite corners of the playing field, whereby on every corner a sensor unit with the necessary sensors is provided which monitor the sideline and baseline bordering the relevant corner of the playing field.

In another specific embodiment the sidewalls of the playing field can be provided with additional detection means for detecting an "out-of-court play" whereby a player may leave the regular playing field to play back the ball.

This is possible by providing one or more extra sensor lines or sensor strips along the sidewalls or in front of the door opening, for example, which are mounted at a certain height, for example between 20 and 120 centimetres, whereby the processing unit can determine whether a player leaves the field.

The processing unit can also emit a signal which indicates that a player has left the playing field and it concerns an "out-of-court play" situation.

In a special embodiment the playing field is a padel court and the device can detect a "Bola Huevo" situation, whereby the first wall is a vertical sidewall or backwall and the second wall the ground.

The device can be provided in padel or squash playing fields, for example.

With the intention of better showing the characteristics of the invention, hereinafter, by way of an example without any limiting nature, preferred embodiments are described of a device according to the invention, with reference to the accompanying drawings, wherein: figure 1 shows a padel court; figure 2 shows how it is determined whether the ball first hit the wall or the ground; figures 3-7 schematically show a "Bola Huevo" situation shown according to the different phases of an incoming ball; figure 8 schematically shows a preferred embodiment of a device according to the invention for a padel court; figure 9 shows another embodiment of a device according to the invention; figure 10 shows an alternative preferred embodiment of a device according to the invention.

Figure 1 shows a padel court as described in the introduction. Figure 2 shows how in practice it is determined whether the ball first hit the wall or the ground.

Figures 3-7 schematically show a "Bola Huevo" situation according to the different phases of an incoming ball. Figure 3A shows a "Bola Huevo" situation whereby a ball 2 is hit deep to the furthest section of the court and will bounce here, for example on a sideline or a baseline in the corner (intersecting line) 10 between the glass wall 3 and the ground 4. An embodiment using sensor lines is shown here by way of simplest form of presentation. However, this example can also be worked out with sensor strips or fields, such embodiment being shown in figure 10.

As also shown in more detail in figure 3B, the intersecting line 10 between the vertical wall 3 and the ground 4 is provided with a first sensor line 8 and a second sensor line 9 whereby the first distance dl between the first sensor line 8 and glass wall 3 is maximum 3 cm and the second distance d2 between the second sensor line 8 and the ground 4 is maximum 3 cm.

The smallest distance d3 between the two sensor lines 8,9 is not bigger than 150% of the diameter of the ball, preferably not bigger than the diameter of the ball. These limitations also determine the height of the first sensor line 8 relative to the ground and the distance from the second sensor line 9 relative to the vertical wall.

The distance determinations dl, d2 and d3 are unambiguous for detecting whether a ball is played validly or not on the intersecting lines 10 (or baselines/sidelines) of the field.

In this example, both sensor lines 8,9 are provided parallel to the intersecting line 10 between the vertical wall 3 and the ground 4, assuming that the baselines/sidelines which determine the playing field, and more specifically the ball being in/out, are parallel to said intersecting line 10. In a first situation, as shown in figure 4, the ball 2 first hits the ground 4. The sensor line 9 is interrupted such that the second sensor 7 generates a first detection signal. Subsequently the ball 2 bounces further to the vertical wall 3, as shown in figure 5. The sensor line 8 is now interrupted such that the first sensor 6 generates a second detection signal. Subsequently the ball 2 rebounds into the court. Based on the first and second detection signal of the sensors, the processing unit determines a sequence in which the ball hit the walls. In this case a positive output signal is generated by the processing unit. This can, for example, result in a green LED lamp lighting up on the level of the net. This is a valid ball and play can simply continue. The green LED shows that the processing unit evaluated a "Bola Huevo" situation. In another option no output signal follows after a valid ball and play can simply continue. In a second situation, as shown in figure 6, the ball 2 first hits the glass wall. The sensor line 8 is interrupted such that the first sensor 6 generates a first detection signal. Subsequently the ball 2 bounces further to the ground 4 as shown in figure 7. The sensor line 9 is now interrupted such that the second sensor 7 generates a second detection signal. Subsequently the ball 2 bounces back into the court. In this case the processing unit will generate a negative output signal. In this case a red LED indicator, for example, will light up on the net post or another location which is clearly visible to every player. This is an invalid ball.

Figure 8 schematically shows a preferred embodiment of a device according to the invention for a padel court.

In every corner of the padel court two sensors 6, 7 are arranged here, one for the sensor line 8 at a first distance dl from the glass wall 3 and one for the sensor line 9 at a second distance d2 above the ground 4. The two sensors 6, 7 provide two sensor lines parallel to a baseline or a sideline. In this way the court is fully delimited with sensor lines for detecting "Bola Huevo" situations.

Both sensors 6, 7 can be incorporated in one unit if relevant. Thus, four such units are needed for a padel court.

Other arrangements are possible whereby only one unit is used per sensor line whereby it is transmitted by means of reflection to the relevant baselines and sidelines.

In yet another embodiment, a third sensor line can be added at approximately lm from the ground. This is because during the game it is permitted to retrieve a ball outside the cage, this is the so-called "out-of-court play" situation. In this case the software is set such that upon interrupting said third line no "invalid" signals are generated. Figure 9 shows another embodiment of a device according to the invention whereby the first and second sensor line 8, 9 are replaced by a first and second sensor strip 11, 12. The first sensor strip 11 is provided at a first distance dl from the first wall or glass wall 3, the second sensor strip 12 is provided at a second distance from the second wall or ground 4. In this example the sensor strips are provided parallel to the walls.

The embodiment shown in figure 10 shows a device according to the invention whereby the first sensor 6 is a pressure sensor to form a sensor strip 11 and whereby the second sensor 7 is an optical sensor to form a sensor line 9.

The pressure sensor is based on a pressure sensitive conductive plate which is mounted on the first wall 3 as it were.

The distance dl between the first wall 3 and the first sensor 6 is equal to zero hereby. The distance d2 between the second wall 4 and the second sensor 7 is between 0 and 3 centimetres, in this case 2 centimetres.

It is understood that the different types of sensors can all be used in one and the same device.

Alternatively, the present invention can also relate to a device for determining the sequence in which a ball hits a first wall and a second wall, similar to the device as specified in the claims, but whereby the sensors detect vibrations and are provided against the relevant walls or are connected thereto, and whereby the processing unit contains software to distinguish between vibrations of a ball with the wall near the corner and other vibrations, all this to enable the device to be able to determine the sequence of the contacts with the walls near the corner.

The present invention is by no means limited to the embodiments described as an example and shown in the drawings, but a device according to the invention as defined by the claims can be realised according to different variants without departing from the scope of the invention.