GB2096469A

GB2096469A - Golf training device

Info

Publication number: GB2096469A
Application number: GB8208561A
Authority: GB
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1981-04-10
Filing date: 1982-03-24
Publication date: 1982-10-20
Also published as: GB2096469B; JPS57168678A; AU8243282A; AU535418B2; JPS6138714B2

Abstract

A golf training device includes a golf club which has a club head having a magnetic substance in at least a part of said club head, a detecting device fixed to plural positions of a base to output detecting signals for movement of said club head by detecting variation of said signals per time caused by the movement of said club head, and means for displaying the movement of said club head depending upon said signals from said detecting devices, wherein said detecting device comprises a signal producing part for feeding signal to the magnetic substance of said club head and a detecting part formed in one piece with said signal producing part to detect variation of signal per time caused by mutual interference of said magnetic substance and said signal producing part. <IMAGE>

Description

SPECIFICATION Golf training device The present invention relates to structure of a detecting device for detecting movement of the head of a golf club. More particularly, it relates to a golf training device having a detecting means in a club head such as an iron club heed made of a magnetic material which detects movement of the club head without attaching any special device to the club head.

It has not been proposed to use a simple, compact golftraining device which judges whether or not swinging of a golf club is right and instructs judge ment to a player.

It is an object of the present invention to provide a golf training device which allows a playerto learn himself a correct swinging form easily and provides a highly precise data of measurement.

The foregoing and the other objects of the present invention have been attained by providing a golf training device including a golf club which has a club head having a magnetic substance in at least a part of said club head, a detecting device fixed to plural positions of the base to output detecting signals for movement of said club head by detecting variation of said signals per time caused by the movement of said club head, and means for displaying the movement of said club head depending upon said signals from said detecting devices, wherein said detecting device comprises a signal producing part for feeding signal to the magnetic substance of said club head and a detecting part formed in one piece with said signal producing part to detect variation of signal per time caused by mutual interference of said magnetic substance and said signal producing part.

Figure lisa schematic view of an embodiment of the golftraining device of the present invention; Figure 2 is a sectional view of an important part of the golf training device; Figure 3 is a schematic view illustrating arrangement of the golf training device; Figure 4 is an enlarged perspective view of the detecting device; Figure 5 is a schematic diagram illustrating the characteristic of the detecting device; Figure 6 is a characteristic curve of the detecting device; Figure 7 is a schematic view of another embodiment of the present invention; Figure8 is a diagram of timing cha rts of zero-cross waveforms and detected outputs of detecting devices; Figure 9 is diagram of waveforms in data processing of detection output; Figure 10 is a block diagram of a control circuit;; Figure 11 a and bare diagrams of output W~aveforms of detecting devices when an iron or wooden club is used; and Figure 12 a and bare diagrams of output waveforms of detecting devices when a putter is used.

An embodiment of the present invention will be described with reference to drawing. In Figures 1 to 4, the reference numeral (1 ) designates a golf club such as an iron club having a club head (2) made of a magnetic material, (3) designates a golf mat, (4) designates a base formed by a plastic resin in which two recesses for fitting each detecting device spaced apart with a distance L in the direction of a correct swinging and a recess spaced apart with a distance D from one of the recesses in the direction perpendicularto that of the swinging are formed by precise machining operation, (5) designates a processor for processing signals from the detecting devices to calculate the speed and the direction of the swinging and display the calculated figures, (6) designates a cable for transmitting signals from the detecting devices to the processor (5), (7) designated a golf ball, (8a, 8b, 8c) respectively designate detecting devices fitted to the recess formed in the base (4), the detecting devices detecting the variation of the signal caused by movement of the club head (2) and outputting the detecting signal of the movement of the club head (2) to the processor (5), (9) designate permanent magnets which respectively form detecting devices and work as signal producing part such as a magnetic flux producing part for forming magnetic flux in the club head (2), (10) designates a magnetic flux searching coil as a detecting part such as a magnetic sensor which detects variation of magnetic flux per unit time caused by mutual inteference of the moving club head (2) to the permanent magnet (9) to output voltage.The searching coil is wound on a protecting frame (11) fitted to the side surface of the permanent magnet (9) as a onepiece structure with the permanent magnet (9).

The operation of the structure of the golf training device will be described with reference to Figures 5 and 6.

The operation of the detecting device (8a), for example, of the present invention will be described with reference to Figure 5. When the N-pole is given to the upper part of the permanent magnet (9), the side surface of the club head (2) facing the permanent magnet (9) is magnetized with the S-pole and magnetic flux passing the side surface is crossed to the magnetic flux searching coil (10) thereby producing voltage e0acrosstheterminals of the searching coil (10).

The voltage O0 is expressed by the following: eO= - NvhA dy dy wherein N is the number of turns of the searching coil, A is effective sectional area of the searching coil, vh is speed of movement of the magnetized club head, B is density of the magnetic flux in the center of the searching coil andy is coordinate axis in the direction of swinging the club head.

Figure 5 illustrates relationship of the positions of the moving club head (2) to the voltage eO. When the positions of the club head are expressed by three positions a, b and c, the voltage e0 is shown by a waveform wherein the voltage e is maximum at the position 2a of the club head, zero at the position 2b and minimum at the position 2c (The waveform is referred hereinafter to zero-cross waveform).

The detection of the movement of the golf club (1 ) by the voltages ea, eb and ec detected by the detecting device when the golf club (1 ) comprises the detecting device (8a) having the above-mentioned characteristic is swung, will be described with reference to Figures 3 and 6. When the face of the club head (2) in the swinging is inclined atX" to the face ofthe club head in the correct swinging, the waveforms of the voltages ea, eb and ec are produced in the order.The angle of inclination 3( of the face of the club head is given as follows:

wherein time difference between the waveforms of the voltages ea and eb is tv, whereby moving speed vh of the club head is given as vh = Utv1 and time difference between the waveforms of the voltages ea and ec is tv2.

The operation of the processor (5) is carried out such a mannerthatthe progressedtimetv1 between points of zero of the voltages ea and eb and the prog ressed time tv2 between points of zero of the voltages ea and ec are respectively obtained by using clock pulses of a quartz oscillator having the precise inherent oscillation and these values are substituted in the operating circuit for vh and x to calculate and display the moving speed and the inclination angle of the face of the club head (2).

Thus, in the golf club such as an iron club having a club head made of magnetic material, magnetic flux in the club head (2)nmagnetized by the permanent magnet (9) of the detecting device (8a) is detected by the magnetic flux searching coil (10) without applying a special device to the golf club and positional relationship of the detecting devices can be precisely obtained whereby it is possible to conveniently attain a precise measurement On the other hand, in a golf club (1') such as a wooden club having the club head (2') made of a non-magnetic material as shown in Figure 7, a permanent magnet (2") such as rubber magnet which has a magnetism direction cooperating with the magnetic substance or the magnetic flux producer is fixed to the club head (2') whereby the moving speed and the moving direction of the club head in the swinging can be obtained.

In the embodiment, the detecting device compris ing the permanent magnet and the magnetic flux searching coil is used. It is possible to form a detecting device by using an exciting coil, that is, a combination of an iron core and a coil to measure the moving speed and the moving direction of the club head by pulse component obtained by passing a constant direct current It is also possible to use any magnetic sensor such as Hall element responsive to magnet ism other than using of the searching coil.

In case when induction noise in air such as induction noise caused by a high voltage supply line and human body substantially affects to a magnetic sensor as a detecting device, the magnetic sensor is provided with a noise shielding sheet obtained by bonding a non-magnetic sheet or an electroconductive metallic foil to a plastic resin sheet so as to weaken eddy current causing disturbance of the waveform, whereby the noise can be reduced. The noise shielding sheet can be fabricated by plating a non-magnetic material or a conductive metallic material on a plastic resin sheet so as to further improve accuracy of measurement.

It is also possible to use a sound-wave producer for producing sound wave as a signal producing part other than the magnetic flux producing part to utilize Doppler effect of sound wave whereby the moving speed and the moving direction of the golf club can be measured.

Now, a detection and display system of the present invention will be described in more detail with reference to Figures 8 to 12. When zero-cross waveforms ea, eb and ec shown in Figure 6, which are produced by passing the club head near or just above each magnetic sensor 8a, 8b and Sc as a detecting device, are detected by a voltage detecting element, detection outputs Ea, Eb and Ec are obtained as shown in Figure 8. The detection outputs are utilized for judgement of swinging.

When the speed of swinging club is to be detected, a pulse is produced by detecting the detection output Ea to use it as a setting input for a flip-flop and a pulse is produced by detecting the detection output Web to use it as a resetting input for the flip-flop whereby a pulse output for measuring speed (Ef) is obtained as shown in Figure 9. A clock signal En is output by the logical product of the pulse output Ef and a clock pulse of a high-frequency oscillator (21) described below. Time different TV between detection outputs Ea and Eb each detected by the detecting devices 8a and 8b is obtained by counting the clock frequency contained in the signal En by a binary counter.The speed of swing can be, therefore, obtained by dividing the distance L between the detecting devices 8a and 8b by the time difference Tv.

When the direction of the club face is to be detected, a pulse is produced by detecting the detection output Ea ofthe detecting device (8a) to use it as a setting input for two flip4lops. A pulse produced by the detection output Eb of the detecting device 8b is applied as a resetting input to one flip-flop to produce a detection output Ep shown in Figure 9, whereas a pulse produced by the detection output Ec of the detecting device Sc is applied as a resetting input to the other flip-flop to produce a detection output Eg also shown in Figure 9, whereby a pulse output for measurement Er can be obtained depend ing upon time difference between the detection out puts Ep and Eg. As similar to the detection of speed, a clock signal Em is output by the logical product of the output for measurement Er and the clock pulse of the high-frequency oscillator (21). The clock from quency in the clock signal Em is counted by a binary counter to obtain a time difference Tc. The inclina tion of angle X , i.e. the direction of the club face, is obtained by calculating the time difference and mutual distances L and D of the detecting devices 8a, 8b and 8c.

An embodiment of the control circuit (14) of the present invention utilizing the aforementioned principle of detection will be described in detail.

In Figure 10, the reference numerals 15a, 15b, 15e respectively designate zero-cross waveform detecting circuits for detecting zero-cross waveforms of the detecting devices 8a, 8b, 8c; 16a, 16b, 16e respectively designate waveform processing circuits for converting the zero-cross waveforms into desired detection waveforms, and specifically, the detection waveforms Ea, Eb, Ec as shown in Figure 8 are produced.

The reference numeral (17) designates an interface circuit for converting the output signals from the waveform processing circuits into signal forms which can be treated by a central control circuit 18 described below, the interface circuit including binary counters (not shown) for counting number of clock pulses contained in the clock signals En, Em and the count outputs from the binary counters being held for a time and then fed to the central control circuit (18).The interface circuit (17) includes input terminals (17a), (17b), (17c) and outputterminals (17d), (17e), (17f). (18) designates a central control circuit consisting of a microcomputer which operates to display the speed of swing and the direction of a club face depending upon signals supplied from the interface circuit (17); (25), (20) respectively designate a display unit and a speaker, both outputting a result of operation of the central control circuit (18); (21) designates a high-frequency oscillator for feeding high-frequency pulses to the interface circuit (17); (22) designates a power source circuit for supplying power source to a measuring system (S) which comprises the zero-cross waveform detecting circuits (15a). (15b), (15c), the waveform processing circuits (16a), (16b), (16c), the interface circuit (17) and the high-frequency oscillator (21); (23) designates a set switch which releases the data-input prohibiting condition ofthe central control circuit (18) to return the condition of the measuring system (S) into the original condition; (24) designates a level switch which is switched depending upon kind of golf clubs for swinging e.g. either an iron or a wooden club or a putter, and switching of the switch changing a readable sensitive level (Vref) of the zero-cross waveform detecting circuits (15a), (15b), (15c); (18a), (18b), (18c), (18d) respectively designate input terminals; and (18e), (18f), (1sag), (18h), (18i) respectivelydesignate output terminals.

With this structure, when a golf club is swung after selecting the position of the switch (23), movement of a magnetic substance (2") attached to the golf club is detected as zero-cross waveforms which are, in turn, detected by the zero-cross waveform detecting circuits (15a), (15b), (15c).

When an iron or a wooden club is used and if the club is correctly swung, the output level Vf of the zero-cross waveform outputs ea, eb, ec detected by the respective detecting devices (8a), (8b), (8c) exceeds a predetermined readable sensitive level (Vref) for an iron or a wooden club as shown in Figure 11 (a) whereby a predetermined zero-cross detection outputs Ea, Eb, Ec is produced from the waveform processing circuits (16a), (16b), (16c); thus judgement whether the golf club is correctly swung or not is provided from the speaker (20) and the display unit (25).Accordingly, in starting, approaching ortaking back of a swinging play, the zero-cross waveforms ea, eb, ec detected by the detecting devices, Sa, 8b, Sc do not reach the readable sensitive level (Vref) and the detection outputs Ea, Eb, Ec take a state as shown in Figure 11 (b) whereby no instruction is given by the speaker (20) or the display unit (25).

When a putter is used, the level switch (24) is switched to reduce a readable sensitive level (Vref) of the waveform processing circuits (16a), (16b), (1 6c) sufficiently smaller than that utilized when an iron or wooden club is used. In putter play, the speed of movement of the club head (2) is small. Even though output level of the zero-cross waveform is low as shown in Figure 12 (a), detection output reaches the readable sensitive level (Vref) so that a desired zero-cross detection output can be obtained.

The zero-cross waveform outputs ea, eb, ec are also small in approaching ortaking-back play ofthe putter whereby the outputs do not reach the readable sensitive level (Vref) as shown in Figure 12 (b). Thus, no erroneous instruction is given.

Once data are given through the speaker (20) or the display unit (25) by swinging play of the putter or the wooden club, further data can not be received in the central control circuit (18) through the interface circuit (17). When data for the next swing play are desired, the set switch (23) is operated to make the central control circuit (18) release an input prohibiting condition and to supply a signal for returning the data condition of the measurement system S to the original condition through the output terminal (18j) thereby providing condition capable of inputting data. Thus, data of measurement is held unless the set switch is operated and the data can be easily understood.

The speed of the head (2) of a wooden club at striking time is as fast as 50 m/sec. even the club is swung by an amateur player. If a distance of meas urementfor measuring speed of a club head, that is, the distance between the detecting devices (8a) and (8b) in this embodiment, is 5 cm, time required for the club head to pass the distance is 1 milli second (1/1000 sec.) when the speed of the club head just before striking a ball is 50 miser. For measuring direction (angle) of club face (F), it will be necessary to use further smaller unit such as 1/100,000 sec.

In measuring time by using the central control circuit (18) as a microcomputer, processing speed of the microcomputer is limited; for example, several milli second is required for one instruction in a 4 bit microcomputer. Furthermore, at least ten and several instructions are required to perform time meas urementwhereby accuracy of time measurement is lowered and a program for the microcomputer must be complicated.

In the present invention, however, the pulse number of a high-frequency pulse (clock pulse) output is counted in the interface circuit (17) to hold the count numbertemporarily and feed itto the central control circuit (18) after a specific time. This allows a highly accurate time measurement and provides a relatively simple, economical circuit structure.

As described above, a golf training device of the present invention is formed by a detecting device comprising a signal producing part and a detecting part formed in one piece with the signal producing part for detecting variation of signal per unit time caused by mutual interference of the signal producing part and a magnetic substance fitted to at least part of a club head to detect movement of the club head. Accordingly, the moving speed and the moving direction of the golf club can be detected by a golf club head such as an iron club head made of a magnetic material without necessity of requirement of a special device. The signal producing part and the detecting part are formed in one piece to provide a detecting device whereby handling of the golf club is easy and mutual displacement of the detecting part and the signal producing part is eliminated to improve accuracy of the measurement.

Claims

1. A golf training device which includes a golf club which has a club head having a magnetic substance in at least a part of said club head, a detecting device fixed to plural positions of the base to output detecting signals for movement of said club head by detecting variation of said signals per time caused by the movement of said club head, and means for displaying the movement of said club head depending upon said signals from said detecting devices, wherein said detecting device comprises a signal producing partforfeeding signal to the magnetic substance of said club head and a detecting part formed in one piece with said signal producing part to detect variation of signal per time caused by mutual interference of said magnetic substance and said signal producing part.

2. A golf training device according to Claim 1 wherein at least two detecting devices are placed with a predetermined distance in a direction of swinging the golf club.

3. A golftraining device according to Claim 1 wherein at least two detecting devices are placed with a predetermined distance in a direction perpen dicularto that of swinging the golf club.

4. A golf training device according to Claim 1 wherein three detecting devices are provided and two of said devices are placed with a predetermined distance in a direction of swinging the golf club and the remaining detecting device is placed with a predetermined distance to one of said device in a direction perpendicular to that of swinging the golf club.

5. A golftraining device according to Claim 4 wherein said remaining detecting device is placed with a predetermined distance to one of said two detecting devices which is behind of swinging direction and said remaining detecting device being placed in a direction perpendicular to that of swinging the golf club.

6. A golftraining device according to any one of claims 1 to 5 wherein said detecting device comprising said signal producing part and said detecting part in one piece is fitted to recesses formed in predetermined positions in said base.

7. A golftraining device according to any one of Claims 1 to 6 wherein said signal producing part is a magnetic flux producing part for forming magnetic flux in said magnetic substance and said detecting part is a magnetic sensor for detecting variation of magnetic flux per time.

8. A golftraining device according to Claim 7 wherein said magnetic flux producing part and said magnetic sensor are substituted by an exciting coil having dual functions.

9. A golf training device according to any one of Claims 1 to 8 wherein said detecting part comprises a noise shielding sheet formed by bonding or plating non-magnetic metallic material for protecting said detecting part from induction noise.

10. A golftraining device substantially as herein particularly described with reference to the accompanying drawings.