Abstract:
Teaching golf clubs that signal a golf ball/club face impact location comprising a putter having a head with an elastomer or thin hard material face cover protecting piezoelectric sensors electrically connected to an electrical circuit provided with light emitting diodes (LEDs) arranged to visually indicate the impact location, the electrical circuit printed on a circuit board tightly inserted into a golf club head cavity or embedded in a plastic matrix and an iron and a “wood” golf clubs having elastomer or thin hard materials coated on plates inserted into piezoelectric sensors electrically connected to an electrical circuit on a circuit board inserted into a club head cavity or embedded in a plastic matrix with LEDs indicating a golf ball/club face impact location. Each teaching club has a matching Profession Golf Association approved club for golf course play.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to teaching golf clubs and matching Professional Golf Association (PGA) approved golf clubs, more specifically teaching and matching professional putters, irons and “woods”, so that the teaching clubs provide user information concerning a point of club face impact on a golf ball thereby helping the user to develop a smooth, consistent golf swing and the professional clubs provide a means for putting the information learned in actual golf course play. The teaching golf clubs utilize club head self contained visual display means for imparting club/ball impact information. The user trains using the teaching golf clubs and transfers to the professional clubs for golf course play. It should be noted that a “wood” is no longer constructed of wood but can be made of metal alloys, high impact plastics or any number of synthetic materials. 
     2. Discussion of the Prior Art 
     In order to maintain or improve a golf game, a golfer must develop an efficient golf swing where the golf ball is impacted on the club center or “sweet spot”. This impact transfers maximum energy from the club head to the ball and allows the ball to travel on a trajectory intended by the user. Whether or not the ball impacts on the club center or “sweet spot” is not always obvious to the user. When the user has a means for knowing a point of impact, the user can quickly made constructive changes to improve his/her golf swing. After a golfer consistently makes ball contact with the golf club face “sweet spot” as indicated by a visual signal, the golfer gains confidence and attains “muscle memory” that eventually allows the golfer to automatically swing correctly. Then the golfer is ready to use a PGA approved golf club without ball impact information but having substantially identical weight, balance, shape and size as the teaching club on a regulation golf course. 
     The following relevant golf club training devices are the result of a customary prior art search: U.S. Pat. No. 4,898,389 discloses a training golf club comprising a clip on carrier unit have a transducer array overlying a golf club face and a monitor display sitting on a golf club top surface. A ball impact generates a voltage proportional to a force exerted on a transducer which is analyzed to indicate the point of impact. In the present invention, an analysis of voltage generated by an impact on a club face sensor is not dependent on the amount of impact force. In addition, all detection components are internal where component vibration and movements on ball impact are almost non existent. In a clip on arrangement, vibration and movement on ball impact are likely to effect the accuracy and precision of transmitted monitor information. 
     U.S. Pat. No. 4,940,236 describes a golf club built in swing analyzing device that utilizes a club face transducer to produce signals sent to a club grip cap LCD indicator to inform the user of the total yardage traveled by an impacted ball. Since output information differs from the present invention output, impact analyzing electrical circuitry is also different. 
     In U.S. Pat. No. 5,209,583 a user notification device informs the user of a trajectory followed by a movable object such as a golf ball after an instrumented sporting device such as a golf club strikes the golf ball. Here, again, output information and electrical circuitry differ from the present invention. 
     In U.S. Pat. No. 5,709,610 the present inventor discloses a spring controlled push button electrical contact system used to transmit information concerning golf ball impact on a golf club face by means of LED signals. The present invention provides a different impact sensor means along with new circuitry for detecting golf ball impact location on a club face. 
     In addition, U.S. Pat. Nos. 3,182,508, 5,230,512 and 5,441,269 along with U.S. Pat. No. 5,792,001 disclose golf club training devices that notify the user of the magnitude of force of a golf ball impact, of a path of a club swing and of any abnormal acceleration of deceleration of a putter club head, respectively. 
     None of the relevant prior art inventions disclose a combination of pressure sensors embedded in a golf club face that stimulate LED indicators to disclose golf ball/club face impact location for use in a teaching setting along with a matching professional golf club for use in a playing setting on a regulation golf course. 
     The primary objective of the present invention is to provide a teaching golf club having self contained golf ball impact sensor means in order to instantly indicate visually to the user ball impact location and, then, to provide the user with an identically balanced and designed PGA approved golf club for golf course play and/or tournament competition. 
     Another objective is to provide golf club self contained impact sensory means of miniature size that are able to withstand repeated golf ball impact vibrations and jarring. 
     A further objective of the invention is to furnish a teaching golf club with instant feedback so that the user can make immediate adjustments and develop a correct golf swing that becomes part of the user&#39;s muscle memory. 
     In addition, a further objective of the invention is to provide a simple golf stroke teaching club to be used for a quick, self taught lesson before golf course play. 
     There is a need for putter, iron and “wood” teaching golf clubs that can be used for practice and matching golf clubs that can be used for golf course play. A player who practices with teaching golf clubs and then plays on a golf course with substantially identically shaped, weighted and balanced PGA approved golf clubs can repeat successful practice golf swings in actual play thereby gaining confidence with each swing. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a thin hard material or an elastomer cover at least one sensor element embedded on a front surface of a putter face so that a golf ball impact on the elastomer or on the thin hard material covering the putter face distorts the sensor element initiating an electrical signal received by an electrical processing circuit imprinted on a circuit board having at least one LEDs available to signal golf ball impact location. The sensor elements are affixed to an elastomer having a grid patterned surface and the sensor grid assembly can be backed by a resilient, foam like material which minimizes vibrations and intensifies the electrical signal. The electrical processing circuit detects the ball impact location using a colored LED display to inform the user of the location, the LEDs emitting one color for “sweet spot” impacts and other colors for off center impacts. The LED display output is observed by the user through apertures located on the putter top surface. Each sensor zone stimulates its own associated circuit and LED output. A golf ball simultaneously striking more than one sensor element results in the simultaneous light up of more than one LED signal showing more than one zone of impact. Switch means are provided within a club grip cap so a user can depress a reset switch to turn off an LED output signal that resulted when the putter impacted a golf ball. Then the teaching putter is ready to register another ball impact. An on/off switch in the club grip cap controls a power supply comprising a plurality of batteries in a putter shaft distal end interior. The batteries rest on a spring provided to absorb vibrations and jarring from a club head/golf ball impact. 
     For irons and “woods”, where a force generated by a golf ball impact on a club face far exceeds a force of impact on a putter, the club faces have a durable, vibration resistant golf ball impact detection system comprising at least one elastomer or thin hard material covered plate, the plate disposed to cover impact detecting sensors embedded into the club faces. For the irons and “woods”, at least one elastomer pad or the thin hard material adheres to a front surface of at least one plate and a centrally located U-shaped flexible projection extends perpendicular to the plate back surface. At least one sensor element embedded on the iron and “wood” club head faces defines a centrally located stepped down aperture that receives the U-shaped flexible projection so that the plate is snapped against an opposing sensor and more than one plate abuts an adjacent plate. As a result, elastomer pads or thin hard material on the plates&#39; front surfaces form a smooth, planar club face exterior. The impact detecting sensor elements respond to a golf ball/golf club impact force on the elastomer or thin hard material surface of a plate by sending electrical signals through a printed circuit that results in LED output that shows a golf ball point of impact on the club face. A reset switch in an iron or “wood” grip cap provides means for LED on off switching. A power supply inserted in an iron and “wood” shaft distal end interior is made available to the user through a grip cap inserted on off switch. 
     In a preferred embodiment, the putter, iron and “wood” club face sensor elements are composed of piezoelectric film with an electrode pattern having a plurality of electrodes printed with silver conductive ink on a front side of the film and a common electrode printed with silver conductive ink on a back side, the back side conductor connected to the front side via a silver plated aperture in the film. To protect the sensor elements, the piezoelectric film retains an outer coat of a plastic material such as mylar. Between the layers of silver conductive ink comprising front and back electrodes, a uniform layer of polyvinylidene fluoride (PVDF) provides voltage output upon distortion from a golf ball impact. 
     For putter, iron and “wood” clubs, the thickness of the elastomer or thin hard material is used to help control the activation of the sensor elements when a golf ball impact occurs. A putter head face has a thin elastomer or hard material cover compared to the elastomer pads or hard material faced on iron and “wood” club head faces. In addition, a light weight putter will have a thicker face cover compared to a heavier putter since the light weight putter requires more striking force to move a golf ball the same distance as with the heavier putter. Along with elastomer thickness, electrical circuitry adjusts a signal generated by the golf ball impact force to achieve a proper LED output message. 
     In another embodiment, an elastomer or thin hard materials cover for the putter and elastomer pads or thin hard cover on the plates for the irons and “woods” are coated on to piezoelectric film sensor elements which are affixed to a metal alloy backing and metal alloy plates, respectively, the metal alloy backing and plates having microscopic holes filled with a plastic type material such as silicone to ease sensor element distortion and enhance a ball impact force and corresponding electric signal. 
     The LED output display can be arranged in a plurality of numbers, patterns and light colors. In preferred embodiments, putter and “wood” club head top surfaces can display LEDs in a single horizontal row of six LEDs, the middle two being green, the end two being red and the remaining two being yellow when a single horizontal row of six corresponding sensor elements are activated by a club/ball impact. Putters and “woods” can also have LED indicators in two horizontal rows of three each where middle front and back LEDs emit green light when corresponding middle top and bottom sensor elements are stimulated, end front and back LEDs emit red light when corresponding end top and bottom end sensor elements are impacted while remaining front and back LEDs emit yellow light when remaining sensor elements are impacted. 
     A preferred embodiment for irons consists of four LEDs in a single horizontal row, the middle two LEDs emitting green lights and the end two LEDs emitting red lights responding to electrical signals generated by golf ball impacts on four iron club face sensor elements aligned in a signal horizontal row to correspond to electrically related LEDs. 
     In a preferred embodiment, putter, iron and “wood” sensor elements are arranged to be a distance apart no greater than the diameter of a professionally approved golf ball dimple diameter so that a golf ball impacting exactly between two adjacent sensors can send electronic signals simultaneously to two corresponding LEDs, both exhibiting lights giving a user accurate ball impact location information. 
     Each teaching golf club can have a matching PGA approved professional golf club for recreational and tournament golf course play. When a user makes successful, repetitive golf swings with the teaching clubs, the user develops muscle memory where successful swings are automatic. These swings developed through teaching club use can carry over to golf course play when the user employees PGA approved matching clubs having substantially the same weight, balance, size, shape and overall appearance and constructed of the same materials as the teaching clubs. 
     In accordance with another aspect of the invention, a paired set of golf clubs includes a teaching golf club having predertermined mechanical properties including weight distribution, flexibility and club face resilience, and a PGA-approved matching golf club having substantially the same predetermined properties, wherein said teaching golf club includes at least one sensor on the face of the teaching club for energization when the club impacts a golf ball, and a corresponding two-dimensional display visible on said teaching club displaying the location of the impact of the club on the golf ball, so that a golfer&#39;s swing may be improved by improving the impact location of the ball and club face through the use of the teaching club, and the golfer may subsequently carry over this teaching to the use of the correspondingly paired PGA approved golf club. It is further noted that at least one sensor may include at least two parallel horizontally spaced rows of sensors, with at least three sensors in each row. 
     Additional features as well as other advantages and a fuller understanding of the nature and objectives of the present invention will become apparent from the following detailed description of the preferred embodiment along with the accompanying drawings and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a front plan view of a teaching putter face partially broken to show sensor elements. 
     FIG. 1B is a top surface plan view of a teaching putter head showing apertures for LED light emission. 
     FIG. 1C is a front plan view of a teaching putter face showing an alternative embodiment for sensor element placement. 
     FIG. 2 is a perspective diagram of a sensor element grid assembly electrically connected to a circuit board having a printed circuit with LED output capacity. 
     FIG. 3 is a schematic diagram of a single module of an electronic circuit for a teaching putter. 
     FIG. 4 is a sectional expanded view of a teaching putter club head taken along line  4 — 4  of FIG.  1 A. 
     FIG. 5A is a top view of a teaching putter, iron or “wood” golf club shaft distal end showing switching means. 
     FIG. 5B is a sectional view of a teaching putter, iron or “wood” golf club shaft distal end taken along line  5 B— 5 B of FIG.  5 A. 
     FIG. 6A is a front plan view of a teaching iron and teaching “wood” club head showing uncovered sensor elements and elastomer or hard material coated plates covering sensor elements. 
     FIG. 6B is a top plan view of a teaching iron and “wood” club head. 
     FIG. 7 is a sectional view of the teaching iron and wood club head taken along line  7 — 7  of FIG. 6A showing one elastomer coated plate adjacent to and touching a sensor element and another elastomer coated plate with U-shaped projections not yet inserted into a sensor element aperture. 
     FIG. 8 is a schematic diagram of an electrical circuit for a teaching iron or teaching “wood”. 
     FIG. 9A is a front plan view of another embodiment of a teaching iron. 
     FIG. 9B is a top plan view of another embodiment of a teaching iron. 
     FIG. 10 is a front plan view of a PGA approved putter matching the teaching putter of the present invention. 
     FIG. 11 is a front plan view of a PGA approved iron and “wood” matching the teaching iron and “wood” of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings, and particularly FIGS. 1A,  1 B and  1 C, preferred embodiments of the present invention teaching putter  10  are illustrated comprising a putter club head  11  having at least one sensor element  12  such as a piezoelectric film sensor, embedded in the teaching putter&#39;s face  13  that generates an electrical visual signal when distorted by a golf ball impact, an elastomer cover or thin hard material  14 , having a smooth outer surface and a grooved inner surface, affixed to the club face  13  by screw means or by adhesive to protect the sensor elements  12  from golf ball impact damage and having a club head  11  top surface  15  defining at least one of aperture  16  through which output information indicating golf ball impact locations is visible. The elastomer cover or thin hard material cover  14  can be made of a rubber like material, polyvinylchloride plastic, an aluminum titanium alloy or any other resilient or metallic material. The elastomer or thin hard material cover  14  has inner surface grooves that are a minimum of 0.01 inch in width and a minimum of 0.02 inch in depth. The elastomer cover or thin hard material  14  is a minimum of 0.03 inch thick. The grooves define square or rectangular pads large enough to cover an underlying sensor element  12 . In addition to piezoelectric film, several types of impact sensitive materials including piezoresistive films and capacitive materials can be used as sensor elements  12 . The piezoelectric film can be laminated in the following order: 0.0005 inch mylar, a front silver ink electrode  17 , 28 μM PVDF film, a back silver ink electrode  18  and a clear-cut layer, the mylar layer facing to the front of the putter  10  face  13 . FIG. 2 illustrates electrodes  17 ,  18 . 
     Also, the teaching putter  10  is comprised of a shaft  19  having a distal grip portion  20  as illustrated in FIG.  5 . In addition, a foam layer  21 , as seen in FIG. 4, backing sensor elements  12  allows a golf ball impact to slightly deflect a sensor element  12  thereby maximizing an electrical signal generated from the impact. 
     In a preferred embodiment, as seen in FIG. 1A, sensor elements  12  are arranged in two parallel horizontally spaced rows of three with top and bottom central sensors  22  directly over the club face  13  sweet spot. Adjacent sensor elements  12  are separated from each other by a distance no greater than 0.05 inch so that a golf ball having a dimple diameter of 0.05 inch can impact two sensor elements  12  simultaneously with resulting simultaneous visual output signals. In one embodiment, central sensors  22  have a 0.40 inch width and end sensors  23  have a 0.50 inch width. Top row sensor elements  12  have a 0.30 inch length and bottom row sensor elements  12  have a 0.35 inch length. 
     In another embodiment, in FIG. 1C, a teaching putter  24  having sensor elements  25  in a single horizontal row array of six sensor elements  25 , each sensor element  25  separated from the other by a distance no greater than 0.05 inch. The six sensor element  25  array can be embedded in the teaching putter  24  face  26 . All other aspects of teaching putter  24  are the same as in teaching putter  10  as described above. In FIGS. 1A and 1B, the sensor elements  12  and  25 , respectively, are equal in thickness to indentations on putter faces  13  and  26 , respectively, so flat, planar club faces result. 
     Turning now to FIG. 2, an array of sensor elements  12  are shown electrically connected to a printed circuit board  27  having a printed circuit  28  as illustrated in FIG. 3 with light emitting diode (LED)  29  visual output means. The LEDs  29  are positioned in order to be received by apertures  16 , the LEDs  29  projecting upward within apertures  16  to a distance below club head  11  top surface  15 . Printed circuit board  27  slips into a teaching putter  10  club head  11  cavity and is secured within the cavity walls by friction force or, if necessary, by screw means. In another embodiment, printed circuit board  27  is embedded in a molded plastic matrix forming part of a putter club head  11 . 
     FIG. 3 shows a schematic diagram of a single module of printed circuit  28  illustrating a means for transmitting an electric signal generated from a golf ball impact on a sensor element  12  or a sensor element  25  to a visual LED  29  output indicating an impact location. Simultaneous golf ball impacts on more than one sensor element  12 ,  25  results in simultaneous visual LED outputs. The number of modules needed depends on the number of sensor elements  12  or sensor elements  25  in a teaching club. When more than one LED  29  output is desired, a plurality of modules are connected to the same power supply  30 , having a common reset button  31 , both seen in FIG.  5 . Every module with LED output is the same regarding sensitivity adjustments. 
     Now turning to printed circuit  28 , when on off switch  32  is turned on, power supply  30  comprising two 3 volt batteries supply power to voltage regulator U 7  that, in turn, supplies circuit  28  with a transistor to transistor voltage of 4.5 to 5.0 volts. A signal from piezoelectric film sensor element  1 , PFS 1 , representing one sensor element  12 , is initially amplified through operational amplifier U 1  which is connected in a differential mode open loop for high sensitivity. R 1  and R 2  limit two inputs of current, from PFS 1  and from power supply  30 , to U 1 . When PFS 1  is undisturbed, the voltage on non inverting input is maintained at 2.5 volts. This is achieved with a voltage divider made of resistors R 36  and R 37  having a resistance of 2.2 Mohm each. Inverting input is also adjusted to a potential of about 2.5 volts. A small difference from the 2.5 voltage is adjusted in order to give the output of the operating amplifier U 1  voltage high enough for chips U 4  logical HI. This adjustment of inverting input potential is achieved through resistor  20 T. Since the output of operating amplifier U 1  is HI, pin No.  1  of a first NAND gate contained in chip U 4  is HI as well. With a second NAND gate of U 4 , pin No.  1  forms a set/reset latch. A reset pin, pin No.  6  of the set/reset latch is HI. Therefore, the output of the latch is LOW. This condition keeps an LED  29  turned off since a driving transistor Q 1  has no electrical potential on its base. When an impulse from PFS 1  occurs, the operating amplifier U 1  provides an output in a range of logical LOW that results in the output of the set/reset latch to turn HI. This HI output, limited by resister R 3 , turns on transistor Q 1  and the LED  29  turns on as well. The circuit  28  stays latched in this HI position even though the PFS 1  signal is no longer present. Finally when pin No.  6  is brought to a LOW position by a putter  10  user who presses the reset button  31 , the latch is reset and the circuit  26  is ready to register another impulse from the PFS 1 . When the circuit  28 , as shown in FIG. 3 is in a highly sensitive mode, the club face  13  elastomer or thin hard cover  14  can be thick and the club head  11  weight can be low. Circuit  28  sensitivity can be lower when the elastomer or thin hard cover  14  is thin and the club head  11  is heavy. Ideally, the elastomer or thin hard cover  14  ranges in thickness from 0.375 inch to 0.03125 inch. 
     Returning to FIG. 1A, electrical impulses from central sensor elements  22  can turn on middle LEDs  29  that can be green in color, a lower sensor  22  corresponding to a middle front LED  29  and an upper sensor  22  corresponding to a middle back LED  29 . When end sensors  23  impact a golf ball, end LEDs  29  and lower sensor  23  can correspond to end back LED  29 . Other LED  29  color combinations can be substituted to provide an immediate and easily understood signal indicating golf ball/golf club point of impact. The ability to increase or decrease the number and arrangement of sensor elements  12  and corresponding LEDs  29  is only limited by a club head size. A teaching putter  10  club head  11  face  13  can have one sensor element  12  placed on a sweet spot and one corresponding LED  29 . 
     In FIG. 4, a section taken along line  4 — 4  of FIG. 1A of the teaching putter  10  shows the elastomer or thin hard material cover  14  with back surface grooves  33  the sensor elements  12  affixed to a resilient elastomer padding  34 , a foam backing  21 , electrical connections  35 , between sensors  12  and circuit board  27 , LEDs  29  and apertures  16 . 
     Referring again to FIG. 1C, the single row of sensor elements  25 , upon golf ball/golf club impact, can send impulses through circuit  28  to activate LED  29  point of impact information. Center sensor elements, numbered one for identity, can activate green LEDs  29 , sensor elements numbered two for identify can activate yellow LEDs  29  and sensor elements numbered three for identity can activate red LEDs  29  using FIG. 3 circuitry. LEDs  29  are observed through the putter  10  top surface  15  apertures  16 , the apertures  16  arranged in a single horizontal row. 
     FIG. 5A is a top view of a teaching putter, iron or “wood” golf club shaft distal end showing switching means including on off switch  32  and reset button  31 . FIG. 5B is a sectional view of a teaching putter, iron or “wood” golf club shaft distal end taken along line  5 B— 5 B of FIG. 5A showing power supply  30 . On off switch  32  makes available the power supply  30  for the printed circuit  28  as illustrated in FIG.  3 . With the on off switch  32  on, an electrical impulse from a sensor elements  12  or  25  results in an LED  29  emitting light which remains on until a user presses the reset button  31 . Then the LED  29  is ready to again emit light when a golf ball deflects sensor elements  12  or  25 . 
     Referring to FIG. 6A, at least one sensor element  36  inserted on teaching irons and “woods”  37  club faces  38  and at least one plate  39  disposed to cover the sensor element  36  are illustrated. The sensor element  36  is preferably a piezoelectric film sensor. Each sensor element  36  defines a centrally located preferably square shaped, stepped down aperture  40 . In FIG. 7, a sectional view taken through line  7 — 7  of FIG. 6A, plate  39  has a front elastomer or thin hard material covered front surface  41  and centrally located flexible U-shaped projections  42  perpendicularly affixed to a back surface  43 . The U-shaped projections  42  have leg portions  44  with outwardly bend distal ends to provide securing means for plate  39  to iron and “wood” club face  38  so that insertion of plate  39  projections  42  into stepped down aperture  40  results in the plate  39  back surface  43  pressing against and covering sensor element  36  to minimized iron and “wood”  37  club head vibrations from golf ball impacts. Plate  39  can be fabricated from a metal alloy or high impact plastic material in order to withstand high impact forces but also have flexible U-shaped projections  42  leg portions  44 . Each sensor element  36  is covered by a plate  39 . In the sensor  36  array as illustrated in FIG. 6A, plates  39  are adjacent and touching. Touching plates  39  elastomer covered surfaces  41  result in a smooth, planar club face  38 . As illustrated in FIG. 2, sensor elements  36  in the same manner as sensor elements  12  are electrically connected to a circuit board having LED  45  output signal means. LEDs  45  are observed through iron and “wood”  37  top surface  46  apertures  47  as illustrated in FIG.  6 B. 
     FIG. 8 is a schematic representation of LED  45  output circuitry  48  for iron and “woods”  37  having sensor element  36  arrays as shown in FIGS. 6A and 9A. Represented is one segment of a plurality of electrically connected identical circuits  48  having a common power supply  30 , on off switch  32  and reset button  31 . The on off switch  32  can be flush with or set into a club grip cap and the reset button  31  can be set into or flush with a club grip. See FIG.  5 . Each segment as illustrated in FIG. 8 has one sensor element  36  corresponding to one LED  45  output signal. The number of sensor elements  36  and corresponding LEDs  45  are limited only by an iron or “wood” club head size. 
     In circuit  48  as diagramed in FIG. 8, a piezoelectric sensor element  36  labeled S 1  has a 450 pF capacitance when it is not disturbed. At the time of impact, this capacitance momentarily changes to up to 40% of its nominal value. At that time, positive voltage passes through a plate of S 1 . Additionally, due to piezo effect, a small amount of voltage is generated and added to voltage from power supply  30 . This supplies enough power to turn on transistor Q 1  and, therefore to make pin No.  2  of chip U 1  HI and turn on LED  45 . Once an initial signal from a golf ball impact distortion of S 1  disappears, the HI state is maintained through pin No.  2  feedback. Therefore, LED  45  remains on as long as reset button  31  is not pressed. 
     In FIG. 9A, an array of four sensor elements  36  in a single horizontal row showing two sensor elements  36  covered by two plates  39  illustrate another arrangement for iron and “wood” ball impact information. Apertures  47 , as shown in FIG. 9B, provide means for observing LEDs  45 . Plates  39  have elastomer or thin hard material front surface covers  41  and back surface  43  projections  42  which are received by sensor elements  36  centrally placed apertures  40 . The plates  39  are illustrated in FIG.  7 . As in FIG. 7, plates  39  back surfaces  43  are pressing against and covering sensor elements  36 . Plates  39  are adjacent and touching to form a smooth, planar iron and “wood”  37  club face  38 . All other aspects of the iron and “wood”  37  as illustrated in FIGS. 9A and 9B are the same as those described above for the FIGS. 6A and 6B iron and “wood”  37  teaching clubs. 
     Returning to FIG. 2, teaching putters printed circuit  26  as illustrated in FIG.  3  and irons and “woods” printed circuit  48  are each separately embedded on circuit boards  27  and inserted into respective club head cavities, the circuit boards  27  secured tightly by friction force, screw means or in any manner that will firmly hold the circuit boards  27  in place. In another embodiment, iron and “wood” printed circuit  48  separately embedded on circuit boards  27  can be inserted in a molded plastic matrix forming part of a iron and “wood” club head. 
     Referring to FIG. 10, a PGA approved putter  49  is illustrated having an elastomer or thin hard material face cover  50  affixed to a solid, flat, planar face plate and having a presently known conventional top wall  51 , side wall and club head construction. Putter  49  can be substantially identical to the putter  10  as illustrated in FIG.  1 A and the club shaft as illustrated in FIG. 5 in weight, balance, size, shape, construction materials and general appearance. 
     FIG. 11 illustrates a PGA approved iron and “wood”  52  having a solid, flat, planar face  53 , a spheroidal top wall  54 , spheroidal side walls  55  and a sole plate of conventional iron and “wood” club head construction. The iron and “wood”  52  can be substantially identical to the teaching irons as illustrated in FIGS. 6A,  6 B,  9 A and  9 B, and the club shaft as illustrated in FIG. 5 in weight, balance, size, shape, construction materials and general appearance. 
     Even though the present invention has been described with respect to preferred embodiments, one of ordinary skill in the art can make many changes and modifications in form and detail in the golf clubs of the present invention to adapt them to certain conditions and usages without departing from the scope and spirit of the invention. In this regard, by way of example, sensors other than piezoelectric sensors may be used, for example, variable capacitor and variable resistance sensor as shown in U.S. Pat. Nos. 4,388,668 and 5,349,867. In addition, instead of being in a “separate” cavity, the electronics may be encapsulated and embedded in a high strength plastic matrix forming a part of the club head. Accordingly, the present invention is not limited to the embodiments more specifically described herein; and all such changes and modifications are properly intended to be within the full range of equivalents of the following claims.