JP2000060844A - Sheet for mounting biological sound detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for mounting a biological sound detector for reducing the feeling of incompatibility at the time of mounting the biological sound detector and suitably detecting biological sound by the biological sound detector. SOLUTION: By interposing a soft sheet 76 provided with viscosity almost similar to the skin 11 between a flexible resin film 36 and the skin 11, the feeling of the incompatibility at the time of mounting a heart sound detector is reduced. Further, since body hair 78 on the surface of the skin 11 with which the flexible resin film 36 is in contact is covered with the soft sheet 76 without a clearance, that is since an air layer is not formed between the flexible resin film 36 and the skin 11, heart sound waves are not reflected on the boundary surface of the air layer. Since the intrinsic acoustic resistance R of this sheet for mounting is closer to the intrinsic acoustic resistance R of the skin 11 than the intrinsic acoustic resistance R of air, the reflection of heart sound on the boundary surface of the skin 11 and the soft sheet 76 is relatively little and thus, the reduction of the heart sound detected by the heart sound detector due to the hairiness of a living body is suitably prevented.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to the detection of body sounds occurring in a living body to diagnose diseases such as the heart and respiratory system of the living body. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a body sound detection device that outputs a body sound signal representing sound, and more particularly to a technique for detecting a body sound in a more suitable state for the body sound detection device. [0002] For example, in order to diagnose a disease of a living body such as a heart disease or a respiratory system, it is mounted on the skin of a predetermined portion of the living body and heart sounds, respiratory sounds, and pleural sounds generated in the living body. 2. Description of the Related Art Diagnosis is performed using a body sound detection device that detects body sounds such as arterial sounds and bowel sounds and outputs a body sound signal representing the body sounds. For example, a heart sound is detected by a heart sound detection device mounted on the skin of the chest to measure a heart sound chart, and a heart disease is diagnosed from the heart sound chart. If a patient has a heart disease, the heart sound chart obtained by measuring the patient contains heart murmurs caused by the heart disease in addition to the normal heart sound, so the heart disease is diagnosed. You can do it. [0003] The above-mentioned body sound detecting device detects the vibration of the skin caused by the transmission of the sound wave of the body sound, that is, the body sound wave, to the skin. Vibration of the skin is transmitted to the air inside the body sound detection device, and is transmitted to an air conduction type that detects body sound based on the vibration of the air, or to a member of the body sound detection device that is brought into contact with the skin of a living body. There is a direct conduction type that detects body sounds based on the vibration of one of the members. In the air conduction type body sound detection device, in order to obtain a body sound signal having a high gain, an opening of a housing that is brought into contact with the skin of a body is closed with a relatively hard flexible film. Detection devices have been proposed. For example, this is the heart sound detection device described in Japanese Patent Application No. 9-120531 previously filed by the present applicant. According to this heart sound detection device, since it is of the air conduction type, it has the advantage of being less aging and being more robust than the direct conduction type body sound detection device, and has the advantage that the opening is closed. As a result, an acoustic room is formed, so that a body sound signal with a high gain can be obtained. [0005] However, since the flexible film is made of a relatively hard material, for example, a relatively hard resin, it gives a sense of incongruity to the subject when worn. [0006] Further, there is a case where an air layer is formed between the flexible film and the skin due to the presence of body hair between the flexible film and the skin. On the other hand, a sound wave has a property of being partially reflected at a boundary surface between two media, and the reflectance increases as the difference between the specific acoustic resistances R of the two media increases. Here, the specific acoustic resistance R is a product of the density ρ of the medium and the sound velocity c in the medium. Therefore, when the air layer is formed, a part of the body sound is reflected when transmitted from the skin to the air layer and when transmitted from the air layer to the flexible membrane, and the body sound is detected. There has been a problem that the body sound detected by the device is reduced. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the discomfort when the body sound detection device is mounted and to provide the body sound detection device with the body sound. It is another object of the present invention to provide a mounting sheet for a body sound detection device, which is suitably detected. SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to provide a housing having an opening at the bottom, the opening being brought into close contact with the skin of a living body, and the opening. A body sound detection device which is provided on a skin of a living body, including a relatively hard flexible film for closing a portion, and a microphone provided in the housing for converting vibration of the diaphragm into an electric signal; A mounting sheet for a body sound detection device interposed between the skin of a living body, and a hard sheet substantially interposed between the flexible membrane and the skin of the living body and substantially similar to the skin of the living body. Is to have. According to the present invention, since the mounting sheet having substantially the same hardness as the skin of the living body is interposed between the flexible film and the skin, the body sound can be detected. The uncomfortable feeling at the time of mounting the device is reduced, and further, the hair on the surface of the skin that the flexible membrane contacts is covered with the mounting sheet without gaps,
That is, since an air layer cannot be formed between the flexible film and the skin, biological sound waves are not reflected at the boundary surface of the air layer, and the density of the mounting sheet is smaller than the density of the air. And the sound velocity in the mounting sheet is closer to the sound velocity in the skin than the sound velocity in the air, that is, the specific acoustic resistance R of the mounting sheet is greater than the specific acoustic resistance R of air.
Is closer to the specific acoustic resistance R of the skin, and the reflection of the body sound at the interface between the skin of the living body and the mounting sheet is relatively small. A decrease in the detected body sound is suitably prevented. According to another aspect of the present invention, preferably, the mounting sheet for the body sound detecting device has substantially the same value as that of the skin of the living body in at least one of density and sound velocity in a medium. Things. With this configuration, since the specific acoustic resistance R of the mounting sheet is closer to the specific acoustic resistance R of the skin of the living body, the reflection of the body sound at the interface between the skin of the living body and the mounting sheet is further reduced. In addition, a decrease in body sounds detected by the body sound detection device due to hairyness of the living body can be prevented more suitably. Preferably, the mounting sheet is affixed to a surface of the flexible film that contacts the skin. This eliminates the need for the mounting sheet to be interposed between the flexible film and the skin for each measurement. Preferably, the mounting sheet is interposed between the surface of the living body sound detecting device that comes into contact with the skin of the living body and the skin. According to this configuration, in addition to the skin contact surface of the flexible membrane, the mounting sheet is interposed between the contact surface of the body sound detection device that contacts the skin of the living body and the skin. The uncomfortable feeling when the body sound detecting device is mounted is further reduced. Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing the appearance of a heart sound detecting device 10 to which the present invention is applied and detects heart sounds as body sounds. FIG. 2 is a cross-sectional view for explaining the structure of the heart sounds detecting device. A cross-sectional view of the heart sound detection device 10 placed at a predetermined heart sound detection site on the central epidermis 11 is shown. 1 and 2, a heart sound detecting device 10 is made of a relatively hard material such as an ABS resin, and has a flat cylindrical upper housing 12 that is open in one direction. And a flat cylindrical lower housing 14 that is open in both directions, an annular projection 16 provided on the opening side of the upper housing 12, and a lower housing 14.
By fitting with an annular projection 20 provided in the opening on the side where the bottom 18 is not provided, a casing 22 on a flat cylinder that opens in one direction as a whole is formed. The bottom portion 18 of the lower housing 14 has a relatively large circular hole 24 at the center, and the surface of the bottom portion 18 opposite to the side where the upper housing 12 is located is on the side to be brought into contact with the epidermis 11 of the living body. It becomes the face of. The upper housing 12 and the lower housing 14
Is formed of a soft member such as silicon rubber on the bottom portion 18 of the lower housing 14, the outer diameter is equal to the inner diameter of the housing 22, and the inner diameter is smaller than that of the bottom portion 18. An annular vibration absorber 28 slightly smaller than the diameter of the circular hole 24 is fitted to absorb vibration from the lower housing 14. Further, the surface of the vibration absorber 28 opposite to the bottom 18 is made of a relatively hard resin.
Circular edge 2 whose diameter is slightly shorter than the inner diameter of housing 22
9, and a dish-shaped member 32 having a central portion of the edge portion 29 and a convex portion 30 having an outer diameter equal to the inner diameter of the vibration absorber 28, the convex portion 30 forming a hole in the center of the vibration absorber 28. It is fitted so as to penetrate. A tapered sound collecting hole 34 whose diameter becomes smaller toward the bottom is formed on the surface 11 side of the convex portion 30 of the dish-shaped member 32, and the collecting hole 34 opens substantially parallel to the opening of the lower housing 14. The opening of the sound hole 34 on the skin 11 side is closed by a relatively hard flexible resin film 36 which has a cap shape and is fitted on the side wall surface of the projection 30. The flexible resin film 36 is the same as the flexible resin film provided on the pressing surface of the flat pressing portion of the stethoscope, such as a polyvinyl chloride resin having a thickness of about 0.1 mm. An acoustic chamber is formed inside. On the side of the protruding portion 30 of the dish-shaped member 32 opposite to the skin 11, a cylindrical member 38 is provided, so that a housing chamber 42 for housing the microphone 40 is formed. On the end face of the cylindrical member 38 on the sound collecting hole 34 side, a circular vibration absorbing sheet 46 having a through hole 44 having a diameter smaller than the diameter of the microphone 40 at the center is provided on the opening surface of the sound collecting hole 34. It is fixed substantially horizontally with respect to. Further, the accommodation room 4 of the vibration absorbing sheet 46
On the side opposite to 2, a circular chamber 47 that is thinner in the thickness direction than the vibration absorbing sheet 46 is formed in order to enable vibration perpendicular to the plane direction of the vibration absorbing sheet 46. The vibration absorbing sheet 46 is made of a vibration absorbing material such as butyl rubber.
In the state where the vibration is not propagated, the stress in the thickness direction is required to the extent that the vibration absorbing sheet 46 is not bent by the weight of the microphone 40, so that the thickness is preferably 1.0 to 2.0 mm. When the vibration propagates to the vibration absorbing sheet 46, the vibration absorbing sheet 46 vibrates perpendicularly to the surface direction and absorbs the propagated vibration, and functions as a low-pass filter that suitably removes particularly the vibration of 50 Hz or less. And
The frequency of heart sounds is 50Hz or more (for example, II sound is 100 ~
150 Hz), the heart sound can be detected in a suitable state from which noise on the low frequency side has been removed. The microphone 40 is fixed by an adhesive or the like so as to cover the through hole 44 of the vibration absorbing sheet 46 in the accommodation room 42, and a microphone case 48 opening to the through hole 44 side, and a microphone case 48 A vibrating plate 50 housed in the through hole 44 side so as to be parallel to the vibration absorbing sheet 46 and functioning as an electrode;
A fixed electrode 52 facing the diaphragm 50 with a slight gap of about 0.01 to 0.05 mm;
8, a capacitive microphone comprising a pair of connection terminals 56 connected to the conducting wire 54 on the side opposite to the through hole 44 and an insulating member 58 for insulating the pair of connection terminals 56 from each other. When the diaphragm 50 is vibrated, a heart sound from the skin 11 is detected, and a heart sound signal representing the heart sound is output. The surface of the dish-shaped member 32 opposite to the side in contact with the vibration absorber 28 is in contact with the weight 60. The weight 60 is made of a material having a relatively high specific gravity, such as lead, copper, or iron, and preferably has a weight of about 80 to 150 g.
It has a flat cylindrical shape whose diameter is equal to the diameter of the edge portion 29 of the dish-shaped member 32, and is located at the center of the surface opposite to the side in contact with the dish-shaped member 32, that is, the surface facing the inner plane 62 of the upper housing 12. A vibration absorber 64 made of the same material as the vibration absorber 28 is fixed between the upper housing 12 and the central portion of the inner flat surface 62 of the upper housing.
In addition to absorbing the vibration from, the weight 60 is held between the vibration absorber 28 and the vibration absorber 64 in a floating state, whereby the displacement of the weight 60 is suppressed. Since the weight 60 is made of a material having a relatively heavy specific gravity as described above and has the above-mentioned weight, noise from outside the living body is blocked by the weight 60, and the heart sound detecting device 10 is a suitable constant. Presses the skin 11 of the living body with the pressing force of
A heart sound signal with stable reproducibility can be detected. further,
Since the resonance frequency of the entire heart sound detection device 10 is in a lower frequency range than the frequency of the heart sound, the energy of the heart sound from inside the living body is not consumed as the energy for vibrating the body sound detection device 10, so that the heart sound is not generated. Microphone 4
0 is efficiently detected. The diameter of the weight 60 and the diameter of the edge portion 29 of the dish-shaped member 32 are slightly shorter than the inner diameter of the housing 22 as described above.
Since the vibration absorber 64 is fixed between the housing 22 and the housing 2, a closed air chamber 66 is formed between the housing 22 and the weight 60 and the dish-shaped member 32. Environmental noise from outside the living body is reflected at the boundary between the closed air chamber 66 and the housing 22 or is absorbed without resonance in the air chamber 66, so that the environmental noise is inside the air chamber 66. Detection by the provided microphone 40 is suppressed. The tapered sound collecting hole 34 and the accommodation chamber 42
Is communicated by a communication passage 68 having one end communicating with the tapered sound collecting hole 34 and the other end communicating with the housing chamber 42. Since the holes 70 are provided and the pressure on both sides of the diaphragm 50 is adjusted to be the same, only the fluctuation component (AC component) of the pressure in the tapered sound collection hole 34 is detected by the microphone 40. . The conducting wire 54 connected to the connection terminal of the microphone 40 passes through the hole 72 provided in the dish-shaped member 32 and a part of the weight 60, and passes through a through hole 74 provided in the side surface of the housing 22. Is connected to a connection terminal 76 at the tip of a cord 75 inserted into the cable. Further, a soft sheet 77 is attached to the surface of the flexible resin film 36 on the side to be brought into contact with the skin 11. The soft sheet 77 constitutes the mounting sheet of the present embodiment, and has a thickness of, for example, about 0.5 to 2.0 mm, and has a thickness of, for example, 1 ° to about JIS A type spring hardness tester. An elastic body or a gel-like viscous body having a hardness of about 15 ° and substantially the same as that of a human skin and a density similar to that of the skin 11. Due to the presence of the soft sheet 77, the uncomfortable feeling when the heart sound detection device 10 is mounted on the skin 11 can be reduced, and the body hair 78 on the skin 11 can be covered. That is, the flexible resin film 36 and the skin Since no air layer is formed between the air layer and the heart, no heart sound from the inside of the living body is reflected by the air layer. Further, since the soft sheet 77 has a density substantially similar to the density of the skin 11, it can be considered that the specific acoustic resistance R of the soft sheet 77 and the specific acoustic resistance R of the skin 11 are relatively equal. Since the reflection can be made at the boundary surface between the skin 11 and the soft sheet 77 and the soft sheet 77 is relatively thin as described above,
Since the absorption of the heart sound in the heart sound 7 is small, the decrease of the heart sound propagating from the skin 11 into the heart sound detection device 10 is suppressed. Further, the bottom portion 18 of the lower housing 14
On the surface on the side of the skin 11, an annular soft sheet 80 made of the same material as that of the soft sheet 77 and substantially the same as the surface of the bottom 18 on the side of the skin is adhered. The annular soft sheet 80 reduces the uncomfortable feeling when the heart sound detection device 10 is mounted on the skin 11 and the lower housing 1
8 more effectively blocks environmental noise that propagates through the living tissue and reaches the heart sound detection device 10 than when it is directly attached to the skin 11. Furthermore, even if there is some unevenness in the skin 11 at the site where the heart sound detection device 10 is mounted, the soft sheet 80 adheres tightly to the skin 11, so that the heart sound detection device 10
Is prevented from being displaced. FIG. 3 is a view for explaining that the heart sound detected by the heart sound detecting device 82 decreases due to the formation of an air layer in the conventional heart sound detecting device 82 in which the soft sheet 77 is not mounted. This shows a state in which the heart sound detection device 82 is attached to a predetermined heart sound detection site on the skin 11 of the living body. In FIG. 3, the body hair 78 on the skin 11 causes the contact surface 84 of the heart sound detection device 82 with the skin to contact the skin 11.
An air space 86 is formed between the two. In this state, a part of the heart sound wave 88 is reflected as a reflected wave 90 when traveling from the skin 11 to the air layer 86 and when traveling from the air layer 86 to the heart sound detecting device 82, and thus is detected by the heart sound detecting device 82. Heart sound 88 decreases. As described above, according to the present embodiment, the skin 1
1 is provided between the flexible resin film 36 and the skin 11 to reduce the discomfort when the heart sound detection device 10 is worn. The body hair 78 on the surface of the skin 11 with which the flexible resin film 36 contacts is covered with the soft sheet 77 without any gap, that is, since there is no air layer between the flexible resin film 36 and the skin 11, The sound wave 88 is no longer reflected at the boundary surface, and the density of the soft sheet 77 is closer to the density of the skin 11 than the density of air, and the speed of sound in the soft sheet 77 is higher than the speed of sound in air. Since the specific acoustic resistance R of the wearing sheet is closer to the specific acoustic resistance R of the skin 11 than the specific acoustic resistance R of the air, that is, the specific acoustic resistance R of air, the boundary between the skin 11 and the soft sheet 77 Reflection of heart sounds on the surface Since relatively small, reduction of heart sounds due to biological hairy is detected heart sound detector 10 can be suitably prevented. According to the present embodiment, the soft sheet 77
Has substantially the same density as the skin 11, the specific acoustic resistance R of the soft sheet 77 approaches the specific acoustic resistance R of the skin 11.
Since the reflection of the heart sound at the boundary surface with the body is further reduced, the reduction of the heart sound detected by the heart sound detection device 10 due to the fact that the living body is hairy is more suitably prevented. According to the present embodiment, the soft sheet 77
Is affixed to the contact surface of the flexible resin film 36 with the skin 11, so that it is not necessary to interpose the soft sheet 77 between the flexible resin film 36 and the skin 11 for each measurement. . According to this embodiment, the flexible resin film 3
Soft sheet 7 to be adhered to the contact surface of skin 6 with skin 11
7, an annular flexible sheet 80 is attached to the lower housing 14.
Since it is interposed between the bottom 18 and the skin 11, the feeling of discomfort when the heart sound detection device 10 is worn is further reduced. While the embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments. For example, in the above-described embodiment, the soft sheets 77 and 80 are previously attached to the flexible resin film 36 or the bottom portion 18 of the lower housing 14 as a part of the heart sound detecting device 10. Apart from the device 10, a mounting sheet made of the same material as the soft sheets 77 and 80 may be interposed between the heart sound detection device 10 and the skin 11. In the above embodiment, the microphone 4
For 0, a capacitive microphone was used,
It may be a piezoelectric microphone or a moving coil microphone. In addition, the present invention can be variously modified without departing from the gist thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a heart sound detecting device 10 according to one embodiment of the present invention. FIG. 2 is a sectional view of the heart sound detection device 10 of the embodiment of FIG. FIG. 3 is a diagram illustrating a state where a part of a heart sound wave from inside a living body is reflected by an air layer. [Description of Symbols] 10: Heart sound detection device 11: Skin 12: Upper housing 14: Lower housing 36: Flexible resin film 40: Microphones 76, 80: Soft sheets (sheets for mounting)

Claims (1)

Claims: 1. A housing having an opening in a bottom portion, the opening side of which is brought into close contact with the skin of a living body, a relatively hard flexible film for closing the opening, and a housing provided in the housing. A living body sound detecting device including a microphone that converts the vibration of the diaphragm into an electric signal and mounted on the skin of the living body, and a mounting device for the body sound detecting device interposed between the living body skin and the living body. A sheet, interposed between the flexible membrane and the skin of the living body,
A mounting sheet for the body sound detection device, which has substantially the same hardness as the skin of the living body.