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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic sphygmomanometer designed so
that measured data which is stored in the memory can be transmitted to an
external data processor by means of light communication.
2. Description of the Related Art
There has recently been proposed an electronic sphygmomanometer for finger
which is provided with a pulse wave detecting photoelectric sensor
designed to detect a pulse wave by a combination of light-emitting and
-receiving elements.
FIG. 3 is a block diagram showing the pneumatic system and circuit
configuration of the recently proposed electronic sphygmomanometer for
finger.
A finger cuff 1 is defined by a cylindrical rubber bag formed such that a
finger can be inserted thereinto. The finger cuff 1 has a pulse wave
detecting photoelectric sensor 2 comprising a light-emitting element
(light-emitting diode) 21 and a light-receiving element (phototransistor)
22 which are disposed on the inner peripheral surface of the cylindrical
cuff 11. The finger cuff 11 is connected to a pressurizing motor 12
through a pneumatic tube 11. A slow exhaust valve 13, a rapid exhaust
valve 14 and semi-conductor pressure sensor 15 are disposed at appropriate
positions, respectively, along the pneumatic tube 11. The pressurizing
motor 12 is connected to a motor driving circuit 31 which is, in turn,
electrically connected to an MPU (microprocessor unit) 3 (described
later), while the rapid exhaust valve 14 is connected to a rapid exhaust
valve driving circuit 32, whereby the pneumatic system is driven and
controlled. The semiconductor pressure sensor 15 detects the level of
pressure inside the cuff 1 and outputs an analog quantity through an
amplifier circuit 33. The analog quantity is converted into a digital
quantity through an A/D converter 34 and this digital quantity is output
to the MPU 3. It should be noted that another light-receiving element 16
for sensing a finger insertion condition is disposed at an appropriate
position on the inner peripheral surface of the cuff 1.
The light-emitting element 21 of the cuff 1 projects light on the finger in
response to an output command from the MPU 3, and the light-receiving
element 22 detects the quantity of reflected light from the finger (i.e.,
the quantity of reflected light which varies in accordance with the change
in volume of the artery). The quantity of reflected light is passed
through a buffer amplifier 35 and the DC portion thereof is output to the
MPU 3 through the A/D converter 34. The quantity of reflected light is
also delivered to a filter 36 through the buffer amplifier 35. In the
filter 36, the noise component (DC component) is removed and only a change
in the pulse wave is taken out and amplified in an amplifier circuit 37.
The amplified analog quantity is converted into a digital value in the A/D
converter 34 and this digital value is output to the MPU 3.
The MPU 3 has a function of allowing the light-emitting element 21 to emit
with an intensity appropriate to a subject of measurement through a D/A
converter 38 and an LED driving circuit 39 and determining a highest blood
pressure value and a lowest blood pressure value using a predetermined
algorithm on the basis of the pulse wave amplitude of the pulse wave
signal taken in from the light-receiving element 22 and the cuff pressure.
The MPU 3 also has a function of storing the results of measurement (i.e.,
the determined blood pressure values) in a memory incorporated therein and
digitally displaying the measured values on a display (LCD) 43.
To the MPU 3 are further electrically connected a power supply circuit 41
provided with a power supply switch 40 and a measurement start switch 42.
One type of the above-described electronic sphygmomanometer for finger is
designed so that blood pressure values measured on a plurality of
occasions, that is, past data, can be stored in the memory of the MPU for
a predetermined period of time (e.g., one month). This measured data
storage type electronic sphygmomanometer is considerably effective in
diagnostically examining a change in the patient's condition since it is
possible for an expert such as a doctor to make a diagnosis on the basis
of a plurality of measured data (blood pressure values) obtained for a
predetermined period of time which are transmittted from the electronic
sphygmomanometer to an external special-purpose data processor (installed
in a hospital or the like).
However, in order to transmit measured data obtained on a plurality of
occasions and stored in the MPU (memory) from the conventional electronic
sphygmomanometer to an external special-purpose data processor with a
display unit which is installed in a hospital or the like, it is necessary
to attach an interface to the MPU, connect together the instrument body
and the special-purpose data processor through a connecting cable, and
transmit measured data through this transmission line. Accordingly, there
is a need for extra hardware arrrangements such as an interface, output
buffer, connector, etc. for transmitting the measured data stored in the
memory. Thus, the prior art suffers from the disadvantages that the
overall size of the electronic sphygmomanometer increases and the cost of
the instrument rises.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, it is a primary object of the
present invention to provide an electronic sphygmomanometer which is
designed so that measured data stored in the memory can be transmitted to
an external data processor readily and inexpensively without the need for
a special hardware arrangement.
To this end, the present invention provides an electronic sphygmomanometer
having a cuff, a pulse wave detecting photoelectric sensor including a
light-emitting element and a light-receiving element which are disposed on
the cuff, and memory means for storing measured data, wherein the
improvement comprises: mode selecting means for selecting either a
measuring mode or a transmitting mode; and means for allowing the
light-emitting and -receiving elements of the pulse wave detecting
photoelectric sensor to be used as light-emitting and -receiving elements
for transmission of measured data in the transmitting mode.
By virtue of the above-described arrangement, in the measuring mode,
measurement of blood pressure is executed and measured blood pressure
values are displayed on a display (LCD). In addition, the measured data
(blood pressure values) are stored in the memory of the MPU. When pieces
of measured data which were obtained on a plurality of occasions are to be
transmitted to an external data processor installed, for example, in a
hospital so that a doctor makes a diagnosis on the basis of the measured
data, transmission means which is connected to the external data processor
is fitted into the cuff of the sphygmomanometer. In this state, the
light-emitting and -receiving elements of the transmission means face the
pulse wave detecting photoelectric sensor (i.e., the light-receiving and
-transmitting elements for the measuring mode) provided in the cuff. If,
in this state, a transmitting mode switch which is provided on the
instrument body is turned ON, the photoelectric element (light-emitting
element) for measurement is allowed to be used as an optical element for
tranmission of measured data. In other words, the blood pressure measuring
mode is changed to the measured data transmitting mode. Then, the MPU
reads measured data stored in the memory and outputs digital signals
representing the measured data to the optical element (light-emitting
element) for transmission to thereby flash the light-emitting element.
This light (flashing signal) is received by the light-receiving element of
the transmission means connected to the external data processor and the
measured data is thereby transmitted to the circuit section of the
external data processor.
It should be noted that the measuring mode may be automatically changed to
the transmitting mode by the operation of the MPU. More specifically, the
arrangement may be such that the external data processor causes the
light-emitting element of the transmission means to emit light and this
light is received by the light-receiving element provided on the cuff to
request the MPU to change over the operating mode from the measuring mode
to the transmitting mode. In this case, the transmitting mode switch is
unneccesary.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and advantages of the present
invention will become more apparent from the following description of the
preferred embodiment thereof, taken in conjunction with the accompanying
drawings, in which like reference numerals denote like members, and of
which:
FIG. 1 is a block diagram showing the pneumatic system and circuit
configuration of one embodiment of the electronic sphygmomanometer
according to the present invention;
FIG. 2 is a sectional view showing the cuff having transmission means
fitted thereinto; and
FIG. 3 is a block diagram showing the pneumatic system and circuit
configuration of a conventional electronic sphygmomanometer.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be described hereinunder in more detail with
reference to FIGS. 1 and 2.
FIG. 1 is a block diagram showing the pnuematic system and circuit
configuration of one embodiment of the electronic sphygmomanometer
according to the present invention.
The electronic sphygmomanometer comprises an instrument body having an
electronic circuit section and a finger cuff 1 which is connected to a
pressurizing motor 12 provided on the instrument body through a pneumatic
tube 11 and which has a pulse wave detecting photoelectric sensor 2. An
external data processor 7 is provided with transmission means 6 which is
detachably fitted into the finger cuff 1. The transmission means 6 has
light-emitting and -receiving elements 61 and 62 for transmission which
correspond to the light-emitting and -receiving elements 21 and 22,
respectively, provided on the cuff 1 to transmit measured data to the
circuit section of the external data processor 7 by means of light
communication.
The finger cuff 1 is defined by a cylindrical rubber bag formed such that a
finger can be inserted thereinto. The finger cuff 1 has a pulse wave
detecting photoelectric sensor 2 comprising a light-emitting element
(light-emitting diode) 21 and a light-receiving element (phototransistor)
22 which are disposed on the inner peripheral surface of the cylindrical
cuff 11. The finger cuff 11 is connected to a pressurizing motor 12
through a pneumatic tube 11. A slow exhaust valve 13, a rapid exhaust
valve 14 and a semi-conductor pressure sensor 15 are disposed at
appropriate positions, respectively, along the pneumatic tube 11. The
pressurizing motor 12 is connected to a motor driving circuit 31 which is,
in turn, electrically connected to an MPU (microprocessor unit) 3
(described later), while the rapid exhaust valve 14 is connected to a
rapid exhaust valve driving circuit 32, whereby the pneumatic system is
driven and controlled. The semiconductor pressure sensor 15 detects the
level of pressure inside the cuff 1 and outputs an analog quantity through
an amplifier circuit 33. The analog quantity is converted into a digital
quantity through an A/D converter 34 and this digital quantity is output
to the MPU 3. It should be noted that another light-receiving element 16
for sensing a finger insertion condition is disposed at an appropriate
position on the inner peripheral surface of the cuff 1.
The light-emitting element 21 of the cuff 1 projects light on the finger in
response to an output command from the MPU 3, and the light-receiving
element 22 detects the quantity of reflected light from the finger (i.e.,
the quantity of reflected light which varies in accordance with the change
in volume of the artery). The quantity of reflected light is passed
through a buffer amplifier 35 and the DC portion thereof is output to the
MPU 3 through the A/D converter 34. The quantity of reflected light is
also delivered to a filter 36 through the buffer amplifier 35. In the
filter 36, the noise component (DC component) is removed and only a change
in the pulse wave is taken out and amplified in an amplifier circuit 37.
The amplified analog quantity is converted into a digital value in the A/D
converter 34 and this digital value is output to the MPU 3.
The MPU 3 has a function of extracting a pulse wave amplitude from the
pulse wave signal input thereto and determining a highest blood pressure
value and a lowest blood pressure value using a predetermined algorithm on
the basis of the pulse wave amplitude and the cuff pressure and also has a
function of storing the determined blood pressure values as measured data
in a RAM (memory) incorporated therein. Further, the MPU 3 has a function
of adjusting the reflectivity which depends on each individual subject's
finger. More specifically, the MPU 3 reads the reflectivity (refraction
level) of the subject from the DC component (the DC level carrying the
pulse wave) which is taken in directly from the buffer amplifier 35 and
controls the D/A converter 38 and the LED driving circuit 39 such that the
light-emitting element 21 emits light with a controlled intensity.
To the MPU 3 are further electrically connected a power supply circuit 41
provided with a power supply switch 40 and a measurement start switch 42,
together with an LCD (Liquid Crystal Display) 43 for displaying results of
measurement (blood pressure values) and a buzzer 44 for urging the
operator to perform various operations.
The feature of the present invention resides in that the MPU 3 is provided
with a function of selecting either a measuring mode or a transmitting
mode and the measured data stored in the memory is transmitted from the
light-emitting and -receiving elements 21 and 22 to the transmission means
6 of the external data processor 7 by means of light communication in the
transmitting mode.
In this embodiment, the mode selecting function of the MPU 3 is exemplarily
realized as follows. A measuring mode switch 51 and transmitting mode
switch 52 are connected to the MPU 3, and when the transmitting mode
switch 52 is turned ON, the measuring mode is changed to the transmitting
mode and the measuring element for detection of a pulse wave, that is, the
light-emitting element 21, is switched to an optical element 21 for
transmission of measured data (i.e., the light-emitting element 21 for
measurement is used as the light-emitting element 21 for transmission). On
the other hand, the transmission means 6 is a columnar member which is
fitted into the cylindrical cuff 1. The transmission means 6 has a
light-emitting element (light-emitting diode) 61 for transmission and a
light-receiving element (phototransistor) 62 for transmission which are
disposed at appropriate positions, respectively, on the peripheral surface
thereof so that, when the transmission means 6 is fitted into the cuff 1,
the light-emitting and -receiving elements 61 and 62 for transmission face
the light-receiving and -emitting elements 22 and 21, respectively, of the
cuff 1 (see FIG. 2). The transmission means (light-emitting and -receiving
elements 61 and 62) 6 is connected to the circuit section of the external
data processor 7 through a cable 71. Transmission of measured data from
the MPU 3 to the optical element (light-emitting element) 21 for
transmission of the cuff 1 is executed by substitutionally using the
control circuit for controlling the intensity of the light emitted from
the light-emitting element 21, that is, the combination of the D/A
converter 38 and the LED driving circuit 39. For example, the measured
data stored in the memory of the MPU 3 is output in the form of digital
signals to the D/A converter 38, and the LED driving circuit 39 drives the
light-emitting element 21 with a level corresponding to the logic state of
each of the bits constituting a code corresponding to each of the digital
signals. More specifically, the light-emitting element 21 is flashed in
accordance with codes corresponding to the measured data (signals). Thus,
the light-emitting element 21 outputs optical code signals.
In the electronic sphygmomanometer having the above-described arrangement,
when measurement of blood pressure is to be effected, the measuring mode
switch 51 is turned ON to select the measuring mode. When measured data
(blood pressure values) obtained in the past and stored in the memory is
to be transmitted to the external data processor 7, the transmission means
(columnar member) 6 is fitted into the cuff 1. In this state, the
light-emitting and -receiving elements 61 and 62 of the transmission means
6 face the light-receiving and -emitting elements 22 and 21, respectively,
of the cuff 1 (see FIG. 2). Then, the transmitting mode switch 52 is
pressed. In consequence, the light-emitting element 21 which is used to
detect a pulse wave in the measuring mode is substituted for an optical
element for transmission of measured data. In other words, the measuring
mode is changed to the transmitting mode. Then, the MPU 3 reads the
measured data stored in the memory and outputs the data signal to the D/A
converter 38 which, in turn, outputs an analog signal to the LED driving
circuit 39. Thus, the light-emitting element 21 is flashed to transmit the
measured data signal in the form of an optical signal. The light-receiving
element 62 for transmission receives the signal and transmits it to the
external data processor 7.
It should be noted that, although in the embodiment the measuring mode
switch 51 and the transmitting mode switch 52 are provided in order to
change the measuring mode to the transmitting mode, the measuring mode
switch 51 may be omitted, that is, the arrangement may be such that the
normal state of the instrument is defined as the measuring mode and the
measuring mode is changed to the transmitting mode by actuating the
transmitting mode switch 52.
Although in the embodiment the measurng mode switch 51 and the transmitting
mode switch 52 are provided on the electronic sphygmomanometer, the mode
selecting arrangement is not necessarily limited thereto. For example, the
arrangement may be such that a transmission request signal is sent to the
MPU 3 from the external data processor 7 through the light-emitting
element 61 for transmission and the light-receiving element 22 and the MPU
3 automatically changes over the operating mode from the measuring mode to
the transmitting mode in response to the request signal. In this case, it
is unnecessary to provide not only the measuring mode switch 51 but also
the transmitting mode switch 52.
Thus, according to the present invention, the pulse wave detecting
photoelectric element is allowed to be used as an optical element for
transmission and reception of measured data by changing over the operating
mode from the measuring mode to the transmitting mode. Therefore, if the
transmission means having light-emitting and -receiving elements for
transmission is fitted into the cuff, measured data can be transmitted
from the optical element for transmission to an external data processor
through the light-receiving element for transmission by means of light
communication. Thus, it is possible to transmit measured data to an
external data processor readily and inexpensively.
Accordingly, it becomes unnecessary to provide hardware arrangements such
as an interface, output buffer, connector, etc. for transmitting measured
data to an external data processor (special-purpose processor) as in the
case of the conventional electronic sphygmomanometer. Therefore, no extra
parts such as a connector or other attachments are exposed to the outside
of the instrument body. Thus, it is possible to obtain excellent product
design and further reduce the size and weight of the instrument.
Although the present invention has been described through specific terms,
it should be noted here that the described embodiment is not necessarily
exclusive and various changes and modifications may be imparted thereto
without departing from the scope of the invention which is limited solely
by the appended claim.
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