DE2410174A1 - PROCEDURE AND EQUIPMENT FOR DETERMINING THE DIRECTION AND SIZE OF THE SPIN OF PLAYING, IN PARTICULAR GOLF LINES - Google Patents

Description

Method and device for determining direction and 9 A 1 Π 1 7 A Size of the twist of game balls, especially golf balls.

The invention relates to methods and devices for determining the direction and size of the twist of game, in particular golf balls, preferably for practice the granting of a golf ball twist predetermined according to direction and size in golf game and practice halls like them already predicted by US Pat. No. 3,559,996 and have become known.

In many ball games, the game ball is modeled on the generation of the so-called spin when playing billiards or balls given a twist due to the special design and the type of playing or teeing off, whose job it is to trace the trajectory or trajectory of the ball that has been hit or hit by the spin or to be influenced by the twist in a predetermined manner, in particular for the purpose of producing a curvature the career or trajectory, the achievable variations of the latter enliven the game and make it interesting, also ^ should appeal to the skill of the player or players. It is well known that the Spin, in the fact that the playing stick used to play the billiard ball, called cue in billiards, at the time the impact of the billiard ball hits the latter in a direction that is not through theirs Center goes, but rather lies to the side of the same. The resulting, enclosing the center of the sphere The couple of forces is the cause of the twisting of the billiard ball, which causes the lateral, touches highly elastic band, whereupon it comes to the processing of the processes that characterize a game of billiards

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are. In a similar way, the golfer gives the golf ball by means of the golf club by "leaning" Impact a twisting movement that leads to the trajectory of the golf ball either, in relation to the golfer, assumes a curvature directed to the right or to the left and open towards the player. As technical terms have The technical terms of the "hook" introduced into the game of golf when the golf ball is warped to the left should, while a "slice" is used in the case of a warpage directed to the right. In addition to the physical Mastery of the golf shot, especially a peculiar, mainly spiraling rotation of the golfer around his body axis, it is a special one Concern of golf training, the prospective To give golfers a feel for the spin to be given to the golf ball. So far essentially was trained on open-air golf courses, was the training of the budding golfer burden imposed except by the tee-off itself, with leg work, seeking out, retrieving and, if not, any Golf boy, called Caddy, was on hand to bring it back of the golf ball with the relevant expansions of the distances between the to be played Holes quite considerable, so that it will be due to the fact that the proposal is to be realized closed golf arcades, renouncing the remarkable advantages of the outdoor GoIf game.

It is based on a finding leading to the present invention that such golf arcades are now being used for the first time open up the possibility of determining the direction and size of the twist that occurs during the exercise to be able to, so that the golfer is only put in a state of being made when using the golf club Defects both qualitatively and quantitatively determined-

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and to correct them in the course of the training, as the latter is only systematic and ultimately successful becomes possible if the type and size of the error are known, in particular errors that are due to physical and / or psychological predispositions are repeated over and over again. Assuming the presence of devices which make it possible to objectively reproduce errors made in the generation of swirl on the basis of measurements Determining type and size bring players into this the ability to see the need for correction oneself and to attempt to correct them in the event of further blows to avoid or at least to reduce.

This characterizes the narrower technical problem, based on the present invention from the knowledge presented.

The proposed solution to the problem is characterized by a method for determining direction and the size of the twist of game balls, in particular golf balls, preferably for practicing the issue a direction and size predetermined twist in golf arcades, according to the invention in that the Trajectories of a ball passed to a solid surface and thrown back by it afterwards with the solid surface formed entry and exit angles are scanned, the measured or calculated angles are compared with one another and the result of the comparison is converted into a signal about it.

Since there is no reason to make the training even more difficult by the fact that the solid surface is curved or is formed curved in various ways, rather it appears correct, from the nearest one The possibility of a completely flat design of the solid surface facing the golfer is based on the

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Optical reflection laws that can be transferred to the mechanical conditions under consideration are assumed that the trajectory of a golf ball passed to such a solid surface, which is assumed to be ideally designed, leads to the creation of an angle of incidence that must correspond to an equally large angle of reflection if the golf ball should not have any twist. The situation is different if the ball has been given a spin by means of the racket or in some other way, whereby two possibilities must be distinguished, namely a clockwise spin and counterclockwise spin. In the first case, the impact of a clockwise rotating golf ball on a solid surface opposite the player leads to a delay in the revolving movement as a result of the friction that occurs, which means that when the ball rebounds from the solid surface, the result must be a reduction in the projection angle compared to a projection angle that is realized would have been if the golf ball had not had a twist. The reverse is the case when the spin of the ball runs counter-clockwise; Then, as a result of the acceleration with which a rotating golf ball covers the lying elements following the point in time, -infinitesimally viewed, compared to a non-rotating ball, until the impact compression is converted into rebound work, the failure angle must be increased compared to the failure angle lead, which arises if the golf ball would not have made a revolving movement.

Since the possibility must be expected that the completely inexperienced golfer in particular will not yet is able to play the solid surface with the golf ball so that one of the golfer's stand with the Line connecting the point of impact perpendicular or at least

runs approximately perpendicular to the plane of the solid surface, 409838/0754

The proposed method i-iic Lee 'ibv.'lung can be carried out that the trajectories scanned according to the Mn and emergence angles formed with the solid surface are compared with corresponding angular values of a flight path, the emergence angle of which is compared with the angle of incidence of the scanned trajectory of the bailee played on the solid surface - agrees, and that the result of this comparison is converted into a signal about it. This requires the introduction of a measured value in the angle comparison, which changes in the event of major changes in the respective position of the golfer when teeing off, based on the location of the scanning or on flight point of the solid surface towards and away from it directed ball movement, with these changes also changes. However, the method specified at the beginning is already completely sufficient in the context of training work to give the golfer to be trained a sufficient feeling for the measures that lead to the occurrence of a twist of the golf ball predetermined according to direction and size lead, while in the training of golfers who are aiming for championships, for example, it can be useful to precisely record the conditions that occur in particular when the angles of incidence are extremely acute as a result of the very large distances of the point of impact from the golfer's standing position.

Devices for carrying out the proposed method can be designed in the most varied of ways. They are preferably characterized by the arrangement of a distance from the playing point for the game ball in connection with devices provided between the latter and the playing points for determining a first location at which a ball passed to the wall passes the device and for determining a second location , on which the same ball thrown back from the wall gives you. Device happened again, as well as in connection with a Gerrit to compare the two locations as well as to display the direction and size of the twist that had led to the second location of the ball passage. The handling is purposeful ^: 3ig the-already mentioned, level, play-places trains-

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applied the boundary surface without any other training opportunities excluded are. It is sufficient for the wall to be fixed, possibly movable Form screen wall, with the of the ^ vancLunr; properties to be fulfilled in the sense of Invention are to be regarded as existing if the V / and are under the arising at the time of meeting Impact load is not noticeably deformed and a ball hitting the wall without twist is so is reflected that the angle of reflection is either equal to the angle of incidence or substantially the same is the angle of incidence.

The devices for determining the locations of the ball passage can also have a wide variety of designs appear. They are characterized 'preferably by the fact that they are based on force fields and / or their changes responsive sensors are formed. The main force fields that come into consideration are those caused by electromagnetic vibrations, including, for example, visible light. In the last-mentioned case, Las means that at least one row of sensors designed as light cells is in Form connection with light sources at least one light barrier, so that such a light barrier penetrating ball, located between the light source and a certain sensor, the light emission

and/
The light source / cramt temporarily blocks the influence of the latter on the light cell of the sensor, so that the light cell exposed to the influence of the light change and thus appealing shows the passage of the ball and thus its location according to its local arrangement. Since this is the case when determining the first position at which a ball passed through the wall passes the light barrier, and since the process is repeated with modified values,

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when the thrown back EaIl the light barrier Assent to the second quay j), all that is required is an arrangement a computing device into which values corresponding to the two locations are entered, urn in connection with the given distance between, the wall forming the solid surface and the light barrier calculate the entry and exit angles and to be able to state numerically when it comes down to it. This is part of the training of a golfer is generally not the case, the golfer and possibly his instructors should generally only be informed about whether the golf ball by means of the golf club the direction of rotation and the torque have been issued that lead to the occurrence of the twist according to direction and size, which the golfer was given as a practice task or which he had set himself. For the reasons mentioned, one device is sufficient to compare the locations and to display the direction and size of the spin that had led to the second position of the ball passage. The elimination of the computing device thus enables the device to be designed for performing the method on determination of the direction and size of the spin of the game, especially the golf ball, which is through a majority of resistor and switch arrangements each under the influence of a sensor in connection with a power source and with a design of the device, identifies that for Display of direction and size of the twist leads a sensor passing from the wall thrown ball when it hit the latter. One forms the resistor and switch devices for this purpose in the manner of a flow divider, the devices in question can with a relatively minor effort

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technical means are implemented, whereby it is expedient to provide memory for the two local positions corresponding voltage values, again a device for comparing the latter and for specifying the result of the comparison is available.

It is in the essence of the invention that the reference to visible light controlled by the game or golf ball in no way exhaustively illustrates the possibilities under consideration. If it is also possible to use suitable shields to create light strands that serve to carry out the process so that the golfer is neither blinded nor disturbed by the light sources used to generate the light barrier, another option to be considered would be invisible ones to control electromagnetic vibrations by the trajectory and thus the passage locations to be scanned game ball, in particular golf ball, in such a way that the required information about the direction and size of the twist is displayed, which the scanned ball had when it hit the solid surface and which led to that the second location arose due to the first twist and the twist inherent in the & m ball. Force fields within the meaning of the invention s ^J "are accordingly also by swelling, the light lying for generating beyond the visibility limits, for instance by infrared or infrared region, polarized - ^ ient or caused by electromagnetic vibrations that only by appealing to them, electrical appliances are detectable.

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In the drawing, an example embodiment of the invention has been shown.

Fig. 1 illustrates schematically on the basis of one formed by a golf practice hall Playing field the basic conditions under consideration for different Angles of incidence and provided that the hall is completely flat Fixed surface, formed for example by a fixed, possibly movable Screen wall, is provided;

Fig. 2 again illustrates the field according to

Fig. 1 with a solid wall forming a solid surface, which also has a number only schematically indicated devices is upstream, the task of which is the determination a first location at which a ball passed through the wall passes the device, and the determination of a second one The location is where the same ball thrown back from the wall hits the device happened again;

Fig. 3 is also a schematic representation the scheme of a circuit with devices provided in this for determining the same locations, to compare these locations with corresponding electrical values and again for the visual display of the comparison result.

In FIG. 1, the golfer's standing area is denoted by 2. The fixed surface 4 lies opposite the standing area 2, so that a golf ball passed to the fixed surface 4 is thrown back from the fixed surface 4. If the golf ball has no spin, the angle of incidence corresponds to the angle of emergence, whereas this changes when the ball has been given a spin by means of the golf club. The projections of three different trajectories of the ball on the playing surface are shown with lines A, B and C. ¥ ith line A tracked, which corresponds to the projection of the trajectory of a golf ball, the tee riem no twist has been granted, so such a golf ball in the direction L · _f is reflected because then 409838/075 4

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that between the line Λ and the SohiiHtlirie of the solid surface Incidence angles of the included with the plane of the drawing Size according to corresponds to the angle of incidence between the line characterizing the fixed surface 4, accordingly also denoted by 4, and the line A ^ is included. That is true at least as a first approximation, assuming an ideal, flat solid surface and a design of a golf ball elastic properties are such that if a bell hit the solid surface without a twist and thrown back from it lead to the correspondence of the entry and exit angles; in any case, what has been said is largely true.

The situation is different if the golf ball used for allusion was given a spin when hitting it. If the golf ball runs in the clockwise direction, then, for the reasons given above, the failure angle is smaller than the interest angle, as follows from the fact that a clockwise golf ball, i.e. braked on the solid surface, takes a trajectory whose projection is on the playing surface corresponds to line A _7. If the spin of the golf ball is greater than was assumed when the line A ^ was drawn, the projection of a trajectory that then arises would then roughly correspond to the line A ^.

If, on the other hand, the twist given to the golf ball follows the direction counterclockwise, then the angle of failure becomes greater than the angle of incidence. This is on a golf ball whose incident trajectory in the projection corresponds to line A, by means of the dashed line Ap been illustrated.

What has been carried out for flight path A also applies analogously to flight paths B and C that differ from A.

In the illustration of Fig. 2 it has been assumed that between the now designated 6 tee point of the Goliballes equal to the position of the golfer and now with 9 designated Festf la before a number of devices for Determination of the locations where a

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the fixed surface 9 passed golf ball passed the row of devices for the first time and it happens again when it has been thrown back from the fixed surface 9 © The one between the tee point 6 and the fixed surface 9 in one A row of devices arranged parallel to the fixed surface are denoted by 10. Mutual spacing and arrangement the devices 10 depend on the particular training chosen from the same. In the embodiment according to FIG. 2 it is assumed that that thirty-two such devices are provided in a row next to each other and for example are designed as light cells, each on vertically directed light beams or their interruption respond, wherein light sources 12 are provided for generating the light beams. "Light cell" in this one The meaning used means a reference to light-sensitive and if light falls or if light is blocked, impulses issuing devices of the same type, e.g. also photodeclectors, photodiodes, phototransistors, Photo amplifier or any device that serves to perform the specified functions capable, whereby it does not matter that it is visible light. There are also rays of light invisible wavelengths, for example infrared rays, polarized light and all other electromagnetic waves Vibrations are considered if their presence or absence leads to the generation of impulses or even just Able to carry signals, including measured value displays.

The trajectory of a golf ball emitted from tee point 6 crosses the line of light cells 10 Light barrier formed at point 16 when the golf ball itself hits the fixed surface 9 at point 15. He blocks, as shown, the light beam associated with the light cell 10 located at point 16 Light source 12, so that it comes to the triggering of a signal that the first location, at which one one of one solid wall formed solid surface 9 leaked

0 9 8 3 8/0 7 5 U

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Golf ball the light barrier formed from the light cells 10 happened.

After hitting the fixed surface 9 at 15, the golf ball thrown back passes the one from the cells 10 formed light barrier for the second time, so that it is used to block more pus and other rays of light comes. The golf ball had no twist, so that the angle of incidence with the angle of incidence practically coincides, a light beam is interrupted, that of the light cell located at point 14 assigned. Conversely, signals other than those related to the location are triggered correspond, then the golf ball that reached the fixed surface 9 at 15 and was thrown back, a twist.

Ξε is a crisis fact that a right-handed golfer in the case of a right-hand delay of the golf ball this one running clockwise Had given twist, while the reverse was the case is when the golf ball has been warped to the left, so then the spin is counterclockwise is directed. Correspondingly, the line 17 indicates that the thrown back at the contact point 15 Golf ball was subjected to a "hook" stroke, with the location of the reflected ball through the point 13 is marked so that the light cell 10 located there allows the passage of the golf ball indicates. It corresponds to that the dashed lines 19 or 21, which in turn from the point of impact 15 assume that their origin can be traced back to "slice" hits on the golf ball. The ball passages are accordingly determined by points 11 and 8, respectively. The light cells located there speak accordingly. From this it is easy to judge whether and how many "hook" or "slice" hits the golf balls have had an impact.

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As has already been stated, the formation is one that leads to the realization of the B'estfläche S Wall not tied to the fact that the fixed surface 9 is completely flat. The "wall can also be designed so that the surface 9 is arbitrarily curved or areas on v / eist that in the ¥ angle to stand by each other. There is the further possibility, the wall or the solid surface in this way train that as a function of the angle of incidence certain failure angles occur, specifically in golf balls that have no twist, so that then the law of reflection mentioned at the beginning is no longer effective. You are also not bound to it that the tee points are always consistent, as indicated at 2 and 6; vice versa there is the possibility of aligning the fixed surfaces to certain teeing points and to be trained accordingly. Then it can be advantageous not just a row of light cells or to provide their function having devices, but it could, as in 110 of the Figure 2 indicated, a further row of measuring devices between the tee point 6 and the row of measuring devices 10 may be provided. Arrangements of this type come into consideration when attached to the devices additional requirements are made to display the location of the passage, for example may include scanning the trajectories according to the heights that occur in each case.

As the circuit diagram of FIG. 3 illustrates, an installation for carrying out the method designed according to the invention has a series of resistors R1 to R32 connected to a power source indicated by the battery 26, are connected in series, with a variable resistor RA is available. The resistors R1 to R32 are connected to a main line 28 via switches S1 to S32.

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The switches S1 to S32 are each assigned to the thirty-two light cells 10 of FIG. 2 and they are open with the exception of the case that light incident on one of the light cells is blocked. ^{In this case, relays c 7} pn <~> cier, not shown, which are known per se, close the switches. The arrangement shown and described is therefore essentially that of a current divider which is connected to the battery 26. Its Ii ¹ UnICtion consists in the fact that when the golf ball passes through the light beam, which had excited the light cell under consideration until the ball passed through and kept the associated switch closed, the interruption of the light beam acting on the light cell leads to the switch being closed mentioned relays become effective, in their place of course other, known, electrical or electronic hatreds can be realized.

"^ ZF-ichngte switch / The in the drawing with SA2, with the assigned relay is in the also shown open position of all switches S1 - S32 in the graphically illustrated, normal switched-on position. But if a golf ball passing the light barrier blocks one of the light sources 12 in Fig. 2 emitted light beam, the light cell previously excited by the light beam under consideration responds immediately to the interruption, so that a voltage occurs at the switching point 32 which is indicative of the incidence of one of the switches S1 to S32 or, if several light beams The voltage that arises at 32 reaches the capacitor C1, in which it is stored, via the switch SA2, which is in the sin switch position. The voltage that arises at 32 continues to act on the relay 30, and in such a way that it is necessary to switch the switch SA2 from the on to the Au switch position comes, which means that the variable ¥ ider-

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Standes RA comes into the circuit.

Since the golf ball thrown back from the fixed surface 9 passes the light barrier formed by the light cells 10 for the second time, the pulse is emitted by the / effie ^ wett'irif light cell 10, see above, depending on the interruption of the light beam for which the thrown golf ball is the cause that another of the switch series 31 to 332 is closed. This leads to a voltage occurring at the switching point 32, which voltage is now stored _{in the capacitor C 2 as a result of the switch SA2 being switched over in the meantime.} The variable resistance RA is set so that when a golf ball rebounds from the solid surface, which here had no twist, so that the angle of incidence is equal to the angle of incidence of the golf ball, the electrical voltages occurring at switching point 32 also completely or practically coincide leads to the fact that in the capacitors C ^ and C ₂ matching voltage values or, with the same meaning, the same storage charges occur. This means that the required setting of the variable resistance RA must be carried out in the sense of a calibration before the start of training. The comparison device 34 serves for this purpose, the pointer 40 of which is brought to the center position shown during calibration, which optically indicates that the device shown in FIG. 3 has reached the operational state.

If the training now begins with the aid of the device illustrated in FIGS. 2 and 3, it should be assumed in accordance with the illustration in FIG. 2 that a golf ball knocked off at 6 had reached the nest surface 9 in points. In this case, a light beam emanating from a light source is the previously assigned

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Light: 'ell ^ Ic so influenced, ca-3 the Lchalter £ "£ open who, blocked, · εο oa £ in the already shown,." Eise 6 he Ichalter C ^, - was closed-, ν: οΓΠ' . ί "at d ^c r in Fig device illustrated 9, the processes were set in Lsuf that led to that in the capacitor C ₁ ν: ie entering the charging, the at Übereinsti: ;;: Aung with an equal Auflacur. g ces L'ondcnsctcrs C- would lead to the

the kücli-'jrGll of a golf ballet; an-ez ^ i-t

h "t '; s, de?" Lei j .VL-itreifp-n iu Purihtc I ^ l: a Lr? Ll ΙοεξΓ ;. Ιλ? It is untrue about vüllijV that it is untrue that ' ^: he errtc Err. i: iin £: cbc: .ll to a'.,; eccrhclun ^ the cei der L-ivhunj; the establishment of the previous relationship ce, vrird c ? .vcn to assume that as a result of passage C-es golf ball through a lici: tstr £ .hl hincurch, r'rr i "o d-cr previously derrreßteir ter""'eisezu; :: appearance of a Lexun .: iiii Konäensctor C- leads ractiieden the v ^ ven der Laoun-- _ir;; hordcns-tor Z *, the rassele a Golfhc-.lles by the light barrier e.::._ezei^tv:ird, the ult swirl e. On the fixed surface 3 in Fi ₀ -. 2, the device 34 thus indicates, in accordance with the voltage and charge surpluses occurring in the capacitors, which occur increasingly larger with the amplifiers L ^ and /. A ₀ , that who 'Cc ν. ΐΐ ^ ζ ab c chi ? ■. £ had led to;., .jaftrctcn a Gclfballes, which at the meeting at the FestfIr'ehe- 9 a riot of smaller or larger sizes occurring with a fixed circulation meaningful speed esp ate. . According to the combined -iit ready Fig.2 "considered local layers 3 and 11 with the result of Slice - en occurring blows iVickprallrichtun ^ 21 and 19 suggests the pointer of Vergleichsgerätcc J4 in ö.zc the SLICIj - FCHL: igen vorbehaltenc a Ckslenfeld , v,. ührena the Uiugehehi ^ te is the case, ^'r the Crtslage of zuru.clrprallenden golf ball in Fassage the light barrier formed by the photo detector 10 by the funct 18 and the direction of GoIfcalles after the hen i-.irokv. rall are given by the line 1? with which the pointer 40 of the comparison device 5 ^l - sweeps the scale field on the right and labeled HCCI ".

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In contrast, pointer 40 plays on the center line on the Scale field on when the rebounding ball crosses the light barrier happened in point 14, there then only one repetition of the calibration strike would have been realized.

If in a device according to FIG. 3, the voltage ratios are chosen so that in Schaltounlit 30 a Tension from. 14 volts occurs, the ratios can be chosen so that when the Back and forth angles, i.e. when teeing off golf balls, which had led to the impact of the golf ball without 'twist on the fixed surface 9, the capacitors on the corresponding voltage of 16 volts are charged. If, on the other hand, there is a hook strike with the passage point and the rebound direction 17 before, the charging voltage of the capacitor C- amounts to 20.6 volts. That means that a voltage difference of 4.6 volts occurs in the comparison device, which the pointer 40 to be imported to the scale field corresponding to this voltage difference. "Will the voltage difference larger as a result of a higher twist, the pointer 40 points to further to the right Scale fields or scale lines if the scale is divided into scale lines. In the same V / alternatively, slice strokes are made by moving the pointer 40 on the left half of the scale of the device displayed.

From the description of the drawing it can be seen that an execution according to FIGS. 2 and 3 is not an execution further operation is required, if in each case practice balls or balls to demonstrate the skill of the golfer have been knocked off. The facility can still be supplemented to the effect that for Zrnahme of altitudes of the Game or golf ball the devices for determining the passage positions not in horizontal, but in vertical, or arranged in both horizontal and vertical positions. -However, it is sufficient for determination from the direction and magnitude of the twist an execution according to Figures 2 and 3 of the drawing completely,

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Supplementary arrangements are only required if measurements are carried out in a wide variety of directions If necessary, computing devices should be provided for evaluating the Hess results.

As far as the above-mentioned modification of the method comes into consideration, the kesswert to be introduced into the angle comparison is obtained by selecting among other devices that are used to determine the location of passage points so that they correspond to the strongly changed stand of the golfer on the playing field so that a line containing the center of the stand and directed towards the fixed surface runs perpendicular to the plane of the fixed surface. Then the location of the selected device provides the Hesswert, because the connecting lines all devices that. are equidistant from the selected device, connected to the intersection of the line going through the selected device and perpendicular to the fixed surface, include angles which coincide with one another and therefore correspond to the same entry and exit angles. The same result can be achieved if the kull line of the comparison device is automatically changed depending on the selection of the standing and teeing-off place so that the devices are connected to the selected device in one direction, which characterize slice strokes ε.ΐε such, and that in the opposite direction the devices are connected to the selected device which indicate the hooks.

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Claims (1)

/ J Claims Procedure for determining direction and size the twist of game balls, especially golf balls, preferably for practicing the issue a golf ball twist predetermined according to direction and size in golf arcades, characterized in that the trajectories of a ball passed to a solid surface and thrown back by it scanned according to the entry and exit angles formed with the solid surface, these angles with one another are compared and the result of the comparison is converted into a signal about it will. Method according to claim 1, characterized in that that the trajectories scanned according to the angles of incidence and emergence formed with the solid surface with corresponding ones ¥ the vortex values of a trajectory are compared, the angle of incidence with the angle of incidence of the scanned trajectory of the fed to the Feεtflache Everything agrees and that the result of this comparison is converted into a signal about this is converted. Device for carrying out the method according to one of claims 1-2, characterized by the arrangement of a distance from the play point for the game ball having a wall in connection with between the latter and the play points provided devices for determining a first location, one of which is played to the ¥ andung Ball passes the device, and to determine a second location lar - e, to which the same, from the ", vainung zu-409838/0754 thrown ball passed the device again, as well as in connection with further a device for comparing both locations and for displaying direction and size the twist that led to the second location of the ball passage. 4. Device according to claim 3, characterized in that the wall has a flat, playback points facing boundary surface. 5. Device according to one of claims 3-4, characterized in that that the wall is designed as a fixed, but possibly movable screen wall is. 6. Device according to one of claims 3-5, characterized in that that a device for determining a ball passage location as on Kraftfeider and / or the changes of which responding sensor is formed. 7. Device according to claim 6, characterized in that at least a number of sensors designed as light cells in connection with light sources form at least one light barrier. S. Device according to one of claims 3 - 7 »characterized by a Honesty in each case under the influence of one sensor each resistance and switch arrangements in connection with a power source and with a training of the facility 409833/0754 ft which leads to the display of the direction and size of the twist that a sensor passes, ball that was thrown back from the wall when it hit the latter. 9. Device according to claim 8, characterized marked that the resistance and switch devices designed in the manner of a current divider. 10. Device according to one of claims 8-9, characterized in that that they memory for the two locations corresponding voltage four te and a Gera to compare the latter so; ie to display the result of the comparison on v / eist. at For this 2 sheets of drawing ^ 409838/0754