JPH0524776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a position sensor that detects displacement information of a magnetic body attached to a detection target.

[Technical background of the invention and its problems]

Conventionally, a position detection device (hereinafter referred to as a position detection device) detects a position by fixing a permanent magnet, which is a magnet generating body, to a detection target and detecting its magnetic displacement by a detection section installed at a predetermined distance from the detection target. 2. Description of the Related Art Position sensors) have been proposed, and are particularly suitable for detecting the movement of living organisms such as humans.

However, when the detection unit is suspended from a permanent magnet fixed to a living body, etc., which is the detection target, that is,
It is preferable to install it in an absolute space, but if the detection unit is installed completely away from the living body, there is a problem that if the living body moves unexpectedly, it will not be able to correspond with the permanent magnet, which will deteriorate detection accuracy. This made positioning and mounting of the magnetizing body and detection part difficult, and the practical value was low.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is easy to install, maintains the correspondence between the magnetizing body and the detection unit even if the detection target moves unexpectedly, and improves detection accuracy. The object of the present invention is to provide a position sensor that does not reduce the

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention includes a detecting section consisting of two equivalent magnetic cores or two magnetic cores in which at least two coils are wound around one or two high magnetic permeability magnetic cores, and a signal obtained from this detecting section. A position sensor comprising a detection circuit for processing and a magnetic body installed on a detection target, which is attached to the detection target via a vibration isolating member, the detection unit being spaced at a predetermined distance from the magnetic body. The present invention is characterized in that it includes a positioning member for positioning while maintaining the magnetic field, and a fixing member for fixing the magnetic body to the detection target.

[Embodiments of the invention]

The present invention will be specifically explained below using Examples.

FIG. 1 is a schematic diagram of an embodiment of the apparatus of the present invention.
This device includes a permanent magnet M as a magnetic body fixed to the surface of a living body 8 to be detected, a detection section 1 installed at a predetermined distance from the permanent magnet M, and a signal from the detection section 1. It includes a detection circuit 2 that processes and outputs an output Eout. The detection section 1
For example, amorphous amorphous wire AF (composition Co ₆₈ Fe ₄ Si ₁₃ B ₁₅ at%, 110 μm) is a 40 mm long high permeability magnetic core.
It consists of two coils H _1T and H _2T wound the required number of times N on both ends of the permanent magnet M, for example,
It has a disk shape with a diameter of ~3 mm, and is fixed to the surface of the living body 8 with an adhesive or the like via a synthetic resin disk 7 that is a fixing member with a diameter of 10 mm. The detection section 1 is attached to the surface of the living body 8 via positioning members 3, 4, 5, and 6, and is positioned so that the tip of the detection section is kept at a predetermined distance from the permanent magnet M. The positioning member includes a glass tube 3 in which the detection section 1 is fixed, a bowl-shaped synthetic resin frame 4 fixed to the glass tube 3 via a rubber 5 serving as a vibration isolator, and this synthetic resin frame. 4 and a rubber 6 serving as a vibration isolating material to fix the body 8 to the surface of the living body 8.

With this configuration, since the permanent magnet M is fixed to the surface of the living body 8 via the synthetic resin plate 7, it is extremely easy to fix it, and it moves following the movement of the living body, whereas the detection unit 1 2 pieces of vibration isolating material 5, 6
is connected to the living body 8 via the positioning member inserted, so small movements of the living body (movements that should be detected) are absorbed by the rubbers 5 and 6 and are not transmitted. This means that while the displacement information of the permanent magnet can be accurately detected, the correspondence between the permanent magnet and the permanent magnet due to the careless movement of the living body can be maintained.

This will be explained using experimental data shown in FIG. Figure 2 shows measurement data when a position sensor is attached to the human body to be measured and the body is rocked back and forth while sitting on a chair.
(and 5), when installed without intervening the vibration isolating material (b) in the same figure.

Note that the present invention is not limited to the above configuration, and various modifications can be made.

For example, the detection unit 1 is not limited to two equivalent magnetic cores;
A two-core configuration may be used, in which amorphous wires are arranged in a straight line at predetermined intervals and the coil is wound around each of the amorphous wires.

Further, the shape of the permanent magnet, the fixing member, or the positioning member is not limited to a circular shape, but may be a square shape or the like.

Furthermore, only one of the vibration isolators 5 and 6 may be used.

Next, an application example of detecting displacement information of a living human body using the device will be described with reference to FIG. 3 and subsequent figures. Note that although a combination of a multivibrator circuit and an active filter is shown here as a specific configuration of the processing circuit 2, the active filter is not an essential component.

In FIG. 3, 1 is the detection section, and the signals obtained from both ends of the detection section are transmitted via signal lines l ₁ and l ₂ to transistors Tr ₁ and Tr ₂ and signal lines l ₃ and l ₄ to the active filter ACF. It is now input to . The outputs of the commutation circuits (consisting of capacitor C _B and resistor R _B ) connected to each signal line l ₁ and l ₂ are crossed and applied to the base of each transistor Tr ₁ and Tr ₂ . There is. In addition, load resistors R _L and R _L are connected in series between the signal lines L ₃ and L ₄ ,
A variable resistance VR is connected in parallel with this, and this resistance
The connection point between VR and the resistors R _L and R _L is commonly grounded. Note that a power supply voltage E is applied between the coils H _1T and H _2T , and the active filter ACF
The output Eout can be obtained from . That is,
This circuit is constructed as a multivibrator bridge using two equivalent magnetic cores. It should be noted that each magnetic core in the two magnetic cores is selected to operate in a rotating magnetization region.

In addition, the active filter ACF allows selection of filter characteristics, such as cutting frequencies above 50Hz, cutting frequencies above 20Hz, cutting frequencies below 20Hz,
Various modes can be selected, such as passing through both the DC ~ 20Hz band and the 20Hz ~ 50Hz band.

When a micromagnet M is placed near the coil in a circuit with such a configuration and is moved relative to the coil _H2T , the moving distance X (mm) and the output Eout
(mV) is as shown in Figure 4. In the same figure, N ₁ to _{N 3} are the changes in the number of turns of the coil, N ₁ = 150 (Turns), N ₂ = 300 (Turns),
N ₃ =450 (Turns), and the current supplied to the coil I = 100 (mA). Further, the micro magnet M used was one having a diameter of 3 mm and a height of 1.5 mm.

As is clear from the figure, the detection sensitivity increases as the function N increases. In both cases, linearity is maintained up to a large displacement of 6 mm (nonlinearity < 1% FS).
, and the displacement of the magnet can be detected accurately.

The results of detecting biological information using the device will be explained.

FIG. 5 shows the fixed position of the permanent magnet M by the device (hereinafter also referred to as sensor), and shows the periphery of the human body P including the heart at six points (A to F) in the vertical direction.
Divided into a matrix of 6 points (1 to 6) in the horizontal direction.
It attempts to detect cardiac displacement information regarding 36 points. Note that point A-3 corresponds to the base of the heart, and point F-2
corresponds to the apex of the heart. Moreover, the E-2 point corresponds to the groove drop. In this case, micromagnets may be attached to all of the points, or a single magnet may be attached for each measurement.

The results are shown in FIG. This data was obtained with active filter AF operating at 5-50Hz. In the figure, since the waveform at point B-6 seems to contain various information, various analyzes were performed based on the information at this position, and the results shown in FIG. 7 were obtained.

Fig. 7a shows a waveform obtained by preparing an electrocardiograph separately from the device of the present invention and obtaining an electrocardiogram at point B-6, and Fig. 7b shows the cardiac displacement at point B-6 in Fig. 4. FIG. 2 is a diagram (that is, a diagram directly showing the output of the sensor according to the present invention). Figure c is a waveform obtained by obtaining information from DC to 20 Hz through a filter that cuts out components of 20 Hz or more in the cardiac displacement diagram waveform.
Figure d shows a waveform of 20Hz to 50Hz obtained by cutting out the components of 20Hz or less in the heart displacement diagram waveform.

As a result of examining the waveform shown in FIG. 7c, it was found that it almost coincided with the pulsation diagram.

As a result of examining the waveform in d of the same figure, it was found that it almost coincided with the phonocardiogram. In other words, the first peak is the th sound (a sound that occurs as the ventricles contract, which is a combination of the ventricular contraction sound and the atrioventricular valve sound), and the second peak is the th sound (the sound that occurs as the ventricles relax). The sound is the closing sound of the aortic valve).

Based on the above results, the base of the heart (point A-3)
When the waveforms at the heart apex (point F-2) were analyzed, the results shown in FIGS. 8 and 9 were obtained.

Figures 8a and 9a show electrocardiograms, Figures 8b and 9b are phonocardiograms obtained by applying a 20-50Hz bandpass filter, and Figures 8c and 9c are 20Hz. ~
Phonocardiograms obtained by applying a 30 Hz band pass filter, Figures 8 d and 9 d are obtained by applying a 30 to 40 Hz band pass filter, and Figures 8 e and 9 e are 40 to 40 Hz band pass filters.
It is a diagram obtained by applying a 50Hz bandpass filter.
Moreover, FIG. 8 f and FIG. 9 f are pulsatograms obtained by applying a 0 to 5 Hz filter.

As is clear from both figures, if the components included in the range of 20 to 50 Hz are extracted from the obtained heart displacement diagram, clear phonocardiograms as shown in each figure b and b can be obtained.
When components in the range of 0 to 5 Hz were extracted, clear basal and apical pulsatograms could be obtained as shown in each figure f.

From the above, it can be seen that the sensor output shown in FIG. 7b is a heart sound wave of 20 Hz or more superimposed on a pulsation wave of about 20 Hz or less. Therefore, even if you look at the biological information (for example, Figure 7b) as it is, you will not be able to obtain any living information (or useful information). Figure and DC ~ approx.
It can be seen that it is important to collect data separately into pulsatograms between 20 Hz.

The biological information obtained from a desired position using the device of the present invention as described above is hereinafter referred to as a cardiac diagram. By applying a filter of a desired value to a cardiac diagram obtained from a desired position, a heartbeat diagram and a phonocardiogram can be easily obtained. Moreover, by obtaining a cardiac diagram of each point in a matrix over a wide range, it is possible to obtain effective information as described below.

FIG. 10 shows the time course of the displacement distribution of the chest wall due to pulsation using contour line changes. Each measurement value is not measured simultaneously, but the instantaneous value of the pulsation wave at each measurement point is read based on the R wave of the electrocardiogram. The pulsation waves and electrocardiograms of healthy people at rest are regular and the reproducibility of each cycle is high, so the contour lines in the diagram are approximated when each measurement point is measured simultaneously. Figure a shows the case at the same time as the ECG R wave, and b to d.
indicates the case where the time passes sequentially every 0.2 seconds. The reference value (0 value) of displacement was the minimum value of each pulsating wave. In Figure a, the area near the left atrium is elevated by 15 to 20 μm, and in Figure b, three locations near the left ventricle are elevated by more than 15 μm, with the highest value being 25 μm. In c, a pattern similar to a is again shown, in d the raised points extend to the left ventricular side, and in e the pattern is again similar to a. Conventional pulsagrams using a microphone measure chest wall vibration pressure, and this pressure is the sum of vibrations over an entire circular area with a diameter of 5 cm, making it difficult to detect local displacements of the chest wall. , local displacement is detected in the magnet sensor of the present application. In this case, there is a possibility that the sensor core fixing frame itself, which has a diameter of 3 cm, vibrates, but since the pulsation is a local phenomenon, the pulsation transmitted to the bottom of the approximately 10 cm long ring frame is smoothed out. , it is thought that a DC component appears as a bias in the sensor output. Therefore, these pulsatograms are based on the sensor output.
Only the 0.5 to 5 Hz component was used.

In this way, by obtaining biological information in a matrix as shown in FIG. 5 using the detection device of the present invention, it is also possible to specify the site of a heart defect by, for example, measuring the area around the heart. Naturally, it is also possible to check the state of cardiac function.

The present invention is not limited to the embodiments described above, and various modifications are possible.

Although the above embodiment detects the displacement state of the heart, it goes without saying that it can be applied to other parts as well.

Figures 11a and 11b show carotid wave and wrist measurement data before exercise, and Figures 12a and 12b show carotid wave and wrist measurement data after exercise. In either case, the results are almost the same as those detected by existing pulse wave meters, indicating that the pulse waves are faithfully reproduced.

〔Effect of the invention〕

As described in detail above, in the present invention, the magnetizing body is fixed to the detection target via a fixing member having a wider area than that, so fixing is easy, and the detection part is isolated from the magnetizing body for a predetermined period to prevent Because it is fixed to the detection target using a positioning member via a vibrating member, it is easy to install, and the relative position of the detection target to the magnetic body can be maintained without changing due to careless movement of the detection target. Since the movement based on the information to be detected is not directly transmitted to the detection unit, highly accurate detection can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the device of the present invention, FIGS. 2a and b are measurement data for explaining the effects of the present invention, and FIG. 3 is a circuit diagram showing an example of application of the device of the present invention. 4 is a characteristic diagram thereof, FIG. 5 is a front view for explaining the detection points of the device, FIG. 6 is displacement data at each point obtained by the device, and FIG.
The diagram shows an electrocardiogram, a cardiac displacement diagram, an electrocardiogram corresponding to an electrocardiogram, and a phonocardiogram when analysis is performed based on the data at a specific point in Figure 6. Figures 8 and 9 both show data at a specific point in Figure 6. FIG. 1 is a diagram for performing various analyzes based on . In each diagram, a is an electrocardiogram, b to e are phonocardiograms for each frequency component, and f is a pulsatogram. FIGS. 10 a to 10 e are temporal transition diagrams of chest wall displacement distribution due to pulsation. FIGS. 11a and 11b show detection data for the carotid artery and wrist before exercise, and FIGS. 12a and 12b show detection data for the carotid artery and wrist after exercise. DESCRIPTION OF SYMBOLS 1...Detection part, 2...Processing circuit, 3, 4...Positioning member, 5, 6...Vibration isolating member, 7...Fixing member, 8...Detection target, _H1T , _H2T ...Coil wound on equivalent two-core amorphous , M... Magnetizing body, Tr ₁ , Tr ₂ ... Transistor, ACF... Active filter.

Claims (1)

[Scope of Claims] 1. A detection section consisting of two equivalent magnetic cores or two magnetic cores in which at least two coils are wound around one or two high permeability magnetic cores, and a detection circuit that processes signals obtained from this detection section. and a magnetic body installed on the detection target, which is attached to the detection target via a vibration isolating member, and the detection unit is positioned at a predetermined distance from the magnetic body. A position sensor comprising: a positioning member for fixing the magnetic body to a detection target; and a fixing member for fixing the magnetic body to a detection target. 2. The position sensor according to claim 1, wherein the vibration isolating member is made of rubber. 3. The position sensor according to claim 1 or 2, wherein the magnetizing body is a permanent magnet, and the fixing member is a synthetic resin member having a larger area than the permanent magnet. 4. The position sensor according to claim 3, wherein the synthetic resin member is an adhesive tape.