JPH034207B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects respiration rate, heart rate, or both in a non-contact manner based on body surface displacement without attaching electrodes or the like to the subject. The present invention relates to a non-contact body surface displacement detection device.

[Problems to be solved by conventional technology and invention]

In clinical practice, it is important to monitor respiratory rate or heart rate over a long period of time during surgery or with a device such as a CCU. In addition, constant monitoring of the respiratory and circulatory systems of premature infants is important, and screening for sudden death syndrome, which has recently become the largest cause of perinatal death, is important.

A typical measurement method for this purpose is a contact method in which an electrode or transducer is attached to the subject and a lead wire is led out. In this case, the lead wires may interfere with nursing care.
Moreover, the burden on the examinee is large.

Therefore, recently, as a non-contact measurement method,
It is well known to irradiate the body surface with ultrasonic waves and detect respiratory waves or heartbeat waves as body surface displacement from the phase change of the reflected signal detected by a microphone.
However, this method has the problem that high-precision measurement is difficult due to noise caused by air fluctuations and interference of reflected waves caused by non-uniform movement of the body surface. In addition, a method of irradiating microwaves is well known, but similarly, errors occur due to interference of reflected waves due to non-uniform movement, and installation becomes complicated.

Therefore, it is an object of the present invention to provide a body surface displacement detection device that measures respiration rate or pulsation rate with high precision using a simple, non-contact configuration.

[Means for solving problems]

In order to achieve this objective, the present invention detects the position of a light source 2 that irradiates a light beam onto the body surface 1 of a subject, and a light spot where the reflected scattered light is incident through a condenser lens 4. Optical spot position sensor 10 and body surface displacement wave detection circuits 14 and 17 that detect body surface displacement waves from the detection signal of this sensor.
and body surface displacement number counting circuits 20 and 25 that count the body surface displacement waves for a predetermined period of time. Note that the symbols in parentheses refer to those in the embodiment described later.

[Effect]

Scattered light of the light beam reflected by the body surface 1 of the abdomen, chest, or back of the subject is condensed and enters the light spot position detection sensor 10 as a light spot. The incident position of this light spot is displaced as the reflection position of the light beam changes according to body surface displacement due to respiration or heartbeat, and therefore the light spot position detection sensor 10 detects the position corresponding to the displacement. Output a signal. Body surface displacement wave detection circuit 1
4 and 17 detect a desired body surface displacement wave that does not include noise from this detection signal, and output the output signal for a predetermined time to body surface displacement number counting circuits 20 and 25.
count.

[Embodiments of the invention]

1 to 3 show an embodiment of the present invention. In FIG.
A light beam of approximately 1 mW is irradiated from a laser light source 2 located at a remote location through a focus lens 3 with a focal length of, for example, 5 cm. The reflected and scattered light is condensed into a spot through the condenser lens 4, and is incident on the optical spot position sensor 10. This sensor consists of a well-known semiconductor position sensing device (PSD) 11 having two electrodes each outputting a photocurrent depending on the displacement from the center position, and an I/O device that converts each photocurrent into a voltage signal. It is comprised of a /V conversion circuit 12 and a correction circuit 13 that converts the voltage signals of both electrodes into a voltage signal whose voltage level changes in accordance with the incident position of the light spot. These optical systems 2 to 4, 11 are mounted, for example, on a stand, and irradiate light through a transparent case to a premature baby in the incubator or directly to an adult baby.

Reference numeral 14 denotes a respiratory wave detection circuit, which includes a bandpass filter 15 with a pass band of 0.08 to 2 Hz to remove noise included in the output signal of the correction circuit 13, and detects respiratory waves from the signal input through this filter. The main body 16 is a respiratory wave detection circuit. This circuit body is constituted by, for example, the circuit shown in FIG. 2, which is well known per se. 17 is a heartbeat wave detection circuit, which also has a passband of 10 to 20Hz in order to remove noise included in the output signal of the correction circuit 13.
It is composed of a bandpass filter 18 and a waveform shaping circuit 19 that pulses its output signal.

20 is a respiration rate counting circuit for counting the respiration rate for a predetermined period of time, which includes a counter 21 for counting the output signal of the respiratory wave detection circuit main body 16, a data holding circuit 22 for holding the counted value, and a respiration rate counting circuit for counting the respiration rate for a predetermined period of time. It consists of a clock generating circuit 23 which generates a clock to reset the counter 21 and latch the data holding circuit 22. A heart rate counting circuit 25 counts the heart rate for a predetermined period of time, and is composed of a counter 26 and a data holding circuit 27 that holds the counted value, and shares the clock generation circuit 23.

28 is a display section that displays the respiration rate and heart rate data held in the data holding circuits 22 and 27; 29;
is the recording section that performs the recording.

The operation of the respiration rate detection device configured as described above is as follows.

The chest 1 is continuously irradiated with a well-converged light beam from a laser light source 2 through a focus lens 3. The incident light beam is scattered by the chest 1, and the reflected and scattered light is converged by the condenser lens 4.
It enters PSD11. As a result, the incident position of the light spot changes in response to the displacement of the chest wall due to respiration and heartbeat. Therefore, the correction circuit 13 outputs a signal whose voltage level changes depending on the displacement of the chest wall.

The output signal of the correction circuit 13 inputted to the respiratory wave detection circuit 14 has heartbeat components etc. reduced in a bandpass filter 15, and is supplied as an input signal V1 to the respiratory wave detection circuit main body 16 shown in FIG.

In the same figure, A1 and A2 are operational amplifiers, A3
is a comparator, and A4 is an inverter. Analog switch SW1 and diode D that are turned on when output signal V5 of comparator A3 is “1”
1 and capacitor C1 constitute a peak hold circuit, and analog switch SW2, which is turned on when output signal V5 is "0", diode D2 and capacitor C1 constitute a bottom hold circuit. The operation is well known, but to explain period A, it is assumed that just before that period, as shown in FIG. 3, the output signal V5 of comparator A3 had become "1" and peak detection was being performed. Inverted signal V2 obtained by inverting input signal V1 by operational amplifier A1
is divided by resistors R3 and R4, and the operational amplifier A2
and its peak value is input to comparator A3 -
This becomes the input signal V4. Since the +input signal V3 of the comparator A3 is inputted after the inverted signal V2 and the output signal V5 are divided by the resistors R6 and R7, the comparator A3 is inverted due to the fall of the inverted signal V2, and the output signal V5 is "0". "become. As a result, the analog switch SW2 is turned on and bottom detection is performed. +input signal V3 of comparator A3
In this case, the inverted signal V2 and the output signal V5 are connected to the resistor R6,
The voltage is divided at R7 and is at the bottom level - below the input signal. When the inverted signal V2 rises, the comparator A3 is inverted and the output signal V5 becomes "1" again.
become. As a result, comparator A3 outputs output signal V5, which is a logic signal corresponding to the respiratory wave cycle.
is output.

Similarly, the output signal of the correction circuit 13 is also input to the heartbeat wave detection circuit 17, and a bandpass filter 18 removes noise such as respiratory wave components to detect only the heartbeat wave. converted into corresponding pulses.

The clock generation circuit 23 generates a clock every minute, causes the counters 21 and 26 to count the respiratory wave signal and heartbeat wave signal during that time, and the data holding circuit 2
2, 27 to hold breathing rate and heart rate data that are updated every minute. The display section 28 numerically displays the breathing rate and heart rate, and the recording section 29 continuously records them on recording paper.

In addition, in the above-mentioned embodiment, the circuit portions 14 to 1
By eliminating circuit portions 6, 21 to 22 or circuit portions 17, 25, it is also possible to configure only a heart rate detection device or a respiration rate detection device. As the optical spot displacement sensor 10, an image sensor such as a CCD type may be used, and the displacement of the optical spot position on the imaging surface may be detected by reading and scanning the imaging surface. LED as the light source of the light beam
It is also possible to use

〔Effect of the invention〕

As described above, by detecting the displacement of the reflected light spot in response to body surface displacement according to the present invention, all the advantages of the non-contact type can be maintained, and since it is an optical type, the spot diameter can be easily reduced. , therefore, measurement accuracy is improved since there is less interference compared to ultrasonic waves and microwaves. Similarly, since the spot diameter can be made small, even if the person is wearing clothes and the surface shape is irregular, interference is unlikely to occur, so body surface displacement can be reliably detected even through the clothes. Furthermore, since light is used, the problem of interference with peripheral devices is eliminated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the optical system and attached circuit of a non-contact body surface displacement detection device according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating the circuit configuration of the respiratory wave detection circuit main body of the same embodiment. The figure and FIG. 3 are diagrams showing the voltage relationship of each part in FIG. 2.

Claims (1)

[Claims] 1. A light source that irradiates a light beam onto the body surface of the subject, a light spot position sensor that detects the position of the light spot formed by passing the reflected scattered light through a condensing lens, and a detection signal from this sensor that detects the position of the body surface. A non-contact body surface displacement detection device comprising: a body surface displacement wave detection circuit that detects a displacement wave; and a body surface displacement number counting circuit that counts output signals of the body surface displacement wave detection circuit for a predetermined period of time.