GB2150841A - Golf trainer - Google Patents

Abstract

The golf trainer comprises a mat 43i, a set of magnetic sensors 45a, b, c and d installed in the mat and positioned at predetermined locations relative to an ideal swing path of a golf club head, a golf club selecting key which is settable in accordance with a selected golf club, circuitry for processing detection signals from the sensors to calculate the velocity of the club head and to convert said velocity into data indicative of the carry of a ball hit by said selected club, and a display device 435 for displaying the output of the processing circuitry. <IMAGE>

Description

SPECIFICATION Golf trainer The present invention relates to an electronic golf trainer, and more particularly, to a means for processing a signal indicative of the moving state of a club head.

According to one aspect of this invention, there is provided a golf trainer comprising: a mat; a plurality of sensors installed in said mat for detecting the passage of a swinging golf club head, each sensor producing a detection signal and said sensors being disposed on the centre line of an ideal club head swing orbit; a golf club selecting key which is settable in accordance with a selected with a selected golf club; means for processing said detection signals to calculate the velocity of the golf club head and to convert said velocity into data representing the carry of a ball hit by said selected golf club; and display means for displaying the output of said processing means.

This invention will be described in more detail by way of example with reference to the accompanying drawings in which: Figure lisa perspective view of one embodiment of a golf trainer; according to this invention; Figure 2 is a view illustrating the principles of operation of a simplified sensor of Figure 1; Figure 3 is a view illustrating the arrangement of the simplified sensors; Figure 4 shows waveforms indicative of detected signals from the sensors of Figure 1; Figure 5 is a timing chart for detecting a zero-crossing waveform; Figure 6 is a functional block diagram of the electric circuit used in Figure 1; Figure 7 is a circuit diagram of a device for determining head velocity and face angle; Figure 8 is a flow chart showing how various information is calculated;; Figure 9 is a timing chart for converting detected signal levels from the sensors into times; Figure 10 is a circuit diagram of a device calculating the swing orbit and hitting position; Figure 11 shows curves illustrating the relations between head velocities and ball carry.

Figure 12 is a perspective view of a second embodiment of a golf trainer according to the present invention; Figure 13 is a diagram illustrating the interrelations between the magnetic sensors and a simplified club head; Figure 14 is a block diagram of an electric circuit used in this embodiment; Figure 15 is a timing chart of the output signals; Figure 16 is a perspective view of another embodiment of a golf trainer according to the present invention; Figure 17 is a diagram illustrating the interrelations between simplified magnetic sensors and a simplified club head thereof; Figure 18 is a block diagram of an electric circuit thereof; Figure 19 is an output signal timing chart; Figure 20 is a perspective view of a fourth embodiment of a golf trainer according to the present invention; Figure21 is a perspective view of the magnetic sensor thereof;; Figure 22 is a waveform of a detected signal; Figure 23 is a view showing the waveform of a signal processed in the processing circuit; Figure 24 is a block diagram showing the electric circuitry of a processing circuit; Figure 25 is a perspective view of a further embodiment of a golf trainer according to the present invention; Figure 26 is a block diagram of an electric circuit therefor; Figure 27 is a view illustrative of a club head passing over a magnetic sensor, and of a magnetic sensor; Figure 28 is a voltage value curve of an output signal from the magnetic sensor of Figure 27; Figure 29 is a view illustrative of a club head passing over magnetic sensors in another similar embodiment of the present invention; Figure 30 is a voltage value curve of output signals from the magnetic sensors of Figure 29; Figure 31 is a block diagram of an electric circuit thereof;; Figure 32 is a view illustrating an example of a display; Figure 33 is a perspective view showing another golf trainer of the present invention; Figure 34 is an enlarged view of the principal portion of Figure 33; Figures 35(a) and 35(b)are views illustrative of the principles of detection of the sensors, wherein Figure 35(a) is a longitudinal section of a club head and a sensor and Figure 35(b) is a view illustrative of a zero-crossing voltage waveform generated; Figure 36 is a plan view showing a sensor and a club head, both simplified, in use; Figure 37 is a timing chart of zero-crossing waveforms from the sensors, and detected signals; Figure 38 is a view illustrating the data processing of the detected signals;; Figure 39 is a view illustrative of exemplary blows, wherein parts (a), (b) and (c) show outside-in, straight and inside-out swing paths, respectively; and Figure 40 is a block diagram of a control circuit.

Referring to the drawings, there is shown a golf mat 1 having a lawn-like portion 3 formed on its upper portion, and a golf ball 2 (which is not necessarily required) placed on the lawn-like portion. A sensor case 4 removably installed in this mat has a pair of fork-like protrusions which hold signal generating magnetic sensors 6a, 6b and Sc, Sd, respectively, therein. The sensor case also contains an analog processing circuit 14 which will be described later. Each of these sensors, as seen in Figure 2, consists of a coil 12 wound on a bobbin 11 and a permanent magnet 13 inserted and bonded in the central bore of the bobbin 11. A display unit 9 contains a display device 38, a club selecting key 8 which can be actuated from the outside, and a carrylhead speed change-over key 7.The display device 38 comprises a digital processing circuit 15 (to be described later) for receiving signals from the aforementioned analog processing circuit 14 through a connecting cord 5, an operational circuit 16, and a liquid crystal display device that displays the results of calculations performed by the operational circuit 16 and which consumes a relatively small quantity of electric power. Indicated by numeral 10 is an iron club head, for example.

The principle of operation of the sensors 6a, Sb, Sc and 6d according to the present invention will be described, but for convenience, the description will relate only to the club head 10 and sensor 6b. When the club head 10 passes over the sensor 6b at a certain velocity as shown in Figure 2(a), the flow of magnetic force lines issuing from the permanent magnet 13 will vary. The result is that the quantity of magnetic force lines passing through the coil 12 then varies, resulting in the generation of an induced electromotive force in the coil 12, thus producing a voltage output waveform as shown in Figure 2(b). The voltage value of this waveform increases in proportion to the velocity at which the club head 10 passes over the sensor 6b, and similarly the frequency of the waveform increases in proportion to the velocity.

Further, the voltage value increases as the height at which the club head 10 passes over the sensor 6b is lowered. Sensor outputs ea, eb, ec and ed obtained according to the principles described hereinbefore are processed to derive various information relative to the club swing.

An example of the detection of such information will now be described. Referring first to Figures 3,4 and 5, the velocity of a club head and the face angle thereof are described. If the club head 10 moves in a direction indicated by an arrow as it is swung as shown in Figure 3, then the outputs from the four sensors will be the signals ea, eb, ec and ed shown in Figure 4, which in turn are converted to digital signals Zb, Zd and Zc shown in Figure 5 to obtain the periods of time Ts and To it takes for the club head 10 to pass the interval between the sensors 6b and 6d and that between the sensors 6d and 6c, respectively.

A control circuit 30 of the present invention utilizing the principle of detection described hereinabove will now be described in detail. Referring to Figure 7, indicated by numerals 17b, 17d and 17c are amplifiers I which amplify the respective minute detected signals from the sensors 6b, 6d and 6c by a given factor. SN discriminators 18b, 18d and 18c discriminate only those necessary signals indicative of the swinging state from among the output signals including noise and the detailed signals.Zero-crossing detectors 19b, 19d and 1 9c further amplify the signals eb, ed and Q, respectively, and select points of induced electromotive voltage which cross the reference zero voltage, at which points maximum lines of magnetic force are developed, in order to obtain signals from a fixed position on the sole, that is, the flattened bottom of the club head 10, which may take various shapes. Then, the zero-crossing detectors produce signals Zb, Zd and Zc, each in the form of a pulse falling at the zero-crossing point.Indicated at numeral 20 is a counter circuit I which measures the time Ts from the pulse signals Zb and Zd, while a counter circuit 21 measures the time To from the pulse signals Zd and Zc. A club face direction judgment circuit 22 judges the direction at which the club face forms an angle from the pulse signals Zd and Z,. A club data memory 23 stores predetermined data individually set for various clubs. A club data selecting portion 24 is operated by the memory in accordance with the flow chart shown in Figure 8, and selects club data in response to the club desired at that time.A velocity calculator 25 calculates the velocity of that club head based on the time Ts from the first counter circuit 20. Aface angle calcuator 26 calculates the face angle at the moment of impact based on the time To from a counter circuit 21 and the time Ts from the counter circuit 20. A face angle judging and calculating unit 27 judges whether the data from the face angle calculator 26 represents an open club face state or a closed state based on the signal from the club face angle judging circuit 22. Atemporary storage unit 28 temporarily stores data calculated by the velocity calculator 25, face angle calculator 26 and face angle judging and calculating unit 27.

A control unit 29 controls operations on the flow chart shown in Figure 8 in accordance with a predetermined format and also stores a program for storing and displaying data concerning a ball carry calculation and a distance-from-target calculation and various data on hitting positions, club head orbits and so forth. The control unit 29 further stores a program for controlling data processing and calculation in one embodiment of the present invention. The contents of the storage unit 28 are displayed on a display portion 33. The aforementioned velocity calculator 25, face angle calculator 26, face angle judging and calculating unit 27, storage unit 28, control unit 29, club data memory 23 and club data selecting portion 24 may be included in a central processing unit 31 which consists of a microcomputer A, for example. A timing control unit 32 generates timing signals for controlling the microcomputer and counter circuits 20 and 21. The aforementioned zero-crossing detectors 19b, 19e and 19d, counter circuits 20 and 21 and judging circuit 22 make up a zero-crossing discrimination circuit 51 acting as a zero-crossing discriminating means.

Referring next to Figures 3,4 and 9, the detections of the orbit or blow of the club head and the impact position are described. When the club head 10 moves in the direction indicated by the arrow as it is swung as shown in Figure 3, the sensors produce signals ea, eb, ec and ed as shown in Figure 4, and these signals have maximum output values Ea, Eb, Ec and Ed, respectively, as shown in Figure 4. Then, these signals are converted to digital signals Ab, Aa, Ac and Ad as shown in Figure 9, and the output voltage difference between the sensors 6b and 6a and between the sensors 6d and Sc are detected.

A control circuit 34 which operates using the detection principle described hereinabove and acts as a processing means will be described in detail. Referring to Figure 10, amplifiers 17b, 17a, 17c and 17d amplify signals from the sensors 6b, 6a, 6d and 6c, respectively, by a given factor to produce outputs EB, EA, EC and ED, which in turn are applied to respective low pass filters (abbreviated as LPF hereinafter) 35b, 35a, 35d and 35c to filter out the high frequency components of the noise induced in the sensors which include low and high frequency components. The cut-off frequency of the LPFs is set to a frequency equivalent to the highest possible velocity, for example 60 misec, of a swinging club head, which value is statistically derived.Peak holding circuits 36b, 36a, 36e and 36d hold the outputs signals EB, EA, EC and ED from the LPFs at a constant value, and a multiplexer 38 (abbreviated MPX hereinafter) converts outputs from the peak holding circuits into serial data in response to instructions from a microcomputer 42 (described later) containing a multiplexer control unit 43 to produce output signals EB, EA, EC and ED, which are converted in turn to digital signals Tb, Ta, Tc and Td in succession by an analog-to-digital (AID) converter 40. A reference timing circuit 41 sets the reference timing for the analog-to-digital conversions.

A microcomputer 42 acting as a central processing unit receives an output from the A/D converter 40 and produces signals which are applied to the peak holding circuits 36b, 36a, 36e and 36d via the MPX 38 to reset the peak holding circuits. Processing by the microcomputer 42 is initiated by a start signal from a zero-crossing judging flip-flop circuit (abbreviated as ZJFF hereinafter) 37, which receives an input from a zero-crossing detecting circuit 20 coupled to LPF 35b. The microcomputer calculates the relative positions of the club head 10 and the sensors 6b, 6a and of the club head 10 and the sensors 6d, 6e based on clock pulses from a clock pulse oscillator circuit 39. The microcomputers 42 and 31 transfer the result of their calculations to each other.In the microcomputer 42, reference numeral 44 represents an MPX input port selecting unit for designating the output of the peak holding circuit 36a-36d which is to be subjected to AID conversion. The operation program for the microcomputer is contained in a memory unit 46. Output data to be displayed is delivered to a display unit 31 by way of an LCD drive buffer 45 for controlling the display operation.

The structure described hereinabove permits calculation of the following information relative to a club swing: (1) the velocity of the club head, (2) the carry of the ball, (3) the face angle at the moment of impact, (d) the direction in which a ball is hit, (5) the orbit of the club head, (6) the impact position, (7) the distance from a target to the spot at which the ball landed, (8) a judgment as to whether the ball fell within a "fairway".

With respect to the club head velocity V of item (1) above, this may be approximately calculated by the following equation: V= L/Ts With respect to carry of the ball of item (2) above, head velocities and the resultant carry of a ball are statistically processed for each kind of club to obtain curves 104, etc. as shown in Figure 11. Then, each curve is resolved into a combination of a linear formula and a quadratic formula. Finally, the carry C of the ball is approximately calculated using this composite formula.

With respect to the face angle of item (3), this parameter is approximately calculated by the following equation: a = Tan-1 [(L x To) / (D x T5)] With respect to the direction 6 in which the ball is directed (item (4)), this is calculated by vector transformation in a manner in which a closer approximation is made than with the face angle a and head velocity V. Further, the calculated angle 6 can be divided into sections such as 0-4", 5-9", 10-19" and 20 or more for display purposes to roughly indicate the direction.

With respect to the orbit of the club head (item (5)) a straight orbit is approximately calculated by the following relations: Era/3 < I E5 - Ebi, Web/3~ I EaEbl, K (constant) < E2 and K < Eb.

Then, outside orbits and inside orbits can be calculated based on the aforesaid data taking detected data into consideration.

With respect to the hitting or impact position, toe, sweet and heel positions are approximately calculated in the same manner as in (5) above by the following relations: Ec/3 ' ' Ec - Ed, Ed/3 =' r Ec - Ed, K < Ec and K < Ed- With respect to the distance S from a target as described above, approximately values can be calculated using the following equation: S = C x Sina With respect to the judgment as to whether the swing was successful, if the velocity V of club head is higher than a predetermined constant K, for example 60 misec, then the swing will approximately be judged to be unsuccessful. On the other hand, if the velocity is slower than K, it will be judged to be normal.

Finally, with respect to the judgment of item (9) above, if the distance S from the target is larger than a predetermined constant I, for example 40 m, then the swing will approximately be judged to be abnormal.

On the other hand, if the distance S is shorter than the constant I, the swing will be judged to be normal.

Referring to the flow chart shown in Figure 8, the operations for calculating the various parameters are described. First, the calculation memory is initialized (S1), and then it is checked whether a start signal ST from the sensor 6b is detected (S2). If this signal is not detected, it is checked whether the club selecting key 8 has been depressed to select a desired club or the carrylhead speed switchover key 7 has been depressed to select a desired display (S3).If either key is actuated, then club data is selectively fetched from the club data memory 23, and data on the carryíhead speed switchover is applied to the display portion 33, and at the same time the selected club data is applied to the carry calculator (not shown) and stored (S4). if no key is depressed in process step S3, then the flow returns to process step S2 with the club data having been initialized in S1 and the carry/head speed change-over data remains unchanged. If the start signal ST is detected in the process step S2, then it is checked whether signals from the sensors Sc and 6d are detected (S5). If not (NO), the flow returns to process step S2.If so (YES), the flow proceeds to process steps S6 and S7 so as to permit the microcomputers 31 and 42 to process the respective information. The microcomputer 42 receives detected signal level and time data Ta, Tb, Tc and Td to calculate the swing orbit and the hitting position (S6, S8), and then judges whether the microcomputer 31 has requested a transfer of the results of these calculations (S9). If there exists such a request, then the calculated data is transferred (S10), and thereafter the calculation memory is cleared (ski 1), and then the flow returns to step S2.

The microcomputer 31 receives time data Ts and To from the sensors to calculate various information (S7, S12); and then transfers a data request instruction to receive information in process step S8 (S13). It then judges whether data from S10 is received (S14), and then this various information is caused to enter the display portion and the memory (S15). The flow then returns to S2, thus completing the flow chart.

The aforementioned electric circuitry can be classified into four principal parts: an analog processing circuit 14, a digital processing circuit 15, an operational circuit 16 and a display portion 33, as shown in Figure 6. A complementary MOS IC consuming a relatively small quantity of electric power is used in the digital processing circuit 15, and liquid crystal devices, which also consume a relatively small quantity of electric power are used in the display portion 33. Further, the operational circuit 16 uses a microcomputer consuming little electricity and, therefore, the whole apparatus consumes very little power. As a result, the apparatus can be used outdoors for a long period of time while supplied with electric power from a battery (not shown).Furthermore, the analog processing circuit 14 uses an IC which consumes little electricity, or the whole circuit 14 is so formed that it consumes less electricity to enhance the aforementioned energy savings.

In the operation of the structure described hereinbefore, the club selecting key 8 (which is not necessarily required) is depressed by a user to select the golf club used. If she swings thereafter, various information relative to the swing will then be calculated and displayed.

Another embodiment of the invention will now be described, referring to drawing Figures 12-15. A display device 221 holds a display portion 212 (described later), a processing circuit and soon therein. Awhile line 223 is drawn on a base mat 221 along the swinging orbit, and a tee 224 is placed on the mat, in which magnetic sensors 21 a and 21 b are buried in position. The magntic sensors 21 a and 21 bare disposed at an interval L (for example, cm) in the swing orbit of the club head 213. Amplifier circuits 22a and 22h amplify detected signals ea and eb from the respective magnetic sensors 21 a and 21b by a predetermined factor and eliminate radio-frequency induced noise to produce amplified output signals Ea and Eb, respectively.

Zero-crossing discrimination circuits 23a and 23b separate the zero-crossing points of the detected, amplified signals at which the magnetic flux in said magnetic sensors shows the greatest change, and the detected signals are converted to pulse signals Za and Zb which rise at a noise level cut voltage V produced from a reference voltage generator circuit 226 and fall at the respective zero-crossing points.

Flip-flop circuits 23a and 24b receive points from respective zero-crossing discrimination circuits 23a and 23b and produce signals Fa and Fb which are set at the fall points, respectively. An exclusive-OR circuit 27 receives outputs from the flip-flop circuits 24a and 24b and produces a signal St having a pulse width equal to the time Tv it takes for the club head to pass through the interval between the magnetic sensors 21 a and 21 b. An AND circuit 28 ANDS the signal St and a given high frequency clock pulse (for example, 400 kHz) from an oscillation circuit 29, and the resultant output is applied to a high speed binary counter 210 for counting the number of pulses.An operational circuit 211 consisting of a microprocessor (for example, an PMD-7502G) calculates the speed of the club head from the interval L between the magnetic sensors and the time T,, resulting from the output from the counter 210 based on a calculation formula, V = L/Tv and produces the result as an output. A display portion 212 receives the output from the operational circuit 211 and displays the speed per second in meters.

Thus, when a golfer swings while standing before the trainer, the device reads out the speed of the swinging club head precisely and displays it on the display portion.

A third embodiment of the invention will now be described with reference to Figures 16-17. Referring to the drawings, a display device 321 similar to that of the previous embodiment holds a display portion 312 and processing electronics. A base mat 322 contains magnetic sensors 31 a, 31 band 31e buried in position.

The magnetic sensors 31a and 31 bare disposed at an interval L (for example, cm) in the swing orbit of the club head, and the sensor 31e is disposed at right angles to the magnetic sensor 31 bat a distance D (for example 4 cm) from the sensor 31 b. Amplifier circuits 32a, 32b and 32c amplify detected signals ea, eb and ec from their respective magnetic sensors 31 a, 31 b, 31c by a predetermined factor and eliminates noise to produce amplified output signals Ea, Eb and Ec, respectively.Zero-crossing discrimination circuits 33a, 33b and 33c separate the zero-crossing points of the detected, amplified signals at which magnetic flux in said magnetic sensors shows the greatest change, and the detected signals are converted to pulse signals Za, Zb and Zc which rise at a noise level cut voltage V produced from a reference voltage generator circuit 306 and fall at their respective zero-crossing points.

Flip-flop circuits 34a, 34b and 34c receive outputs from the respective zero-crossing discrimination circuits 33a, 33b and 33c and produce signals Fa, Fb and Fcwhich are set at the fall points, respectively. An exclusive-OR circuit 37a receives outputs from the flip-flop circuits 34a and 34b and produces a signal St having a pulse width equal to the time Tv it takes for the club head to pass through the interval between the magnetic sensors 31 a and 31 b. The arrangement described thus far is substantially similar to that of the second embodiment described above.

An exclusive-OR circuit 7b receives outputs from the flip-flop circuits 34a and 34c and produces a signal Dt having pulse width equal to the time To it takes for the club head to pass through the interval between the magnetic sensors 31 b and 31c. An AND circuit 8a ANDs the signal Stand a given high frequency clock pulse (for example, 400 KHz) from an oscillation circuit 309, and the resultant output is applied to a high speed binary counter 31 0a for counting the number of pulses.Similarly, an AND circuit 38b ANDs the signal Dt and the high frequency clock pulse from the oscillation circuit 309, and the resultant output is applied to a high speed binary counter 310b for counting the number of pulses. An operational circuit 311 consisting of a microprocessor (for example, an MPD-7502G) calculates the face angle of the club head from the distances D and L between the magnetic sensors 31 a, 31 band 31c and from the periods of time resulting from the outputs and from the counters 10a and 10b based on a calculation formula:

and produces the result as an output. The display portion 212 receives the output from the operational circuits and displays the result in degrees.

Thus, when a golfer swings while standing before the trainer of this embodiment, the device reads out the face angle of the swinging club head precisely and displays it on the display portion.

A fourth embodiment of the invention will now be described with reference to Figures 20-24. A base mat 431 has a lawn-like portions 433 and a line on the center line of the orbit of a club head in an ideal swing.

Magnetic sensors 45a, 45b, 45c and 45d are buried in position along the ideal orbit of the club head. A display device 435 includes a circuit portion (described later) and a display portion 436, and output signals from the magnetic sensors are applied to the display device through a connecting line 437. Each of the magnetic sensors 45a, 45b, 45c and 45d consist of a coil 44 wound on a bobbin 43, a permanent magnet 42 fixedly inserted in a central bore in the bobbin 43, and a shielding membrane 41 shielding these elements.

Referring next to Figures 2 and 22, detection of the moving state of the club head in this embodiment will be described.

When the club head passes over the magnetic sensor 45a at a certain velocity, the quantity of magnetic flux issuing from the permanent magnet 42 and passing through the coil 44 changes and induced electromotive force e is generated in the coil 44. The waveform of the electromotive force e changes so that its crest value and frequency vary in proportion to the velocity of the passing club head, and the larger the interval between the magnetic sensor 45a and club head, the smaller the crest value will be.

Referring to Figures 23 and 24, an example in which only a necessary signal is discriminated relative to the induced noise and the detection signal indicative of the swinging state will be described.

When the club head moves in a direction indicated by an arrow (Figure 2) upon swinging, the output from the sensor 45a can be represented by a signal e1 which includes extraneously induced noise, as shown in Figure 23. This induced noise is eliminated by the shield 41 considerably, but it remains to some extent, and is required to be removed. In Figure 24, an amplifier circuit I which amplifies the minute signal from the sensor 5a by a predetermined factor is indicated by numeral 46, and resistors 414a and 415b define the aforementioned factor.A low-pass filter (abbreviated LPF hereinafter) 46 removes high frequency noise components from the output signal e0 which includes both noise and the detected signal indicative of the swinging state, and the filter acts as a means for amplifying the signal from which the noise has been removed by a predetermined factor, which factor is in turn defined by resistors 415 and 416. The range of high frequency components to be removed is determined by a combination of a resistor 416 and a capacitor 417. An amplifier circuit 48 amplifies the signal e0 by a predetermined factor, determined by resistors 418 and 419, so as to facilitate removal of low frequency noise components from the output signal E from the LPF circuit 47.A comparator circuit 49 which receives the output signal E0 from the amplifier circuit 48 and a reference voltage D (Vref) from a reference voltage generator (VG) circuit and compares their levels.

Similarly, a comparator circuit 410 compares the levels of the output signal E0 and Vref. A flip-flop (FF) circuit 416 operates by receiving the output signal ZA from the comparator circuit 49 and the output signal ZB from the comparator circuit 410, which with 49, FF circuit 416 and VG circuit 412 operate as a low frequency component level lowering means. A peak holding circuit 411 peak-holds the maximum voltage value Ep of the output signal E from the LPF circuit 47, and the maximum voltage value Ep from the peak holding circuit 11 is converted to digital form by an AID converter circuit 421. A central processing unit (CPU) 13 calculates a signal Tp from the output signal Ap of the A/D converter circuit 421 and arithmetically derives various information based on the signal Z from the FF circuit 16 and other inputs as shown.The VG circuit 412 generates various reference voltages, such as VrefB, VrefD, etc. Also included in this processing circuit are a display portion 438, the aforementioned amplifier circuit 46 indicated by numeral 439, LPF circuit 47, amplifier circuit 48, comparator circuit 49, comparator circuit 410, peak holding circuit 411, AID converter circuit 421 and FF circuit 416.

The amplification factor of the amplifier circuit 46, the cut-off frequency of the LPF circuit 47, the amplification factor of the amplifier circuit 48 and the reference voltage constants of the VG circuit 412 will now be described in more detail.

The conditions under which the club head passes over the sensor 45a can be considered as follows to determine the constants: (1) the height at which the club head always hits the golf ball, (2) the velocity of the club head which causes the golf ball-to fly or roll, (3) the velocity of the club head reasonably attainable, and (4) orbits of the club head and hitting positions which permit no hitting of the ball.

First, with respect to (1), the interrelation between the club head and the sensor has a close relationship with the velocity of the club head referred to in (2) above. The circuit is designed so that the detected signal voltage from the sensor 45a when the club head narrowly hits a golf ball at its minimum velocity at the highest elevation, and the detected signal voltage from the sensor 45a when the club head hits a ball and almost rubs the mat at its maximum velocity at the lowest elevation are both greater than the induced noise.

Further, the amplification factor of the amplifier circuit 46 is so determined that no saturation will occur when the detected signal voltages are amplified in the circuit.

With respect to (3), a head velocity, for example, 60 m/sec, is calculated in terms of time T of the detected signal e from the sensor 45a, and this time is converted to a frequency employing the following relation: f=1/T Then, a cut-off frequency c for the higher components is calculated, and then LPF circuit 47 is designed so that it has a constant equivalent to this cut-off frequency.

Finally, with respect to (4), in order to calculate the orbit and hitting position, the maximum voltage value Ep from, the LPF circuit 47 should be detected certainly. For example, in relation to the relation (1) and (2), when the head velocity is less than a certain value, such as 10 m/sec, the signal cannot be sufficiently amplified and, therefore, the maximum voltage value Ep from the LPF circuit is made ineffective. The amplifier circuit 48 acts to detect a zero-crossing point, and the amplification factor is set to a relatively high value in order to determine the zero-crossing point more clearly. As a result, almost all amplified signals will saturate.

Under these conditions, the VG circuit 412 is constructed so that it generates reference voltage, VrefB and VrefC so set that the circuit may stably operate in various circumstances, V,efD is set so that it is considerably greater than the amplified low frequency noise, and VrefE is set to a voltage value for deriving the zero-crossing point b, for example, 0 volts of the detected signal from the sensor 45a.

In the description above, only the magnetic sensor 45a was described in detail, but the magnetic sensors 45b and 45d function in the same manner as the sensor 45a. The magnetic sensor 45c operates simpiy in association with the peak holding operation in the processing circuit 439. Also sensors consisting of a coil having a permanent magnet in the center thereof were referred to, but other magnetic sensors, such as search coil or Hall effect elements, may be used instead. Further the number of the elements is not limited to four. It is also noted that the aforementioned high frequency filtering means and low frequency level lowering means can be replaced by other means which attain the same purposes.

A further embodiment of the present invention will now be described with reference to Figures 25-32.

Referring to the drawings, there are shown the head 51 and face 51 sofa golf club. The golf trainer has a base 52 constructed similarly to that of previous embodiments. Magnetic sensor 56, buried along the center line R of the swing orbit, consists of a permanent magnet 562 and 563 buried in a resin 564 of, for example, epoxy, within a case 561 of resin. A display device 58 includes an amplifier circuit 520 for amplifying the detection signal from the magnetic sensor 56 resulting from the change in magnetic flux. Also included in the display device 58, which is connected to the magnetic sensor 56 through a signal line 59, are a processing circuit 524 for processing the output from the amplifier circuit and a display portion 511 consisting of liquid crystal display devices for displaying the processing result.

In the operation of this golf trainer, when the club head 51 passes over the magnetic sensor 56, the voltage value of the output signal from the magnetic sensor 56 exhibits a maximum in the event tht the center 512 of the club head 51, which lies approximately in the center of gravity and concurrently approximately in the center of the sweet spot area, passes just above the magnetic sensor 56. The value decreases as the displacement toward the inside (-4) or outside (+t) increases, as shown in Figure 27 and 28.Further, an ordinary golfer may swing so that the club head 1 passes above the base 2 at approximately a constant elevation, and, therefore, by presetting the maximum outputs when the head passes just above the magnetic sensor 56 according to the kind of club head used, assuming the area of displacements S1 - S2 to be the sweet spot area to store in a memory 525 of the processing circuits 524, and by comparing an amplified signal from the magnetic sensor 56 upon swinging with a corresponding preset value in a comparison portion 526 of the processing circuit 524, it can easily be displayed whether the ball was hit by the sweet spot area of the club or not.

A modification of the foregoing is shown in Figure 29, where two magnetic sensors 56 and 57 are disposed on opposite sides of the center line R of the swing orbit within the orbit at a distance D (actual club heads have a width W of some 8 cm on the average, but herein the distance D is assumed to be 2 cm, shorter than the above value) from the center line, thus permitting the user to know whether his swing orbit is displayed toward the inside (-t) or outside (+e).

In Figures 29-32, reference numerals 51,56,57 and 515 are used in the same manner as in the above embodiment, and numerals 513 and 514 indicate voltage value curves V1 and V2 of the output signals from the magnetic sensors 56 and 57, respectively.

Detected outputs resulting from the structure described above are processed by an electric circuit shown in Figure 31. Specifically, as the club head 51 passes over the magnetic sensors 56 and 57, these sensors produce signal voltage values V1 and V2 which are applied to amplifier circuits 521 and 522, which in turn amplify the values by a predetermined factor to produce outputs V1 and V2. A processor circuit 523 for receiving these outputs compares the magnitudes of the outputs to graphically display "outside", "sweet spot" or "inside" or the like on the display portion 511.

It is said generally that the sweet spot has an area having a diameter of some 20 mm, but the area is affected by differing club heads and golf balls. Accordingly, it is necessary to assume an area in the range of 10 mm to 30 mm in diameter.

As an example, if the sweet spot ranges from S1 to S2 on the abscissa in Figure 30, then the output voltage value from the magnetic sensors at the S1 is as follows: V1 = 2V2 similarly, the value at the S2 point is as follows: V2=2V1 Therefore, the following relation holds between the S1 point and the 0 point: 2 V2 'V1 ~ V2 and 2 V1 ~ V2 ~ V1 holds between the S2 point and the 0 point. Thus, it is possible to identify the aforementioned sweet spot.

Also in this example, if V1 > 2 V2 and V2 > 2 V1 occur, these are represented as "outside" and "inside", respectively. An example of the display is shown in Figure 8.

It is noted that in this embodiment, an impact position of a ball (which is not required in actual fact) with the face of the club head is displayed by comparing the magnitude of voltage values produced from two magnetic sensors. However, the present invention is not limited to a comparison of the magnitudes of voltage values, and a comparison of the magnitudes of current values, a comparison of phase shifts etc., may be employed.

A final embodiment of the present invention will hereinafter be described. Referring to Figures 33-40, there is shown the body of a golf trainer similar to that of previous examples and having a control circuit614 therein. Also shown as a display portion 62, a club selecting key 67, a base 63, such as a mat, connected with the body 61 through a cord 64, and a golf club head. Sensors 69,610,611 and 612 consist of magnets 69b, SlOb, 611 and 612b and coils 69a,610a,611a, and 612b wound with a predetermined number of turns on these magnets, respectively, as is shown in Figure 34. The sensors 611 and 612, forming a pair, are disposed on an ideal swing line R and on opposite sides of the line R spaced by the same distance P/2.The sensors 69, 610, also forming a pair, are disposed at a given distance L (for example 50 mm) from the pair of sensors 612 and 611, respectively, further away from the tee.

When the club head passes over the sensor 610, for example, at a certain velocity (for example, the hitting velocity) as shown in Figure 35 (a), an output having a voltage waveform as shown in Figure 35 (b) is produced by the sensor 610. Just when the center of the sensor 610 overlaps the center of the club head, the voltage drops to zero. The zero-crossing waveform crest value is proportional to the passing velocity.

By utilizing the above principle, various conditions necessary for the judgment of the appropriateness of club swings can be detected as follows: In the detection of six conditions: (1) swing velocity, (2) orientation of the club face, (3) carry of the ball, (4) impact point with the club face, (5) hit, and (6) distance from a desired target, if the club head passes just over the sensor 610 or near this sensor, then a voltage having a zero-crossing waveform E1 as shown in Figure 37 will be induced in the sensor 610. If the club head passes just over the sensor 69 or near this sensor, then a voltage having a zero-crossing waveform as shown atE2 will be induced in the sensor 69.If the club head 13 passes just over the sensor 611 or near this sensor, a voltage having a waveform as shown atE3 will be induced in the sensor 611, and finally, if the club head passes just over the sensor 612 or near this sensor, a voltage having a form as shown atE4 will be induced in the sensor 612.

Accordingly, if the zero-crossing waveforms from the sensors 69,610, 611 and 612 are detected from the respective zero-crossing moments to the respective terminations of the waveforms, detection outputs as shown at Ea, Eb, Ec and Ed are obtained, and these outputs can be used to judge the appropriateness of the swings.

With respect to the swing velocity of item (1) above, when a detected output Ea occurs, a pulse is produced and applied to the set input of a flip-flop, and when a detected output Ec develops, a pulse is produced and applied to the reset input of the flip-flop, resulting in a pulse output for measuring the velocity as shown at Ef.

This pulse output Ef is then ANDed with a clock pulse from a high frequency oscillator 621 to produce a clock signal as shown at E,. The clock frequency of the signal En is counted by a binary counter to derive the time difference Tv between detected outputs Ea and Ec. Then, the time difference Tv is divided by the distance L between the sensors 610 and 611 to derive the swing velocity.

With respect to the orientation of the club face (item (2) above), a pulse is produced when the detected output Ea is generated from the sensor 610, and this pulse is applied to the set inputs of two flip-flops. One of the flip-flops produces a pulse when the sensor 611 generates the detected output Ec, and this pulse is used as a reset input therefor to obtain an output as shown in Figure 6 at Ep, while the other produces a pulse when the sensor 612 generates output Ed, and this pulse is used as its reset input to derive an output as shown at Eg. Then, a pulse output Er, for measurement, which is proportional to the time difference between the two detected outputs Ep and Eg is obtained.Then, the pulse Er is ANDed with the clock pulse from the high frequency oscillator 621 in the same way as in the velocity detection to produce a clock output signal as shown at Em. Thereafter, the clock frequency of this signal is counted by a binary counter to obtain the time difference Tc, and an inclination or orientation angle a can be obtained by the use of this time difference, the interval L between the sensors 610 and 611 and the interval P between the sensors 611 and 612.

With respect to the carry of the ball, or the distance traveled by the ball, of item (3) above, club head velocity data is preset for each kind of club and is stored in CPU 618, and specific data is selected by actuation of the club selecting key 67 to calculate the carry using this data and the aforementioned head velocity.

With the respect to impact point of the club face (item (4) above), the peak values of the zero-crossing voltage waveforms from the sensors 611 and 612 are compared, and if the lower peak is not smaller than the higher peak by a certain factor (for example, 75 %), then the center of the club head 13 is judged to have passed yenerally above the ideal straight line R at the moment of impact. On the other hand, if the lower peak is smaller than the higher peak by the above factor, the club can be judged to have shifted toward the sensor producing the higher peak.

With respect to the detection of item (5) above, the blow can be judged by the specific one of the sensors 69, 610, 611 and 612 that detects the club head. Regarding an intermediate position between the sensors 69 and 610, the voltage values of zero-crossing waveforms of these sensors are compared in the same manner as the impact point with the club face of item (4) above was calculated. As a result, the center of the club head can be located between the sensors 69 and 610, and the direction of the swing can be judged by comparing this data and the aforementioned data from the sensors 611 and 612.

Finally, with respect to the distance from a desired target (item (6)), this can be calculated from the carry of the ball, the orientation a of the club face and the direction of the swing.

The control circuit 614 of the present embodiment utilizing the detection principles described above will now be described in detail. Referring to Figure 40, zero-crossing detection circuits 615a, 615b, 615e and 615d detect respective zero-crossing waveforms from the aforementioned sensors 69, 610, 611 and 612.

Waveform processing circuits 616a, 616b and 616c convert the respective zero-crossing waveforms into predetermined detected waveforms which are produced as detected outputs Ea, Eb and Ec as shown in Figure 37.

An interface circuit 617 converts the output signals from the waveform processing circuits into other signal forms which can be processed by the CPU 618. The interface circuit incorporates the aforementioned binary counters (not shown) for counting the number of clock pulses contained in the clock signals En and Em. Count outputs from the binary counters are held for a certain period of time, and are then applied to the CPU 18.

The high frequency oscillation circuit 621 supplies high frequency pulses to the interface circuit 617.

Peak holding circuits 632a, S32b, S32c and 632d detect the peak values of the output voltages of the zero-crossing waveforms and hold them, and an interface circuit 633 reads out the peak values from the peak holding circuits and judges the aforementioned impact point and hit (items (4) and (5) above).

The CPU 618, which is a microcomputer, receives data from the aforementioned interface circuits 617 and 633 and processes the data for judging or calculating various swing parameters.

A display device 62 displays the result of the judgment or calculation of the CPU 618, and a loudspeaker 620 may read aloud such result. A reset switch 623 releases the state inhibiting data entry and resets the control circuit 614 to its initial condition. The club selecting key 67 is intended for selecting a specific data set from various club data determined from the reaction of a golf ball relative to various kinds of golf clubs.

In the operation of the structure thus described, the reset switch 623 is actuated, and then a swing is taken.

The moving state of the golf club is detected by the sensors 69,610,611 and 612, and the zero-crossing detection circuits 615a, 61 5b, 61 5e and 615d receiving the detected signals produce zero-crossing waveforms, which in turn are processed by either the waveform processing circuits 616a,616b and 616d or peak holding circuits 632a, 532b, 632c and 632d, and the signals are then applied to the loudspeaker 620 and/or display portions 62 through the interface circuits 627 and 633 and CPU 618 for displaying and/or reading aloud the signals as various information relative to the swing.

Thus, in accordance with the present invention, a very advantageous golf trainer can be provided which may include various processing means for performing processing based on detected signals from one or more sensors detecting the moving state of a club head, noise elimination means, and zero-crossing discrimination means for detecting points crossing a predetermined voltage based on the detected signals from the sensors, thereby permitting a precise, rapid and objective display of various information concerning a swing of a golf club.

Claims (1)

1. A golf trainer comprising: a mat; a plurality of sensors installed in said mat for detecting the passage of a swinging golf club head, each sensor producing a detection signal and said sensors being disposed on the centre line of an ideal club head swing orbit; a golf club selecting key which is settable in accordance with a selected golf club; means for processing said detection signals to calculate the velocity of the golf club head and to convert said velocity into data representing the carry of a ball hit by said selected golf club; and display means for displaying the output of said processing means.