Electronic auscultation device and diaphragm displacement detector

Abstract

To accurately detect displacement of biological surface.SOLUTION: An electronic auscultation device comprises: a diaphragm 206 that is disposed such that an outer surface 206a comes into contact with a subject living body, and has a light reflection surface on a side opposite to the outer surface; a light source that emits light toward the light reflection surface of the diaphragm; and a light receiving part that receives light emitted by the light source and reflected at the light reflection surface, and outputs a signal corresponding to the received light quantity. The diaphragm further includes a low-reflection surface 1702 positioned around the light reflection surface 1701, the low-reflection surface having a lower reflectance than the light reflection surface.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The present invention relates to an electronic auscultation device and a diaphragm displacement detection device. [Background technology]

[0002] Electronic auscultation devices for acquiring vibration sounds based on the displacement of the surface of a living body are becoming popular. Patent Document 1 proposes an electronic auscultation device that collects biological sounds using a capacitive microphone. Patent Document 2 proposes an auscultation device that uses a vibration sensor in the acquisition unit that acquires biological sounds. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-119446 [Patent Document 2] JP 2017-47095 A Summary of the Invention [Problem to be solved by the invention]

[0004] With a microphone small enough to fit into an auscultation device like the one in Patent Document 1, it is difficult to accurately detect low-frequency vibrations around 10 Hz emitted by the body. When detecting pressure changes based on biological surface displacement using an acceleration sensor or piezoelectric element as in Patent Document 2, it is necessary to apply a certain amount of pressure to the biological surface. As a result, the amount of biological surface displacement decreases, and the S / N ratio deteriorates. One aspect of the present invention aims to provide a technology for accurately detecting biological surface displacement. [Means for solving the problem]

[0005] According to some embodiments, there is provided an electronic auscultation device comprising: a diaphragm arranged so that its outer surface is in contact with a living subject's body and having a light-reflecting surface on the opposite side to the outer surface; a light source that irradiates light toward the light-reflecting surface of the diaphragm; and a light-receiving unit that receives the light irradiated by the light source and reflected by the light-reflecting surface and outputs a signal corresponding to the amount of light received, wherein the diaphragm further has a low-reflecting surface around the light-reflecting surface that has a reflectivity lower than that of the light-reflecting surface. [Effects of the Invention]

[0006] According to the above embodiment, the displacement of the living body surface can be detected with high accuracy. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an example of the appearance of an electronic auscultation device according to a first embodiment. [Figure 2] 1 is a schematic diagram illustrating a configuration example of a chest piece according to a first embodiment. [Figure 3] 5A to 5C are schematic diagrams illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 4] 5A to 5C are schematic diagrams illustrating an example of movement of reflected light in the first embodiment. [Figure 5] FIG. 4 is a diagram illustrating the relationship between the displacement amount and the displacement signal according to the first embodiment. [Figure 6] 1 is a block diagram illustrating an example of the configuration of an electronic auscultation device according to a first embodiment. [Figure 7] 5A to 5C are schematic diagrams illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 8] 5A and 5B are schematic diagrams illustrating an example of change in the light receiving range according to the first embodiment. [Figure 9] FIG. 10 is a schematic diagram illustrating a modified example of the chestpiece of the first embodiment. [Figure 10] FIG. 10 is a block diagram illustrating an example of the configuration of an electronic auscultation device according to a second embodiment. [Figure 11] FIG. 10 is a schematic diagram illustrating a configuration example of a chest piece according to a second embodiment. [Figure 12]FIG. 10 is a schematic diagram illustrating a configuration example of a chest piece according to a second embodiment. [Figure 13] FIG. 10 is a schematic diagram illustrating a configuration example of a chest piece according to a second embodiment. [Figure 14] FIG. 10 is a schematic diagram illustrating a modified example of the chestpiece of the second embodiment. [Figure 15] FIG. 10 is a schematic diagram illustrating a modified example of the chestpiece of the second embodiment. [Figure 16] FIG. 10 is a schematic diagram illustrating a modified example of the chestpiece of the second embodiment. [Figure 17] FIG. 10 is a schematic diagram illustrating the light reflecting surface of the chest piece of the second embodiment. [Figure 18] 5A and 5B are schematic diagrams illustrating an example of the configuration of a holding member according to a second embodiment. [Figure 19] 5A to 5C are diagrams illustrating the influence of the reflectance of the low-reflection surface according to the first embodiment. [Figure 20] 5A and 5B are diagrams for explaining a state in which the reflectance of the low-reflection surface is high in the first embodiment. [Figure 21] 5A and 5B are diagrams for explaining a state in which the reflectance of the low-reflection surface of the first embodiment is low. [Figure 22] FIG. 3 is a schematic diagram illustrating the position of a reflecting member in the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0009] First Embodiment [Appearance of the electronic auscultation device in the first embodiment] The appearance of the electronic auscultation device 100 according to the first embodiment will be described with reference to FIGS. 1 to 9. In the following drawings, a coordinate system CS, which is a three-dimensional Cartesian coordinate system having an x-axis, a y-axis, and a z-axis, may be used to explain directions. In these descriptions, the positive direction of the z-axis may be referred to as the upper side, and the negative direction of the z-axis may be referred to as the lower side. FIG. 1(a) shows the appearance of the electronic auscultation device 100 when viewed from one direction, and FIG. 1(b) shows the appearance of the electronic auscultation device 100 when viewed from another direction. The electronic auscultation device 100 may be used, for example, for diagnosing a living organism. The living organism may be a human or a non-human animal.

[0010] The electronic auscultation device 100 includes a chestpiece 110 and a grip portion 120. The chestpiece 110 is the part that comes into contact with a living body during diagnosis using the electronic auscultation device 100. Because the chestpiece 110 detects displacement of the living body surface via a diaphragm, it is also called a displacement detection device or a diaphragm displacement detection device. Furthermore, because the chestpiece 110 is used to detect vibrations on the living body surface, it is sometimes called a living body vibration detection device.

[0011] The gripping portion 120 is a portion that is gripped by a user (e.g., a doctor, nurse, or public health nurse) of the electronic auscultation device 100 when bringing the diaphragm 206 into close contact with the surface of a living body. Hereinafter, the user of the electronic auscultation device 100 will be simply referred to as the user. As shown in FIG. 1, the gripping portion 120 has a rod-like shape, and the chestpiece 110 is attached to one end (the negative x-axis direction in FIG. 1). The gripping portion 120 may also be called a handle, a grip, a handle, or the like. In this embodiment, the gripping portion 120 and the chestpiece 110 are configured to be able to swing relative to each other. However, the present invention is not limited to this, and the chestpiece 110 may be fixed to the gripping portion 120.

[0012] The grip part 120 has a battery and a circuit board inside a housing 121. The battery stores operating power for the electronic auscultation device 100. The circuit board has circuit elements for controlling the operation of the electronic auscultation device 100. The grip part 120 has a housing 121. The grip part 120 has a display unit 122, an operation unit 123, a power switch 124, and a connector 125 on the outer surface of the housing 121.

[0013] The display unit 122 displays the status of the electronic auscultation device 100. For example, the display unit 122 may include multiple indicators (four indicators in the example of FIG. 1(a)). Each indicator is configured with a light-emitting diode (LED). The multiple indicators include an indicator that indicates whether the power of the electronic auscultation device 100 is on or off. The multiple indicators also include an indicator that indicates the current operating mode of the electronic auscultation device 100. The multiple indicators also include an indicator that indicates whether the electronic auscultation device 100 is wirelessly connected to an external device. The multiple indicators also include an indicator that indicates whether the chestpiece 110 is pressed against a living body surface. As shown in FIG. 1(a), the display unit 122 is located on the outer surface of the housing 121, on the side opposite the chestpiece 110, near the chestpiece 110, which is one end in the x-axis direction. "Near the chestpiece 110" means that the display unit 122 is closer to the chestpiece 110 than the center of the grip portion 120. With this arrangement, when a user grips the other end of the grip portion 120 in the x-axis direction, the display portion arranged at one end in the x-axis direction will not be hidden by the user's hand. As a result, the user can easily see the display portion 122. Note that the display portion 122 does not need to include all of the indicators described above, and the status of the electronic auscultation device 100 may be displayed by a liquid crystal panel or an electrostatic panel instead of or in addition to multiple indicators.

[0014] The operation unit 123 accepts operations from the user. In this embodiment, the operation unit 123 includes multiple physical buttons (three buttons in the example of FIG. 1(a)). Specifically, the operation unit 123 includes volume adjustment buttons (volume up button 123a and volume down button 123b) for adjusting the volume of the output sound. When the volume adjustment button is pressed, the electronic auscultation device 100 adjusts the gain of the signal output from the light receiving element 204 and adjusts the volume of the sound output through the earphone. The operation unit 123 also includes a mode switching button 123c for switching the operation mode of the electronic auscultation device 100. When the mode switching button 123c is pressed, the operation mode is switched as described below. The operation unit 123 may include a touch panel instead of multiple physical buttons. The display unit 122 and the operation unit 123 may be integrated into a touch screen.

[0015] Like the display unit 122, the operation unit 123 is arranged on the outer surface of the housing 121 opposite the chestpiece 110, near the chestpiece 110, at one end in the x-axis direction. With this arrangement, the user can operate the operation unit 123 (for example, with their thumb) while holding the grip unit 120 while using the electronic auscultation device 100. Furthermore, the display unit 122 is arranged at a position farther away from the center of the grip unit 120 in the x-axis direction than the operation unit 123. With this arrangement, the user can maintain visibility of the display unit 122 even when operating the operation unit 123 while using the electronic auscultation device 100.

[0016] The power switch 124 is a switch that switches the power of the electronic auscultation device 100 on and off. The connector 125 is a connector for receiving a cable or a connector of an external device. Power is supplied from the external device to the battery included in the grip portion 120 through the connector 125. The power switch 124 may be provided on the chestpiece 110 instead of the grip portion 120. The connector 125 may be provided on the chestpiece 110 instead of the grip portion 120. Furthermore, the electronic auscultation device 100 does not have to include the connector 125. In this case, the electronic auscultation device 100 may have a wireless charging function or may be configured so that the battery is replaceable.

[0017] The electronic stethoscope device 100 in this embodiment includes both the chestpiece 110 and the grip portion 120, but may alternatively include only the chestpiece 110 and not the grip portion 120.

[0018] [Chestpiece configuration of the electronic stethoscope device in the first embodiment] An example configuration of chestpiece 110 will be described with reference to Fig. 2. The upper side of Fig. 2 shows a cross-sectional view of chestpiece 110, and the lower side of Fig. 2 shows a plan view of chestpiece 110. In the plan view, only light-emitting circuit board 203, light-receiving circuit board 205, diaphragm 206, and reflecting member 207 are shown to clarify the positional relationship of the components.

[0019] Chestpiece 110 has a holding member 201, a light-emitting element 202, a light-emitting circuit board 203, a light-receiving element 204, a light-receiving circuit board 205, a diaphragm 206, a reflecting member 207, and a housing 208. Note that the components of chestpiece 110 described here are examples, and in addition to the components shown in Fig. 2, chestpiece 110 may also have a circuit board on which circuit elements for controlling the operation of chestpiece 110 are mounted.

[0020] The light-emitting element 202 is a light source that emits light. Power is supplied to the light-emitting element 202 from a power source external to the chestpiece 110 (for example, a battery in the grip portion 120). In this embodiment, the light-emitting element 202 is a light-emitting diode (LED), but a laser diode may also be used. Note that power may also be supplied to the light-emitting element 202 from a battery (not shown) installed in the chestpiece 110.

[0021] The light emitting element 202 is mounted on a light emitting circuit board 203. On the light emitting circuit board 203, for example, a peripheral circuit for regulating the light emission amount of the light emitting element 202 and a power supply terminal for receiving power from a power source external to the chest piece 110 are mounted. The light emitting circuit board 203 may be a printed wiring board such as a flexible circuit board, a paper phenolic board, a glass epoxy board, or another board. The light emitting circuit board 203 including the light emitting element 202 functions as a light emitting unit.

[0022] The light receiving element 204 generates an electrical signal based on the amount of light received using power supplied from a power source external to the chestpiece 110 (e.g., a battery in the grip portion 120). The power supplied to the light receiving element 204 may be supplied from a power source external to the chestpiece 110 (e.g., a battery in the grip portion 120) or from a battery (not shown) mounted in the chestpiece 110. The light receiving element 204 may be, for example, a phototransistor or a complementary metal-oxide semiconductor (CMOS) sensor. In this embodiment, the number of light receiving element 204 is one, but the present invention is not limited to this. A line sensor or an area sensor may be configured using multiple light receiving elements 204.

[0023] The light receiving element 204 is mounted on a light receiving circuit board 205. In addition to the light receiving element 204, other components may be mounted on the light receiving circuit board 205. For example, the light receiving circuit board 205 may be mounted with a peripheral circuit for reading out a signal from the light receiving element 204, a signal terminal for outputting a signal to an external device of the chest piece 110, and a power terminal for receiving power from an external power source of the chest piece 110. The light receiving circuit board 205 may be a printed wiring board such as a flexible circuit board, a paper phenolic board, a glass epoxy board, or other board. The light receiving circuit board 205 including the light receiving element 204 functions as a light receiving unit.

[0024] The holding member 201 holds the light-emitting circuit board 203 and the light-receiving circuit board 205. The light-emitting circuit board 203 and the light-receiving circuit board 205 are fixed to the holding member 201. These boards may be fixed to the holding member 201 using an adhesive or using fastening members such as screws.

[0025] The holding member 201 further holds a diaphragm 206. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 is a membrane having a circular outer edge in a plan view. The diaphragm 206 is arranged to contact a biological surface. The diaphragm 206 forms part of the outer surface of the chestpiece 110. The diaphragm 206 has an outer surface 206a that is arranged to contact a biological surface when the electronic stethoscope device 100 is in use, and an inner surface 206b that is opposite the outer surface 206a.

[0026] The diaphragm 206 has a fixed portion 206c fixed to the holding member 201. The diaphragm 206 may be fixed to the holding member 201 using an adhesive. The fixed portion 206c is located on the outer periphery of the diaphragm 206. The inner periphery of the diaphragm 206 (i.e., the portion inside the fixed portion 206c) is not fixed to the holding member 201. Therefore, the diaphragm 206 can vibrate in the z-axis direction with the fixed portion 206c as a node. Specifically, when the chestpiece 110 is in use, the diaphragm 206 vibrates with the fixed portion 206c as a node in response to displacement of the surface of the living body. In this vibration, the center 206e of the diaphragm 206 becomes an antinode. The diaphragm 206 functions as a vibrating unit.

[0027] The reflecting member 207 is a reflecting portion that reflects light emitted from the light-emitting element 202. The reflecting member 207 is adhered to the inner surface 206b of the diaphragm 206, and thus moves in the z-axis direction in response to the vibration of the diaphragm 206, which is in close contact with the surface of a living body. The reflecting member 207 has a circular outer edge in a plan view. For example, the reflecting member 207 may have a diameter of 15 mm to 20 mm. Alternatively, the outer edge of the reflecting member 207 may have another shape. The reflecting member 207 is positioned to cover a region 206d including the center 206e of the diaphragm 206. Since the displacement of the diaphragm 206 changes most significantly at the center 206e, the displacement of the diaphragm 206 can be detected with high sensitivity by reflecting the light from the light-emitting element 202 in the region including the center 206e. Note that, although the reflecting member 207 is positioned to cover the center 206e in this embodiment, it may also be positioned to cover a region of the diaphragm 206 that does not include the center 206e. The reflecting member 207 is made of, for example, an aluminum vapor deposition film. Details of the reflecting member 207 will be described later.

[0028] The light emitting element 202 emits light toward the reflecting member 207, and the upper surface of the reflecting member 207 reflects the light emitted by the light emitting element 202. That is, the upper surface of the reflecting member 207 functions as a light reflecting surface. In the following description, the reflection of light on the upper surface of the reflecting member 207 (that is, the light reflecting surface) will simply be referred to as light being reflected by the reflecting member 207. The reflecting member 207 specularly reflects (in other words, specularly reflects) the light emitted by the light emitting element 202. In the following description, the light traveling from the light emitting element 202 toward the reflecting member 207 will be referred to as incident light 211, and the light after the incident light 211 is reflected will be referred to as reflected light 212.

[0029] In this embodiment, the reflecting member 207 is a separate member from the diaphragm 206. However, the reflecting member 207 may be a coating layer applied to the diaphragm 206. The reflecting member 207 may also be a sticker or the like attached to the diaphragm 206. The reflecting member 207 may be configured as the same member as the diaphragm 206, and at least a part of the inner surface 206b of the diaphragm 206 may also serve as a reflecting portion. For example, the entire inner surface 206b of the diaphragm 206 may have a high reflectivity that can reflect light to an extent that can be detected by the light receiving element 204. Alternatively, only a region of the inner surface 206b of the diaphragm 206 that is reached by light irradiated by the light emitting element 202 may have such a high reflectivity.

[0030] The light-emitting element 202 is disposed so as to irradiate light onto a region 207a of the reflecting member 207 that includes a portion covering the center 206e of the diaphragm 206 when the diaphragm 206 is not in contact with the surface of the living body. When the diaphragm 206 is not in contact with the surface of the living body, the diaphragm 206 is flat. The light-emitting element 202 irradiates light onto a specific region (e.g., region 207a) of the reflecting member 207. As described above, in this embodiment, an LED that emits diffused light is used as the light-emitting element 202. Therefore, the chestpiece 110 has an aperture 209 that limits the range of light irradiated from the light-emitting element 202. The aperture 209 allows only a portion of the light emitted by the light-emitting element 202 to be irradiated onto the reflecting member 207. In the example of FIG. 2, an opening formed in the holding member 201 corresponds to the aperture 209. In the present embodiment, a component that emits diffused light has been described as an example of the light-emitting element 202, but instead, a component that emits linear light may be used as the light-emitting element 202, and the linear light may be irradiated toward the region 207a. Note that the diaphragm 209 may also be used when the light-emitting element 202 is a component that emits linear light.

[0031] The light receiving element 204 is positioned to receive the reflected light 212. Specifically, the light receiving element 204 is positioned at a position where the amount of the received reflected light 212 changes due to vibration of the diaphragm 206 in the z-axis direction. The light receiving element 204 is positioned so that when the diaphragm 206 is not in contact with the surface of the living body (i.e., when the diaphragm 206 is flat), it receives more of the reflected light 212 than when the diaphragm 206 is vibrating. That is, the light receiving element 204 outputs an electrical signal corresponding to the amount of reflected light 212 it receives, and the amount of displacement of the diaphragm 206 can be determined. The principle behind this is described below. The chestpiece 110 has an aperture 210 that limits the range of light incident on the light receiving element 204. The aperture 210 prevents diffusely reflected light from entering the light receiving element 204, allowing only at least a portion of the light from the reflecting member 207 (i.e., the primarily reflected light) to reach the light receiving element 204. 2, an opening formed in the holding member 201 functions as the diaphragm 210. Alternatively, the diaphragm 210 may be formed in other ways.

[0032] A housing 208 is attached to the outer circumferential upper surface of the holding member 201. The housing 208 covers the light-emitting circuit board 203 and the light-receiving circuit board 205 and prevents ambient sound from entering the housing 208. The outer edges of the diaphragm 206, the holding member 201, and the housing 208 may coincide with one another in a plan view with respect to the outer surface 206a of the diaphragm 206. In this embodiment, the housing 208 is made of stainless steel.

[0033] By fixing the diaphragm 206 to the holding member 201, an internal space 213 is formed that is surrounded by the diaphragm 206 and the holding member 201. The internal space 213 is sealed in order to prevent the light receiving element 204 from receiving any light other than that emitted by the light emitting element 202. Furthermore, the diaphragm 206 has a light-blocking property in order to prevent the light receiving element 204 from receiving any light other than that emitted by the light emitting element 202. Alternatively or in addition to this, the diaphragm 206 may be covered with a light-blocking film. Similarly, the holding member 201 may have a light-blocking property or may be covered with a light-blocking film.

[0034] [Example of operation of the electronic auscultation device in the first embodiment] An example of the operation of the chestpiece 110 of the electronic auscultation device 100 in the first embodiment will be described with reference to FIG. 3. As shown in FIGS. 3(a) and 3(b), the chestpiece 110 is used in contact with a biological surface 300. That is, during use, the outer surface 206a of the diaphragm 206 of the chestpiece 110 is in close contact with the biological surface 300. This causes the biological surface 300, the diaphragm 206, and the reflecting member 207 to vibrate together. The chestpiece 110 detects the displacement of the upper surface of the reflecting member 207 in the z-axis direction as the displacement of the biological surface 300 in the z-axis direction. The displacement of the biological surface 300 occurs in response to physical movements, such as heartbeat and breathing, of the person who owns the biological surface 300.

[0035] FIG. 3(a) shows a cross-sectional view of the chestpiece 110 when the diaphragm 206 is flat. As described above, the light-emitting element 202 and the light-receiving element 204 are positioned so that when the diaphragm 206 is flat, the light-receiving element 204 receives more reflected light 212 than when the diaphragm 206 is vibrating. The light-receiving element 204 amplifies and outputs a photocurrent corresponding to the amount of light received. The peripheral circuit of the light-receiving circuit board 205 converts the photocurrent output from the light-receiving element 204 into a voltage, obtains an output value, and generates the output value as a displacement signal. The displacement signal is output to an external device. In this embodiment, the displacement signal refers to the output value of the light-receiving element 204, which reflects the state and deformation of the diaphragm 206 at any given time.

[0036] FIG. 3(b) shows a cross-sectional view of the chestpiece 110 when the biological surface 300 is displaced upward. The distance between the light-emitting element 202 and the upper surface of the reflecting member 207 is denoted by d1. As the biological surface 300 is displaced upward, the distance d1 decreases. Accordingly, the region 207a of the reflecting member 207 that is irradiated with the incident light 211 moves closer to the light-emitting element 202, and the reflected light 212 also moves closer to the light-emitting element 202. This reduces the amount of reflected light 212 that reaches the light-receiving element 204, reducing the value of the displacement signal generated by the light-receiving circuit board 205. In the state shown in FIG. 3(b), none of the reflected light 212 reaches the light-receiving element 204, so the value of the displacement signal is ideally zero.

[0037] Thus, in the chestpiece 110, the light-emitting element 202 and the light-receiving element 204 are arranged so that the amount of light reaching the light-receiving element 204 changes in response to the movement of the biological surface 300, the diaphragm 206, and the reflecting member 207. Because the reflecting member 207 displaces in conjunction with the displacement of the biological surface 300, the displacement signal generated by the light-receiving circuit board 205 represents the displacement of the biological surface 300.

[0038] [Relationship between the amount of displacement of the diaphragm and the amount of displacement of the reflected light in the electronic auscultation device according to the first embodiment] 4, the relationship between the displacement amount of the biological surface 300, the angle of incidence of the incident light 211, and the displacement amount of the reflected light 212 will be described. Position 401 indicates the reference position of the top surface of the reflecting member 207. In this embodiment, the top surface of the reflecting member 207 when the diaphragm 206 is flat is taken as the reference position. Position 402 indicates the position where the top surface of the reflecting member 207 is displaced upward from position 401 by a displacement amount d2. Because the displacement amount d2 of the reflecting member 207 is minute, the top surface of the reflecting member 207 is considered to be flat even when it is at position 402.

[0039] In FIG. 4, optical axis 403 indicates the optical axis of incident light 211. The angle of incidence of light emitted by light emitting element 202 (i.e., incident light 211) on reflecting member 207 is represented by θ. The angle of incidence θ of incident light 211 is defined by the angle between optical axis 403 of incident light 211 and the normal to the top surface of reflecting member 207. The optical axis of reflected light 212 when the top surface of reflecting member 207 is at position 401 is represented by optical axis 404. The optical axis of reflected light 212 when the top surface of reflecting member 207 is at position 402 is represented by optical axis 405. Since incident light 211 is specularly reflected by the top surface of reflecting member 207, the reflection angle of reflected light 212 is also θ. The amount of displacement from optical axis 404 to optical axis 405 is represented by d3. In this case, d3=2×d2×sinθ …(Equation 1) The following relationship holds.

[0040] [Relationship between the displacement amount of the living body surface and the displacement signal in the electronic auscultation device according to the first embodiment] The relationship between the displacement amount of the biological surface 300 and the displacement signal will be described with reference to Fig. 5. A graph 500 in Fig. 5 shows the relationship between the displacement amount of the biological surface 300 and the displacement signal. The horizontal axis of the graph 500 represents the displacement amount of the biological surface 300, and represents the displacement signal generated by the light receiving circuit board 205.

[0041] As described above, the displacement of the biological surface 300 is equal to the displacement d2 of the upper surface of the reflecting member 207. As shown in Fig. 3, as the displacement d3 of the reflected light 212 increases, the light that reaches the light receiving element 204 of the reflected light 212 decreases linearly. Therefore, when the value of the displacement signal is represented as Sd, Sd=Vmax-k×d3…(Formula 2) Here, Vmax is the value of the displacement signal when the displacement amount d3 of the reflected light 212 is zero, and k is a proportionality coefficient determined by the amplification factor of the light receiving circuit board 205. By substituting Equation 1 into Equation 2, Sd=Vmax-2k×d2×sinθ…(Formula 3) is obtained. Therefore, as shown by graph 500, the displacement signal Sd decreases linearly as the displacement amount d2 of the biological surface 300 increases. The displacement amount at which the displacement signal Sd becomes zero is represented as dmax. When the displacement amount exceeds dmax, the reflected light 212 no longer reaches the light receiving element 204, so even if the displacement amount d2 increases, the displacement signal Sd remains zero. Therefore, the proportionality coefficient k and the incident angle θ are set so that the displacement amount d2 is in the range between 0 and dmax within the range in which the diaphragm 206 is expected to vibrate (this is referred to as the operating range of the diaphragm 206). As shown in graph 500, the light emitting element 202 and the light receiving element 204 are arranged so that the amount of light reaching the light receiving element 204 changes monotonically in response to movement of the reflecting member 207 in one direction within the operating range of the diaphragm 206.

[0042] In Equation 3, the coefficient of d2, 2k × sin θ, represents the sensitivity of chestpiece 110. The incident angle θ can take a value greater than 0 degrees and less than 90 degrees. The larger θ, the higher the sensitivity of chestpiece 110. Therefore, it is preferable to configure chestpiece 110 so that the incident angle θ is 45 degrees or greater.

[0043] In this embodiment, the light emitting element 202 and the light receiving element 204 are arranged so that all of the reflected light 212 reaches the light receiving element 204 (i.e., so that the displacement signal becomes Vmax) when the diaphragm 206 is flat. Alternatively, the light emitting element 202 and the light receiving element 204 may be arranged so that all of the reflected light 212 reaches the light receiving element 204 when the diaphragm 206 is in a position displaced downward.

[0044] The chestpiece 110 according to the above embodiment can accurately detect the displacement of the biological surface 300. Specifically, in the above-described chestpiece 110, a displacement signal is generated based on the displacement amount d2 of the reflective film. Therefore, regardless of the frequency at which the biological surface 300 vibrates, the displacement of the biological surface 300 can be accurately detected. For example, the displacement of the biological surface 300 due to low-frequency vibrations of about 10 Hz can also be accurately detected. Such low-frequency vibrations can be included in the displacement sound of the biological surface (e.g., heart sounds) caused by the biological surface being displaced by vibrations propagated from inside the body due to heartbeats. Furthermore, in the chestpiece 110, the displacement signal does not change unless the diaphragm 206 is displaced. Therefore, ambient sounds around the chestpiece 110 and vibrations and accelerations due to the movement of the chestpiece 110 are not detected as noise, resulting in output characteristics with a high S / N ratio.

[0045] [Hardware configuration of the electronic auscultation device in the first embodiment] Referring to FIG. 6, an example of the hardware configuration of the electronic auscultation device 100 in the first embodiment will be described. The electronic auscultation device 100 includes the chestpiece 110 and a sound output unit 610. The sound output unit 610 is implemented by a plurality of circuit elements mounted on a circuit board included in the grip unit 120. The sound output unit 610 outputs a sound signal based on a displacement signal generated by the chestpiece 110. The sound signal output by the sound output unit 610 represents the body sounds of a living body (e.g., a human) having a body surface 300. The sound signal is transmitted to a sound output device 620 such as earphones or headphones. The sound signal is also transmitted to a computer 630 (e.g., a personal computer, smartphone, tablet, etc.) simultaneously with being transmitted to the sound output device 620. A user such as a doctor, nurse, or public health nurse can listen to the body sounds represented by the digitally converted sound signals using the sound output device 620 or the computer 630.

[0046] The sound output unit 610 has the components shown in FIG.

[0047] The sound output device 620 is a wired or wireless earphone or headphone. Since the sound output unit 610 conforms to the earphone or headphone, it can output a sound signal via both wireless and wired communication. The following describes the process by which the sound output device 620 outputs a sound signal via wired communication. The displacement signal output from the chestpiece 110 is filtered and amplified by the filter / amplifier 618 and supplied to the A / D converter 611 and the amplifier 615. The amplifier 615 further amplifies the output from the filter / amplifier 618 and supplies it to the wired communication unit 617. The wired communication unit 617 provides the amplified sound signal to the sound output device 620. The wired communication unit 617 is, for example, a 3.5 mm AUX terminal. The amplification gain of the amplifier 615 is adjusted by the volume adjustment unit 616. The sound output device 620 may be considered to constitute a part of the electronic auscultation device 100. In this case, the electronic stethoscope device 100 includes a chestpiece 110 , a grip portion 120 , and a sound output device 620 .

[0048] Next, the process by which the sound output device 620 outputs a sound signal via wireless communication will be described. The A / D converter 611 digitizes the output from the filter / amplifier 618. The digital displacement signal is then amplified by the amplifier 612 and supplied to the encoder 613. The encoder 613 performs signal processing, such as data compression and encoding, on the amplified sound signal to generate sound data for wireless communication. The order of processing by the amplifier 612 and the encoder 613 may be reversed. Then, a wireless communication unit 614 compliant with a wireless communication standard such as Bluetooth (registered trademark) provides the processed sound output data to the sound output device 620. The amplification gain of the amplifier 612 is adjusted by the volume adjustment unit 616. Although the above-described example of the electronic auscultation device 100 is capable of outputting a sound signal via both wireless and wired communication, it may also be capable of outputting a sound signal via only one of these communication methods.

[0049] The output of sound signals to the computer 630 is similar to the output of sound signals to the sound output device 620. The computer 630 can also visually display waveform data generated based on the sound signals. The waveform data may be generated by the computer 630 or by the electronic auscultation device 100. Furthermore, part or all of the signal processing and sound output processing by the electronic auscultation device 100 may be performed by an external device (e.g., the sound output device 620 or the computer 630).

[0050] The electronic auscultation device 100 according to the first embodiment can accurately detect the displacement of the biological surface 300 regardless of the frequency of vibration of the biological surface 300. Therefore, the electronic auscultation device 100 enables good auscultation of both relatively low-frequency biological sounds of about 10 Hz, such as heartbeat sounds emitted by the body due to heartbeats, and relatively high-frequency biological sounds emitted by the body due to breathing.

[0051] [Details of an example of operation of the electronic auscultation device in the first embodiment] The operation of the chestpiece 110 of the electronic auscultation device 100 in the first embodiment will be described in more detail with reference to Figure 7. Figure 7(a) shows the diaphragm 206 in an unpressured state (i.e., flat state). Figure 7(b) shows the diaphragm 206 in a state pressed by the biological surface 300. In each of Figures 7(a) and 7(b), the lower side shows a cross-sectional view of the chestpiece 110, and the upper side shows a plan view of the chestpiece 110. In the plan view, only the light-emitting element 202, the light-receiving element 204, the reflecting member 207, the light-shielding wall 704, and the light-shielding wall 705 are shown to clarify the positional relationship of the components.

[0052] 7, a stop is formed on the incident light 211 side by the light-shielding wall 704, and a stop is formed on the reflected light 212 side by the light-shielding wall 705. Therefore, part of the light emitted by the light-emitting element 202 is blocked by the light-shielding wall 704 and does not reach the reflecting member 207. Furthermore, at least part of the light reflected by the reflecting member 207 is blocked by the light-shielding wall 705, depending on the position of the reflecting member 207.

[0053] 7(a) and 7(b), incident light 211 and reflected light 212 indicate light beams that reach the light receiving element 204. In FIG. 7(b), part of the light that is emitted from the light emitting element 202, passes through the opening in the light-shielding wall 704, and is reflected by the reflecting member 207 is blocked by a portion of the light-shielding wall 705 that is above the reflected light 212, and does not reach the light receiving element 204.

[0054] 7(a), the portion of the reflecting member 207 that is reached by the incident light 211 when the diaphragm 206 is not pressed is represented as the effective range 700. The effective range 700 is the portion of the reflecting member 207 that reflects the light that reaches the light receiving element 204. When the diaphragm 206 is not pressed, the effective range 700 is equal to the range that the light from the light emitting element 202 reaches.

[0055] Within the effective range 700, the position farthest from the light-emitting element 202 in the x-axis direction is referred to as the far-end position 700a. If there are multiple such positions, one of them is referred to as the far-end position 700a. The part of the incident light 211 that reaches the far-end position 700a is referred to as the far-end incident light 211a. The far-end incident light 211a means that the optical path from the light-emitting element 202 to the reflecting member 207 is the longest. The incident angle of the incident light 211 to the reflecting member 207 reaches a maximum value 703a at the far-end position 700a.

[0056] Within the effective range 700, the position closest to the light-emitting element 202 in the x-axis direction is referred to as the near-end position 700b. If there are multiple such positions, one of them is referred to as the near-end position 700b. The portion of the incident light 211 that reaches the near-end position 700b is referred to as the near incident light 211b. The near incident light 211b means that the optical path from the light-emitting element 202 to the reflecting member 207 is the shortest. The angle of incidence of the incident light 211 to the reflecting member 207 reaches a minimum value 703b at the near-end position 700b. Of the light emitted from the light-emitting element 202, light that is not included between the far incident light 211a and the near incident light 211b is attenuated by being reflected multiple times by the baffle wall 704.

[0057] 7(a), the portion of the light receiving element 204 that is reached by the reflected light 212 is represented as a reachable range 701. The reachable range 701 is the portion of the light receiving element 204 that is reached by light that is irradiated by the light emitting element 202 and reflected by the reflecting member 207.

[0058] The reflected light of the distant incident light 211a is referred to as the bottom-end reflected light 212a. The bottom-end reflected light 212a is the light of the reflected light 212 located lowest in the z-axis direction (i.e., the portion closest to the diaphragm 206). The position within the reachable range 701 at which the bottom-end reflected light 212a reaches is referred to as the bottom-end position 701a. In the configuration of FIG. 7(a), the bottom-end position 701a can also be rephrased as the position within the reachable range 701 that is closest to the diaphragm 206 in the normal direction (i.e., the z-axis direction) of the diaphragm 206 when not pressed. In the configuration of FIG. 7(a), the bottom-end position 701a can also be rephrased as the position within the reachable range 701 at which the light with the maximum reflection angle on the reflecting member 207 reaches (i.e., the bottom-end reflected light 212a). This maximum reflection angle is equal to the maximum incident angle 703a. Furthermore, in the configuration of FIG. 7(a), the lower end position 701a can also be said to be the position farthest from the light emitting element 202 in a plan view of the diaphragm 206 when it is not pressed.

[0059] The reflected light of the near incident light 211b is referred to as the upper end reflected light 212b. The upper end reflected light 212b is the light of the reflected light 212 located at the uppermost position in the z-axis direction (i.e., the portion farthest from the diaphragm 206). The position within the reachable range 701 at which the upper end reflected light 212b reaches is referred to as the upper end position 701b. In the configuration of FIG. 7(a), the upper end position 701b can also be rephrased as the position within the reachable range 701 that is farthest from the diaphragm 206 in the normal direction (i.e., the z-axis direction) of the diaphragm 206 when not pressed. In the configuration of FIG. 7(a), the upper end position 701b can also be rephrased as the position within the reachable range 701 at which the light with the smallest reflection angle on the reflecting member 207 reaches (i.e., the upper end reflected light 212b). This minimum reflection angle is equal to the minimum incident angle 703b. Furthermore, in the configuration of FIG. 7(a), the upper end position 701b can also be said to be the position closest to the light emitting element 202 in a plan view of the diaphragm 206 when it is not pressed.

[0060] As shown in FIG. 7(b), when the diaphragm 206 is pressed by the biological surface 300, the positions of the effective range 700, the far end position 700a, the near end position 700b, the reachable range 701, the lower end position 701a, and the upper end position 701b each change.

[0061] As shown in FIGS. 7( a) and 7(b), the upper end position 701b is determined by a portion of the light-shielding wall 705 that is above the reflected light 212. Therefore, the portion of the light-shielding wall 704 that is below the incident light 211 does not need to block the light emitted from the light-emitting element 202. For example, the portion of the light-shielding wall 704 that is below the incident light 211 does not need to be provided. Furthermore, the lower end position 701a is determined by a portion of the light-shielding wall 704 that is above the incident light 211. Therefore, the portion of the light-shielding wall 705 that is below the reflected light 212 does not need to block the light reflected by the reflecting member 207. For example, the portion of the light-shielding wall 705 that is below the reflected light 212 does not need to be provided.

[0062] The positions of the reflecting member 207 and the effective area 700 relative to the diaphragm 206 will be described in more detail with reference to Figure 22. Figure 22(a) is a diagram focusing on the effective area 700 in Figure 7(a) (i.e., the effective area 700 when the diaphragm 206 is flat), and Figure 22(b) is a diagram focusing on the effective area 700 in Figure 7(b) (i.e., the effective area 700 when the diaphragm 206 is pressed). Figure 22 shows the center 206e of the diaphragm 206 (also shown in Figures 2 and 3), the center 207b of the reflecting member 207, and the center 700c of the effective area 700.

[0063] The center 700c of the effective range 700 moves closer to the light emitting element 202 as the displacement of the diaphragm 206 increases. Also, the width of the effective range 700 in the x-axis direction decreases as the displacement of the diaphragm 206 increases.

[0064] The effective range 700 is determined by the relative positions of the light-emitting element 202, the light-receiving element 204, the apertures 209 and 210, and the diaphragm 206. Therefore, the reflecting member 207 is disposed at a position where the effective range 700 is included in the upper surface of the reflecting member 207 (i.e., the light-reflecting surface 1701) even if the diaphragm 206 is displaced. The position of the boundary of the effective range 700 close to the light-emitting element 202 hardly changes even if the diaphragm 206 is displaced. Therefore, as long as the effective range 700 is included in the light-reflecting surface 1701 when the diaphragm 206 is flat, the effective range 700 will be included in the light-reflecting surface 1701 even if the diaphragm 206 is displaced. In the example of FIG. 22 , the reflecting member 207 is disposed on the diaphragm 206 so that the center 207b of the reflecting member 207 is closer to the light-emitting element 202 than the center 206e of the diaphragm 206.

[0065] [Change in the range of reflected light in the electronic auscultation device according to the first embodiment] Changes in reachable range 701, which is the portion of reflected light 212 that reaches light receiving element 204, will be described with reference to Fig. 8. Fig. 8 shows a plan view of the light receiving surface of light receiving element 204. The left side of Fig. 8 shows the position of reachable range 701 when diaphragm 206 is not pressed. The right side of Fig. 8 shows the position of reachable range 701 when diaphragm 206 is pressed by biological surface 300.

[0066] To explain the directions, a coordinate system CS' is attached to FIG. 8. The coordinate system CS' is a two-dimensional Cartesian coordinate system having x'-axis and y'-axis that are perpendicular to each other. The y'-axis coincides with the y-axis of the coordinate system CS. The x'-axis is parallel to the xz plane of the coordinate system CS. In the following description, the positive direction of the x'-axis is referred to as the upper side, and the negative direction of the x'-axis is referred to as the lower side.

[0067] The surface of the light receiving element 204 that faces the internal space 213 is the light receiving surface. An area sensor is disposed on the light receiving surface. Using this area sensor, the light receiving element 204 detects the amount of light irradiated onto the light receiving surface. The light receiving surface may have a rectangular shape. Of the four sides of the light receiving surface, the side that is parallel to the diaphragm 206 and closer to the diaphragm 206 is referred to as side 204a.

[0068] As shown in FIG. 8, the range of light that reaches light receiving element 204 (i.e., reachable range 701) changes in the x′-axis direction as reflecting member 207 moves. Specifically, the greater the amount of displacement of diaphragm 206 from its flat state, the shorter the distance between bottom end position 701a and top end position 701b, and the smaller the area of ​​reachable range 701. Therefore, the greater the amount of displacement of diaphragm 206 from its flat state, the less light is received by light receiving element 204. As shown in FIG. 8, the amount of movement of bottom end position 701a associated with the movement of reflecting member 207 is greater than the amount of movement of top end position 701b associated with the movement of reflecting member 207.

[0069] 8, the change in reachable range 701 in the x'-axis direction is larger than the change in reachable range 701 in the y'-axis direction. Therefore, in order to increase the dynamic range of light receiving element 204, it is preferable to make the width of light receiving element 204 in the x'-axis direction larger than the width of light receiving element 204 in the y'-axis direction. More specifically, it is preferable to make the width of light receiving element 204 in the x'-axis direction three times or more the width of light receiving element 204 in the y'-axis direction.

[0070] [Modification of the electronic auscultation device in the first embodiment] A modified example of the chestpiece 110 will be described with reference to Fig. 9. In Fig. 9, differences from Fig. 7 will be described, and duplicated explanations of points that may be the same as those in Fig. 7 will be omitted.

[0071] 9, chestpiece 110 further includes lens 900 between light-emitting element 202 and reflecting member 207. Lens 900 converts the diffused light emitted by light-emitting element 202 into parallel light. This parallel light is irradiated onto reflecting member 207, so chestpiece 110 can eliminate the need for a stop on the incident light 211 side.

[0072] The change in reachable range 701 is the same as that described in Fig. 7. Therefore, the range of light that reaches light receiving element 204 (i.e., reachable range 701) changes in the x'-axis direction as reflecting member 207 moves.

[0073] In the above-described embodiment, the normal to the light receiving surface of the light receiving element 204 is inclined with respect to the z-axis direction (i.e., the normal direction to the diaphragm 206). Alternatively, the normal to the light receiving surface of the light receiving element 204 may coincide with the z-axis direction. In other words, the light receiving surface is parallel to the diaphragm 206.

[0074] In the above-described embodiment, chestpiece 110 includes only one light-emitting element 202. Alternatively, chestpiece 110 may include multiple light-emitting elements 202. Light emitted by the multiple light-emitting elements 202 may be reflected by reflecting member 207 and reach light-receiving element 204. Light-receiving element 204 may detect the displacement of diaphragm 206 based on the total amount of light received by the multiple light-receiving elements 204. Chestpiece 110 may include multiple light-receiving elements 204. Each of the multiple light-receiving elements 204 may receive light emitted from a different light-emitting element 202 and reflected by reflecting member 207. The displacement of diaphragm 206 may be detected based on the total amount of light received by the multiple light-receiving elements 204.

[0075] [Configuration of the light-reflecting surface of the electronic stethoscope] The configuration of the light-reflecting surface of the chestpiece 110 and its variations will be described in detail with reference to FIG. 17. FIG. 17(a) is a diagram focusing on the diaphragm 206 and the reflecting member 207 in FIG. 2(a). First, the configuration of the diaphragm 206 will be described. The diaphragm 206 is a laminated plate of glass epoxy resin, which is made by impregnating glass fiber with epoxy resin and then heat-curing it. Examples of suitable materials for the diaphragm 206 include glass epoxy resin, plastics such as polyester, glass fiber-reinforced plastic, flexible plastic, silicone, rubber, glass fiber, polycarbonate, carbon fiber composite, polystyrene, and metals such as stainless steel. The thickness of the diaphragm 206 is preferably in the range of 130 to 510 μm. In this embodiment, a diaphragm with a thickness of 230 μm is used as an example. The diaphragm 206 is also integrated with a rim for attaching the diaphragm 206 to the housing 208, and the Shore A durometer hardness of the rim is approximately 40 to 110.

[0076] Next, the configuration of the reflecting member 207 will be described. The upper surface of the reflecting member 207 is referred to as the light-reflecting surface 1701. The light-reflecting surface 1701 is located at a position where light emitted by the light-emitting element 202 directly reaches it. The light-reflecting surface 1701 reflects the light emitted by the light-emitting element 202 toward the light-receiving element 204. The reflecting member 207 is formed of a material with a relatively high reflectivity so that the light-receiving element 204 can accurately detect the light reflected from the light-reflecting surface 1701. The reflectivity of the light-reflecting surface 1701 is preferably approximately 95 to 96%, and desirably at least 90% or higher. An example of a material with such a reflectivity is Metalme (registered trademark) manufactured by Toray Industries, Inc. However, the reflecting member 207 may be a sheet-like member like Metalme, or alternatively, may be a cured paint. The reflecting member 207 in this embodiment has a thickness of 100 μm. The thickness of the reflecting member 207 is set to be at least thinner than the thickness of the diaphragm 206. The Young's modulus of the reflecting member 207 is set to be smaller than that of the diaphragm 206 .

[0077] The area where the reflecting member 207 is attached is less likely to deform because the diaphragm 206 and the reflecting member 207 overlap. In order not to hinder the deformation of the diaphragm 206, it is preferable that the reflecting member 207 is thin and has a small Young's modulus. Furthermore, if the reflecting member 207 is thin and made of a material with a low Young's modulus, the reflecting member 207 can also deform so as to bend, as shown in FIG. 7(b). When the reflecting member 207 bends with respect to the incident light 211, the reflecting member 207 tilts, and the reflected light 212 moves in the z direction. As a result, the reflected light 212 irradiating the light receiving element 204 becomes smaller, making it possible to detect displacement with high sensitivity.

[0078] As described above, light that directly reaches the light-receiving element 204 from the light-emitting element 202, is reflected by the light-reflecting surface 1701, and is detected as a displacement signal representing the displacement of the diaphragm 206. However, light other than this that reaches the light-receiving element 204 becomes noise in the displacement signal. Therefore, the portion of the inner surface 206b of the diaphragm 206 that is not covered by the reflecting member 207 is configured to have a lower reflectance than the reflecting member 207. In the following description, a surface that is located around the light-reflecting surface 1701 and has a lower reflectance than the light-reflecting surface 1701 is referred to as a low-reflecting surface 1702. In FIG. 17(a), the portion of the inner surface 206b of the diaphragm 206 that is not covered by the reflecting member 207 functions as the low-reflecting surface 1702. Since the inner surface 206b of the diaphragm 206 has the low-reflection surface 1702, it is possible to prevent light other than light reflected by the light-reflecting surface 1701 (for example, light diffusely reflected in the internal space 213) from reaching the light receiving element 204. This improves the S / N ratio of the displacement signal, allowing displacement of the surface of the living body to be detected with high accuracy.

[0079] Modified examples of the configuration of Fig. 17(a) will be described with reference to Fig. 17(b) to Fig. 17(e). In any of the modified examples of Fig. 17(b) to Fig. 17(e), the positions and sizes of the light reflecting surface 1701 and the low reflecting surface 1702 may be the same as those of the configuration of Fig. 17(a).

[0080] In the configuration example of FIG. 17(b), the inner surface 206a of the diaphragm 206 is covered with a low-reflection member 1703, and a reflective member 207 is disposed on the low-reflection member 1703. The low-reflection member 1703 is a member having a lower reflectivity than the reflective member 207. The low-reflection member 1703 may be a sheet-like member or may be a hardened paint. In this configuration example, the portion of the upper surface of the low-reflection member 1703 that is not covered by the reflective member 207 functions as a low-reflection surface 1702. The low-reflection member 1703 covers the entire inner surface 206a. Alternatively, the low-reflection member 1703 may cover only a portion of the inner surface 206a.

[0081] 17(c), the inner surface 206a of the diaphragm 206 is covered with the reflective member 207, and a portion of the upper surface of the reflective member 207 is covered with the low-reflective member 1703. In this configuration example, the portion of the upper surface of the reflective member 207 that is not covered with the low-reflective member 1703 functions as the light-reflecting surface 1701, and the upper surface of the low-reflective member 1703 functions as the low-reflective surface 1702. The reflective member 207 covers the entire inner surface 206a. Alternatively, the reflective member 207 may cover only a portion of the inner surface 206a.

[0082] 17(d), a portion of the inner surface 206a of the diaphragm 206 is covered with the reflective member 207, and the other portion of the inner surface 206a of the diaphragm 206 is covered with the low-reflective member 1703. In this configuration example, the upper surface of the reflective member 207 functions as the light-reflecting surface 1701, and the upper surface of the low-reflective member 1703 functions as the low-reflective surface 1702.

[0083] 17(e), the inner surface 206a of the diaphragm 206 is covered with a reflective member 207, and a portion of the upper surface of the reflective member 207 is processed to reduce reflectivity. In this configuration example, the unprocessed portion of the upper surface of the reflective member 207 functions as a light-reflecting surface 1701, and the processed portion functions as a low-reflecting surface 1702. The reflective member 207 covers the entire inner surface 206a. Alternatively, the reflective member 207 may cover only a portion of the inner surface 206a.

[0084] The glossiness of light-reflecting surface 1701 may be higher than the glossiness of low-reflecting surface 1702. For example, the glossiness of light-reflecting surface 1701 for light with an incident angle of 60 degrees may be 900 or higher. The glossiness of low-reflecting surface 1702 for light with an incident angle of 60 degrees may be 100 or lower.

[0085] Table 1 below shows the glossiness of various materials. The glossiness in Table 1 is a value (unit: Gloss Unit (GU)) measured using a surface reflection analyzer RA-532H manufactured by Canon Inc. Metamy is a material suitable for the reflective member 207. Films A to C and black paint are all suitable materials for the low-reflection member 1703.

[0086] [Table 1]

[0087] In order to increase the displacement of the diaphragm 206, it is preferable that the light-reflecting surface 1701 and the area surrounding it be flexible (low rigidity). In all of the configuration examples shown in FIGS. 17(a) to 17(e), the reflective member 207 is provided on the inner surface 206a of the diaphragm 206. This makes the diaphragm 206 less likely to deflect than when no reflective member is provided on the inner surface 206a of the diaphragm 206. In other words, in a configuration in which a reflective member is provided on the diaphragm 206, the reflective member can hinder the overall deflection of the diaphragm 206. However, in this embodiment, as described above, the reflective member 207 is made of a material with a lower Young's modulus than the diaphragm 206, and the reflective member 207 is made of a material thinner than the diaphragm 206. This reduces the influence of the reflective member 207 when the diaphragm 206 vibrates. This allows for a large displacement of the diaphragm 206. As a result, the dynamic range of the light-receiving element 204 can be increased. 17(d), the rigidity of light reflecting surface 1701 may be made higher than the rigidity of low reflecting surface 1702 by forming reflecting member 207 from a material with higher rigidity than low reflecting member 1703. In the configuration example of Fig. 17(e), the rigidity of light reflecting surface 1701 may be made higher than the rigidity of low reflecting surface 1702 by processing the surface of low reflecting surface 1702 so as to reduce the rigidity of reflecting member 207.

[0088] Light that is diffusely reflected within internal space 213 can be reduced not only by lowering the reflectance of low-reflection surface 1702, but also by lowering the reflectance of other portions facing internal space 213. Therefore, holding member 201 may be configured so that the reflectance of the portion facing internal space 213 is lower than that of light-reflecting surface 1701. For example, the portion of holding member 201 facing internal space 213 may be covered with black paint.

[0089] [Effect of reflectivity on low-reflectivity surfaces] 19 to 21, the effect of the reflectance of the low-reflection surface 1702 on the amount of light received by the light receiving element 204 will be described. As shown in Fig. 20 and Fig. 21, in the following description, the holding member 201 is made up of a base holding member 1104, a lower holding member 1105, and an upper holding member 1106. Details of the structures of the base holding member 1104, the lower holding member 1105, and the upper holding member 1106 will be described in detail in the second embodiment described later.

[0090] Graph 1900 in Figure 19 shows the results of an optical simulation. In this simulation, the reflectance of the base holding member 1104 was set to 75%, the reflectance of the upper holding member 1105 and the lower holding member 1106 to 50%, the reflectance of the light-reflecting surface 1701 to 95%, and the reflectance of the low-reflecting surface 1702 was changed to eight values ​​from 0% to 95%. The horizontal axis of graph 1900 represents the reflectance of the low-reflecting surface 1702, and the vertical axis of graph 1900 represents the amount of light received by the light-receiving element 204 when the light-emitting element 202 irradiates light of a specific intensity while the diaphragm 206 is flat. The amount of received light is scaled so that the amount of received light is 1 when the reflectance of the low-reflecting surface 1702 is 0%.

[0091] Graph 1900 shows that as the reflectance of low-reflectivity surface 1702 increases from 0%, the amount of received light also increases, and when the reflectance of low-reflectivity surface 1702 exceeds 50%, the amount of received light remains almost constant. The increase in the amount of received light is thought to be caused by light being diffused by low-reflectivity surface 1702 and reaching light-receiving element 204. The light diffused by low-reflectivity surface 1702 becomes noise in relation to the displacement of diaphragm 206. In the above-described simulation settings, when the reflectance of low-reflectivity surface 1702 becomes less than 50%, the effect of reducing the noise contained in the amount of received light begins to appear, and the lower the reflectance of low-reflectivity surface 1702, the more the noise is reduced. Therefore, for example, diaphragm 206 is configured so that the reflectance of low-reflectivity surface 1702 is less than 50%.

[0092] In this embodiment, the light emitted from the light emitting element 202 is narrowed by the aperture 209. If a portion of the aperture 209 on the diaphragm film 206 side is omitted, the light emitted from the light emitting element 202 will reach the low-reflection surface 1702, which may increase the amount of diffusely reflected light and the noise contained in the amount of received light. By forming the low-reflection surface 1702 from a material with a reflectance extremely close to 0%, such as a light-blocking paint, the noise caused by diffusely reflected light can be reduced even if a portion of the aperture 209 is omitted.

[0093] FIG. 20 shows the path of light when the reflectivity of the low-reflectivity surface 1702 is high (specifically, 95%), and FIG. 21 shows the path of light when the reflectivity of the low-reflectivity surface 1702 is low (specifically, 5%). FIGS. 20(a) and 21(a) are cross-sectional views focusing on the portion of the chestpiece 110 that constitutes the internal space 213, and FIGS. 20(b) and 21(b) are perspective views of this portion. In FIGS. 20(c) and 21(c), region 2000 indicates the light receiving surface of the light receiving element 204, and region 2001 indicates the portion of the light receiving surface of the light receiving element 204 that is visible from the light reflecting surface 1701 without being blocked by the aperture 210. In FIGS. 20(c) and 21(c), the position where light arrives is indicated by a darker color.

[0094] A portion of the light emitted from the light-emitting element 202 passes directly through the aperture 209 and reaches the light-reflecting surface 1701. Another portion of the light emitted from the light-emitting element 202 may be reflected one or more times by the upper holding member 1105 or the lower holding member 1106, pass through the aperture 209, and reach the low-reflecting surface 1702.

[0095] As shown in Fig. 20, when the reflectance of low-reflection surface 1702 is high, light that reaches low-reflection surface 1702 is diffused, and the light reaches the outside of region 2001. Such light can become noise. On the other hand, as shown in Fig. 21, when the reflectance of low-reflection surface 1702 is low, almost no light that reaches low-reflection surface 1702 is reflected, and therefore the amount of light that reaches the outside of region 2001 is reduced. Therefore, noise is also reduced.

[0096] <Second embodiment> [Hardware configuration of the electronic auscultation device in the second embodiment] An example of the configuration of an electronic auscultation device 1000 according to the second embodiment will be described with reference to Figures 10 to 13. Below, differences from the electronic auscultation device 100 according to the first embodiment will be mainly described, and redundant description of points that may be the same as those in the electronic auscultation device 100 will be omitted. The appearance of the electronic auscultation device 1000 is the same as the electronic auscultation device 100 described with reference to Figure 1. The modifications described in the first embodiment may also be applied to the second embodiment.

[0097] The hardware configuration of the electronic auscultation device 1000 will be described with reference to Fig. 10. The difference between Fig. 10 and Fig. 6 is that the electronic auscultation device 1000 includes a chestpiece 1010 and a sound output unit 1020 instead of the chestpiece 110 and sound output unit 610 of the electronic auscultation device 100. The electronic auscultation device 1000 is composed of the chestpiece 1010 and the sound output unit 1020 included in the grip unit 120 (Fig. 1). The chestpiece 1010 has a displacement detection unit 1011 and a vibration detection unit 1012. Similar to the electronic auscultation device 100, the displacement detection unit 1011 is composed of main components including a light-emitting element 202, a light-receiving element 204, and a reflecting member 207. The displacement detection unit 1011 generates a displacement signal (i.e., a signal representing the displacement of the diaphragm 206) based on the amount of light emitted by the light-emitting element 202, reflected by the reflecting member 207, and received by the light-receiving element 204. Alternatively, the displacement detection unit 1011 may detect the displacement signal in another manner based on the light received by the light-receiving element 204. For example, the light-emitting element 202 may emit a laser beam toward the reflecting member 207. The laser beam reflected by the reflecting member 207 reaches the light-receiving element 204. The position at which the laser beam reaches the light-receiving element 204 varies depending on the displacement of the diaphragm 206. Therefore, the displacement detection unit 1011 may detect the displacement signal based on the position of the light received by the light-receiving element 204. When the light-emitting element 202 emits a laser beam, the chestpiece 1010 does not need to include the apertures 209 and 210. When the light emitting element 202 emits laser light, the light receiving element 204 may be a two-dimensional area sensor or a one-dimensional array sensor.

[0098] The vibration detection unit 1012 detects air vibrations caused by the displacement of the diaphragm 206. The vibration detection unit 1012 is also called a sound detection unit because it detects sounds represented by air vibrations. The vibration detection unit 1012 is configured by, for example, a capacitor microphone 1101 (FIG. 11). The vibration detection unit 1012 generates a sound signal representing the detected air vibrations. The sound signal may be an electric signal (for example, a voltage signal). The displacement signal generated by the displacement detection unit 1011 and the sound signal generated by the vibration detection unit 1012 are each supplied to the sound output unit 1020.

[0099] The sound output unit 1020 performs signal processing on the displacement signal and sound signal supplied from the chestpiece 1010 in the same manner as the sound output unit 610 of the electronic auscultation device 100, and outputs the results to an external device (e.g., the sound output device 620 or the computer 630) outside the sound output unit 1020. The frequency bands to which the displacement detection unit 1011 and the vibration detection unit 1012 have high sensitivity may differ. For example, the displacement detection unit 1011 can detect vibrations (e.g., heartbeat sounds) in a low-frequency band (e.g., 100 Hz or less) with better sensitivity than the vibration detection unit 1012. On the other hand, the vibration detection unit 1012 can detect vibrations (e.g., respiratory sounds) in a high-frequency band (e.g., 100 Hz or more) with better accuracy than the displacement detection unit 1011. Therefore, since the sound output unit 1020 can output both the displacement signal and the sound signal, the electronic auscultation device 1000 can accurately detect vibrations in a wide frequency band.

[0100] The sound output unit 1020 includes an output selection unit 1021 in addition to the components included in the sound output unit 610 of the electronic auscultation device 100. The output selection unit 1021 selects which of the displacement signal and the sound signal supplied from the chestpiece 1010 to output to the outside. For example, when the output destination is the sound output device 620, the output selection unit 1021 outputs only the selected one of the displacement signal and the sound signal. When the output destination is the computer 630, the output selection unit 1021 may output only the selected one of the displacement signal and the sound signal, or may output both the displacement signal and the sound signal. In this way, the sound output unit 1020 can selectively output the displacement signal and the sound signal to the outside.

[0101] The operation unit 123 of the electronic auscultation device 1000 receives a user's designation regarding whether to output a displacement signal or an audio signal. In this embodiment, the operation unit 123 in FIG. 1 is provided with a mode switching button 123c. In response to pressing the mode switching button 123c, the output selection unit 1021 switches the signal to be output externally between the displacement signal and the audio signal. For example, when auscultating heartbeat sounds, the user operates the mode switching button 123c provided on the operation unit 123 to select the heartbeat sound mode. On the other hand, when auscultating breath sounds, the user operates the mode switching button 123c provided on the operation unit 123 to select the breath sound mode. Information regarding the operation mode designated by the user is sent to the output selection unit 1021. Based on this operation mode information, the output selection unit 1021 selects whether to output a displacement signal representing the displacement detected by the displacement detection unit 1011 or an audio signal detected by the microphone 1101. The operation unit 123 also has volume adjustment buttons 123a and 123b for adjusting the gain of the displacement signal output by the electronic auscultation device 100. The volume adjustment buttons 123a and 123b are used to adjust the volume of the sound output by the electronic auscultation device 100. Furthermore, the display unit 122 of the electronic auscultation device 1000 has an LED as an indicator that displays whether the signal currently selected to be output is a displacement signal or a sound signal. Depending on the lighting state of this LED, the user can visually determine whether the operating mode is the heartbeat sound mode or the breath sound mode.

[0102] Output selector 1021 controls wireless communication unit 614 and wired communication unit 617 to determine the type of signal to be output externally. Alternatively, output selector 1021 may determine whether a displacement signal or a sound signal is to be supplied to filter / amplifier 618. Furthermore, in the example of FIG. 10 , sound output unit 1020 includes output selector 1021, but chestpiece 1010 may instead include output selector 1021. Output selector 1021 in chestpiece 1010 may determine the type of signal to be supplied to sound output unit 1020.

[0103] [Chestpiece configuration of the electronic stethoscope device in the second embodiment] An example of the structure of the chestpiece 1010 will be described with reference to FIGS. 11 to 13. FIG. 11(a) is a plan view of the chestpiece 1010. FIG. 11(b) is an enlarged cross-sectional view of the chestpiece 1010 taken along line AA in FIG. 11(a). FIG. 11(c) is an enlarged cross-sectional view of the chestpiece 1010 taken along line BB in FIG. 11(a). FIG. 12(a) is an exploded perspective view of the chestpiece 1010, with each component separated. FIG. 12(b) is a perspective view showing the shape of the sealed space 1100. FIGS. 13(a) to 13(c) are perspective views of the lower holding member 1105 viewed from various angles. FIGS. 13(d) to 13(f) are perspective views of the upper holding member 1106 viewed from various angles. FIG. 13(g) is a perspective view of the base holding member 1104 viewed from a certain angle. In Fig. 11(a), for ease of understanding, the light-emitting element 202, the light-receiving element 204, the reflecting member 207, and the microphone 1101 are depicted so as to be visible, but these components are hidden by the housing 208. In Fig. 11(b) and Fig. 11(c), for ease of understanding, cross sections of the same components are indicated by the same hatching, and cross sections of different components are indicated by different hatching. In Figs. 11 to 13, the mechanism for attaching the chestpiece 1010 to the grip portion 120 is omitted.

[0104] In addition to the components included in the chestpiece 110 of the electronic stethoscope device 100, the chestpiece 1010 further includes a microphone 1101, a sealing member 1102, and a relay circuit board 1103. As described above, the microphone 1101 constitutes the vibration detection unit 1012.

[0105] The relay circuit board 1103 is connected to the light-emitting circuit board 203 by a lead wire (not shown). The relay circuit board 1103 transmits a control signal to the light-emitting circuit board 203 to instruct it to emit light and supplies power through this lead wire. The relay circuit board 1103 is also connected to the light-receiving circuit board 205 by a lead wire (not shown). The relay circuit board 1103 receives a displacement signal from the light-receiving circuit board 205 through this lead wire and supplies power to the light-receiving circuit board 205. The relay circuit board 1103 is also connected to the microphone 1101 by a lead wire (not shown). The relay circuit board 1103 receives an audio signal from the microphone 1101 through this lead wire and supplies power to the microphone 1101. The relay circuit board 1103 is also connected to a circuit board in the grip part 120 by a cable (not shown). The relay circuit board 1103 transmits displacement signals and sound signals to the circuit board in the grip portion 120 via this cable, receives control signals for controlling the operation of the chestpiece 110 from the circuit board in the grip portion 120, and receives a supply of power. A hole 208a is formed in the housing 208 for passing a cable connecting the relay circuit board 1103 and the circuit board in the grip portion 120. In this specification, unless otherwise specified, a "hole" refers to a through-hole that penetrates the member in which the hole is formed. On the other hand, a "recess" refers to a hole that does not penetrate the member in which the recess is formed.

[0106] The holding member 201 is composed of a base holding member 1104, a lower holding member 1105, and an upper holding member 1106. A diaphragm 206 is attached to the base holding member 1104 so as to cover the lower surface of the base holding member 1104. The outer periphery of the diaphragm 206 may be folded back to form a recess, and the diaphragm 206 is attached to the base holding member 1104 by fitting a protrusion on the outer periphery of the base holding member 1104 into this recess. Alternatively, the diaphragm 206 may be attached to the base holding member 1104 by, for example, adhesive bonding. Because there is a gap between the lower surface of the base holding member 1104 and the diaphragm 206, the diaphragm 206 can be displaced relative to the lower surface of the base holding member 1104. The lower surface of the base holding member 1104 has a recess near its center so as not to hinder the displacement of the diaphragm 206.

[0107] The housing 208 is attached to the base holding member 1104 so as to cover the upper surface of the base holding member 1104. The base holding member 1104 has a screw thread or a thread groove on its outer periphery, and the housing 208 has a screw groove or a thread on the inside of its lower end. These screw threads and the screw grooves fit together to attach the housing 208 to the base holding member 1104. Alternatively, the housing 208 may be attached to the base holding member 1104 by, for example, gluing. The housing 208 covers the light-emitting element 202, the light-emitting circuit board 203, the light-receiving element 204, the light-receiving circuit board 205, and the microphone 1101 attached to the holding member 201, and has the function of insulating ambient sound so that it is not detected as noise.

[0108] Two more holding members (a lower holding member 1105 and an upper holding member 1106) are arranged on the base holding member 1104. The lower holding member 1105 is located on the opposite side of the base holding member 1104 from the diaphragm 206 in the z direction. A recess 1105d formed on the bottom surface of the lower holding member 1105 fits into a protrusion 1104d formed on the top surface of the base holding member 1104, and the lower holding member 1105 is aligned with the base holding member 1104.

[0109] The upper holding member 1106 is disposed above the base holding member 1104 and the lower holding member 1105 in the z direction. The upper holding member 1106 is located on the opposite side of the base holding member 1104 from the diaphragm 206. The lower holding member 1105 is located between the upper holding member 1106 and the base holding member 1104. A protrusion 1106a formed on the lower surface of the upper holding member 1106 fits into a hole 1105b formed in the lower holding member 1105, thereby aligning the upper holding member 1106 with the lower holding member 1105.

[0110] The relay circuit board 1103 is disposed on the upper holding member 1106. A screw (not shown) passing through a hole 1103a formed in the relay circuit board 1103 and a hole 1106c formed in the upper holding member 1106 is engaged with a screw hole 1104c formed in the base holding member 1104. In the illustrated example, three screw holes are formed in the base holding member 1104, and a screw passing through the relay circuit board 1103 and the upper holding member 1106 is engaged with each of these screw holes. In this way, the lower holding member 1105, the upper holding member 1106, and the relay circuit board 1103 are fixed to the base holding member 1104. The method for fixing the lower holding member 1105, the upper holding member 1106, and the relay circuit board 1103 to the base holding member 1104 is not limited to this, and they may be fixed using an adhesive, for example.

[0111] The light-emitting element 202 is inserted into a hole formed by the engagement of the upper holding member 1106 and the lower holding member 1105. The light-receiving element 204 is arranged so as to cover the hole formed by the engagement of the upper holding member 1106 and the lower holding member 1105. The microphone 1101 is arranged in a hole 1104b formed in the base holding member 1104. A sealing member 1102 is arranged between the microphone 1101 and the base holding member 1104 to seal the gap between these members, thereby improving the sealing performance of the sealed space described below. In addition, a protrusion 1106a formed on the underside of the upper holding member 1106 is arranged above the hole 1104b in the base holding member 1104. The protrusion 1106a may press the microphone 1101 downward (i.e., toward the diaphragm 206). The microphone 1101 is positioned so as not to overlap the optical path of light (i.e., incident light 211 and reflected light 212) traveling from the light-emitting element 202 to the light-receiving element 204 via the reflecting member 207 in a planar view of the diaphragm 206 (i.e., when viewed from the positive z-axis).

[0112] A T-shaped hole 1104a is formed near the center of the base holding member 1104. A hole 1105a is formed near the center of the lower holding member 1105. Incident light 211 passes through holes 1104a and 1105a from the light emitting element 202 to reach the reflecting member 207. Reflected light 212 also passes through holes 1104a and 1105a from the reflecting member 207 to reach the light receiving element 204. In this way, no other components are disposed on the optical path of light (i.e., incident light 211 and reflected light 212) traveling from the light emitting element 202 to the light receiving element 204 via the reflecting member 207. The base holding member 1104 covers the inner surface 206b of the diaphragm 206 except for the area where the reflecting member 207 is fixed.

[0113] The upper holding member 1106 has a light-shielding wall 1106d extending in a direction intersecting the diaphragm 206 (the y-z plane in the example of FIG. 11(b)). The lower holding member 1105 has a light-shielding wall 1105c extending in a direction along the diaphragm 206 (the x-y plane in the example of FIG. 11(b)). The light-shielding wall 1106d and the light-shielding wall 1105c form an aperture 209 on the incident light 211 side. That is, the light-shielding wall 1106d and the light-shielding wall 1105c each block a portion of the light emitted by the light-emitting element 202. A portion of the light-shielding wall 1105c may enter the hole 1104a in the base holding member 1104. This allows the aperture 209 to be closer to the reflecting member 207, thereby reducing the spread of the incident light 211. Furthermore, a convex portion that protrudes downward in the z direction is provided on the side of the upper holding member 1106 facing the reflected light 212, and this convex portion forms an aperture 210 that blocks a portion of the light reflected by the reflecting member 207. The light-shielding wall 1106d provided on the upper holding member 1106 and the light-shielding wall 1105c provided on the lower holding member 1105 not only serve as an aperture that blocks the incident light 211 and the reflected light 212, but also serve to narrow the sealed space. That is, the light-shielding wall 1105c and the light-shielding wall 1106d narrow the volume of the sealed space (internal space), thereby increasing the rate of volume change, which will be described later, and as a result, the sensitivity of the microphone 1101 can be improved.

[0114] In the second embodiment, the diaphragm 206, the reflecting member 207, the base holding member 1104, the lower holding member 1105, the upper holding member 1106, the light emitting element 202, the light receiving element 204, and the microphone 1101 define a sealed space 1100. Therefore, the space facing the inner surface 206b of the diaphragm 206 is a sealed space. A sealed space is a space sealed against specific substances. In other words, a sealed space is a space in which the inflow of specific substances from an external space or the external environment and the outflow of specific substances to an external space or the external environment are restricted. Therefore, there are no passages, such as gaps or holes, connecting the sealed space 1100 to the outside. The substances to be sealed may vary depending on the environment in which the electronic stethoscope device 1000 is used. For example, if the electronic auscultation device 1000 is used at atmospheric pressure, the substance to be sealed may be a gas (e.g., air), and if the electronic auscultation device 1000 is used underwater, the substance to be sealed may be a liquid (e.g., water).

[0115] [Sealed space inside the chestpiece of the electronic stethoscope device in the second embodiment] 11(b) and 11(c), the space facing the inner surface 206b of the diaphragm 206 and surrounded by the hatched components is the sealed space 1100. The portion of the lower holding member 1105 that defines the sealed space 1100 includes the above-mentioned light-shielding wall 1105c. The portion of the upper holding member 1106 that defines the sealed space 1100 includes the above-mentioned light-shielding wall 1106d. When a gap exists between the light-emitting element 202 and the holding member 201, the sealed space 1100 may be further defined by the light-emitting circuit board 203. When a gap exists between the light-receiving element 204 and the holding member 201, the sealed space 1100 may be further defined by the light-receiving circuit board 205. When a gap exists between the microphone 1101 and the holding member 201, the sealed space 1100 may be further defined by the seal member 1102.

[0116] The sealed space 1100 does not have to be sealed when the electronic auscultation device 100 is not in use. For example, the diaphragm 206 and the base holding member 1104 do not have to be in close contact when the electronic auscultation device 100 is not in use. The diaphragm 206 and the base holding member 1104 may be in close contact when the diaphragm 206 is pressed against the surface of a living body, thereby forming the sealed space 1100.

[0117] A sound detection surface 1101a of the microphone 1101 faces the sealed space 1100. This allows the microphone 1101 to detect air vibrations generated in the internal space 212 due to the vibration of the diaphragm 206. The microphone 1101 generates a sound signal representing the air vibrations.

[0118] Specifically, the portion of diaphragm 206 that comes into contact with the surface of the living body is made of a sheet-shaped flexible material. Diaphragm 206 separates sealed space 1100 from the outside of chestpiece 1010. Diaphragm 206 has the property of deforming in response to an external force applied to diaphragm 206 (for example, a force from the surface of the living body) and returning to its original shape when the external force is removed. Due to this property, the air pressure in sealed space 1100 changes in response to vibrations transmitted from the surface of the living body to diaphragm 206. Sound detection surface 1101a of microphone 1101 vibrates in response to the air pressure in sealed space 1100, and microphone 1101 converts the vibrations of sound detection surface 1101a into an electrical signal.

[0119] The inner surface 206b of the diaphragm 206 and the sound detection surface 1101a of the microphone 1101 face the sealed space 1100, so that the microphone 1101 can efficiently detect sound signals corresponding to the displacement of the surface of the living body.

[0120] The smaller the volume of the sealed space 1100, the greater the change in air pressure in the sealed space 1100 in response to the vibration of the diaphragm 206. Accordingly, the sound detected by the microphone 1101 becomes louder. Therefore, in this embodiment, the sealed space 1100 is configured so that the volume of the sealed space 1100 is smaller than the volume of the internal space of the chestpiece 110. The internal space of the chestpiece 110 may be the area surrounded by the housing 208, the base holding member 1104, and the diaphragm 206. In this embodiment, the sealed space 1110 does not face the housing 208. In other words, the sealed space 1110 is separated from the space facing the inner surface of the housing 208.

[0121] The interior space of the chestpiece 110 other than the sealed space 1110 may or may not be sealed. For example, if the electronic stethoscope device 1000 is required to be waterproof or dustproof, the interior space of the chestpiece 110 may be sealed against water or dust. As described above, the housing 208 is formed with a hole 208a for passing a cable through. The interior space of the chestpiece 110 may be sealed by sealing the gap between this hole 208a and the cable with a sealing member. If a screw is used to fix the housing 208 to the base holding member 1104 other than the hole 208a, the gap between the thread and the screw groove may be sealed with a sealing member.

[0122] In this embodiment, the space facing the inner surface 206b of the diaphragm 206 is a sealed space 1100, but for example, holes or gaps may be formed to the extent that the sensitivity does not decrease in the frequency band to be measured.

[0123] In this embodiment, the space facing the inner surface 206b of the diaphragm 206 is sealed using the base holding member 1104, the lower holding member 1105, and the upper holding member 1106. Alternatively, this space may be sealed using parts of these holding members, or other parts. Furthermore, to improve the adhesion between the multiple components that define the sealed space 1100, a buffer member may be disposed between two adjacent components. For example, a buffer member may be disposed in a gap at the contact portion between the light-emitting circuit board 203 and the holding member 201, a gap at the contact portion between the light-receiving circuit board 205 and the holding member 201, or a gap at the contact portion between the base holding member 1104 and the holding member 201. This can improve the sealing performance of the sealed space 1100.

[0124] [Sound-insulating configuration of the electronic auscultation device in the second embodiment] Microphone 1101 can detect not only air vibrations generated in sealed space 1100, but also sounds transmitted through housing 208 from outside chestpiece 1010. Therefore, housing 208 is preferably made of a material with excellent sound insulation properties.

[0125] The sound transmission loss of the housing 208 is calculated by a function that takes as input the frequency of the sound, the angle of incidence of the sound, and the surface density of the material of the housing 208. When the angle of incidence of the sound is perpendicular, the frequency of the sound is f [Hz] and the surface density of the material of the housing 208 is σ [kg / m 2 ], then the sound transmission loss TL [db] of the housing 208 is TL=18×log 10 (σ×f)-44…(Formula 3) The areal density of the material of the housing 208 is calculated by multiplying the density of the material of the housing 208 by the thickness of the housing 208.

[0126] The surface density of housing 208 and the transmission loss at various frequencies when housing 208 is 1.5 mm thick and made of brass, stainless steel, aluminum, and polycarbonate ABS are shown in Table 2 below. Polycarbonate ABS is an example of a resin.

[0127] [Table 2]

[0128] From Table 2, it can be seen that metal materials have better sound insulation properties than resin materials. Therefore, it is desirable that the housing 208 be made of a metal material. The surface density of the housing 208 may be greater than the surface density of the diaphragm. Specifically, the surface density of the housing 208 is 5 kg / m 2 It may be 10 kg / m or more, and even 10 kg / m 2 On the other hand, the holding member 201 may be made of a resin material in order to reduce the weight and cost of the chestpiece 1010.

[0129] [Configuration of the support member of the electronic stethoscope device] A detailed configuration example of the support member 201 will be described with reference to FIG. 18. FIGS. 18(a) to 18(e) are the same as FIGS. 11(a), 13(a), and 13(c) to 13(e), respectively. As described above, the diaphragm 209 is formed by the light-shielding wall 1105c of the lower holding member 1105 and the light-shielding wall 1106d of the upper holding member 1106. A portion of the light emitted by the light-emitting element 202 passes through the diaphragm 209 toward the reflecting member 207, while the remaining light is blocked by the light-shielding walls 1105c and 1106d. Of the light emitted by the light-emitting element 202, the light that passes through the diaphragm 209 and directly reaches the light-reflecting surface 1701, and the light that is reflected by the light-reflecting surface 1701 and directly reaches the light-receiving element 204 is detected as a displacement signal representing the displacement amount of the diaphragm 206. However, when light reflected by the light-shielding walls 1105c and 1106d passes through the diaphragm 209 and reaches the light-receiving element 204, it becomes noise in the displacement signal. In order to reduce such noise, a convex portion 1105e is formed on the lower holding member 1105, and a convex portion 1106e is formed on the upper holding member 1106.

[0130] First, the convex portion 1105e will be described. The convex portion 1105e has two surfaces. The ridge formed by the two surfaces is referred to as ridge 1105f. The cross section of the convex portion 1105e is triangular. Therefore, the convex portion 1105e may be referred to as a triangular rib. The cross section of the convex portion 1105e does not have to be triangular, but may be polygonal, particularly a polygon with an odd number of vertices. Each surface of the convex portion 1105e reflects light that directly reaches the convex portion 1105e from the light-emitting element 202 in a direction different from that of the diaphragm 209. This makes it possible to prevent light blocked by the lower holding member 1105 from being reflected toward the diaphragm 209.

[0131] In a plan view of the outer surface 206a of the diaphragm 206 (the state of FIG. 18(b)), the convex portion 1105e extends between the diaphragm 209 and the light-emitting element 202. Specifically, in this plan view, a ridge line 1105f of the convex portion 1105e extends between the diaphragm 209 and the light-emitting element 202. In a plan view of the outer surface 206a of the diaphragm 206 (the state of FIG. 18(b)), a width 1105g of the convex portion 1105e is larger than a width 209a of the diaphragm 209. This ensures that light reflected at a portion of the lower holding member 1105 between the diaphragm 209 and the light-emitting element 202 is deflected away from the diaphragm 209.

[0132] Next, the convex portion 1106e will be described. The convex portion 1106e has two surfaces. The ridge formed by the two surfaces is referred to as ridge 1106f. The cross section of the convex portion 1106e is triangular. Therefore, the convex portion 1106e may be referred to as a triangular rib. The cross section of the convex portion 1106e does not have to be triangular, but may be polygonal, particularly a polygon with an odd number of vertices. Each surface of the convex portion 1106e reflects light that directly reaches the convex portion 1106e from the light-emitting element 202 in a direction different from that of the diaphragm 209. This makes it possible to prevent light blocked by the upper holding member 1106 from being reflected toward the diaphragm 209.

[0133] In a plan view of the outer surface 206a of the diaphragm 206 (the state of FIG. 18(d)), the convex portion 1106e extends between the diaphragm 209 and the light-emitting element 202. Specifically, in this plan view, a ridge line 1106f of the convex portion 1106e extends between the diaphragm 209 and the light-emitting element 202. In a plan view of the outer surface 206a of the diaphragm 206 (the state of FIG. 18(d)), a width 1106g of the convex portion 1106e is greater than a width 209a of the diaphragm 209. This ensures that light reflected at a portion of the upper holding member 1106 between the diaphragm 209 and the light-emitting element 202 is deflected away from the diaphragm 209.

[0134] In the above-described embodiment, both the convex portion 1105e and the convex portion 1106e are formed. Alternatively, only one of the convex portion 1105e and the convex portion 1106e may be formed. Even in this case, reflected light toward the diaphragm 209 can be suppressed more effectively than when neither the convex portion 1105e nor the convex portion 1106e is formed. The convex portion 1105e and the convex portion 1106e may be applied not only to the electronic auscultation device according to the second embodiment, but also to the electronic auscultation device according to the first embodiment.

[0135] 14 to 16, several modified examples of the chestpiece 1010 will be described. The explanation of each drawing in each of Fig. 14 to 16 may be the same as that of each drawing in Fig. 11, and therefore duplicated explanations will be omitted. Furthermore, duplicated explanations will be omitted for points in the modified examples that may be the same as those in the second embodiment described above.

[0136] In the modified example shown in FIG. 14, the position of the microphone 1101 differs from that described in the second embodiment shown in FIG. 11 above. The microphone 1101 is disposed at a position overlapping the optical path of light (i.e., incident light 211 and reflected light 212) traveling from the light-emitting element 202 to the light-receiving element 204 via the reflecting member 207 in a plan view of the diaphragm 206 (i.e., when viewed from the positive z-axis direction). However, the microphone 1101 is disposed above this optical path in the z-axis direction (in the positive z-axis direction), and therefore does not block this optical path. The microphone 1101 is disposed between the light-emitting element 202 and the light-receiving element 204 in the x-axis direction. The sound detection surface 1101a of the microphone 1101 faces the sealed space 1100, which faces the inner surface 206b of the diaphragm 206. By arranging microphone 1101 in the above position, the volume of sealed space 1100 can be reduced, and microphone 1101 can detect the vibration of diaphragm 206 with high accuracy.

[0137] [Modification of the chest piece configuration of the electronic stethoscope device in the second embodiment] The modified example shown in Fig. 15 differs from the second embodiment described above in Fig. 11 in that the chestpiece 1010 further includes a light-transmitting member 1501. The light-transmitting member 1501 has the property of transmitting light emitted by the light-emitting element 202. For example, the light-transmitting member 1501 is made of glass, acrylic, polystyrene, or the like.

[0138] 15 , the hole 1104a of the base holding member 1104 is sealed by the light-transmitting member 1501 and the lower holding member 1105. Therefore, a sealed space 1502 is defined by the diaphragm 206, the base holding member 1104, the lower holding member 1105, the light-transmitting member 1501, the microphone 1101, and the sealing member 1102. The inner surface 206b of the diaphragm 206 faces this sealed space 1502. On the other hand, the light-emitting element 202 and the light-receiving element 204 do not face this sealed space 1502. In this modification, the sound detection surface 1101a of the microphone 1101 also faces the sealed space 1502, which faces the inner surface 206b of the diaphragm 206.

[0139] Light-transmitting member 1501 is disposed on the optical path of light (i.e., incident light 211 and reflected light 212) traveling from light-emitting element 202 to light-receiving element 204 via reflecting member 207. However, because light-transmitting member 1501 is light-transmitting, displacement detection unit 1011 can still detect the displacement of diaphragm 206. Furthermore, because the volume of sealed space 1502 is smaller than the volume of sealed space 1100, microphone 1101 can detect the vibration of diaphragm 206 with even greater accuracy.

[0140] [Another modified example of the chest piece configuration of the electronic auscultation device in the second embodiment] The modified example shown in FIG. 16 differs from the embodiment shown in FIG. 14 above in the position of microphone 1101 and in that chestpiece 1010 further includes light-transmitting members 1601 and 1602. Microphone 1101 is disposed at a position overlapping the optical path of light (i.e., light combining incident light 211 and reflected light 212) traveling from light-emitting element 202 to light-receiving element 204 via reflecting member 207 in a plan view of diaphragm 206 (i.e., when viewed from the positive z-axis direction). Because microphone 1101 is disposed above this optical path (in the positive z-axis direction), it does not block this optical path. For example, microphone 1101 may be disposed between light-emitting element 202 and light-receiving element 204 in three-dimensional space.

[0141] The light-transmitting members 1601 and 1602 have the property of transmitting light emitted by the light-emitting element 202. For example, the light-transmitting members 1601 and 1602 are made of glass, acrylic, polystyrene, or the like.

[0142] 16, the gap between the light-shielding wall 1106d and the light-shielding wall 1105c that constitute the diaphragm 209 on the incident light side is sealed by a light-transmitting member 1601. Furthermore, the diaphragm 210 on the reflected light side (the gap between the upper holding member 1106 and the lower holding member 1105) is sealed by a light-transmitting member 1602. Therefore, a sealed space 1603 is defined by the diaphragm 206, the base holding member 1104, the lower holding member 1105, the light-transmitting member 1601, the light-transmitting member 1602, the microphone 1101, and the sealing member 1102. The inner surface 206b of the diaphragm 206 faces the sealed space 1603. On the other hand, the light-emitting element 202 and the light-receiving element 204 do not face the sealed space 1603. In the modification shown in FIG. 16, the sound detection surface 1101 a of the microphone 1101 also faces the sealed space 1603 that faces the inner surface 206 b of the diaphragm 206 .

[0143] Light-transmitting member 1601 is disposed on the optical path of light traveling from light-emitting element 202 to reflecting member 207 (i.e., incident light 211). Light-transmitting member 1601 is disposed on the optical path of light traveling from reflecting member 207 to light-receiving element 204 (i.e., reflected light 212). However, because light-transmitting members 1601 and 1602 are light-transmitting, displacement detection unit 1011 can still detect the displacement of diaphragm 206. Furthermore, because the volume of sealed space 1603 is smaller than the volume of sealed space 1100, microphone 1101 can detect the vibration of diaphragm 206 with even greater accuracy. In this embodiment, an example has been described in which chestpiece 1010 includes both light-transmitting member 1601 and light-transmitting member 1602, but a configuration including only one of them is also possible.

[0144] [Relationship between the volume of the sealed space in the chestpiece of the electronic auscultation device and the microphone sensitivity in the second embodiment] The relationship between the volume of the sealed space facing the inner surface 206b of the diaphragm 206 and the sensitivity of the microphone 1101 will be specifically described with reference to Table 3 below.

[0145] [Table 3]

[0146] Assume that the upper limit of the displacement of the operating range of diaphragm 206 (i.e., the range in which diaphragm 206 is expected to vibrate) is 1 mm. When diaphragm 206 is displaced from a flat state to this upper limit of displacement, the volume of the internal space of chestpiece 1010 changes by, for example, 680 mm. 3 is.

[0147] The volume of the internal space of the chest piece 1010 is, for example, 17005 mm 3 Therefore, the volume change rate of the internal space when the diaphragm 206 changes to its upper limit is 680 / 17005≒4%. The volume of the sealed space 1100 described in FIG. 11 is, for example, 2085 mm 3 Therefore, the volume change rate of the sealed space 1100 due to the diaphragm 206 changing to its upper limit is 680 / 2085≒33%. The volume of the sealed space 1502 described in FIG. 15 is, for example, 1021 mm 3 Therefore, the volume change rate of sealed space 1502 when diaphragm 206 moves to its upper limit is 680 / 1021 ≈ 67%. In this way, by making only a portion of the internal space of chestpiece 1010 a sealed space facing inner surface 206b of diaphragm 206, the volume change rate of this sealed space increases, and the sensitivity of microphone 1101 increases. For example, the sealed space may be defined so that the volume change rate of the sealed space when diaphragm 206 moves to the upper limit of its operating range is 30%.

[0148] [Other embodiments] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0149] <Summary of the embodiment> (Item 1) An electronic stethoscope device, comprising: a diaphragm arranged so that an outer surface thereof contacts the living body of the subject, the diaphragm having a light reflecting surface on the opposite side to the outer surface; a light source that irradiates light toward the light reflecting surface of the diaphragm; a light receiving unit that receives light emitted by the light source and reflected by the light reflecting surface and outputs a signal corresponding to the amount of the received light; Equipped with The diaphragm further has a low-reflection surface around the light-reflecting surface, the low-reflection surface having a reflectivity lower than that of the light-reflecting surface. (Item 2) 14. The electronic auscultation device according to any one of items 1 to 13, wherein the reflectivity of the low-reflectivity surface is less than 50%. (Item 3) the diaphragm is provided with a reflecting member having the light reflecting surface, The Young's modulus of the reflecting member is smaller than the Young's modulus of the diaphragm. Item 3. The electronic auscultation device according to item 1 or 2. (Item 4) the diaphragm is provided with a sheet-like reflecting member having the light reflecting surface, The thickness of the reflecting member is thinner than that of the diaphragm. Item 4. An electronic stethoscope device according to any one of items 1 to 3. (Item 5) The thickness of the diaphragm is in the range of 130 to 510 μm. Item 5. The electronic auscultation device according to item 4. (Item 6) The diaphragm is made of glass epoxy resin, The reflecting member is made of an aluminum vapor deposition film. Item 6. The electronic auscultation device according to item 4 or 5. (Item 7) The electronic auscultation device further includes a holding member that holds the light source and the light receiving unit, 7. The electronic stethoscope device according to any one of items 1 to 6, wherein the reflectance of the portion of the holding member facing the same space as the light reflecting surface is lower than the reflectance of the light reflecting surface. (Item 8) 8. The electronic auscultation device according to any one of items 1 to 7, wherein the light reflecting surface is located at a position where light emitted by the light source directly reaches. (Item 9) the light source is a light emitting diode; 9. The electronic auscultation device according to any one of items 1 to 8, wherein the light receiving unit is composed of one light receiving element. (Item 10) The electronic stethoscope device further includes a light-shielding wall having an aperture formed thereon for passing a portion of the light emitted by the light source; Item 10. An electronic auscultation device according to item 9, wherein the light-shielding wall is formed with a convex portion having a surface that reflects light that reaches directly from the light source in a direction different from the diaphragm. (Item 11) Item 11. The electronic auscultation device according to item 10, wherein, in a plan view of the outer surface of the diaphragm, the convex portion extends between the diaphragm and the light source. (Item 12) Item 12. The electronic auscultation device according to item 11, wherein the width of the convex portion is greater than the width of the aperture in a plan view of the outer surface of the diaphragm. (Item 13) 13. The electronic auscultation device according to any one of items 1 to 12, further comprising a sound output means for outputting biological sounds emitted from the target living body based on a signal representing the displacement of the diaphragm output by the light receiving unit. (Item 14) 14. An electronic auscultation device according to any one of items 1 to 13, wherein the center of the portion of the light reflecting surface that reflects light that reaches the light receiving unit moves closer to the light source as the displacement of the diaphragm increases. (Item 15) 15. The electronic stethoscope device according to any one of items 1 to 14, wherein the center of the light reflecting surface is closer to the light source than the center of the diaphragm. (Item 16) A diaphragm displacement detection device, a diaphragm arranged so that an outer surface thereof contacts the living body of the subject, the diaphragm having a light reflecting surface on the opposite side to the outer surface; a light source that irradiates light toward the light reflecting surface of the diaphragm at a predetermined angle of incidence; a light receiving unit that receives light emitted by the light source and reflected by the light reflecting surface and outputs a signal corresponding to the amount of the received light; Equipped with The diaphragm displacement detection device, wherein the diaphragm further has a low-reflection surface around the light-reflecting surface, the low-reflection surface having a reflectance lower than that of the light-reflecting surface.

[0150] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0151] 100 Electronic stethoscope device, 110 Chest piece, 202 Light emitting element, 204 Light receiving element, 206 Diaphragm, 207 Reflecting member

Claims

1. An electronic stethoscope device, comprising: a diaphragm arranged so that an outer surface thereof contacts the living body of the subject, the diaphragm having a light reflecting surface on the opposite side to the outer surface; a light source that irradiates light toward the light reflecting surface of the diaphragm; a light receiving unit that receives light emitted by the light source and reflected by the light reflecting surface and outputs a signal corresponding to the amount of the received light; Equipped with The diaphragm further has a low-reflection surface around the light-reflecting surface, the low-reflection surface having a reflectivity lower than that of the light-reflecting surface.

2. The electronic auscultation device of claim 1 , wherein the reflectivity of the low-reflectivity surface is less than 50%.

3. the diaphragm is provided with a reflecting member having the light reflecting surface, The Young's modulus of the reflecting member is smaller than the Young's modulus of the diaphragm.

10. The electronic auscultation device of claim 1.

4. the diaphragm is provided with a sheet-like reflecting member having the light reflecting surface, The thickness of the reflecting member is thinner than that of the diaphragm.

10. The electronic auscultation device of claim 1.

5. The thickness of the diaphragm is in the range of 130 to 510 μm.

5. The electronic auscultation device according to claim 4.

6. The diaphragm is made of glass epoxy resin, The reflecting member is made of an aluminum vapor deposition film.

5. The electronic auscultation device according to claim 4.

7. The electronic auscultation device further includes a holding member that holds the light source and the light receiving unit, The electronic auscultation device according to claim 1 , wherein the reflectance of the portion of the holding member facing the same space as the light reflecting surface is lower than the reflectance of the light reflecting surface.

8. The electronic auscultation device according to claim 1 , wherein the light reflecting surface is located at a position where the light emitted by the light source directly reaches.

9. the light source is a light emitting diode; The electronic auscultation device according to claim 1 , wherein the light receiving section is composed of one light receiving element.

10. The electronic stethoscope device further includes a light-shielding wall having an aperture formed thereon for passing a portion of the light emitted by the light source; 10. The electronic auscultation device according to claim 9, wherein said light-shielding wall is formed with a convex portion having a surface that reflects light that has directly reached said light source in a direction different from that of said diaphragm.

11. The electronic auscultation device according to claim 10 , wherein the convex portion extends between the diaphragm and the light source in a plan view of the outer surface of the diaphragm.

12. The electronic auscultation device according to claim 11 , wherein the width of the convex portion is greater than the width of the aperture in a plan view of the outer surface of the diaphragm.

13. 2. The electronic auscultation device according to claim 1, further comprising a sound output unit that outputs a biological sound emitted from the subject's living body based on a signal representing the displacement of the diaphragm output by the light receiving unit.

14. 2. The electronic auscultation device according to claim 1, wherein the center of the portion of the light reflecting surface that reflects the light reaching the light receiving unit moves closer to the light source as the displacement of the diaphragm increases.

15. The electronic auscultation device according to claim 1 , wherein the center of the light reflecting surface is closer to the light source than the center of the diaphragm.

16. A diaphragm displacement detection device, a diaphragm arranged so that an outer surface thereof contacts the living body of the subject, the diaphragm having a light reflecting surface on the opposite side to the outer surface; a light source that irradiates light toward the light reflecting surface of the diaphragm; a light receiving unit that receives light emitted by the light source and reflected by the light reflecting surface and outputs a signal corresponding to the amount of the received light; Equipped with The diaphragm displacement detection device, wherein the diaphragm further has a low-reflection surface around the light-reflecting surface, the low-reflection surface having a reflectance lower than that of the light-reflecting surface.

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