WO2002083252A1

WO2002083252A1 - Device for measuring speed, in particular instantaneous speed and impact speed of a golf club

Info

Publication number: WO2002083252A1
Application number: PCT/CH2002/000201
Authority: WO
Inventors: Jean-Daniel Carrard
Original assignee: Jdc Electronics S.A.
Priority date: 2001-04-11
Filing date: 2002-04-10
Publication date: 2002-10-24
Also published as: FR2823447B1; FR2823447A1

Abstract

The invention concerns a device for measuring speed (10), in particular maximum instantaneous speed or the impact speed of a golf club, comprising a speed sensor (11), means for processing shaped signals from signal transforming means and calculating means, means for transmitting signals from the sensor (11) to the processing means, and a device for displaying (14) the measured speed. A push-button (16) enables the selection of the measurement option and the triggering of the device. The speed sensor comprises a propeller (20) integral with a circular permanent magnet (21). The processing means comprise a coil for detecting the duration of each rotation cycle of the propeller and for determining an instantaneous linear speed of the golf club at a given moment, thereby enabling to determine either the maximum speed or the impact speed. Said device can easily be fixed at the base of the club handle (100) with positioning means (34).

Description

DEVICE FOR MEASURING A SPEED, ESPECIALLY AN INSTANT SPEED AND AN IMPACT SPEED OF A GOLF CLUB

Technical Field The present invention relates to a device for measuring a speed, in particular an instantaneous speed and an impact speed of a golf club, comprising a speed sensor, means for processing signals from this sensor, means for transmitting signals from the sensor to the processing means and an electrical supply to said processing means, said speed sensor comprising a propeller rotating about an axis of rotation substantially parallel to the movement of the golf club and to minus a permanent magnet secured to this axis of rotation.

PRIOR ART There are currently several types of device for measuring the speed of a golf club and in particular the maximum speed reached by the club just before impact with the ball.

One type of device uses a radar and measures speed at different times during the movement of the club. This measurement has the advantage of being very precise. On the other hand, it requires a heavy and expensive installation and can therefore only be used in a location provided for this purpose. It can in no case be used throughout a course, during training or competitions.

Another type of measurement uses a metallic wire heated by the passage of an electric current. The movement of the golf club has the effect of cooling the wire to a temperature which depends on the speed of movement. This technology requires the precise measurement of the wire temperature, then the transmission of the result of this measurement to a display device. However, the most important drawback of this device is the very high energy consumption it generates, which makes it too heavy and impractical. Finally, it is also possible to have an accelerometer at the end of the club. On the one hand, this implies a high manufacturing cost due to the cost of the accelerometers, and on the other hand, the result is unreliable. Indeed, the result of the measurement very strongly depends on the radius of the movement of the head of the club, which itself depends on the size of the player and his way of playing.

Also known from Japanese publication JP 11 326357 is a device for measuring the speed of the head of a golf club during swing. This device measures the pressure of the wind generated during the swing and consists of a rotor in the form of a propeller linked to a current generator connected to a small recorder of the quantities of electricity generated. The club speed is thus determined from the recorded measurements. The measurements made with this type of device are not precise because the positioning of the axis of rotation of the propeller directly linked to the generator generates friction and inertia forces which distort the measured speed. In addition, the fact that the device is placed on the head of the club is very disturbing, especially visually, for the player, even if the size of this device is not very important. In addition, this location slows the penetration of the club into the air during a swing.

European publications EP 0 703 458 and German DE 197 25 904 relate to devices intended to control the speed of skiers and which, even if they were used on a golf club, by design, would not make it possible to obtain with precision all the information provided by the device according to the invention.

SUMMARY OF THE INVENTION The present invention proposes to overcome the drawbacks of the devices of the prior art by producing a device which allows the measurement of different parameters related to the use of a golf club, in particular the speed of impact. of the club on the ball and the maximum instantaneous speed of movement of said club during the swing, which, moreover, is small and light, therefore easily transportable, reliable and precise and which can be put on and taken off very easily from the club.

These aims are achieved by a device as defined in the preamble and characterized in that the permanent magnet has an annular shape, is arranged on the axis of rotation of the propeller and is associated with an induction coil arranged to detect the magnetic field generated by said magnet, during the rotation of the propeller caused by the movement of the club, and generate electrical signals transmitted to the processing means and representative of the duration of a revolution of the propeller, and in this that said processing means are arranged to determine from said received signals an instantaneous speed of the golf club and / or the speed of the club at the time of its impact on a golf ball.

According to a preferred embodiment, when measuring the instantaneous maximum speed of the club, the processing means are arranged to measure the minimum duration of one revolution of the propeller and, when measuring the impact speed of the club on the ball, these processing means are arranged to measure the duration of the rotation of the propeller which precedes the impact.

Advantageously, the propeller is arranged in a cylindrical housing having a shape such that the air flows around the handle of the club, at the exit of the housing, practically without turbulence. For this purpose the cylindrical housing of the propeller is integral with a base of rounded frustoconical section.

Preferably, the axis of rotation of the propeller is mounted in two support elements, at least the support element which is arranged on the side of the club being provided with a friction reduction element. Said friction reduction element may be a sapphire bearing. In the preferred embodiment, the pitch of the propeller is such that its maximum speed is less than 2,500 rpm and preferably equal to 2,000 rpm when measuring an instantaneous maximum speed of the club. Preferably this pitch is approximately equal to 25 mm.

According to a preferred embodiment, the speed sensor, the processing means, the transmission means, the display means and the electrical supply are arranged in the same housing.

According to an alternative embodiment, the transmission means comprise a radio wave transmitter arranged to transmit the signals from the speed sensor to a remote receiver. This receiver can be associated with a display device housed in a case of the watch case type.

In all embodiments, the device is provided with rapid positioning means on the bottom of the club handle.

Brief description of the drawings

The present invention and its advantages will be better understood with reference to the description of different embodiments and to the accompanying drawings in which:

FIG. 1 is a front view of the device according to the invention fixed on a club handle,

FIG. 2 is a view along arrow A of the device of FIG. 1,

FIG. 3 is a side view of the device in FIG. 1,

FIG. 4 is a sectional view along line ll of the sensor of the device of the invention, FIG. 5 is a schematic view of a first embodiment of a part of the device according to the invention,

FIG. 6 illustrates another embodiment of a part of the device, similar to that of FIG. 5,

FIGS. 7 and 8 respectively illustrate the transmitter and the receiver of an alternative embodiment of the device according to the invention, and

FIG. 9 represents an ideal signal as used in the device of the invention.

Manner (s) of carrying out the invention

With reference to these figures, the device 10, intended to be fixed to the handle 100 of a golf club, essentially comprises a speed sensor 11, means 12 for transmitting signals from the sensor 11 to processing means 13, a display device 14 and means for rapid positioning

34 on the handle of the club 100. The device 10 also includes an electrical energy supply and a switch 16 for switching on and off the measuring device and for selecting different options for this device. All these components are housed in the same box 1 of substantially rectangular parallelepiped shape, the bottom V of which is bent along a radius of curvature equal to the radius of the bottom of the handle of the club 100. This box is preferably glued in a completely sealed manner and is very robust so as not to be sensitive to shocks.

The speed sensor 11 is illustrated in detail in FIG. 4. It comprises a substantially cylindrical housing 17 secured to a base 15 of rounded frustoconical section. This housing is completely open at its upper end 17a and has at least two openings 17b at its lower end. It is also provided, at each of these ends, with at least one support element respectively 18a, 18b intended to maintain in position a axis of rotation 19 disposed parallel to a generator of the housing 17. This axis 19 constitutes the hub of a propeller 20. This propeller is made of a light and robust material, so as to have minimal inertia. To improve the accuracy of the measurements, the axis 19 is linked to the support element 18b by a friction reduction element such as a sapphire bearing 9. It is obvious that one can also make the connection with the the support element 18a with an identical bearing.

When in use, the device 10 is fixed by the positioning means on the bottom of the club handle 100 so that the axis of rotation 19 of the propeller 20 is parallel to the direction of movement of the club during a swing and perpendicular to the longitudinal axis of the club head.

A permanent magnet 21 of annular shape is fixed on the axis of rotation 19 of the propeller 20, so that the rotation of this propeller 20 causes the rotation of the axis and that of said magnet 21. The propeller has a step such that it rotates at a maximum speed less than 2,500 revolutions / second and ideally close to 2,000 revolutions / second when the device of the invention is used to measure the maximum speed of a golf club. In order to obtain sufficient measurement accuracy, the pitch of this propeller is approximately equal to 25 mm.

The transmission means 12 comprise an induction coil 22 arranged to detect variations in the magnetic field generated by the magnet 21. This coil can be formed of a track printed on a printed circuit or of a conductive wire wound around 'a ferrite core or in the air. The number of turns must be sufficient so that, at the distance which separates the magnet 21 from this coil 22, a rotation of the magnet is detected.

The processing means 13 receive electrical signals from the variation of the magnetic field due to the rotation of the magnet 21 and transform these signals into a speed. These processing means 13 essentially comprise means 23 for shaping the signal and calculation means 24. The shaping means 23 can be produced in different ways, in particular those illustrated in FIGS. 5 and 6.

The embodiment illustrated in FIG. 5 represents an example in which the coil 22 includes a few turns printed on a printed circuit board. The signal generated in the coil by the rotation of the magnet is introduced into an amplifier 25. The amplified signal leaving the amplifier is introduced into the calculation means 24 which are composed in this example, of a microcontroller 26 controlled by a quartz 27. This microcontroller transforms the signal leaving the amplifier 25 into a speed of movement of the golf club, according to a method which is explained in more detail below.

In the embodiment illustrated in Figure 6, the coil 22 preferably comprises about a hundred turns, wound around a ferrite core. The sinusoidal signal leaving the coil is transformed into a square signal by means of a transistor 28. This square signal is introduced into the microcontroller 26 to be processed there.

The value measured by the sensor 11 and processed by the microcontroller 26 is displayed on the display device 14, generally formed by a liquid crystal display. However, this display is not essential. The measured values can also be stored and read later using a suitable reader.

In an alternative embodiment, the coil 22 can be dissociated from the printed circuit forming the processing means 13 and arranged near the cylindrical housing 17 by being linked to a radio transmitter 110 also placed near this housing. In this case, the signals from the coil 22 are introduced, with or without shaping processing, into the transmitter 110, illustrated in FIG. 7, which transmits them, by means of an appropriate antenna 111, to a receiver 120, illustrated by FIG. 8, itself provided with an antenna 121. The receiver supplies these signals to a microcontroller 26 which processes them as in the case explained with reference to the preceding figures.

In this embodiment, it is possible to place the receiver 120 in a device such as a wristwatch or similar to a wristwatch, or a case placed in a pocket or the belt of a user. It is also possible to store the information to display it later.

The measuring device according to the present invention makes it possible in particular to determine the instantaneous maximum speed of the golf club and the speed at the time of the impact of the club with the ball. It is also possible to determine an acceleration, for example the maximum acceleration. Measuring acceleration also helps determine a force.

The device is described below in an embodiment for measuring the maximum instantaneous speed.

To this end, this device 10 can be engaged manually by means of the switch 16, produced for example in the form of a push button illustrated in FIG. 5. It can also be engaged automatically as soon as a speed greater than a certain threshold, for example 50 km / h is detected.

When a stroke is made, the club is moved, which has the effect of generating the rotation of the propeller 20, and consequently, the rotation of the permanent magnet 21. This rotation of the magnet generates a variation of magnetic field which is detected by the coil 22. The signal leaving the coil is processed so as to provide a substantially rectangular signal as illustrated in FIG. 9. The microcontroller 26, controlled by a quartz, measures the time interval between two consecutive consecutive flanks, for example two falling edges of the signal. All consecutive intervals are determined for each stroke. The shortest interval, marked with reference 29 in FIG. 9, corresponds to the maximum instantaneous speed of the club.

The duration of this interval corresponds to the time necessary for the magnet 21 to make a complete revolution. By knowing the pitch of the propeller and the duration of an interval, it is therefore possible to know the speed of the club during this interval.

The speed calculated by the microcontroller 26 is displayed on the display device 14 and / or stored.

When a stroke is made, the club is usually slowed down slightly before hitting the ball. Thus, the speed immediately before impact does not necessarily correspond entirely to the maximum speed.

In order to determine this impact speed, each time interval between two similar flanks of the input signal in the microcontroller 26 is measured, as before.

Right after the impact, the club speed slowed down very sharply. The last interval before this strong deceleration, illustrated by FIG. 9 under the reference 30, can be detected and corresponds to the impact speed.

It is also possible to measure the maximum speed and the speed of impact for a given blow, then to compare these two values, which makes it possible to determine if the player slows down his club before the impact.

Thanks to the extremely low inertia of the propeller, any speed variation acts on the measured interval, so that the instantaneous measurements are very precise. By deriving the measurement of the club speed as a function of time, it is possible to know the instant acceleration of this club. It is therefore possible to deduce from it the force which is developed during the movement.

The operating mode of the device can be very variable, depending on demand. In particular, the display 14 can be used to indicate the maximum speed value, the impact speed, a maximum speed over an entire golf course or any other indication which may prove useful or desirable.

This display can be permanently on or go to sleep after a certain time.

It is also possible to provide a display in different measurement units, set at the factory or adjustable by the user, for example by means of a push button.

The device according to the invention is very light and absolutely does not disturb the way of playing. In fact, it is not felt by the player. It is very simple to fix on the club since it can be put in place with one hand by means of positioning means 34. These positioning means consist of an arched lever fixed on the rear part of the device by means a screw 35. The two ends 34a and 34b of this lever are in the form of hooks perpendicular to the axis of the handle of the club which hook onto said handle 100 when the device is put in place, the curved bottom of the housing 1 of the device thus pressing against the handle 100 of the club. In addition, the fact that the lower openings of the housing 17 of the sensor 11 open onto a base of frustoconical section guarantees that the outgoing air flows around the handle of the club practically without turbulence, which does not disturb the penetration coefficient of the club in the air during a swing. The electrical supply of the various electronic components is done by a battery housed in the closed housing 1. Given the low consumption of the components used, a conventional battery allows the device to be used intensively for several years. It is therefore not necessary to provide for the possibility of replacing the battery.

The device can be used to measure the maximum speed of a moving object other than a golf club. It can in particular be applied to a tennis racket, an arrow, a model, or in industrial sectors. In some cases, it is possible to read the speed immediately on a display, in others, this speed is memorized and can be read later.

Since the device can measure instantaneous speeds at different times, it is also possible to deduce accelerations and forces. It can therefore find an application as an accelerometer.

Claims

1. A device for measuring a speed, in particular an instantaneous speed and an impact speed of a golf club, comprising a speed sensor, means for processing signals from this sensor, means for transmitting signals from the sensor to the processing means and an electrical supply to said processing means, said speed sensor (11) comprising a propeller (20) rotating about an axis of rotation (19) substantially parallel to the movement of the club golf course and at least one permanent magnet (21) integral with this axis of rotation, characterized in that the permanent magnet (21) has an annular shape, in that it is arranged on the axis of rotation (19) of the propeller (20) and is associated with an induction coil (22) arranged to detect the magnetic field generated by said magnet (21), during the rotation of the propeller (20) caused by the movement of the club , and generate electrical signals transmitted to the processing means and representative of the duration of a rotation of the propeller, and in that said processing means (13) are arranged to determine from said received signals an instantaneous speed of the golf club and / or the speed of the club at the time of its impact on a golf ball.

2. Device according to claim 1, characterized in that, during the measurement of the instantaneous maximum speed of the club, the processing means (13) are arranged to measure the minimum duration of one turn of the propeller (20) .

3. Device according to claim 1, characterized in that, during the measurement of the impact speed of the club on the ball, the processing means (13) are arranged to measure the duration of the rotation of the propeller (20 ) which precedes the impact.

4. Device according to claim 1, characterized in that the propeller (20) is arranged in a cylindrical housing (17) having a shape such as air flows around the handle of the club, at the exit of said housing, practically without turbulence.

5. Device according to claim 4, characterized in that the cylindrical housing (17) is integral with a base (15) of rounded frustoconical section.

6. Device according to claim 1, characterized in that the axis of rotation (19) of the propeller (20) is mounted in two support elements (18a, 18b), at least the support element (18b) , which is arranged on the side of the club, being provided with a friction reduction element.

7. Device according to claim 6, characterized in that said friction reduction element is a sapphire bearing (9).

8. Device according to claim 1, characterized in that the pitch of the propeller (20) is such that its maximum speed is less than 2,500 revolutions / second and preferably equal to 2,000 revolutions / second during the measurement of an instantaneous maximum speed of the club.

9. Device according to claim 8, characterized in that the pitch of the propeller (20) is approximately equal to 25 mm.

10. Device according to claim 1, characterized in that the speed sensor (11), the transmission means (12), the processing means

(13), the display means (14) and the power supply are arranged in the same housing (1).

11. Device according to claim 1, characterized in that the transmission means (12) comprise a transmitter (110) of radio waves arranged to transmit the signals from the speed sensor (11) to a remote receiver (120).

12. Device according to claim 11, characterized in that the receiver (120) is associated with a display device housed in a case of the watch case type.

13. Device according to claim 1, characterized in that it is provided with rapid positioning means (34) on the bottom of the club handle (100).