Abstract:
The present invention relates to a safety off switch for a treadmill exercise device. If the treadmill exercise device running belt is still rotating even after user has left the treadmill exercise device, then, after a programmed time duration, the treadmill exercise device automatically turns off the running belt and/or completely powers itself down.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. patent application No. 10/420,990, which was filed on Apr. 22, 2003, pending, which is a division of U.S. patent application Ser. No. 09/444,276, which was filed on Nov. 19, 1999, now U.S. Pat. No. 6,575,878, and which claimed the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/109,083, which was filed on Nov. 19, 1998. Each of these prior applications is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to the field of exercise equipment, specifically a motorized treadmill exercise device with an automatic safety shut-off feature.  
       BACKGROUND OF THE INVENTION  
       [0003]     Treadmill exercise devices are an integral part of the habitual, aerobic workouts of a culture focused on health and fitness. In the wake of the popularity of treadmill exercise devices, however, certain concerns arise as to the safe and proper use of treadmill exercise devices. In this regard, it is particularly desirable to prevent a treadmill exercise device from being inadvertently left operating after a user has left the device. This is desirable to conserve energy and also to prevent possible risk of someone getting injured by the moving parts of a treadmill exercise device left running.  
         [0004]     A treadmill exercise device that has been left running by a user wastes energy. Especially in a home setting if the user is called away from the treadmill exercise device and forgets that the treadmill exercise device is running, the treadmill exercise device can consume energy for extended durations. In a gymnasium or fitness center, a plurality of treadmill exercise devices if left running when not in use would consume substantial energy.  
       SUMMARY OF THE INVENTION  
       [0005]     What is needed is a system and method for automatically powering down the treadmill exercise device when the user has left the treadmill. Accordingly, safety for future users would be enhanced if the treadmill exercise device had the capability of sensing when the previous user has left the treadmill exercise device so that the treadmill exercise device can subsequently, automatically power itself down for future users.  
         [0006]     Preferred embodiments of the present invention provide a treadmill comprising a motor and a control panel including control circuitry. The control panel is adapted to monitor and control the motor. The circuitry is adapted to automatically power down the control panel and the motor when the circuitry has sensed a threshold change in an electrical perturbation from the motor during a time duration.  
         [0007]     Preferred embodiments of the present invention also provide a treadmill exercise device comprising means for determining when the treadmill exercise device is not being used and means responsive thereto for automatically powering down the treadmill exercise device.  
         [0008]     Preferred embodiments of the present invention also provide an exercise device comprising a motor and current detection circuitry coupled to the motor. The circuitry is adapted to sense when no one is using the exercise device based upon changes with respect to time in the current supplied to the motor.  
         [0009]     In one embodiment, the current detection circuitry comprises a current sensor for detecting changes in current with respect to time, an amplifier coupled to the current sensor, a filter coupled to the amplifier, and an integrator coupled to the filter.  
         [0010]     In other advantageous embodiments of the exercise device, the filter is a low pass filter or a bandpass filter. Furthermore, the filter may be digital or analog. In still other embodiments, the amplifier transforms and amplifies current signals into voltage signals.  
         [0011]     In another embodiment, the exercise device further comprises an analog-to-digital converter coupled to the integrator. In yet another embodiment, the exercise device further comprises a threshold detector coupled to the integrator and a timeout circuit coupled to the threshold detector. Optionally, the timeout circuit may comprise a resetable programmable counter.  
         [0012]     The present invention, in another embodiment, provides a method for automatically switching off a rotating running belt in a treadmill exercise device when no one is using it, comprising the steps of sensing a threshold change in electrical perturbations from a motor in the treadmill exercise device during a first time duration and automatically powering down the treadmill exercise device after a second time duration if electrical perturbations are not detected.  
         [0013]     The present invention also provides, in another embodiment, a method for automatically powering down an exercise device when no one is using the exercise device, comprising the step of detecting changes with respect to time in current supplied to a motor. In another embodiment, the step of detecting changes comprises the step of inducing a current signal in a current detection circuit. In yet another embodiment, in addition to the step of the previous embodiment, the method further comprises the steps of amplifying the current signal, transforming the current signal into a voltage signal, filtering the voltage signal, and integrating the voltage signal with respect to time.  
         [0014]     Other advantageous embodiments for automatically powering down the exercise device when no one is using the exercise device include the step of filtering by passing low frequencies. Another embodiment includes the step of filtering by filtering low frequencies and filtering high frequencies.  
         [0015]     In addition, another advantageous embodiment comprises the steps of comparing the integrated voltage signal value with a threshold value, enabling a timeout circuit, and automatically powering down the exercise device. Furthermore, in yet another embodiment, the step of enabling comprises the step of resetting the timeout circuit. Moreover, in another embodiment, the step of enabling comprises the step of enabling and resetting a resetable counter programmed for a time duration.  
         [0016]     The present invention also provides a method for automatically detecting changes in current with respect to time comprising the steps of inducing a current signal in a current sensor, amplifying the current signal, transforming the current signal into a voltage signal, filtering the voltage signal, and integrating the voltage signal. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The present invention is described in more detail below in connection with the attached drawing figures of a preferred embodiment, which is intended to illustrate, but not to limit, the present invention, in which:  
         [0018]      FIG. 1  illustrates an user using a treadmill exercise device;  
         [0019]      FIG. 2  illustrates a state diagram for the treadmill exercise device; and  
         [0020]      FIG. 3  illustrates a block diagram for a motor control system and a current detection system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     One preferred embodiment of the present invention provides circuitry for sensing when a user has left the treadmill exercise device by detecting the absence of perturbations in the current supplied to the motor. The circuitry automatically powers down the treadmill exercise device when no user motion is sensed.  
         [0022]      FIG. 1  illustrates a user  110  walking, jogging or running on a treadmill exercise device  112  in accordance with one embodiment of the present invention. The treadmill exercise device  112  comprises a control panel  114 , a support structure  116 , and a base  118  with support structure vias  126 . The support structure  116  is mounted to the top of the base  118  at the support structure vias  126 . The control panel  114  is mounted on top of the support structure  116 . The user  110  is supported on top on the base  118 . The user  110  may also grip part of the support structure  116  for added stability.  
         [0023]     The base  118  further comprises a housing  120 , a running belt  122 , a running deck (not shown), and a motor (not shown). The housing  120  houses the motor which is coupled to the running belt  122 . The running deck is positioned on top of the housing  120  and supports the user  110  and the running belt  122 . The running belt  122  is positioned on top of and below the running deck and is supported by rollers or other means (not shown).  
         [0024]     The control panel  114  preferably includes circuitry (not shown) adapted to monitor and control the motor. Of course, the exact location of the circuitry is not particularly important and all or part of the circuitry may be located elsewhere in the treadmill exercise device  112 . The circuitry is in electrical communication with the motor such as through the support structure  116 . In one embodiment, the support structure  116  comprises hollow tubing adapted to provide support to the user  110  and also to house electrical wiring. The electrical wiring provides electrical communication between the circuitry of the control panel  114  and the motor in the base  118 .  
         [0025]     In operation, the user  110  approaches the treadmill exercise device  112  and steps onto the running belt  122 , supported by the running deck, the user being at an optimal distance, as determined by the user  110 , from the control panel  114 . The user  110  then programs the control panel  114  by entering information such as the weight of the user  110  and the speed at which the user  110  wishes to walk, jog or run. The control panel  114  processes the information and uses control circuitry to start the motor. The motor causes the running belt  122  to rotate around the running deck and through the housing  120 .  
         [0026]     As the running belt  122  rotates, the user  110  takes strides at a rate commensurate with the speed of the running belt  122 . During each stride, a foot  124  of the user  110  creates an impact on the running belt  122  which is a function of the weight of the user  110 . Accordingly, the running belt  122  is forced into greater contact with the running deck resulting in an increased frictional force which appears at the motor in the form of a torque disturbance. The frictional force is a function of the weight of the user  110  and the effective coefficient of friction between the running belt  122  and the running deck. The torque disturbance impresses an electrical perturbation in the form of a back electromotive force in the motor which is sensed by the circuitry in the control panel  114  which is in electrical communication with the motor.  
         [0027]     Thus, an approximately periodic rate of foot impacts by the user  100  who may be walking, jogging or running, creates an electrical signal reflecting the approximately periodic electrical perturbations. This signal is monitored by the circuitry in the control panel  114 . If the user  110  falls or leaves the running belt  122  while the running belt  122  is still rotating, the circuitry will no longer sense the electrical perturbations caused by the user  110 .  
         [0028]     In one embodiment, if the amplitude of the signal reflecting the electrical perturbation stays below a threshold value during a first period of time, then the circuitry will, after a second period of time, automatically power down the motor and/or the control panel  114 . In such an embodiment, a threshold value must be set or determined in which the circuit distinguishes between the electrical signal reflecting the electrical perturbation caused by a user and the electrical signal reflecting electrical noise. One alternative is to set the threshold value equal to a multiple of, e.g. two, three or four times, the average electrical noise signal. Another alternative is to set the threshold value as a function of the weight of the user  110 . One such alternative might set the threshold value to, for example, fifty percent of the peak amplitude of the signal reflecting the electrical perturbation created by a user  110  of the programmed or default weight.  
         [0029]     In such an embodiment, the first period of time must be either determined or arbitrarily set. One alternative for determining the first period of time is to make the period a function of the programmed or actual speed of the running belt  122 . In such an alternative, a slower moving running belt  122  would need a longer first period of time than a faster moving running belt  122 . Likewise, the first period of time can be a multiple of the period of time required for the running belt  122  to make one full rotation. In the aforementioned embodiment, the second period of time can be set by the manufacturer.  
         [0030]     In another embodiment, the signal reflecting the electrical perturbation is processed by the circuitry to produce a value which is compared to another threshold value. If the processed signal values stay below a threshold value during a first period of time, then the circuitry will, after a second period of time, automatically power down the motor and the control panel  114 . In this embodiment, the first and second periods of time can be determined as previously discussed for other embodiments and alternatives.  
         [0031]     In one alternative, the signal reflecting the electrical perturbation is integrated over a time duration to produce the value. The time duration over which the signal is integrated can be set by the manufacturer as a default time duration or can be a function of the actual or programmed speed of the running belt  122 . Alternatively, the time duration can be a function of the average of the last, for example, three time intervals between electrical perturbations or foot impacts. The time duration can be variable or constant, but should preferably be at least long enough such that the time duration encompasses the time interval between foot impacts when the user  110  has slowed from a run down, in which short time durations are needed, to a slow walk, in which long time durations are needed.  
         [0032]      FIG. 2  is a state diagram illustrating the operation of the treadmill exercise device  112  in accordance with one embodiment of the present invention. The three states  202 - 204  illustrated by  FIG. 2  are STOP, RUN and TIMING, respectively. The STOP state  202  indicates that the running belt is not moving. As indicated by “/Start”  206 , until a start process is completed, the treadmill exercise device remains in the STOP state  202 . In one embodiment, the start process includes programming the control panel  114  through a user interface to control and manipulate the motor in the base  120  in order to get the running belt  122  moving. Once the start process is completed  208 , the treadmill exercise device  112  moves into the next state, the RUN state  203 .  
         [0033]     In the RUN state  203 , the running belt  122  is moving across the running deck. The treadmill exercise device  112  can move from a RUN state  203  back to a STOP state  202  if a stop process  210  is completed. In one embodiment, the stop process includes programming the control panel  114  by the user  110  through a user interface. The treadmill exercise device  110  moves from the RUN state  203  into the TIMING state  204  once the pulse process is in progress  212 . In one embodiment, the pulse process includes detecting a certain number of pulses representing the electrical perturbations within a first period of time. In another embodiment, the pulse process includes processing electrical signals from the motor and comparing the processed signal values to one or more threshold values over a first period of time.  
         [0034]     In the TIMING state  204 , a timer counts out a preset time interval, shown as a timeout process in  FIG. 2 . While the treadmill exercise device is in the timeout process  214 , the treadmill exercise device  112  remains in the TIMING state  204 . Should the pulse process be completed during the timeout process  216 , then the treadmill exercise device  112  would return back to the RUN state  203 . In one embodiment, the successful completion of the pulse process before the end of the timeout process  216  indicates that the user  110  is still walking, jogging or running. However, should the timeout process be completed before the completion of the pulse process  218 , then the treadmill exercise device  112  would move into the STOP state  202 . In one embodiment, the completion of the timeout process  218  before the completion of the pulse process indicates that the user  110  has left the treadmill exercise device  112 . A transition from the TIMING state  204  to the STOP state  203  may also be achieved if the stop process  218  is completed.  
         [0035]      FIG. 3  illustrates a simplified, schematic block diagram of a motor control system  310  and a current detection system  311  in accordance with one embodiment of the present invention. The current detection system  311  is coupled to the motor control system  310 .  
         [0036]     The motor control system  310  comprises a motor drive  314 , a drive level line  316 , and a plurality of connection lines  318 . The drive level line  316  is in electrical communication with an input to the motor drive  314 . In one embodiment, the drive level input line  316  is in electrical communication with circuitry located in the control panel  114 . The motor drive  314  is in electrical communication with the motor  312  through the connection lines  318 .  
         [0037]     The current detection system  311  comprises a current sensor  320 , an amplifier  322 , a filter  324  and an integrator  328 . The current sensor  320  is coupled to an input of the amplifier  322 . In one embodiment, the current sensor  320  comprises a ring or a coil. Furthermore, the current sensor  320  is positioned around and coupled to the power connection line  318  of the motor control system  310 . The output of the amplifier  322  is coupled to an input of the filter  324 . In one embodiment, the filter  324  is a low pass filter  332  which can be digital or analog. The output of the filter  324  is coupled to an input of the integrator  328 . The output of the integrator  328  is coupled to an analog-to-digital converter or to a threshold detector and timeout circuit  330 .  
         [0038]     The general use and operation of the motor control system  310  and the current detection system  311  will now be described with reference to  FIG. 3 . The user  110  initially approaches the treadmill exercise device  112  and steps onto the running belt  122  in front of the control panel  114 . The user  110  then programs the control panel  114  by entering information such as the weight of the user  110  and the speed at which the user  110  wishes to walk, jog or run. The circuitry inside the control panel  114  processes the information and raises the drive level line  316  to a calibrated current level corresponding to the amount of current that will be required by the motor  312 . The motor drive  314  amplifies the current from the drive level line  316  and provides an amplified current to the connection lines  318  which ultimately is received by the motor  312 . The motor  312  uses the amplified current and begins to rotate. This rotational energy is translated and reflected through gear and rollers (not shown) which ultimately rotate the running belt  122 . Thus, the magnitude of the current placed on the drive level line  316  by the circuitry of the control panel  114  controls the rotational speed of the running belt  122 .  
         [0039]     When the user  110  is walking, jogging or running on the treadmill exercise device  112 , each foot impact on the running belt  122  of the treadmill exercise device  112  causes an increase in the frictional force that is a function of the weight of the user  110  and the effective coefficient of friction between the running deck and the running belt  122 . The frictional force is applied to the treadmill exercise device  112  during each foot impact and results in a back electromotive force at the motor  312 . Accordingly, the motor  312  must work harder and, thus, consume more power to keep the running belt  122  moving at the same rate. The greater power consumption of the motor  312  corresponds to the increased current required by the motor  312  which is provided through the motor drive  314 .  
         [0040]     During each foot impact by the user  110 , the current requirements of the motor  312  increase which may be represented as a pulse  335  in a plot  334  of current verses time. When foot impacts are absent from the running belt  122 , then a plot  336  of the current requirements of the motor does not have pulses  335 . Thus, the pulses  335  are superimposed on the plot  336  to create the plot  334  of the overall current requirements of the motor  312  with respect to time.  
         [0041]     The pulses  335  are changes in current with respect to time and cause changes in the magnetic flux with respect to time around the connection lines  318  carrying the current pulses. These changes in magnetic flux with respect to time are detected in the current sensor  320  creating an induced electromotive force and accompanying induced current signal in the current detection system  311 . Accordingly, the current pulses in the motor control system  310  induce current pulses which form a current signal in the current detection system  311  as illustrated in plot  338 .  
         [0042]     The current signal propagates to the amplifier  322 . In one embodiment, the amplifier  322  is a transresistance amplifier which means that the input current signal is amplified and transformed into an output voltage signal. The output voltage signal, in one embodiment, propagates through a low pass filter  332  which may be digital or analog. The low pass filter  332  removes unwanted noise. The filter  324  is low pass since the range of foot-impact frequencies occurs at relatively low frequencies. The cutoff frequency of the low pass filter  332  should be determined so that the foot-impact frequency range passes through the filter  332 , but high frequency noise is removed from the signal. Another embodiment uses a bandpass filter to remove high and low frequency noise components without significant attenuation in the frequency range at which foot impacts occur.  
         [0043]     The filtered voltage signal is then integrated by the integrator  328 . The integrator periodically integrates the filtered voltage signal over a predetermined time duration. This time duration may be set by the manufacturer as a default time duration or can be a function of the actual or programmed speed of the running belt  122 . Other alternatives for determining the time duration were discussed above. An output signal from the integrator  328  represents an integration of the filtered voltage signal over the previous period of time in length equal to the time duration. Thus, the more foot impacts in a given time duration by the same user, then the larger the output signal from the integrator  328 .  
         [0044]     The signal can then be digitized by the analog-to-digital converter  330  as in one embodiment or sent directly to the threshold detector and timeout circuit  331  as in another embodiment. The threshold detector determines whether the output signal from the integrator  328  has dropped below a threshold value at which point the timeout circuit such as a resetable programmable counter is activated. The threshold value should preferably be set such that the threshold detector can distinguish between values from integrating signals containing noise and values from integrating signals containing pulses. In one alternative, the threshold value may factor in the weight or some other characteristic of the user  110  since a heavier user  110  would create greater pulses and thus larger output signals from the integrator  328 . In another alternative, the threshold value may also be a multiple of the value of the output signal from the integrator  328  when no foot impacts fall on the rotating running belt  122 .  
         [0045]     After the user  110  has stepped off the running belt  122  for a period of time, the output signal from the integrator  328  will drop below the threshold value. In one embodiment, the threshold detector then resets and enables the resetable programmable counter which then counts toward a programmed number representing a programmed time duration. If during the preset time duration of the counter, the output signal from the integrator  328  rises above the threshold value, as is the case when foot impacts from the user  112  commence again, then the threshold detector disables the resetable programmable counter. Accordingly, if the output signal from the integrator  328  again drops below the threshold value, the threshold detector would reset and enable the counter. If the counter reaches its programmed number representing the end of the programmed time duration, then the treadmill exercise device  112  automatically powers itself down.  
         [0046]     Although the foregoing invention has been described in terms of certain preferred embodiments, other embodiments will become apparent to those of ordinary skill in the art in view of the disclosure herein. Accordingly, the present invention is not intended to be limited by the recitation of preferred embodiments, but is intended to be defined solely by reference to the appended claims.