Patent Publication Number: US-6213917-B1

Title: Swimmer&#39;s training method

Description:
FIELD OF THE INVENTION 
     This invention relates to training methods and more particularly to a method for improving a swimmer&#39;s performance. 
     BACKGROUND OF THE INVENTION 
     Small changes in form or movement, such as changes in the angle of a hand or the movement of a head can significantly reduce the swimmer&#39;s speed and increase fatigue. Heretofore, only lap counters and timing devices such as stop watches have been used for evaluating a swimmer&#39;s performance. The effects of small changes in form and movement have either been overlooked or not been readily detectable by either the swimmer or an observer such as a coach. Consequently, there was no way for the swimmer to know, while swimming, whether a specific change in his swimming technique increased or decreased his speed. 
     Linden, U.S. Pat. No. 4,796,987; Kreutzfeld, U.S. Pat. No. 4,823,367; and Malone, U.S. Pat. No. 4,780,085 are exemplary of the prior art. Linden merely discloses a stop watch mounted in a transparent lens of a goggle, mask, or shield worn by a swimmer. The stop watch reset button is manually activated by the swimmer before the swimmer starts swimming and after the swimmer stops swimming. 
     Kreutzfeld discloses an apparatus for counting the number of laps of a swimmer comprised of a portable unit worn by the swimmer and a stationary unit which establishes a zone of detection. Each time the portable unit passes the stationary unit a signal is conveyed to register a completion of a lap. 
     Malone discloses a lap timing device consisting of a clock/timer, a switch for starting the clock/timer and a proximity sensor for detecting a completion of a lap. 
     SUMMARY OF THE INVENTION 
     A principal object of the present invention is to enable a swimmer to immediately determine, while swimming, whether small changes in form and/or movement have improved or deteriorated his swimming performance. Another object is to provide a portable training apparatus which can be attached to a swimmer. 
     These objects are accomplished by attaching a compact module to a mid portion of a swimmer which transmits a train of audio signals to the swimmer that vary directly in frequency with the swimmer&#39;s speed. The invention resides in novel steps which individually and collectively contribute to its ability to immediately inform a swimmer of the effects of changes in his form and/or movements and thus enable him to optimize his technique. 
     One characteristic feature of the invention is that an audio signal is used to inform a swimmer of whether his speed has increased or decreased. Another characteristic feature is that a compact module is attached to the swimmer for monitoring the swimmer&#39;s performance. 
     Another feature of the invention is that the module is automatically activated when it is immersed in water and deactivated when it is taken out of the water. Another feature of the invention is that the module can be re-positioned on a swimmer to accommodate different swimming strokes. 
     In a first form of the module, a propeller rotates about an axis which is aligned with the path of the swimmer. A permanent magnet driven by the propeller produces rotating magnetic field which acts on a magnetic field transducer, such as a Hall effect or magneto-resistive transducer to produce a pulsating signal whose frequency varies directly with the swimmer&#39;s speed. The sensor&#39;s output is multiplied, amplified and fed to an earphone worn by the swimmer. Changes in frequency immediately inform the swimmer of whether his performance has improved or deteriorated. 
     In a second form of the module, permanent magnets are driven by an impeller which rotates about a horizontal axis which is at right angles to the path of the swimmer. Rotating magnetic fields of the magnet act on a magnetic field sensor. 
     Further objects, benefits and features of the invention will become apparent from the ensuing detailed description and drawings which disclose the invention. The property in which exclusive rights are claimed is set forth in each of the numbered claims at the conclusion of the detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be better understood and further objects, characterizing features, details and advantages thereof will appear more clearly with reference to the diagrammatic drawings illustrating a presently preferred specific embodiment of the invention by way of non-limiting example only. 
     FIG. 1 is a right side view of a swimmer with a training apparatus according to my invention. 
     FIG. 2 is a plan view of a module of the training apparatus which is mounted on the underside of the swimmer in FIG.  1 . 
     FIG. 3 is a front view of the module. 
     FIG. 4 is a right side view of the module. 
     FIG. 5 is a rear view of the module. 
     FIG. 6 is an enlarged bottom view of the module. 
     FIG. 7 is an enlarged cross-sectional view taken on the line  7 — 7  in FIG.  2 . 
     FIG. 8 is an enlarged cross-sectional view taken on the line  8 — 8  in FIG.  7 . 
     FIG. 9 is an enlarged cross-sectional view of an alternate embodiment taken in a similar manner as FIG. 8 wherein a ring magnet is mounted on a propeller. 
     FIG. 10 is an enlarged cross-sectional view of an alternate embodiment taken in a similar manner as FIG. 8 wherein a bar magnet is mounted in spaced relationship on a common shaft with a propeller. 
     FIG. 11 is a cross-sectional view taken on the line  11 — 11  in FIG.  10 . 
     FIG. 12 is a plan view of an alternate embodiment of a swimmer&#39;s training apparatus wherein a pair of magnets are mounted on an impeller. 
     FIG. 13 is a right side view of the alternate embodiment shown in FIG.  12 . 
     FIG. 14 is a bottom view of the alternate embodiment. 
     FIG. 15 is a front view of the alternate embodiment. 
     FIG. 16 is an enlarged cross-sectional view taken on the line  16 — 16  in FIG.  12 . 
     FIG. 17 is a block diagram of the swimmer&#39;s training apparatus shown in FIGS. 1-8. 
     FIG. 18 is block diagram of an alternate embodiment of FIG.  17 . 
     FIG. 19 is a comparison graph of an ear&#39;s response at 20 Hz compared to that at 1,000 Hz. 
     FIG. 20 is a block diagram of a water activated switch. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings wherein like numerals designate like and corresponding parts throughout the several views, a training apparatus for improving a swimmer&#39;s performance is shown in FIGS. 1 through 8 inclusive. Actual tests of the invention have shown the apparatus to be very effective for improving a swimmer&#39;s performance. 
     The basic concept of the invention is to apply the remarkable power of the human ear to analyze sounds to improve a swimmer&#39;s performance. As shown in FIG. 19, the sensitivity of the human ear to sound is greatest around 3 Khz and decreases with lower 
     Everest, in the  Master Handbook of Accoustics,  discloses “there are about 280 discernible steps in intensity and some 1,400 discernible steps in pitch that can be detected by the human ear.” (Everest, page 849). 
     The power of the ear to analyze sounds is used by transmitting to a swimmer an audio signal whose frequency varies in accordance with the swimmer&#39;s speed. Changes in properties of the audio signal, such as pitch and frequency, immediately inform the swimmer of whether his performance has improved or deteriorated. 
     In FIG. 1, a compact module  22  is mounted on an unobstructed mid-portion of a swimmer  23  and is connected to an earphone  24  worn by the swimmer  23 . The module  22  transmits a pulsating audio signal to the swimmer  23  whose frequency varies directly with the swimmer&#39;s speed. By way of example, if the swimmer&#39;s speed increases, the frequency of the audio signal linearly increases. Changes in audio frequency immediately inform the swimmer  23  of whether he is speeding up or slowing down. 
     The preferred embodiment can be broadly understood by the following description with reference to the block diagram in FIG. 17. A propeller  25  in suspended relationship with the module  22  is driven by the forward motion of a swimmer  23 . The propeller  25  has a pair of permanent magnets  28  and  29  mounted at the ends of a pair of opposing blades  27 . One of the permanent magnets  28  has an outward facing north pole and the other  29  has an outward facing south pole. A forward motion of the swimmer  23  causes the propeller  25  to rotate and produces pairs of rotating magnetic fields. A magnetic field sensor  30 , such as a Hall or a magneto-resistive magnetic field sensor within the rotating magnetic fields produces a pulsating output signal which varies directly in frequency with the speed of the swimmer  23 . 
     The frequency of the sensor&#39;s output signal is multiplied by a frequency multiplier  31 , amplifier  32  and fed to the earphone  24  worn by the swimmer  23 . Changes in signal frequency immediately inform the swimmer  23  of whether his speed is increasing or decreasing. A volume control  33  is provided to compensate for changes in battery voltage, background noise and the hearing capability of the swimmer  23 . 
     Referring now to FIG. 7, the magnetic field sensor  30  is a conventional type digital output transducer, such as a digital output Hall sensor or magneto-resistive sensor. The sensor  30  has two output states, namely, an “ON” and an “OFF” state. Each time a north facing pole passes the sensor  30 , the sensor&#39;s output goes low and remains low until a south facing pole passes the sensor  30 , causing the sensor&#39;s output to go high. During each rotation of the propeller  25 , the sensor  30  produces one pulse. At a given propeller speed, the number of pulses per revolution can be increased by increasing the number of pairs of poles on the propeller and/or multiple sensors. Since the speed of the propeller  25  varies directly with the speed of the swimmer, the sensor  30  in the rotating magnetic field provides a convenient means for evaluating changes in a swimmer&#39;s performance. 
     A pulsed sensor signal can also be obtained with a single permanent magnet. In FIG. 9, an embodiment is shown wherein a single ring magnet  34  with sequential pairs of north and south poles is driven by a propeller  35 . The ring magnet may be mounted on the propeller  35  or a shaft which supports the propeller  35 . During each revolution of the propeller  35 , the sensor  30  produces a pair of pulses. 
     In FIGS. 10 and 11, a further example is shown wherein a single bar magnet  36  is mounted for rotation on a common shaft  37  in spaced relationship with a propeller  38 . The magnetic field of the bar magnet  36  acts on the magnetic field sensor  30  and produces a single sensor pulse during each revolution of the propeller  38 . 
     Frequency multiplication provides two important benefits. First, the effects of changes in a swimmer&#39;s form and movement on the swimmer&#39;s speed are magnified. For example, with a frequency multiplication of 100, a change of 2 revolutions per second of propeller speed produces a frequency change of 200 cycles per second in the audio signal which is transmitted to the swimmer  23 . Second, higher audio frequency signals are more discernible over background noise. 
     Suitable frequency multiplier circuits are well known in the art and include such circuits as frequency multipliers, digital up-counters, etc. Suitable audio amplifiers are also well known in the art. A frequency multiplier  31  may multiply the frequency by a fixed amount or be selectively adjustable by the swimmer  23 . In FIG. 18, an embodiment is shown wherein a pair of optional frequency multipliers  39  arranged in parallel are selected by a switch  40 . 
     With reference to FIGS. 7 and 8, electronic components including, an “On/Off” switch  54 , a pair of batteries  42 , a volume control  33 , the magnetic field sensor  30 , the frequency multiplier  31 , and the audio amplifier  32  are mounted in a sealed housing  44 . The housing  44  has a lower half  45 , an upper half  46  and a seal  47  between the upper  46  and lower  45  halves. Inside of the housing  44  is a circuit board  48  which carries the frequency multiplier  31 , the audio amplifier  32 , and usual supporting components. The “On-Off” switch  54  and a volume control  33  extends through the lower half  45  of the housing  44 . Attached to the volume control  33  is a knob  50  for adjusting the volume of the audio signal. 
     Mounted on the top of the housing upper half  46  is a bracket  51  which receives a belt  52  for attaching the module  22  to the swimmer  23 . The position of the module  22 , i.e., at a mid-point of the swimmer  23  is a feature of the invention. It provides an unobstructed water path in the direction of arrow “A” to the propeller  25  which is mounted for rotation in a shroud  53  which is attached to the underside of the housing  44 . While performing a backstroke, the module  22  is preferably repositioned to the swimmer&#39;s back. The propeller  25  rotates about an axis which is aligned with the path of the swimmer  23 . 
     The “ON/OFF” switch  54  which is believed to be novel is a normally open water activated switch circuit which closes when the module  22  is immersed in water and opens when it is removed from water. The switch  54  provides the benefit of automatic operation and simplifies the requirement for a waterproof switch. When the module  22  is immersed in water, contact of the water with two exposed contacts  55  of switch  54  activates an “On-Off” circuit. With reference to FIG. 20, the switch  54  is connected to the batteries  42  and a circuit which remains active when power is interrupted from the other circuits. When the training apparatus is not in use, the active circuit which the switch  54  is connected to draws a negligible current, commonly referred to as “quiescent current” in the microamp range. When the module  22  is immersed in water, contacts  55  are shorted and a transistor  56  is turned on thereby energizing a relay coil  57 . The relay&#39;s contacts  58  close, supplying power to the other circuits. 
     Referring now to FIGS. 12 through 16, inclusive, an alternate embodiment is illustrated having an impeller  59  mounted for rotation in a housing  60  which is suspended from a module  61 . On the sides of the module  61  are a pair of integral brackets  62  which receive a belt  52  for attaching the module  61  to the swimmer  23 . 
     A forward portion of the impeller housing  60 , as shown in FIG. 13, is open to allow water to enter the housing  60 . The impeller  59  is suspended inside the housing  60  on a slender shaft  64 . A lower portion of the module  61  has a recess  65  to position the impeller  59  close to a magnetic field sensor  30  inside the module  61 . 
     The slender shaft  64  is oriented at right angles to the path of the swimmer  23  whereby when the swimmer  23  moves through water as shown in FIG. 1, water enters the housing  60 , causing the impeller  59  to rotate about an axis which is at right angles to the swimmer&#39;s motion. In a forward portion of the housing  60  are vanes  43  to reduce turbulence and improve the flow of water through the housing  60 . 
     Referring now to FIG. 16, a pair of bar magnets  66 ,  67  are attached to two opposite vanes  43  of the impeller  59 . One of the bar magnets  66  has an outward facing north pole and the other of the magnets  67  has an outward facing south pole. A rotation of the impeller  59  produces rotating magnetic fields which act on the sensor  30  to produce a pulsed output. 
     From the foregoing, it will be appreciated that my invention provides a compact training apparatus which is adapted to be worn on a swimmer. Moreover, the training apparatus instantly informs a swimmer whether changes in form and movement improve or deteriorate his swimming performance. 
     Although only two embodiments have been illustrated and described, it is not my intention to limit my invention to these embodiments, since changes in material, shape, arrangement of components and substitution of components can be made without departing from the spirit thereof. By way of example, linear output magnetic field sensors with amplitude to digital (A to D) converters can be used in lieu of digital output magnetic field sensors.