JPH0420403Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a cardiac sensor that detects as an electrical signal the change in inductance of a coil element of a sensor body in response to the displacement of a magnet fixed to the skin of a human body.

(Prior Art) Conventionally, cardiac sensors that detect chest wall vibrations or blood vessel site vibrations that occur with myocardial activity have been used that have semiconductor pressure sensing elements or piezoelectric elements. This conventional method involves manually pressing a sensor onto the carotid artery and femoral artery, and analyzing the signal waveform (cardiac diagram) in response to pressure changes caused by myocardial activity, or comparing the cardiac diagram with an electrocardiogram. Based on this, he diagnosed arteriosclerosis, various valvular diseases, etc. However, since the output signal of cardiac sensors using semiconductor pressure sensing elements or piezoelectric elements changes when the sensor is pressed against the skin, testing requires skill.

Cardiac sensors shown in FIGS. 5 to 9 have been developed to solve this drawback.
As shown in FIG. 5, this cardiac sensor has a magnet 3 attached to a part of the skin 2 corresponding to an artery 1 such as the carotid artery.
It is attached by adhering the adhesive thin film 4 covering this to the skin 2. A separate sensor body 6 is attached to the thin film 4 and magnet 3.
The magnet 3 is set in the bottom recess 8 of the outer case 7.
A shield case 9 made of non-magnetic metal is fitted, and an even number of coil elements 12 each having a winding 11 around a magnetic wire 10 are inserted in the shield case 9 radially and circumferentially as shown in FIG. The resin 13 is arranged at equal intervals (that is, so that the elements 12 facing each other across the center are in point-symmetrical positions).
A molded element stand 14 and a signal processing circuit 1 that processes the output signals of the element 12 group.
The signal processing circuit 1
A lead wire 17 is connected to the terminal 5 and is drawn to the outside.

As shown in FIG. 6, the connection of the winding 11 of the element 12 is divided into the solid line a and the dotted line b for each element 12, and the solid line a is connected to one of the DC power sources. The poles, for example, the positive electrode common terminal 18 side are connected to the outer end of each winding 11, and the negative electrode terminal 19 side is connected to the inner end of each winding 11, so that they are connected in series, and the connection indicated by dotted line b is
On the contrary, they are connected in series so that the positive electrode common terminal 18 side is connected to the inner end of the winding 11 and the negative electrode terminal 19 side is connected to the outer end of the winding 11.

The sum of the inductances of the two sets of elements 12 connected by these lines a and b differs depending on the position of the magnet 3. That is, as shown in FIG. 7, the magnetic flux Bφ generated in the element 12 by the current flowing through the line b and the magnetic flux Mφ caused by the magnet
However, with respect to the magnetic flux Aφ generated in the element 12 due to the current flowing through the wire a, the magnetic flux Mφ caused by the magnet 3 is biased in the forward direction, and the magnetic wire 10 is saturated, resulting in a difference in inductance. Note that, for example, the winding 11 connected to the wire b
If the winding direction of the magnetic wire 10 is reversed,
A current is passed through line b in the opposite direction to that shown.

As a circuit for detecting the difference in inductance depending on the position of the magnet 3, for example, a circuit as shown in FIG. 8 is used. That is, a winding group 11a connected to the wire a and a winding group 1 connected to the wire b.
One end of 1b is commonly connected to the power terminal 18 side,
The other ends are connected to the collectors of transistors 21 and 22, respectively, and the emitters of transistors 21 and 22 are connected to the other ends (ground) of the electrodes via resistors 25 and 26, respectively, and the bases of one of transistors 21 and 22 are connected to the other transistor 22,
By connecting the collector of transistor 21 to the collector of transistor 2 through parallel circuits 24 and 23 consisting of a capacitor and a resistor, an astable multivibrator is constructed.
The difference between the emitter voltages of magnets 1 and 22 is converted into a DC voltage by a high-cut filter (integrator circuit) 27, and the DC voltage is amplified by an amplifier circuit 28 to obtain an output voltage from an output terminal 29. The relationship between the position and the output voltage from the output terminal 29 is as shown in FIG. In other words, the closer the magnet is to the element 12, the higher the operating frequency of the multivibrator (for example, configured to vary in the range of 60kHz to 500kHz) and the higher the emitter voltage. L1 is uniquely determined
It is designed so that the linear region of ~L2 falls within the operating range of the magnet 3. Also, magnet 3 and element 1
The position No. 2 (operating point) is set at approximately the midpoint of the linear region of sensitivity, as shown in FIG. Furthermore, the responsiveness of the sensor can be changed by changing the time constant of the high-cut filter 27, and the time constant is determined by the frequency of change in the signal to be measured.

A sensor consisting of such radially arranged elements 12 cancels out the disturbance magnetic field, and the magnet 3
This has the advantage that the effects of uneven magnetization can also be canceled out.

In addition, as a conventional cardiac sensor,
As disclosed in Japanese Patent No. 155833, there is a structure in which measurements are made by loosely fitting a hole in the center of a sensor body into a magnet that is attached and fixed to the skin.

Note that since there is also a correlation between the distance of the magnet 3 and the operating frequency of the multivibrator, it is possible to obtain a signal corresponding to the malfunction frequency as a signal indicating the distance, but the signal processing circuit 15 The problem is that it becomes complicated.

(Problem that the invention aims to solve) The cardiac sensor that detects changes in inductance due to the movement of the magnet 3 as changes in electrical signals requires less skill than conventional sensors that detect pressure, etc. Although it has the advantage of not requiring
There was also a problem in that the sensor body 6 had to be held manually for about two minutes at most during the measurement.

Further, since the sensor main body 6 must be held by hand to position it relative to the magnet 3, there are problems in that positional deviation is likely to occur, measurement accuracy is poor, and skill is required. In addition, the above-mentioned Japanese Patent Publication No.
As disclosed in Publication No. 62-155833, a small magnet fixed to the skin has a structure in which the hole in the center of the sensor body is loosely inserted into the sensor body for measurement. It is difficult to fit the sensor because it is covered by the sensor body and must be fitted in the shade so that it cannot be seen from above. If the size was increased, the relative position of the magnet and the sensor body would shift, resulting in poor measurement accuracy.

In view of the above-mentioned problems, the present invention has developed a core sensor that eliminates the need to hold the sensor body by hand during measurement, which saves labor, and allows the sensor body to be easily and precisely set on the magnet. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a sensor for a cardiac sensor that detects as an electric signal the change in inductance of a coil element of a sensor body in response to the displacement of a magnet fixed to the skin of a human body. A ring-shaped holder into which the main body is removably inserted is provided, a thin film is fixed to the bottom surface of the holder, a magnet is fixed to the top surface of the film, and an adhesive is applied to the bottom surface of the film,
It is characterized in that a part or all of a release paper is attached to the adhesive so as to protrude outward from the outer periphery of the thin film.

(Function) When performing measurements using the cardiac sensor of the present invention, the release paper is peeled off from the holder and the holder is affixed and fixed to the skin using the adhesive provided on the film fixed to the bottom surface of the holder. Then, the sensor body is fitted into the holder to be held and measured.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In Figures 1 to 3, 3
0 is a sensor body, and 38 is a resin holder to which the magnet 3 is attached with the following structure. Holder 38
A plurality of (preferably 4 or more, 8 in the illustrated example) are arranged around the ring-shaped bottom plate portion 39.
A rising piece 40 is provided, and a locking protrusion 40a protruding inward is formed on the top of each rising piece 40 to lock a protrusion 32a formed around the resin case 32 of the sensor main body 30. ing.

Further, on the upper surface of the bottom plate portion 39 of the holder 38, three or more (eight in the illustrated example) protrusions 41 are formed to abut and support the bottom surface of the case 32. Further, the lower surface of the bottom plate portion 39 is coated with an adhesive 42.
A stretchable thin film 43 made of nonwoven fabric, a resin film, or the like is fixed, and the magnet 3 is fixed to the center of the upper surface of the thin film 43 with an adhesive 44. These thin films 43 and magnets 3 may be fixed by heat welding. Further, an adhesive 45 is applied to the lower surface of the thin film 3, that is, the surface facing the human skin, and the coated surface is covered with a release paper 46. It has a tongue piece 46a to facilitate peeling. As the thin film 3, it is preferable to use a nonwoven fabric made of urethane resin because it has no stretching direction and is flexible.

As shown in FIG. 3, the sensor main body 30 of this embodiment has an even number of elements 12 each having a winding 11 wound around a magnetic wire 10 on one surface of the substrate 16, that is, the surface facing the magnet 3. , as described above, are arranged radially and at equal intervals in the circumferential direction so that corresponding parts across the center are point symmetrical and molded with resin 47, thereby preventing relative movement of the elements 12 with respect to the substrate 16. In addition, the signal processing circuit 15 of the element 12 is provided on the opposite side of the board 16, and the signal processing circuit 15 is covered with a shield case 31 made of a non-magnetic material such as brass or aluminum. The lead wire 17 connected to the signal processing circuit 15 is pulled out from the case 32, and the element 12, the substrate 16, and the shield case 31 are integrated with resin, thereby forming the sensor body 30 and achieving a thinner design. ing. Further, a lead wire accommodating portion 48 through which the lead wire 17 is passed is formed on the upper surface of the case 32 to protrude upward and extend in the radial direction.
As shown in FIG.
0 to facilitate gripping by the sensor body 30.
This contributes to the miniaturization of the product and reduces costs.

In the sensor of this embodiment, the adhesive 45 coated on the thin film 43 is exposed by holding the tongue 46a of the release paper 46 shown in FIGS. 1 and 2 and peeling it off. carotid artery or femoral artery)
The holder 38 is attached to the skin together with the thin film 43 so as to be positioned on top of the sensor body 30.
8 and measure. At this time, the bottom surface of the case 32 comes into contact with the protrusion 41, and at the same time, the bottom surface of the case 32
The protrusion 32a around the locking protrusion 4 of the rising piece 40
By being elastically locked to 0a, the magnet 3 is positioned at the center of the element 12, and as the skin 2 in that area moves in and out as the artery 1 moves, the magnet 3 follows and moves. Based on the principle described above, the signal processing circuit 15 outputs an output corresponding to the position of the magnet 3 via the lead wire 17 to a measuring device (not shown).

In the above embodiment, the release paper 46 was provided with a tongue piece 46a with a part thereof protruding from the thin film 3, so that the release paper 46 could be easily peeled off.
As shown in the figure, if the release paper 46A is made larger than the thin film 43, the release paper can be peeled off more easily.

(Effects of the invention) As described above, the present invention includes a ring-shaped holder into which the sensor body is removably fitted, a thin film is fixed to the bottom surface of the ring-shaped holder, and a magnet is fixed to the top surface of the thin film. Then, an adhesive was applied to the lower surface of the thin film, and a release paper was attached to the adhesive, so measurements were performed by peeling off the release paper, attaching a holder to the skin, and fitting the sensor body to the holder. Since it is possible to do this, at the time of measurement,
There is no need to hold the sensor body by hand as in the past, resulting in labor savings. Also,
Since the sensor body is fixed by being fitted into the holder with the magnet attached, there is no camera shake that occurs when holding the sensor body in your hand, and the positioning accuracy of the sensor body relative to the magnet is improved, making it easier for unskilled people to measure. It is possible to perform stable measurements even when there is a problem, and the measurement accuracy is improved.

In addition, if the conventional structure is such that the center hole of the sensor body is loosely fitted into the magnet fixed to the skin, when the magnet is fitted into the hole of the sensor body, the magnet is hidden behind the sensor body and cannot be seen visually. However, according to the present invention, the holder is ring-shaped and the sensor body is fitted into it, so when attaching the sensor body to the holder, the sensor body is attached to the holder. Since the position of the sensor body can be visually confirmed at any time even from above, the sensor body can be easily attached to the holder.

Furthermore, since at least a portion of the release paper is provided to protrude from the outer periphery of the thin film, the release paper can be easily peeled off.

Furthermore, since the holder is disposable, it is hygienic and prevents skin infections.

Furthermore, by preparing holders to which thin films of different thicknesses and hardnesses are fixed, it is possible to measure different parts using the same sensor body.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the cardiac sensor according to the present invention with the holder and sensor body separated, Fig. 2 is an exploded side view of the holder of the embodiment, and Fig. 3 shows the cardiac sensor of the embodiment in the holder. FIG. 4 is a plan view showing another example of the holder of the present invention, FIG. 5 is a sectional view showing a conventional cardiac sensor, and FIG. A plan view showing the arrangement of elements of a conventional cardiac sensor; FIG. 7 is an explanatory diagram of the operation of the elements; FIG. 8 is a circuit diagram showing an example of the signal processing circuit of the elements; FIG. 9 is a diagram showing the distance between magnets and signals. FIG. 3 is a relationship diagram with the output voltage of the processing circuit.

Claims (1)

[Claims for Utility Model Registration] 1. A cardiac sensor that detects changes in inductance of a coil element of a sensor body as an electrical signal in response to displacement of a magnet fixed to the human skin, which includes a ring-shaped holder into which the sensor body is removably fitted. A thin film is fixed to the lower surface of the holder, a magnet is fixed to the upper surface of the film, an adhesive is applied to the lower surface of the film, and a part or all of the release paper is attached to the outer periphery of the thin film. The heart sensor is characterized by being affixed in a manner that projects further outward. 2 Utility model registration claim 1, characterized in that the thin film is made of a nonwoven fabric made of urethane resin.
Cardiac sensor as described in section.