The playing of ball sports generally requires a certain amount of dexterity. In order to acquire this dexterity beginners must practise. To accelerate this practice it is desirable to practise different aspects of the ball game separately. Particularly in the case of tennis, practice of strokes takes place by for instance a trainer throwing balls, or this takes place with a so- called ball cannon. Both methods have the drawback that the ball possesses a certain speed at the moment the stroke must be practised. This makes the exercise rela- tively complex for beginners. When the balls are thrown there will necessarily be variation in the position at which the balls have to be hit. Finally, this requires much coaching time of the trainer.

The present invention has for its object to provide devices and a method for effective training of a begin- ning ball sport player, in particular a tennis player.

The invention provides for this purpose a device for suspending a ball, such as for instance a tennis ball, comprising: - a driven fan for generating an air flow, - an air duct which is connected to the fan and which is connected on one side to the fan and provided on the other side with an outlet opening, wherein the inside of the air duct is provided with an air flow guide element placed in the air duct.

Using this device it is possible to place a ball in a stable suspended position so that a beginning ball sport player can practise a stroke on a stationary ball.

In addition, the ball is readily accessible since it is situated freely in space. It is very advantageous that correct striking of a ball can be practised first without complicating factors such as for instance ball speed and timing.

In preference the wall parts of the air flow guide element lie substantially perpendicular to a cross-sec- tion through the air duct. The air flow guide element can herein comprise a plurality of parallel plate-like ele- ments and/or a plurality of parallel tubular elements.

For horizontal stability of a ball in the air flow it is important that the air flow be narrow and sharply de- fined. This can be realized by choosing a small diameter for the tube. The air must further be as homogenous as possible when leaving the tube and have no speed in a direction other than the flow direction. The air flow guide elements contribute hereto.

In another preferred embodiment the air duct is curved close to the outlet opening and the air flow guide element extends at least over a part of the curve of the air duct. In this manner a device can be constructed whereof the outlet opening is situated a short distance above the ground. This has the important advantage that it is possible to suspend the ball a short distance from the ground whereby it is also possible to practise with low balls, which is desirable for instance in tennis. The device preferably comprises a reservoir for containing the supply of balls and a control mechanism for adjusting the speed at which balls are carried from the reservoir into the air flow. Due to these measures balls can be supplied automatically, whereby a ball sport player can practise a large number of balls in succession without paying attention to the device. It will be apparent that in addition to the control mechanism for supplying the balls, an adjusting mechanism can also be present for

adjusting the air flow which may or may not be provided with sensors for causing the adjustment of the air flow to depend on whether or not there is a ball present in the air flow and/or on the height of the ball in an air flow.

The fan is preferably a centrifugal fan driven by an AC motor or a brushless DC motor. These measures ensure that the device has a sufficiently long lifespan.

The invention also provides a device for ejecting a ball, such as for instance a tennis ball, comprising: - two throwing wheels placed in the same plane and driven rotatably in mutually opposing directions, wherein the mutual distance between the throwing wheels is smaller than the diameter of a ball for ejecting, and - supply means for supplying between the wheels a ball for ejecting parallel to the rotation direction of the throwing wheels at the position where the mutual distance between the throwing wheels is smallest.

When a ball sport player has acquired some profi- ciency using a ball which is stationary in the air flow, the training can be made more difficult by providing a ball which moves relatively gently. When the throwing means and the supply means are mounted on a carrier which is rotatable and fixable in a frame for the purpose of varying the ejection direction, it is possible to supply to a ball sport player balls moving in horizontal direc- tion as well as vertically moving balls. For this latter it is necessary to envisage for instance practising of service, in which case the device must eject a ball at an angle of about 90" relative to the ground surface. This device clearly differs from a so-called ball cannon wherein balls are fired at a ball sport player at very great speed from a relatively large distance. This is useful for more advanced ball sport players but for less experienced ball sport players the device for ejecting a ball according to the invention is more suitable.

A particular preferred embodiment according to the invention combines that described in the foregoing in the

devices for suspending a ball and ejecting a ball. This combination device is an all-round training aid for beginning ball sport players and combines the advantages of the above described devices.

Another preferred embodiment is characterized as described in claim 12. This device has the advantage that only one ball reservoir is required from which the balls can be discharged out of one of the two openings as desired without a very complex control mechanism being required for this purpose. This transport can for in- stance take place in that the balls roll under the influ- ence of the force of gravity.

When beginning ball sport players practise, many balls will be struck as described above. An irritating consequence thereof is that after practising for a time a large quantity of balls scattered over the entire prac- tice court will have to be collected. In order to mecha- nize this collection the invention provides a device comprising a profile edge for placing round at least a part of the court which has an upward sloping surface as seen from the court and a gutter located behind the incline, wherein transporting means are arranged in the gutter for transporting the balls to a central location.

The transporting means are herein preferably formed by a rotatable rope, a part of which is located in the gutter such that balls situated in the gutter make con- tact with the rope part and are carried along. Balls which have been struck will roll up against the incline such that they land in the gutter lying behind. The transporting means situated in the gutter, for instance the rotatable rope, which can be embodied very inexpen- sively, subsequently transport the balls to a central location.

In order to prevent balls which have been struck hard and high from passing over the gutter without stop- ping therein or from for instance flying thereover, a collecting net connects in a preferred embodiment onto the side of the profile edge remote from the court.

Finally, it is recommended that the balls transport- ed to a central collection point by the collecting device be placed into a ball reservoir of a ball machine using a ball transporter so that practice can continue without any attention having to be paid to collecting and/or placing into the ball apparatus of the already used balls. These are now carried back mechanically into the ball dispenser by the collecting device.

Finally, the invention provides a method for sus- pending a ball, such as for instance a tennis ball, in an air flow, wherein the ball is carried into the air flow with a rotating movement. The stability of a ball situat- ed in the air flow depends partly on the surface quality of the ball. This is particularly the case with balls having an irregular surface. By carrying the balls into the air flow with a rotating movement the stability of the balls in the air flow is considerably improved.

The present invention will be further elucidated with reference to the non-limitative embodiments shown in the following figures. Herein: Fig. 1 shows a partly cut-away perspective view of a combination device according to the invention which shows in particular the device for suspending balls in the air flow, Fig. 2 shows a perspective view of the device of fig. 1 which shows in particular the device for ejecting balls, Fig. 3 shows a top view of a disc assembly as incor- porated in the ball reservoir of the combined device as shown in fig. 1 and 2, Fig. 4 is a top view of a disc assembly as shown in fig. 3 in a different position, Fig. 5 is a side view of a disc assembly as shown in fig. 3 and 4, Fig. 6 shows a perspective view of a practice court with collecting devices according to the invention.

Fig. 1 shows a tennis ball dispenser 1 with which a tennis ball 2 can be placed in a stable state of suspen-

sion by means of an air flow, here shown using an arrow P1, which provides a good practice option for tennis beginners. Balls can moreover be ejected with the tennis ball dispenser 1, as will be elucidated with reference to fig. 2. The tennis ball dispenser 1 comprises a housing 3, which is cut-away in this figure, having a protruding elongate part 4. Close to the end of the elongate part 4 is situated an outlet opening 5 from which exits the air flow for holding tennis ball 2 in the air. The elongate part 4 is designed such that it does not interfere with the striking of tennis ball 2 with a tennis racket.

An air duct 6 connects onto outlet opening 5. The outer end of air duct 6 is curved upward close to the outlet opening and in the air duct an air flow guide element in the form of parallel plate-like elements 7 is situated in this curve. The parallel plate-like elements 7 provide an air flow in which a tennis ball 2 will float in relatively stable manner. On the side of air duct 6 remote from outlet opening 5 connects a centrifugal fan 8 for generating the air flow P2 in air duct 6. Centrifugal fan 8 is driven via a belt 9 by an AC motor 10. In the upper part of housing 3 of tennis ball dispenser 1 is arranged a reservoir 11 for tennis balls. The tennis balls situated in reservoir 11 can be distributed one by one into a ball guide 13 by means of a disc assembly 12.

The operation of disc assembly 12 will be elucidated below with reference to fig. 3-5. A ball deposited by disc assembly 12 into ball guide 13 will roll in a chute 14 arranged in the upper part of the elongate part 4 of housing 3. Chute 14 inclines downward in the direction of outlet opening 5, toward which the ball situated in chute 14 will thus roll. Having arrived there, the ball will be carried out of outlet opening 5 by the air flow into the position as shown in the figure.

Situated on the rear side of tennis ball dispenser 1 is a ball throwing mechanism 15 which will be further elucidated in the following figure.

The throwing mechanism 15 is further elucidated in fig. 2. Two throwing wheels 16 are driven by a drive 17 such that the left throwing wheel 16 rotates counter- clockwise and the right throwing disc 16 rotates clock- wise. The mutual distance between throwing wheels 16 is smaller than the diameter of the ball 2. A tennis ball 2 supplied from ball reservoir 11 through disc assembly 12 is carried by a guide 18 to an actuator 19 which may for instance consist of an electromagnet. Actuator 19 presses tennis ball 2 between the throwing wheels 16. Throwing wheels 16 will herein slightly compress the tennis ball 2. The tennis ball will be displaced upward by throwing wheels 16 to a position where the mutual distance between throwing wheels 16 is so large that they do not compress tennis ball 2. When the rotation speed of throwing wheels 16 is sufficiently large the tennis ball 2 will be eject- ed as according to the arrow P3. Throwing wheels 16, drive 17 and actuator 19 are mounted on a plate 20 which is rotatable relative to housing 3. Fixed to plate 20 in this figure is a protective edge 21 in which is arranged an ejection opening 22. By rotating plate 20 as according to arrow P4 the ejection direction can be varied. Ejec- tion of a tennis ball as according to arrow P5 or P6 is hereby also possible. The guide 18 can be fixed in sta- tionary position when guide 18 supplies balls to the rotation point of rotatable plate 20. For this purpose the rotatable plate 20 is mounted using a hollow shaft 23, through which hollow shaft 23 the guide 18 is placed.

Fig. 3-5 show the disc assembly 12 in the underside of the ball reservoir as shown in fig. 1 and 2. An upper disc 24 is provided with recesses 26. When upper disc 24 is rotated round a shaft 27, balls situated in reservoir 11 will be carried along with upper disc 24 since balls will be situated in the openings 26. Situated beneath upper disc 24 is a lower disc 25, as shown clearly in fig. 5. In lower disc 25 a recess 28 is arranged at one position which is larger than the diameter of ball 2.

This recess 28 in lower disc 25 is shown in fig. 3 and 4

by means of a broken line. The lower disc 25 is also rotatable around rotation shaft 27. Depending on the position of the recess 28 in lower disc 25, a passage is left clear to the guide 18 which supplies balls to throw- ing mechanism 15 or an opening is left clear to the ball guide 13 for supplying the balls to the chute 14 which leads to outlet opening 5.

A drive 29 drives the upper disc 24. Upper disc 24 and lower disc 25 are placed against each other under bias such that when upper disc 24 rotates the lower disc 25 will be carried along. Lower disc 25 is however pro- vided with two stops 30,31 whereby lower disc 25 will be stopped when it runs up against a ratchet 32 which is mounted in stationary position on the tennis ball dis- penser 1. Depending on the rotation direction of upper disc 24, stop 30 or stop 31 will after a time impinge upon ratchet 32. In fig. 3 the upper disc 24 rotates clockwise whereby recess 28 leaves clear the guide 18 to throwing mechanism 15. In fig. 4 the upper disc 24 ro- tates counter-clockwise and stop 31 impinges upon ratchet 32, whereby the recess 28 in lower disc 25 leaves clear a passage to the ball guide 13 for suspension of a ball.

Finally, fig. 6 shows a tennis court 33 on which a tennis ball dispenser 1 is placed with which a player 34 is practising. Placed around tennis court 33 is a profile edge 35 whereof the side facing the tennis court 33 has a sloping surface. On the side of profile edge 35 remote from tennis court 33 is situated a gutter-like part 36.

Connecting onto the profile edge 35 are collecting nets 37 with which balls which have been struck hard are guided to the gutter 36 in profile edge 35. Arranged in profile edge 35 are transporting means for balls prefera- bly consisting of an endless rope. These transporting means provide transport of the collected balls to a central point 38, from which they are fed back to tennis ball dispenser 1 with a ball transporter 39. The tennis ball transporter 39 can be formed for instance by an air pump or a chain provided with scoops.