Electronic auscultation device

Abstract

Appropriate output of vibration measured by optical sensor.SOLUTION: The electronic stethoscope includes a diaphragm which is brought into contact with an object to be measured and is provided with a light reflecting part on a surface opposite to a contact surface, a light emitting diode, a light receiving element which receives light regularly reflected by the light reflecting part after passing through a diaphragm part and an output part which outputs a signal formed by the regularly reflected light reaching the light receiving surface. The diaphragm is elastically deformed by being pressed by the object to be measured, the boundary line between the light irradiation region on the light receiving surface formed by the light regularly reflected by the diaphragm and the diaphragm is moved according to the displacement of the contact surface by the elastic deformation of the diaphragm, and the area of the light irradiation region on the light receiving surface is changed, and the output of the output unit is changed. A length L1 of the boundary line when the contact surface is displaced by the first displacement amount satisfies a relationship of L1 <L2 with respect to a length L2 of the boundary line when the contact surface is displaced by a larger second displacement amount.SELECTED DRAWING: FIG. 3E

Description

[Technical Field]

[0001] The present invention relates to an electronic auscultation device. [Background technology]

[0002] Electronic auscultation devices for acquiring vibration sounds based on 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. Typical biological vibrations that serve as input information for stethoscopes include biological vibrations associated with the heartbeat and biological vibrations associated with breathing, and when comparing the amplitudes of these, breathing sounds are smaller. In particular, with electronic stethoscopes that have a wide detectable frequency range, such as from 10 Hz to 2 kHz, the difference in amplitude becomes very large. [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] The diaphragm of an electronic auscultation device elastically deforms when pressed by the object being measured. The greater the displacement of the diaphragm, the greater the force the object being measured receives from the diaphragm, resulting in a smaller amplitude of the sound from the object being measured. Therefore, when the force pressing the electronic auscultation device against the object being measured is large, the amplitude of the sound from the object being measured decreases, and the sound signal output from the electronic auscultation device also decreases. Some aspects of the present invention provide a technology for appropriately outputting vibrations measured using an optical sensor. [Means for solving the problem]

[0005] According to one embodiment, there is provided a diaphragm that contacts the object to be measured, the diaphragm having a light reflection portion provided on a surface opposite to the contact surface that contacts the object to be measured; a light emitting diode; an aperture portion that restricts the light emitted from the light emitting diode; a light receiving element having a light receiving surface that receives the light that has passed through the aperture portion and is specularly reflected by the light reflection portion; and an output means that outputs a signal corresponding to the light in the light irradiation region formed by the specularly reflected light that has reached the light receiving surface. The diaphragm is configured to elastically deform under the pressure exerted by the object to be measured contacting the contact surface. A boundary line between the light irradiation region and a region other than the light irradiation region on the light receiving surface, which is formed by the light restricted by the aperture portion and specularly reflected by the light reflection portion, moves in accordance with the displacement of the contact surface due to the elastic deformation of the diaphragm. As a result, the area of the light irradiation region on the light receiving surface changes and the output of the output means changes. When the length of the boundary line when the contact surface is displaced by a first displacement amount under the pressure exerted by the object to be measured is L1, and the length of the boundary line when the contact surface is displaced by a second displacement amount greater than the first displacement amount under the pressure exerted by the object to be measured is L2, an electronic stethoscope is provided that satisfies the relationship L1 < L2.

Effect of the Invention

[0006] According to the above embodiment, the vibration measured using the optical sensor can be appropriately output.

Brief Description of the Drawings

[0007] [Figure 1A] Schematic diagram for explaining an external appearance example of the electronic stethoscope of the first embodiment. [Figure 1B] Schematic diagram for explaining an external appearance example of the electronic stethoscope of the first embodiment. [Figure 2] Schematic diagram for explaining a configuration example of the chest piece of the first embodiment. [Figure 3A] Schematic diagram for explaining an operation example of the chest piece of the first embodiment. [Figure 3B]5A to 5C are schematic diagrams illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3C] 5A to 5C are schematic diagrams illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3D] 5A to 5C are schematic diagrams illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3E] 5A and 5B are schematic diagrams illustrating an example of change in the light receiving range according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the relationship between the displacement amount and the displacement signal according to the first embodiment. [Figure 5] 1 is a block diagram illustrating an example of the configuration of an electronic auscultation device according to a first embodiment. [Figure 6A] FIG. 4 is a schematic diagram illustrating a first modified example of the chestpiece of the first embodiment. [Figure 6B] FIG. 4 is a schematic diagram illustrating a first modified example of the chestpiece of the first embodiment. [Figure 6C] FIG. 10 is a schematic diagram illustrating a second modified example of the chestpiece of the first embodiment. [Figure 6D] FIG. 10 is a schematic diagram illustrating a second modified example of the chestpiece of the first embodiment. [Figure 6E] 10A and 10B are schematic diagrams illustrating an example of change in the light receiving range of the second modified example. [Figure 6F] FIG. 10 is a schematic diagram illustrating a third modified example of the chestpiece of the first embodiment. [Figure 6G] FIG. 10 is a schematic diagram illustrating a third modified example of the chestpiece of the first embodiment. [Figure 6H] 10A and 10B are schematic diagrams illustrating an example of change in the light receiving range of the third modified example. [Figure 6I] FIG. 10 is a diagram illustrating the relationship between the displacement amount and the displacement signal in the third modified example. [Figure 7] 5A and 5B are schematic diagrams illustrating an example of change in the light receiving range according to 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. 1A and 1B. The following drawings may be accompanied by a coordinate system CS, which is a three-dimensional Cartesian coordinate system having an x-axis, a y-axis, and a z-axis, to explain the 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. 1A shows the appearance of the electronic auscultation device 100 when viewed from one direction, and FIG. 1B shows the appearance of the electronic auscultation device 100 when viewed from another direction. The electronic auscultation device 100 is a diagnostic tool for listening to the internal sounds of a living body, such as a human or animal. The electronic auscultation device 100 is primarily used to listen to heartbeats and breathing sounds.

[0010] As shown in FIG. 1A, the electronic auscultation device 100 includes a chestpiece 110 and a grip 120. The chestpiece 110 is a unit that is brought into contact with the surface of a living body, which is an example of a subject to be measured, during diagnosis using the electronic auscultation device 100, to measure minute vibrations (displacements) on the surface of the living body and capture biological sounds. The chestpiece 110 detects minute displacements on the surface of the living body in close contact with the chestpiece 110 via a diaphragm 206 (described later). Therefore, the chestpiece 110 can also be referred to as a displacement detection device or a diaphragm displacement detection device. Furthermore, because the chestpiece 110 is used to detect vibrations on the surface of the living body, it can also be referred to as a biological vibration detection device.

[0011] The gripping portion 120 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. The gripping portion 120 is rod-shaped as shown in FIGS. 1A and 1B, and the chestpiece 110 is attached to one end (the negative x-axis direction in FIGS. 1A and 1B). The gripping portion 120 is also called a handle, a grip, a handle, or the like.

[0012] The grip part 120 has a housing 121. The grip part 120 houses a battery and a circuit board inside the 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 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 includes multiple indicators (four indicators in the example of FIG. 1A ). 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. 1A , 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. In this embodiment, "near the chestpiece 110" means that the display unit 122 is closer to the chestpiece 110 than the center of the grip portion 120. The display unit 122 does not need to include all of the indicators described above, and the status of the electronic auscultation device 100 may be displayed using 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. 1A) for accepting settings for the electronic auscultation device 100. 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 earphones. 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. That is, the mode switching button 123c accepts instructions from the user regarding the mode transition of the electronic auscultation device 100. The electronic auscultation device 100 selects one of multiple operation modes based on an instruction from the user using the mode switching button 123c and operates in that operation mode. The operation unit 123 may include a touch panel instead of multiple physical buttons. The display unit 122 and operation unit 123 may be integrated as a touch screen. The electronic auscultation device 100 may automatically select an operation mode in response to an acquired signal representing vibrations on the surface of a living body, instead of or in addition to a user's instruction using the mode switching button 123c.

[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 light reflecting portion 207 are shown to clarify the positional relationship of the components.

[0019] The chestpiece 110 includes 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 light-reflecting portion 207, and a housing 208. The housing 208 houses the holding member 201, the light-emitting element 202, the light-emitting circuit board 203, the light-receiving element 204, the light-receiving circuit board 205, and the light-reflecting portion 207. Because the holding member 201 has apertures 209 and 210, the housing 208 also houses the apertures 209 and 210. The diaphragm 206, together with the housing 208, form part of the exterior of the electronic auscultation device 100. Note that the components of the chestpiece 110 described here are merely examples, and in addition to the components shown in FIG. 2 , the chestpiece 110 may also include a circuit board on which circuit elements for controlling its operation 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 (a battery in the grip portion 120). In this embodiment, the light emitting element 202 uses a light emitting diode (LED).

[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, or may be a paper phenol board or a glass epoxy 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 functions as an optical sensor that 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 is supplied from a power source external to the chestpiece 110 (e.g., a battery in the grip portion 120). 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 elements 204 is one, but the present invention is not limited to this. A line sensor (light receiving elements arranged in a 1×n (n≧2)) or an area sensor (light receiving elements arranged in an m×n (m≧2, n≧2)) may be configured using a plurality of 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, the light receiving circuit board 205 is also mounted with peripheral circuits for reading out signals from the light receiving element 204, a signal terminal for outputting signals to a device external to the chest piece 110, and a power supply terminal for receiving power from a power source external to the chest piece 110. The light receiving circuit board 205 may be a printed wiring board such as a flexible circuit board, or may be a paper phenolic board or a glass epoxy 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 diaphragm 206 has a contact surface 206a that contacts the surface of a living body, which is an example of a measurement target, and an inner surface 206b that is the surface opposite the contact surface 206a. The diaphragm 206 is configured to elastically deform when pressed by the measurement target contacting the contact surface 206a. The inner surface 206b of the diaphragm 206 is provided with a light reflecting portion 207, which will be described later. In this embodiment, the diaphragm 206 is a laminated plate of glass epoxy resin, which is made by impregnating glass fiber with epoxy resin and then subjecting it to a thermal curing treatment. The thickness is 230 μm. The diaphragm 206 also has an integrated ring-shaped rim for fixing the diaphragm 206 to the holding member 201 or the housing 208. In this embodiment, the contact surface 206a and inner surface 206b of the diaphragm 206 refer to the portions of the diaphragm 206 that do not include the ring-shaped rim integrated with the diaphragm 206. The diaphragm 206 may have a multi-layer structure. In this case, the outermost layer of the multi-layered diaphragm 206 that contacts the object to be measured is defined as the contact surface 206a, and the innermost layer on which the light reflecting portion 207 is provided is defined as the inner surface 206b. The diaphragm 206 may be composed of multiple layers or members as long as it vibrates integrally with the object to be measured when it contacts it. In this embodiment, even if a separate cover is attached to the contact surface 206, this configuration is considered to be one form of the diaphragm 206 as long as the cover and the contact surface 206a vibrate integrally with the object to be measured. Furthermore, the contact surface 206a of the diaphragm 206 is exposed to the outside when the electronic auscultation device 100 is in use, but may be covered with a protective cover when not in use to prevent damage or deterioration to the contact surface 206a.

[0026] The diaphragm 206 is held by the holding member 201. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 is arranged so as to contact the surface of a living body, which is an example of a measurement target. The diaphragm 206 forms part of the exterior of the chestpiece 110. The diaphragm 206 has a contact surface 206a arranged so as to contact the surface of a living body when the electronic auscultation device 100 is in use, and an inner surface 206b opposite the contact surface 206a.

[0027] Diaphragm 206 has fixed portion 206c and is fixed to holding member 201. Fixed portion 206c is located on the outer periphery of diaphragm 206. The inner periphery of diaphragm 206 (i.e., the portion inside fixed portion 206c) is not fixed to holding member 201. Therefore, diaphragm 206 can vibrate in the z-axis direction with fixed portion 206c as a node. Specifically, when chestpiece 110 is in use, diaphragm 206 vibrates with fixed portion 206c as a node in response to displacement of the surface of the living body. In this vibration, center 206e of diaphragm 206 becomes an antinode. Diaphragm 206 functions as a vibrating part that vibrates together with the object to be measured.

[0028] The light reflecting portion 207 reflects light emitted from the light emitting element 202. The light reflecting portion 207 is adhered to the inner surface 206b of the diaphragm 206 and moves integrally with the diaphragm 206 in the z-axis direction in response to the vibration of the diaphragm 206, which is in close contact with the surface of the living body. The light reflecting portion 207 has a circular outer edge in a plan view. The light reflecting portion 207 may have a diameter of 15 mm to 20 mm. The light reflecting portion 207 is disposed in a position covering an area 206d of the diaphragm 206 that includes a center 206e of the circle. 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 area including the center 206e. Note that, although the light reflecting portion 207 is disposed in a position covering the center 206e in this embodiment, it may also be disposed in a position covering an area of ​​the diaphragm 206 that does not include the center 206e. The light reflecting portion 207 is made of, for example, an aluminum vapor deposition film, and is a sheet-like member attached to the inner surface 206b of the diaphragm 206 (the surface opposite to the contact surface 206a).

[0029] The light emitting element 202 emits light toward the inner surface 206b of the diaphragm 206. The upper surface of the light reflecting portion 207 reflects the light emitted from the light emitting element 202. That is, the upper surface of the light reflecting portion 207 functions as a light reflecting surface. In the following description, the reflection of light on the upper surface (i.e., the light reflecting surface) of the light reflecting portion 207 will simply be referred to as light being reflected by the light reflecting portion 207. The light reflecting portion 207 specularly reflects (in other words, specularly reflects) the light emitted from the light emitting element 202. In the following description, the light traveling from the light emitting element 202 toward the light reflecting portion 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.

[0030] In this embodiment, the light reflecting portion 207 is a separate member from the diaphragm 206. However, the light reflecting portion 207 may be configured as the same member as the diaphragm 206, with at least a portion of the inner surface 206b of the diaphragm 206 also serving as the light reflecting portion. Alternatively, a coating layer may be applied to the diaphragm 206, and the coating layer may be configured as the light 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, which is reached by light emitted from the light emitting element 202, may have such a high reflectivity.

[0031] The light-emitting element 202 is disposed so as to emit light toward a region 207a of the light-reflecting portion 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. In this embodiment, as described above, an LED that emits diffused light is used as the light-emitting element 202. Therefore, the chestpiece 110 has an aperture portion 209 that narrows the light emitted from the light-emitting element 202. The aperture portion 209 allows only a portion of the light emitted from the light-emitting element 202 to enter the light-reflecting portion 207. In the example of FIG. 2, the aperture portion 209 corresponds to a portion of the holding member 201 where an opening is formed. Note that in this embodiment, a component that emits diffused light has been described as an example of the light-emitting element 202. However, instead, a laser diode or the like that emits linear light may be used as the light-emitting element 202, and the linear light may be emitted toward the region 207a. If the light emitting element 202 is a component that emits linear light, the diaphragm portion 209 may be omitted. In the present embodiment, the portion of the holding member 201 where the opening is formed has been described as an example of the diaphragm portion 209, but a one-sided diaphragm may be used instead of an opening. In that case, for example, a light blocking wall for narrowing down one side (upper or lower side) of the light emitted from the light emitting element 202 is provided instead of the opening.

[0032] 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 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 based on this electrical signal. The principle behind this can be described later. The chestpiece 110 has an aperture 210 that narrows the light specularly reflected by the light reflecting portion 207. The diaphragm section 210 prevents diffusely reflected light from entering the light receiving element 204, and allows only at least a portion of the light from the light reflecting section 207 (i.e., the primarily reflected light) to reach the light receiving element 204. In the example of FIG. 2, the portion of the holding member 201 where the opening is formed functions as the diaphragm section 210. In this embodiment, the portion of the holding member 201 where the opening is formed has been described as an example of the diaphragm section 210, but a one-sided diaphragm may be used instead of an opening. In that case, for example, a light-shielding wall for narrowing down one side (upper or lower side) of the light from the light reflecting section 207 is provided instead of the opening.

[0033] A housing 208 is attached to the outer periphery 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 are all substantially aligned with one another in a plan view of the contact surface 206a of the diaphragm 206. In this embodiment, the housing 208 is made of metal, and the grounds of the circuit boards (e.g., the light-emitting circuit board 203 and the light-receiving circuit board 205) inside the chestpiece 110 are electrically connected to the housing 208. This stabilizes the ground potential.

[0034] By fixing the diaphragm 206 to the holding member 201, an internal space 213 surrounded by the diaphragm 206 and the holding member 201 is formed. 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 and the holding member 201 have 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. In the example of FIG. 2, a fixed portion 206c of the diaphragm 206 is fixed to the holding member 201. Alternatively, in the example of FIG. 2, the fixed portion 206c of the diaphragm 206 may be fixed to the housing 208.

[0035] [Example of operation of the electronic auscultation device in the first embodiment] The operation of the chestpiece 110 of the electronic auscultation device 100 will be described with reference to Figures 3A to 3D. Figures 3A and 3B show a state in which the diaphragm 206 is not pressed by the biological surface 320 (hereinafter referred to as the "flat state"), while Figures 3C and 3D show a state in which the diaphragm 206 is pressed by the biological surface 320. In each of Figures 3A and 3C, the lower side shows a cross-sectional view of the chestpiece 110, and the upper side shows a plan view of the chestpiece 110. The cross-sectional view of the chestpiece 110 omits the light-emitting circuit board 203, the light-receiving circuit board 205, and the housing 208, and shows the shape of the holding member 201 in detail. The plan view of the chestpiece 110 shows only the light-emitting element 202, the light-receiving element 204, the light-reflecting portion 207, the light-shielding wall 304, and the light-shielding wall 305. 3B and 3D are perspective views focusing on the light emitting element 202, the light receiving element 204, the light reflecting portion 207, the light shielding wall 304, and the light shielding wall 305. FIG.

[0036] As shown in FIGS. 3A to 3D, the chestpiece 110 is used in contact with a biological surface 320, which is an example of a subject to be measured. That is, during use, the contact surface 206a of the diaphragm 206 of the chestpiece 110 is in close contact with the biological surface 320, which is an example of a subject to be measured. This causes the biological surface 320, diaphragm 206, and light reflecting portion 207 to vibrate together. Therefore, the chestpiece 110 detects the displacement of the upper surface of the light reflecting portion 207 in the z-axis direction as the displacement of the biological surface 320 in the z-axis direction. The displacement of the biological surface 320 occurs in response to the physical movements of the person owning the biological surface 320, such as heartbeat and breathing.

[0037] The chestpiece 110 has a light blocking member 302. The light blocking member 302 is fixed so as to contact the light receiving surface of the light receiving element 204. An opening 302a is formed in the light blocking member 302. The light blocking member 302 covers a portion of the light receiving surface of the light receiving element 204. The portion of the light receiving surface of the light receiving element 204 that overlaps with the opening 302a faces the internal space 213. Therefore, the light receiving element 204 can detect only light that passes through the opening 302a and reaches the light receiving surface.

[0038] The shape of the opening 302a is trapezoidal. Two of the four sides of the opening 302a are parallel to the diaphragm 206 (e.g., its contact surface 206a) in a flat state. Of the four sides of the opening 302a, the side parallel to the diaphragm 206 and closer to the diaphragm 206 is referred to as the lower side, the side parallel to the diaphragm 206 and farther from the diaphragm 206 is referred to as the upper side, the side on the left side as viewed from the light-emitting element 202 is referred to as the left side, and the side on the right side as viewed from the light-emitting element 202 is referred to as the right side. The lower side of the opening 302a is shorter than the upper side of the opening 302a. Therefore, the width of the opening 302a in a first plane parallel to the diaphragm 206 is smaller than the width of the opening 302a in a second plane parallel to the diaphragm 206 and farther from the diaphragm 206 than the first plane.

[0039] 3A and 3B, the light-emitting element 202 and the light-receiving element 204 are arranged 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 to generate an output value as a displacement signal, converts the displacement signal into a digital signal, and outputs it to an external device. In this embodiment, the displacement signal refers to the output value of the light-receiving element 204 that reflects the state and deformation of the diaphragm 206 at any given time.

[0040] 3C and 3D, when the diaphragm 206 is pressed by the biological surface 320 and the biological surface 320 is displaced upward, the distance in the z-axis direction between the light-emitting element 202 and the upper surface of the light reflecting portion 207 decreases. Accordingly, the area of ​​the light reflecting portion 207 that is reached by 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. As a result, the amount of reflected light 212 that reaches the light-receiving element 204 decreases, and the value of the displacement signal generated by the light-receiving circuit board 205 decreases.

[0041] In the chestpiece 110 of FIGS. 3A to 3D, the light-shielding wall 304 in which the opening 306 is formed functions as the diaphragm section 209 on the incident light 211 side, and the light-shielding wall 305 in which the opening 307 is formed functions as the diaphragm section 210 on the reflected light 212 side. In particular, the portion of the light-shielding wall 304 above the upper edge of the opening 306 corresponds to the first diaphragm section. Therefore, part of the light emitted by the light-emitting element 202 is blocked by the light-shielding wall 304 and does not reach the light-reflecting section 207. Furthermore, at least part of the light specularly reflected by the light-reflecting section 207 is blocked by the light-shielding wall 305 depending on the position of the light-reflecting section 207. In this embodiment, the openings 306 and 307 are rectangular in shape. In the following description, of the four sides of each of openings 306 and 307, the side parallel to and closer to diaphragm 206 will be referred to as the bottom side, the side parallel to and farther from diaphragm 206 will be referred to as the top side, the side to the left as viewed from light-emitting element 202 will be referred to as the left side, and the side to the right as viewed from light-emitting element 202 will be referred to as the right side.

[0042] 3A to 3D, incident light 211 and reflected light 212 represent light fluxes that reach light receiving element 204. In Fig. 3B, part of the light emitted from light emitting element 202, light 310, passes through opening 306 of light-shielding wall 304 and is reflected by light reflecting portion 207 to become light 311, but is blocked by a portion of light-shielding wall 305 that is above reflected light 212 and does not reach light receiving element 204. The same is true in Fig. 3D.

[0043] 3A and 3B, the portion of the light reflecting portion 207 that is reached by the incident light 211 when the diaphragm 206 is in a flat state is referred to as the effective range 300. The effective range 300 is the portion of the light reflecting portion 207 that reflects light that reaches the light receiving element 204. When the diaphragm 206 is in a flat state, the effective range 300 is equal to the range reached by the light from the light emitting element 202. In this embodiment, the effective range 300 is a trapezoidal region. The outer periphery of the effective range 300 is referred to as the boundary line of the effective range 300. The boundary line of the effective range 300 is located between the effective range 300 and the area other than the effective range 300. In the following description, part of the boundary line will also be referred to as the boundary line.

[0044] Of the four line segments that form the boundary of the effective range 300, the line segment that includes the farthest position in the x-axis direction from the light-emitting element 202 is referred to as the far boundary line 300a. The portion of the incident light 211 that reaches the far boundary line 300a is referred to as the far incident light 211a. The far incident light 211a means that it includes the portion of the optical path from the light-emitting element 202 to the light reflecting unit 207 that is the longest. The angle of incidence of the incident light 211 to the light reflecting unit 207 reaches a maximum value 303a at a position on the far boundary line 300a.

[0045] Of the four line segments that form the boundary of the effective range 300, the line segment that includes the position closest to the light-emitting element 202 in the x-axis direction is referred to as the near boundary line 300b. The portion of the incident light 211 that reaches the near boundary line 300b is referred to as the near incident light 211b. The near incident light 211b means that it includes the portion of the optical path from the light-emitting element 202 to the light reflecting portion 207 that is shortest. The angle of incidence of the incident light 211 to the light reflecting portion 207 reaches a minimum value 303b at a position on the near boundary line 300b. 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 light-shielding wall 304.

[0046] Of the four line segments that make up the boundary of effective range 300, the two line segments other than far boundary 300a and near boundary 300b are referred to as lateral boundary lines 300c and 300d. Lateral boundary line 300c is located on the right side of effective range 300 as seen from light-emitting element 202, and lateral boundary line 300d is located on the left side of effective range 300 as seen from light-emitting element 202.

[0047] As shown in FIGS. 3A and 3B , the region of the light receiving element 204 formed by the reflected light 212 specularly reflected by the light reflecting portion 207 is referred to as the light irradiation region 301. The light irradiation region 301 is a portion of the light receiving element 204 where light emitted from the light emitting element 202 and specularly reflected by the light reflecting portion 207 reaches. In addition to the light specularly reflected by the light reflecting portion 207, scattered light may also reach the light receiving element 204. In this embodiment, the region formed by the specularly reflected light is defined as the light irradiation region. The amount of light reaching the light receiving element 204 is proportional to the area of ​​the light irradiation region 301. In this embodiment, the light irradiation region 301 is a trapezoidal region. The periphery of the light irradiation region 301 is referred to as the boundary line of the light irradiation region 301. The boundary line of the light irradiation region 301 is located between the light irradiation region 301 and the region other than the light irradiation region 301.

[0048] Of the four line segments constituting the boundary of the light irradiation area 301, the line segment formed by light that has been narrowed by the aperture section 209 and specularly reflected by the light reflecting section 207 is referred to as the lower boundary 301a. Of the four line segments constituting the boundary of the light irradiation area 301, the line segment opposite the lower boundary 301a is referred to as the upper boundary 301b. The lower boundary 301a is an example of a boundary formed by light that has been narrowed by the aperture section 209 and specularly reflected by the light reflecting section 207. The lower boundary 301a is a boundary that moves in response to the displacement of the contact surface 206a, as described below. In this embodiment, the movement of the lower boundary 301a changes the area of ​​the light irradiation area 301, and the output of the light receiving element 204 changes. This enables accurate measurement of the displacement of the object to be measured. The upper boundary 301b is an example of a boundary that does not move in response to the displacement of the contact surface 206a and whose length does not change even when the contact surface 206a is displaced. Of the four line segments that form the boundary of the light-irradiated region 301, the two line segments other than the lower boundary 301a and the upper boundary 301b are referred to as lateral boundary lines 301c and 301d. The lateral boundary line 301c is located on the right side of the light-irradiated region 301 as viewed from the light-emitting element 202, and the lateral boundary line 301d is located on the left side of the light-irradiated region 301 as viewed from the light-emitting element 202. The lateral boundary lines 301c and 301d are examples of boundary lines that do not move in response to the displacement of the contact surface 206a, but whose lengths change when the contact surface 206a is displaced, as will be described later.

[0049] Light passing through the opening 306 along the upper edge of the opening 306 is specularly reflected by the light reflecting portion 207, and then reaches the lower boundary line 301a of the light irradiation area 301 of the light receiving element 204 without being blocked by the light-shielding wall 305 or the light-shielding member 302. Therefore, the upper edge of the opening 306 defines the lower boundary line 301a of the light irradiation area 301. On the other hand, light passing through the opening 306 along the lower edge of the opening 306 is specularly reflected by the light reflecting portion 207, and then is blocked by the light-shielding wall 305 or the light-shielding member 302, and does not reach the light receiving element 204. Therefore, the lower edge of the opening 306 does not define the light irradiation area 301. Therefore, the near incident light 211b is not narrowed down by the diaphragm portion 209. Alternatively, the configuration may be such that light passing through opening 306 along the lower edge of opening 306 is specularly reflected by light reflecting portion 207 and then reaches light receiving element 204 without being blocked by light-shielding wall 305 or light-shielding member 302. In this case, the lower edge of opening 306 defines light irradiation area 301. In such a configuration, the displacement signal remains constant as the displacement of diaphragm 206 ranges from zero to a predetermined value. Thereafter, when the lower edge of opening 306 no longer defines light irradiation area 301, the displacement signal begins to decrease monotonically.

[0050] Light that passes through opening 306, is specularly reflected by light reflecting portion 207, passes through opening 307, and then passes through opening 302a along the upper edge of opening 302a reaches upper boundary line 301b of light irradiation area 301 of light receiving element 204. Therefore, the upper edge of opening 302a defines upper boundary line 301b of light irradiation area 301. On the other hand, light does not pass through the portion along the lower edge of opening 302a because it is blocked by light-shielding wall 304. Therefore, the lower edge of opening 302a does not define light irradiation area 301.

[0051] 3A, the lateral boundary lines 301c and 301d of the light irradiation area 301 are defined by the right and left sides of the opening 302a. Therefore, the ends of the lower boundary line 301a are defined by the right and left sides of the opening 302a. Alternatively, the lateral boundary lines 301c and 301d of the light irradiation area 301 may be defined by the right and left sides of the opening 306.

[0052] The reflected light of the distant incident light 211a is referred to as bottom-end reflected light 212a. The bottom-end reflected light 212a is the light of the reflected light 212 that is located lowest in the z-axis direction (i.e., the portion closest to the diaphragm 206). The bottom-end reflected light 212a reaches the lower boundary 301a of the light irradiation area 301. The lower boundary 301a is formed by light that is narrowed by the diaphragm section 209 and specularly reflected by the light reflecting section 207. The bottom-end reflected light 212a is away from each side of the opening 307 and each side of the opening 302a. In other words, the bottom-end reflected light 212a is not narrowed by the diaphragm section 210 or the light-shielding member 302. In the configurations of FIGS. 3A and 3B , the lower boundary 301a includes the position of the light irradiation area 301 that is closest to the diaphragm 206 in the normal direction (i.e., the z-axis direction) of the diaphragm 206 when the light irradiation area 301 is flat. 3A and 3B, lower boundary line 301a includes the position in light irradiation area 301 where light reaches with the maximum reflection angle at light reflecting portion 207. This maximum reflection angle is equal to maximum incident angle 303a. Furthermore, in the configurations of FIGS. 3A and 3B, lower boundary line 301a includes the position farthest from light emitting element 202 in a plan view of diaphragm 206 in a flat state.

[0053] The reflected light of the near incident light 211b is referred to as upper end reflected light 212b. The upper end reflected light 212b is the light located at the uppermost position in the z-axis direction among the reflected light 212 (i.e., the portion farthest from the diaphragm 206). The upper end reflected light 212b reaches the upper boundary line 301b of the light irradiation area 301. In the configurations of FIGS. 3A and 3B, the upper boundary line 301b includes the position in the light irradiation area 301 that is farthest from the diaphragm 206 in the normal direction of the diaphragm 206 in the flat state (i.e., the z-axis direction). Also, in the configurations of FIGS. 3A and 3B, the upper boundary line 301b includes the position in the light irradiation area 301 where the light reaches with the smallest reflection angle at the light reflecting portion 207. This minimum reflection angle is equal to the minimum incident angle 303b. Furthermore, in the configurations of FIGS. 3A and 3B, upper boundary line 301b includes the position closest to light emitting element 202 in a plan view of diaphragm 206 in a flat state.

[0054] 3C and 3D, when the diaphragm 206 is pressed by the biological surface 320, the positions of the effective range 300, the far boundary 300a, the near boundary 300b, the light irradiation region 301, the lower boundary 301a, and the upper boundary 301b all change. The portion of the reflected light 212 farthest from the light-emitting element 202 in the x-axis direction is referred to as the lower-end reflected light 212a. The lower-end reflected light 212a reaches the lower boundary 301a of the light irradiation region 301. As described above, the lower boundary 301a is defined by the upper side of the opening 306 of the diaphragm unit 209 on the light-emitting element 202 side. The lower boundary 301a moves in response to the displacement of the contact surface 206a due to the elastic deformation of the diaphragm 206. This changes the area of ​​the light irradiation region 301 and the output of the light-receiving element 204, as described below.

[0055] As shown in FIGS. 3A to 3D , the upper boundary line 301b is defined by a portion of the light-shielding wall 305 that is above the reflected light 212, and is a boundary line that does not move in response to displacement of the contact surface 206a and whose length does not change even when displacement of the contact surface 206a occurs. The portion of the light-shielding wall 304 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 304 that is below the incident light 211 does not need to be provided. Furthermore, the lower boundary line 301a is defined by a portion of the light-shielding wall 304 that is above the incident light 211. Therefore, the portion of the light-shielding member 302 that is below the reflected light 212 does not need to block the light specularly reflected by the light reflecting portion 207. For example, the portion of the light-shielding member 302 that is below the reflected light 212 does not need to be provided.

[0056] [Change in the range of reflected light in the electronic auscultation device according to the first embodiment] Referring to FIG. 3E, a change in the light irradiation area 301 formed by the reflected light 212 that reaches the light receiving surface of the light receiving element 204 will be described. FIG. 3E shows a plan view of the light receiving surface of the light receiving element 204. The left side of FIG. 3E shows the position of the light irradiation area 301 when the diaphragm 206 is in a flat state. The center of FIG. 3E shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 (first displacement amount) from the flat state due to pressure from the biological surface 320. The right side of FIG. 3E shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2 (second displacement amount) that is larger than the displacement amount d1 from the flat state due to pressure from the biological surface 320.

[0057] 3E, the effective range 300 is a trapezoidal region. Specifically, the edges of the effective range 300 are formed by a lower boundary line 301a, an upper boundary line 301b, a side boundary line 301c, and a side boundary line 301d. The lower boundary line 301a and the upper boundary line 301b are each parallel to the diaphragm 206 (e.g., its contact surface 206a) in the flat state, and the lower boundary line 301a is shorter than the upper boundary line 301b.

[0058] To explain the directions, a coordinate system CS' is attached to FIG. 3E. The coordinate system CS' is a two-dimensional Cartesian coordinate system having mutually orthogonal x'-axis and y'-axis. 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.

[0059] The surface of the light receiving element 204 that faces the internal space 213 is the light receiving surface. The light receiving element 204 detects the amount of light that reaches the light receiving surface. As described above, in this embodiment, the light receiving element 204 is a single light receiving element. A line sensor or an area sensor may be used instead of the single light receiving element. 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 the bottom side 204a.

[0060] The area of ​​the light-irradiated region 301 is determined by a lower boundary line 301a, an upper boundary line 301b, and side boundary lines 301c and 301d. As shown in FIG. 3E, the lower boundary line 301a of the light-irradiated region 301 changes in the x′-axis direction in response to the displacement of the contact surface 206a. On the other hand, the upper boundary line 301b and the side boundary lines 301c and 301d do not substantially move in response to the displacement of the contact surface 206a. Therefore, the area of ​​the light-irradiated region 301 changes in response to the movement of the lower boundary line 301a. The length of the upper boundary line 301b does not change even when the contact surface 206a is displaced. On the other hand, the lengths of the side boundary lines 301c and 301d change when the contact surface 206a is displaced.

[0061] As the area of ​​the light-irradiated region 301 changes, the signal output from the light-receiving element 204 also changes. Specifically, the greater the displacement of the contact surface 206a of the diaphragm 206 from the flat state, the shorter the distance between the lower boundary 301a and the upper boundary 301b (i.e., the lengths of the lateral boundary lines 301c and 301d), and the smaller the area of ​​the light-irradiated region 301. Therefore, the greater the displacement of the diaphragm 206 from the flat state, the less light the light-receiving element 204 receives. Accordingly, the signal output from the light-receiving element 204 also becomes smaller. As shown in FIG. 3E, the amount of movement of the lower boundary line 301a accompanying the movement of the light-reflecting portion 207 is greater than the amount of movement of the upper boundary line 301b accompanying the movement of the light-reflecting portion 207.

[0062] The length of the lower boundary line 301a changes when the contact surface 206a is displaced. Specifically, the length of the lower boundary line 301a when the diaphragm 206 is flat (left side of FIG. 3E) is defined as L0. The length of the lower boundary line 301a when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 (center of FIG. 3E) is defined as L1. The length of the lower boundary line 301a when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2 that is larger than the displacement amount d1 (right side of FIG. 3E) is defined as L2. In this case, L0 <L1<L2 Therefore, the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2.

[0063] 3E, the change in the light irradiation area 301 in the x'-axis direction is larger than the change in the light irradiation area 301 in the y'-axis direction. Therefore, in order to increase the dynamic range of the light receiving element 204, it is preferable that the width of the light receiving element 204 in the x'-axis direction be larger than the width of the light receiving element 204 in the y'-axis direction. More specifically, it is preferable that the width of the light receiving element 204 in the x'-axis direction be three or more times the width of the light receiving element 204 in the y'-axis direction.

[0064] [Relationship between the displacement amount of the living body surface and the displacement signal in the electronic auscultation device in the first embodiment] The relationship between the displacement amount of the biological surface 320 and the displacement signal will be described with reference to Fig. 4(a). The displacement signal is a voltage output from the light receiving circuit board 205. A graph 400 in Fig. 4(a) shows the relationship between the displacement amount of the biological surface 320 and the displacement signal. The horizontal axis of the graph 400 represents the displacement amount of the biological surface 320, and represents the displacement signal generated by the light receiving circuit board 205.

[0065] As described above, the displacement amount of the biological surface 320 is equal to the displacement amount of the upper surface of the light reflecting portion 207. The displacement amount of the upper surface of the light reflecting portion 207 is equal to the displacement amount of the diaphragm 206. As shown in Fig. 4(a) , as the displacement amount of the reflected light 212 increases, the light that reaches the light receiving element 204 of the reflected light 212 decreases monotonically and nonlinearly.

[0066] In graph 400, Vmax is the value of the displacement signal when the displacement d is zero. Vmax is determined by the amount of light emitted by light-emitting element 202 and the sensitivity of light-receiving element 204. The sensitivity of light-receiving element 204 refers to the amount of change in output voltage per unit amount of light incident on light-receiving element 204. Vmax increases as the sensitivity of light-receiving element 204 increases.

[0067] The displacement amount d at which the displacement signal S becomes zero is represented as dmax. dmax is, for example, 1 mm. As the displacement amount d of the biological surface 320 increases, the area of ​​the light irradiation region 301 decreases and becomes zero. When the area of ​​the light irradiation region 301 becomes zero, the displacement signal S also becomes zero. The displacement amount d at which the area of ​​the light irradiation region 301 becomes zero is determined by the respective positions of the light receiving element 204 and the diaphragm unit 210 relative to the reflected light 212.

[0068] When the displacement d exceeds dmax, reflected light 212 no longer reaches light receiving element 204, and thus displacement signal S remains zero even if the displacement d increases. Therefore, chestpiece 110 is configured so that displacement d is in the range of 0 to dmax within the range in which diaphragm 206 is expected to vibrate (referred to as the operating range of diaphragm 206). As shown in graph 400, light emitting element 202 and light receiving element 204 are positioned so that the amount of light reaching light receiving element 204 (amount of received light) changes monotonically in response to movement of light reflecting portion 207 in one direction within the operating range of diaphragm 206. In the example of FIG. 4(a), light receiving element 204 is positioned so that the amount of received light monotonically decreases; however, as described below, light receiving element 204 may also be positioned so that the amount of received light monotonically increases.

[0069] As described above, the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2. Therefore, the amount of change in the displacement signal per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the displacement signal per unit displacement of contact surface 206a of diaphragm 206 when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2.

[0070] Specifically, the amount of change in the displacement signal caused by the contact surface 206a of the diaphragm 206 being further displaced by w1 from the state where the amount of displacement is d1 is defined as w2. Also, the amount of change in the displacement signal caused by the contact surface 206a of the diaphragm 206 being further displaced by w1 from the state where the amount of displacement is d2 is defined as w3. In this case, w2 <w3 That is, the greater the displacement of the contact surface 206a of the diaphragm 206, the higher the light receiving sensitivity of the light receiving element 204.

[0071] The diaphragm 206 elastically deforms when pressed by the object to be measured that is in contact with the contact surface 206a. Therefore, the greater the displacement of the contact surface 206a of the diaphragm 206, the greater the force that the biological surface 320 receives from the diaphragm 206, and the smaller the amplitude of the biological vibration. In this embodiment, the greater the displacement of the contact surface 206a of the diaphragm 206, the higher the light receiving sensitivity of the light receiving element 204. Therefore, the amplitude of the object to be measured can be made uniform regardless of the force with which the electronic auscultation device 100 is pressed against the biological surface 320. This allows the vibration measured using the optical sensor to be output appropriately.

[0072] The relationship between the displacement of the biological surface 320 and the displacement signal in the comparative example will be described with reference to FIG. 4(b). Graph 410 in FIG. 4(b) shows the relationship between the displacement of the biological surface 320 and the displacement signal. The horizontal axis of graph 410 represents the displacement of the biological surface 320, which represents the displacement signal generated by the light-receiving circuit board 205. As shown in FIG. 4(b), as the displacement of the reflected light 212 increases, the portion of the reflected light 212 that reaches the light-receiving element 204 decreases monotonically and linearly. Therefore, regardless of the displacement of the contact surface 206a of the diaphragm 206, the change in the displacement signal resulting from a displacement of w1 of the contact surface 206a of the diaphragm 206 is always w4. Therefore, the force with which the electronic auscultation device 100 is pressed against the biological surface 320 causes variations in the amplitude of the measurement target.

[0073] In this embodiment, the light emitting element 202 and the light receiving element 204 are arranged so that when the diaphragm 206 is flat, all of the reflected light 212 reaches the light receiving element 204. Alternatively, the light emitting element 202 and the light receiving element 204 may be arranged so that when the diaphragm 206 is in a position displaced downward from the flat position, all of the reflected light 212 reaches the light receiving element 204.

[0074] 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.

[0075] The chestpiece 110 according to the above-described embodiment can accurately detect the displacement of the biological surface 320. Specifically, in the above-described chestpiece 110, when a biological surface, which is an example of a measurement target, is in close contact with the diaphragm 206, a displacement signal is generated based on the displacement of the biological surface 320, which vibrates integrally with the diaphragm 206. Therefore, regardless of the frequency at which the biological surface 320 vibrates, the displacement of the biological surface 320 can be accurately detected. For example, the displacement of the biological surface 320 due to low-frequency vibrations of about 10 Hz can also be accurately detected. Such low-frequency vibrations are included in sounds (e.g., heart sounds) generated by vibrations propagated from inside the body due to heartbeats. In the chestpiece 110, the displacement signal does not change unless the diaphragm 206 is displaced. Therefore, ambient sounds and vibrations or accelerations due to movement of the chestpiece 110 are not detected as noise, resulting in output characteristics with a high S / N ratio.

[0076] [Hardware configuration of the electronic auscultation device in the first embodiment] Referring to FIG. 5, an example of the hardware configuration of the electronic auscultation device 100 will be described. The electronic auscultation device 100 includes the chestpiece 110 and a sound output unit 510. The sound output unit 510 is implemented by multiple circuit elements mounted on a circuit board included in the grip unit 120. The multiple circuit elements include a processor. The processor constituting the sound output unit 510 transmits a sound signal based on a displacement signal generated by the chestpiece 110 to an external sound output device. The sound signal transmitted by the sound output unit 510 represents the body sound of a living body (e.g., a human) having a body surface 320, and is therefore also referred to as a biosignal. The sound signal is transmitted to a sound output device 520 such as earphones or headphones. The sound signal is also transmitted to a computer 530 (e.g., a personal computer, smartphone, tablet, etc.) simultaneously with being transmitted to the sound output device 520. A user such as a doctor, nurse, or public health nurse can listen to the body sound represented by the digitally converted sound signal using the sound output device 520 or the computer 530. The sound output device 520 is a wired or wireless earphone or headphone.

[0077] The sound output unit 510 has the components shown in FIG. 5. Since the sound output unit 510 conforms to the earphones or headphones, it can transmit sound signals both wirelessly and via wired communication. The following describes the process by which the sound output device 520 outputs a sound signal via wired communication. The displacement signal output from the chestpiece 110 is filtered and amplified by the filter / amplifier 518 and supplied to the A / D converter 511 and the amplifier 515. For example, the filter / amplifier 518 attenuates low-frequency components of the displacement signal below a cutoff frequency (e.g., a value in the range of 5 Hz to 50 Hz (e.g., 10 Hz)) to extract heartbeat or breathing sounds. The filter / amplifier 518 filters the displacement signal at a different cutoff frequency for each operating mode of the electronic auscultation device 100. For example, when the electronic auscultation device 100 is in the heartbeat sound mode, the filter / amplifier 518 extracts the heartbeat sound from the displacement signal by setting the cutoff frequency to a value in the range of 10 Hz to less than 100 Hz (e.g., 10 Hz).When the electronic auscultation device 100 is in the breath sound mode, the filter / amplifier 518 extracts the breath sound from the displacement signal by setting the cutoff frequency to a value in the range of 50 Hz to less than 500 Hz (e.g., 100 Hz).

[0078] The amplifier 515 further amplifies the output from the filter / amplifier 518 and supplies the amplified sound signal to the wired communication unit 517. The wired communication unit 517 provides the amplified sound signal to the sound output device 520. The wired communication unit 517 is, for example, a 3.5 mm AUX terminal. The amplification gain of the amplifier 515 is adjusted by a volume adjustment unit 516. The sound output device 520 may be considered to constitute a part of the electronic auscultation device 100. In this case, the electronic auscultation device 100 has a chestpiece 110, a grip unit 120, and the sound output device 520.

[0079] Next, a process for the sound output device 520 to output a sound signal via wireless communication will be described. The A / D converter 511 digitizes the output from the filter / amplifier 518. The digital displacement signal is then amplified by the amplifier 512 and supplied to the encoder 513. The encoder 513 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 512 and the encoder 513 may be reversed. Then, a wireless communication unit 514 compliant with a wireless communication standard such as Bluetooth (registered trademark) provides the processed sound data to the sound output device 520. The amplification gain of the amplifier 512 is adjusted by the volume adjustment unit 516. Although an example has been described in which the electronic auscultation device 100 is capable of outputting a sound signal via both wireless and wired communication, the electronic auscultation device 100 may be capable of outputting a sound signal via only one of these communication methods.

[0080] The transmission of sound signals to the computer 530 is similar to the transmission of sound signals to the sound output device 520. The computer 530 can also visually display waveform data generated based on the sound signals. The waveform data may be generated by the computer 530 or by the electronic auscultation device 100. In addition, 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 520 or the computer 530).

[0081] The electronic auscultation device 100 can accurately detect displacement of the biological surface 320 regardless of the frequency at which the biological surface 320 vibrates. Therefore, the electronic auscultation device 100 enables good auscultation of both relatively low-frequency biological sounds, such as heartbeat sounds emitted by the body due to heartbeats, and relatively high-frequency biological sounds emitted by the body due to breathing. Respiratory sounds are biological vibrations that include a frequency band (first frequency band) that includes components in a frequency range from 500 Hz to 1 kHz, for example. Heartbeat sounds are biological vibrations that include a frequency band (second frequency band) that includes components in a frequency range from 30 Hz to 300 Hz, for example.

[0082] A mode switching button 123c is provided on the operation unit 123 of the electronic auscultation device 100. When the mode switching button 123c is pressed, the auscultation mode of the electronic auscultation device 100 switches between a mode suitable for auscultating heartbeat sounds (hereinafter referred to as the "heartbeat mode") and a mode suitable for auscultating breath sounds (hereinafter referred to as the "breath sound mode"). The electronic auscultation device 100 may have an auscultation mode other than the heartbeat sound mode and the breath sound mode. When auscultating heartbeat sounds, the user operates the mode switching button 123c provided on the operation unit 123 to select the heartbeat sound mode, which is one of the auscultation modes. 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, which is one of the auscultation modes.

[0083] The operation unit 123 is provided with 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 100 is provided with an LED as an indicator that displays whether the current auscultation mode is the heartbeat sound mode or the breath sound mode. 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. Note that the heartbeat sound mode and the breath sound mode are each an example of an auscultation mode.

[0084] [First Modification of the Electronic Auscultation Device in the First Embodiment] A first modified example of chestpiece 110 will be described with reference to FIGS. 6A and 6B. In FIGS. 6A and 6B, differences from FIGS. 3B, 3D, and 3E will be mainly described. In chestpiece 110 according to the first modified example, light-blocking member 302 is omitted, and opening 307 has a trapezoidal shape. The edges of opening 307 are formed by lower side 307a, upper side 307b, right side 307c, and left side 307d. Lower side 307a and upper side 307b are parallel to diaphragm 206 (e.g., its contact surface 206a) in a flat state, and lower side 307a is shorter than upper side 307b. Therefore, the width of opening 307 in a first plane parallel to diaphragm 206 is smaller than the width of opening 307 in a second plane parallel to diaphragm 206 and farther from diaphragm 206 than the first plane. Since the shape of the opening 307 is trapezoidal, the light irradiation area 301 is a trapezoidal area, as in the first embodiment.

[0085] Light passing through the opening 306 along the upper edge of the opening 306 is specularly reflected by the light reflecting portion 207 and then reaches the lower boundary line 301a of the light irradiation area 301 of the light receiving element 204 without being blocked by the light-shielding wall 305. Therefore, the upper edge of the opening 306 defines the lower boundary line 301a of the light irradiation area 301. On the other hand, light passing through the opening 306 along the lower edge of the opening 306 is specularly reflected by the light reflecting portion 207 and then blocked by the light-shielding wall 305, and does not reach the light receiving element 204. Therefore, the lower edge of the opening 306 does not define the light irradiation area 301. Therefore, the near incident light 211b is not narrowed by the diaphragm portion 209. Alternatively, the light passing through the opening 306 along the lower edge of the opening 306 may be specularly reflected by the light reflecting portion 207 and then reaches the light receiving element 204 without being blocked by the light-shielding wall 305. In this case, the lower side of opening 306 defines light irradiation area 301. In this configuration, the displacement signal remains constant as the displacement of diaphragm 206 ranges from zero to a predetermined value. Thereafter, when the lower side of opening 306 no longer defines light irradiation area 301, the displacement signal begins to decrease monotonically.

[0086] Light that passes through the opening 306, is specularly reflected by the light reflecting portion 207, and then passes through the opening 307 along the upper edge of the opening 307 reaches the upper boundary line 301b of the light irradiation area 301 of the light receiving element 204. Therefore, the upper edge of the opening 307 defines the upper boundary line 301b of the light irradiation area 301. In other words, the upper edge of the opening 307 is an example of an aperture section that narrows down the light specularly reflected by the light reflecting portion 207. On the other hand, light does not pass through the portion along the lower edge of the opening 307 because it is blocked by the light-shielding wall 304. Therefore, the lower edge of the opening 307 does not define the light irradiation area 301.

[0087] 3A , the lateral boundary line 301c and the lateral boundary line 301d of the light irradiation region 301 are defined by the right and left sides of the opening 307. Therefore, the ends of the lower boundary line 301a are defined by the right and left sides of the opening 307. Alternatively, the lateral boundary line 301c and the lateral boundary line 301d of the light irradiation region 301 may be defined by the right and left sides of the opening 306.

[0088] [Second Modification of the Electronic Auscultation Device in the First Embodiment] A second modified example of chestpiece 110 will be described with reference to Figures 6C to 6E. In Figures 6C to 6E, differences from Figures 3B, 3D, and 3E will be mainly described. Chestpiece 110 according to the second modified example does not include light-shielding wall 305. Therefore, chestpiece 110 does not have diaphragm portion 210.

[0089] In the second modified example, the light receiving surface of the light receiving element 204 is trapezoidal. The edges of the light receiving surface of the light receiving element 204 are composed of a lower side 204a, an upper side 204b, a right side 204c, and a left side 204d. The lower side 204a and the upper side 204b are each parallel to the diaphragm 206 (e.g., its contact surface 206a) in a flat state, and the lower side 204a is shorter than the upper side 204b. Therefore, the width of the light receiving surface of the light receiving element 204 in a first plane parallel to the diaphragm 206 is smaller than the width of the light receiving surface of the light receiving element 204 in a second plane parallel to the diaphragm 206 and farther from the diaphragm 206 than the first plane.

[0090] Light passing through the opening 306 along the upper edge of the opening 306 is specularly reflected by the light reflecting portion 207 and then reaches the lower boundary line 301a of the light irradiation area 301 of the light receiving element 204. Therefore, the upper edge of the opening 306 defines the lower boundary line 301a of the light irradiation area 301. On the other hand, as shown in FIG. 6C , light 610 passing through the opening 306 along the lower edge of the opening 306 is specularly reflected by the light reflecting portion 207 to become light 611 and reach the outside of the light receiving element 204. Therefore, the lower edge of the opening 306 does not define the light irradiation area 301. The same is true in FIG. 6D . The upper boundary line 301b of the light irradiation area 301 is defined by a line segment that forms the edge of the light-receiving area of ​​the light receiving element 204 (specifically, the upper edge of the light-receiving area of ​​the light receiving element 204). 6C and 6D, the lateral boundary lines 301c and 301d of the light irradiation area 301 are defined by line segments (specifically, the right and left sides of the light reception area of ​​the light receiving element 204) that form the edges of the light reception area of ​​the light receiving element 204. In other words, the lateral boundary lines 301c and 301d of the light irradiation area 301 may alternatively be defined by the right and left sides of the opening 306.

[0091] Referring to FIG. 6E, a change in the light irradiation area 301 formed by the reflected light 212 that reaches the light receiving surface of the light receiving element 204 will be described. FIG. 6E shows a plan view of the light receiving surface of the light receiving element 204. The left side of FIG. 6E shows the position of the light irradiation area 301 when the diaphragm 206 is in a flat state. The center of FIG. 6E shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 from the flat state due to pressure from the biological surface 320. The right side of FIG. 6E shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2, which is larger than the displacement amount d1, due to pressure from the biological surface 320.

[0092] 6E, the effective area 300 is a trapezoidal region. Specifically, the edges of the effective area 300 are formed by a lower boundary line 301a, an upper boundary line 301b, a side boundary line 301c, and a side boundary line 301d. The lower boundary line 301a and the upper boundary line 301b are each parallel to the diaphragm 206 (e.g., its contact surface 206a) in a flat state, and the lower boundary line 301a is shorter than the upper boundary line 301b. The end of the lower boundary line 301a is defined by the edge of the light-receiving surface of the light-receiving element 204.

[0093] As shown in FIG. 6E, the length of the lower boundary line 301a changes when the contact surface 206a is displaced. Specifically, the length of the lower boundary line 301a when the diaphragm 206 is flat (left side of FIG. 6E) is defined as L0. The length of the lower boundary line 301a when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 (center of FIG. 6E) is defined as L1. The length of the lower boundary line 301a when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2 that is larger than the displacement amount d1 (right side of FIG. 6E) is defined as L2. In this case, L0 <L1<L2 Therefore, the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2.

[0094] [Third Modification of the Electronic Auscultation Device in the First Embodiment] A third modified example of chestpiece 110 will be described with reference to Figures 6F to 6I. In Figures 6F to 6I, differences from Figures 3B, 3D, 3E, and 4(a) will be mainly described.

[0095] Light passing through opening 306 along the lower edge of opening 306 is specularly reflected by light reflecting portion 207 and then reaches light irradiation region 301 of light receiving element 204 without being blocked by light-shielding wall 305 or light-shielding member 302. Therefore, the lower edge of opening 306 defines upper boundary line 301b of light irradiation region 301. On the other hand, as shown in FIG. 6F, light 620 passing through opening 306 along the upper edge of opening 306 is specularly reflected by light reflecting portion 207 to become light 621, and then is blocked by light-shielding wall 305 or light-shielding member 302 and does not reach light receiving element 204. Therefore, the upper edge of opening 306 does not define light irradiation region 301. The same is true in FIG. 6G.

[0096] Light that passes through opening 306, is specularly reflected by light reflecting portion 207, passes through opening 307, and then passes through opening 302a along the lower edge of opening 302a reaches lower boundary line 301a of light irradiation area 301 of light receiving element 204. Therefore, the lower edge of opening 302a defines lower boundary line 301a of light irradiation area 301. On the other hand, light does not pass through the portion along the lower edge of opening 307 because it is blocked by light-shielding wall 304. Therefore, the upper edge of opening 307 does not define light irradiation area 301.

[0097] 6F and 6G, when the diaphragm 206 is pressed by the biological surface 320, the positions of the effective range 300, the far boundary 300a, the near boundary 300b, the light irradiation area 301, the lower boundary 301a, and the upper boundary 301b all change. As described above, the upper boundary 301b is defined by the lower side of the opening 306 of the diaphragm section 209 on the light-emitting element 202 side. The upper boundary 301b moves in response to the displacement of the contact surface 206a. On the other hand, the lower boundary 301a and the lateral boundary lines 301c and 301d do not substantially move in response to the displacement of the contact surface 206a.

[0098] Referring to FIG. 6H, a change in the light irradiation area 301 formed by the reflected light 212 that reaches the light receiving surface of the light receiving element 204 will be described. FIG. 6H shows a plan view of the light receiving surface of the light receiving element 204. The left side of FIG. 6H shows the position of the light irradiation area 301 when the diaphragm 206 is in a flat state. The center of FIG. 6H shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 from the flat state due to pressure from the biological surface 320. The right side of FIG. 6H shows the position of the light irradiation area 301 when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2, which is larger than the displacement amount d1, due to pressure from the biological surface 320.

[0099] 6H, the effective range 300 is a trapezoidal region. Specifically, the edges of the effective range 300 are formed by a lower boundary line 301a, an upper boundary line 301b, a side boundary line 301c, and a side boundary line 301d. The lower boundary line 301a and the upper boundary line 301b are each parallel to the diaphragm 206 (e.g., its contact surface 206a) in the flat state, and the lower boundary line 301a is shorter than the upper boundary line 301b.

[0100] The area of ​​the light-irradiated region 301 is determined by the lower boundary line 301a, the upper boundary line 301b, and the side boundary lines 301c and 301d. As shown in FIG. 6H, the upper boundary line 301b of the light-irradiated region 301 changes in the x′-axis direction in response to the displacement of the contact surface 206a. On the other hand, the lower boundary line 301a and the side boundary lines 301c and 301d do not substantially move in response to the displacement of the contact surface 206a. Therefore, the area of ​​the light-irradiated region 301 changes in response to the movement of the upper boundary line 301b. The length of the lower boundary line 301a does not change even when the contact surface 206a is displaced. On the other hand, the lengths of the side boundary lines 301c and 301d change when the contact surface 206a is displaced.

[0101] As the area of ​​the light-irradiated region 301 changes, the signal output from the light-receiving element 204 also changes. Specifically, the greater the displacement of the contact surface 206a of the diaphragm 206 from the flat state, the longer the distance between the lower boundary line 301a and the upper boundary line 301b (i.e., the lengths of the lateral boundary lines 301c and 301d), and the greater the area of ​​the light-irradiated region 301. Therefore, the greater the displacement of the diaphragm 206 from the flat state, the greater the amount of light received by the light-receiving element 204. Accordingly, the signal output from the light-receiving element 204 also increases. As shown in FIG. 6H, the amount of movement of the upper boundary line 301b accompanying the movement of the light-reflecting portion 207 is greater than the amount of movement of the lower boundary line 301a accompanying the movement of the light-reflecting portion 207.

[0102] The length of the upper boundary line 301b changes when the contact surface 206a is displaced. Specifically, the length of the upper boundary line 301b when the diaphragm 206 is flat (left side of FIG. 6H) is defined as L0. The length of the upper boundary line 301b when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d1 (center of FIG. 6H) is defined as L1. The length of the upper boundary line 301b when the contact surface 206a of the diaphragm 206 is displaced by a displacement amount d2 that is larger than the displacement amount d1 (right side of FIG. 6H) is defined as L2. In this case, L0 <L1<L2 Therefore, the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2.

[0103] [Relationship between the displacement amount of the living body surface and the displacement signal of the electronic auscultation device according to the third modification] The relationship between the displacement amount of the biological surface 320 and the displacement signal will be described with reference to Fig. 6I. The displacement signal represents the voltage output from the optical receiver circuit board 205. A graph 600 in Fig. 6I represents the relationship between the displacement amount of the biological surface 320 and the displacement signal. The horizontal axis of the graph 600 represents the displacement amount of the biological surface 320, and represents the displacement signal generated by the optical receiver circuit board 205.

[0104] When the displacement of the biological surface 320 is zero, the displacement signal has a value corresponding to the area of ​​the light-irradiated region 301 shown in FIG. 6F. As the displacement of the contact surface 206a increases, the upper end reflected light 212b moves away from the diaphragm 206, and the area of ​​the light-irradiated region 301 increases monotonically and linearly. That is, the amount of light emitted by the light-emitting element that reaches the light-receiving element 204 increases monotonically and linearly. As a result, the displacement signal output from the light-receiving element 204 also increases monotonically and linearly. Thereafter, when the upper end reflected light 212b reaches the light-shielding wall 305, the displacement signal becomes constant.

[0105] The relationship between the displacement amount of the biological surface 320 and the displacement signal will be described with reference to Fig. 6I. A graph 600 in Fig. 6I shows the relationship between the displacement amount of the biological surface 320 and the displacement signal. The horizontal axis of the graph 600 represents the displacement amount of the biological surface 320, and represents the displacement signal generated by the light receiving circuit board 205.

[0106] 6I, as the displacement of the reflected light 212 increases, the portion of the reflected light 212 that reaches the light receiving element 204 increases monotonically and nonlinearly. In the graph 600, Vmin is the value of the displacement signal when the displacement d is zero. Vmin is determined by the amount of light emitted by the light emitting element 202 and the sensitivity of the light receiving element 204. In the graph 600, Vmax represents the upper limit of the displacement signal.

[0107] As described above, the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the area of ​​light irradiation region 301 per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2. Therefore, the amount of change in the displacement signal per unit displacement of contact surface 206a when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d1 is smaller than the amount of change in the displacement signal per unit displacement of contact surface 206a of diaphragm 206 when the amount of displacement of contact surface 206a of diaphragm 206 is displacement amount d2.

[0108] Specifically, the amount of change in the displacement signal caused by the contact surface 206a of the diaphragm 206 being further displaced by w1 from the state where the amount of displacement is d1 is defined as w5. Also, the amount of change in the displacement signal caused by the contact surface 206a of the diaphragm 206 being further displaced by w1 from the state where the amount of displacement is d2 is defined as w6. In this case, w5 <w6 That is, the greater the displacement of the contact surface 206a of the diaphragm 206, the higher the light receiving sensitivity of the light receiving element 204.

[0109] [Fourth Modification of the Electronic Auscultation Device in the First Embodiment] In chestpiece 110 according to the fourth modification, light blocking member 302 is omitted from the third modification, and opening 307 has a trapezoidal shape similar to that of the first modification. Therefore, similar to the first modification, light irradiation area 301 in the fourth modification is also a trapezoidal area.

[0110] [Fifth Modification of the Electronic Auscultation Device in the First Embodiment] In chestpiece 110 according to the fifth modification, light-shielding member 302 is omitted from the third modification, and light-receiving element 204 has a trapezoidal shape, similar to that of the second modification. Therefore, similar to the second modification, light irradiation area 301 in the fifth modification is also a trapezoidal area.

[0111] <Modifications of the above embodiment> In the above-described embodiment and each modified example, the lateral boundary lines 301c and 301d of the light irradiation area 301 are both straight lines. Alternatively, the lateral boundary lines 301c and 301d of the light irradiation area 301 may be curved lines, broken lines, or a combination thereof. For example, the opening 307 of the diaphragm section 210 may be formed so that the light irradiation area 301 has the shape shown in FIG. 7 when the diaphragm 206 is in a flat state.

[0112] 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 light reflecting portion 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 separate light-emitting element 202 and reflected by light reflecting portion 207. The displacement of diaphragm 206 may be detected based on the total amount of light received by the multiple light-receiving elements 204.

[0113] The electronic auscultation device described above is primarily intended as a diagnostic tool in which doctors, nurses, and public health nurses place a diaphragm on the surface of a patient's body to listen to heartbeat and breathing sounds. However, it is also conceivable that the electronic auscultation device could be used by general users other than medical professionals, rather than as a diagnostic tool. For example, it is conceivable that general users would use the electronic auscultation device for the purpose of promoting and managing their health. In such cases, the electronic auscultation device could be installed in a health management device that has the function of measuring vital data such as pulse rate and body temperature. Therefore, the electronic auscultation device of this embodiment can also be applied to a health management device that can simultaneously acquire biological information other than biological sounds.

[0114] Furthermore, the electronic auscultation device of this embodiment may be used for diagnosing animals other than humans, i.e., it goes without saying that it can be used as an electronic auscultation device for pets used by veterinarians.

[0115] The electronic auscultation device of this embodiment is sometimes referred to as a "displacement detection device" because it detects the displacement of a diaphragm. Aside from auscultation, the displacement detection device can also be used to detect abnormal industrial sounds. For example, when an abnormality occurs in a gas or water pipeline, low-frequency sounds that are difficult for the human ear to hear can be generated. The displacement detection device of this embodiment can be used as a device for identifying the source of such low-frequency sounds and listening for them. When using the displacement detection device for such purposes, a user contacts the diaphragm of the displacement detection device with a target object. The displacement detection device then detects the vibration of the target object, converts the displacement signal representing the vibration into a sound signal, and transmits it to a sound output device. This allows the user to identify the source of the low-frequency sound. Potential targets that are sources of low-frequency sounds include gas or water pipelines, as well as outdoor units of air conditioners. Motors, which are sources of vibration, can also be target objects. Various industrial machines can also be target objects. In other words, in addition to auscultation, the displacement detection device can be used for various purposes as a device that detects the vibration of a target object and outputs sound.

[0116] <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.

[0117] <Summary of the embodiment> (Item 1) a diaphragm that contacts an object to be measured, the diaphragm having a light reflecting portion provided on a surface opposite to a contact surface that contacts the object to be measured; A light emitting diode; a diaphragm for diaphragming light emitted from the light-emitting diode; a light receiving element having a light receiving surface that receives light that passes through the diaphragm portion and is specularly reflected by the light reflecting portion; an output means for outputting a signal corresponding to the light in a light-irradiated area formed by the specularly reflected light that has reached the light-receiving surface; Equipped with the diaphragm is configured to be elastically deformed by pressure from an object to be measured that is in contact with the contact surface, a boundary line between the light-irradiated region and a region other than the light-irradiated region on the light-receiving surface, which is formed by light narrowed by the diaphragm and specularly reflected by the light-reflecting portion, moves in accordance with the displacement of the contact surface due to elastic deformation of the diaphragm, thereby changing the area of ​​the light-irradiated region on the light-receiving surface and changing the output of the output means; The length of the boundary line when the contact surface is displaced by a first displacement amount due to pressure from the object to be measured is defined as L1, When the length of the boundary line when the contact surface is pressed by the object to be measured and displaced by a second displacement amount that is larger than the first displacement amount is defined as L2, L1 <L2 An electronic auscultation device characterized by satisfying the relationship: (Item 2) 2. The electronic auscultation device according to item 1, further comprising a light-shielding member having an opening formed between the light reflecting portion and the light receiving element. (Item 3) 3. The electronic auscultation device according to item 2, wherein the end of the boundary line is defined by the edge of the opening of the light-blocking member. (Item 4) 4. The electronic auscultation device according to item 2 or 3, wherein the width of the opening of the light-blocking member in a first plane parallel to the diaphragm is smaller than the width of the opening of the light-blocking member in a second plane parallel to the diaphragm and farther from the diaphragm than the first plane. (Item 5) 5. The electronic auscultation device according to any one of items 2 to 4, wherein the light-blocking member is in contact with the light-receiving element. (Item 6) 2. The electronic auscultation device according to item 1, wherein the end of the boundary line is defined by the edge of the light receiving surface. (Item 7) 7. The electronic auscultation device according to item 1 or 6, wherein the width of the light receiving surface in a first plane parallel to the diaphragm is smaller than the width of the light receiving surface in a second plane parallel to the diaphragm and farther from the diaphragm than the first plane. (Item 8) The electronic auscultation device according to any one of items 1 to 7, further comprising an extraction means for extracting heartbeat sounds or breathing sounds from the signal output from the light receiving element. (Item 9) a diaphragm that contacts an object to be measured, the diaphragm having a light reflecting portion provided on a surface opposite to a contact surface that contacts the object to be measured; A light emitting diode; a diaphragm for diaphragming light emitted from the light-emitting diode; a light receiving element having a light receiving surface that receives light that passes through the diaphragm portion and is specularly reflected by the light reflecting portion; an output means for outputting a signal corresponding to the light in a light-irradiated area formed by the specularly reflected light that has reached the light-receiving surface; Equipped with the diaphragm is configured to be elastically deformed by pressure from an object to be measured that is in contact with the contact surface, a boundary line between the light-irradiated region and a region other than the light-irradiated region on the light-receiving surface, which is formed by light narrowed by the diaphragm and specularly reflected by the light-reflecting portion, moves in accordance with the displacement of the contact surface due to elastic deformation of the diaphragm, thereby changing the area of ​​the light-irradiated region on the light-receiving surface and changing the output of the output means; An electronic auscultation device characterized in that the amount of change in the area of ​​the light-irradiated region per unit displacement of the contact surface when the displacement of the contact surface is a first displacement amount is smaller than the amount of change in the area of ​​the light-irradiated region per unit displacement of the contact surface when the displacement of the contact surface is a second displacement amount that is larger than the first displacement amount.

[0118] 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]

[0119] 100 Electronic stethoscope device, 110 Chest piece, 120 Grip, 202 Light-emitting element, 204 Light-receiving element, 206 Diaphragm

Claims

1. a diaphragm that contacts an object to be measured, the diaphragm having a light reflecting portion provided on a surface opposite to a contact surface that contacts the object to be measured; A light emitting diode, a diaphragm for diaphragming light emitted from the light-emitting diode; a light receiving element having a light receiving surface that receives light that passes through the diaphragm portion and is specularly reflected by the light reflecting portion; an output means for outputting a signal corresponding to the light in a light-irradiated area formed by the specularly reflected light that has reached the light-receiving surface; Equipped with the diaphragm is configured to be elastically deformed by pressure from an object to be measured that is in contact with the contact surface, a boundary line between the light-irradiated region and a region other than the light-irradiated region on the light-receiving surface, which is formed by light narrowed by the diaphragm and specularly reflected by the light-reflecting portion, moves in accordance with the displacement of the contact surface due to elastic deformation of the diaphragm, thereby changing the area of ​​the light-irradiated region on the light-receiving surface and changing the output of the output means; a length of the boundary line when the contact surface is displaced by a first displacement amount due to pressure from the object to be measured is defined as L1; When the length of the boundary line when the contact surface is pressed by the object to be measured and displaced by a second displacement amount that is larger than the first displacement amount is defined as L2, L1<L2 An electronic auscultation device characterized by satisfying the relationship:

2. 2. The electronic auscultation device according to claim 1, further comprising a light-shielding member having an opening formed therein between the light reflecting portion and the light receiving element.

3. 3. The electronic auscultation device according to claim 2, wherein the ends of the boundary line are defined by edges of the opening in the light-blocking member.

4. 3. The electronic auscultation device according to claim 2, wherein the width of the opening of the light-blocking member in a first plane parallel to the diaphragm is smaller than the width of the opening of the light-blocking member in a second plane parallel to the diaphragm and farther from the diaphragm than the first plane.

5. 3. The electronic auscultation device according to claim 2, wherein the light-blocking member is in contact with the light-receiving element.

6. 2. The electronic auscultation device according to claim 1, wherein the ends of the boundary line are defined by edges of the light receiving surface.

7. 2. The electronic auscultation device according to claim 1, wherein the width of the light receiving surface in a first plane parallel to the diaphragm is smaller than the width of the light receiving surface in a second plane parallel to the diaphragm and farther from the diaphragm than the first plane.

8. 2. The electronic auscultation device according to claim 1, further comprising an extracting means for extracting heartbeat sounds or breathing sounds from the signal output from the light receiving element.

9. a diaphragm that contacts an object to be measured, the diaphragm having a light reflecting portion provided on a surface opposite to a contact surface that contacts the object to be measured; A light emitting diode, a diaphragm for diaphragming light emitted from the light-emitting diode; a light receiving element having a light receiving surface that receives light that passes through the diaphragm portion and is specularly reflected by the light reflecting portion; an output means for outputting a signal corresponding to the light in a light-irradiated area formed by the specularly reflected light that has reached the light-receiving surface; Equipped with the diaphragm is configured to be elastically deformed by pressure from an object to be measured that is in contact with the contact surface, a boundary line between the light-irradiated region and a region other than the light-irradiated region on the light-receiving surface, which is formed by light narrowed by the diaphragm and specularly reflected by the light-reflecting portion, moves in accordance with the displacement of the contact surface due to elastic deformation of the diaphragm, thereby changing the area of ​​the light-irradiated region on the light-receiving surface and changing the output of the output means; An electronic auscultation device characterized in that the amount of change in the area of ​​the light-irradiated region per unit displacement of the contact surface when the displacement of the contact surface is a first displacement amount is smaller than the amount of change in the area of ​​the light-irradiated region per unit displacement of the contact surface when the displacement of the contact surface is a second displacement amount that is larger than the first displacement amount.

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