JPS5829449A - Sensor for detecting pulse number in pulse meter - 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 The present invention relates to a pulse rate detection sensor for a pulse needle.

Conventionally, optical pulse detection methods including a light emitting source and a light receiving element have been known. This detects changes in light absorption due to the pulsation of blood vessels.The light absorption is only affected by light absorption in a relatively long wavelength range, so it is necessary to use a light source as a light source to detect pulses stably and accurately. It had the disadvantage of requiring special products and being expensive.

Furthermore, from the viewpoint of health management, it has been proposed to incorporate a pulse meter into a portable electronic watch, especially an electronic wristwatch, so that the pulse rate can be easily measured at any time and any place. However, providing a separate light source for the pulse meter increases the number of parts, increases the size of the wristwatch, and complicates assembly.

The present invention allows the use of a light emitting source with relatively wide band characteristics, making it inexpensive, and when incorporated into a wristwatch, it can also be used as an illumination lamp for a liquid crystal display device for time display. This reduces the number of parts and facilitates assembly.

Hereinafter, an application to an electronic watch with a pulse meter will be explained according to the drawings.

FIG. 1 is a block diagram of one embodiment.

1 is a crystal oscillation circuit, 2 is a frequency dividing circuit that divides the oscillation frequency obtained by the crystal oscillation circuit 1 to IHz, and 3 is IHz.
4 is a pulse sensor, 5 is an amplifier and a pulse rate counter, and 6 is a time counter that counts the time, date, etc. from the signal, and 6 is a counter that counts time, date signals, and pulse rate from the time counter 3 in response to control signals from the control unit 8. A gate and a decoder switch and decode the pulse rate signal from the pulse counting section 5 and input it to the display section 7, 7 is a display section, 8 is a control section, and 9 is a switch input section.

First, the oscillation frequency of the crystal oscillation circuit 1 is divided into IHz by the frequency divider circuit 2, and is input to the time counter 3 and counted. The time and date signals from time counter 3 are
Gate and decoder 6 according to control signals from control section 8
is inputted and displayed on the display unit 7 through the display unit 7, and used as a clock.

On the other hand, the control signal from the control section 8 is input to the pulse sensor 4, and the control signal from the control section 8 and an appropriate frequency of the frequency dividing circuit 2 are input to the amplifier and pulse rate counting section 5 as timing signals. A control signal is output from the control section 8 in response to a switch signal from the switch input section 9, and the output of the pulse sensor 4 is inputted to the gate and decoder 6 through the amplifier and pulse rate counter section 5. At this time, the gate and decoder 6 inputs a pulse rate signal to the display unit 8 in response to a control signal from the control unit 8 in place of the time and date signals, and the pulse rate is displayed.

Next, the pulse sensor 4, amplifier, and pulse rate counter 5 will be explained in more detail.

FIG. 2 is an external view of a part of the pulse sensor incorporated in the wristwatch, FIG. 3 is a sectional view thereof, and FIG. 4 is a detailed view of the light receiving section.

First, the pulse sensor uses a reflective photoplethysmogram detection method.
It includes a light emitting source 10 and a light receiving element 11, and is arranged below the display section I2 on the face of the watch, as shown in FIG. Furthermore, as can be seen from FIG. 3, the light emitting source 10 is also used as the illumination lamp L for the liquid crystal display section 13, and when measuring the pulse rate, the light from the lamp L is reflected on the mirror 14 and the case surface is illuminated. It is designed to be incident on the finger yagin F placed on the . Furthermore, as shown in FIG. 4, the light receiving section includes two sets of light receiving elements,
a, llb are arranged in parallel to the light emitting source 10, and the first light receiving element 11alC receives reflected light from the fingertip directly through the lens 15.
a, the reflected light from the fingertip is focused on the second light receiving element 11b by a lens 15b, and further filter I6
It is designed to be input through.

This filter 16 cuts a relatively long wavelength region, and light having a wavelength in a region that is not easily affected by absorption due to blood vessel pulsation is input to the second light receiving element 11b. Therefore, by comparing the outputs of the first light-receiving element 11a and the second light-receiving element 11b, it is possible to stably measure the pulse rate without being affected by noise caused by fluctuations in the fingertips.

Next, a method of counting the pulse rate will be explained with reference to a block diagram of the pulse sensor 4, amplifier, and pulse rate counter 5 shown in FIG.

10 is a lamp as a light emitting source; 17 is a control transistor; 18 is a control transistor on the light receiving side; 11a;
11b is a light receiving element, and a filter 16 is placed in front of the light receiving element Ilb.

In addition, these light-receiving elements (composed of phototransistors in the example)
Its collector is connected to the collector of the control transistor 18, and its emitter is connected to the power supply via a resistor 19,2°. Further, a control signal from the control section 8 in FIG. 1 is input to the base of each control transistor 17, 18. 21 and 22 are amplifiers, 23 is a comparator, 24 is a counting section, and 25 is an arithmetic section.

That is, when the control transistors 17 and 18 are turned on by the control signal from the control unit 8, the lamp 10 is lit.
The light enters the fingertip, and the reflected light from the fingertip goes to the light receiving element 11.
a, 'Ilb.

The light receiving element 11a receives both the fluctuation of light according to the pulse and the fluctuation of light due to the movement of the fingertip.
1b, the long wavelength side is cut off by a filter 16, and only the fluctuation of light caused by the movement of the fingertip is inputted. These signals are amplified by amplifiers 21 and 22, their levels are made equal, and then input to a comparator 23. The comparator 23 compares the signals, and only the pulse signal is input to the counter 24. Counting part 2
4, an appropriate frequency signal from the frequency dividing circuit 2 is input as a timing signal, and the time interval between the first pulse signal and the next pulse signal is counted, and the result is input to the calculation unit 25, and the unit is Converts to pulse rate per hour.

As mentioned above, although a light emitting source 10 having relatively wide band characteristics is used, the first. Second light receiving element 11a, I
lb and the configuration of the filter 16, the pulse can be detected stably and accurately.

Note that it is normally in the normal mode, and the time and date signals from the time counter 3 are inputted and displayed on the display section 7 through the gate and decoder 6 according to the control signal from the control section 8, and used as a clock.

And a mode changeover switch, for example, pushbutton S in Figure 2.
When m is turned on, this ON signal is input from the switch input circuit 9 to the control unit 8, the mode is switched, and the control signal is input to the pulse selector 4, amplifier and pulse rate counter 5, gate and decoder 6, Enters pulse rate measurement mode. That is, in this pulse rate measurement mode, the aforementioned control transistors 17 and 18 are turned on.

Here, when a finger is placed on a part of the sensor, the pulse is detected, counted by the amplifier/pulse rate counter 5, passed through the gate and decoder 6, and inputted and displayed on the display 7.

As explained above, the present invention includes a first light receiving element that detects a pulse wave and a second light receiving element that detects noise due to fluctuations in the fingertip through a filter. As the source, it can be configured using something with a relatively wide band characteristic, such as the illumination rung of the liquid crystal display section as shown in the embodiment, and it can be constructed at low cost, stably, and accurately at any place and at any time. A useful pulse rate detection sensor capable of detecting pulse rate can be provided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is an external view, Fig. 3 is a sectional view of the main part, Fig. 4 is a sectional view of another main part, and Fig. 5 is the same as Fig. 1. FIG. 2 is a block diagram showing main parts in more detail. 10... Light emitting source, 11... Light receiving element, Il
a...-first light receiving element, Ilb... second light receiving element, 16... filter. Agent Patent Attorney Aihiko Fukushi

Claims (1)

[Claims] 1. A light emitting source that irradiates light onto the fingertip for pulse detection, a first light receiving element that detects the pulse by receiving light reflected from the fingertip, and a filter that cuts light at relatively long wavelengths.
A second filter that receives reflected light from the fingertip through the filter.
A sensor for detecting a pulse rate, characterized in that a noise component of the first light receiving element is canceled by the output of the second light receiving element.