JPS60135029A - Blood stream and pulse detection apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a blood flow/pulse sensor that detects blood flow/pulse by reflecting light from a light emitting part on a part of the human body and receiving the light at a light receiving part.

[Background technology]

FIG. 1 shows the sensing part of a conventional photoelectric reflection type pulse detection device d which detects the pulse by pressing a detection device composed of a light emitting element 2 and a light receiving element 3 against a living body 1. The operation is such that the light emitted from the light emitting element 1 is reflected by the living body 1 and the reflected light is detected by the light receiving element 3. According to the above-mentioned photoelectric reflection type pulse detection device, as shown in FIG. 2, the detected waveform becomes a detection waveform in which the 1st pulse due to body movement appears in addition to the pulse wave.

Therefore, due to body tremors during exercise or in cold environments,
There was a problem in that pulse detection errors often occurred.

[Purpose of the invention]

The present invention has been made to improve the above-mentioned problems, and its purpose is to provide a blood flow/pulse detection device that is free from detection errors due to body movements.

[Disclosure of the invention]

The present invention is characterized in that, in addition to the pulse wave signal that includes body movement, a body movement signal is detected and the difference is taken, thereby making it possible to obtain a pulse that is less affected by body movement. The present invention will be explained below based on the drawings shown as examples.

(Example 1) As shown in FIG. 3, in addition to the conventional light-emitting element 2 and light-receiving element 3, a light-receiving element 4 and a light-receiving element 4 are used to detect body movement. A cord 5 is provided, and body movement is detected using reflection from a reflector 6 placed in contact with the living body 1. The configuration of the detection circuit u4 is shown in FIG. 4, and the signal waveforms of each part are shown in FIG. Among the signals emitted from the light emitting circuit 7 and reflected by the living body 1, a pulse wave signal 3 including body movement
is detected by the detection circuit 8, and the body motion signal +f6, that is, the signal reflected by the reflection plate 6, is detected by the detection circuit 9. The differential circuit 10 takes the difference between the four detection signals &1b and obtains a pulse wave only signal C. Note that "1" is a filter circuit, and the branches are comparator circuits.

In this example, as shown in FIG.
Even if P-1 is used for both body movement detection and pulse detection including body movement, a pulse wave signal such as 14 can be obtained.

(Example 2) This example utilizes the spectral characteristics of a light emitting diode and the spectral characteristics of blood. FIG. 7 shows the spectral state of light, and FIG. 8 shows the spectral characteristics of the light emitting diode.

Figure 9 shows the optical characteristics of blood, 5QQr1m
Distinctive spectral characteristics can be obtained in the region from red light to infrared light. As shown in FIG. 10, the sensor section of this embodiment is constructed by bringing a light emitting element L3 constituted by a red or near-infrared light emitting diode and a light receiving element 3 constituted by a phototransistor or a solar cell into contact with a living body 1. Obtain pulse wave confidence including pulse wave. In addition, a green light emitting diode provides IV
A body movement signal is detected by the light emitting element 14 and the light receiving element 5, which are formed of four light emitting elements 14 and a light receiving element 5. This utilizes the optical properties of blood. That is, as shown in FIGS. 8 and 9, the area of light emitted from the green light emitting diode has zero transmittance in the blood, that is, the green light is completely absorbed by the blood, so the influence of the blood is small. It can only detect reflections caused by body movements.

Therefore, with these signals, a pulse wave signal that is not affected by body movement can be obtained. Note that 15 is a partition wall that prevents light emitted from each light emitting element from entering the other light receiving element. In this embodiment, as shown in FIG. 11, if an infrared light emitting diode 16 is used as the light emitting element I3 and an infrared cut filter is applied to the light receiving element 5, the accuracy will be further improved.

Next, a detection circuit for the second embodiment will be shown. FIG. 12 shows its configuration, and FIG. 13 shows signal waveforms of each part. The switching circuit 18 alternately causes the light emitting circuit 19 for pulse wave detection including body movement and the light emitting circuit 19 for detecting body movement to emit light by switching. The above-mentioned double-light optical circuit 19. Detection circuits 21 and 22 respectively detect the reflected light from the incident light. The output waveforms "Ilb+" of the detection circuits 21 and 22 are connected to the light emitting circuit 19 by the switching circuits 24 and 24, respectively.
, 211, by switching in synchronization with a
The waveform becomes 2 + b2.

The above waveform is further rectified by a rectifier circuit 26, and its output a3 + b3 is compared by a differential circuit 27, and the difference between the two output waveforms 3+b3 appears as an output waveform. is a comparator circuit.

” The output waveform a1+bl of the detection circuit 21 and η is,
A pulse wave signal including body movement and a body movement signal are alternately displayed in a waveform by switching. This is because part of the signal from the light emitting circuit I also enters the detection circuit 21, or the signal from the light emitting circuit I
This is because a part of the signal from 9 also enters the detection circuit ρ.

The above waveform J+'s is connected to the switching circuit O, 24,
By synchronizing the light emitting circuit +9 and +, if the waveforms of only the signals from the light emitting circuit 19 take a2 difference, the signal waveform of the difference becomes a pulse waveform that is not affected by body movement.

〔Effect of the invention〕

” According to the present invention, the pulse wave 14 including body movement
By capturing the signal and body movement signal separately and taking the difference between them, it is possible to obtain a pulse wave signal that does not include body movement, making it possible to detect pulse waves during exercise and in cold conditions. A pulse blood flow detection device that can be easily and accurately detected has been provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the sensor section of a conventional pulse rate detection device, FIG. 2 is a pulse wave signal waveform including body movement obtained by the conventional pulse rate detection device, and FIGS. FIG. 4 is a configuration diagram of a detection circuit according to the first embodiment, and FIG. 5 is a signal waveform of each part in the detection circuit of FIG. 4. @Figure 7 is a spectral state diagram of light, Figure 8 is a spectral characteristic diagram of a light emitting diode, Figure 9 is an optical characteristic diagram of blood, and Figures 10 and 11 are pulse rates showing the second embodiment of the present invention. , FIG. 12 is a configuration diagram of a detection circuit according to a second embodiment of the present invention, and FIG. 13 shows signal waveforms of various parts in the detection circuit of FIG. 12. DESCRIPTION OF SYMBOLS 1... Living body, 2.4... Light emitting element, 3.5... Light receiving element, 6... Reflection plate, 10, 27... Differential circuit, 13... Red or near infrared Light emitting diode, 14...
・Green light emitting diode, m, z3.24...Switching circuit. Patent applicant Matsushita Electric Works Co., Ltd. Attorney Toshimaru Takemoto (and 2 others) Figure 7 Figure 8 Shincho (hm) Figure 9 Shincho (nm) Figure 10

Claims (3)

[Claims] (1) Applying light emitted from a light emitting element to biological tissue,
By detecting the deterioration of the reflected light with a light receiving element, a blood flow/pulse detection device that measures blood flow/pulse detects a pulse wave signal including body movement and a body movement signal, and then detects the difference between the two signals. A blood flow/pulse detection device that is characterized by being able to obtain accurate pulses by measuring blood pressure. (2) The blood flow and blood flow according to claim 1, characterized in that the body movement detection is performed by a repellent plate that is in contact with a living body and a light receiving element that receives the reflected light reflected by the repellent plate. Pulse detection device. (3) The body 111JI detection is performed by a light emitting element having a luminescent color in a band different from the spectral characteristics of blood, and a light receiving element that receives reflected light with respect to the incident light from the light emitting element. The blood flow/pulse detection device according to item 1.