WRIST-TYPE PULSE MONITOR

APPAREIL DE CONTROLE DU POULS RADIAL

English Abstract

WRIST-TYPE PULSE MONITOR
Abstract of the Disclosure
The present invention relates to a wrist-type
pulse monitor for providing a digital readout of the rate
of a heartbeat. The monitor is comprised of a sensor
adapted to detect a heartbeat in a body region where a
heartbeat pulse normally occurs. A transducer is coupled
to the sensor for transforming each detected pulse into an
electrical signal. An oscillator produces electrical
pulses at a predetermined frequency. A counter is coupled
to the transducer and the oscillator for counting the
number of oscillator pulses occurring between detected
heartbeats. An arthimetic unit is coupled to the counter
for converting the counted oscillator pulses to a heartbeat
rate. A display is provided for visually displaying the
heartbeat rate in digital form.

Claims

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined as
follows:
1. A wrist-type pulse monitor for providing a
digital read out of the rate of a heartbeat comprising:
(a) a sensor adapted to detect a heartbeat, in a
region where a heartbeat pulse normally occurs,
(b) a transducer coupled to said sensor for
transforming each said detected heartbeat into an
electrical signal,
(c) means for producing electrical pulses at a
predetermined frequency,
(d) means coupled to said transducer and said
pulse producing means for counting the number of said
produced pulses occurring between two consecutively
detected heartbeats, said pulse counting means comprising:
(i) first and second counters coupled to said
pulse producing means and said transducer for
alternately counting said pulses between
heartbeats,
(e) arithmetic means for converting said counted
pulses to a heartbeat rate,
(f) means for alternately coupling the outputs of
said counters to said arithmetic means whereby the
contents of one counter is converted to heartbeat rate
while the other is storing said pulses between detected
heartbeats, and
(g) means coupled to said arithmetic means for
visually displaying said rate in digital form whereby a
continuous heartbeat rate is displayed.
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2. A pulse monitor as in claim 1 wherein said
pulse producing means includes:
(a) an oscillator having a frequency of 3600
hertz, and
(b) clock circuit means for reducing said
oscillator frequency to 60 Hz for maintaining time of day
in hours, minutes and seconds.
3. A pulse monitor as in claim 2 wherein said
arithmetic means comprises:
(a) means for converting said counted 60 Hz
pulses to heartbeat rate in accordance with the formula
<IMG>
where H = heartbeat rate and B = number of 60 hertz pulses
counted between heartbeats.
4. A pulse monitor as in claim 3 further including:
(a) means for establishing an upper and lower
predetermined heartbeat rate limit,
(b) means coupled to said limit establishing means for
providing a warning signal when said actual heartbeat rate
is below said lower predetermined rate limit and higher
than said upper predetermined rate limit, and
(c) alarm means coupled to said signal producing means
for generating an alarm indication when said warning
signal is produced.
5. A pulse monitor as in claim 4 wherein said means
for establishing upper and lower predetermined heartbeat
rate limits comprises:
(a) first and second pulse storage registers
respectively,
(b) pulse divider means for further reducing the
17

frequency of said 60 Hz pulses to a lower predetermined
frequency, and
(c) means coupled to said pulse divider means, said
first and second pulse storage registers and said
arithmetic means for simultaneously storing a
predetermined number of said reduced frequency pulses in a
selected one of said registers representing said upper and
lower heartbeat rate limits and calculating and displaying
the instantaneous heartbeat rate represented by said
stored pulses.
6. A pulse monitor as in claim 5 wherein said warning
signal producing means comprises:
(a) first and second comparators each having one input
coupled to said first and second pulse storage registers
respectively and the other input coupled to said counting
means whereby if the output of said counting means
representing the actual number of 60 Hz pulses occurring
between heartbeats is greater than the number of pulses
stored in said first register or less than the number of
pulses stored in said second register, a warning signal is
produced by the corresponding comparator.
7. A pulse monitor as in claim 6 wherein said means
for storing a predetermined number of pulses in said first
and second pulse storage registers comprises:
(a) switch means coupled to said pulse divider means
and said first and second pulse storage registers for
selectively coupling said reduced pulses to a predetermined
one of said storage registers, and
(b) means for coupling said selected reduced number of
output pulses to said arithmetic means whereby said display
indicates the heart rate represented by the count being stored
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in said selected first or second pulse storage register.
8. A pulse monitor as in claim 7 further including:
(a) means for disconnecting the output of said clock
circuit to said counting means whenever said switching
means for selectively storing pulses in said first and
second storage registers is actuated.
9. A pulse monitor as in claim 3 further comprising
switch means for selectively coupling the output of said
clock circuit and said arithmetic means to said display
unit whereby either time of day or heartbeat rate may be
selectively displayed.
10. A pulse monitor comprising:
(a) a body portion adapted to be attached to and worn
about the wrist with a strap,
(b) a sensor mounted in said body portion for
detecting a heartbeat,
(c) a transducer coupled to said sensor for producing
an electrical signal for each detected heartbeat,
(d) a source of electrical pulses of predetermined
frequency,
(e) first and second storage means alternately coupled
to said pulse source and said transducer for storing only
said pulses occurring between electrical signals from said
transducer representing successive heartbeats,
(f) arithmetic means alternately coupled to said first
and second storage means for converting said stored pulses
occurring only between each two successive heartbeats to a
heartbeat rate, and
(g) display means coupled to said arithmetic means for
visually displaying said rate.
19

Description

9470
Background of the Invention
This invention relates to a portahle, preferably
wrist-mounted, device for monitoring heartbeat or pulse
rate. Vario~ls 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 leve]s 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.
Prior art devices exist which monitor the beat of
the human heart such as the monitor disclosed in U.S.
Patent No. 3,742,937. However, in that particular case, a
visible light pulse is produced for each heartbeat
measured during a fifteen second interval. Thus, once the
light begins flashing, the flashing will continue for
fifteen seconds and the user of the monitor must count the
flashes from the light and multiply by four to obtain his
present heart rate in beats per minute. A readout is, of
course, extremely inconvenient to obtain and is subject to
error in that the ùser may either miscount the flashes of
light or make a mistake in multiplying the number of
flashes times four and, thus, may obtain the incorrect or
improper heart rate.
Summary of the Invention
In accordance with an aspect of the invention
there is provided a wrist-type pulse monitor for providing
a digital read out of the rate of a heartbeat cornprising:
(a) a sensor adapted to detect a heartbeat, in a region
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where a heartbeat pulse normally occurs, (b) a transducer
coupled to said sensor for transforming each said detected
heartbeat into an electrical signal, (c) means for
producing electrical pulses at a predetermined frequency,
(d) means coupled to said transducer and said pulse
producing means for counting the number of said produced
pulses occurring between two consecutively detected
heartbeats, said pulse counting means comprising: (i)
first and second counters coupled to said pulse producing
means and said transducer for alternately counting said
pulses between heartbeats, (e) arithmetic means for
converting said counted pulses to a heartbeat rate, (f)
means for alternately coupling the outputs of said
counters to said arithmetic means whereby the contents of
one counter is converted to heartbeat rate while the other
is storing said pulses between detected heartbeats, and
(g) means coupled to said arithmetic means for visually
displaying said rate in digital form whereby a continuous
heartbeat rate is displayed.
It is an object of the present invention to
provide a simple device which gives a convenient and
direct readout of the effects of physical exercises such
as jogging on the heartbeat or pulse rate. According to
the present invention, there is provided 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 p~lses 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.
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Thus, 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 trans-
forming 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 counting means for
converting said counted oscillator pulses to a heartbeat
rate and means for visually displaying said rate in
digital form.

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13RIEF DESCRII'~'ION OF T~ Dl?/~ IN(`S
Numerous other aspects of this invention along with
3 additional ob~ectives, features, and advanta~es of the invention
4 shoul~ now become apparent upon a readinq of the followinq
e~l-osit:ion ;n conjnnction wit:h the aCcom~ ny~ drlwin(ls in wilich:
6 FIGU~ 1 illustrates a front view of the novel wrist-
7 mounted device for monitoring heartbeat rate.
8 i FIGUR~ 2 is a schematic representation of the reverse
9 side of said wrist-mounted pulse or heartbeat monitor.
FI~7UR~ 3 is a schematic circuit representing the
11 electrical circuit utilized in said wrist-mounted pulse monitor.
12 FIGURE 4 illustrates various waveforms that appear in
13 the circuit of FI~,UP~ 3.
14 FIGURE 5 is a table illustrating the heartbeat rate, ~1,
15 represented by the number of oscillator pulses, ~, stored between
16 heartbeats.
17 DETAILED DESCRIPTION OF THE DRAWI~IGS
.
18 Preferably, the rate monitor includes a casing having
19 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
21 wrist and presents the heartbeat rate in digital form on the
22 display unit on its front face and has a suitable strap provided
23 to hold the casing to the wrist of the user with the sensor in
24 its correct position. FIGURE 1 illustrates the pulse rate monitor
25 attached to the wrist of a user. As can be seen, the monitor
26 comprises a casing 10 which is of substantially the same shape
27 and size as the casing of a wrist watch and to which a wrist
28 strap 11 is secured. Strap 11 is preferably formed of rubber or
29 similar material to provide an effective grip on wrist 12 of the
user and thus maintain the casing 10 in the desired position. A
31 pressure sensor 13 of any well known type is mounted in the rear

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1 face of the casing 10 in such a position as to li~ aqainst the
2 principal pulse point when casing lO is strapped to w~ist 12.
3 q`he front of casing 10 carries a transparent screen 1~ of a
4 display unit which includes a numerical or digital readout. *he
readout can be a light emitting diode (LED) or a liquid crystal
6 display (LCD) depending upon the type of power supply utilized
7 and the amount of po~er that must be consumed by the dis~lay.
8 The readout should present relatively large and easily read
9 numerals. Casing 10 is also provided with a battery compartment
15 and contains electronic circuitry utilizing generally conven-
11 tional components. As shown in FIGURE 2, the circuitry compxises
12 essentially a transducer 16 which receives pulse movements (caused
13 by the heartbeat) from pressure sensor 13 and transmits corres-
14 ponding electrical signals to a time base circuit 17 which produces
a digitalreadout.
16 In actual operation, the user will attach the casing 10
17 securely to his wrist as sho~n in FI~,URE 1 with the sensor 13
18 directly positioned at the proper pulse point and will t:hen either
19 have a direct readout or press an actuating button 18 to illu~i-
nate the display which presents a digital readout of his pulse
21 rate. If the display is of the LCD type, it may have continuous
22 operation because of the low power requirement. ~lormal pulse
23 rate is about 72 pulses per minute, and, depending u~on the
24 individual, exercise should be controlled to raise the rate to a
higher value but not to exceed probably 120 pulses per minute.
26 If the pulse rate is not raised enough, the exercise may be of
27 little beneficial effect whereas it may be dangerous to exceed a
28 particular rate, for example, 120 pulses per minute, depending
29 ~ upon the individual. Also, the user can monitor his progress by
observing s~ccessive pulse rates over a period of time and by
31 noting the time taken for his pulse to return to nor~al af~er
32 completion of a particular exercise.

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A novel circuit for producing a digital readout of
the heartbeat rate is disclosed in FIGURE 3. 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, the transducer produces an
electrical output puIse. 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 FIGURE 3. The heartbeat rate per minute is
determined by the formuIa
H = 3600
where 3600 is simply a unit number, H = heartbeat rate per
minute; and B = the number of 60 Hz puIses stored between
heartbeats. A comparison of the heartbeat rate, H, and the
number of puIses, B, which are stored between heartbeats based
upon the above formuIa is shown in FIGURE 5. Thus, if 60
pulses are stored between heartbeats, a heartbeat rate, H, of
~0 beats per minute is represented. In like manner, if 120
pulses are stored between heartbeats, a heartbeat rate, H, of
30 beats per minute is represented. Thus, for a range of
heartbeat rate from 30 to 180 heartbeats per minute, 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

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60 Hz signal to represent the pulses, B, 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.
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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 with registers which store
signals representing seconds, minutes, and hours. The "seconds",
of course, 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. Thus, the output of clock circuit 94 on
line 98 represents an output from a divider circuit producing
60 pulses per second. These pulses are coupled via conductor
99 through switch 23 and conductors 30 and 32 to AND gates 34
and 36. AND gates 34 and 36 are enabled by a signal from flip-
flop 26 on either line 52 or line 50, respectively. 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. Assume for
purposes of example only that 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 coupled to 60 Hz signal on line 99 as an input
to storage counter register 48 which begins to store the pulses
therein. When the next heartbeart occurs, transducer 24 produces
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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
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1 AND gate 74 which also has as the other input thereto the output
2 on line 76 of storage counter register 48. Thus, the input
3 to storage counter register 48 is removed and the output, the
4 contents thereof, is coupled on line 76 through AND gate 74 Oll
line 78 through OR gate 58 on line 60 to input register 52. Thus
6 the pulses that were stored in storage counter register 48 between
7 heartbeats is now stored in input register 62.
8 S multaneously, the output of flip-flop 26 on line 52
9 is coupled as an enabling signal to AND gate 34 which, of course,
10 ,has as its other input on line 30, the 60 Hz signal. Also, the
11 output of flip-flop 26 on line 52 is coupled to one-shot multi-
12 vibrator 68 which produces a spike on its output line 70 that
13 clears storage counter register 42. AND gate 34 therefore begins
14 to pass the 60 Hz pulses on line 40 to storage counter register
42 for storage therein. At the same time, since the sianal on
16 line 50 from ~-lip-flop 26 has been removed when the flip-flop
17 changed states, the enabling signal has been removed from AND
18 gate 54 and the contents of storage counter register 42 cannot be
19 removed or gated therefrom.
Also, the output of transducer 24 produced by the last
21 heartbeat is coupled via conductor 84 through OR gate 86 on line
22 82 as an enabling signal to input register 62. Thus, the pulses
23 stored in input register 62 from storage counter register 48 are
24 gated on line 78 into the arithmetic unit 80. Since the arith-
metic unit divides 3600 by the number of pulses stored between
26 heartbeats, it produces a signal on line 88 which is coupled
27 to display 90 representing the actual heartbeat rate.
28 When the next heartbeat occurs, flip-flop 26 is reset
29 ~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
31 line 30 into storage counter register 42. At the same time,
32 however, an enabling signal on line 50 from flip-flop 2h enahles

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1 AND gate 54 thus allowing the contents of storage register 42 to
2 be gated out on line 56 through AND gate 54, OR gate 58 and line
3 60 to input register 62. As described previously, however,
4 storage counter register 48 is now enabled and begins storing
the 60 Hz pulses.
6 Thus, it can be seen that with the appearance of a
7 heartbeat, one of the counters 42 and 48 begins to store pulses
8 from oscillator 28 until the next heartbeat is produced. At that
9 time, the 60 Hz input pulses from clock circuit 94 are trans-
ferrèd from the first counter to the second counter while the
11 output of the first counter is coupled to an input register 62
12 for storage purposes. Thus, the number of pulses occurring
13 between heartbeats is stored alternately in counters 42 and 48
14 and transferred alternately to input register 62.
As stated earlier, in order to properly gate the data
16 stored in input register 62 on line 78 to arithmetic unit 80, a
17 gating signal is required on line 82. This signal can be produced
18 in any well known means but is produced in the preferred manner
19 by coupling the output pulse from transducer 24 on line 84 to
OR gate 86, line 82 and input register 62. Thus, each time
21 a heartbeat is detected and transducer 24 produces an electrical
22 pulse on line 84, that pulse is used as a gating signal to gate
23 the information stored in input register 62 to arithmetic unit
24 80 via line 78.
The arithmetic unit 80 is programmed, as indicated
26 earlier, to divide 3600 by whatever count or number of pulses is
27 stored in input register 62. Thus, as shown in the table in
28 FIG~RE 5, if input register 62 is storing a count of 20, the
29 arithmetic unit 80 will produce an output on line 88 which
represents 180 heartbeats per minute and this output is coupled
31 to display 90 where it is displayed in numerical form. In like
32 manner, if 50 pulses are stored in input register 62, the

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arithmetic unit 80 will produce an output on line 88 representing
2 72 heartbeats per minute which will be displayed by display 90 in
3 numerical form.
4 Thus, there has been described and illustrated a novel
circuit which will not only monitor the heartbeat of the user
6 but which will produce a digital display of the heartbeat rate
7 at any instant. ~- ~
8 It may be important to establish a warning signal
9 if a predetermined upper limit of heartbeat rate is exceeded
or a predetermined lower limit of heartbeat rate is not reached.
11 This may be accomplished by storing in a first register a
12 predetermined number of oscillator pulses representing a desired
13 upper limit, for instance 30 pulses which would represent 120
14 heartbeats per minute and a predetermined number of pulses in a
15 ~second register representing a lower limit which may be, for
16 example, 60 pulses which would represent 60 heartbeats per minute.
17 By then comparing the contents of each register with the number
18 lof pulses stored in input register 62 representing the current
19 heartbeat rate, warning signals may be generated when the upper
20 limit is exceeded or the heartbeat rate does not reach the lower
21 limit. It is desirable to simply have physical contacts on the
22 monitor casing such as a button which can be depressed to
23 establish both the upper and lower limits. Such a circuit is
24 'shown in FIGVRE 3. Thus, the output of oscillator 28 on line 92
25 is coupled to a clock circuit 94. Clock circuit 94, as stated
26 earlier, has registers for developing signals representing
27 seconds, minutes and hours. Inasmuch as the oscillator 28 is
28 loperating at a frequency of 3600 hertz, a "heartbeat" register
29 in clock 94 could divide the input signal and store 60 pulses
30 per second. However, if 60 pulses per second were to be stored
31 in a register representing upper or lower limits, the user would

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1 not be able to accurately determine when the desired n~ber of
2 pulses has been stored because 60 pulses would occur in just one
3 second. For that reason,the output of the "heartbeat" register
4 on line 98 is coupled to a divider circuit 100 which divides the
number of pulses being received by any convenient number but, in
6 the preferred example, by three which would enable the output of
7 divider circuit 100 to be twent~ pulses per second on line 102.
8 Thus, the output of divider circuit 100 on line 102 may be coupled
9 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
11 Iregister 104 which stores pulses representing the predetermined
12 upper limit heartbeat rate desired. If switch 20 is actuated, the
13 pulses from divider circuit 100 on line 102 are coupled to
14 register 106 which stores pulses representing the predetermined
lower limit heartbeat rate desired. Switches 19 and 20 are so
16 arranged with switch 23 coupled to the input of counters 42 and 98
17 that whenever either switch 19 or 20 is actuated, switch 23 is
18 opened to remove the output of oscillator 28 to the counter
19 circuits. Separate switches could, of course, be used. The
reason that this is necessary is to be able to utilize the slower
21 occurring pulses (i.e., 20 pulses per second) from divider circuit
22 100 as the reference source in order to be able to visually
23 observe the display while physically depressing switch 19 or
24 switch 20 until the proper heartbeat rate is reached. Thus, if
25 Iswitch 19 is actuated, thereby coupling the output of divider
26 circuit 100 to register 104, it also opens switch 23 to prevent
27 the output from the "heartbeat" register from going to the
28~ counter circuits 42 or 48 and also couples the pulses from
29 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. Thus,
31 the same pulses that are being stored in register 104, the
32 register storing pulses representing the predetermined upper
33 limit of heartbeat rate, are being coupled to the arithmetic

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unit 80 for processing so that the display 90 will read directly
the heartbeat rate represented by the pulses being stored in
register 104. With 20 pulses per second appearing from divider
network 100 on line 102, when either switch 19 or switch 20 is
depressed, 20 pulses per second are being stored in the
corresponding register 104 or 106. This obviously causes a rapid
change at display 90. It would require three seconds to store
60 pulses representing 60 heartbeats per minute. If it is
desired to have a slower rate of storage of the pulses from the
divider network 100 into registers 104 or 106, of course divider
network 100 may divide by four, six or any other desired number
instead of three.
To set the lower predetermined limit of heartbeat
rate, switch 20 is depressed thus coupling the output from
divider circuit 100 on line 102 to register 106. Again, that
same output is coupled through OR gate 108, line 110, OR gate
58, line 60 and input register 62 to arithmetic unit 80. In
like manner, as long as switch 20 is held depressed, the user
may view the display until it reads the appropriate heartbeat
rate and then release switch 20.
As stated earlier, 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 caunting 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. For this purpose, switch 112 may couple
power source 114 to a multivibrator 116 that produces an
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- 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. However, muItivibrator 116 could be adjusted to any desired
frequency to provide a gating signal on line 82 for input
register 62.
Once the upper and lower heartbeat rate limits have
been established by storing pulses in registers 104 and 106,
and the monitor is in operation, 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. In
like manner, if the number of puIses stored in input register 62
is less than the number of pulses stored in register 106, then
comparator 124 produces an output signal on line 132 which also
passes through OR gate 128 to activate alarm 130. Thus, the
user may set a predetermined high heartbeat rate and low heart-
beat 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.
Inasmuch as 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
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i,
which continuously maintains time or the output of arithmetic
2 unit~ to display 90. Thus, while the pulse monitor is not
3 being used as a pulse monitor it may be utilized as a clock
4 or watch simply by placing switch 25 in the appropriate position.
5, FIGURE 4 illustrates the various waveforms that appcar
6!lat particular points in the circuit shown in FIGURE 3. Graph A
7 1l illustrates the electrical pulses produced by transducer 24 as
8 leach heartbeat is detected by sensor 22.~ Graph A shows, as an
9jlexample only, the electrical pulses getting closer together with
lO Itime indicating that the heartbeat rate is increasing. Graph B
11 jillustrates the 60 Hz pulses from clock circuit 94 which are
12~ibeing stored in one of the storage counter registers 42 or 48.
13 Assume, for purposes of example only, that they represent the
14 Ipulses being stored in counter 42. ~hen electrical pulse 136 is
15 1generated by the next heartbeat, flip-flop 26 changes states and
161! graph C shows that the pulses from oscillator 28 are now being
17'lstored in storage counter register 48. While those pulses are
18 1¦ being stored in register 48, the pulses in storage counter
l9llregister 42 are gated out and coupled to input register 62 as
20,¦shown in graph D. Assume that 50 pulses were stored in storage
21,counter register 42 during the interval between pulses 136 and
22 138 representing an interval between the heartbeats of the user.
23 Fifty pulses, as shown in FIGURE 5, represents 72 heartbeats
24l per minute, the average heartbeat of an individual. When
25 1l electrical pulse 140 occurs, flip-flop 26 again changes state
26 thus causing the 60 Hz pulses from clock circuit 94 to again
27!lbe stored in counter register 42 while those pulses previously
28 1l stored in counter 48 as shown in graph C are gated out again
29l!to the input register 62 as shown in graph D. This time, however,
30'lthere are only 48 pulses stored in input register 62. ~lthough
31lnot shown in the table in FIGURE 5, the heartbeat rate can be
32lcalculated from the formula previously given and shown to be
33l75 beats per minute. Thus, the heartbeat rate is increasing.
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'I When electrical pulse 142 occurs, again flip-flop 26 changes
2 states thus causing the 60 Hz pulses from clock circuit 94 to be
3 , stored in counter 48 and those pulses stored previously in counterj
4 1 42 are gated out to input storage register 62. As can be seen in '
! graph D of FIGURE 4, 40 pulses were stored in counter 42 during
6 I the previous interval. Again, from the table shown in FIGURE 5,
7 1l it can be seen that 40 pulses represent a heartbeat rate of 90
8 I beats per minute. When the next electrical pulse 144 occurs,
9 ll again, flip-flop 26 changes states thus causing the 60 Hz pulses
¦I from clock circuit 94 to be stored in counter 42 and ~he output
11 Ijof counter 48 transferred or gated to input register 62. From
12 'Igraph D of FIGURE 4 it will be seen that 30 pulses were stored
13 during the last cycle in counter 48. Again, from the table shown
14 l~in FIGURE 5 it can be seen that thirty pulses represent a
jlheartbeat rate of 120 beats per minute. Thus, display 90 is
16 I continuous and, shows, in the example given, the increase in
17 ,Iheartbeat rate as determined by the number of pulses being stored
18 1 in counter registers 42 and 48 and mathematically determined by
19 l¦arithmetic unit 80.
! 1.
,I Thus, the present invention has several advantages
21 'over the prior art devices. First, it gives a direct digital
22 1l read out of the heartbeat rate of the user at any instant.
23 ,jSecondly, predetermined high and low heartbeat rate limits may
24 ~ be set which, if the actual heartbeat rate exceeds or does not
¦reach, activates an alarm to warn the user. Thirdly, these
26 lupper and lower predetermined limits are easily set by the user
27 ~lsimply depressing an upper limit key or a lower limit key and
2 8 ¦¦then reading the display output until the proper predetermined
29 1 limit is reached and then releasing the button or key. Fourth,
Ithe unit can be economically used as a wris t watch inasmuch as
31 a clock circuit already exists within the unit.
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~1~9471)
While the invention has been described in connection
2 iwith a preferred embodiment, it is not intended to limit the
3~!scope of the invention to the particular form set forth, but,
4'.'on the contrary it is intended to cover such alternatives,
51,modifications, and equivalents as may be included within the
6l¦spirit and scope of the invention as defined by the appended
7 Iclaims.
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