JPS62286435A - Brain wave detector - 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 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a pulse wave detector used as an industrial or general household medical device.

BACKGROUND OF THE INVENTION Conventionally, a pulse wave meter has been known as a medical device for observing the state of blood circulation in the human body. Among these, the photoelectric volume type fingertip plethysmometer, which can measure peripheral blood flow non-invasively, is highly praised for its practicality. This fingertip plethysmometer irradiates the fingertip with light containing wavelengths of 5,000 to 8,000 people, for which hemoglobin has selectively strong light absorption. The amount of hemoglobin is detected by reading the amount of light absorbed at this wavelength, and the pulse wave is detected from the amount of change in hemoglobin.

Problems to be Solved by the Invention However, with this configuration, the signal obtained from the light receiving element 3 includes an AC component indicating the amount of change in hemoglobin and a hemoglobin at the measurement site on the fingertip, as shown in FIG. A DC component indicating the amount of tissue to be removed is mixed. Also, this D
The C component is sufficiently larger than the AC component. Therefore, it is necessary to cut off the DC component at a certain DC level and detect only the AC component necessary for measurement.

However, the fingertip has countless blood vessels and tissues, and their composition and amount vary widely depending on the measurement site.

Therefore, maintaining reproducibility of the measurement site has become an important issue. Furthermore, there are cases in which measurements cannot be made for some people, and the cut level of the DC component must be readjusted each time this occurs.

The present invention solves these conventional problems and provides a pulse wave detector that is easy to use and highly reliable.

Means to Solve the Problem Summary In order to solve the problem, the pulse wave detector of the present invention includes a light emitting element that is turned on by a power source, a variable load resistor that changes the amount of light of this light emitting element, and a variable load resistor that changes the amount of light of this light emitting element. The light emitted from the element is irradiated onto the living body, the light receiving element receives the reflected light from the living body or the transmitted light that has passed through the living body, and the pulse wave signal obtained from this light receiving element is compared with a certain level. It has a comparator and a signal changeover switch, and is configured to change the value of the variable load resistor based on the signal output from the comparator.

Operation With the above configuration, the amount of light from the light emitting element is changed so that the level of the pulse wave signal received by the light receiving element is within a certain range. Therefore, the cut level of the DC component can always be measured at a constant level, and the measurement range can be expanded.

Embodiment Hereinafter, one embodiment of the pulse wave detector of the present invention will be described based on the drawings.

In FIG. 1, 1 is a light emitting element that is lit by a power source;
2 is a variable load resistor that changes the amount of light from this light emitting element 1;
3 is a light-receiving element that receives light reflected from the living body or transmitted light that has passed through the living body by irradiating the light emitted from the light-emitting element 1 onto the living body; 4 is a pulse wave obtained from this light-receiving element 3; This is a comparator that compares the signal 3a with a certain constant level 4a, ab. 5 is a load resistor, 6 is a changeover switch, and 7 is an amplification amplifier.

In the above configuration, when a finger is inserted between the light emitting element 1 and the light receiving element 2, the light emitted from the light emitting element 1 passes through the tip of the finger and is received by the light receiving element 2. If a light receiving element 2, such as Cds, whose resistance value changes in response to a change in the amount of light received, is used as the light receiving element 2, the amount of light transmitted through the fingertip can be converted into an electrical signal. When a tungsten lamp is used as the light emitting element 1, a significant change in hemoglobin in the blood vessels at the measurement site on the fingertip can be seen. As a result, the amount of change in blood within the blood vessel of the fingertip can be detected by the light receiving element 2 and detected as an electrical signal.

However, since there are tissues in the human body and measurement site in addition to hemoglobin, when light passes through, a certain constant value (hereinafter referred to as DC component) and the amount of change in hemoglobin (hereinafter referred to as AC component) are generated as electrical signals. Detected as . And this A
While the C component is several mV, the absolute value of the DC component is several volts, which is sufficiently large. Therefore, in order to amplify only the AC component, the DC component must be cut.

Capacitor coupling is a method for cutting DC components, but the frequency of AC components is approximately 1Hz to several 10Hz.
z and low frequency, and the signal level is only about a few tenths of the DC component, so it is extremely difficult to faithfully detect only the AC component. 9 There is a method that cuts the DC component. However, the tissue structure of the measuring section varies greatly depending on the subject, and the DC
There are a wide variety of components, and the reference voltage value must be reset each time. Therefore, as shown in FIGS. 1 and 2, first, the selector switch 6 is set to the comparator 4 side, and the pulse wave signal 3a detected and amplified by the amplification amplifier 6 has a certain level 4.a. . By this method, the value of the DC component of the pulse wave signal 3a detected from the light receiving element 3 is adjusted so as to always be constant.

Thereafter, the selector switch 6 is switched to the output side. the result,
Even if the tissue structure of the measurement site differs depending on the subject, there is no need to reset the reference value.

There is still a variable load resistor 2 that changes the amount of light from the light emitting element 1, but also changes the level of light received by the light receiving element 3. However, due to the characteristics of the pulse wave signal, it is highly sensitive.

Effects of the Invention As is clear from the above, the pulse wave detector of the present invention is configured to change the amount of light from the light emitting element in accordance with the pulse wave signal level of the subject. This eliminates the need for manual level adjustment, and enables easy and reliable measurement. The measurement results are still highly reliable and highly useful.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram showing one embodiment of the pulse wave detector of the present invention, FIG. 2 is a waveform diagram of one embodiment of the pulse wave detector of the present invention,
FIG. 3 is a waveform diagram of a conventional pulse wave detector. 1... Light emitting element, 2... Variable load resistance, 3-...
... Light receiving element, 4...-Comparator, 6...- Selector switch. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A light-emitting element that is turned on by a power source, a variable load resistor that changes the amount of light from this light-emitting element, and a living body is irradiated with the light emitted from this light-emitting element, and the light that is reflected by the living body or the transmitted light that has passed through the living body is collected. It has a light-receiving element that receives the pulse wave signal, a comparator that compares the pulse wave signal obtained from the light-receiving element with a certain fixed level, and a signal changeover switch. A pulse wave detector that changes the value.