EP2257346B1 - Device and method for monitoring the hitting accuracy and the swing movement of a golf club - Google Patents

Description

The invention relates to a device and a method for controlling the accuracy with which a golf club is guided in the swing, according to the preambles of the appended claims 1 and 9.

Especially when putting, it is crucial that the putter used for this purpose is guided very precisely, so that it hits the golf ball with the ideal point of the face, the so-called sweet spot, taking into account the center of gravity. The situation is similar when chipping and pitching.

Normally, only the result of a large number of putts reveals whether a golfer masters the putt techniques and regularly hits the sweet spot. Occasionally, a camera is used to help optimize the movement, but shooting and evaluating the movies are time consuming and expensive, so they can only be considered as a temporary measure. It is also possible to apply a pressure-discoloring foil to the face of the putter before each putt and then to evaluate the sequence of the slides. This procedure is also too cumbersome to be practiced over a longer period of time.

From the US-A4898389 It is known to releasably attach to the head of a golf club a row or array of transducers with displays, each indicating whether they hit the ball.

The WO 2005/094953 A2 describes a golf club in which the location where the golf ball meets the club face is determined by sensors for electromagnetic or ultrasonic waves reflected from the ball.

From the JP H08-34730 B2 is a device for controlling the accuracy is known, with a golf club is guided in the swing and hits the club face of his club head a golf ball. This device comprises a plate-shaped sensor, which consists of two electrically conductive layers, which are spaced by an intermediate layer consisting of a flexible, under pressure conductive material. At the moment of a relatively large impact of a golf ball on the striking surface, the two conductive layers are electrically connected in the area of the impact by the intermediate layer, but never directly in contact with each other.

Finally, by the company Alan Electronics GmbH, 63303 Dreieich with the Internet address www.dixxgolf.de under the name "DiXX Digital Instruction Putter" a golf club distributed, which offers the possibility, on the back of the club head either a housing, the acceleration sensors, a Includes metering and evaluation electronics and a flat panel display, or a weight that is as heavy as this unit to attach interchangeably. Although the acceleration sensors are capable of detecting several parameters of the golf club movement during a swing, u. a. also the location of the impact point on one side or the other of the sweet spot. A precise determination of that point of the club face with which the ball was hit, however, is not possible with such a measuring method.

The invention is therefore an object of the invention to provide a device of the type mentioned above, which can be attached to a conventional golf club without changing its properties significantly, no disturbing secondary activity during playing only for measuring purposes requires the impact of the golf ball and the Swinging movement of the club head more accurately than previously registered and the recorded and evaluated according to the program results in a form that they are always at hand.

The above object is achieved by a device according to the appended claim 1, and also by a method according to the appended claim. 9

The plate-shaped sensor is so light and thin that it is virtually imperceptible when a strike is made. As a result of the attachment to the golf club's face, not on its back, every point of impact is registered very precisely. The preferably attachable to the shaft of the golf club measurement and calculation circuit increases its weight only minimally, because they need only perform the necessary functions to control the measurement process and to determine the coordinates of the impact point and spark the measurement results, for example, to a cell phone or smartphone. There they can be stored and evaluated by means of suitable programs. A cell phone, smartphone or the like with a radio module is usually available anyway and is regularly taken to the golf course. Suitable programs for the evaluation of the measurement results can be made available on the Internet for downloading to the mobile phone or smartphone. Thus, it can be read immediately after a blow from the display of the phone, which point of the club hit the ball. The player can then try on the next stroke to correct any mistake in holding and leading the racket. In addition, at any time and on any occasion, such as during a train ride or in a restaurant, he may take the mobile phone and, with others, view alone or with other golfers the level of accuracy he has collected, evaluated and displayed in graphs, for example Compare and discuss players.

The rotation rate sensor provided according to the invention in addition to the plate-shaped sensor registers in cooperation with the electronic measuring and arithmetic circuit the direction of rotation, angular velocity, angular position and duration of the phases of the back and forward movements of the club head. The measurement results obtained can be used in such a way that only the plate-shaped sensor is activated when the readings of the rotation rate sensor are close to a hit against a golf ball in a certain frame and thereby the expiration of a normal back and Vorschwungbewegung the club head signal. The rotation rate sensor thus helps to avoid random strokes against other objects or pre-drills prior to a stroke being included in the statistical and graphical evaluation of the focused strokes. In addition, the rotation rate sensor in conjunction with programs for evaluating its measurement results, the ratio of the duration of the backswing to the duration of the advance to the impact against the ball, also from the angular positions of the golf club at the end of the return swing, at the impact on the Ball and at the end of the previous swing to gain important clues to mistakes in the leadership of the golf club during the swing movement. By multiplying the angular velocity by the radius of interest in each case, the speed of the club head when hitting the golf ball can also be determined. Finally, it can be determined and displayed in the interaction of the yaw rate sensor, also referred to as gyro, with the plate-shaped sensor that the putter has hit the golf ball with the club face, but at a position outside the plate-shaped sensor.

The plate-shaped sensor is constructed in the manner of a computer touchpad with a rectangular support plate with a first electrically conductive layer applied on its front side, which is connected along two opposite edge regions each with a printed conductor connected to a signal line, and one in front of the carrier plate arranged, flexible protective plate having a deposited on its back, the second electrically conductive layer, which is connected along two opposite edge regions in each case connected to a signal line, a printed conductor extending transversely to the interconnected with the first conductive layer interconnects, wherein the conductive layers are separated by elastic spacers, the restoring force is chosen so that it comes only temporarily when a blow to a golf ball at the point of impact to the contact between the conductive layers.

Such a touchpad is for example in the US Pat. No. 6,239,790 B1 to which reference is hereby made for the purpose of describing the operation of the above-identified sensor for the sake of simplicity. It should be noted, however, that a computer touchpad, for example, on a laptop, properly mounted insoluble in the case of the computer and only relatively light and slow touched with the finger. The sensor of the measuring device according to the invention on the other hand, it is much more mechanically stressed by the blows against a hard golf ball. In addition, different requirements apply to the sensor because, in contrast to a computer touchpad, it should be easily detachable from the supporting surface.

It has surprisingly been found that despite the higher compared to a touchpad, sudden loading when using the same materials, the solution of the problems arising from the other conditions does not exist in a thicker or stronger training of the sensor, but just the other way around in a reduction the plate thickness. While in a touchpad of the type mentioned the support plate normally has a thickness of about 1.6 mm, the support plate of the new sensor can be about half as thick, because it is supported over its entire surface on the clubface of the golf club, so that a larger Strength is not required.

At the same time, with the reduction of the thickness of the carrier plate, the advantage is achieved that it and with it the plate-shaped sensor becomes more flexible, so that when it is fastened with a double-sided adhesive film on the clubface of the golf club, it can be detached more easily.

Another difference between the sensor of the proposed measuring device and a computer touchpad is that the carrier plate of the Töuchpads is provided on its back or bottom with printed conductors and electronic components. In the case of the proposed sensor, by contrast, the sensor electronics are located in the housing, preferably mounted on the shaft of the golf club, of the measuring and calculating circuit. The thinner carrier plate and the displacement of the sensor electronics to the club shaft has the other advantageous consequence that the entire plate-shaped sensor only needs to have a thickness of about 1 to 2 mm and thus the clubface of the golf club is only minimally advanced.

The sensor of the new device is more exposed to changing temperature and humidity than a computer touchpad. Therefore, it is expedient that the protective plate in the edge region materially connected firmly and tightly connected to the carrier plate except for a ventilation opening, z. B. is glued. The ventilation opening can be covered with a waterproof, but gas-permeable film or by an overlap, such. As in a labyrinth seal, be sealed so that the sensor is at least dust and splash-proof to IP54.

Tests have shown that the sensory-active area of the sensor only needs to be about 45 to 65 mm wide, and for putter about 16 to 20 mm, for pitchers for pitching and chipping 20-30 mm high. The sensor may be mounted so that its center is coincident with the sweet spot, which is preferably in the center of the clubface.

In addition, it appears expedient that the signal lines between the sensor and the measuring and computing circuit have a separable connector. This allows the two units to be individually attached to the golf club and replaced. Preferably, one connector half is fixedly attached to the housing of the measuring or arithmetic circuit or fixed to the carrier plate, while the other half connector is located at the free end of a cable. For the attachment of this housing on the shaft of the golf club a variety of design variants are available. It may already be sufficient to friction fit the housing by means of at least fix a clamp or a strap on the shaft, with a rubber-like contact surface or liner is beneficial.

The device according to the invention can be used particularly advantageously when a golfer experiments with additional weights which are fastened in the hollow shaft of the golf club in order to find out with what additional weight and with which position of the weight in the shaft he achieves the best impact results.

Fig. 1

eine schematische Darstellung der Gesamtkonfiguration der vorgeschlagenen Vorrichtung;

Fig. 2

einen vereinfachten Querschnitt durch den plattenförmigen Sensor;

Fig. 3

ein Ersatzschaltbild des plattenförmigen Sensors;

Fig. 4

die wesentlichen Teile der am Schlägerschaft angebrachten Sensorelektronik;

Fig. 5

eine über der Zeit aufgetragene, durch den Drehratensensor ermittelte Kennlinie der Winkelgeschwindigkeit des Schlägerkopfes während des Puttens;

Fig. 6

einen vereinfachten Querschnitt durch das Gehäuse der Sensorelektronik und den Schlägerschaft an einer Befestigungsstelle;

An embodiment of the invention will be explained below with reference to the drawing. Show it:

Fig. 1

a schematic representation of the overall configuration of the proposed device;

Fig. 2

a simplified cross section through the plate-shaped sensor;

Fig. 3

an equivalent circuit diagram of the plate-shaped sensor;

Fig. 4

the essential parts of the sensor electronics mounted on the club shaft;

Fig. 5

a plotted against the time, determined by the rotation rate sensor characteristic of the angular velocity of the club head during the putting;

Fig. 6

a simplified cross section through the housing of the sensor electronics and the club shaft at an attachment point;

In Fig. 1 a golf club is shown, the club head with 10, 12 with shank and handle 14 are designated. On the striking surface 16 of the club head a sensor 18 explained in more detail below is fixed, whose active sensitive area is designated 20. In this case, the directions of the coordinates x, y and z used below are also entered. Their common starting point is in Sweet Spot 22 of the clubface 16.

The sensor 18 is connected via a plug connection 24 and to a cable 26 combined signal lines with a mounted in a protective housing 28, generally designated 30 sensor electronics with a measuring and arithmetic circuit, which is mounted by means of an easily detachable fastening mechanism 32 on the shaft 12 and a radio module 34, preferably Bluetooth, with a mobile evaluation device 36 in the manner of a mobile phone, smartphone or PDA is in communication, whose corresponding radio module with 38, flat screen with 40 and keyboard with 42 are designated. Optionally comes as an evaluation device 36, a laptop in question.

In the evaluation unit 36, the y and z coordinates of the hit point of a golf ball registered by the sensor 18, determined by the measuring and calculating circuit 30, are programmatically evaluated and graphically displayed together with the coordinates of the impact points of further ball strokes ,

The sensor 18 has the in Fig. 2 shown construction. It consists of a by means of a double-sided adhesive sheet 46 fastened to the striking surface 16 support plate 48 and a outside of this arranged protective plate 50. The support plate 48 may for example consist of glass fiber reinforced epoxy resin (preferably FR4 or FR5). The protective plate 50 may be made of plastic (preferably polyester). As both sides adhesive film 46 come under the brand names Tesa, Herma or Scotch commercially available films in question, preferably the adhesive force on the side connected to the support plate 48 side of the adhesive film is slightly larger than on the side to be joined with the impact surface 16.

On their mutually facing inner sides, the carrier plate 48 and the protective plate 50 are each provided with an electrically conductive layer 52 and 54, respectively. These may be semiconductor layers according to US Pat. No. 6,239,790 B1 act that have a certain linear electrical resistance. Between the two electrically conductive layers 52 and 54 spacers 56 are arranged in sufficient size and distribution, which ensure that the conductive layers 52, 54 only come into mutual contact when the flexible protective plate 50 regional or punctual, such as In a blow to a golf ball, a sufficient pressure is applied. As indicated at 58, the protective plate 50 is firmly bonded in the edge region with the support plate 48, but at least one not shown ventilation opening remains free, which is designed in the manner of a labyrinth seal, so that the sensor 18 is dustproof and splash-proof to IP54.

Also not shown are two printed traces extending along opposite edge portions of the carrier plate 48 and electrically connected along their length to the conductive layer 52. The support plate 48 is provided on its inside with two other printed conductors extending longitudinally opposite edge regions at right angles to the first-mentioned interconnects and contact in the assembled state over its length, the electrically conductive layer 54 on the protective plate 50. Alternatively, the tracks electrically connected to the conductive layer 54 could also be printed on the guard plate 50. Each of the 4 tracks is connected to the measurement and calculation circuit 30 via a signal line continuing in the cable 26.

If the flexible protective plate 50 is pressed in a position so far that the conductive layer 54 contacts the other conductive layer 52 on the support plate 48, after applying a certain reference voltage to the conductor tracks connected to one of the two layers between the In each case, a voltage is measured which is proportional to a change in the distances of the impingement point from the interconnects connected to the reference voltage, so that the y and z coordinates can also be determined after a calibration.

At the computer touchpad the US Pat. No. 6,239,790 B1 For example, the distances of a pinch point from the perpendicularly oriented tracks are calculated based on the amount of time the current takes to charge certain capacitors connected to the tracks. A longer path of the current through one of the conductive layers is tantamount to a greater resistance, ie a lower current intensity and thus a longer period of time for charging the capacitor in question.

In contrast, another, faster measuring method is provided for working with the new sensor because of the sudden loads with a pulse duration of 700 to 1200 microseconds. For this purpose, the in Fig. 3 shown substitute circuit diagram, wherein denoted by Yl and Yr on the left and right edges, for example, the conductive layer 52 traces, with Zo and Zu at the top and bottom of the conductive layer 54 arranged tracks, with Ryl, Ryr, Rzo and R, Rya and Ryb, and Rza and Rzb, the resistors in the kΩ region of the conductive layer 52 or the layer 54 are respectively designated between the impact point and the four interconnects.

bzw. zwischen Yl und Zo $$\mathrm{Vy}=\mathrm{Vref\; x}\left(\mathrm{Rya}+\mathrm{Ryl}\right)/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{Ryb}+\mathrm{Ryr}\right)$$

sind, wie ersichtlich, proportional zur Position des Auftreffpunktes in Z- und Y-Richtung auf der Sensorfläche. Durch Messung der Spannungen bei Druck auf z. B. vier symmetrisch um den Nullpunkt 22 des Koordinatensystems angeordnete Passermarken 44, die auf die Schutzplatte 50 im Bereich der aktiven Sensorfläche mit definiertem Abstand aufgedruckt sind, lässt sich das Verhältnis zwischen Spannung und Abstand feststellen und damit der Sensor kalibrieren, so dass aus den Spannungswerten eine Umrechnung der Position in mm, relativ zu dem auf den Sweet Spot gelegten Nullpunkt 22 des Koordinatensystems, möglich ist.Without touching the two layers 52, 54 at the point of impact, the resistance between a trace of the layer 52 and a trace of the layer 54 is infinite because of the spacers 56. Occurs selectively strong enough pressure on the protective plate 50, the two layers 52, 54 form the in Fig. 3 shown resistor network. In order to determine the coordinates of the impact point of a golf ball, a defined reference voltage V _{Ref is applied} alternately between Y1 and Yr during the pressure and simultaneously the voltage drop at high impedance is measured at one end of the other layer. The measured voltages between Zu and Yr $$\mathrm{vz}=\mathrm{Vref\; x}\left(\mathrm{rzb}+\mathrm{Rzu}\right)/\left(\mathrm{Rzo}+\mathrm{Rza}+\mathrm{rzb}+\mathrm{Rzu}\right)$$

or between Yl and Zo $$\mathrm{Vy}=\mathrm{Vref\; x}\left(\mathrm{Rya}+\mathrm{Ryl}\right)/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{ryb}+\mathrm{Ryr}\right)$$

are, as can be seen, proportional to the position of the impact point in the Z and Y directions on the sensor surface. By measuring the voltages at pressure on z. B. four symmetrically arranged around the zero point 22 of the coordinate system register marks 44, which are printed on the protective plate 50 in the region of the active sensor surface with a defined distance, can determine the relationship between voltage and distance and thus calibrate the sensor, so that from the voltage values a conversion of the position in mm, relative to the sweet spot placed on the zero point 22 of the coordinate system, is possible.

und für die y-Achse zwischen $$\begin{array}{l}\mathrm{Vref\; x}\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{Ryb}\right)/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{Ryb}+\mathrm{Ryr}\right)\mathrm{Volt\; und}\\ \mathrm{Vref\; x\; Ryr}/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{Ryb}+\mathrm{Ryr}\right)\mathrm{Volt}\mathrm{.}\end{array}$$

The measurements are continuously carried out at a suitable sampling frequency of 1 kHz to 10 kHz, suitably 4 to 8 kHz, currently preferably 6 kHz, to determine the position of a point of impact during the pressure duration in both To determine coordinate directions safely. In addition, the time of impact of the golf ball and the pressure duration can be determined by the fact that valid measurements can be distinguished from 0 volts by the constant end resistors Ryl, Ryr, Rzo and Rzu. The voltages that can be measured when the pressure is triggered lie between for the z axis $$\begin{array}{l}\mathrm{Vref\; x}\left(\mathrm{Rzo}+\mathrm{Rza}+\mathrm{rzb}\right)/\left(\mathrm{Rzo}+\mathrm{Rza}+\mathrm{rzb}+\mathrm{Rzu}\right)\mathrm{Volt\; and}\\ \mathrm{Vref\; x\; Rzu}/\left(\mathrm{Rzo}+\mathrm{Rza}+\mathrm{rzb}+\mathrm{Rzu}\right)\mathrm{volt}\end{array}$$

and for the y-axis between $$\begin{array}{l}\mathrm{Vref\; x}\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{ryb}\right)/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{ryb}+\mathrm{Ryr}\right)\mathrm{Volt\; and}\\ \mathrm{Vref\; x\; Ryr}/\left(\mathrm{Ryl}+\mathrm{Rya}+\mathrm{ryb}+\mathrm{Ryr}\right)\mathrm{volt}\mathrm{,}\end{array}$$

The sampling takes place with 8bit to 12bit, preferably with 10bit.

In Fig. 4 the essential parts of the measurement and calculation circuit 30 are shown. They are mounted in the housing 28 on a circuit board 60 and interconnected in the usual way.

Most important is a microcomputer labeled RAM of 62, FLASH memory, A / D converters, inputs and outputs (GPIOs) and serial interface, preferably UART and SPI. The microcomputer 62 controls the application of the reference voltage to the signal lines connected to the electrically conductive layers 52, 54, registers the voltages and associated times measured during the measurement processes, and calculates the coordinates of the points of impact. These are buffered and forwarded via the radio module 34 with an antenna, preferably a ceramic antenna 35, to the evaluation device 36. The power supply is a battery 64, the charge controller is shown at 66. The charging takes place via a socket 68, preferably a mini-B type USB socket or a 2.5 mm jack socket. About this socket and the microcomputer 62 can be reprogrammed.

The measuring and calculating circuit 30 further includes a rotation rate sensor (gyroscope, gyro) 65 which is mounted in the housing 28 so that its sensitive axis substantially parallel to the impact surface 16 and the lower edge, ie normal to the plane of the pivoting movement of the reference point 22 at Putting, extends. Suitable yaw rate sensors 65 are commercially available, for example, under the designations Epson XV-3500TB, Murata Gyrostar, InvenSense IDG-300 and Analog Devices ADXRS 300. In cooperation with the microcomputer 62, the rotation rate sensor 65 determines a series of measured values, for. 100 per second, the angular velocity of the club head 16 during its reciprocal swing motion during puttering, which, over time, is about 3 seconds. plotted, a characteristic similar to the one in Fig. 5 shown diagram. In it, the rest or starting position is shown at A. From here, the angular velocity in the backward direction initially increases, then decreases until at B the end of the backswing is reached in the rearmost position of the clubhead. There, the angular velocity in the direction of impact is zero and the forward motion begins. It becomes faster, then progressively slower, until C hits the golf ball at C, until at D the end of the forward swing in the foremost position of the clubhead is reached. This is followed by an initially accelerated, then delayed backward movement, until the clubhead returns to the starting position at E.

From the course of the characteristic of the angular velocity according to Fig. 5 the acceleration can be deduced. Integral formation obtains the angles traveled and can thus determine the positions of the putter at the end of the backswing and the forward swing and control the vertical position of the face when hitting the ball. The multiplication of the angular velocity with a body size dependent radius gives the speed of the clubhead during the individual phases of the putting and the moment of impact on the ball. Moreover, the characteristic provides the exact duration of the backswing and forward momentum until the ball is hit. Golfers pay particular attention to the quotient of these time periods as well as the shape of the characteristic curve in the transition range from the return to the forward momentum, which can reveal, for example, an uncertainty expressing itself by hesitation.

With particular advantage, the measurement signals of the rotation rate sensor 65 can be used to control the function of the plate-shaped sensor 18. Namely, the latter needs to be activated by the microprocessor 62 only when the measurement results of the rotation rate sensor 65 are within certain limits and thereby indicate that a putt has been started with an acceptable backswing and beginning of the forward swing. By activating the plate-shaped sensor 18 only during the forward swing immediately before the impact against the ball and after pre-checking the initial movement, it is achieved that not every impaction of the striking surface against a hard object and also a slow test swing in the evaluation of concentrated concentrated putts arrives.

Further advantages are the use of a two- or three-axis rotation rate sensor 65, which in addition to the sensitive axis parallel to the in Fig. 1 Having shown y-axis at least one further sensitive axis parallel to the x-axis and / or to the z-axis. Alternatively, three separate rotation rate sensors could be used for each one of the said axes. In this way, starting from the starting position A of the golf club before the start of the backswing, the rotation rates z. B. measure all three axes and determine the angular position of the clubface.

The angular velocities determined by the microcomputer 62 from the measuring signals of the rotation rate sensor 65, as well as the coordinates of the points of incidence determined from the measuring signals of the plate-shaped sensor 18, are transmitted via the radio link 34, 35, 38 to the evaluation unit 36 where they are evaluated and visualized according to the program.

In Fig. 6 a quick-release mechanism for releasably attaching the housing 28 of the measuring and calculating circuit 30 is shown on the shaft 12 of the golf club, preferably according to Fig. 1 on the club head 10 or on the striking surface 16 opposite side of the shaft 12. As shown, the housing 28 is grooved on the side adjacent to the shaft 12 with a diameter slightly larger than the shaft diameter sized. Between the housing 28 and the shaft 12, a rubber insert 70 is used, which can also be glued to the housing 28 and can help to make the housing dustproof and splash-proof to IP54. The connection of the housing with the shaft 12 by means of a flexible plastic strap or a strap 72, z. As a textile tape, which can be rubberized on the inside. One end of the tension band 72 is fixed to a fixedly connected to the housing 28 deflection pin 74. On the opposite side of the deflecting pin of the housing 28, the clamping band is placed around the shaft 12 is connected to a clamping or locking lever 76 which engages in a recess 78 of the housing 28 and biases the clamping band 72 during its closing movement. It is understood that there are a variety of other mechanisms for mounting the housing 28 on the shaft 12, z. B. hooks on at least one side of the housing 28, in the guided around the opposite side of the shaft 12 clamping rubbers are hooked.

The evaluation unit 36 operates in the master mode in order, if necessary, to receive, store and evaluate the measurement data of a plurality of measurement and calculation circuits 30, which are each transmitted to the evaluation device 36 by means of Bluetooth via a suitable transmission protocol, preferably SPP or HDI and to visualize. In this way, for. B. Two or four players directly compare their evaluated data in a common graph.

Claims (11)

1. Device for monitoring the accuracy with which a golf club is guided in the swing and strikes a golf ball with the striking face (16) of its club head (10), comprising an electronic measuring and computing circuit (30) mounted, together with an electrical voltage source (64), in a housing (28) that can be releasably fastened in a defined position on the shaft (12) or on the back of the head (10) of the golf club and cooperating with the plate-shaped sensor (18) via signal lines (26), by means of which circuit a measuring process for determining an impact point can be performed in the event of an impact on a golf ball, characterised by

   - a plate-shaped sensor (18) which can be releasably fastened on the striking face (16) in a defined position and by means of which the exact point of the position of the impact point when a golf ball is struck can be located,

   - the design of the plate-shaped sensor (18) as a touchpad comprising a rectangular support plate (48) having a first electrically conductive layer (52) applied to its front, which is connected along two opposing edge regions to a printed conductor trace connected to a signal line, and having a flexible protective plate (50) which is arranged in front of the support plate (48) and has a second electrically conductive layer (54) which has been applied to the reverse thereof and is connected along two opposing edge regions to respective printed conductor traces, which are connected to a signal line and extend transversely with respect to the conductor traces connected to the first conductive layer (52), the conductive layers (52, 54) being separated by resilient spacers (56), the restoring force of which has been selected in such a way that there is temporary contact between the conductive layers (52, 54) only in the event of an impact on a golf ball at the impact point, whereby the measuring process for determining the coordinates of the impact point in relation to the position of a predetermined reference point (22) can be performed,

   - a rotation rate sensor (65), mounted in the housing (28), the sensitive axis of which sensor extends essentially parallel to the lower edge of the striking face (16), and which sensor cooperates with the measuring and computing circuit for determining the direction of rotation, angular speed and duration of the phases of the backswing and forward swing motions of the club head (10), and

   - a radio module (34), connected to the measuring and computing circuit (30), for the wireless transmission of the measurement results to an evaluation device (36) in the manner of a mobile phone, smart phone or PDA for the program-controlled evaluation and display of the measurement results on its display screen (40).
2. Device according to claim 1, characterised in that the protective plate (50) is securely integrally bonded to the support plate in the edge region, except for at least one air inlet and outlet opening.
3. Device according to either claim 1 or claim 2, characterised in that the support plate (48) is at most 1 mm thick and is flexible.
4. Device according to any of claims 1 to 3, characterised in that the active sensor face of the sensor (18) is approximately 45 to 65 mm wide, and for putters approximately 16 to 20 mm high, and for clubs for pitching and chipping 20 to 30 mm high.
5. Device according to any of claims 1 to 4, characterised in that the plate-shaped sensor (18) can be releasably fastened to the striking face (16) by means of a foil (46), which is adhesive on both sides.
6. Device according to any of claims 1 to 5, characterised in that the rotation rate sensor (65) has one or two additional sensitive axes, which extend perpendicular to a planar face enclosing the striking face (16) and/or parallel to an axis located in the striking face (16) and forming a right angle with the lower edge of the striking face.
7. Device according to claim 1, characterised in that the signal lines (26) have a disconnectable plug connection (24) between the sensors (18, 65) and the measuring and computing circuit (30).
8. Device according to claim 1, characterised in that the housing (28) of the measuring and computing circuit (30) can be fastened in a frictionally connected manner to the shaft (12) via a rubber-type contact face (70) by means of a clamping strip (72).
9. Method for determining the position of the impact point of a golf ball on the striking face (16) of a golf club by means of a device according to claim 1, characterised in that, during the time of the contact between the conductive layers (52, 54) at the impact point, an electrical voltage is alternatingly applied between respective opposing edge regions of one of the conductive layers (52, 54), and a voltage measurement is performed at at least one of the edge regions of the respective other conductive layer (54, 52), and in that the voltage values are converted into coordinates of the impact point by means of a proportionality factor.
10. Method according to claim 9, characterised in that an electrical voltage is applied to each one of the conductive layers (52, 54) only once the measurement results, ascertained in cooperation with the rotation rate sensor (65), are located within a certain frame and thereby signal the course of a normal backswing and forward swing motion of the club head (10) until just before a golf ball is struck.
11. Golf club comprising a device according to any of claims 1 to 8, characterised in that it has a mount for a weight, which mount can be releasably securely clamped in its hollow shaft (12) and can be pulled out therefrom.

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