Abstract:
The present invention offers a heart pulse detector. Two pairs of contact electrodes mounted on each handrail of treadmill separately. A electrocardiography heart pulse detector built in the control panel of the treadmill has input terminal which electrically connected to the contact electrodes. A front end circuit within the heart pulse detector receives the electrical cardio signals of a user from the input terminal and preprocesses the electrical cardio signals for later processing by the reminder functional blocks of the heart pulse detector. A hand touching detection circuit assembly in the heart pulse detector is also connected to the input terminal. The hand touching detection circuit sense the signals from the input terminal and send out hand on/off data for using to control the speed of the treadmill and to control the operation of the heart pulse detection.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a heart pulse detector, and more particularly to a heart pulse detector which detects a user&#39;s heart pulse signal as well as the touching action style of the user&#39;s hands via the same contact electrodes and outputs heart pulse data and hand touch signals for controlling the speed of a treadmill accordingly. 
         [0003]    2. Description of the Related Art 
         [0004]    For electrical treadmill with electrocardiography heart pulse monitor needs contact electrodes which are usually mounted on the handrails of treadmill to derive the electrical cardio signals from the user when the hands of the user grasp or touch on the electrodes. In some cases, there may be circuits in the heart pulse monitor to sense the presence of the user&#39;s hands contacting with the electrodes and then to control the operation of functions of heart pulse monitor itself only. 
         [0005]    For conventional electrical treadmill, there should have an extra apparatus to provide a user input means for user to input the commands to control the speed of the treadmill when the user is running or walking on it. There are varieties of user input apparatus for using to control the speed of a treadmill. For example, keypad or key switches are commonly user input apparatus for speed control of a treadmill. The technology is used in U.S. Pat. No. 6,830,541, to Wu, the system uses this technology consists of at least a movable switch mounted on an arm of the main flame and includes a holder secured on the arm. Some other examples are using different kind of sensors such as contact switch to sense the touching of user and control the speed of a treadmill. For example, the U.S. Pat. No. 6,761,688, to Chang, the system use one contact switch mounted on a corresponding one of the arms of the treadmill to cause an analog signal to control the speed. Some other sensors are using photoelectric device to sense the motion of hands of a user or the position of a user and generate commands to control the speed of treadmill. For example, the U.S. Pat. No. 6,135,924, to Gibbs, et al, the system use an optical sensor monitors the position of a user on the treadmill and automatically varies the speed of the treadmill. Some other sensors are using ultrasonic device to sense the motion of hands of user or the position of user and generate commands to control the speed of a treadmill. For example, the U.S. Pat. No. 6,719,668, to Huang, the system use two ultrasonic transmitter receiver units respectively installed in the upright support of the house flame at two sides. Another example is the U.S. Pat. No. 5,368,532, to Farnet, the system use sensors located below an upper run of the belt for sensing the position of a user, and a controller for controlling the speed of the belt in accordance with the position of the user relative to the sensors, causing the belt to accelerate, decelerate. 
         [0006]    All extra apparatus mentioned above for speed control of treadmill increase the complexity of manufacture and then increase the cost of treadmill. 
       OBJECTS OF THE INVENTION 
       [0007]    It is therefore an object of the invention to provide a heart pulse detector which detects a user&#39;s heart pulse signal as well as the touching action style of the user&#39;s hands via the same contact electrodes and outputs heart pulse data and hand touch signals for controlling the speed of a treadmill accordingly, thus simplify the manufacture of treadmill and save the cost of treadmill. 
       DISCLOSURE OF THE INVENTION 
       [0008]    A first aspect of the present invention teaches a heart pulse detector used in a treadmill that including a base frame, a motor driven tread belt, a rightup frame with a left handrail and a right handrail, a control panel, the heart pulse detector including: A plurality of sensor on the left handrail and the right handrail for obtaining electro cardio signal from the user; An instrument amplifier for amplifying the electro cardio signal; A common circuit for providing a common reference voltage to the instrument amplifier; A heart pulse detector for detecting a heart pulse signal in response to the amplified electro cardio signal from the output of the instrument amplifier and for producing a digital pulse that is synchrony with the heart pulse signal and is transmitted to the microprocessor in the control panel for calculating the heart pulse rate of the user; A plurality of sensor comprising a first pair of contact electrodes and a second pair of contact electrodes; The first pair of contact electrodes comprising a first contact electrode and a second electrode mounted on the left handrail of the treadmill separately; The second pair of contact electrodes comprising a third contact electrode and a fourth electrode mounted on the right handrail of the treadmill separately; The first contact electrode and the third contact electrode being connected to the inputs of the instrument amplifier; The second contact electrode and the fourth electrode being connected to the output of the common circuit; A hand touch detection circuit for receiving the signals from the first contact electrode and the third contact electrode and for producing a plurality of hand touch signal to indicate whether the first pair of contact electrodes and/or the second pair of contact electrodes are touching with the hand of the user; A plurality of hand touch signal will be transmitted to the microprocessor in the control panel for performing the speed control of the treadmill; The common circuit will output a high level voltage when a plurality of hand touch signal indicate that the first pair of contact electrodes and second pair of contact electrodes are not touching with the hand of the user. 
         [0009]    Another preferred embodiment of the present invention teaches a hand touch detection circuit consist a data encoder for converting a plurality of hand touch signal into a formatted serial data signal for transmitting to the microprocessor in the control panel for performing the speed control of the treadmill. 
         [0010]    The hand touch detection circuit further consists: A first inverter for responding to the signal at the first contact electrode and providing a first left input signal; A first comparator for responding to the signal at the first contact electrode and providing a second left input signal; A second inverter for responding to the signal at the third contact electrode and providing a first right input signal; A second comparator for responding to the signal at the third contact electrode and providing a second right input signal; A circuit for providing reference voltage to the positive input of the first comparator and the positive input of the second comparator; A processor for responding to the first left input signal, the second left input signal, the first right input signal, the second right input signal and providing a first hand touch signal to indicate whether only the first pair of contact electrodes are touching with the hand of the user and providing a second first hand touch signal to indicate whether only the second pair of contact electrodes are touching with the hand of the user and providing a third hand touch signal to indicate whether the first pair of contact electrodes and second pair of contact electrodes are touching with both hands of the user at the same time. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The foregoing and other advantages of the invention will be more fully understood with reference to the description of the best embodiment and the drawing wherein: 
           [0012]      FIG. 1  is a perspective view of a treadmill constructed according to the present invention. 
           [0013]      FIG. 2  is a block diagram of the present invention. 
           [0014]      FIG. 3  is a block diagram of hand touch detector of the present invention. 
           [0015]      FIG. 4  is a block diagram of hand touch processor of hand touch detector of the present invention. 
           [0016]      FIG. 5  is a block diagram of common driver of the present invention. 
           [0017]      FIG. 6  is a flow chart illustrating the operation of hand touch processor of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The foregoing and other advantages of the invention will be more fully understood with reference to the description of the best embodiment and the drawing as the following description. 
         [0019]    The preferred embodiment of present invention is illustrated in  FIGS. 1-6 . 
         [0020]    As shown in  FIG. 1 , a treadmill  1  comprises a bass frame  2  having a tread belt  3  which is driven by a motor mounted in the bass frame  2 . A pair of upright frame members  4  on the head side of the base frame  2  support a control panel  5  at an upper portion of the upright frame members  4 , a left handrail  6  and a right handrail  7  are mounted on a respective side thereby. A pair of contact electrodes  11 ,  12  are mounted on the left handrail  6  by a holder  8 . Another pair of contact electrodes  13 ,  14  are mounted on the right handrail  7  by a holder  9 . 
         [0021]    Referring to  FIG. 2 , a heart pulse detector circuitry  10  includes a hand touch detector  31 , a common driver  32 , an instrument amplifier  33 , a band-pass filter  34 , a low-pass filter  35 , a peak detector  36 , and a one-shot circuit block  37 . 
         [0022]    The contact electrode  11  and the contact electrode  14  are electrically connected together to terminal  21  which is connected to the output of the common driver  32  and also is connected to the common input of the instrument amplifier  33 . The contact electrode  12  is electrically connected to terminal  22  which is connected to one of the inputs of the instrument amplifier  33  and also is connected to one of the inputs of the hand touch detector  31 . The contact electrode  13  is electrically connected to a terminal  23  which is connected to other input of the instrument amplifier  33  and is also connected to the other input of the hand touch detector  31 . 
         [0023]    The detail circuits of the hand touch detector  31  are shown in  FIG. 3 . The input of the hand touch detector  31  which connected to terminal  22  is connected to an input of inverter  66  and to a negative input of a comparator  68  and to one of the terminals of a resistor  64 . The other input of the hand touch detector  31  which connected to terminal  23  is connected to the input of an inverter  67  and to the negative input of a comparator  69  and to one of the terminals of a resistor  65 . The other terminal of both resistor  64  and resistor  65  are both connected to the ground. In order to keep high impedance at terminal  22  and terminal  23 , the prefer value of the resistor  64  and the resistor  65  is 10M ohm each. The positive inputs of the comparator  68  and the comparator  69  are both connected to a reference voltage terminal  71  which is derived from the resistor  62  and the resistor  63 . The output of the inverter  66  is connected to terminal  72  and is named as “L-INPUT A”. The output of the inverter  67  is connected to terminal  73  and is named as “R-INPUT A”. The output of the comparator  68  is connected to terminal  74  and is named as “L-INPUT B”. The output of the comparator  69  is connected to terminal  75  and is named as “R-INPUT B”. Terminals  72 ,  73 ,  74 ,  75  are connected to the inputs of a hand touch processor  81 . One of the outputs of the hand touch processor  81  which connected to terminal  24  is used to control the operation of the heart pulse detection. The other output of the hand touch processor  81  which connected to terminal  25  is used to send out the data of events of hand touch for speed control of the treadmill. 
         [0024]    As shown in  FIG. 4 , the hand touch processor  81  includes an events detector  91 , a timer  92 , and an events encoder  93 . The events detector  91  analyze the input signals from terminals  72 ,  73 ,  74 ,  75  and combine with the control of the operation of the timer  92 , then sent out the signals of events of hand touch through terminals  94 ,  95 ,  96  to the inputs of the events encoder  93 . Terminal  94  is the event signal of “BOTH HAND”. Terminal  95  is the event signal of “LEFT HAND”. Terminal  96  is the event signal of “RIGHT HAND”. The detail operation of the events detector  91  is shown in  FIG. 6  by a logic flow chart. One output of events encoder  93  come from buffer of terminal  94  and is connected to terminal  24 . The other output is encoded serial data of events of hand touch and is connected to terminal  25 . The prefer embodiment of events encoder  93  is a three bits Manchester code encoder. There are six event data and named as “LEFT HAND ON”, “LEFT HAND OFF”, “RIGHT HAND ON”, “RIGHT HAND OFF”, “BOTH HAND ON”, and “BOTH HAND OFF”. Referring to  FIG. 2 , as the microprocessor  52  receives the data of events of hand touch from terminal  25 , then speed controller  53  or incline controller  54  will receives command sent by microprocessor  52  and the speed or incline of the treadmill is adjusted. 
         [0025]    As shown in  FIG. 5 , the common driver  32  is built by an operational amplifier  45 . The positive input of operational amplifier  45  is connected to a reference voltage terminal  49  which is derived from a resistor  42  and a resistor  43 . The output and the negative input of the operational amplifier  45  are connected together and are connected to a switch  46  and terminal  21 . The signal of terminal  24  controls the operation of the common driver  32 . When the state of terminal  24  is at logic low, switch  41  and the operational amplifier  45  are turn off and switch  46  is turn on, then a high level voltage is output to terminal  21 . When the state of terminal  24  is at logic high, switch  41  and operational amplifier  45  are turn on and switch  46  is turn off, then a level of half supply voltage (i.e. ½ VCC) is output to terminal  21 . 
         [0026]    At the start of the heart pulse detector circuitry  10  after power on or function is enable, all the state of terminals  94 ,  95 ,  96  are set to off (logic low). So the state of terminal  24  is at logic low and the common driver  32  outputs a high level voltage to terminal  21 . 
         [0027]    When all the contact electrodes  11 ,  12 ,  13 ,  14  are not touched by user&#39;s hand, then the signals at terminals  22 ,  23  are both at low voltage level. The states of terminal  72 ,  73  are both at logic high, thus there is no state changed at terminals  94 ,  95 ,  96 . 
         [0028]    When the contact electrodes  11 ,  12  are touched by a user&#39;s hand, then a high level voltage is conducted to terminal  22  from terminal  21  through contact electrodes  11 ,  12  and the user&#39;s hand. The state of terminal  72  is then changed to logic low and timer  92  is started by events detector  91 . As the user&#39;s hand keep in touch with contact electrodes  11 ,  12  for period larger than a timing T2 (for example, 100 msec), then the state of terminal  95  is set to logic high and a “LEFT HAND ON” signal is sent out to terminal  25 . When the user&#39;s hand moves out the contact electrodes  11 ,  12 , then signal on terminal  22  goes down to low voltage and the state of terminal  72  comes back to logic high. Timer  92  will be started again by events detector  91 . After a timing T3 (for example, 100 msec) has been passed, the state of terminal  95  is set to logic low and a “LEFT HAND OFF” signal is sent out to terminal  25 . 
         [0029]    When the contact electrodes  13 ,  14  are touched by the user&#39;s hand, then a high level voltage is conducted to terminal  23  from terminal  21  through contact electrodes  13 ,  14  and the user&#39;s hand. The state of terminal  73  is then changed to logic low and the timer  92  is started by the events detector  91 . As the user&#39;s hand keep in touch with the contact electrodes  13 ,  14  for a period larger than a timing T2 (for example, 100 msec), then the state of terminal  96  is set to logic high and a “RIGHT HAND ON” signal is sent out to terminal  25 . When the other user&#39;s hand touch on the contact electrodes  11 ,  12  following, the state of terminal  72  now is changed to logic low, then the events detector  91  set the timer  92  start. As this state continue for a timing T1 (for example, 200 msec), the state of terminal  96  is set to logic low and a “RIGHT HAND OFF” signal is sent out to terminal  25 . Following, then both the state of terminals  94 ,  24  are set to logic high and a “BOTH HAND ON” signal is sent out to terminal  25 . 
         [0030]    Referring to  FIG. 3 , as there is logic high state at terminal  24 , the switch  61  and the comparators  68 ,  69  are turn on. The voltage at terminal  71  will be far below half of the supply voltage by let the value of resistor  63  far larger than the value of the resistor  62 . So both the state of terminals  74 ,  75  is held at logic low when the voltages at terminals  22 ,  23  are conducted to the level of half supply voltage. Then the states of terminals  94 ,  24  are kept unchanged. 
         [0031]    Referring to  FIG. 2 , as the state of terminal  24  is at logic “high”, all the functional blocks in the heart pulse detector  10  are turn on. The electrical cardio signals derived from the user&#39;s hands through the contact electrodes  11 ,  12 ,  13 ,  14  are conducted to the inputs of the instrument amplifier  33  via terminals  21 ,  22 ,  23 . The output of the instrument amplifier  33  is connected to the input of the band-pass filter  34  which extracts the so call “R” wave signal from the electrical cardio signals. The output of band-pass filter  34  is connected to the input of the low-pass filter  35  which will filter out the noise whose frequency is higher than the “R” wave signal. The filtered “R” wave signal then come into the peak detector  36  and the peak signal of the “R” wave signal is picked out thereby. When the peak signal of the “R” wave signal is sent into the one-shot circuit  37 , a one-shot heart pulse signal is output to terminal  26  and input to the microprocessor  52 . After receives a sequence of one-shot heart pulse signals from terminal  26 , the microprocessor  52  will perform the processing and counting to calculate out the real heart pulse rate of the user and shows the result at display  55 . 
         [0032]    When the user release one hand or both hands from the contact electrodes  11 ,  12  or/and the contact electrodes  13 ,  14  for a period longer than timing T4 (for example, 200 msec.), both the state of terminals  94 ,  24  are set to logic high and a “BOTH HAND OFF” signal is sent out to terminal  25 . Then the function of heart pulse detection is turn off and the microprocessor  52  will stop the calculation of heart pulse rate of the user. As one of the user&#39;s hand continuing touches on the contact electrodes  11 ,  12  or the contact electrodes  13 ,  14 , the state of terminal  95  or terminal  96  is not changed and no more data of events of hand touch will be sent out to terminal  25 . Only when both of the user&#39;s hands are moved out from the contact electrodes  11 ,  12 ,  13 ,  14 , the events detector  91  will go back to its initial state. 
         [0033]    The heart pulse detector of the present invention can be used as a user input apparatus to control the speed of treadmill. It is also can be used as a user input device to change the operation mode of treadmill or to control incline angle of treadmill. 
         [0034]    Although specific embodiments of the invention have been disclosed, it will be understood by those having skill in the art that minor changes can be made to the form and details of the specific embodiments disclosed herein, without departing from the scope of the invention. The embodiments presented above are for purposes of example only and are not to be taken to limit the scope of the appended claims.