Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
  • A61B5/02438—Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient

Definitions

• This invention relates to a portable, preferably wrist-mounted, device for monitoring heartbeat or pulse rate.
• Various physical exercises and in particular those such as jogging which are practiced by individuals having widely varying ages and fitness factors, are beneficial only if performed within the range of levels which are reflected by the desired pulse rate of a given individual. If the individual's pulse rate does not rise to a particular lower level, the exercise may be of little effect whereas the effects can be decidedly harmful if an upper level is exceeded.
• a portable device for monitoring pulse rate comprising a sensor to be applied to the user's body at a point where the heartbeat pulse can be detected, a display unit to be mounted for convenient inspection by the user and electronic means to receive pulses from said sensor, relate said signals to a time base to produce rate signals, and transmit said rate signals to the display unit to be displayed as a pulse-rate readout.
• the invention envisions a wrist-type pulse monitor for providing a digital readout of the rate of a heartbeat comprising a sensor on said monitor adapted to detect a heartbeat in a region where a pulse normally occurs, a transducer coupled to said sensor for transforming each said detected heartbeat into an electrical signal, an oscillator for producing electrical pulses at a predetermined frequency, means coupled to said transducer and said oscillator for counting the number of said oscillator pulses occurring between detected heartbeats, arithmetic means coupled to said cotmting means for converting said counted oscillator pulses to a heartbeat rate and means for visually displaying said rate in digital form.
• FIG. 1 illustrates a front view of the novel wrist-mounted device for monitoring heartbeat rate
• Fig. 2 is a schematic representation of the reverse side of said wrist-mounted pulse or heartbeat monitor
• Fig. 3 is a schematic circuit representing the electrical circuit utilized in said wrist-mounted pulse monitor
• Fig. 4 illustrates various waveforms that appear in the circuit of Fig. 3
• Fig. 5 is a table illustrating the heartbeat rate, H, represented by the number of oscillator pulses, B, stored between heartbeats.
• the rate monitor includes a casing having the general form of a wrist watch which carries a sensor at its rear face in a position to contact a pulse point on the user's wrist and presents the heartbeat rate in digital form on the display unit on its front face and has a suitable strap provided to hold the casing to the wrist of the user with the sensor in its correct position.
• Fig. 1 illustrates the pulse rate monitor attached to the wrist of a user.
• the monitor comprises a casing 10 which is of substantially the same shape and size as the casing of a wrist watch and to which a wrist strap 11 is secured. Strap 11 is preferably formed of rubber or similar material to provide an effective grip on wrist 12 of the user and thus maintain the casing 10 in the desired position.
• a pressure sensor 13 of any well known type is mounted in the rear face of the casing 10 in such a position as to lie against the principal pulse point when casing 10 is strapped to wrist 12.
• the front of casing 10 carries a transparent screen 14 of a display unit which includes a numerical or digital readout.
• the readout can be a light emitting diode (LED) or a liquid crystal display (LCD) depending upon the type of power supply utilized and the amount of power that must be consumed by the display.
• the readout should present relatively large and easily read numerals.
• Casing 10 is also provided with a battery compartment 15 and contains electronic circuitry utilizing generally conventional components. As shown in Fig. 2, the circuitry comprises essentially a transducer 16 which receives pulse movements (caused by the heartbeat) from pressure sensor 13 and transmits corresponding electrical signals to a time base circuit 17 which produces a digital readout.
• the user will attach the casing 10 securely to his wrist as shown in Fig. 1 with the sensor 13 directly positioned at the proper pulse point and will then either have a direct readout or press an actuating button 18 to illuminate the display which presents a digital readout of his pulse rate.
• the display is of the LCD type, it may have continuous operation because of the low power requirement. Normal pulse rate is about 72 pulses per minute, and, depending upon the individual, exercise should be controlled to raise the rate to a higher value but not to exceed probably 120 pulses per minute. If the pulse rate is not raised enough, the exercise may be of little beneficial effect whereas it may be dangerous to exceed a particular rate, for example, 120 pulses per mimute, depending upon the individual.
• the user can monitor his progress by observing successive pulse rates over a period of time and by noting the time taken for his pulse to return to normal after completion of a particular exercise.
• Sensor 22 may be of any of the well-known types of pressure sensors which sense the pulse wave transmitted from the heart. Such a sensor is disclosed in U. S.
• Patent No. 3,838,684 The pressure pulse detected by sensor 22 is converted to an electrical signal in a well-known manner by transducer 24. Thus, for each heartbeat pulse detected by sensor 22, transducer produces an electrical output pulse. This pulse is coupled to a circuit which produces the digital readout representing heartbeat rate.
• the basic timing unit of the circuit is a 3600 Hz oscillator 28 as shown in Fig. 3.
• the heartbeat rate is determined by the formula
• a comparison of the heartbeat rate, H, and the number of pulses, B, which are stored between heartbeats based upon the above formula is shown in Fig. 5.
• a heartbeat rate, H of 60 beats per minute is represented.
• a heartbeat rate, H of 30 beats per minute is represented.
• the pulses that need to be stored between heartbeats ranges from 120 pulses to 20 pulses respectively. Therefore, with an average heartbeat of 72 beats per minute, each heartbeat occurs approximately every 0.83 seconds or, put another way, 1.2 heartbeats occur every second. This being the case, it is convenient to use a 60 Hz signal to represent the pulses being stored between heartbeats. Thus, if 60 pulses were stored between heartbeats, the arithmetic unit 80, in solving the equation set forth above, would divide 3600 by the 60 stored pulses to give a heartbeat rate of 60 beats per minute which, of course, is correct.
• Oscillator 28 produces its 3600 Hz signal on line 92 which is coupled to a clock circuit 94.
• Clock circuit 94 is a conventional clock circuit which stores signals representing seconds , minutes , and hours .
• the "seconds " are stored in a well known manner by dividing the input pulses to obtain 3600 seconds representing an hour.
• the "minute” register 96 however divides those 3600 pulses by 60 to obtain 60 pulses representing minutes and, of course, the "hour” register 97 divides the 60 pulses per minute by 60 to obtain hours .
• the output of clock circuit 94 on line 98 represents an output from a divider circuit producing 60 pulses per seqond.
• flip-flop 26 is a bistable multivibrator which changes states each time a pulse is received from transducer 24. Since transducer 24 produces a pulse each time a heartbeat is detected, flip-flop 26 is changing states each time the heart beats .
• flip-flop 26 is set in such an initial state that an output is produced on line 50 .
• This output is coupled through one-shot multivibrator 64 which produces a spike on its output line 66 which is coupled to storage counter register 48 as a clearing signal to clear the register 48.
• the output signal on line 50 from flip-flop 26 is also coupled via line 44 as an enabling signal to AND gate 36 .
• AND gate 36 now couples the 60 Hz signal on line 99 as an input to storage counter register 48 which begins to store the pulses therein.
• transducer 24 produces an output signal which changes the state of flip-flop 26 .
• the output on line 50 is removed thus removing the enabling signal to AND gate 36 on line 44 and producing an enabling signal on line 72 to AND gate 74 which also has as the other input thereto the output on line 76 of storage counter register 48.
• the input to storage counter regi ster 48 is removed and the output , the contents thereof , is coupled on line 76 through AND gate 74 on line 78 through OR gate 58 on line 60 to input register 62 .
• the pulses that were stored in storage counter regi ster 48 between heartbeats is now stored in input register 62 .
• the output of flip-flop 26 on line 52 is coupled as an enabling signal to AND gate 34 which, of course, has as its other input on line 30 , the 60 Hz signal .
• AND gate 34 which, of course, has as its other input on line 30 , the 60 Hz signal .
• the output of flip-f lop 26 on line 52 is coupled to one-shot multivibrator 68 which produces a spike on its output line 70 that clears storage counter register 42 .
• AND gate 34 therefore begins to pass the 60 Hz pulses on line 40 to storage counter register 42 for storage therein.
• the enabling signal has been removed from AND gate 54 and the contents of storage counter register 42 cannot be removed or gated therefrom.
• transducer 24 produced by the last heartbeat is coupled via conductor 84 through OR gate 86 on line 82 as an enabling signal to input register 62.
• the pulses stored in input register 62 from storage counter register 48 are gated on line 78 into the arithmetic unit 80. Since the arithmetic unit divides 3600 by the number of pulses stored between heartbeats, it produces a signal on line 88 which is coupled to display 90 representing the actual heartbeat rate.
• flip-flop 26 When the next heartbeat occurs, flip-flop 26 is reset and the enabling signal to AND gate 34 on line 38 is removed thus prohibiting further storage of any of the 60 Hz pulses on line 30 into storage counter register 42.
• an enabling signal on line 50 from flip-f lop 26 enables AND gate 54 thus allowing the contents of storage register 42 to be gated out on line 56 through AND gate 54 , OR gate 58 and line 60 to input register 62.
• storage counter register 48 is now enabled and begins storing the 60 Hz pulses.
• one of the counters 42 and 48 begins to store pulses from oscillator 28 until the next heartbeat is produced.
• the 60 Hz input pulses from clock circuit 94 are transferred from the first counter to the second counter while the output of the first counter is coupled to an input register 62 for storage purposes.
• the number of pulses occurring between heartbeats is stored alternately in counters 42 and 48 and transferred alternately to input register 62.
• a gating signal is required on line 82.
• This signal can be produced in any well known means but is produced in the preferred manner by coupling the output pulse from transducer 24 on line 84 to OR gate 86, line 82 and input register 62.
• the arithmetic unit 80 is programmed, as indicated earlier, to divide 3600 by whatever count or number of pulses is stored in input register 62.
• the arithmetic unit 80 will produce an output on line 88 which represents 180 heartbeats per minute and this output is coupled to display 90 where it is displayed in numerical form.
• the arithmetic unit 80 will produce an output on line 88 representing 72 heartbeats per minute which will be displayed by display 90 in numerical form.
• a circuit is shown in Fig. 3.
• the output of oscillator 28 on line 92 is coupled to a clock circuit 94.
• Clock circuit 94 has registers for developing signals representing seconds, minutes and hours.
• a "heartbeat" register in clock 94 could divide the input signal and store 60 pulses per second.
• 60 pulses per second were to be stored in a register representing upper or lower limits, the user would not be able to accurately determine when the desired number of pulses has been stored because 60 pulses would occur in just one second.
• the output of the "heartbeat" register on line 98 is coupled to a divider circuit 100 which, divides the number of pulses being received by any convenient number but, in the preferred example, by three which would enable the output of divider circuit 100 to be twenty pulses per second on line 102.
• the output of divider circuit 100 on line 102 may be coupled either to switch 19 or to switch 20. If switch 19 is actuated, it couples the 20 pulses per second on line 102 to storage register 104 which stores pulses representing the predetermined upper limit heartbeat rate desired. If switch 20 is actuated, the pulses from divider circuit 100 on line 102 are coupled to register 106 which stores pulses representing the predetermined lower limit heartbeat rate desired.
• Switches 19 and 20 are so arranged with switch 23 coupled to the input of counters 42 and 48 that whenever either switch 19 or 20 is actuated, switch 23 is opened to remove the output of oscillator 28 to the counter circuits.
• Separate switches could, of course, be used. The reason that this is necessary is to be able to utilize the slower occurring pulses (i.e., 20 pulses per second) from divider circuit 100 as the reference source in order to be able to visually observe the display while physically depressing switch 19 or switch 20 until the proper heartbeat rate is reached.
• switch 19 if switch 19 is actuated, thereby coupling the output of divider circuit 100 to register 104, it also opens switch 23 to prevent the output from the "heartbeat" register from going to the counter circuits 42 or 48 and also couples the pulses from divider circuit 100 through. OR gate 108 on line 110 to OR gate 58 which produces an output on line 60 to input register 62.
• the same pulses that are being stored in register 104, the register storing pulses representing the predetermined upper limit or heartbeat rate are being coupled to the arithmetic unit 80 for processing so that the display 90 will read directly the heartbeat rate represented by the pulses being stored in register 104.
• switch 19 or switch 20 when switch 19 or switch 20 is depressed to set the predetermined upper or lower limits of heartbeat rate, it is desirable that no pulses be present from counters 42 and 48. Thus, switch 23 is opened each time either switch 19 or switch 20 is closed, thus preventing any storage through the counting circuit. However, it is necessary that input register 62 be gated at some interval so that the pulses being stored therein may be coupled in a group or unit to the arithmetic unit 80.
• switch 112 may couple power source 114 to a monostable multivibrator 116 that produces an output on line 118 at predetermined intervals which is coupled by OR gate 86 on line 82 as a gating signal to input register 62.
• Multivibrator 116 may be designed in a well known manner to oscillate at any predetermined frequency, for instance, 10 cycles per minute (every six seconds) which would allow a maximum of 120 pulses (6 x 20) to be stored in input register 62 between gating pulses. At that rate, 120 stored pulses in input register 62 would represent a heartbeat of 30 beats per minute. That heartbeat rate is probably as low as one would want to check or set for a predetermined lower limit. However, multivibrator 116 could be adjusted to any desired frequency to provide a gating signal on line 82 for input register 62.
• the output from input register 62 on line 78 is not only coupled to the arithmetic unit 80 but is also coupled through conductor 120 to comparators 122 and 124. If the number of pulses stored in input register 62 representing the actual heartbeat is greater than the number of pulses stored in register 104, comparator 122 produces an output signal on line 126 which passes through OR gate 128 to alarm 130 which may be an audible alarm to warn the user.
• comparator 124 produces an output signal on line 132 which also passes through OR gate 128 to activate alarm 130.
• the user may set a predetermined high heartbeat rate and a low heartbeat rate which, if the actual heartbeat rate exceeds the upper limit or does not reach the lower limit, will cause an alarm to be activated and the user alerted.
• clock unit 94 already provides seconds, minutes and hour signals based upon a division of the pulses that it receives from oscillator 28, it is a simple matter to couple those signals on conductor 134 to switch 25 which may selectively couple either the output of the clock circuit 94 which continuously maintains time or the output of arithmetic unit 88 to display 90.
• switch 25 may selectively couple either the output of the clock circuit 94 which continuously maintains time or the output of arithmetic unit 88 to display 90.
• the pulse monitor While the pulse monitor is not being used as a pulse monitor it may be utilized as a clock or watch s ⁇ mply by placing switch 25 in the appropriate position.
• Fig. 4 illustrates the various waveforms that appear at particular points in the circuit shown in Fig. 3.
• Graph A illustrates the electrical pulses produced by transducer 24 as each heartbeat is detected by sensor 22.
• Graph A shows, as an example only, the electrical pulses getting closer together with time indicating that the heartbeat rate is increasing.
• Graph B illustrates the 60 Hz pulses from clock circuit 94 which are being stored in one of the storage counter registers 42 or 48. Assume, that 50 pulses were stored in storage counter register 42 during the interval between pulses 136 and 138 representing an interval between the heartbeats, of the user.
• Fifty pulses, as shown in Fig. 5, represents 72 heartbeats per minute, the average heartbeat of an individual.
• flip-flop 26 again changes state thus causing the 60 Hz pulses from clock circuit 94 to again be stored in counter register 42 while those pulses previously stored in counter 48 as shown in graph C are gated out again to the input register 62 as shown in graph B. This time, however, there are only 48 pulses stored in input register 62. Although not shown in the table in Fig. 5, the heartbeat rate can be calculated from the formula previously given and shown to be 75 beats per minute. Thus, the heartbeat rate is increasing.
• electrical pulse 142 again flip-flop 26 changes states thus causing the 60 Hz pulses from clock circuit 94 to be stored in counter 48 and those pulses stored previously in counter 42 are gated out to input storage register 62.
• the present invention has several advantages over the prior art devices.
• predetermined high and low heartbeat rate limits may be set which, if the actual heartbeat rate exceeds or does not reach, activates an alarm to warn the user.
• these upper and lower predetermined limits are easily set by the user simply depressing an upper limit key or a lower limit key and then reading the display output until the proper predetermined limit is reached and then releasing the button or key.
• the unit can be economically used as a wrist watch inasmuch as a clock circuit already exists within the unit.

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• 1979
  • 1979-11-08 IT IT7950785A patent/IT1162436B/it active
  • 1979-11-09 JP JP50209879A patent/JPS55501167A/ja active Pending
  • 1979-11-09 WO PCT/US1979/000962 patent/WO1980000912A1/en unknown
• 1980
  • 1980-05-20 EP EP19790901644 patent/EP0020643A4/en not_active Withdrawn
• 1984
  • 1984-04-17 SG SG308/84A patent/SG30884G/en unknown
  • 1984-08-23 HK HK656/84A patent/HK65684A/xx unknown

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