Electronic stethoscope

Abstract

To provide an electronic stethoscope which attains a high SN ratio and has high accuracy of stethoscopy.SOLUTION: The electronic stethoscope comprises: a casing 92b; audible range sensors Xv2, Xv4, and Xw1 which are housed inside a housing cavity of the casing 92b, have a mechanical resonance frequency in an audible range, and have a drum-shape detection part for detecting a characteristic audible range signal; and a signal processing circuit 97 which is disposed inside the housing cavity to process signals output from the audible range sensors Xv2, Xv4, and Xw1.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention relates to an electronic stethoscope that selectively detects characteristic audible signals such as audible signals from a living body (hereinafter referred to as "biological audible signals").

Background Art

[0002] In 1816, R.T. Laennec, who was resistant to putting his ear directly on the chest of a young woman, rolled up a piece of paper to auscultate, which is regarded as the world's first stethoscope. Subsequently, in 1828, P.A. Piorry improved the sound collecting part to a trumpet shape. In 1894, a diaphragm-type acoustic stethoscope was invented, and in the 1940s, a bell-type acoustic stethoscope was invented. Non-Patent Document 1 also reports the difference in transmission characteristics between the diaphragm type and the bell type.

[0003] Thus, although the characteristics of acoustic stethoscopes have been studied and improved over time, the auscultation accuracy of acoustic stethoscopes tends to depend on the skills of medical staff, and there is still a problem with objectivity. The S.A. Levine heart murmur intensity classification published in 1933 and currently adopted by current medical recipients has six classifications. The first classification is a sound that cannot be heard by beginners, and the second classification is a sound that can be heard as a murmur when listened to carefully. One of the reasons for the increasing trend among young doctors to neglect auscultation, which is a basic part of clinical practice, including medical history taking, visual examination, and auscultation, is said to be the difficulty of hearing small heart sounds.

[0004] On the one hand, since around 1976, various electronic stethoscopes have been proposed and developed (see Patent Document 1). Some of the developed electronic stethoscopes are commercially available. Generally, an electronic stethoscope is designed to selectively detect a characteristic audible range signal in a main diagnostic band of about 20 Hz to 710 Hz that emerges from a diagnostic object (living body) as shown in FIG. 12. However, the audible range electroacoustic transducer used in conventional electronic stethoscopes emphasizes the linearity of frequency characteristics and has a mechanical resonance frequency outside the main diagnostic band, so the high reception sensitivity has been sacrificed. Due to the low reception sensitivity, problems arise such as signal distortion and noise generation that hinder clinicians from evaluating patients, and sensitivity limitations related to the amplification and reproduction of specific biological sounds of interest. For this reason, conventional electronic stethoscopes are not fully accepted by physicians and other medical professionals.

[0005] In the main diagnostic band of about 20 Hz to 710 Hz, the detected audible range signal includes both a characteristic audible range signal indicating physiological parameters such as breathing sounds indicating the respiratory rate and heart sounds, and environmental noise (ambient noise) from one or more noise sources. For example, environmental noise includes noise from external noise sources such as computers, medical devices, motors, pumps, fans, alarm devices, other electronic circuits, noise from other people such as visiting family members and medical staff near the patient, and noise from vehicles and helicopters. Depending on the situation, environmental noise includes environmental noise from patients that does not indicate the measured physiological parameters. Environmental noise from patients includes the patient's conversation and cough, etc. As a result, the electronic stethoscope generates all the detected audible range signals.

[0006] In an electronic stethoscope, the signal-to-noise ratio (SN ratio) generally decreases due to the presence of environmental noise regardless of the noise source. Depending on the situation, a decrease in the SN ratio may make it difficult to distinguish the physiological sound component of the signal from the noise component and provide an accurate measurement value. This problem is caused by the low reception sensitivity of the audible-range electroacoustic transducer used in conventional electronic stethoscopes because its mechanical resonance frequency is outside the main diagnostic band. In particular, it deteriorates in some emergency environments such as a flying helicopter or an ambulance, in which case the noise detected by the electronic stethoscope may be much larger than the target characteristic audible-range signal.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In view of the above problems, an object of the present invention is to provide an electronic stethoscope that achieves a high signal-to-noise ratio (SN ratio) in a wide frequency range of the audible range including the main diagnostic band even in an environment where the characteristic audible-range signal serving as the sound source is weaker than the noise level, and has high objectivity and auscultation accuracy.

Means for Solving the Problems

[0010] To achieve the above object, a first aspect of the present invention is an electronic stethoscope comprising: (a) a housing; (b) an audible range sensor housed inside a storage cavity of the housing, having a mechanical resonance frequency in the audible range and having a drum-shaped detection unit for detecting a characteristic audible range signal; and (c) a signal processing circuit disposed inside the storage cavity for signal-processing a signal output from the audible range sensor. Further, a second aspect of the present invention is an electronic stethoscope comprising: (p) a housing; (q) a plurality of audible range sensors housed inside a storage cavity of the housing and having different sizes from each other; and (r) a signal processing circuit disposed inside the storage cavity for signal-processing each of the signals output from the plurality of audible range sensors. In the electronic stethoscope according to the second aspect, each of the plurality of audible range sensors has a drum-shaped detection unit having a mechanical resonance frequency in the audible range.

Advantages of the Invention

[0011] According to the present invention, even in an environment where a characteristic audible range signal serving as a sound source is weaker than the noise level, a high SN ratio can be achieved in a wide frequency range of the audible range including a main diagnostic band, and an electronic stethoscope with high objectivity and auscultation accuracy can be provided.

Brief Description of the Drawings

[0012]

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Best Mode for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, the first to fourth embodiments of the present invention will be described to exemplify the present invention. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the sizes of the respective members, etc. are different from the actual ones. Therefore, specific thicknesses, dimensions, sizes, etc. should be determined more diversely in consideration of the gist of the technical idea that can be understood from the following description. Of course, there are also parts where the dimensional relationships and ratios are different between the drawings.

[0014] In the electronic stethoscope of this specification, an audible range sensor (audible range electroacoustic transducer) with a built-in amplification element is used. The "first main electrode region" of the insulated gate semiconductor element that constitutes the amplification element integrated and built into this audible range sensor with a built-in amplification element means a semiconductor region that becomes either the source region or the drain region in a field effect transistor (FET), a static induction transistor (SIT), or a new transistor structure equivalent to these. In an insulated gate bipolar transistor (IGBT) or a semiconductor element with a new structure equivalent to IGBT, it means a semiconductor region that becomes either the emitter region or the collector region. Also, in an insulated gate thyristor such as a MIS control static induction thyristor (SI thyristor) or a semiconductor element with a new structure equivalent to an insulated gate thyristor, it means a semiconductor region that becomes either the anode region or the cathode region. The "second main electrode region" means a semiconductor region that becomes either the source region or the drain region that does not become the first main electrode region in an FET, SIT, etc. In an IGBT, etc., it means a region that becomes either the emitter region or the collector region that does not become the first main electrode region. In a MIS control SI thyristor, etc., it means a semiconductor region that becomes either the anode region or the cathode region that does not become the first main electrode region.

[0015] Thus, if the "first main electrode region" is the source region, the "second main electrode region" means the drain region, and the "main current" flows between the first main electrode region and the second main electrode region. If the "first main electrode region" is the emitter region, the "second main electrode region" means the collector region. If the "first main electrode region" is the anode region, the "second main electrode region" means the cathode region. When the bias relationship is exchanged, in the case of a MISFET or the like, the functions of the "first main electrode region" and the "second main electrode region" may be exchangeable. Further, when simply described as the "main electrode region" in this specification, it is a comprehensive expression meaning either the first main electrode region or the second main electrode region that is technically appropriate.

[0016] Also, the terms "upper" and "lower" that define the "upper electrode" and "lower electrode" in the following description, or the terms "up" and "down", and further the terms such as "right" and "left", as well as the definition of the direction using the terms "up" and "down" are merely definitions for convenience of explanation and do not limit the technical idea of the present invention. For example, if the object is rotated by 90° and observed, up and down are read as left and right, and if it is rotated by 180° and observed, up and down are read in reverse. Further, in the following description, the case where the first conductivity type is p-type and the second conductivity type is n-type will be exemplarily described. However, the conductivity types may be selected in the reverse relationship, with the first conductivity type being n-type and the second conductivity type being p-type. Also, the "+" and "-" attached to "n" and "p" mean semiconductor regions with relatively higher or lower impurity densities compared to the semiconductor regions without the attached "+" and "-", respectively. However, even for semiconductor regions with the same attached "+" and "-" or semiconductor regions without the attached "+" and "-", it does not mean that the impurity densities of the respective semiconductor regions are exactly the same.

[0017] Furthermore, the first to fourth embodiments described below exemplify a method for embodying the technical idea of the present invention and devices used in the method, etc. The technical idea of the present invention does not specify the material, shape, structure, arrangement, etc. of the components, the procedure of the method, etc. as the following. The technical idea of the present invention is not limited to the content described in the first to fourth embodiments, and various modifications can be made within the technical scope defined by the invention specifying matters of the claims described in the claims.

[0018] (First Embodiment) The electronic stethoscope according to the first embodiment of the present invention includes a sound collecting unit (chest piece) 9a, a sound pipe 7, and an outer ear mounting unit (ear tip) 6, as shown in FIG. 1A. Although two outer ear mounting units 6 are shown in FIG. 1A, the number of outer ear mounting units 6 may be one. As shown in FIGS. 2 and 3A, etc., the sound collecting unit 9a is a built-in amplification element type audible range sensor (audible range electroacoustic transducer) X which is an individual element v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X w4 and X w5 can be incorporated. The audible range sensors X v1 ~X v4 and X w1 ~X w5 can be configured as semiconductor elements having an amplification function of directly inputting and amplifying a characteristic audible range signal indicating the characteristics of the object to be diagnosed to the gate electrode.

[0019] Each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 has a drum-shaped detection part, and as shown in FIGS. 8, 10A, 10B, 11A, etc. to be described later, since it has a mechanical resonance frequency in the audible range, the reception sensitivity of the characteristic audible range signal is high. The audible range sensors X shown by the large hexagon in FIG. 2 v1 ~X v4 and the audible range sensors X shown by the small hexagon w1 ~Xw5 The inner hexagons contained within each of the respective regions indicate the planar pattern of the vibration cavities that define the drum-shaped detection units. By setting the mechanical resonance frequency of the drum-shaped detection units to be within the audible range, for example, in the main diagnostic band of approximately 20 Hz to approximately 710 Hz contained within the audible range as shown in FIG. 12, high reception sensitivity can be achieved. In particular, for the audible range sensors X v1 ~X v4 and X w1 ~X w5 when an insulated gate semiconductor element such as a MOS transistor that amplifies the characteristic audible range signal is integrated in an integrated structure, the detected voltage signal can be directly amplified by a function similar to that of the insulated gate semiconductor element, achieving very high reception sensitivity.

[0020] The sound collecting unit 9a can be arranged in contact with or in proximity to the biological sample to be examined, such as the patient's chest, abdomen, crotch of the arm or leg, or any other arbitrary body part of the patient. The audible range sensors X v1 ~X v4 and X w1 ~X w5 can perform a function similar to that of an insulated gate semiconductor element that amplifies the characteristic audible range signal related to one or more biological processes occurring in the patient. For example, the audible range sensors X v1 ~X v4 and X w1 ~X w5 can amplify various characteristic audible range signals caused by the patient's heartbeat, respiration, blood flow, digestion, etc. as illustrated in FIG. 12.

[0021] Audible range sensors X v1 ~X v4 and audible range sensors X w1 ~X w5The feature audible range signal detected / amplified by [description of detection / amplification means] is subjected to signal processing (digital processing) by the signal processing circuit 97 shown in FIG. 3A etc., and its frequency characteristics are smoothed. The feature audible range signal with smoothed frequency characteristics can be led to the outer ear mounting part 6 through the speaker structure provided inside the acoustic tube 7 shown in FIG. 1B after D / A conversion. The acoustic tube 7 can include a hollow tube. The hollow tube may be filled with air. The acoustic tube 7 may be flexible. FIG. 1B shows the Y-shaped tube 702 of the electronic stethoscope including the speaker structure. The Y-shaped tube 702 is preferably a modular Y-shaped tube. In FIG. 1B, a single speaker 703 is placed inside the Y-shaped tube 702 at a suitable location such that the sound generated by the speaker 703 is transmitted through both the ear tubes 701a and 701b.

[0022] Since the location of the speaker structure within the electronic stethoscope should be selected so as to reduce or minimize the transmission of frictional noise in the acoustic tube 7, the speaker 703 may be incorporated into the outer ear mounting part 6 of the headset. The conductor 704 connected to the speaker 703 extends from the coupler of the acoustic tube 7 to the signal processing circuit 97 of the sound collecting part 9a through the lumen of the main tube of the acoustic tube 7.

[0023] Although not shown in FIG. 3A, the sound collecting part 9a of the electronic stethoscope according to the first embodiment can incorporate a communication circuit that transmits the information signal-processed by the signal processing circuit 97 to various information systems 3. By providing the communication circuit, as illustrated in FIG. 1A, the information signal-processed by the signal processing circuit 97 can be transmitted to the information system 3 in real time for easy visualization, and the heart rate and heart rate waveform can be displayed on the display of the information system 3. Furthermore, it can be stored in databases of various institutions such as hospitals, clinics, or databases or cloud-based health systems related to hospital or clinic networks. That is, as information received by the information system 3 in real time, functions of the information system 3 enable recording, display, slow-mode playback, storage, and further transmission to other information systems of feature audible range signals such as bio-audible range signals.

[0024] For the communication between the sound collection unit 9a and the information system 3, for example, wireless communication using electromagnetic waves in the 2.4 GHz band can be adopted. Electromagnetic waves in the 2.4 GHz band with an antenna power of 10 mW or less are defined as a "2.4 GHz band high-performance low-power data communication system" that does not require a license for a radio station in Article 38-2-2, Paragraph 1, Item 1 of the Radio Law. Therefore, it is a convenient frequency band for use in hospitals and within hospitals. Alternatively, the 5th generation mobile communication system (5G communication) defined by the International Telecommunication Union (ITU) may be used. Note that 5G communication is an example, and it goes without saying that 6G communication or 7G communication may also be used.

[0025] The information signal-processed by the signal processing circuit 97 can be accessed by the information system 3 of an organization interested in various biological information caused by the patient's heartbeat, respiration, blood flow, digestion, etc. via the communication circuit built into the sound collection unit 9a. For example, by installing AI in the information system 3 and having the AI perform machine learning on the information acquired by the electronic stethoscope according to the first embodiment, a highly objective auscultation can be achieved. On the side surface of the housing of the sound collection unit 9a, a display / operation unit 5 is provided, and it is connected to the acoustic tube 7 via the display / operation unit 5. The on / off of the power circuit, the adjustment of the sensitivity adjustment resistor R aij , the adjustment of the gain of the amplifier, the control of the communication circuit, the adjustment of the volume, the switching of the mode, and the display of the signal-processed information, etc. are performed by the display / operation unit 5.

[0026] The audible range sensors X v1 ~X v4 and X w1 ~X w5 The reception sensitivities of are, as shown by the difference between the solid line and the dashed-dotted line curves in FIG. 8, dependent on dimensions such as the inner diameter and diagonal diameter occupied by the audible range sensors. As shown in FIG. 2, the sound collection unit 9a of the electronic stethoscope according to the first embodiment includes a hexagonal drum-shaped detection unit with a first diagonal diameter at the center of the element array unit of the sound collection unit 9a in which nine hexagons are arranged, and arranges the first audible range sensor X w1 . An example of the detailed structure of the planar pattern of the first audible range sensor X w1 is shown in FIG. 4. And the first audible range sensor Xw1 Around it, second audible range sensors X each having a second diagonal diameter longer than the first diagonal diameter v1 , a third audible range sensor X v2 , a fourth audible range sensor X v3 and a fifth audible range sensor X v4 are arranged. The planar pattern of the second audible range sensor X v1 , the third audible range sensor X v2 , the fourth audible range sensor X v3 and the fifth audible range sensor X v4 is also a pattern including a hexagonal drum-shaped detection part on the inside, as shown in FIG. 2.

[0027] Furthermore, a sixth audible range sensor X having a first diagonal diameter shorter than the second diagonal diameter is arranged between the fifth audible range sensor X v4 and the second audible range sensor X v1 . Similarly, a seventh audible range sensor X having a first diagonal diameter is arranged between the second audible range sensor X w2 and the third audible range sensor X v1 , a eighth audible range sensor X having a first diagonal diameter is arranged between the third audible range sensor X v2 and the fourth audible range sensor X w3 . And furthermore, a ninth audible range sensor X having a first diagonal diameter is arranged between the fourth audible range sensor X v2 and the fifth audible range sensor X v3 . The planar pattern of the sixth audible range sensor X w4 , the seventh audible range sensor X v3 , the eighth audible range sensor X v4 and the ninth audible range sensor X w5 is also a pattern including a hexagonal drum-shaped detection part on the inside, as shown in FIG. 4. w2 , the seventh audible range sensor X w3 , the eighth audible range sensor X w4 and the ninth audible range sensor X w5 is also a pattern including a hexagonal drum-shaped detection part on the inside, as shown in FIG. 4.

[0028] As shown in FIG. 2 as the inner hexagon of the double hexagonal pattern, the housing 92a of the stethoscope according to the first embodiment arranges a plurality of drum-shaped detection parts with different diagonal diameters. The diagonal diameter of the first audible range sensor X having a drum-shaped detection part located at the center of the housing 92a w1 is that of the first audible range sensor Xw1 are arranged around w1 , and the second to fifth audible range sensors X each having a drum-shaped detection part v1 ~X v4 is smaller than the diagonal diameter of v4 . The audible range sensor X having a drum-shaped detection part with a large diagonal diameter shown by the hidden line inside FIG. 2 v1 ~X v4 and the audible range sensor X having a drum-shaped detection part with a small diagonal diameter w1 ~X w5 In the array of w5 , as can be seen from FIG. 8 and the like, the mechanical resonance frequencies are different from each other. Therefore, by intentionally shifting the respective mechanical resonance frequencies in the array composed of a plurality of drum-shaped detection parts from each other, the frequency band of the electronic stethoscope according to the first embodiment can be expanded so that the overall reception sensitivity is increased.

[0029] FIGS. 3A and 3B are cross-sectional views seen from the IIIA-IIIA direction of FIG. 2. In the electronic stethoscope according to the first embodiment, the fifth audible range sensor X w1 is arranged on the left side of the central first audible range sensor X v4 and the third audible range sensor X v2 is arranged on the right side, showing a structure. The first audible range sensor X w1 , the fifth audible range sensor X v4 and the third audible range sensor X v2 For example, as shown in FIG. 5 and the like, the detailed cross-sectional structure of v2 includes a vibration cavity 28 that constitutes a drum-shaped detection part. In FIGS. 3A and 3B, the blank part shown by a quadrangle inside the hatching of the central first audible range sensor X w1 schematically shows the vibration cavity corresponding to the inner hexagon located inside the small hexagonal region showing the first audible range sensor X w1 in FIG. 2. The blank part shown by a quadrangle inside the hatching of the fifth audible range sensor X v4 and the third audible range sensor X v2 is the fifth audible range sensor X in FIG. 2 v4 and the third audible range sensor X v2Inside the large hexagonal region shown, vibration cavities corresponding to the inner hexagons located respectively are schematically shown. However, this is a schematic representation, and the aspect ratio of the actual vibration cavity is different from that of the white square shown with exaggerated height in FIGS. 3A and 3B. For example, it is a flat square with a width of about 1.2 to 2.4 mm and a height of about 2 μm, and the aspect ratio is such that the height is hardly visible.

[0030] As shown in FIG. 3A, the sound collecting part 9a of the electronic stethoscope according to the first embodiment has a housing 92a. The housing 92a is surrounded by an outer skin having a flat plate-like part at least in part, and an audible range sensor X v1 ~X v4 and X w1 ~X w5 etc. are stored to form a storage cavity. The shape of the housing 92a shown in FIG. 3A is almost cylindrical except for the lower flange part. Therefore, as the main part, the curved surface that becomes the side surface of the cylinder, the flat surface that becomes the upper surface (ceiling surface) of the cylinder, and the flat surface that becomes the lower surface (bottom surface) of the cylinder respectively form the outer skin. In the housing 92a shown in FIG. 3A, the flat plate-like parts are the upper surface and the lower surface of the cylinder.

[0031] There is a step similar to that of a conventional acoustic stethoscope on the lower surface of the housing 92a, but the central part of the lower surface is flat. In the electronic stethoscope according to the first embodiment, a "signal input surface" where characteristic audible range signals are input is defined in a flat region of a part of the lower surface. And a recess provided on the lower surface inside the housing 92a at a position facing the signal input surface is selected as the sensor fixing part, and the first audible range sensor X w1 , the third audible range sensor X v2 and the fifth audible range sensor X v4 are respectively housed and fixed with the lower parts of their side surfaces on the inner wall of the sensor fixing part. Conversely, one surface (bottom surface) of the plate-like outer skin of the housing 92a facing the sensor fixing part is the signal input surface. Further, inside the storage cavity formed by the housing 92a, a power supply circuit 96 and a signal processing circuit 97 are built in. The power supply circuit 96 supplies power to 9 audible range sensors X v1 ~X v4 and X w1~X w5 It also supplies the necessary electrical energy to the signal processing circuit 97.

[0032] The signal processing circuit 97 is a sensor for detecting an audible range X v1 ~X v4 and X w1 ~X w5 The signal processing circuit 97 receives a signal from the audible sensor X and performs signal processing. v1 ~X v4 and X w1 ~X w5 Amplifiers 81 provided individually corresponding to each of the ij (i=v, w; j=1 to 4 or 5) and each amplifier 81 ij The audible range sensor X processes the signal by inputting the output from v1 ~X v4 and X w1 ~X w5 The main processing circuit 82 is common to the audible range sensor X v1 ~X v4 and X w1 ~X w5 The output from each of the amplifiers is connected to the amplifier 81 as a preamplifier. ij After A / D conversion, the audible range sensor X with different sizes v1 ~X v4 and audible range sensor X w1 ~X w5 The output signal from the main processing circuit 82 is smoothed in frequency response using digital technology. The main processing circuit 82 further processes the signal by removing noise signals, etc., and outputs the signal as a pure characteristic audible range signal.

[0033] The nine audible range sensors X shown in Figure 2 v1 ~X v4 and X w1 ~X w5By housing it in the sensor fixing part and detecting and amplifying the characteristic audible range signal indicating the characteristics of the object to be diagnosed, even if the diameter of the housing 92a is short, the characteristic audible range signal can be detected with sufficient signal strength. The maximum diameters of many currently sold sound collecting parts (chest pieces) are generally unified within 45 mm to 50 mm, and about 37 mm to 40 mm for pediatric use. However, the audible range sensors X v1 ~X v4 and X w1 ~X w5 By reducing the number to less than 9 shown in FIG. 2, even if the outer diameter of the sound collecting part 9a is miniaturized to an unprecedented size, auscultation can be performed well.

[0034] The material of the housing 92a is not particularly limited, and examples thereof include soft plastics such as polyvinyl chloride (PVC). Alternatively, a hard resin or a metal such as aluminum (Al) or titanium (Ti) may be used. To enhance the adhesion to the surface of the object to be diagnosed, an elastic material such as silicone rubber is desirable as the material of the housing 92a. Note that the shape of the housing 92a shown in FIG. 3A and the like is an example and is not limited to a cylindrical shape. The housing 92a may be surrounded by an outer skin having a flat plate-like portion at least partially, and a storage cavity may be formed inside the outer skin. Therefore, other three-dimensional shapes such as a semi-sphere may be used. In the case of a semi-sphere, the semi-spherical surface is continuous with the flat surface serving as the lower surface (bottom surface) of the semi-sphere so as to form a storage cavity. In the case of the outer skin of a semi-sphere, the flat plate-like portion is only the lower surface. Therefore, a "signal input surface" can be defined where the characteristic audible range signal is input to a part of the lower surface of the semi-sphere. The semi-spherical surface continuous with the flat surface serving as the lower surface does not have to be a surface with a uniform curvature and may include uneven portions.

[0035] In the sound collection unit 9a of the electronic stethoscope according to the first embodiment shown in FIG. 3A, a buffer film 93 having flexibility and elasticity is provided on the lower surface side of the housing 92a. In order to exhibit the flexibility and elasticity of the buffer film 93 that functions as a diaphragm on the lower surface of the housing, a buffer film holding portion 91 that holds the end portion (peripheral portion) of the buffer film 93 while maintaining flexibility and airtightness is provided at the bottom of the outer peripheral side surface of the housing 92a. Then, the buffer film (housing diaphragm) 93 is disposed so as to close the signal input surface on the bottom surface of the housing 92a. Similar to a conventional acoustic stethoscope, the buffer film 93 constitutes an air layer sealed to a desired volume between the signal input surfaces of the housing 92a.

[0036] By constituting the sealed air layer, the buffer film 93 functions as a diaphragm of the air layer, similar to an acoustic stethoscope. That is, when the electronic stethoscope according to the first embodiment is in use, as shown in FIG. 3A, when the buffer film 93 contacts the surface of the object to be diagnosed 1, the characteristic audible range signal is transmitted to the signal input surface using the air layer as a signal transmission medium. The characteristic audible range signal transmitted to the signal input surface passes through the signal input surface and reaches the audible range sensors X v1 ~X v4 and X w1 ~X w5 and causes the upper electrodes of each of them to vibrate as part of the components of the drum-shaped detection unit. Examples of the detailed cross-sectional structures of the audible range sensors X v1 ~X v4 and X w1 ~X w5 each include the upper electrode 25c as one layer included in the multilayer film that constitutes the drumhead (diaphragm) of the drum, as shown in FIG. 5 and the like.

[0037] Furthermore, a convex portion is provided on the lower surface of the housing 92a so as to surround the region of the signal input surface on the bottom surface of the housing 92a. When performing auscultation by strongly pressing the sound collection unit 9a against the surface of the object to be diagnosed 1 in the direction of the arrow shown in FIG. 3A until an indentation remains, the periphery of the buffer membrane (housing vibration membrane) 93 bends and the central portion of the buffer membrane 93 approaches the signal input surface. When the buffer membrane 93 contacts the convex portion, an air layer with a smaller volume than when lightly pressed is maintained between the buffer membrane (housing vibration membrane) 93 and the signal input surface, so that, similar to an acoustic stethoscope, it is possible to prevent the sensitivity of the electronic stethoscope according to the first embodiment from decreasing.

[0038] That is, when auscultating the characteristic audible range signal in FIG. 3A, the sound collection unit 9a is in contact with the surface of the object to be diagnosed 1, and an air layer with a smaller volume than when lightly pressed as shown in FIG. 3B is formed between the signal input surface of the housing 92a and the buffer membrane (housing vibration membrane) 93. The sound pressure in the air layer is determined by the ratio of the volume of the air layer to the amplitude of the surface of the object to be diagnosed 1 with which the buffer membrane 93 is in contact. The amplitude of the characteristic audible range signal on the surface of the object to be diagnosed 1 is about 0.3 μm during breathing. Assuming that the height of the air layer per unit area of the signal input surface of the housing 92a is 3 mm, the sound pressure due to the characteristic audible range signal indicating the characteristics of the object to be diagnosed is 10 Pa. By restricting the volume of the air layer, it is possible to acquire the characteristic audible range signal with high sensitivity without distorting it.

[0039] FIG. 3B shows the situation when the sound collection unit 9a is lightly (softly) pressed against the surface of the object to be diagnosed 1. The buffer membrane 93 does not contact the convex portion, and an air layer is formed between the signal input surface on the bottom surface of the housing 92a and the buffer membrane (housing vibration membrane) 93. Even in the case shown in FIG. 3B, by providing the buffer membrane 93, the volume of the air layer can be restricted more than when the buffer membrane 93 is not provided. According to the electronic stethoscope according to the first embodiment, with the configuration of the sound collection unit 9a as shown in FIGS. 3A and 3B, it is possible to acquire biological sounds with high sensitivity without distorting them. The volume of the air layer affects the frequency characteristics of the electronic stethoscope according to the first embodiment.

[0040] The material of the buffer film 93 is not particularly limited, but it is preferably formed of an elastic material such as silicone rubber. The buffer film holding portion 91 and the buffer film 93 may be made of an integral silicone rubber and may be detachable from the housing 92a. Further, as in the examples shown in FIGS. 3A and 3B, the convex portion may be formed integrally with the bottom surface of the housing 92a, or may be formed integrally with the buffer film 93. Further, the convex portion is not limited to the case of the examples shown in FIGS. 3A and 3B. For example, the position, number, and shape may be appropriately adjusted so that the change in the volume of the air layer due to the bending of the surface region of the diagnostic object 1 or the buffer film (housing vibration film) 93 can be suppressed. In FIG. 2, the audible range sensors X v1 ~X v4 and X w1 ~X w5 are illustrated as an example where the planar pattern of and X v1 ~X v4 and X w1 ~X w5 becomes a hexagonal drum-shaped detection portion. However, the planar pattern of the audible range sensors X

[0041] is not limited to a hexagon, and various planar patterns of drum-shaped detection portions such as a rectangle and an octagon can be adopted. As will be described later with reference to FIGS. 5 and 7, etc., the audible range sensors X v1 ~X v4 and X w1 ~X w5 used as the audible range sensors in the electronic stethoscope according to the first embodiment can each separate the upper part of the common substrate 11 into channel formation regions 14 that are electrically independent of each other by the element isolation insulating film 13, and a configuration in which they are two-dimensionally arranged on one chip based on this channel formation region 14 is possible. However, each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 may be configured to be hybrid-mounted. In any case, the audible range sensors X v1 ~X v4 and X w1 ~X w5On each of the channel formation regions 14, as shown in FIGS. 5 and 7, etc., an oscillating cavity 28 is provided so as to have an integral structure as a part of the amplification element. When the channel formation region 14 is a p-type semiconductor region, the channel formation region 14 is a member having a structure and function corresponding to a p-well of a normal semiconductor integrated circuit. As shown in the cross-sectional view of FIG. 5, etc., on the surface of the channel formation region 14 of the first conductivity type, a first main electrode region 15b and a second main electrode region 15a of the second conductivity type are arranged, and an insulated gate type semiconductor element as an amplification element is configured as a part of the elements of the drum-shaped detection part.

[0042] Conventionally, in the technical concept of a capacitive MEMS (Micro-Electro-Mechanical System) element called a cMUT (Capacitive Micro-Machined Ultrasonic Transducer), the change in the charge induced in the capacitance between the upper electrode and the lower electrode has been detected. However, there is a limit to the improvement of the reception sensitivity in the method of the conventional drum-shaped (capacitive) acoustic element that detects the change in the charge accumulated in the capacitance between the upper electrode and the lower electrode. For this reason, the inventors of the present invention have deviated from the method of the conventional drum-shaped acoustic element that detects the change in the charge induced in the capacitance, and have integrated (integrated) an insulated gate type semiconductor element as the internal structure of a sensor with built-in amplification element in the audible range.

[0043] That is, by incorporating and integrating an insulated gate type semiconductor element into an audible range sensor, the change in capacitance due to the input of a characteristic audible range signal indicating the characteristics of the diagnostic object is focused on the charge induced on the surface of the channel formation region 14 by Gauss's theorem and the change in potential accompanying this charge. That is, the height of the surface potential of the channel formation region 14 is controlled by the charge induced on the surface of the channel formation region 14. A new semiconductor element in which the change in capacitance due to the input of the characteristic audible range signal controls the height of the potential barrier of the channel through which the current flows, and thereby detects the input of the characteristic audible range signal as a change in current, is used as the audible range sensor used in the stethoscope according to the first embodiment.

[0044] In the plan view of FIG. 4, the two rectangles represented by hidden lines are the audible range sensors X v1 ~X v4and X w1 ~X w5 The figure shows the first main electrode region 15b and the second main electrode region 15a of the insulated gate semiconductor device integrally included in each of ~X. The two rectangles facing each other are the hexagonal audible range sensor X that bites into the inside of the inner hexagon from the outer donut-shaped hexagon (hexagonal ring). v1 ~X v4 and X w1 ~X w5 In each of ~X and X, they are arranged. However, Fig. 4 is a schematic diagram, and the distance between the opposing portions of the first main electrode region 15b and the second main electrode region 15a is a length corresponding to the gate length of the insulated gate semiconductor device, and it is an exaggerated expression enlarged compared to the actual gate length. That is, while the diagonal length of the actual central lower electrode 17c is designed to be about 300 to 800 μm, the distance (gate length) between the opposing portions of the first main electrode region 15b and the second main electrode region 15a is about 1 μm. In the audible range sensor used in the electronic stethoscope according to the first embodiment, the change in the capacitance of the audible range sensor X is detected as a change in current by the current flowing between the first main electrode region 15b and the second main electrode region 15a. v1 ~X v4 and X w1 ~X w5 is detected as a change in current.

[0045] For each of the insulated gate semiconductor devices two-dimensionally arranged inside the recess of the sensor fixing portion, in order to extract a current signal from the first main electrode region 15b or the second main electrode region 15a, an output signal line R is connected to each audible range sensor. i In Fig. 4, an example is shown in which the output signal line R is connected to the first contact plug provided on the right side of each audible range sensor having a hexagonal drum-shaped detection portion. i is shown connected to the first contact plug provided on the right side of each audible range sensor having a hexagonal drum-shaped detection portion. In Figs. 4 and 6A, from the first main electrode region (source region) 15b of the insulated gate semiconductor device incorporated as a part of the structure of the audible range sensor, the source resistance R SSAlthough an example is given of extracting a current signal in the form of a source follower using it, it is not limited to the circuit topologies of FIGS. 4 and 6A. For example, as shown in FIG. 6C, the source region is grounded (as the second potential), and a drain resistor R is used to extract a current signal from the side of the second main electrode region (drain region) 15a. DD This configuration may also be used.

[0046] In FIG. 6A, the output of the output signal line R i is input to each of the amplifiers 81 v1 ~X v4 and X w1 ~X w5 individually provided corresponding to each of them, and the output of the amplifier 81 ij is input to the common main processing circuit 82 respectively. This is an example of extracting one audible range sensor. The audible range sensors X ij ~X v1 and the audible range sensors X v4 ~X w1 ~X w5 have different sizes (diagonal diameters) from each other, so as shown in FIG. 8, the frequency dependence characteristics of the reception sensitivity are different. The audible range sensors X v1 ~X v4 and X w1 ~X w5 The respective amplifiers 81 ij individually provided for each of them adjust the amplification factor so as to adjust the output levels of the audible range sensors X w1 ~X w5 having the first diagonal diameter and the audible range sensors X v1 ~X v4 and the audible range sensors X w1 ~X w5 having the first diagonal diameter.

[0047] Furthermore, as shown in FIG. 11A, by changing the value of the sensitivity adjustment resistor R aij it is possible to change the frequency dependence characteristics of the reception sensitivity of each of the audible range sensors X v1 ~X v4 and the audible range sensors X w1 ~X w5 Therefore, audible range sensors X having the same diagonal diameterv1 ~X v4 By changing the values of the respective sensitivity adjustment resistors R of aij ~X v1 ~X v4 it is possible to change the frequency dependence characteristics of the respective reception sensitivities of ~X. Similarly, by changing the values of the respective sensitivity adjustment resistors R of the audible range sensors X w1 ~X w5 it is possible to change the frequency dependence characteristics of the respective reception sensitivities of the audible range sensors X aij ~X w1 ~X w5

[0048] That is, all of the frequency dependence characteristics of the reception sensitivities of the nine audible range sensors X v1 , X v2 , X v3 , X v4 , X w1 , X w2 , X w3 , X wj , X w4 and X w5 can be set to be different from each other, and a wideband frequency dependence characteristic of the reception sensitivity can be realized as a whole. When all of the frequency dependence characteristics of the reception sensitivities of the nine audible range sensors X v1 , X v2 , X v3 , X v4 , X w1 , X w2 , X w3 , X wj , X w4 and X w5 are set to be different from each other, the amplification factors of the respective amplifiers 81 provided individually corresponding to each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 can be individually controlled to adjust the nine signal levels input to the common main processing circuit 82. ij

[0049] ​​On the one hand, as illustrated in FIGS. 10A and 10B, a DC bias voltage V as a first potential applied between the upper electrode 25c, which is a component of the drum-shaped detection unit, and the peripheral lower electrode 17o bias By changing the value of, the audible range sensor X v1 ~X v4 and the audible range sensor X w1 ~X w5 It is possible to change the resonance frequency and the frequency dependence characteristics of the reception sensitivity of each of. Therefore, by changing the value of the DC bias voltage V v1 ~X v4 for each of the audible range sensors X bias It is possible to change the resonance frequency and the frequency dependence characteristics of the reception sensitivity of each of the audible range sensors X v1 ~X v4 Similarly, by changing the value of the DC bias voltage V w1 ~X w5 for each of the audible range sensors X bias It is possible to change the resonance frequency and the frequency dependence characteristics of the reception sensitivity of each of the audible range sensors X w1 ~X w5

[0050] That is, by setting the value of the DC bias voltage V bias for the nine audible range sensors X shown in FIG. 2 v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X w4 and X w5 it is possible to set all of the frequency dependence characteristics of the reception sensitivity to be different from each other and to realize wide-band frequency dependence characteristics of the reception sensitivity as a whole. The value of the DC bias voltage V bias for the nine audible range sensors X v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X​w4 and X w5 Even when all of the frequency-dependent characteristics of the reception sensitivities of X v1 ~X v4 and X w1 ~X w5 Amplifiers 81 individually provided corresponding to each of X ij The amplification factor of each can be individually controlled to adjust the nine signal levels input to the common main processing circuit 82.

[0051] Furthermore, by individually controlling the value of the sensitivity adjustment resistor R aij and the value of the DC bias voltage V bias all of the mechanical resonance frequencies and the frequency-dependent characteristics of the reception sensitivities of the nine audible range sensors X v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X w4 and X w5 can be set to be different from each other, and a wideband resonance frequency and frequency-dependent characteristics of the reception sensitivity can be realized as a whole. The sensitivity adjustment resistor R aij value and the value of the DC bias voltage V bias both, for the nine audible range sensors X v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X w4 and X w5 Even when all of the resonance frequencies and the frequency-dependent characteristics of the reception sensitivities are set to be different from each other, the audible range sensors X v1 ~X v4 and X w1 ~X w5 Amplifiers 81 individually provided corresponding to each of X ij The amplification factor of each can be individually controlled to adjust the nine signal levels input to the common main processing circuit 82.

[0052] As shown in FIG. 5, each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 of the channel formation region 14, which is a component thereof, is provided as a part of each of the corresponding insulated gate semiconductor elements. That is, as shown in FIG. 5, the audible range sensors X v1 ~X v4 and X w1 ~X w5 each have a central lower electrode 17c that is a common region with the gate electrode of each of the corresponding insulated gate semiconductor elements. Thus, the insulated gate semiconductor elements are incorporated as a part of each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 To drive the integrated insulated gate semiconductor elements, a power supply wiring V DD is connected to the second main electrode region 15a of the insulated gate semiconductor element, as shown in FIG. 4. The power supply wiring V DD is shown connected to a second contact plug provided on the left side of each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 having a hexagonal drum-shaped detection portion in FIG. 4.

[0053] Hereinafter, each of the audible range sensors X v1 ~X v4 and X w1 ~X w5 will be comprehensively referred to as "audible range sensor X ij " (i = v, w: j = 1 to 4 or 5). As shown in FIG. 4, the audible range sensor X ijIt includes a peripheral lower electrode (fixed potential electrode) 17o in the shape of a perforated hexagon (hexagonal ring), and a hexagonal central lower electrode (floating electrode) 17c that is concentrically arranged at a distance from the peripheral lower electrode 17o inside the hexagonal opening provided in the center of the peripheral lower electrode 17o. The central lower electrode 17c is a flat electrode in an electrically floating state (floating state). The peripheral lower electrode 17o and the central lower electrode 17c constitute the lower electrodes (17c, 17o) of the audible range sensor X, which is a sensor with a built-in amplification element. ij However, the central lower electrode 17c is in an electrically floating state, and the peripheral lower electrode 17o is connected to the second potential (ground potential). In FIG. 4, a structure in which the peripheral lower electrode 17o and the central lower electrode 17c are divided into a concentric hexagonal shape is illustrated. However, the topology for dividing the lower electrodes (17c, 17o) into the peripheral lower electrode 17o and the central lower electrode 17c is not limited to the pattern illustrated in FIG. 4.

[0054] For example, the hexagon can be divided into two by a diagonal line passing through the center of the hexagon, and one of the two opposing parts can function as the peripheral lower electrode 17o and the other as the central lower electrode 17c. In this case, a topology can also be adopted in which a concave portion (cut pattern) is provided near the center of the side of the central lower electrode 17c facing the peripheral lower electrode 17o, and a protrusion provided near the center of the opposing side of the peripheral lower electrode 17o is inserted into this concave portion. Furthermore, the lower electrode can be divided into a large number of regions of three or more divisions, and each of the divided lower electrodes can be classified to function as either the peripheral lower electrode 17o or the central lower electrode 17c. The regions with the same function as the peripheral lower electrode 17o can be electrically connected to each other, and the regions with the same function as the central lower electrode 17c can be electrically connected to each other. Even when the lower electrode is divided into a large number of regions, the regions functioning as the peripheral lower electrode 17o are each connected to the second potential (ground potential), and the regions functioning as the central lower electrode 17c are set in an electrically floating state.

[0055] However, a topology in which the central lower electrode 17c and the peripheral lower electrode 17o are concentrically arranged is preferable in terms of sensitivity characteristics. Even when a divided pattern is used, a topology with two peripheral lower electrodes 17o that face each other in a hexagonal shape along the diagonal is preferable. Then, recesses are provided near the centers of the opposing sides of the opposing peripheral lower electrodes 17o, and the pattern of the opening is formed by the opposing recesses. A concentric topology may be used such that the central lower electrode 17c is inserted inside the pattern of this opening.

[0056] The audible range sensor X used in the electronic stethoscope according to the first embodiment ij In this case, the lower electrodes (17c, 17o) having the topology of the divided electrodes face the upper electrode 25c that is a component of the drum-shaped detection unit via the vibration cavity 28 as shown in FIG. 5. The planar pattern of the vibration cavity 28 defines the planar pattern of the drum-shaped detection unit. The electric field between the peripheral lower electrode 17o constituting the lower electrodes (17c, 17o) and the upper electrode 25c maintains the main voltage during reception of the audible range sensor X ij On the other hand, the first main electrode region 15b and the second main electrode region 15a shown by the hidden-line rectangles in FIG. 4 are provided with their short sides facing each other and spaced apart. The central lower electrode 17c constituting the lower electrodes (17c, 17o) functions to electrostatically control the potential of the channel region formed on the surface of the channel formation region 14 between the first main electrode region 15b and the second main electrode region 15a with the potential due to the charges induced in the central lower electrode 17c while maintaining a floating state.

[0057] As shown in FIG. 4, two rectangular recesses (cuts) are provided as a planar pattern on the outer periphery of the peripheral lower electrode 17o forming a hexagonal ring, and the first and second contact plugs are arranged in each of the two recesses. That is, the first contact plug 24b is arranged inside the recess provided on the right vertical side of the hexagonal planar pattern constituting the outer periphery of the peripheral lower electrode 17o, and the second contact plug 24a is arranged inside the recess provided on the left vertical side. Further, a third contact plug is arranged on the upper right slant side of the hexagon constituting the outer periphery of the peripheral lower electrode 17o.

[0058] As shown in FIG. 4, the first contact plug 24b is connected to the first main electrode region 15b for extracting a current signal from the first main electrode region 15b that constitutes an insulated gate semiconductor device functioning as the audible range sensor X. Although the case of extracting the current signal in the form of a source follower from the first main electrode region 15b (source region) 15b is illustrated, a configuration in which the source region is grounded and the current signal is extracted from the second main electrode region 15a (drain region) 15a side may also be adopted. The second contact plug 24a is connected to the second main electrode region 15a for supplying the power supply voltage V ij from the power supply wiring V DD to the second main electrode region 15a that constitutes an insulated gate semiconductor device functioning as the audible range sensor X DD . ij

[0059] As shown in FIG. 5, the audible range sensor used in the electronic stethoscope according to the first embodiment is composed of a semiconductor region of a first conductivity type (p-type), and includes a channel formation region 14 set to a second potential (= ground potential GND), and a first main electrode region 15b and a second main electrode region 15a of a second conductivity type (n-type) that are provided facing each other and spaced apart on the surface of the channel formation region 14. Further, the audible range sensor includes a gate insulating film (12, 16) provided on the first main electrode region 15b and the second main electrode region 15a, and on the channel formation region 14 sandwiched between the first main electrode region 15b and the second main electrode region 15a, and a central lower electrode 17c made of a conductor layer provided in an electrically floating state above the channel formation region 14 sandwiched between the first main electrode region 15b and the second main electrode region 15a and on the gate insulating film (12, 16), having the same function as an insulated gate semiconductor device. The central lower electrode 17c corresponds to the gate electrode of a normal insulated gate semiconductor device. As the conductor layer used for the central lower electrode 17c, a conductor material having a low specific resistance such as an impurity-added polycrystalline silicon (doped polysilicon: DOPOS) film can be adopted. The gate insulating film (12, 16) illustrates a two-layer structure of a first gate insulating film 12 on the lower layer side and a second gate insulating film 16 on the upper layer side, but is not limited to the structure shown in FIG. 5. ​

[0060] However, as shown in FIG. 5, a configuration in which a peripheral lower electrode 17o made of a conductor layer that is adjacent to and spaced apart from the central lower electrode 17c and is set to the second potential GND is further provided on the gate insulating films (12, 16) is a feature different from that of a normal insulated-gate semiconductor device. The same conductor material as that of the central lower electrode 17c, for example, a low-resistivity DOPOS film or the like, can be adopted for the peripheral lower electrode 17o. The central lower electrode 17c and the peripheral lower electrode 17o constitute a lower electrode (17c, 17o) having a split structure. That is, with respect to the lower electrode (17c, 17o) composed of the central lower electrode 17c and the peripheral lower electrode 17o, a cavity vibration film 23 made of an insulating film facing through a vibration cavity 28, and in contact with the upper surface of the cavity vibration film 23 and facing the central lower electrode 17c and the peripheral lower electrode 17o through the vibration cavity 28, a first potential V bias is set, and an upper electrode 25c that is a component of the drum-shaped detection unit is provided to constitute an audible-range sensor with a built-in amplification element.

[0061] A vibration cavity 28 is provided as a drum-shaped sealed space between the lower electrode (17c, 17o) and the upper electrode 25c. In FIG. 5, cavity formation insulating films 20 are arranged on the right side and the left side of the vibration cavity 28 so as to surround the vibration cavity 28. The cavity formation insulating film 20 that supports the periphery of the upper electrode 25c corresponds to the body that supports the drumhead (vibration film) of the drum, and the support rigidity of the cavity formation insulating film 20 is a factor that determines the mechanical resonance frequency of the drum-shaped detection unit. In the audible-range sensor with a built-in amplification element, the displacement of the upper electrode 25c, which is a component of the drum-shaped detection unit, due to a characteristic audible-range signal Φ indicating the characteristics of the diagnostic object can be detected as a change in the current flowing between the first main electrode region 15b and the second main electrode region 15a. In the vicinity of the center of the drum-shaped detection unit of the upper electrode 25c in FIG. 5, the white double-headed arrow shown superimposed on the upper electrode 25c means the displacement of the upper electrode 25c due to the characteristic audible-range signal Φ.

[0062] In addition to the upper electrode 25c, as shown in FIG. 5, a first surface wiring layer 25b and a second surface wiring layer 25a are provided at positions deviated from the vibration cavity 28 on the upper surface of the cavity vibration membrane 23. A first contact plug 24b that penetrates the cavity vibration membrane 23, the cavity forming insulating film 20, the second gate insulating film 16, and the first gate insulating film 12 is provided between the first surface wiring layer 25b and the first main electrode region 15b. Similarly, a second contact plug 24a that penetrates the cavity vibration membrane 23, the cavity forming insulating film 20, the second gate insulating film 16, and the first gate insulating film 12 is provided between the second surface wiring layer 25a and the second main electrode region 15a. That is, the upper end of the first contact plug 24b is metallurgically connected to the first surface wiring layer 25b, and the lower end of the first contact plug 24b is electrically connected to the first main electrode region 15b. Therefore, the first surface wiring layer 25b and the first main electrode region 15b are electrically connected by the first contact plug 24b.

[0063] Similarly, the upper end of the second contact plug 24a is metallurgically connected to the second surface wiring layer 25a, and the lower end of the second contact plug 24a is electrically connected to the second main electrode region 15a. Therefore, the second surface wiring layer 25a and the second main electrode region 15a are electrically connected by the second contact plug 24a. The first surface wiring layer 25b corresponds to the output signal line R shown in FIG. 4. i On the other hand, the second surface wiring layer 25a corresponds to the power supply line V shown in FIG. 4. DD On the cavity vibration membrane 23, an upper electrode protection film 26 such as a silicon oxide film is coated so as to cover the upper electrode 25c, the first surface wiring layer 25b, and the second surface wiring layer 25a, which are components of the drum-shaped detection unit. Further, a tip protection film 34 such as a polyimide film is laminated on the upper electrode protection film 26.

[0064] The cavity vibration film 23, the upper electrode 25c, the upper electrode protective film 26, and the tip protective film 34 constitute the "vibrating part (23, 25c, 26, 34)" of the drum-shaped detection part. The vibrating part (23, 25c, 26, 34) is a multilayer film corresponding to the drumhead (vibration film) of a drum. The size (diagonal diameter) of the vibrating part (23, 25c, 26, 34) defined by the planar pattern of the vibration cavity 28, the rigidity rate of each material, and the thickness of each material are one of the other factors that determine the mechanical resonance frequency of the drum-shaped detection part. The tip protective film 34 closes the liquid introduction hole 27 for introducing a removal liquid for selectively dissolving and removing the sacrificial layer by wet etching during the process of forming the vibration cavity 28. The liquid introduction hole 27 penetrates the upper electrode protective film 26 and the cavity vibration film 23 and reaches the vibration cavity 28 that defines the drum-shaped detection part. By closing the liquid introduction hole 27, the inside of the vibration cavity 28 is maintained in a reduced-pressure atmosphere of an inert gas.

[0065] In FIG. 5, the capacitance formed between the upper electrode 25c and the central lower electrode 17c near the center of the vibration cavity 28 that defines the planar pattern of the drum-shaped detection part is shown as C1. Since the capacitance value of the capacitance C1 changes depending on the displacement of the upper electrode 25c, it is a variable capacitance as shown in FIGS. 6A to 6C. The capacitance value of the capacitance C1 affects the value of the mechanical resonance frequency of the drum-shaped detection part determined by the size, rigidity rate, and thickness of the vibrating part (23, 25c, 26, 34), and further, the support rigidity of the cavity-forming insulating film 20. Therefore, the gap thickness on the back surface of the vibrating part (23, 25c, 26, 34) is a factor that affects the value of the mechanical resonance frequency of the drum-shaped detection part. Also, in FIG. 4, the peripheral lower electrode 17o that surrounds the periphery of the capacitance C1 in a hexagonal ring shape represents the inter-electrode capacitance formed between it and the upper electrode 25c as C2. The inter-electrode capacitance C2 is the inter-electrode capacitance formed between the peripheral lower electrode 17o at the ground potential (second potential) GND and the upper electrode 25c. Since the capacitance value of the capacitance C2 also changes depending on the displacement of the upper electrode 25c, it is a variable capacitance as shown in FIGS. 6A to 6C. The capacitance value of the capacitance C2 also affects the value of the mechanical resonance frequency of the drum-shaped detection part determined by the size, rigidity rate, and thickness of the vibrating part (23, 25c, 26, 34) and the support rigidity of the cavity-forming insulating film 20.

[0066] In order to distinguish between the two variable capacitances, they will be referred to as the "first variable capacitance C1" and the "second variable capacitance C2" hereinafter. The second variable capacitance C2 is a capacitance that has a role equivalent to that of a capacitance configured between an upper electrode and a lower electrode in a conventional capacitive element such as a cMUT. On the other hand, the first variable capacitance C1 is a capacitance for inducing charges that is necessary to drive an insulated gate semiconductor element that performs a function specific to the audible range sensor for the electronic stethoscope according to the first embodiment. Furthermore, in FIG. 5, a gate-source capacitance C gs However, a gate-drain capacitance C gd However, an insulating film capacitance C is formed between the central lower electrode 17c and the channel forming region 14. OX is shown.

[0067] In the equivalent circuit shown in FIG. 6A to FIG. 6C, the area X vj (X wj At the left edge of the paper, which is outside the bias and output resistance (internal resistance of the power supply) R O In FIG. 6A to FIG. 6C, the region X vj (X wj ) to the left edge of area X vj (X wj The horizontal line protruding from the line 100 is the DC bias supply line V bias In FIG. 6A and FIG. 6C, the DC bias supply line V bias and output resistance R O For the series circuit, the sensitivity adjustment resistor R aij A circuit is shown in which the DC bias supply line V bias The sensitivity adjustment resistor R aij This indicates that the device is grounded via

[0068] FIG. 6B shows a source follower format similar to that of FIG. 6A, but the central lower electrode 17c is connected to a sensitivity adjustment resistor R aij The equivalent circuit is shown when the resistor R is grounded. aijIf it is large enough, even if the central lower electrode 17c is grounded through the sensitivity adjustment resistor R aij , the central lower electrode 17c can function as a pseudo central lower electrode. And on the right side within the dashed region X vj (X wj ) in FIGS. 6A and 6C, a series circuit of a first variable capacitor C1 having one end grounded through a sensitivity adjustment resistor R aij and an n-channel MOSFET (hereinafter referred to as "nMOSFET") is shown. In FIG. 6B, the connection node of the insulation film capacitance C OX ≈C3 of the nMOSFET and the first variable capacitor C1 is shown as an equivalent circuit grounded through a sensitivity adjustment resistor R aij . The sensitivity adjustment resistors R aij shown in each of FIGS. 6A to 6C can be adjusted using the display / operation unit 5 of the sound collection unit 9a according to environmental noise and various physiological parameters as shown in FIG. 12 and the like.

[0069] However, the nMOSFETs in FIGS. 6A to 6C are merely examples, and various insulated gate semiconductor devices described at the beginning of the section [Embodiment for Carrying Out the Invention] can be adopted. In addition to the insulated gate semiconductor devices described at the beginning of the section [Embodiment for Carrying Out the Invention], other insulated gate semiconductor devices such as high electron mobility transistors (HEMTs) may also be used. In the equivalent circuits shown in FIGS. 6A to 6C, the DC bias supply line V bias of the first potential is connected in parallel with the series circuit of the first variable capacitor C1 and the nMOSFET and the second variable capacitor C2. Since FIGS. 6A and 6B are equivalent circuit diagrams when taking out the output in the source follower form, the source terminal of the nMOSFET is connected to the second potential (ground potential) through a source resistor R SS , and the current output from the source terminal is led to an amplifier 81 ij provided individually corresponding to the audible range sensor X ij .

[0070] That is, since the signal amplified by the integrated nMOSFET is led to an amplifier 81 ij provided individually corresponding to the audible range sensor X ij , the amplifier 81ij The signal level input to ij is very high. Therefore, amplifier 81 ij can achieve a large signal-to-noise ratio (SN ratio) as the input signal. Since the SN ratio of the input signal of amplifier 81 ij is high, the SN ratio of the output signal of amplifier 81 ij is also high, and signal processing for removing noise signals in the main processing circuit 82 after amplifier 81 ij can also be achieved at a high level. Therefore, even in an environment where the characteristic audible range signal serving as the sound source is weak and there is environmental noise, a pure characteristic audible range signal with a high SN ratio can be output from the main processing circuit 82 of the signal processing circuit 97.

[0071] In the equivalent circuit shown in FIG. 6C, the DC bias supply line V of the first potential bias is connected in series with the series circuit of the first variable capacitor C1 and the nMOSFET and in parallel with the second variable capacitor C2. Since FIG. 6C is an equivalent circuit diagram when taking out a current signal from the drain region side, the drain terminal of the nMOSFET is connected to the power supply V DD via the drain resistance R DD , and the current output from the drain terminal is led to the amplifier 81 ij individually provided corresponding to the audible range sensor X ij . In any of FIGS. 6A to 6C, the second variable capacitor C2 in which the potential of one electrode is set to the second potential V bias , the first variable capacitor C1 connected in parallel with the second variable capacitor C2, and the series circuit of the nMOSFET form the basic configuration.

[0072] As shown in FIG. 6D, in the insulated gate semiconductor element incorporated in the audible range sensor X ij of the electronic stethoscope according to the first embodiment, the central lower electrode 17c, which is one electrode of the first variable capacitor C1, corresponds to the control electrode (gate electrode) of a normal insulated gate semiconductor element. Usually, in an insulated gate semiconductor element such as an nMOSFET, there are a gate-source capacitance C gs , a gate-drain capacitance C gd , and an insulating film capacitance C OXis distributed. As a rough idea, assuming that the capacitance C3 = C around the central lower electrode 17c corresponding to the gate electrode, OX in the equivalent circuits of FIGS. 6A to 6C, it can be expressed using the capacitance C3. For the first variable capacitance C1 and the second variable capacitance C2, the capacitance C OX that can approximate the capacitance C3 whose value does not change even when the upper electrode 25c is displaced is a fixed capacitance. Therefore, hereafter, the capacitance C3 formed by the central lower electrode 17c will be referred to as the "fixed capacitance C3". For simplicity, it is assumed that the fixed capacitance C3 is the capacitance between the gate substrates shown in FIG. 6D.

[0073] First, consider how much voltage is applied across the fixed capacitance C3 in the series circuit of the first variable capacitance C1 and the fixed capacitance C3 shown in the equivalent circuits of FIGS. 6A to 6C. Let the charge induced in the first variable capacitance C1 be q1, the voltage across the first variable capacitance C1 be V1, the charge induced in the fixed capacitance C3 be q3, and the voltage across the fixed capacitance C3 be V3. In a series circuit, q1 = q3 = q. So, the voltage V bias across the series circuit of the first variable capacitance C1 and the fixed capacitance C3 is

Equation

[0074] In FIG. 5, let the area of the central lower electrode 17c be S1, the electrode distance between the upper electrode 25c forming the first variable capacitance C1 and the central lower electrode 17c be d, and the thickness t OX (= T OX1 + T OX2 ) of the gate insulating films (12, 16) forming the fixed capacitance C3. Also, let the permittivity of vacuum be ε0 and the relative permittivity of the silicon oxide film be ε r . Then, C1 = ε0S1 / d ………(2) C3 = ε0ε r S1 / t OX ………(3) Therefore, by capacitance division in the series circuit of the first variable capacitance C1 and the fixed capacitance C3, the voltage V3 generated across the fixed capacitance C3 is

Equation

[0075] For example, assuming d = 2 μm, t OX = 100 nm, and the relative permittivity ε of the silicon oxide film r = 4.0, from Equation (4), for the voltage V across both ends of the fixed capacitor C3, it can be seen that 1 / 81 of the DC bias voltage V bias is applied. However, since the area S1 of the central lower electrode 17c used in the audible range is larger than the area S AA of the active region of the insulated-gate semiconductor device (S AA ≪ S1), it is not necessary to make the entire area directly below the central lower electrode 17c the gate insulating film of the insulated-gate semiconductor device. The size S AA of the active region is defined by (gate length) × (gate width). The value of the fixed capacitor C3 can be arbitrarily adjusted by selecting the thickness t OX of the gate insulating films (12, 16) and the area ratio of the area S AA of the active region to the area S1 of the central lower electrode 17c. Therefore, the value of Equation (4) can be adjusted to the required value within a range up to about 1 / 2 by selecting the thickness t OX and the size S AA of the active region. Thus, by selecting the DC bias voltage V bias to a predetermined value and choosing the structure of the audible range sensor for the stethoscope so as to adjust the value of d(ε r / t OX ) in Equation (4), the gate voltage of the nMOSFET can be selected so that the nMOSFET operates in the linear region.

[0076] The problem is whether, when a characteristic audible range signal indicating the characteristics of the object to be diagnosed is applied and the upper electrode 25c is slightly displaced, a change ΔV3 in the gate voltage corresponding to the slight displacement Δd of the upper electrode 25c can be obtained for the gate voltage of the nMOSFET. From Equation (2), when the electrode distance d between the upper electrode 25c and the central lower electrode 17c is displaced by Δd, the change ΔC1 in the capacitance value of the first variable capacitor C1 is C1 + ΔC1 = ε0S1 / (d - Δd) ………(5) can be expressed as. On the other hand, Equation (4) is [Mathematics] It can be rewritten as follows. When the multivariable function of Equation (6) is partially differentiated with respect to ∂d, [Mathematics] It can be seen that it becomes as follows. Equation (7) is a multivariable function having variables d and t OX and the like.

[0077] When focusing on the variable d, it can be seen that the change ΔV3 in the gate voltage of the nMOSFET when the electrode distance d between the upper electrode 25c and the central lower electrode 17c is displaced by Δd can be expressed in the form of the following Equation (8). [Mathematics] From Equation (8), in order to increase the change ΔV3 in the gate voltage when the electrode distance d is displaced by Δd, the relative permittivity ε r of the gate insulating film is increased, the film thickness t OX of the gate insulating film is made thinner and the electrode distance d is made thinner, and further, the DC bias voltage V bias which is the first potential is increased. Conventional capacitive elements such as cMUT detect the change in charge which is a quantity variable. However, since the value per element of the charge which is a quantity variable becomes small due to element miniaturization, when the size of each element is miniaturized to realize an inexpensive electronic stethoscope, difficulties in receiving circuit implementation follow.

[0078] On the other hand, according to the audible range sensor targeted by the first embodiment illustrated in FIG. 5, since the change in voltage which is a quantity variable shown in Equation (8) is detected in the central lower electrode 17c, the value does not become small even if the element is miniaturized. Since Equation (8) is a multivariable function, when focusing on the value of ε r / t OX as a variable, the absolute value of Equation (8) is a convex-up function having a maximum value when ε r / t OX = 1 / d. That is, the film thickness t OXis such that when the electrode distance d is multiplied by the relative permittivity (ε r ), the function value representing the absolute value of Equation (8) reaches its maximum. Therefore, it is advisable to reduce the thickness t OX of the gate insulating film in accordance with the electrode distance d. However, reducing the thickness t OX of the gate insulating film or the electrode distance d has limitations in terms of manufacturing technology and physical properties. Considering Equation (8), it can be seen that increasing the DC bias voltage V bias is effective in increasing the change ΔV3 in the gate voltage with respect to the change in Δd.

[0079] Previously, it was explained using Equation (4) that by selecting the DC bias voltage V bias which is the first potential, the operating point of the gate voltage can be selected so that the nMOSFET operates in the linear region. From the requirements of Equation (8), if the DC bias voltage V bias is increased too much, the operating point will deviate from the linear region. Insulated-gate SITs such as MOSSIT and MISSIT that exhibit the drain voltage-drain current characteristics of a triode have a linear region for all operating regions. Therefore, it can be seen that the first embodiment is preferable as an insulated-gate semiconductor device for an audible range sensor.

[0080] Using the mutual conductance g m of the MOSFET, the change ΔI ds in the drain current I ds can be expressed as

Equation

[0081] By incorporating an insulated-gate semiconductor device such as an nMOSFET as an element of the audible range sensor targeted by the first embodiment, the insulated-gate semiconductor device is driven by the voltage generated by capacitance division at the central lower electrode 17c, and the current change ΔI ds It can be seen that the displacement of the upper electrode 25c can be detected as. Since the value of the change ΔV3 in the gate voltage of the nMOSFET shown in Equation (7) is a function that temporarily decreases as the electrode distance d between the upper electrode 25c and the central lower electrode 17c increases, it is preferable that the electrode distance d is smaller. On the other hand, as already explained, the thickness t OX When considering the thickness t as a variable, the function showing the absolute value of Equation (7) shows a convex upward curve shape and has a maximum value.

[0082] Therefore, considering the curve shape of the multivariable function showing the absolute value of the change ΔV3 in the gate voltage when the thickness t OX is a variable, there is an optimum value for the thickness t OX of the gate insulating film that depends on the electrode distance d. When the electrode distance d is reduced and the thickness t OX of the gate insulating film as the optimum value becomes smaller, the breakdown voltage of the gate insulating film becomes smaller. Therefore, the existence of the optimum value of the thickness t OX of the gate insulating film that depends on the electrode distance d will be explained. For this reason, if the reciprocal (ε r ) = x of the thickness t OX of the gate insulating film normalized by the relative dielectric constant ε r of the gate insulating film, the multivariable function of Equation (7) can be rewritten as OX ) = x, the multivariable function of Equation (7) is

Equation

[0083] In Equation (10), f(x) = x and g(x) = (1 + dx) 2 . Let the derivative of the differentiation of f(x) with respect to x be f x (x), and the derivative of the differentiation of g(x) with respect to x be g x (x). Then f x (x) = 1 ………(11) g x(x) = 2d + 2d 2 x = 2d(1 + dx) ………(12) Therefore, f x (x)g(x) - f(x)g x (x) = (1 + dx) 2 -2xd(1 + dx) = 1 - d 2 x 2 ………(13) It becomes like this.

[0084] Using Equation (13), the result of partially differentiating the multi-variable function of Equation (7) with respect to the variable x is

Number

[0085] Making the value of Equation (14) zero for d 2 x 2 = 1 is equivalent to dx = 1. Therefore, the multi-variable function showing the absolute value of the gate voltage change ΔV3 shown in Equation (7) and Equation (10) is d / ε0 = t OX / ε0ε r ………(15) means that it reaches the maximum value at this time. That is, when the electrode distance between the first variable capacitor C1 and the fixed capacitor C3 normalized by their respective dielectric constants are equal to each other, the absolute value of the gate voltage change ΔV3 becomes the maximum value. This means that when the values of the first variable capacitor C1 and the fixed capacitor C3 are equal as can be seen from Equation (2) and Equation (3), the function showing the absolute value of the gate voltage change ΔV3 of the nMOSFET shown in Equation (7) reaches the maximum value.

[0086] Figure 6D shows an n + type source region (first main electrode region) 15b and an n +The structure in which the drain region (second main electrode region) 15a of the type is opposed across the surface of the channel formation region 14 is shown as a large-signal equivalent circuit compared with a general nMOSFET. Also in FIG. 6D, compared with the structure shown in FIG. 5, on the channel regions of the first main electrode region (source region) 15b and the second main electrode region (drain region) 15a, there is a thickness T OX2 of the first gate insulating film 12 and a thickness T OX1 of the second gate insulating film 16, and a central lower electrode 17c serving as a gate electrode is provided through a two-layer gate insulating film (12, 16). A source electrode S is connected to the first main electrode region (source region) 15b, and a drain electrode D is connected onto the second main electrode region (drain region) 15a, respectively.

[0087] Similar to a general nMOSFET, between the central lower electrode 17c serving as a gate electrode and the first main electrode region 15b, there is a gate-source capacitance C gs as shown in FIG. 6D. Between the central lower electrode 17c and the second main electrode region 15a, there is a gate-drain capacitance C gd and between the central lower electrode 17c and the channel formation region 14, there is a gate-substrate capacitance C OX . Further, between the first main electrode region 15b and the channel formation region 14, there is a source-substrate capacitance C Bs and between the second main electrode region 15a and the channel formation region 14, there is a drain-substrate capacitance C Bd .

[0088] In a conventional capacitive MEMS element such as a cMUT, there has been a problem that when ultrasonic waves are input to the MEMS element, the deflection of the upper electrode and the cavity vibration film does not become uniform. That is, a downward convex shape in which the upper electrode and the lower electrode are not close to each other except in the vicinity of the center of the vibration cavity 28 becomes a problem. For example, in the structure shown in FIG. 7, unless some countermeasures are taken, the electrode distance between the upper electrode 25c and the peripheral lower electrode 17o at the position around the central lower electrode 17c tends to be larger than the electrode distance d between the upper electrode 25c and the central lower electrode 17c near the center of the vibration cavity 28.

[0089] Therefore, in the structure shown in FIG. 7, in the cavity forming insulating film 20 that surrounds the vibrating cavity 28 as a drum-shaped sealed space, the relative permittivity ε of the silicon oxide film r = 3.9 to 4.5, a silicon nitride film with a relative permittivity higher than that (ε r = 7.0 to 7.8) is inserted as the electric field strengthening layer 19, thereby improving the problem of the bending shape in which the curvature of the central portion of the cavity vibrating film 23 becomes large. Similarly, a silicon nitride film is selected as the highly rigid insulating film with high rigidity, and this silicon nitride film is adopted as the rigidity strengthening lid portion 31c on the upper electrode protection film 26 as shown in FIG. 7. Further, also in the cavity vibrating film 23 directly below the upper electrode 25c, with a rigidity strengthening structure using a silicon nitride film, the curvature in which the cavity vibrating film 23 bulges downward can be further reduced.

[0090] As described above, by using an array of a plurality of audible range sensors X ij each having a mechanical resonance frequency in the audible range, the target characteristic audible range signal can be efficiently detected as a voltage signal. In particular, when each of the plurality of audible range sensors X ij integrates an insulated gate type semiconductor as an internal structure, the detected characteristic audible range signal can be further self-amplified by the electrostatic induction effect depending on the internal structure. Therefore, according to the electronic stethoscope according to the first embodiment, even in an environment where the characteristic audible range signal serving as a sound source is weaker than the noise level, a high SN ratio can be achieved, and an electronic stethoscope with high objectivity and auscultation accuracy can be realized.

[0091] (Second Embodiment) In the electronic stethoscope according to the first embodiment, as shown in FIG. 3A and the like, a cushion film 93 is provided on the bottom surface of the housing 92a, and an example of a structure similar to that of a conventional acoustic stethoscope that forms an air layer between the cushion film (housing vibrating film) 93 and the signal input surface is illustrated. In the electronic stethoscope according to the first embodiment, the characteristic audible range signal generated from the diagnostic object 1 once propagates to the air layer, and what becomes air vibration in the air layer is the audible range sensor X ijIt is captured in this way. Therefore, the acoustic impedance is significantly different between the diagnostic object 1 and the air layer, and the sensitivity is greatly reduced. Further, if an air layer is formed between the buffer film 93 shown in FIG. 3A and the signal input surface, the air inside the air layer thermally vibrates and becomes an unnecessary noise source. Therefore, the sound collection unit 9b of the electronic stethoscope according to the second embodiment of the present invention directly contacts the surface of the diagnostic object 1 such as a living body with the plate-like portion on the bottom surface side, which is a part of the outer skin of the housing 92b, as shown in FIGS. 15 and 16 described later. The housing 92b forms a storage cavity for storing a plurality of audible range sensors X having respective mechanical resonance frequencies in the audible range on the flat plate-like portion of the outer skin on the bottom surface side. ij is formed so as to be surrounded by the outer skin.

[0092] Referring to FIG. 5 described in the first embodiment, the resonance frequencies that are the peaks of the frequency dependence curves of the reception sensitivities of the drum-shaped audible range sensors (audible range electroacoustic transducers) and the six factors that determine the frequency characteristics are arranged in order of importance as follows: (First factor) The rigidity ratio of each material constituting the vibrating parts (23, 25c, 26, 34); (Second factor) The thickness of each plate constituting the vibrating parts (23, 25c, 26, 34); (Third factor) The diameter of the vibrating parts (23, 25c, 26, 34); (Fourth factor) The support rigidity of the cavity-forming insulating film 20; (Fifth factor) The value of the sensitivity adjustment resistor R aij ; and (Sixth factor) The height of the vibrating cavity 28 result.

[0093] In FIGS. 15 and 16 described later, the resonance frequencies of the audible range sensors X v1 ~X v4 and the audible range sensors X w1 ~X w5 whose resonance frequencies are nearly one digit different are described as a structure built inside the housing 92b that constitutes the sound collection unit 9b of the electronic stethoscope. Therefore, before explaining the specific structure of the electronic stethoscope according to the second embodiment, without passing through an air layer like the electronic stethoscope according to the first embodiment, the audible range sensors X ijThe simulation results such as the reception sensitivity (voltage sensitivity) when directly contacting the surface of the diagnostic object 1 such as a living body are explained. The simulation used the "piezoelectric wave analysis software PZFlex" first developed by Weidlinger Associates in the United States. In the simulation, both the vibration of the mechanical vibration cavity accompanying the input of the characteristic audible range signal and the electrical vibration accompanying the changes in the first variable capacitor C1 and the second variable capacitor C2 due to this mechanical vibration are considered. Considering the vibration of the drum in the drum-shaped audible range sensor, the circle can be approximated as a shape similar to the topology of the hexagonal drum-shaped detection part shown in FIG. 4.

[0094] In the simulation, the audible range sensor X housed inside the housing 92b that constitutes the sound collecting part 9b of the stethoscope v1 ~X v4 and the audible range sensor X w1 ~X w5 is considered for the case of making the resonance frequencies non-uniform. In this case, if the individual chips of the audible range sensor X v1 ~X v4 and the individual chips of the audible range sensor X w1 ~X w5 are manufactured in the same manufacturing process, the first, second, fourth, and sixth factors are common, and by changing the planar pattern dimensions of the third factor, it is convenient to change the resonance frequencies of the audible range sensor X v1 ~X v4 and X w1 ~X w5 Note that, similar to the description of the first embodiment, in the following description of the second embodiment, the audible range sensor X v1 ~X v4 and X w1 ~X w5 will be described by the collective expression of "audible range sensor X ij " as needed.

[0095] The solid and dashed-dotted curves shown in Fig. 8 represent the case where the dimensions of the planar pattern, which is the third factor determining the frequency characteristics, are changed. Each of the solid and dashed-dotted lines in Fig. 8 corresponds to a diagram showing the result of simulating the reception sensitivity (voltage sensitivity) of an audible range sensor having a pattern in which a circular central lower electrode is concentrically and separably arranged in a circular donut-shaped peripheral lower electrode. Audible range sensor X having a concentric split gate structure ij The voltage change of the central lower electrode in is shown on the left vertical axis of Fig. 8 as the reception sensitivity, and the horizontal axis shows the frequency change.

[0096] However, the solid and dashed-dotted lines in Fig. 8 show the simulation results when the amplification function of the insulated gate semiconductor element incorporated in the audible range sensor as shown in Equation (9) is ignored. That is, it should be noted that the reception sensitivity is shown assuming that the change ΔV3 in the gate voltage of the insulated gate semiconductor element as shown in Equation (8) is output as it is. Also, on the assumption that an upper electrode protection film 26 made of a Si3N4 film with a thickness of 10.0 μm is provided over the entire surface on the upper electrode 25c and on the cavity formation insulating film 20 surrounding the vibration cavity 28. A tip protection film 34 made of room temperature curable silicone rubber with a thickness of 0.2 mm is provided on the upper electrode protection film 26, constituting the vibrating part (25c, 26, 34). However, different from the structure illustrated in Fig. 5, the presence of the cavity vibration film 23 directly under the upper electrode 25c is omitted in the vibrating part (25c, 26, 34).

[0097] In the simulation, similar to the drum-shaped structure shown in Fig. 5, the cavity formation insulating film 20 made of a SiO2 film is arranged so as to surround the vibration cavity 28 that defines the drum-shaped detection part, and supports the edges (periphery) of the vibrating part (25c, 26, 34). Different from the structure shown in Fig. 7, in the simulation, the electric field strengthening layer 19o made of a Si3N4 film around the vibration cavity 28 is not used. The curve shown by the solid line in Fig. 8 sets the height of the vibration cavity 28, which is the sixth factor determining the frequency characteristics, to 4.4 μm. On the other hand, the curve shown by the dashed-dotted line in Fig. 8 sets the height of the vibration cavity 28 to 3.8 μm. The height of the vibration cavity 28 corresponds to the "barrel height" of the drum.

[0098] Moreover, in the electronic stethoscope according to the second embodiment, different from the first embodiment, the sound (characteristic audible range signal) generated within the diagnostic object 1 such as a living body is listened to by bringing the sound collection unit 9a into contact with the surface of the diagnostic object 1 as shown in FIG. 16 described later, without passing through an air layer. The frequency characteristics of the electronic stethoscope according to the second embodiment depend on the configuration of the diagnostic object 1 such as a living body which is an elastic body and the sound collection unit 9a. The resonance frequency changes according to the mass of the sound collection unit 9a and the elastic constant of the diagnostic object 1. It should also be noted that the simulation results shown by the solid line and the alternate long and short dash line in FIG. 8 approximate the elastic constant etc. of the diagnostic object 1 with the physical properties of water which occupies most (about 60% by weight) of the living body.

[0099] Similar to the concentric hexagonal topology shown in FIG. 4, for the concentric separation pattern in which the circular central lower electrode 17c is arranged at a distance from the peripheral lower electrode 17o inside the circular opening provided at the center of the circular pattern that becomes the outer peripheral lower electrode 17o, the frequency dependence of the sensitivity characteristics was simulated. The solid line in FIG. 8 indicates that the diameter of the circular central lower electrode 17c is 0.94 mm Φ and the diameter of the outer peripheral lower electrode 17o is 3 mm Φ and the inner diameter of the peripheral lower electrode 17o and the outer diameter of the central lower electrode 17c are separated by 94 μm in the diameter direction. Therefore, the solid line in FIG. 8 is the case where the outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o and the central lower electrode 17c is also 3 mm Φ and the outer diameter of the vibrating part (25c, 26, 34) as the third factor constituted by the upper electrode 25c, the upper electrode protective film 26 and the tip protective film 34 is 3 mm Φ is.

[0100] The alternate long and short dash line in FIG. 8 indicates that the diameter of the circular central lower electrode 17c is 0.625 mm Φ and the diameter of the outer peripheral lower electrode 17o is 2 mm Φ and the inner diameter of the peripheral lower electrode 17o and the outer diameter of the central lower electrode 17c are separated by 62.5 μm in the diameter direction. In the case of the alternate long and short dash line, the outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o and the central lower electrode 17c is also 2 mm ΦAs a result, the outer diameter of the vibrating part (25c, 26, 34) formed by the upper electrode 25c, the upper electrode protective film 26, and the tip protective film 34 is 2 mm Φ There is a 20.2 μm thick field insulating film made of SiO2 film provided under each of the peripheral lower electrode 17o and the central lower electrode 17c. Inside the 20.2 μm thick field insulating film, an active region defined by S AA =(gate length)×(gate width) can be defined, and a gate insulating film of an insulated gate semiconductor element with a thickness of about 100 nm can be formed inside the active region. In the simulation shown in FIG. 8, the upper electrode 25c that forms part of the drum-shaped detection part is connected to the sensitivity adjustment resistor R aij =100 MΩ resistor is grounded.

[0101] In the simulation shown in FIG. 8, as described above, the solid line represents the height of the vibration cavity 28 being 4.4 μm, and the dashed-dotted line represents the height of the vibration cavity 28 being 3.8 μm. Both the solid line and the dashed-dotted line show the results of simulation with a DC bias voltage V bias of 50 V applied as the first potential between the upper electrode 25c and the peripheral lower electrode 17o. Audible range sensor X v1 ~X v4 and X w1 ~X w5 When manufacturing each individual chip of ~X w5 in the same manufacturing process, it is convenient to make the height of the vibration cavity 28, which is the sixth factor determining the frequency characteristics, common. When the height of the vibration cavity 28 of the sixth factor is made common, in addition to the first to sixth factors, it is preferable to significantly change the DC bias voltage V bias applied as the seventh factor. On the other hand, in the simulation shown in FIG. 8, since a common DC bias voltage V bias is applied to a plurality of audible range sensors, when the DC bias voltage V bias is constant, it is necessary to change the sixth factor.

[0102] The outer diameter of the vibrating part (25c, 26, 34) shown by the solid line in FIG. 8 is 3 mm ΦThe sensitivity curve in this case achieves a reception sensitivity of 3.0 mV / Pa at around 65 Hz. Below around 65 Hz, the reception sensitivity is 3.0 mV / Pa or higher. The sensitivity curve shown by the solid line starts to decrease as the frequency increases from the value of 3.0 mV / Pa at around 65 Hz, and reaches a minimum value of 2.2 mV / Pa at around 110 Hz. After reaching the minimum value, it turns to increase, reaches a maximum value of 2.7 mV / Pa at around 320 Hz, and then decreases again as the frequency increases, forming an S-shaped curve. The peak of the sensitivity curve that reaches the maximum value at around 320 Hz in Fig. 8 indicates the mechanical resonance frequency, and it can be seen that the resonance frequency exists near the approximate center of the audible range.

[0103] For the main diagnostic band of about 20 Hz to 710 Hz shown in Fig. 12, it can be seen that a reception sensitivity of 2.1 mV / Pa or higher can be obtained in the band of 65 to 700 Hz included in the main diagnostic band. As already explained, the sensitivity characteristics shown in Fig. 8 are the simulation results when ignoring the amplification function of the insulated gate semiconductor element incorporated in the audible range sensor. Considering the amplification factor of the insulated gate semiconductor element that functions as the mutual conductance g m etc., a reception sensitivity more than one digit higher than 2.1 mV / Pa can be expected. Therefore, the audible range sensor for the electronic stethoscope according to the second embodiment can achieve extremely high sensitivity.

[0104] The dashed-dotted line in Fig. 8 is the sensitivity characteristic of the audible range sensor X with a split gate structure having an outer diameter of 2 mm for the vibrating parts (25c, 26, 34). Φ It has a bowl-shaped curve shape that is convex upward, where the reception sensitivity gradually increases as the frequency increases from around 50 Hz, reaches a maximum value of 1.05 mV / Pa at around 1 kHz, and then decreases again as the frequency increases. The peak of the sensitivity curve that reaches the maximum value at around 1 kHz in Fig. 8 indicates the mechanical resonance frequency, and it can be seen that the resonance frequency exists in the audible range. The outer diameter of the vibrating parts (25c, 26, 34) is 2 mm ij Φ ​When this is the case, it can be seen that a reception sensitivity of 0.25 to 1.0 mV / Pa is obtained in the frequency band of 50 to 700 Hz included in the main auscultation band. Considering the amplification factor of the insulated-gate semiconductor device that functions as the mutual conductance g of the MOSFET shown in Equation (9), a reception sensitivity that is more than one order of magnitude higher than 0.25 to 1.0 mV / Pa can be expected. Therefore, even when the diameter is 2 mm m it can be seen that the audible range sensor for the electronic stethoscope according to the second embodiment can achieve extremely high sensitivity. Φ Regarding the noise that is a problem in the electronic stethoscope, as shown in FIG. 9A, there are 1 / f noise that is inversely proportional to the frequency f and shot noise (white noise) that is independent of the frequency f. As shown in FIG. 9A, since the 1 / f noise decreases as the frequency increases, the amount of noise becomes equal to the white noise at a corner frequency fcnr of about 200 Hz. At frequencies higher than the corner frequency fcnr, white noise becomes the main component, and at lower frequencies, 1 / f noise becomes the main component. In the electronic stethoscope according to the second embodiment, the reception sensitivity is increased by adjusting the value of the sensitivity adjustment resistor R

[0105] and the value of the DC bias voltage V aij so that the curve showing the frequency dependence characteristic of the reception sensitivity is positioned in the upper right region of the noise characteristic shown in FIG. 9A so as to include the peak of the resonance frequency, thereby realizing a high SN ratio. bias As an example of the characteristic audible range signal shown in the upper part of FIG. 9A, the I sound is generated immediately after the start of the systolic phase of the heart and is mainly due to the closure of the mitral valve, and the frequency band of 30 to 120 Hz is mainly involved. The I sound may include a component of the tricuspid valve closure, often splits, and is high-pitched. The II sound is said to be generated by the closure of the aortic valve and the pulmonary valve at the start of the diastolic phase of the heart, and the main frequency band is said to be 70 to 150 Hz. The II sound is said to have been discovered by René Laennec introduced at the beginning. On the other hand, the I sound was discovered in 1616, 200 years ago.

[0106]

[0107] ​In the upper part of FIG. 9A, furthermore, as examples of characteristic audible range signals, diastolic noise from the aortic valve and noise due to mitral regurgitation in the frequency band of 180 Hz to 710 Hz, and respiratory vibrations in the frequency band of 210 Hz to 630 Hz are shown to be the objects of auscultation by the electronic stethoscope. As for the respiratory vibrations, the loudness of the breath sound, the difference between the left and right, and abnormalities in the auscultation site are examined. The abnormality in the auscultation site means that bronchial sounds can be heard at the alveolar breath sound auscultation site. Note that when the electronic stethoscope according to the second embodiment is used for detecting characteristic audible range signals due to abnormalities in mechanical devices, cracks in structures, etc., it is not limited to the frequency bands of the characteristic audible range signals shown in the upper part of FIG. 9A.

[0108] In Non-Patent Document 1, using the heart sound of a human recorded with a phonocardiograph as a sound source, the sound pressure spectrum of the heart sound felt in the ear was measured through a conventional acoustic stethoscope (non-electronic stethoscope), and the results as shown in FIG. 9B were reported. According to FIG. 9B, the conventional bell-type stethoscope indicated by the white square shows a bell-shaped spectrum distribution that is convex upward at 24 Hz to 500 Hz and shows a maximum value at about 68 Hz. On the other hand, the conventional diaphragm-type (membrane-type) stethoscope indicated by the white triangle shows a bell-shaped spectrum distribution that is convex upward at 40 Hz to 400 Hz and shows a maximum value at about 130 Hz. Non-Patent Document 1 points out that "below 100 Hz, the diaphragm-type stethoscope has a sound pressure about 20 to 25 dB lower than that of the bell-type stethoscope, and the diaphragm-type stethoscope acts as a high-pass filter." In view of the pointed-out content of Non-Patent Document 1, it can be estimated that the heart sound used as the sound source is close to the bell-shaped spectrum shape with a maximum value at about 68 Hz in FIG. 9B.

[0109] FIG. 9B shows that in a conventional acoustic stethoscope, the shape, size, and internal structure of the stethoscope affected the sensitivity characteristics. In the medical field, when listening to heart sounds and heart murmurs with a bell-type stethoscope, if the pressure of the stethoscope on the surface of the chest wall, which forms part of the diagnostic object 1, is increased as shown in FIG. 3A, high-frequency sounds can be heard clearly. If the pressure is decreased as shown in FIG. 3B, low-frequency sounds can be heard clearly. Therefore, it is said to be suitable for screening. On the other hand, it is often mistakenly thought that low sounds such as galloping sounds cannot be heard with a diaphragm-type stethoscope. In fact, it is pointed out that the diaphragm-type stethoscope is better at conducting sound from a solid object to a solid object and is excellent for listening to various sounds.

[0110] As already mentioned, generally, the frequency characteristics of a stethoscope are determined by the living body, which is an elastic body, and the configuration of the sound collecting part 9a. There is a resonance frequency determined by the mass of the sound collecting part 9a and the elastic constant of the living body or the like. Above this resonance frequency, the sound to be listened to attenuates as the frequency increases. Even if the vibration generated in the living body has a certain magnitude (acceleration) with respect to the frequency, the magnitude of the sound listened to with the stethoscope depends on the mass below the resonance frequency and does not depend on the mass above the resonance frequency but depends on the amplitude of the vibration. Since the amplitude of the vibration is inversely proportional to the square of the frequency, even if the vibration generated in the living body has a certain magnitude with respect to the frequency, it attenuates inversely proportional to the square of the frequency above the resonance frequency.

[0111] As shown in FIG. 1A, when there is an acoustic tube 7 between the sound collecting part 9a and the outer ear mounting part 6, due to the propagation characteristics of the acoustic tube 7, high-frequency sounds attenuate. The resonance frequency of a conventional general acoustic stethoscope is at most about several hundred Hz, and the sensitivity rapidly attenuates at frequencies above several hundred Hz. Therefore, for sounds such as Sound I and Sound II in the band of about 300 Hz or less shown in the upper part of FIG. 9A, in a conventional acoustic stethoscope, by increasing the weight of the stethoscope, the sensitivity below the resonance frequency is increased and the auscultation accuracy is improved. Similarly, in an acoustic stethoscope, sounds from the respiratory organs, diastolic murmurs from the aortic valve, and murmurs due to mitral valve regurgitation shown in the upper part of FIG. 9A have a rapidly attenuating sensitivity at frequencies above about 300 Hz.

[0112] Therefore, in the prior art of auscultation using an acoustic stethoscope, there has been a problem that high-frequency sounds of about 300 Hz are masked by low-frequency sounds and cannot be heard. The problem that high-frequency sounds of about 300 Hz are masked by low-frequency sounds and cannot be heard is the same for conventional electronic stethoscopes. This is because the reception sensitivity of conventional electronic stethoscopes is more than one order of magnitude lower than that of the electronic stethoscope according to the second embodiment, and a high signal-to-noise ratio (SN ratio) cannot be achieved. According to the electronic stethoscope according to the second embodiment, as shown by the solid line and the alternate long and short dash line in FIG. 8, a high reception sensitivity can be achieved even at about 300 Hz or higher. Therefore, even when the characteristic audible range signal serving as the sound source is weak, the auscultation accuracy can be increased by achieving a high SN ratio.

[0113] The solid line in FIG. 10A indicates that the diameter of the circular central lower electrode 17c is 0.75 mm Φ and the diameter of the peripheral lower electrode 17o is 2.4 mm Φ The inner diameter of the peripheral lower electrode 17o and the outer diameter of the central lower electrode 17c are separated by 75 μm in the diameter direction. The outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o and the central lower electrode 17c is also 2.4 mm Φ The outer diameter of the vibrating part (25c, 26, 34) as the third factor constituted by the upper electrode 25c and the like is 2.4 mm Φ The alternate long and short dash line in FIG. 10A indicates that the diameter of the circular central lower electrode 17c is 0.375 mm Φ and the diameter of the peripheral lower electrode 17o is 1.2 mm Φ The inner diameter of the peripheral lower electrode 17o and the outer diameter of the central lower electrode 17c are separated by 37.5 μm in the diameter direction.

[0114] In the case of the alternate long and short dash line in FIG. 10A, the outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o and the like is also 1.2 mm Φ The outer diameter of the vibrating part (25c, 26, 34) as the third factor constituted by the upper electrode 25c and the like is 1.2 mm ΦIt is so. A field insulating film made of SiO2 with a thickness of 9.2 μm is provided under each of the peripheral lower electrode 17o and the central lower electrode 17c. Inside the field insulating film with a thickness of 9.2 μm, S AA =(gate length)×(gate width) defines an active region, and a gate insulating film of an insulated gate semiconductor element with a thickness of about 100 nm can be formed inside the active region. The upper electrode 25c that forms part of the drum-shaped detection part is grounded through a sensitivity adjustment resistor R aij = 100 MΩ. The solid line in Fig. 10A shows the result of simulation with a DC bias voltage V bias of 11 V applied as the first potential between the upper electrode 25c and the peripheral lower electrode 17o.

[0115] In the simulation shown in Fig. 10A, a cavity-forming insulating film 20 made of SiO2 film is arranged to surround the vibration cavity 28, and in both the simulations of the solid line and the dashed-dotted line, the height of the vibration cavity 28, which is the sixth factor, is unified to 2.0 μm. The white squares shown in the cross-sections of the audible range sensors X v2 and X v4 shown in Fig. 16 are schematic representations with exaggerated heights. Each of the actual vibration cavities is a flat square with a width of about 2.4 mm and a height of about 2 μm. Similarly, the white square in the cross-section of the audible range sensor X w1 shown in Fig. 16 is a flat square with a width of about 1.2 mm and a height of about 2 μm, and the height is hardly visible. And an upper electrode protection film 26 made of a Si3N4 film with a thickness of 10.0 μm is provided on the entire surface above the upper electrode 25c and above the cavity-forming insulating film 20 surrounding the vibration cavity 28. A tip protection film 34 made of room-temperature-curing silicone rubber with a thickness of 0.2 mm is provided on the upper electrode protection film 26. Similar to the explanation in Fig. 8, the upper surface of the tip protection film 34 is simulated under the condition of being in contact with water that occupies most of the living body.

[0116] As shown in Fig. 15 inside the housing, audible range sensors X v1 ~X v4 and X w1 ~X w5When arranging, the audible range sensor X v1 ~X v4 and X w1 ~X w5 If the respective individual chips of and are manufactured in the same manufacturing process, the manufacturing cost can be reduced. Audible range sensors X with different resonance frequencies v1 ~X v4 and X w1 ~X w5 When manufacturing in the same manufacturing process, it is convenient to make the height of the vibration cavity 28 of the sixth factor common. When the height of the vibration cavity 28 is made common, in addition to the first to sixth factors that determine the frequency characteristics, the DC bias voltage V of the seventh factor bias needs to be changed significantly. The solid line in Fig. 10A indicates that the outer diameter (diameter) of the vibrating parts (25c, 26, 34) = 2.4 mm Φ , DC bias voltage V bias = 11V, and the dashed-dotted line indicates that the outer diameter of the vibrating parts (25c, 26, 34) = 1.2 mm Φ , DC bias voltage V bias = 45V.

[0117] The sensitivity characteristic shown by the solid line in Fig. 10A achieves a reception sensitivity of 1.0 mV / Pa at about 95 Hz. Below about 95 Hz, the reception sensitivity is 1.0 mV / Pa or more. The sensitivity curve shown by the solid line starts to decrease as the frequency increases from the value of the reception sensitivity of 1.0 mV / Pa at about 95 Hz, and becomes a minimum value of 0.78 mV / Pa at about 140 Hz. After reaching the minimum value, it turns to increase, becomes a maximum value of 0.88 mV / Pa at about 350 Hz, and then decreases again as the frequency increases, forming an S-shaped curve. The peak of the sensitivity curve that reaches the maximum value at about 350 Hz in Fig. 10A indicates the mechanical resonance frequency, and it can be seen that the resonance frequency exists near the center of the audible range. For the main diagnostic band of about 20 Hz to 710 Hz shown in Fig. 12, the outer diameter (diameter) of the vibrating parts (25c, 26, 34) = 2.4 mm Φ , DC bias voltage V biasWhen the voltage is 11V, it can be seen that a reception sensitivity of 0.78 mV / Pa or more can be obtained in the frequency band of 95 to 700 Hz included in the main diagnosis band. However, considering the amplification factor of the built-in insulated gate semiconductor element, a reception sensitivity more than one digit higher than 0.78 mV / Pa can be expected.

[0118] The audible range sensor X indicated by the dashed-dotted line in FIG. 10A ij The sensitivity characteristic has a bowl-shaped curve shape that is convex upward, where the reception sensitivity gradually increases as the frequency increases from about 50 Hz, reaches a maximum value of 0.35 mV / Pa at about 5.3 kHz, and then decreases again as the frequency increases. The peak of the sensitivity curve that reaches the maximum value at about 5.3 kHz in FIG. 10A indicates the mechanical resonance frequency, and it can be seen that the resonance frequency exists in the audible range and is approaching the high-frequency end of the audible range. The outer diameter (diameter) of the vibrating parts (25c, 26, 34) = 1.2 mm Φ , and the DC bias voltage V bias When the voltage is 45V, it can be seen that a reception sensitivity of 0.025 to 0.1 mV / Pa can be obtained in the frequency band of 50 to 700 Hz included in the main diagnosis band. However, considering the amplification factor of the built-in insulated gate semiconductor element, a reception sensitivity more than one digit higher than 0.025 to 0.1 mV / Pa can be expected. According to the electronic stethoscope according to the second embodiment, as shown by the solid line and the dashed-dotted line in FIG. 10A, a high reception sensitivity can be achieved even at about 300 Hz or more. Therefore, even when the characteristic audible range signal serving as the sound source is weak, the stethoscope accuracy can be increased by achieving a high SN ratio.

[0119] The solid line in FIG. 10B is the same as in FIG. 10A, and the diameter of the circular central lower electrode 17c is 0.75 mm Φ , and the outer diameter (diameter) of the vibrating parts (25c, 26, 34) is 2.4 mm Φ The dashed-dotted line in FIG. 10B is the same as in FIG. 10A, and the diameter of the circular central lower electrode 17c is 0.375 mm Φ , and the outer diameter of the vibrating parts (25c, 26, 34) is 1.2 mm Φ The upper electrode 25c is also grounded with a resistor of the sensitivity adjustment resistor R aij = 100 MΩ, which is the same as in FIG. 10A.

[0120] Furthermore, in the simulation shown in FIG. 10B, similar to FIG. 10A, a field insulating film made of SiO2 with a thickness of 9.2 μm is provided under each of the peripheral lower electrode 17o and the central lower electrode 17c. An active region is defined inside the field insulating film with a thickness of 9.2 μm, and a gate insulating film of an insulated gate semiconductor element with a thickness of about 100 nm can be formed inside the active region. Also, a cavity-forming insulating film 20 made of SiO2 is arranged so as to surround the vibrating cavity 28. In both the solid line and the dashed-dotted line in FIG. 10B, the height of the vibrating cavity 28, which is the sixth factor determining the frequency characteristics, is unified to 2.0 μm. Then, an upper electrode protection film 26 made of a Si3N4 film with a thickness of 10.0 μm is provided over the entire surface on the upper electrode 25c and on the cavity-forming insulating film 20 surrounding the vibrating cavity 28. A tip protection film 34 made of room-temperature-curing silicone rubber with a thickness of 0.2 mm is provided on the upper electrode protection film 26. Similar to FIG. 10A, the simulation is that the upper surface of the tip protection film 34 is in contact with water.

[0121] However, the solid line in FIG. 10B shows the simulation result when a DC bias voltage V bias of 4V is applied as the first potential between the upper electrode 25c and the peripheral lower electrode 17o. The sensitivity curve shown by the solid line in FIG. 10B is different from the frequency-dependent characteristic of the reception sensitivity shown by the solid line in FIG. 10A, and the peak of the sensitivity curve showing the maximum value is not prominent. That is, the outer diameter (diameter) of the vibrating part (25c, 26, 34) shown by the solid line in FIG. 10B = 2.4 mm Φ , the DC bias voltage V biasWhen the DC bias voltage V = 4V, the sensitivity characteristic achieves a reception sensitivity of 1.0 mV / Pa at around 130 Hz, and the reception sensitivity is 1.0 mV / Pa or more below around 130 Hz. The sensitivity curve shown by the solid line starts to decrease from the reception sensitivity of 1.0 mV / Pa at around 130 Hz, and becomes an inflection value of about 0.6 mV / Pa at around 210 Hz. After becoming the inflection value, it forms a gentle decreasing shoulder up to around 430 Hz, and then forms a sigmoid curve that decreases as the frequency increases. The shoulder that appears on the higher frequency side than 210 Hz in Fig. 10B corresponds to the mechanical resonance frequency, and it can be seen that the mechanical resonance frequency exists near the center of the audible range. For the main diagnostic band of about 20 Hz to 710 Hz shown in Fig. 12, the outer diameter (diameter) of the vibrating parts (25c, 26, 34) = 2.4 mm Φ , the DC bias voltage V bias In the case of V = 4V, it can be seen that a reception sensitivity of about 0.48 mV / Pa or more can be obtained in the frequency band of 130 to 700 Hz included in the main diagnostic band. However, considering the amplification factor of the insulated gate type semiconductor element, a reception sensitivity more than one digit higher than 0.48 mV / Pa can be expected.

[0122] The dashed-dotted line in Fig. 10B is the sensitivity characteristic of the audible range sensor X with the outer diameter of the vibrating parts (25c, 26, 34) = 1.2 mm in the split gate structure Φ , the DC bias voltage V bias = 16V ij As the frequency increases from around 50 Hz, the reception sensitivity gradually increases, reaches a maximum value of 0.29 mV / Pa at around 3.6 kHz, and then decreases again as the frequency increases, forming a convex-upward bowl-shaped curve. The peak of the sensitivity curve that reaches the maximum value at around 3.6 kHz in Fig. 10B indicates the mechanical resonance frequency in the case of the outer diameter = 1.2 mm Φ , and it can be seen that the resonance frequency exists in the audible range, but as the outer diameter = 1.2 mm Φ it approaches the high-frequency side end of the audible range. The outer diameter of the vibrating parts (25c, 26, 34) = 1.2 mm Φ , the DC bias voltage V biasWhen = 16V, it can be seen that a reception sensitivity of 0.04 to 0.11 mV / Pa can be obtained in the frequency band of 50 to 700 Hz included in the main auscultation band. However, considering the amplification factor of the insulated gate semiconductor element, the outer diameter = 1.2 mm Φ , DC bias voltage V bias When = 16V, a reception sensitivity more than one digit higher than 0.04 to 0.11 mV / Pa can be expected. According to the electronic stethoscope according to the second embodiment, as shown by the solid line and the alternate long and short dash line in FIG. 10B, a high reception sensitivity can be achieved even at about 300 Hz or higher. Therefore, even when the characteristic audible range signal serving as the sound source is weak, the auscultation accuracy can be increased by achieving a high SN ratio.

[0123] Audible range sensor X ij The resonance frequency of is determined by the product of the capacitance C1 formed by the drum-shaped structure and the sensitivity adjustment resistor R aij (the fifth factor) that grounds one of the electrodes of the capacitance C1. The time constant C1·R aij also changes accordingly. When the time constant C1·R aij is set to be approximately the same as the mechanical resonance frequency determined by the first, second, third, and fourth factors, broadband characteristics can be obtained as an audible range sensor. When the height of the vibration cavity 28 of the sixth factor changes, the capacitance C1 also changes, so the time constant C1·R aij also changes, and as a result, the resonance frequency changes. FIG. 11A shows the audible range sensor X ij with the split gate structure shown in FIG. 4 and the like. The voltage change of the central lower electrode 17c is used as the reception sensitivity, and the change when the value of the sensitivity adjustment resistor R aij is changed is shown. The diameter of the inner central lower electrode 17c is 0.625 mm Φ , the diameter of the peripheral lower electrode 17o is 2.0 mm Φ , and the simulation is performed with the electrode distance d = 1.5 μm between the upper electrode 25c and the central lower electrode 17c. The outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o and the like is also 2.0 mm Φ , and the outer diameter of the vibration part (25c, 26, 34) as the third factor formed by the upper electrode 25c and the like is 2.0 mm Φ .

[0124] That is, a cavity-forming insulating film 20 made of an SiO2 film is arranged to surround the vibration cavity 28, and the height of the vibration cavity 28, which is the sixth factor determining the frequency characteristics, is set to 1.5 μm. On the other hand, a field insulating film made of an SiO2 film with a thickness of 6.9 μm is provided under each of the peripheral lower electrode 17o and the central lower electrode 17c. An active region is defined inside the field insulating film with a thickness of 6.9 μm, and a gate insulating film of an insulated gate semiconductor element with a thickness of about 100 nm can be formed inside the active region. Then, an upper electrode protection film 26 made of a Si3N4 film with a thickness of 10.0 μm is provided over the entire surface on the upper electrode 25c and on the cavity-forming insulating film 20 surrounding the vibration cavity 28. A tip protection film 34 made of a room-temperature-curing silicone rubber with a thickness of 0.2 mm is provided on the upper electrode protection film 26. Similar to FIGS. 8, 10A, and 10B, the simulation is performed under the condition that the upper surface of the tip protection film 34 is in contact with water having an elastic constant close to that of the living body, which is the diagnostic object 1.

[0125] FIG. 11A shows that as the value of the sensitivity adjustment resistor R aij which is the fifth factor, is sequentially decreased step by step from R aij = 100 MΩ → 50 MΩ → 20 MΩ → 10 MΩ → 5 MΩ → 2 MΩ, the value indicating the peak (mechanical resonance frequency) on the maximum side of the curve showing the frequency dependence of the reception sensitivity gradually decreases. That is, the peak value on the maximum side of the curve showing the frequency dependence decreases from a value of about 0.65 mV / Pa when the sensitivity adjustment resistor R aij = 100 MΩ to about 0.05 mV / Pa when the sensitivity adjustment resistor R aij = 2 MΩ. Also, as the sensitivity adjustment resistor R aij for grounding the upper electrode 25c is sequentially decreased step by step from R aij = 100 MΩ → 50 MΩ → 20 MΩ → 10 MΩ → 5 MΩ → 2 MΩ, it can be seen that the center frequency of the resonance peak appearing on the maximum side of the frequency dependence curve moves to the high-frequency side. That is, the center frequency of the resonance peak appearing on the maximum side of the frequency dependence curve decreases from a value of about 600 Hz when the sensitivity adjustment resistor R aij = 100 MΩ to the sensitivity adjustment resistor R aij = 2 MΩ. aijAt 2 MΩ, it is about 4 kHz.

[0126] FIG. 11B shows the voltage change of a uniform lower electrode without a split gate structure when it has a drum-shaped structure of an upper electrode and a lower electrode similar to that of a cMUT, as the voltage reception sensitivity, and the sensitivity adjustment resistor R aij shows the change when the value of is changed. The diameter of the uniform lower electrode is 2.0 mm Φ and the outer diameter of the upper electrode 25c facing the lower electrode is also 2.0 mm Φ The outer diameter of the vibrating part (25c, 26, 34) as the third factor constituted by the upper electrode 25c, etc. is 2.0 mm, the same as in the case of FIG. 11A Φ And as in the case of FIG. 11A, a field insulating film made of SiO2 with a thickness of 6.9 μm is provided under the lower electrode. An active region is defined inside the field insulating film with a thickness of 6.9 μm, and a gate insulating film of an insulated gate semiconductor element with a thickness of about 100 nm can be formed inside the active region. Also, a cavity-forming insulating film made of SiO2 is arranged so as to surround the vibrating cavity, and the height of the vibrating cavity is set to 1.5 μm. Then, an upper electrode protection film made of a Si3N4 film with a thickness of 10.0 μm is provided on the entire surface above the upper electrode and on the cavity-forming insulating film surrounding the vibrating cavity. A tip protection film made of room-temperature-curing silicone rubber with a thickness of 0.2 mm is provided on the upper electrode protection film. Similar to FIG. 11A, the simulation is carried out under the condition that the upper surface of the tip protection film 34 is in contact with water having an elastic constant close to that of the living body, which is the diagnostic object 1.

[0127] In the case of the structure where the lower electrode shown in FIG. 11B is not divided, the sensitivity adjustment resistor R aij = 20 MΩ → 10 MΩ → 5 MΩ → 2 MΩ → 1 MΩ → 500 kΩ, and as the value of the sensitivity adjustment resistor R aij for grounding the uniform lower electrode is sequentially decreased step by step, the value indicating the peak (mechanical resonance frequency) on the maximum side of the curve showing the frequency dependence of the voltage detection reception sensitivity decreases compared to the peak value of the sensitivity curve in the case of the sensitivity adjustment resistor R aij = 20 MΩ. In the case of the audible range sensor X ijの with the split gate structure of FIG. 11A, the sensitivity adjustment resistor R aijWhen it is 20 MΩ, the peak value of the voltage reception sensitivity was about 0.33 mV / Pa. However, when it does not have the split gate structure of FIG. 11B, the sensitivity adjustment resistor R aij At 20 MΩ, the peak value of the voltage reception sensitivity decreases to about 0.25 mV / Pa, which is about 2 / 3. However, the data shown in FIGS. 11A and 11B do not take into account the amplification factor of the insulated gate semiconductor device as shown in Equation (9). Audible range sensor X ij Taking into account the amplification factor of the insulated gate semiconductor device incorporated in the audible range sensor X, the voltage reception sensitivity of the audible range sensor for an electronic stethoscope according to the second embodiment is actually one digit or more higher than that in the case of FIG. 11B. Therefore, when comparing with the same value of the sensitivity adjustment resistor R aij the audible range sensor X having the insulated gate semiconductor device of FIG. 11A ij means that the voltage reception sensitivity is significantly higher than that in the case of the structure having no insulated gate semiconductor device shown in FIG. 11B.

[0128] Even in the structure where the lower electrode shown in FIG. 11B is integrated, as the sensitivity adjustment resistor R aij changes from 20 MΩ → 10 MΩ → 5 MΩ → 2 MΩ → 1 MΩ → 500 kΩ in sequence and the value of the sensitivity adjustment resistor R aij decreases step by step, it can also be seen that the center frequency of the resonance peak appearing on the maximum side of the frequency dependence curve moves from about 440 Hz when the sensitivity adjustment resistor R aij is 20 MΩ to the high frequency side of about 3.0 kHz. When it has the split gate structure of FIG. 11A, when the sensitivity adjustment resistor R aij is 20 MΩ, the center frequency of the resonance peak appearing on the maximum side of the frequency dependence curve was 1.03 kHz. However, in the case of the drum-shaped element having no split gate structure of FIG. 11B, when the sensitivity adjustment resistor R aij is 20 MΩ, the center frequency of the resonance peak decreases to 440 Hz.

[0129] When it has the split gate structure of FIG. 11A, the sensitivity adjustment resistor R that grounds the upper electrode 25c aijWhen it was 2 MΩ, the center frequency of the resonance peak that appeared on the maximum side of the frequency dependence curve was about 4.0 kHz. On the other hand, in the case of the drum-shaped element without the split gate structure of FIG. 11B, the sensitivity adjustment resistor R aij = 2 MΩ, the center frequency of the resonance peak decreased to 1.05 kHz. Therefore, the audible range sensor X having the split gate structure applied to the electronic stethoscope according to the second embodiment shown in FIG. 11A ij tends to have a higher center frequency of the resonance peak compared to the structure of the drum-shaped element without the split gate structure shown in FIG. 11B for the same value of the sensitivity adjustment resistor R aij . It can be seen that the center frequency of the resonance peak of all the curves shown in FIG. 11B when there is no split gate structure tends to shift to the lower frequency side compared to the center frequency of the resonance peak of the curve of the audible range sensor X shown in FIG. 11A ij .

[0130] FIG. 12 shows the frequency bands of characteristic audible range signals caused by various physiological parameters to be targeted by the electronic stethoscope according to the second embodiment. Already, in the description of FIG. 9A, "the first heart sound and the second heart sound", "respiration", and "aortic and mitral regurgitation" have been mentioned. The characteristic audible range signal S3, which is the second from the bottom in the left frequency region of FIG. 12, is the sound when blood rapidly flows from the atrium to the ventricle at the early stage of heart diastole, and the characteristic audible range signal S4 is the atrial systolic sound that occurs at the late stage of heart diastole. S3 and S4 can be heard best at the apex of the heart, and the characteristic audible range signal that sounds like "na·to·ku" is "S3 gallop", and the characteristic audible range signal that sounds like "wa·kat·ta" is "S4 gallop". S3 and S4 gallops are heart sounds that can be heard in a band of about 20 Hz to 60 Hz as shown in FIG. 12, and because of their low frequency, there was a problem that they were difficult to hear with conventional acoustic stethoscopes

[0131] Mitral stenosis is a pathological condition in which blood flow from the left atrium to the left ventricle is obstructed due to narrowing of the mitral valve orifice. The "mitral stenosis" shown in the frequency band of 23 to 75 Hz, the third from the bottom on the left side of FIG. 12, is a characteristic audible region signal characterized by a large S1 sound, an early diastolic valve opening sound, and a low-pitched crescendo-decrescendo diastolic rumble. The "diastolic rumble" is a low sound following the opening sound. The "gastrointestinal tract" shown in the frequency band of 56 to 420 Hz in the upper part of FIG. 12 means a characteristic audible region signal during auscultation of intestinal peristaltic sounds and the like. The "ejection murmur" shown in the frequency band of 120 to 420 Hz, the second from the top on the right side of FIG. 12, is regarded as a characteristic audible region signal generated by turbulent forward flow passing through a narrowed or irregular heart valve or outflow tract. The opposite of "ejection" is "regurgitation".

[0132] In FIG. 13A, the first adjustment resistor R o1 = 100 MΩ and the first switching element Q1 are connected in series to form a first series circuit, and the current flowing through the first adjustment resistor R o1 is configured to be controlled by the first switching element Q1. Then, the second adjustment resistor R o2 = 50 MΩ and the second switching element Q2 are connected in series, and a second series circuit connected in parallel to the first series circuit is formed, and the current flowing through the second adjustment resistor R o2 is configured to be controlled by the second switching element Q2. Further, the third adjustment resistor R o3 = 20 MΩ and the third switching element Q3 are connected in series, and a third series circuit connected in parallel to the first and second series circuits is formed, and the current flowing through the third adjustment resistor R o3 is configured to be controlled by the third switching element Q3..... And the k-th adjustment resistor R ok = 2 MΩ and the k-th switching element Q k are connected in series, and a k-th series circuit connected in parallel to the first to (k - 1)-th series circuits is formed, and the current flowing through the k-th adjustment resistor R ok is configured to be controlled by the k-th switching element Q k .

[0133] The sensitivity adjustment resistor R shown in FIG. 11A aij Considering the frequency dependence curves of a group of reception sensitivities with the sensitivity adjustment resistor R aij as a parameter, it can be understood that by changing the sensitivity adjustment resistor R aij when selecting a specific frequency band among various diagnostic frequency bands shown in FIG. 12, the sensitivity characteristics of the electronic stethoscope according to the second embodiment can be adjusted so as to obtain an optimal SN ratio for the specific frequency band. For example, as shown in FIG. 13A, the first adjustment resistor R o1 , the second adjustment resistor R o2 , the third adjustment resistor R o3 , ……, the k-th adjustment resistor R ok are prepared, and the corresponding first switching element Q1, second switching element Q2, third switching element Q3, ……, k-th switching element Q k are selectively switched and driven by the gate signal from the resistance adjustment circuit 89 to select a desired adjustment resistor R oj , then it becomes possible to select the value of the sensitivity adjustment resistor R aij so as to obtain an optimal SN ratio for the frequency bands of various physiological parameters shown in FIG. 12. The resistance adjustment circuit 89 can be controlled by the operation of the display / operation unit 5 provided in the sound collection unit 9a shown in FIG. 1A.

[0134] Alternatively, as shown in FIG. 13B, even if the gate voltage V D of a three-terminal semiconductor element having a drain current I D -drain voltage V G characteristic with a variable resistance characteristic is changed by the gate signal from the resistance adjustment circuit 89, it becomes possible to select the value of the sensitivity adjustment resistor R aij so as to obtain an optimal SN ratio for the frequency bands of various physiological parameters shown in FIG. 12. The I D -V D characteristic shown in FIG. 13B is the I D -V D characteristic of an SIT having a triode type I D -V DIt is an intermediate characteristic of an FET having characteristics, and can be realized by selecting the gate interval and the impurity density of the channel of the junction type SIT. Therefore, according to the stethoscope according to the second embodiment, by operating the display / operation unit 5 in FIG. 1A, an optimal SN ratio for various diagnostic frequency bands shown in FIG. 12 can be obtained, and even in an environment where the characteristic audible range signal serving as a sound source is weak, a high SN ratio can be achieved, and a diagnosis with high objectivity and auscultation accuracy can be performed.

[0135] As shown in FIG. 16 to be described later, the shape of the housing 92b of the stethoscope according to the second embodiment is cylindrical. Therefore, the curved surface that becomes the side surface of the cylinder, the flat surface that becomes the upper surface (ceiling surface) of the cylinder, and the flat surface that becomes the lower surface (bottom surface) of the cylinder respectively form the main part of the outer skin. In the housing 92b shown in FIG. 16, the flat plate-like portions are the upper and lower surfaces of the cylinder. However, in the sound collection unit 9b of the stethoscope according to the second embodiment, a "signal input surface" where a characteristic audible range signal is input is defined on a part of the lower surface. That is, in FIG. 16, the region where the bottom surface of the plate-like portion that forms a part of the outer skin of the housing 92b is in direct contact with the surface of the diagnostic object 1 such as a living body is defined as the "signal input surface". In the sound collection unit 9b of the stethoscope according to the second embodiment, a characteristic audible range signal such as a bio-audible range signal is detected by bringing the signal input surface defined on the bottom surface of the housing 92b into contact with the surface of the diagnostic object 1.

[0136] As can be seen from FIG. 16 to be described later, the housing 92b of the stethoscope according to the second embodiment does not include a buffer film (housing vibration film) 93 as shown in FIG. 3A etc., and therefore there is no air layer either. That is, in the stethoscope according to the second embodiment, since the bottom surface of the housing 92b is directly brought into contact with the surface of the diagnostic object 1 such as a living body, as the material of the housing 92b, for example, a soft plastic such as PVC can be adopted. However, considering the influence of the acoustic impedance on the characteristic audible range signal propagating through the bottom surface of the housing 92b, an elastic material such as the room temperature curable silicone rubber adopted as the material of the tip protective film 34 is preferable in simulations such as FIGS. 8, 10A, 10B, 11A and 11B.

[0137] FIG. 14 shows the audible range sensor X of the split gate structure ijIn this case, the frequency dependence of the reception sensitivity detected as the voltage change of the central lower electrode 17c is shown with the thickness of the tip protection film 34 provided on the upper electrode protection film 26 shown in FIG. 5 and the like as a parameter. Similar to FIGS. 8, 10A, 10B, 11A, and 11B, the upper surface of the tip protection film 34 is simulated under the condition of being in contact with water having an elastic constant close to that of the living body which is the object to be diagnosed 1. The tip protection film 34 is made of room temperature curable silicone rubber, and the thickness t of the room temperature curable silicone rubber is increased step by step as t = 0.2 mm → 0.5 mm → 1.0 mm → 2.0 mm → 5 mm → 2 mm, and the frequency dependence of the reception sensitivity for each thickness is shown. The value R of the sensitivity adjustment resistor for grounding the pattern of the upper electrode 25c which can be approximated to the drum-shaped detection part aij is set to a constant value of 20 MΩ.

[0138] In the simulation shown in FIG. 14, the diameter of the inner central lower electrode 17c is 0.625 mm Φ , the diameter of the outer peripheral lower electrode 17o is 2.0 mm Φ , and the simulation is performed with the inter-electrode distance d = 1.5 μm between the upper electrode 25c and the central lower electrode 17c. The outer diameter of the upper electrode 25c facing the peripheral lower electrode 17o etc. is also 2.0 mm Φ , and the outer diameter of the vibrating part (25c, 26, 34) as the third factor constituted by the upper electrode 25c etc. is 2.0 mm Φ . That is, the cavity forming insulating film 20 made of SiO2 film is arranged so as to surround the vibrating cavity 28 that defines the drum-shaped detection part, and the height of the vibrating cavity 28 which is the sixth factor is set to 1.5 μm. On the other hand, a field insulating film made of SiO2 film with a thickness of 6.9 μm is provided under each of the peripheral lower electrode 17o and the central lower electrode 17c. An active region is defined inside the field insulating film with a thickness of 6.9 μm, and a gate insulating film of an insulated gate semiconductor element with a thickness of 100 nm etc. can be formed inside the active region. And an upper electrode protection film 26 made of a Si3N4 film with a thickness of 10.0 μm is provided on the entire surface on the upper electrode 25c and on the cavity forming insulating film 20 surrounding the vibrating cavity 28.

[0139] According to the sensitivity curve of FIG. 14, the audible range sensor X with a built-in amplification elementij As the thickness t of the tip protective film 34 is gradually increased in the order of t = 0.2 mm → 0.5 mm → 1.0 mm → 2.0 mm, it can be seen that the position of the curve showing the frequency dependence of the reception sensitivity moves downward on the paper surface and the sensitivity decreases compared to the position of the sensitivity curve when the thickness t = 0.2 mm. The sensitivity curve shown by the solid line in Fig. 14 for the case of thickness t = 0.2 mm achieves a reception sensitivity of 0.23 mV / Pa at about 50 Hz. The solid line sensitivity curve for the case of thickness t = 2 mm starts to decrease as the frequency increases from the value of the reception sensitivity of 0.23 mV / Pa at about 50 Hz, and reaches a minimum value of 0.21 mV / Pa at about 93 Hz. After reaching the minimum value, it turns to an increase, reaches a maximum value of 0.275 mV / Pa at about 440 Hz, and then decreases again as the frequency increases, forming an S-shaped sensitivity curve. The peak indicating the maximum value of the solid line sensitivity curve in Fig. 14 at about 440 Hz represents the mechanical resonance frequency. Therefore, it can be seen that in the sensitivity curve for the case of t = 0.2 mm, the mechanical resonance frequency exists near the approximate center of the audible range.

[0140] On the other hand, for the audible range sensor X with a built-in amplification element shown by the dashed line in Fig. 14 for the case of thickness t = 0.5 mm ij the sensitivity curve achieves a reception sensitivity of 0.14 mV / Pa at about 50 Hz, then starts to decrease as the frequency increases, and reaches a minimum value of 0.065 mV / Pa at about 130 Hz. After reaching the minimum value, it gradually starts to increase, reaches a maximum value of 0.075 mV / Pa at about 1 kHz, and then forms a sensitivity curve similar to an S shape with both ends extended left and right like a sigmoid curve that decreases again as the frequency increases. The peak of the dashed line curve indicating the maximum value at about 1 kHz in Fig. 14 represents the mechanical resonance frequency. The maximum value of the sensitivity curve for the case of thickness t = 0.5 mm shown by the dashed line in Fig. 14 is about 1 / 4 of the maximum value of the sensitivity curve for the case of thickness t = 0.2 mm shown by the solid line, showing a sharp decrease in the maximum value between 0.2 mm and 0.5 mm. The shape near 1 kHz of the sensitivity curve for the case of thickness t = 0.5 mm shown by the dashed line in Fig. 14 is a gentle mound-like shape closer to being called a shoulder rather than a maximum value.

[0141] ​The audible range sensor X in the case of a thickness t = 1.0 mm shown by a dashed line in FIG. 14 ij The sensitivity curve is located below the sensitivity curve in the case of t = 0.5 mm. After achieving a reception sensitivity of 0.125 mV / Pa at around 50 Hz, it begins to decrease as the frequency increases and reaches a minimum value of 0.03 mV / Pa at around 160 Hz. After reaching the minimum value, it starts a gentle increase that is nearly a parallel line, reaches a maximum value of 0.045 mV / Pa at around 1 kHz, and then has an S-shaped curve that is close to a sigmoid curve and decreases again with the frequency. The peak of the dashed line indicating the maximum value at around 1 kHz in FIG. 14 corresponds to the mechanical resonance frequency. The maximum value of the sensitivity curve in the case of a thickness t = 1.0 mm shown by the dashed line is about 3 / 5 of the maximum value of the sensitivity curve shown in the case of a thickness t = 0.5 mm shown by the dotted line. It is not as large a change as between 0.2 mm and 0.5 mm, but there is a significant decrease. The shape near 1 kHz of the sensitivity curve in the case of a thickness t = 1.0 mm shown by the dashed line in FIG. 14 is a gentle mound that is closer to being called a shoulder rather than a maximum value.

[0142] And the audible range sensor X in the case of a thickness t = 2.0 mm shown by a chain double-dashed line in FIG. 14 ijThe sensitivity curve is located below the sensitivity curve for t = 1.0 mm. After achieving a reception sensitivity of 0.11 mV / Pa at around 50 Hz, it begins to decrease with frequency and reaches a minimum value of 0.03 mV / Pa at around 160 Hz. The minimum value at around 160 Hz is approximately the same as the minimum value of the thickness t = 1.0 mm indicated by the dashed line. The sensitivity curve for the case of thickness t = 2.0 mm has a shape similar to a sigmoid curve that, after reaching the minimum value, begins a gradual increase that is nearly parallel to a straight line, reaches a maximum value of 0.035 mV / Pa at around 800 Hz, and then decreases again with frequency. The peak of the sensitivity curve for the case of thickness t = 1.0 mm indicated by the dashed line that reaches the maximum value at around 800 Hz in Fig. 14 corresponds to the mechanical resonance frequency. The maximum value of the sensitivity curve for the case of thickness t = 2.0 mm indicated by the dash-dot line is a value slightly smaller than the sensitivity curve shown for the case of thickness t = 1.0 mm indicated by the dashed line, and the decrease is negligibly small compared to the change between 0.2 mm and 0.5 mm. The shape near 800 Hz of the sensitivity curve for the case of thickness t = 2.0 mm indicated by the dash-dot line in Fig. 14 is a gentle mound-like shape that is closer to being called a shoulder rather than a maximum value.

[0143] According to Fig. 14, when the thickness t is increased from t = 0.2 mm to 0.5 mm, the center frequency of the resonance peak appearing in the frequency dependence of the audible range sensor X incorporating the amplification element ij tends to shift to the high-frequency side. That is, the center frequency of the resonance peak appearing in the frequency dependence is at a position on the high-frequency side of about 1 kHz for t = 0.5 mm, starting from a value of about 440 Hz for t = 0.2 mm. However, when the thickness t is gradually increased in steps of 0.5 mm → 1.0 mm → 2.0 mm, the shift of the center frequency of the resonance peak appearing in the frequency dependence is not significant and rather tends to shift to the low frequency. That is, the center frequency of the resonance peak appearing in the frequency dependence is at about 800 Hz for t = 2 mm, starting from a value of about 1 kHz for t = 0.5 mm.

[0144] On the other hand, when the thickness t is increased from t = 0.2 mm to 0.5 mm, the position of the minimum value appearing in the frequency dependence moves to the high-frequency side. That is, in FIG. 14, the position of the minimum value appearing in the frequency dependence is about 93 Hz when the thickness t = 0.2 mm, and about 130 Hz when the thickness t = 0.5 mm. However, when the thickness t is gradually increased from 0.5 mm to 1.0 mm and then to 2.0 mm, the movement of the frequency position of the minimum value appearing in the frequency dependence is not significant. That is, the frequency position of the minimum value appearing in the frequency dependence is about 130 Hz when the thickness t = 0.5 mm, and about 160 Hz common to both when the thickness t = 1 mm and 2 mm, so the movement of the position of the frequency at which the minimum value occurs seems to have stopped.

[0145] As shown in FIGS. 15 and 16 and the like, the sound collection unit 9b of the electronic stethoscope according to the second embodiment is the audible range sensor X incorporating an amplification element, which is an individual element. v1 ,X v2 ,X v3 ,X v4 ,X w1 ,X w2 ,X w3 ,X wj ,X w4 and X w5 can be housed inside the housing 92b. Similar to the description in the paragraph of the first embodiment, the plane pattern of the vibration cavity 28 shown by the hidden line in FIG. 15 defines the plane pattern of the drum-shaped detection unit. The outer shape of each of the audible range sensors X ij is almost similar to the plane pattern of the vibration cavity 28. The outer and inner hidden lines in FIG. 15 show concentric hexagons, and the nine drum-shaped detection units form a hexagonal plane pattern. Each of the audible range sensors X ij has a mechanical resonance frequency in the audible range as shown in FIGS. 8, 10A, 10B, 11A and the like, so the reception sensitivity is high.

[0146] Different from the structure shown in FIG. 3A and the like, there is no need for a buffer film holding portion for holding the peripheral portion of the buffer film at the bottom of the outer peripheral side surface of the housing 92b, so the outer diameter of the housing 92b is smaller than the outer diameter of the sound collection unit 9a of the electronic stethoscope according to the first embodiment shown in FIG. 2. The audible range sensor X ijSimilar to the sound collection unit 9a of the electronic stethoscope according to the first embodiment, it can be configured as a semiconductor element having an amplification function of directly inputting and amplifying a characteristic audible range signal to the gate electrode. The sound collection unit 9b can be arranged in contact with or in proximity to a biological sample to be examined, such as the chest, abdomen, crotch of the patient's arm or leg, or any other body part of the patient.

[0147] The audible range sensor X incorporated in the sound collection unit 9b of the electronic stethoscope according to the second embodiment v1 ~X v4 and X w1 ~X w5 The reception sensitivity of... to... depends on dimensions such as the inner diameter and diagonal diameter occupied by the audible range sensor, as described in the electronic stethoscope according to the first embodiment. In the sound collection unit 9b of the electronic stethoscope according to the second embodiment, as shown in FIG. 15, the first audible range sensor X including a hexagonal drum-shaped detection unit having a first diagonal diameter w1 is arranged at the center of the element array unit of the sound collection unit 9b. And around the first audible range sensor X w1 , the second audible range sensor X v1 , the third audible range sensor X v2 , the fourth audible range sensor X v3 and the fifth audible range sensor X v4 each having a second diagonal diameter longer than the first diagonal diameter are arranged. The planar patterns of the second audible range sensor X v1 , the third audible range sensor X v2 , the fourth audible range sensor X v3 and the fifth audible range sensor X v4 are also the patterns of the hexagonal drum-shaped detection unit.

[0148] Furthermore, a sixth audible range sensor X v4 having a first diagonal diameter shorter than the second diagonal diameter is arranged between the fifth audible range sensor X v1 and the second audible range sensor X. Similarly, a seventh audible range sensor X w2 having a first diagonal diameter is arranged between the second audible range sensor X v1 and the third audible range sensor X v2 . And a seventh audible range sensor X w3 having a first diagonal diameter is arranged between the third audible range sensor X v2 and the fourth audible range sensor X v3An eighth audible range sensor X having a first diagonal diameter is disposed between them. w4 And a fourth audible range sensor X v3 and a fifth audible range sensor X v4 An ninth audible range sensor X having a first diagonal diameter is disposed between them. w5 The sixth audible range sensor X w2 The seventh audible range sensor X w3 The eighth audible range sensor X w4 And the ninth audible range sensor X w5 The planar pattern is also a pattern of a hexagonal drum-shaped detection part.

[0149] As shown in FIG. 15, the housing 92b of the electronic stethoscope according to the second embodiment houses a detection unit array in which a plurality of drum-shaped detection units having different diagonal diameters are arranged. The diagonal diameter of the first audible range sensor X w1 which is a drum-shaped detection unit located at the center of the detection unit array is smaller than the diagonal diameters of the second to fifth audible range sensors X w1 which are arranged around the first audible range sensor X v1 ~X v4 each having a drum-shaped detection unit. According to the planar layout of the detection unit array including the audible range sensors X v1 ~X v4 having a large diagonal diameter drum-shaped detection unit and the audible range sensors X w1 ~X w5 having a small diagonal diameter drum-shaped detection unit as shown by the hidden lines in FIG. 15, as can be seen from FIG. 8 and the like, the mechanical resonance frequencies of the audible range sensors X v1 ~X v4 and the audible range sensors X w1 ~X w5 are different from each other. That is, by intentionally shifting the respective mechanical resonance frequencies of the audible range sensors X v1 ~X v4 and the audible range sensors X w1 ~X w5 from each other in the array composed of a plurality of drum-shaped detection units, the frequency band of the electronic stethoscope according to the second embodiment can be expanded so that the overall reception sensitivity is increased.

[0150] FIG. 16 is a cross-sectional view taken in the XVI-XVI direction of FIG. 15, and a fifth audible range sensor X is disposed on the left side of the central first audible range sensor X w1 and a third audible range sensor X is disposed on the right side. A structure is shown in which v4 v4 v2 v2 Examples of the detailed cross-sectional structures of the fifth audible range sensor X and the third audible range sensor X are shown in FIG. 5 and the like. As shown in FIG. 16, the sound collecting part 9b of the stethoscope according to the second embodiment has a disk-shaped housing 92b provided with a housing cavity inside. And a recessed part is provided as a sensor fixing part on the lower surface side inside the housing 92b. The region of the bottom surface of the plate-like part that forms a part of the outer skin of the housing 92b facing the sensor fixing part becomes the "signal input surface" of the stethoscope according to the second embodiment. The first audible range sensor X v4 v2 v2 w1 w1 v2 v2 v4 v4 and the third audible range sensor X and the fifth audible range sensor X are fixed by housing their respective lower parts in the sensor fixing part.

[0151] Furthermore, inside the housing cavity formed by the housing 92b, a power supply circuit 96, a signal processing circuit 97, and a communication circuit 98 are incorporated. The power supply circuit 96, the signal processing circuit 97, and the communication circuit 98 may be configured as a hybrid integrated circuit using a printed circuit board or the like, or at least a part of the power supply circuit 96, the signal processing circuit 97, and the communication circuit 98 may be three-dimensionally mounted by bump connection or the like. As shown in FIG. 16, an antenna 99 is connected to the input / output terminals of the communication circuit 98. A dipole antenna, a spiral antenna, a planar antenna (patch antenna), or the like can be adopted for the antenna 99. The power supply circuit 96 supplies the necessary electrical energy to the nine audible range sensors X v1 ~X v4 and X w1 ~X w5 as well as the signal processing circuit 97 and the communication circuit 98. The signal processing circuit 97 processes the audible range sensors X with different sizes v1 ~X v4 and the audible range sensors X w1 ~X w5Receive the signals from , respectively, perform A / D conversion on the received signals, and execute signal processing such as smoothing the frequency characteristics and removing noise by digital technology.

[0152] The communication circuit 98 transmits the information signal-processed by the signal processing circuit 97 to various information systems 3 in real time, in the same manner as illustrated in FIG. 1A. For the communication between the sound collection unit 9b and the information system 3, wireless communication using electromagnetic waves in the 2.4 GHz band with an antenna power of 10 mW or less can be adopted. Through communication such as wireless communication, the information signal-processed by the signal processing circuit 97 is transmitted to the information system 3 in real time for easy visualization, and further, it can be stored in a database of an institution such as a database of an institution related to a hospital, a hospital, or a network of a hospital or a hospital, or a cloud-based health system. The information signal-processed by the signal processing circuit 97 can be accessed via wireless communication or the like by the information system 3 of an institution interested in various biological information caused by the heartbeat, respiration, blood flow, digestion, etc. of the patient through the communication circuit 98 built in the sound collection unit 9b. When the information system 3 is equipped with AI, highly objective auscultation becomes possible by making the AI machine-learn the information acquired by the electronic stethoscope according to the second embodiment.

[0153] The nine audible range sensors X shown in FIG. 15 v1 ~X v4 and X w1 ~X w5 are housed in the sensor fixing part, and by detecting and amplifying the characteristic audible range signal such as the bio-audible range signal, the characteristic audible range signal can be detected with sufficient signal strength even if the diameter of the housing 92b is short. By reducing the number of the audible range sensors X v1 ~X v4 and X w1 ~X w5 to less than the nine shown in FIG. 15, the outer diameter of the sound collection unit 9b can be miniaturized to an unprecedented size and auscultation can be performed well. The material of the housing 92b is not particularly limited, and it may be a hard resin or a metal such as Al or Ti. In order to enhance the adhesion to the surface of the diagnostic object 1 and the matching of the elastic impedance, an elastic material such as silicone rubber is desirable as the material of the housing 92b.

[0154] According to the sound collecting part 9b of the electronic stethoscope according to the second embodiment, as shown in FIG. 16, when the signal input surface defined on the bottom surface of the housing 92b comes into contact with the surface of the object 1 to be diagnosed, characteristic audible range signals such as biological sounds (biological audible range signals) are collected by the audible range sensor X inside the sound collecting part 9b v1 ~X v4 and X w1 ~X w5 and can be directly transmitted to X. In the sound collecting part 9b of the electronic stethoscope according to the second embodiment, an insulated gate type semiconductor element is integrated (integrated) as the internal structure of the audible range sensor with a built-in amplification element. Then, the change in capacitance due to the characteristic audible range signal directly input from the signal input surface of the housing 92b induces the charge on the surface of the channel formation region 14 of the insulated gate type semiconductor element and the change in potential associated with this charge. That is, the charge induced on the surface of the channel formation region 14 controls the height of the surface potential of the channel formation region 14 and realizes an amplification function as shown in Equation (9), so that extremely high reception sensitivity can be realized

[0155] The acoustic tube 7 and the outer ear mounting part 6 as exemplified in FIG. 1A are not essential for the electronic stethoscope according to the second embodiment. For example, as shown in FIG. 17, a disk-shaped sound collecting part 9b is brought into contact with the surface of the object 1 to be diagnosed alone, commands from the information system 3 of a hospital or a clinic are received wirelessly, and information such as the fetal heart rate, the maternal heart rate, uterine activity, and intrauterine pressure (IUP) acquired by the sound collecting part 9b can be wirelessly transmitted to the information system 3 of a hospital or a clinic in real time

[0156] Furthermore, in the sound collecting part 9b of the electronic stethoscope according to the second embodiment, the display / operation part 5 exemplified in FIG. 1A can also be omitted. The display / operation part 5 can be miniaturized into a simple function one and integrated inside the sound collecting part 9b. That is, via the communication circuit 98, from an external information system 3, the on / off of the power supply circuit, the sensitivity adjustment resistor R aijCommands such as adjustment, gain adjustment of the amplifier, control of the communication circuit, volume adjustment, and mode switching can be issued, so the display / operation unit 5 is not essential. Also, in the sound collection unit 9b of the electronic stethoscope according to the second embodiment, the processed information can be displayed on an external information system 3 via the communication circuit 98. When the display / operation unit 5 is miniaturized to have a simple function and integrated inside the sound collection unit 9b, for example, only the on / off of the power circuit may be performed by the display / operation unit 5, and it may have a function of only executing the display of the LED lamp indicating the operating state.

[0157] According to the electronic stethoscope according to the second embodiment, unlike the electronic stethoscope according to the first embodiment, there is no process of converting a sound wave, which is a characteristic audible range signal once radiated into the air from the diagnostic object 1, into an electrical signal, so the reception sensitivity is not sacrificed. That is, the characteristic audible range signal generated in the diagnostic object 1 is received as a sound wave in a viscoelastic body having an acoustic impedance close to that of the diagnostic object 1 without sacrificing the reception sensitivity, and the received sound wave is converted into an electrical signal, so the reception sensitivity is improved. Moreover, in the electronic stethoscope according to the second embodiment, since a plurality of audible range sensors X each having a mechanical resonance frequency in the audible range ij are used, by operating the plurality of audible range sensors X ij without passing through an air layer, the characteristic audible range signal can be efficiently detected as a voltage signal.

[0158] In particular, when each of the plurality of audible range sensors X ij has an insulated gate semiconductor integrated as its internal structure, the detected characteristic audible range signal can be further self-amplified by the electrostatic induction effect depending on the internal structure. Therefore, according to the electronic stethoscope according to the second embodiment, even in an environment where the characteristic audible range signal serving as the sound source is weaker than the noise level, a high SN ratio can be achieved, and an electronic stethoscope with high objectivity and auscultation accuracy can be realized.

[0159] (Third Embodiment) The electronic stethoscope according to the third embodiment of the present invention also has an audible range sensor X having a mechanical resonance frequency in the audible range, similar to the electronic stethoscopes according to the first and second embodiments.ij is used. Similar to the electronic stethoscope according to the second embodiment, the electronic stethoscope according to the third embodiment does not include a buffer membrane (housing vibration membrane) 93. FIG. 14 shows a chip-shaped audible range sensor X which is an individual element ij indicating that the thickness of the tip protection film 34 should be thinner. In the sound collection part 9b of the electronic stethoscope according to the second embodiment, the audible range sensor X is placed inside a recess provided as a sensor fixing part on the lower surface side inside the housing 92b ij is shown as an example of being housed. However, extrapolating the results of FIG. 14, it is not preferable that the layer of the lower surface of the housing 92b physically exists below the tip protection film 34 at the top of the audible range sensor X ij The housing 92c of the sound collection part 9c of the electronic stethoscope according to the third embodiment is an annular body (torus) in which two rectangles appear on both sides in the cross-sectional view of FIG. 19A (FIG. 19A is a cross-section viewed from the XVI-XVI direction of FIG. 18). The housing 92c is surrounded by an outer skin having a flat plate-like part at least partially, and a storage cavity is formed inside the outer skin.

[0160] Since the shape of the housing 92c shown in FIG. 19A etc. is a torus with a rectangular cross-section, the first curved surface that becomes the outer cylindrical surface, the second curved surface that becomes the inner cylindrical surface, the flat surface that becomes the upper surface (ceiling surface) of the torus part, and the flat surface that becomes the lower surface (bottom surface) of the torus part respectively form the main part of the outer skin. In the housing 92c shown in FIG. 19A etc., the flat plate-like parts are the upper surface and the lower surface of the torus part. However, in the electronic stethoscope according to the third embodiment, a "signal input surface" where characteristic audible range signals are input is defined on a part of the lower surface. As shown in FIG. 19B, the sound collection part 9c of the electronic stethoscope according to the third embodiment includes an adsorption auxiliary part 95 made of an elastic body such as silicone rubber at the center of the annular body and having a function of vacuum adsorption as an adsorption pad. FIG. 19c is a bird's-eye view of the adsorption auxiliary part 95. By pushing the central ring downward, the adsorption auxiliary part 95 as an adsorption pad can be adsorbed on the surface of the diagnostic object 1 such as a living body, so that the sound collection part 9c can be stably adsorbed on the surface of the diagnostic object 1 easily. By pulling the central ring upward with a finger, the sound collection part 9c can also be easily separated from the surface of the diagnostic object 1.

[0161] Then, as shown in FIG. 19A, the tip protection film 34 (see FIG. 5) of the audible range sensor X with a built-in amplification element, which is an individual element, is exposed from the bottom surface of the housing 92c so as to contact the diagnostic object 1. In the stethoscope according to the third embodiment, the audible range sensors X p1 ,X p2 ,X p3 ,……,X p8 exposed from the bottom surface of the housing 92c so as to contact the diagnostic object 1. In the stethoscope according to the third embodiment, the entire tip protection film of each of the audible range sensors X p1 ,X p2 ,X p3 ,……,X p8 constitutes the "signal input surface". The sound collecting unit 9c of the stethoscope according to the third embodiment enhances the reception sensitivity by detecting a signal when the tip protection film of the audible range sensor X p1 ,X p2 ,X p3 ,……,X p8 contacts the diagnostic object 1. Each of the audible range sensors X with a built-in amplification element p1 ,X p2 ,X p3 ,……,X p8 is a chip-shaped individual element having a hexagonal planar pattern with the same diagonal diameter (in the following description of the third embodiment, the collective expression of "audible range sensor X ij " will be adopted as needed).

[0162] As described in the paragraph of the first embodiment, inside the region of the pattern of the audible range sensor cell X shown in FIG. 18, the planar pattern of the vibration cavity shown as an inner hexagon by hidden lines respectively corresponds to the planar pattern of the drum-shaped detection part. That is, the eight inner hexagons shown in FIG. 18 respectively correspond to the planar patterns of the eight drum-shaped detection parts. As shown in FIG. 18, the sound collecting unit 9c of the stethoscope according to the third embodiment can arrange the audible range sensors X with a built-in amplification element ij at equal intervals on the circumference of the toroid divided into eight parts and house (build in) them inside the housing 92c. The audible range sensor X ij ij ​Similar to the sound collection unit 9a of the electronic stethoscope according to the first and second embodiments, it can be configured as a semiconductor element having an amplification function of directly inputting and amplifying a characteristic audible range signal to a gate electrode. The sound collection unit 9c uses the adsorption assistance unit 95 to adsorb to a biological sample for inspection purposes, such as the chest, abdomen, crotch of the patient's arm or leg, or any other body part of the patient, and can be easily detached after the examination is completed.

[0163] As shown in FIG. 19A, the sound collection unit 9c of the electronic stethoscope according to the third embodiment has an annular housing 92c that surrounds the adsorption assistance unit 95. The peripheral part of the adsorption assistance unit 95 is fixed to the lower part of the inner circumference of the toroid. The toroid formed by the housing 92c is a storage cavity as shown in FIG. 19B. And in the storage cavity of the toroid, eight hexagonal through-holes are provided at equal intervals along the lower surface of the storage cavity as sensor fixing parts. Therefore, the lower parts of the eight audible range sensors X ij are respectively housed inside the through-holes and fixed by an adhesive or the like according to the inner diameter of the through-holes. As shown in FIG. 19A, the bottom surface of the toroid that forms the bottom surface of the housing 92c is a flat and uniform plane. And the bottom surface of the toroid formed by the housing 92c and the flat surfaces of the tip protection films of the plurality of audible range sensors X ij are "aligned on the outer surface", and the bottom surface of the housing 92c forms a uniform annular surface. In the electronic stethoscope according to the third embodiment, as shown in FIG. 19B, the structure in which the tip protection film of the audible range sensor X ij is exposed so as to contact the diagnostic object 1 is expressed as "the tip protection film of the audible range sensor X ij is exposed on the signal input surface".

[0164] Furthermore, as shown in FIG. 19B, inside the storage cavity of the toroid formed by the housing 92c, a power supply circuit 96, a signal processing circuit 97, and a communication circuit 98 are built in. The power supply circuit 96 supplies the electrical energy required for the eight audible range sensors X ij as well as the signal processing circuit 97 and the communication circuit 98. The signal processing circuit 97 is a plurality of audible range sensors X ijReceives a signal from and performs signal processing on the received signal. The power supply circuit 96, the signal processing circuit 97, and the communication circuit 98 may be configured as a hybrid integrated circuit using a printed circuit board or the like, or at least a part of the power supply circuit 96, the signal processing circuit 97, and the communication circuit 98 may be three-dimensionally mounted by bump connection or the like.

[0165] The communication circuit 98 transmits the information signal-processed by the signal processing circuit 97 to various information systems 3 in real time, in the same manner as illustrated in FIG. 1A. For communication between the sound collection unit 9c and the information system 3, wireless communication using electromagnetic waves in the 2.4 GHz band with an aerial power of 10 mW or less can be adopted. Through communication such as wireless communication, the information signal-processed by the signal processing circuit 97 is transmitted to the information system 3 in real time for easy visualization. Various biological information caused by the patient's heartbeat, respiration, blood flow, digestion, etc. can be accessed by the information system 3 of an interested institution via wireless communication or the like.

[0166] The eight audible range sensors X shown in FIG. 18 ij are housed in through holes serving as sensor fixing portions on the side surface near the top of , and by detecting and amplifying characteristic audible range signals such as bio-audible range signals, even in a small-sized sound collection unit 9c with a short toroidal diameter of the housing 92c, the characteristic audible range signals can be detected with sufficient signal strength. By reducing the number of audible range sensors X ij to less than the eight shown in FIG. 18, the outer diameter of the sound collection unit 9c can be further reduced and miniaturized, and auscultation can still be performed well. The material of the housing 92c is not particularly limited, and may be, for example, a soft plastic such as PVC or a phthalate rubber using di-2-ethylhexyl phthalate (DEHP) as a plasticizer. Further, a hard resin or a metal such as Al or Ti may also be used. To enhance the adhesion to the surface of the diagnostic object 1 and the matching of the elastic impedance, an elastic material such as silicone rubber is desirable for the tip protective film.

[0167] According to the sound collection unit 9c of the electronic stethoscope according to the third embodiment, as shown in FIG. 19A, a plurality of audible range sensors X ijBy bringing each of the tip protective films into direct contact with the surface of the diagnostic object 1, characteristic audible signals such as biological sounds (biological audible range signals) can be efficiently detected and amplified by the audible range sensor X inside the sound collection unit 9c. As a result, even in an environment where the characteristic audible signal serving as the sound source is weaker than the noise level, a high SN ratio can be achieved, enabling a diagnosis with high objectivity and auscultation accuracy. ij This makes it possible to achieve a high SN ratio and perform a highly objective and accurate auscultation diagnosis even in an environment where the characteristic audible signal serving as the sound source is weaker than the noise level.

[0168] The audible range sensors X incorporated in the sound collection unit 9d of the electronic stethoscope according to the third embodiment q1 ~X q4 and X r1 ~X r4 The reception sensitivity of... depends on dimensions such as the inner diameter and diagonal diameter occupied by the audible range sensor, as described in the electronic stethoscope according to the first embodiment. In the electronic stethoscope according to the third embodiment, as shown in FIG. 20, the first audible range sensor X including a hexagonal drum-shaped detection portion having a first diagonal diameter respectively q1 , the second audible range sensor X q2 , the third audible range sensor X q3 and the fourth audible range sensor X q4 are arranged in order at positions that divide the circumference of the bottom of the torus of the sound collection unit 9d into four equal parts. And between the first audible range sensor X q1 and the second audible range sensor X q2 , the fifth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter r1 is arranged. Also, between the second audible range sensor X q2 and the third audible range sensor X q3 , the sixth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter r2 is arranged. Further, between the third audible range sensor X q3 and the fourth audible range sensor X q4 , the seventh audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter r3 is arranged, and between the fourth audible range sensor X q4 and the first audible range sensor X q1 , the eighth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter r4 is arranged.

[0169] The audible range sensor X incorporated in the sound collecting part 9e of the electronic stethoscope according to the third embodiment s1 ~X s3 、X t1 ~X t3 and X u1 ~X u3 The reception sensitivities of ~X are dependent on dimensions such as the inner diameter and diagonal diameter occupied by the audible range sensor, as described for the electronic stethoscope according to the first embodiment. In the electronic stethoscope according to the third embodiment, as shown in Fig. 21, the first audible range sensor X including a hexagonal drum-shaped detection part each having a first diagonal diameter s1 , the second audible range sensor X s2 and the third audible range sensor X s3 are arranged in order at positions that trisect the circumference of the bottom of the torus of the sound collecting part 9e. Then, as shown in Fig. 21, at a position rotated 40° clockwise on the circumference from the first audible range sensor X s1 , the fourth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter t1 is arranged. Also, at a position rotated 40° clockwise on the circumference from the second audible range sensor X s2 , the fifth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter t2 is arranged. Further, at a position rotated 40° clockwise on the circumference from the third audible range sensor X s3 , the sixth audible range sensor X having a second diagonal diameter shorter than the first diagonal diameter t3 is arranged.

[0170] The audible range sensor X having a drum-shaped detection part with a large diagonal diameter, as shown by the hidden line in Fig. 20 q1 ~X q4 and the audible range sensor X having a drum-shaped detection part with a small diagonal diameter r1 ~X r4 The detection part array including ~X, as can be seen from Fig. 8 etc., the mechanical resonance frequencies of the audible range sensors X q1 ~X q4 and the audible range sensors X r1 ~X r4 are different from each other. For this reason, among the arrays composed of a plurality of drum-shaped detection parts, the audible range sensors X q1 ~X q4 and the audible range sensors X r1 ~Xr4 By intentionally shifting the respective mechanical resonance frequencies of r4 from each other, the frequency band of the electronic stethoscope according to the third embodiment can be expanded so that the overall reception sensitivity is increased.

[0171] Furthermore, as shown in FIG. 21, a seventh audible range sensor X t1 having a third diagonal diameter shorter than the second diagonal diameter is arranged at a position rotated 40° clockwise on the circumference from the fourth audible range sensor X u1 . Also, an eighth audible range sensor X t2 having a third diagonal diameter shorter than the second diagonal diameter is arranged at a position rotated 40° clockwise on the circumference from the fifth audible range sensor X u2 . And a ninth audible range sensor X t3 having a third diagonal diameter shorter than the second diagonal diameter is arranged at a position rotated 40° clockwise on the circumference from the sixth audible range sensor X u3 . FIG. 14 shows that the thickness of the tip protection film provided on the upper electrode protection film 26 of the audible range sensor X ij should be thinner.

[0172] In the detection unit array including the audible range sensors X s1 to X s3 having a large diagonal diameter drum-shaped detection unit as shown by the hidden line in FIG. 21, the audible range sensors X t1 to X t3 having a medium diagonal diameter drum-shaped detection unit, and the audible range sensors X u1 to X u3 having a small diagonal diameter drum-shaped detection unit, the mechanical resonance frequencies of the audible range sensors X s1 to X s3 , the audible range sensors X t1 to X t3 , and the audible range sensors X u1 to X u3 are different from each other. Therefore, in the array composed of a plurality of drum-shaped detection units as shown in FIG. 21, the audible range sensors X s1 to X s3 , X t1 to X t3 , and X u1 to X u3By intentionally shifting the respective mechanical resonance frequencies of each of them relative to each other, the frequency band of the electronic stethoscope according to the third embodiment can be expanded so that the overall reception sensitivity is increased.

[0173] Even with the configuration shown in FIGS. 20 and 21, a plurality of audible range sensors X each having a mechanical resonance frequency in the audible range ij By bringing the respective tip protective films of the sensors into direct contact with the surface of the diagnostic object 1, characteristic audible range signals can be efficiently detected as voltage signals. In particular, when each of the plurality of audible range sensors X ij integrates an insulated gate semiconductor that amplifies the characteristic audible range signal as an internal structure, the detected characteristic audible range signal can be self-amplified by the electrostatic induction effect depending on the internal structure. Therefore, even in an environment where the characteristic audible range signal serving as the sound source is weaker than the noise level, a high SNR can be achieved, enabling diagnosis with high objectivity and auscultation accuracy. As described above, according to the electronic stethoscope according to the third embodiment, even in an environment where the characteristic audible range signal serving as the sound source is weaker than the noise level, an electronic stethoscope with a high SNR, high objectivity, and high auscultation accuracy can be realized.

[0174] (Fourth Embodiment) In the electronic stethoscopes according to the first to third embodiments described above, a hybrid mounting structure in which chip-shaped audible range sensors X that are individual elements ij are arranged on the signal input surface side of the lower surfaces of the housings 92a, 92b, 92c, etc. was described. In the electronic stethoscope according to the fourth embodiment of the present invention, as shown in FIGS. 22A and 22B, the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 including are monolithically integrated on the surface of a semiconductor chip (first semiconductor chip) 41a, which is different from the arrangement structure of the audible range sensors X that are individual elements in the electronic stethoscopes according to the first to third embodiments. As described in the paragraph of the first embodiment, the audible range sensor cells X shown in FIG. 22A ij ~X mv1 ~X mv4 and X mw1 ~X mw5Inside the area of the pattern, the planar pattern of the vibration cavity, each shown as an inner hexagon by hidden lines, corresponds to the planar pattern of the drum-shaped detection part.

[0175] That is, the nine inner hexagons shown in Fig. 22A correspond to each of the planar patterns of the nine drum-shaped detection parts, and the blank parts shown by the three white rectangles shown in Fig. 22B indicate the vibration cavities that become the drum-shaped detection parts. Similar to the first to third embodiments, the three white rectangles shown in Fig. 22B are schematic representations with exaggerated height, and the aspect ratio is different from the actual structure. Each of the actual vibration cavities is a flat rectangle with a width of about 1.2 to 2.4 mm and a height of about 2 μm, so the height is hardly visible. Audible range sensor cell X mv1 ~X mv4 and X mw1 ~X mw5 Each of them desirably includes an insulated gate semiconductor that amplifies the characteristic audible range signal as an internal structure, but it is not essential to include the insulated gate semiconductor as an internal structure.

[0176] As shown in Fig. 22B, the semiconductor chip 41a is flip-chip arranged so that the sensor array including the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 is located on the signal input surface side of the lower surface of the housing 92d of the sound collecting part. And the characteristic audible range signals are input to the upper electrodes of the respective drum-shaped detection parts of the monolithically integrated audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 and each of the upper electrodes vibrates to operate as a drum-shaped (capacitive) audible range sensor. Audible range sensor cell X mv1 ~X mv4 and X mw1 ~X mw5Each of them has a mechanical resonance frequency in the audible range, similar to the electronic stethoscope according to the first to third embodiments, so the reception sensitivity is high (see Fig. 8 etc.). The electronic stethoscope according to the fourth embodiment does not include the buffer membrane 93 described in the electronic stethoscope according to the first embodiment, similar to the electronic stethoscopes according to the second and third embodiments. Audible range sensor cell X mv1 ~X mv4 and X mw1 ~X mw5 Although the specific structure of each of them is not shown, when an insulated gate type semiconductor is integrated as the internal structure, it is the same as the drum-shaped structure shown in Fig. 5 already described. As described with reference to Fig. 14, the thickness of the tip protection film 34 (see Fig. 5) of the audible range sensor cell X mij should be thinner.

[0177] As shown in Fig. 22A, a first audible range sensor cell X including a hexagonal drum-shaped detection part having a first diagonal diameter is located at the center of a rectangular semiconductor chip 41a. mw1 The first audible range sensor cell X mw1 For an example of the detailed structure of the planar pattern, when an insulated gate type semiconductor is integrated as the internal structure, it is the same as Fig. 4 already described. However, the divided structure into the central lower electrode and the peripheral lower electrode illustrated in Fig. 4 is not necessarily essential. And, as shown in Fig. 22A, around the first audible range sensor cell X mw1 second audible range sensor cells X each having a second diagonal diameter longer than the first diagonal diameter mv1 , third audible range sensor cells X mv2 , fourth audible range sensor cells X mv3 and fifth audible range sensor cells X mv4 are monolithically integrated on the surface of the semiconductor chip 41a. The second audible range sensor cell X mv1 , third audible range sensor cell X mv2 , fourth audible range sensor cell X mv3 and fifth audible range sensor cell X mv4 can also adopt a hexagonal shape similar to that already illustrated in Fig. 4 for the planar pattern.

[0178] Furthermore, on the semiconductor chip 41a, the fifth audible range sensor cell X mv4and the second audible range sensor cell X mv1 a sixth audible range sensor cell X having a first diagonal diameter shorter than the second diagonal diameter between them mw2 is monolithically integrated. Similarly, the second audible range sensor cell X mv1 and the third audible range sensor cell X mv2 a seventh audible range sensor cell X having the first diagonal diameter between them mw3 is monolithically integrated with the third audible range sensor cell X mv2 and the fourth audible range sensor cell X mv3 an eighth audible range sensor cell X having the first diagonal diameter between them mw4 is monolithically integrated. And further, the fourth audible range sensor cell X mv3 and the fifth audible range sensor cell X mv4 a ninth audible range sensor cell X having the first diagonal diameter between them mw5 is monolithically integrated. The planar patterns of the sixth audible range sensor cell X mw2 , the seventh audible range sensor cell X mw3 , the eighth audible range sensor cell X mw4 and the ninth audible range sensor cell X mw5 can also adopt a hexagonal shape as already illustrated in FIG. 4.

[0179] An audible range sensor cell X mv1 ~X mv4 having a large diagonal diameter drum-shaped detection part as shown by the hidden line in FIG. 22A mw1 ~X mw5 and an audible range sensor cell X mv1 ~X mv4 having a small diagonal diameter drum-shaped detection part mw1 ~X mw5When integrating them onto a monolithic and identical semiconductor chip 41a to form an array, it is convenient to make the first, second, fourth, and sixth factors that determine the frequency characteristics, which have been described above, common, because this does not increase the number of processes. Therefore, even in the semiconductor chip 41a shown in FIGS. 22A and 22B, the resonance frequency is changed by varying the planar dimension, which is the third factor that determines the frequency characteristics. Then, by intentionally shifting the mechanical resonance frequencies of the respective audible range sensor cells in a monolithic integrated array composed of a plurality of drum-shaped detection parts from each other, the frequency band of the stethoscope according to the fourth embodiment can be expanded so that the overall reception sensitivity is increased.

[0180] In the following description, the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 are not individually shown as needed, and the expression "audible range sensor cell X mij " is adopted comprehensively for convenience. As shown in FIGS. 22A and 22B, the housing 92d of the sound collecting part of the stethoscope according to the fourth embodiment is a cylindrical shape in which the cross section cutting the center line of the circle is U-shaped (FIG. 22B is a cross section viewed from the IIXIIB-IIXIIB direction of FIG. 22A). The outer skin of the housing 92d corresponds to the part where the cross section is U-shaped, and the upper surface is a flat plate-like part (plane part), but the lower surface is shown schematically as having an open end. That is, FIG. 22B is a model diagram for explaining that a storage cavity is formed inside the outer skin having a U-shaped cross section. However, it should be noted that the schematic representation showing that the lower surface of the storage cavity is an open end and the storage cavity is like an open space does not show the actual mounting structure.

[0181] At the position of this open-ended lower surface, the semiconductor chip 41a has the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5By flip-chip arranging so as to face downward, the main area of the open end is closed. FIG. 22B is a schematic diagram for explaining that by arranging the semiconductor chip 41a, the accommodation cavity becomes a substantially closed space. Similar to a normal stethoscope, the electronic stethoscope according to the fourth embodiment is cleaned with a wiping cloth (alcohol swab) soaked in 70% isopropyl alcohol or a wipe with soapy water every time the examination of one patient is completed, and is regularly disinfected such as removing organic substances. Therefore, in the actual mounting structure, the lower surface of the housing 92d is not an open end, but a plate-shaped seal layer that fills the open portion of the lower surface is used to form a seal surface through which isopropyl alcohol and soapy water do not permeate, but it is not shown in FIG. 23B. The plate-shaped seal layer whose illustration is omitted is in contact with the lower surface and the outer surface of the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 . Considering the regular maintenance such as disinfection and cleaning in practical use, as shown in FIG. 16, the entire lower surface of the housing 92d may be covered with silicone rubber or the like.

[0182] And in the electronic stethoscope according to the fourth embodiment, a "signal input surface" where a characteristic audible range signal is input is defined in a part of the region corresponding to the lower surface of the substantially closed space formed by the housing 92d and the semiconductor chip 41a shown in FIG. 22B. Then, as shown in FIG. 22B, by exposing the tip protective films of the tops of the plurality of audible range sensor cells X mij monolithically integrated from the lower surface of the housing 92d, the tip protective films of the audible range sensor cells X mij can contact the surface of the diagnostic object 1 respectively. In other words, in the electronic stethoscope according to the fourth embodiment, the surface that collectively includes the tip protective films of the plurality of audible range sensor cells X mij exposed from the lower surface of the housing 92d so as to contact the diagnostic object 1 constitutes the signal input surface. The housing 92d of the sound collection part of the electronic stethoscope according to the fourth embodiment increases the reception sensitivity by the tip protective films of the plurality of audible range sensor cells X mij each contacting the diagnostic object 1 to detect signals.

[0183] Audible range sensor cell X mw1 ~X mw5 Each of them is an element of a monolithic integrated circuit forming a hexagonal planar pattern having the same first diagonal diameter, and the audible range sensor cell X mv1 ~X mv4 Each of them is an element of a monolithic integrated circuit forming a hexagonal planar pattern having the same second diagonal diameter. As shown in FIG. 22A, the housing 92d of the electronic stethoscope according to the fourth embodiment has a plurality of audible range sensor cells X corresponding to a plurality of drum-shaped detection portions having different diagonal diameters mij A semiconductor chip 41a in which a plurality of audible range sensor cells X are monolithically integrated is disposed at the center of the housing 92d. And the diagonal diameter of the first audible range sensor cell X having a drum-shaped detection portion disposed at the center of the semiconductor chip 41a mw1 is smaller than the diagonal diameters of the second to fifth audible range sensor cells X mw1 each having a drum-shaped detection portion and disposed around the first audible range sensor cell X mv1 ~X mv4

[0184] In addition, similar to the structure shown in FIGS. 24A and 24B to be described later, the housing 92d may be configured to form a closed cylindrical shape, and nine hexagonal through-holes may be provided along the lower surface of the storage cavity formed by the closed cylinder. When the outer skin of the closed cylindrical shape is configured, each of the nine audible range sensor cells X mij is inserted, and the tip protection film at the top of each of the audible range sensor cells X mij may be protruded or flush with the outer skin formed by the housing 92d so as to contact the diagnostic object 1

[0185] ​Further, as shown in FIG. 22B, a second semiconductor chip 42 is stacked on a semiconductor chip (first semiconductor chip) 41a via a plurality of gold (Au) bumps 51, and a third semiconductor chip 43 is stacked on the second semiconductor chip 42 via a plurality of gold bumps 52, constituting a three-dimensional integrated circuit. The three-layer stacked structure of the first semiconductor chip 41a, the second semiconductor chip 42, and the third semiconductor chip 43 is an example, and the three-dimensional integrated circuit may be constituted by a two-layer stacked structure of the first semiconductor chip 41a and the second semiconductor chip 42 with the third semiconductor chip 43 omitted.

[0186] Further, on the three-dimensional integrated circuit constituted by the first semiconductor chip 41a, the second semiconductor chip 42, and the third semiconductor chip 43, as shown in FIG. 22B, a pressure absorption layer 44a made of an elastic body is stacked so as to contact the ceiling surface of the storage cavity formed by the housing 92d. When the housing 92d is pressed against the diagnostic object 1, the pressure absorption layer 44a mv1 ~X mv4 and X mw1 ~X mw5 absorbs the pressure applied to each of them, and functions so that the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 are not damaged. A power circuit 96 is housed inside the pressure absorption layer 44a, constituting a three-dimensional integrated circuit and a three-dimensional hybrid integrated circuit with the first semiconductor chip 41a, the second semiconductor chip 42, and the third semiconductor chip 43.

[0187] The power circuit 96 supplies the electric energy necessary for nine audible range sensor cells X mij integrated on the first semiconductor chip 41a, a signal processing circuit integrated on the second semiconductor chip 42, and a communication circuit integrated on the third semiconductor chip 43. When the three-dimensional integrated circuit is constituted by a two-layer stacked structure, the power circuit 96 supplies the electric energy necessary for the communication circuit integrated on the second semiconductor chip 42. The signal processing circuit integrated on the second semiconductor chip 42 has a plurality of audible range sensor cells X mijReceives a signal from , performs A / D conversion on the received signal, and then executes processes such as smoothing the frequency characteristics by digital technology and signal processing such as noise processing.

[0188] As shown in FIG. 22B, a ring-shaped antenna 99 is disposed near the inner wall of the housing 92d inside the pressure absorption layer 44a. A dipole antenna, a spiral antenna, a planar antenna (patch antenna), or the like can be adopted for the antenna 99. Although illustration of wiring and the like is omitted, the communication circuit integrated in the third semiconductor chip 43 is electrically connected to the antenna 99 via bumps, surface wiring, or the like. When a three-dimensional integrated circuit is configured with a two-layer stacked structure, the communication circuit integrated in the second semiconductor chip 42 is electrically connected to the antenna 99.

[0189] Via the antenna 99, the communication circuit integrated in the third semiconductor chip 43 can transmit the information signal-processed by the signal processing circuit of the second semiconductor chip 42 to various information systems 3 in real time, similar to what is illustrated in FIG. 1A. When a three-dimensional integrated circuit is configured with a two-layer stacked structure, the communication circuit integrated in the second semiconductor chip 42 transmits the information signal-processed by the signal processing circuit integrated in the second semiconductor chip 42 to various information systems 3 in real time. For communication between the housing 92d of the sound collection unit and the information system, wireless communication using electromagnetic waves in the 2.4 GHz band with an aerial power of 10 mW or less can be adopted. Through wireless communication via the antenna 99 or the like, the information signal-processed by the signal processing circuit is transmitted to the information system in real time for easy visualization. Various biological information caused by the patient's heartbeat, respiration, blood flow, digestion, etc. can be accessed by the information system of an interested institution via wireless communication or the like.

[0190] The nine audible range sensor cells X shown in FIG. 22A mij By detecting a characteristic audible range signal such as a bio-audible range signal, even a small housing 92d with a short outer diameter can detect the characteristic audible range signal with sufficient signal strength. The audible range sensor cell X mijBy reducing the number to less than the nine shown in FIG. 22A, even if the outer diameter of the housing 92d of the sound collecting unit is further reduced for miniaturization, auscultation can be performed well. The material of the housing 92d is not particularly limited. For example, a soft plastic such as PVC or a phthalate rubber using DEHP as a plasticizer may be used, or a hard resin or a metal such as Al or Ti may be used. In order to enhance the matching of the elastic impedance with the object 1 to be diagnosed, an elastic material such as silicone rubber is desirable for the tip protective film.

[0191] According to the electronic stethoscope according to the fourth embodiment, as shown in FIG. 22B, a plurality of audible range sensor cells X each having a mechanical resonance frequency in the audible range mij By bringing the tip protective film of each of them into direct contact with the surface of the object 1 to be diagnosed, a characteristic audible range signal can be efficiently detected as a voltage signal. Further, when each of the plurality of audible range sensor cells X mij integrates an insulated gate type semiconductor as an internal structure, the detected characteristic audible range signal can be self-amplified by the electrostatic induction effect depending on the internal structure. As a result, even in an environment where the characteristic audible range signal serving as a sound source is weaker than the noise level, a high SN ratio can be achieved, and diagnosis with high objectivity and auscultation accuracy becomes possible.

[0192] (First Modification of the Fourth Embodiment) The housing 92e of the sound collecting unit of the electronic stethoscope according to the first modification of the fourth embodiment of the present invention is cylindrical, as shown in FIGS. 23A and 23B, and the upper part of the cross section cutting the center line of the circle looks like the structure of a high-floor building with a rectangular shape (FIG. 23B is a cross section viewed from the IIXIIIB-IIXIIIB direction of FIG. 23A). In the electronic stethoscope according to the fourth embodiment shown in FIGS. 22A and 22B, a rectangular semiconductor chip 41a in which the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 were monolithically integrated was used. For this reason, dead space was generated at the corners of the chip along the diagonal direction of the rectangle.

[0193] On the other hand, in the electronic stethoscope according to the first modification of the fourth embodiment of the present invention, as shown in FIGS. 23A and 23B, the audible range sensor cells X mp1 ~X mp6 and X mq1 are monolithically integrated hexagonal semiconductor chips 41b, which are housed inside the lower storage cavity located under the floor of the raised floor building formed by the housing 92e. Therefore, the dead space is reduced and further miniaturization is possible. As already described, the pattern areas of the audible range sensor cells X mp1 ~X mp6 and X mq1 shown in FIG. 23A respectively correspond to the planar patterns of the vibration cavities shown as the inner hexagons by hidden lines. That is, the seven inner hexagons shown in FIG. 23A correspond to the planar patterns of the seven drum-shaped detection parts, and the blank parts shown by the three white rectangles shown in FIG. 23B indicate the vibration cavities that become the drum-shaped detection parts. However, the three white rectangles shown in FIG. 23B are schematic representations, and each of the actual vibration cavities is a flat rectangle with a width of about 1.2 to 2.4 mm and a height of about 2 μm.

[0194] The outer skin of the housing 92e corresponds to the outer skin part of the raised floor building. FIG. 23B schematically shows the structure in which the upper rectangular part of the housing 92e has a flat plate-like part (plane part) on the upper surface, but the lower surface of the underfloor part has an open end. That is, the two spaces of the underfloor part of the raised floor building and the living space shown by the upper rectangle respectively become the storage cavities of the "lower storage cavity" and the "upper storage cavity". In the first modification of the fourth embodiment, the upper storage cavity of the living space constituting the raised floor building and the lower storage cavity of the underfloor part are collectively referred to as the "storage cavity". The placement of the semiconductor chip 41b inside the underfloor part of the raised floor building at a position almost closing the open end of the lower storage cavity of the underfloor part is a convenient expression for explaining that the underfloor part constitutes the lower storage cavity as an almost closed space.

[0195] In practice, the stethoscope according to the first modification of the fourth embodiment needs to be regularly disinfected, such as removing organic substances, each time the examination of one patient is completed. For this reason, the lower surface of the housing 92e is not an open end, but a seal surface that does not allow isopropyl alcohol or soapy water to permeate is formed using a plate-shaped seal layer that fills the open portion of the lower surface. However, the illustration is omitted in FIG. 23B. The plate-shaped seal layer whose illustration is omitted is combined with the lower surface and the outer surface of the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 are combined. When considering regular maintenance such as disinfection and cleaning in practical use, as shown in FIG. 16, the entire lower surface of the housing 92e may be covered with silicone rubber or the like.

[0196] In FIG. 23B, a structure in which the upper storage cavity and the lower storage cavity are divided by a uniform flat plate is illustrated, but it is only an illustration. In the stethoscope according to the first modification of the fourth embodiment, since the upper storage cavity and the lower storage cavity are spaces collectively called the "storage cavity", the flat plate that divides the upper storage cavity and the lower storage cavity may have slits or openings. Alternatively, a part of the storage cavity in the cross-sectional view shown in FIG. 22B may be divided by a flat plate that protrudes in the horizontal direction perpendicular to the side wall at the central part of the side wall of the downward U-shaped structure shown in FIG. 22A to form a middle second floor. The content disclosed in FIG. 23B is a convenient model representation for explaining that the lower storage cavity of the underfloor part of the high-rise building is configured as a substantially closed space by arranging the semiconductor chip 41b at a position substantially closing the open end of the underfloor part.

[0197] In the stethoscope according to the first modification of the fourth embodiment, a part of the lower surface of the space defined by the lower storage cavity of the underfloor part of the housing 92e shown in FIG. 23B becomes the "signal input surface" to which the characteristic audible range signal is input. Then, as shown in FIG. 23B, on the signal input surface of the housing 92e, a plurality of monolithically integrated audible range sensor cells X mijThe tip protection films 34 (see FIG. 5) at the top of each are exposed so as to contact the object to be diagnosed 1. For this reason, the tip protection films of the plurality of audible range sensor cells X mij can each contact the surface of the object to be diagnosed 1. In other words, in the stethoscope according to the first modification of the fourth embodiment, a plurality of audible range sensor cells X mij exposed so as to contact the object to be diagnosed 1 from the lower surface of the space defined in the lower storage cavity that is the underfloor portion of the housing 92e. The entire tip protection film of each of the plurality of audible range sensor cells X mij constitutes the signal input surface. The housing 92e of the sound collecting unit of the stethoscope according to the first modification of the fourth embodiment increases the reception sensitivity by detecting signals when the tip protection films of the plurality of audible range sensor cells X

[0198] contact the object to be diagnosed 1. As shown in FIG. 23B, the semiconductor chip 41b is flip-chip arranged so that the sensor array including the audible range sensor cells X mp1 ~X mp6 and X mq1 is located on the signal input surface side of the housing 92e. Then, characteristic audible range signals are input to the upper electrodes of the drum-shaped detection parts of the respective audible range sensor cells X mp1 ~X mp6 and X mq1 , and the upper electrodes vibrate to operate as drum-shaped (capacitive) audible range sensors. Each of the audible range sensor cells X mp1 ~X mp6 and X mq1 has a mechanical resonance frequency in the audible range, just like the stethoscope according to the first to fourth embodiments, and thus has high reception sensitivity (see FIG. 8, etc.). Although the specific structure of each of the audible range sensor cells X mp1 ~X mp6 and X mq1 is not shown, when an insulated gate type semiconductor is integrated as the internal structure, it is the same as the drum-shaped structure shown in FIG. 5 described above. In the structure shown in FIG. 5, it is preferable that the thickness of the tip protection film of the audible range sensor cell X mij is thin, as described with reference to FIG. 14.

[0199] As shown in FIG. 23A, a first audible range sensor cell X including a hexagonal drum-shaped detection portion having a first diagonal diameter is located at the center of a rectangular semiconductor chip 41b. mq1 The first audible range sensor cell X mq1 In the case of having an internal structure in which an insulated gate semiconductor is integrated, an example of the detailed structure of the planar pattern is the same as that of FIG. 4 already described. However, the divided structure into a central lower electrode and a peripheral lower electrode exemplified in FIG. 4 is not necessarily essential.

[0200] And, as shown in FIG. 23A, on the surface of the semiconductor chip 41b, around the first audible range sensor cell X mq1 Second audible range sensor cells X each having a second diagonal diameter longer than the first diagonal diameter, a third audible range sensor cell X mp1 , a fourth audible range sensor cell X mp2 , a fifth audible range sensor cell X mp3 , a sixth audible range sensor cell X mp4 , and a seventh audible range sensor cell X mp5 are respectively arranged at positions that divide the circumference into six equal parts and are monolithically integrated. The planar patterns of the second audible range sensor cell X mp6 , the third audible range sensor cell X mp1 , the fourth audible range sensor cell X mp2 , the fifth audible range sensor cell X mp3 , the sixth audible range sensor cell X mp4 , and the seventh audible range sensor cell X mp5 can also adopt a hexagonal shape as already exemplified in FIG. 4. mp6 The audible range sensor cell X

[0201] arranged in the center forms a hexagonal planar pattern having a first diagonal diameter, and each of the audible range sensor cells X mq1 arranged around forms a hexagonal planar pattern having the same second diagonal diameter and is an element of a monolithic integrated circuit. As shown in FIG. 23A, the housing 92e of the electronic stethoscope according to the first modification of the fourth embodiment includes a plurality of audible range sensor cells X mp1 ~X mp6 corresponding to a plurality of drum-shaped detection portions having different diagonal diameters. mijA semiconductor chip 41b monolithically integrated is disposed at the center of a housing 92e. And a first audible range sensor cell X including a drum-shaped detection part disposed at the center of the semiconductor chip 41b mq1 has a diagonal diameter smaller than that of the second to seventh audible range sensor cells X mq1 each having a drum-shaped detection part and disposed around the first audible range sensor cell X mp1 ~X mp6 . In the following description, unless otherwise necessary, the audible range sensor cells X mp1 ~X mp6 and X mq1 are not individually addressed, and the collective expression "audible range sensor cell X mij " is adopted for convenience.

[0202] As shown by the hidden lines in Fig. 23A, the audible range sensor cells X mp1 ~X mp6 with large diagonal diameter drum-shaped detection parts and the audible range sensor cell X mq1 with small diagonal diameter drum-shaped detection parts have different mechanical resonance frequencies in the monolithic integrated array. Therefore, the frequency band can be expanded so that the overall reception sensitivity of the semiconductor chip 41b is increased by intentionally shifting the mechanical resonance frequencies of the respective audible range sensor cells X mij in the monolithic integrated array composed of a plurality of drum-shaped detection parts from each other.

[0203] Note that, similar to the structures shown in Figs. 24A and 24B described later, the cross-sectional structure of the lower storage cavity, which is the floor part of the housing 92e, may be made into a closed rectangle, and may have a structure like a two-story building with two rectangles stacked. In Fig. 24B, it is schematically shown as having a structure like a two-story building with two rectangles stacked, where the lower rectangle forms the lower storage cavity and the upper rectangle forms the upper storage cavity. And in such a structure of the two-story building, seven hexagonal through-holes may be provided on the lower surface of the lower storage cavity corresponding to the seven hexagons in Fig. 24A. When the closed lower storage cavity is formed, seven audible range sensor cells X mijInsert each of them to form a plurality of audible range sensor cells X mij The tip protective film of each of mij may protrude or be flush with the diagnostic object 1 from the lower storage cavity.

[0204] Furthermore, as shown in Fig. 23B, on the semiconductor chip 41b, a pressure absorbing layer 44b made of an elastic body is laminated so as to be in contact with the ceiling surface of the lower storage cavity. When the housing 92e is pressed against the diagnostic object 1, the pressure absorbing layer 44b mp1 ~X mp6 and X mq1 absorbs the pressure applied to each of them, and functions so that the audible range sensor cells X mp1 ~X mp6 and X mq1 ~X mq5 are not damaged. In the upper storage cavity of the elevated building shown in Fig. 23B, a power circuit 96, a signal processing circuit 97, and a communication circuit 98 are housed, and together with the first semiconductor chip 41b housed in the lower storage cavity, they constitute a three-dimensional hybrid integrated circuit.

[0205] The power circuit 96 supplies the electrical energy required for the seven audible range sensor cells X mij integrated on the first semiconductor chip 41b, the signal processing circuit 97, and the communication circuit 98. The signal processing circuit 97 receives signals from the plurality of audible range sensor cells X mij and performs signal processing on the received signals. As shown in Fig. 23B, a ring-shaped antenna 99 is arranged in the upper storage cavity of the elevated building. The antenna 99 can adopt a dipole antenna, a spiral antenna, a planar antenna, etc. Although the illustration of connection wiring and the like is omitted, the input / output terminals of the communication circuit 98 are of course connected to the antenna 99.

[0206] Via the antenna 99, the communication circuit 98 can transmit the information signal - processed by the signal - processing circuit 97 to various information systems 3 in real - time, similar to that illustrated in FIG. 1A. For the communication between the housing 92e of the sound - collecting unit and the information system, wireless communication using electromagnetic waves in the 2.4 GHz band with an aerial power of 10 mW or less can be adopted. Through wireless communication via the antenna 99 and the like, the information signal - processed by the signal - processing circuit 97 is transmitted to the information system in real - time for easy visualization. Various biological information caused by the patient's heartbeat, respiration, blood flow, digestion, etc. can be accessed by the information system of the interested institution via wireless communication and the like.

[0207] The seven audible - range sensor cells X shown in FIG. 23A mij By detecting the characteristic audible - range signal such as the bio - audible - range signal, even in a small - sized housing 92e with a short outer diameter, the characteristic audible - range signal can be detected with sufficient signal strength. The audible - range sensor cell X mij By reducing the number of the audible - range sensor cells X to less than the seven shown in FIG. 23A, even if the outer diameter of the housing 92e of the sound - collecting unit is further reduced and miniaturized, auscultation can be performed well. The material of the housing 92e is not particularly limited. For example, soft plastics such as PVC or phthalate - based rubbers may be used, or hard resins or metals such as Al and Ti may also be used. To enhance the elastic impedance matching with the diagnostic object 1, an elastic material such as silicone rubber is desirable for the tip protective film.

[0208] According to the electronic stethoscope according to the first modification of the fourth embodiment, as shown in FIG. 23B, by directly contacting the tip protective films of a plurality of audible - range sensor cells X mij each having a mechanical resonance frequency in the audible range with the surface of the diagnostic object 1, the characteristic audible - range signal can be efficiently detected as a voltage signal by the audible - range sensor cells X mij inside the housing 92e of the sound - collecting unit. Furthermore, a plurality of audible - range sensor cells X mijWhen each of them has an internal structure that integrates an insulated-gate semiconductor, the detected characteristic audible range signal can be self-amplified by the electrostatic induction effect depending on the internal structure. As a result, even in an environment where the characteristic audible range signal serving as a sound source is weaker than the noise level, a high SN ratio can be achieved, enabling a diagnosis with high objectivity and auscultation accuracy.

[0209] (Second Modification Example of the Fourth Embodiment) As shown in FIGS. 24A and 24B, the housing 92f of the sound collecting part of the electronic stethoscope according to the second modification example of the fourth embodiment of the present invention has a pseudo-cylindrical shape in which the cross-sectional structure cutting the center line of the circle is similar to the structure of a two-story building with two rectangles stacked in two layers (FIG. 24B is a cross-section viewed from the IIXIVB-IIXIVB direction of FIG. 24A). The "pseudo-cylindrical shape" means that, as shown in FIG. 24B, the outer shape of the space on the lower side (first floor) of the two-story building is not a perfect rectangle, and the lower surface (bottom surface) is a concave surface and forms a concave polygon. The space surrounded by the lower concave polygon constitutes the lower storage cavity, and the rectangular space on the upper side (second floor) constitutes the upper storage cavity.

[0210] In the second modification example of the fourth embodiment, the upper storage cavity and the lower storage cavity constituting the two-story building are collectively referred to as the "storage cavity" as a whole. Actually, the plate-like part that divides the upper storage cavity and the lower storage cavity shown in FIG. 24B may have slits, openings, etc. The structure shown in FIG. 24B is only an example. For example, a flat plate protruding in the horizontal direction perpendicular to the side wall may be provided at the central part of the side wall of the downward U-shaped structure shown in FIG. 22A to divide a part of the storage cavity in the cross-sectional view shown in FIG. 24B to form a middle two-story structure. The outer skin of the housing 92f corresponds to the outer skin part of the two-story building. However, different from the structures shown in FIGS. 22A to 23B, the lower concave polygon-shaped lower surface of the first floor part has a shape in which the caldera-shaped concave surface is inverted up and down, forming a closed space for the lower storage cavity. Similar to the structures shown in FIGS. 22A to 23B, the upper surface of the upper rectangular part is a flat plate-like part (plane part).

[0211] In the electronic stethoscope according to the second modification of the fourth embodiment, a part of the caldera-shaped concave surface on the lower surface of the first-floor concave polygonal portion of the housing 92f shown in FIG. 24B becomes the "signal input surface" to which the characteristic audible range signal is input. FIG. 24B schematically shows a situation where, as in a conventional acoustic stethoscope, when the housing 92f is pressed against the human body as the object to be diagnosed 1, a part of the surface of the human body is recessed and comes into contact with the signal input surface that is a part of the caldera-shaped concave surface. In FIG. 24B, the portions protruding downward on both sides of the housing 92f, like the outer ring mountain of the caldera surrounding the signal input surface, correspond to the rim portion (diaphragm fixing ring) of the diaphragm-type acoustic stethoscope.

[0212] And, as shown in FIG. 24B, on the signal input surface of the housing 92f, a plurality of audible range sensor cells X mij exposed the tip protection film 34 (see FIG. 5) at the top of the upper electrode side, and the tip protection film of the audible range sensor cell X mij can directly contact the surface of the object to be diagnosed 1. In other words, from the lower surface of the concave surface presented by the first-floor concave polygon of the housing 92f, the entire tip protection film of each audible range sensor cell X mij exposed so as to contact the object to be diagnosed 1 constitutes the signal input surface. The housing 92f of the sound collecting part of the electronic stethoscope according to the second modification of the fourth embodiment enhances the reception sensitivity by directly detecting the characteristic audible range signal with the tip protection film of the audible range sensor cell X mij as the signal input surface.

[0213] As shown in FIG. 24A, on the semiconductor chip 41b, a sensor array including the audible range sensor cells X mp1 ~X mp6 and X mq1 is arranged in the same manner as in FIG. 23A. In FIG. 24A, the region between the second circle and the third circle from the outside is the slope portion presented by the outer ring mountain of the caldera. The signal input surface is defined inside the third circle from the outside in FIG. 24A. On the signal input surface defined inside the third circle, seven hexagonal through holes are provided as shown by the seven hexagons in FIG. 24A. And, as shown in FIG. 24B, the semiconductor chip 41b is such that the audible range sensor cell X mp1~X mp6 and X mq1 The flip chips are arranged such that the respective tops of ~X mp1 ~X mp6 and X mq1 are slidably inserted into seven hexagonal through-holes. However, for the audible range sensor cell X

[0214] As described for FIG. 23A, for the audible range sensor cell X shown in FIG. 24A mp1 ~X mp6 and X mq1 inside the area of the pattern, the planar pattern of the vibration cavity shown as the inner hexagon by hidden lines respectively corresponds to the planar pattern of the drum-shaped detection part. That is, the seven inner hexagons shown in FIG. 24A correspond to each of the planar patterns of the seven drum-shaped detection parts, and the blank parts shown by the three white rectangles shown in FIG. 24B indicate the vibration cavities that become the drum-shaped detection parts. However, the three white rectangles shown in FIG. 24B are schematic representations, and each of the actual vibration cavities is a flat square with a width of about 1.2 to 2.4 mm and a height of about 2 μm.

[0215] As shown in FIG. 24A, the housing 92f of the electronic stethoscope according to the second modification of the fourth embodiment arranges a semiconductor chip 41b in which a plurality of audible range sensor cells X mij corresponding to a plurality of drum-shaped detection parts with different diagonal diameters are monolithically integrated, at the central part of the housing 92f. And, as described for FIG. 23A, the diagonal diameter of the first audible range sensor cell X mq1 including the drum-shaped detection part arranged at the central part of the semiconductor chip 41b is mq1 smaller than the diagonal diameters of the second to seventh audible range sensor cells X mp1 ~X mp6 each having a drum-shaped detection part and arranged around the first audible range sensor cell X

[0216] As described with reference to FIG. 23A, the audible range sensor cell X, which is a large diagonal diameter drum-shaped detection unit as shown by the hidden line in FIG. 24A mp1 ~X mp6 and the audible range sensor cell X, which is a small diagonal diameter drum-shaped detection unit mq1 in the monolithic integrated array have different mechanical resonance frequencies from each other. Therefore, the frequency band can be expanded so that the overall reception sensitivity of the semiconductor chip 41b is increased by intentionally shifting the mechanical resonance frequencies of the respective audible range sensor cells in the monolithic integrated array composed of a plurality of drum-shaped detection units from each other.

[0217] Each of the corresponding seven audible range sensor cells X is slidably inserted into the seven through holes while maintaining the airtightness, whereby the tip protective film of each of the audible range sensor cells X mij comes into contact with the diagnostic object 1. As shown in FIG. 24A, the hexagonal outer shape of the semiconductor chip 41b in which the audible range sensor cells X mij ~X mp1 ~X mp6 and X mq1 are integrated is shown by the hidden line.

[0218] As shown in FIGS. 24A and 24B, the hexagonal semiconductor chip 41b in which the audible range sensor cells X mp1 ~X mp6 and X mq1 are integrated can be compactly housed inside the concave polygonal housing cavity on the lower side of the housing 92f. Therefore, according to the electronic stethoscope according to the second modification of the fourth embodiment, compared with the case where the rectangular semiconductor chip 41a shown in FIGS. 22A and 22B is used, the dead space is reduced and the size can be further reduced. The specific structures of the respective audible range sensor cells X mp1 ~X mp6 and X mq1 are not shown, but when they have an internal structure in which an insulated gate type semiconductor is integrated, they are the same as the drum-shaped structure shown in FIG. 5 already described.

[0219] And a plurality of audible range sensor cells X integrated monolithically mp1 ~X mp6 and X mq1 A characteristic audible range signal is input to the upper electrodes of the respective drum-shaped detection parts of and X through the tip protection film 34 and the upper electrode protection film 26, and the upper electrode 25c vibrates to operate as a drum-shaped (capacitive) MEMS sensor (see Fig. 5). Audible range sensor cell X mp1 ~X mp6 and X mq1 Each of and X has a mechanical resonance frequency in the audible range, similar to the electronic stethoscope according to the first to fourth embodiments, so the reception sensitivity is high (see Fig. 8 etc.). In the drum-shaped structure shown in Fig. 5, for the audible range sensor cell X mij it is better that the thickness of the tip protection film 34 is thin, as described with reference to Fig. 14. For the first audible range sensor cell X mij An example of the detailed structure of the planar pattern is the same as Fig. 4 already described when it has an internal structure incorporating an insulated gate type semiconductor integrated. However, the divided structure into a central lower electrode and a peripheral lower electrode illustrated in Fig. 4 is not necessarily essential.

[0220] And, as shown in Fig. 24B, on the semiconductor chip 41b, a pressure absorption layer 44b made of an elastic body is laminated so as to contact the ceiling surface of the lower accommodation cavity. The pressure absorption layer 44b, when the housing 92f is pressed against the diagnostic object 1, absorbs the pressure applied to each of the audible range sensor cells X mp1 ~X mp6 and X mq1 and functions so that the audible range sensor cells X mp1 ~X mp6 and X mq1 ~X mq5 are not damaged. In Fig. 24B, each of the seven corresponding audible range sensor cells X is slidably inserted into the seven through holes, so excessive pressure is applied to the audible range sensor cells X mij and X mp1 ~X mp6 and X mq1 ~X mq5When applied to, the pressure absorption layer 44b can absorb excessive pressure. Further, by forming the housing 92f of a flexible elastic body, excessive pressure is applied to the audible range sensor cells X mp1 ~X mp6 and X mq1 ~X mq5 When applied to, the pressure absorption layer 44b can absorb excessive pressure.

[0221] Furthermore, a power supply circuit 96, a signal processing circuit 97, and a communication circuit 98 are housed in the upper storage cavity of the two-story building, and together with the first semiconductor chip 41b housed in the lower storage cavity, they constitute a three-dimensional hybrid integrated circuit. The power supply circuit 96 supplies the electrical energy necessary for the seven audible range sensor cells X mij , the signal processing circuit 97, and the communication circuit 98. The signal processing circuit 97 receives signals from a plurality of audible range sensor cells X mij of different sizes, performs A / D conversion, and then executes signal processing such as smoothing of frequency characteristics and noise elimination using digital technology. As shown in FIG. 24B, a ring-shaped antenna 99 is arranged in the upper storage cavity of the two-story building. The antenna 99 can employ a dipole antenna, a spiral antenna, a planar antenna, or the like. Although illustration of connection wiring and the like is omitted, the input / output terminals of the communication circuit 98 are connected to the antenna 99.

[0222] Via the antenna 99, the communication circuit 98 can transmit the information signal-processed by the signal processing circuit 97 to various information systems 3 in real time, similar to that illustrated in FIG. 1A. Through wireless communication or the like via the antenna 99, the information signal-processed by the signal processing circuit 97 is transmitted to the information system in real time for easy visualization. Various biological information resulting from a patient's heartbeat, respiration, blood flow, digestion, etc. can be accessed by the information system of an interested institution via wireless communication or the like.

[0223] The seven audible range sensor cells X shown in FIG. 24A mijBy detecting the characteristic audible range signal, even in a small housing 92f with a short outer diameter, the characteristic audible range signal can be detected with sufficient signal strength. Audible range sensor cell X mij By reducing the number of the audible range sensor cells X shown in FIG. 24A to less than seven, even if the outer diameter of the housing 92f of the sound collecting section is further reduced and miniaturized, auscultation can be performed satisfactorily. The material of the housing 92f is not particularly limited. For example, even if it is a flexible and elastic material such as a soft plastic like PVC or a phthalate rubber or a silicone rubber that can be deformed by the pressure when the housing 92f is pressed against the object to be diagnosed, since the pressure absorbing layer 44b is provided, excessive pressure can be absorbed.

[0224] According to the electronic stethoscope according to the second modification of the fourth embodiment, a plurality of audible range sensor cells X each having a mechanical resonance frequency in the audible range mij By directly contacting the surface of the object to be diagnosed 1 as shown in FIG. 24B, the characteristic audible range signal can be efficiently detected as a voltage signal. Further, when each of the audible range sensor cells X mij has an internal structure in which an insulated gate type semiconductor is integrated, the detected characteristic audible range signal can be self-amplified by the electrostatic induction effect depending on the internal structure. As a result, according to the electronic stethoscope according to the second modification of the fourth embodiment, even in an environment where the characteristic audible range signal serving as the sound source is weaker than the noise level, a high SN ratio can be achieved, and diagnosis with high objectivity and auscultation accuracy becomes possible.

[0225] (Other embodiments) As described above, the present invention has been described according to the first to fourth embodiments, but it should not be understood that the discussions and drawings forming a part of this disclosure limit the present invention. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure. For example, in the electronic stethoscope according to the first to fourth embodiments, mainly the case where the planar pattern of the audible range sensor X ij or the audible range sensor cell X mw1 is a regular hexagon has been described mainly, but the audible range sensor X ij or the audible range sensor cell X mw1The planar pattern is not limited to a regular hexagon. For example, it may be a regular octagon, a regular dodecagon, a regular icosagon, or a circle. In particular, the wavelength λ in the audible range is very long, and compared to the size of λ / 4, the audible range sensor X ij or the audible range sensor cell X mw1 Since the diameter is sufficiently small, even for the shape of the planar pattern that affects distortion due to harmonics that need to be noted in the case of ultrasonic vibration, it does not pose a significant problem in the audible range.

[0226] In the paragraph about the electronic stethoscope according to the fourth embodiment, a layout combining a large-diameter audible range sensor cell X mv1 ~X mv4 and a small-diameter audible range sensor cell X mw1 ~X mw5 was described with reference to. The planar pattern and planar layout shown in FIG. 22A and the like are merely examples and are not limited to the planar pattern and planar layout shown in FIG. 22A and the like. The planar pattern of each of the audible range sensor cells X mv1 ~X mv4 and X mw1 ~X mw5 may be circular. However, regarding the planar layout in which the drum-shaped detection parts with a plurality of diameters are arranged inside the housing, as illustrated in FIG. 25(a), it should be noted that the diameter of the drum-shaped detection part located at the central part of the housing is smaller than at least one of the diameters of the drum-shaped detection parts outside the central part. Alternatively, as illustrated in FIG. 25(b), it should be noted that a planar layout is adopted in which no drum-shaped detection part is arranged at the position corresponding to the central part of the housing. When the planar layout illustrated in FIG. 25(a) and FIG. 25(b) is adopted, the pressure absorption layer 44a shown in FIG. 22B or the pressure absorption layers 44b shown in FIGS. 23B and 24B may be omitted.

[0227] In the planar layout shown in FIG. 25(a), a plurality of drum-shaped detection parts with different diagonal diameters are arranged inside the housing 92g of the electronic stethoscope, and at the central part of the housing 92g, there is a first audible range sensor cell X having a first inner diameter including the drum-shaped detection part mb1is arranged. In the schematic representation of the planar layout in Fig. 25(a), the illustration of the semiconductor chip is omitted, but the first audible range sensor cell X mb1 is monolithically integrated on the semiconductor chip together with other audible range sensor cells X ma1 ~X ma4 and X mb2 ~X mb5 As shown in Fig. 25(a), the first inner diameter of the first audible range sensor cell X mb1 is smaller than the second inner diameters of the second audible range sensor cell X mb1 monolithically integrated around the first audible range sensor cell X ma1 which has an outer drum-shaped detection part, the third audible range sensor cell X ma2 the fourth audible range sensor cell X ma3 and the fifth audible range sensor cell X ma4 Note that in the planar layout shown in Fig. 25(a), between the second audible range sensor cell X ma1 and the third audible range sensor cell X ma2 there is the sixth audible range sensor cell X mb2 which has the first inner diameter defining the size of the outer drum-shaped detection part and is monolithically integrated.

[0228] Similarly, between the third audible range sensor cell X ma2 and the fourth audible range sensor cell X ma3 there is the seventh audible range sensor cell X mb3 which has the first inner diameter defining the size of the outer drum-shaped detection part and is arranged, and between the fourth audible range sensor cell X ma3 and the fifth audible range sensor cell X ma4 there is the eighth audible range sensor cell X mb4 which has the first inner diameter of the outer drum-shaped detection part and is arranged. Also, between the fifth audible range sensor cell X ma4 and the second audible range sensor cell X ma1 there is the ninth audible range sensor cell X mb5is arranged. However, in the planar layout shown in Fig. 25(a), an important feature is that when a semiconductor chip in which drum-shaped detection parts of a plurality of diameters are monolithically integrated is arranged inside the housing 92g, the diameter of the drum-shaped detection part located at the center of the housing 92g is smaller than at least one of the diameters of the outer drum-shaped detection parts other than the central part.

[0229] The detection part array including a plurality of drum-shaped detection parts described in the first to fourth embodiments each has a structure of a thin drum-shaped vibration cavity. Therefore, if an excessive pressure is applied to the central part of the array, not only will the vibration cavity collapse and the electroacoustic conversion sensitivity be lost, but in the worst case, the vibration cavity will break. The planar layout shown in Fig. 25(a) is designed such that when the housing 92g is pressed against the surface of the diagnostic object 1, even when stress concentrates at the center of the semiconductor chip due to the macro stress distribution, the vibration cavity is less likely to be damaged because the diameter of the central audible range sensor cell is small. In the planar layouts illustrated in Figs. 22A, 23A, and 24A, when drum-shaped detection parts of a plurality of diameters are arranged inside the housings 92d, 92e, and 92f, the diameter of the drum-shaped detection part located at the center of the housings 92d, 92e, and 92f is designed to be smaller than at least one of the diameters of the outer drum-shaped detection parts other than the central part.

[0230] Note that the large-diameter drum-shaped detection part and the small-diameter drum-shaped detection part as shown in Fig. 25(a) have different mechanical resonance frequencies from each other. Therefore, by intentionally shifting the respective mechanical resonance frequencies in an array composed of a plurality of drum-shaped detection parts from each other, it is possible to simultaneously achieve the effect of expanding the frequency band of the electronic stethoscope so that the overall reception sensitivity is increased.

[0231] The planar layout shown in FIG. 25(b) also arranges a plurality of drum-shaped detection parts with different diagonal diameters inside the housing 92g. However, different from the planar layout shown in FIG. 25(a), it does not have a drum-shaped detection part with a small inner diameter (the first inner diameter) at the central part of the housing 92g, and there is a blank space. And around the blank space, there is a first audible range sensor cell X including a drum-shaped detection part with a large inner diameter (the second inner diameter). mc1 , a second audible range sensor cell X mc2 and a third audible range sensor cell X mc3 are arranged. Similar to FIG. 25(a), the illustration of the semiconductor chip is omitted in FIG. 25(b) as well. However, the audible range sensor cells X mc1 ~X mc3 are monolithically integrated on the semiconductor chip together with the audible range sensor cells X md1 ~X md3 . That is, between the first audible range sensor cell X mc1 and the second audible range sensor cell X mc2 , a fourth audible range sensor cell X having the first inner diameter of the small drum-shaped detection part md2 is monolithically integrated on the semiconductor chip.

[0232] Furthermore, between the second audible range sensor cell X mc2 and the third audible range sensor cell X mc3 , a fifth audible range sensor cell X having the first inner diameter of the small drum-shaped detection part md3 is arranged, and between the third audible range sensor cell X mc3 and the first audible range sensor cell X mc1 , a sixth audible range sensor cell X having the first inner diameter of the small drum-shaped detection part md1 is arranged. However, the important feature in the planar layout shown in FIG. 25(b) is that when a semiconductor chip on which drum-shaped detection parts with a plurality of diameters are monolithically integrated is arranged inside the housing 92g, it is set so as not to have a drum-shaped detection part located at the central part of the housing 92g.

[0233] The planar layout shown in Fig. 25(b) is structured such that when the housing 92g is pressed against the surface of the object to be diagnosed 1, even if stress concentrates at the center of the semiconductor chip due to the macro stress distribution, there is no audible range sensor cell at the center, so that breakage of the thin drum-shaped vibration cavity does not occur. While preventing breakage, the large-diameter drum-shaped detection part and the small-diameter drum-shaped detection part as shown in Fig. 25(b) have different mechanical resonance frequencies from each other. For this reason, by intentionally shifting the respective mechanical resonance frequencies in the array composed of a plurality of drum-shaped detection parts from each other, it is possible to simultaneously achieve the effect of expanding the frequency band of the electronic stethoscope so that the overall reception sensitivity is increased.

[0234] Also, in the description of the first to fourth embodiments already described, the case where the object to be diagnosed is a living body and the biological audible range signal is the object to be inspected as the characteristic audible range signal has been mainly described, but this is merely an example. The object to be diagnosed of the present invention is not limited to a living body, and may be a mechanical device or a structure such as concrete. When the mechanical device is the object to be diagnosed, vibrations due to defects or failures of the mechanical device become characteristic audible range signals. When concrete is the object to be diagnosed, vibrations caused by cracks or cavities contained in the concrete become characteristic audible range signals. When the object to be diagnosed of the present invention is a tree, when the electronic stethoscope of the present invention is applied to the bark, it is possible to hear the "pulsation" when water is sucked up in the trunk. The pulsation of the tree becomes a characteristic audible range signal that varies depending on the type of tree, the location where the electronic stethoscope is applied, and the health condition of the tree, such as "rustling", "popping", "groaning".

[0235] In the description of Fig. 19A and the like, the case where the flat surface of the tip protective film of the audible range sensor X is aligned with the bottom surface of the toroid formed by the housing 92c has been exemplified. However, the flat surface of the tip protective film of the audible range sensor X and the bottom surface of the toroid do not need to be exactly aligned on the outside, and the tip protective film of the audible range sensor X may be recessed by a very small depth of about 2 mm or less from the bottom surface of the toroid to form a concave portion. Also, the bottom surface of the toroid and the audible range sensor X ij The flat surface of the tip protective film of the audible range sensor X ij does not need to be exactly aligned on the outside with the bottom surface of the toroid, and the tip protective film of the audible range sensor X ij may be recessed by a very small depth of about 2 mm or less from the bottom surface of the toroid to form a concave portion. Also, the bottom surface of the toroid and the audible range sensor X ijThe flat surface of the tip protection film is not aligned with the bottom surface, and the audible range sensor X ij The tip protection film of may protrude from the bottom surface of the torus at a very slight height of about 2 mm or less to form a convex portion.

[0236] In the electronic stethoscope according to the third embodiment, the structure of the sound collecting part 9c in which the adsorption assisting part 95 is arranged as an adsorption pad at the center of the annular body as shown in FIG. 19B has been described, but this is merely an example. The means for fixing the sound collecting part 9c to the diagnostic object 1 is not limited to the adsorption pad, and the sound collecting part 9c may be fixed to the diagnostic object 1 by other means such as an adhesive tape. In this sense, the adsorption assisting part 95 of the electronic stethoscope according to the third embodiment is not an essential requirement, and even if the adsorption assisting part 95 is not provided at the center, the shape of the annular body shown in FIG. 18 etc. is not essential either.

[0237] In FIG. 5, each audible range sensor X v1 ~X v4 and X w1 ~X w5 The structure in which each central lower electrode 17c becomes a common region with the gate electrode of the corresponding insulated gate semiconductor element has been exemplarily described. However, the structure is not limited to that exemplified in FIG. 5. The technical idea of the audible range sensor with a built-in amplification element is, in principle, different from that of a normal insulated gate semiconductor element, and even in a structure without a gate electrode or a gate insulating film, an operation similar to that of a vacuum MOS transistor is possible. That is, if the upper electrode 25c vibrates due to the characteristic audible range signal between the upper electrode 25c set to the first potential and the channel formation region 14 set to the second potential, the capacitance between the channel formation region 14 and the upper electrode 25c changes, and charges are induced on the surface of the channel formation region 14 by the electrostatic induction effect. Therefore, the height of the potential barrier for electrons generated in the n-p-n hook structure between the first main electrode region 15b and the second main electrode region 15a can be controlled by the vibration of the upper electrode 25c due to the characteristic audible range signal.

[0238] That is, even in a structure without a gate electrode or a gate insulating film, the gate-substrate capacitance C is changed through the vibration of the upper electrode 25c due to the characteristic audible range signal gBChange it to cause a change in the current between the first main electrode region 15b and the second main electrode region 15a. As described above, the present invention is not limited to the descriptions of the first to fourth embodiments already described, and various modifications are possible, and it goes without saying that those are also included in the scope of the present invention. Therefore, the technical scope of the present invention is determined only by the invention-specific matters described in the scope of claims appropriate from the above description.

Explanation of Reference Numerals

[0239] 1…Object to be diagnosed, 3…Information system, 5…Display / operation unit, 6…Outer ear mounting part, 7…Acoustic tube, 9a, 9b, 9c, 9d, 9e…Sound collecting part, 11…Common substrate, 12…Gate insulating film (first gate insulating film), 13…Element isolation insulating film, 14…Channel formation region, 15a…Second main electrode region (drain region), 15b…First main electrode region (source region), 16…Second gate insulating film, 17c…Central lower electrode, 17o…Peripheral lower electrode, 19…Electric field strengthening layer, 20…Hollow forming insulating film, 23…Hollow vibrating membrane, 24a…Second contact plug, 24b…First contact plug, 25a…Second surface wiring layer, 25b…First surface wiring layer, 25c…Upper electrode, 26…Upper electrode protective film, 27…Liquid introduction hole, 28…Vibrating cavity, 31c…Rigidity strengthening lid part, 34…Tip protective film, 81 ij …Amplifier, 82…Main processing circuit, 89…Resistance adjustment circuit, 91…Buffer film holding part, 92a, 92b, 92c, 92d, 92e, 92f…Housing, 93…Buffer film, 95…Adsorption assisting part, 96…Power supply circuit, 97…Signal processing circuit, 98…Communication circuit, 99…Antenna, 701a…Ear tube, 702…Y-shaped tube, 703…Speaker, 704…Conductor.

Claims

1. A housing, An audible range sensor housed inside the storage cavity of the housing, having a mechanical resonance frequency in the audible range and having a drum-shaped detection part for detecting a characteristic audible range signal, An electronic stethoscope disposed inside the storage cavity and including a signal processing circuit that processes a signal output from the audible range sensor, The audible range sensor, When unloaded, an upper electrode parallel to the signal input surface and set to a first potential, A channel formation region made of a semiconductor region of a first conductivity type that is set to a second potential and is arranged parallel to the signal input surface at a position where the distance from the signal input surface is farther than the distance between the upper electrode and the signal input surface, First and second main electrode regions of a second conductivity type that are provided facing each other and spaced apart on the surface of the channel formation region, A cavity formation insulating film that surrounds the vibration cavity so as to provide the vibration cavity as a sealed region between the channel formation region and the upper electrode and supports the periphery of the upper electrode, An electronic stethoscope comprising: detecting displacement of the upper electrode due to the characteristic audible range signal as a change in current flowing between the first and second main electrode regions.

2. The electronic stethoscope according to claim 1, wherein the audible range sensor detects a characteristic audible range signal from the diagnostic object without interposing an air layer between the audible range sensor and the diagnostic object.

3. The audible range sensor, A gate insulating film provided on the first and second main electrode regions and on the channel formation region sandwiched between the first and second main electrode regions, A central lower electrode made of a conductor layer provided on the gate insulating film above the channel formation region sandwiched between the first and second main electrode regions so as to be at least in a quasi-floating state, The electronic stethoscope according to claim 2, further comprising:

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