Detection device and electronic auscultation device

Abstract

To provide an electronic stethoscope that suppresses the influence of optical properties. [Solution] A detection device for detecting vibrations of a target to be detected, comprising: a diaphragm having a reflective surface that moves in accordance with the vibrations of the target to be detected; a light-emitting unit that emits light toward the reflective surface; a light-receiving unit that receives the light reflected by the reflective surface and outputs a signal corresponding to the light; an aperture unit that narrows the light emitted by the light-emitting unit before it reaches the light-receiving unit; a calibration execution means that performs at least one of the following as calibration: correction of the light intensity of the light-emitting unit and correction of the light-receiving sensitivity of the light-receiving unit; and a determination means that determines whether or not calibration can be performed according to the vibration state or pressing state of the diaphragm.

Description

Technical Field

[0001] The present invention relates to a detection device and an electronic stethoscope including the detection device.

Background Art

[0002] In recent years, electronic stethoscopes having sensors for measuring body vibrations and capable of acquiring body sounds by the sensors have begun to spread. Patent Document 1 discloses a device for measuring body signals using an optical element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An electronic stethoscope using an optical element needs to precisely arrange a light-emitting element, a light-receiving element, and further a diaphragm film in order to detect minute vibrations of a living body. However, assembly tolerances in the manufacture of parts related to optical characteristics, component characteristic tolerances of the light-emitting element and the light-receiving element, and further changes in the amount of light due to the durability of the light-emitting element have a great influence on the optical characteristics.

[0005] The present invention provides an electronic stethoscope that suppresses the influence of optical characteristics.

Means for Solving the Problems

[0006] The detection device of the present invention is a detection device that detects vibrations of a detection target, a diaphragm having a reflecting surface that moves in response to the vibrations of the detection target, a light-emitting unit that emits light toward the reflecting surface, a light-receiving unit that receives the light reflected by the reflecting surface and outputs a signal corresponding to the light, A diaphragm unit that narrows the light emitted by the light-emitting unit before it reaches the light-receiving unit, Calibration execution means for performing at least one of the following as calibration: correction of the light intensity of the light-emitting part and correction of the light-receiving sensitivity of the light-receiving part. A determination means for determining whether or not the calibration can be performed according to the vibration state or pressing state of the diaphragm, It is characterized by being equipped with [the following features].

[0007] According to the present invention, an electronic stethoscope can be provided that suppresses the influence of optical properties. [Brief explanation of the drawing]

[0008] [Figure 1A] This is a schematic diagram illustrating an example of the external appearance of the electronic stethoscope according to the first embodiment. [Figure 1B] This is a schematic diagram illustrating an example of the external appearance of the electronic stethoscope according to the first embodiment. [Figure 2] This is a schematic diagram illustrating an example of the configuration of the chestpiece according to the first embodiment. [Figure 3A] This is a schematic diagram illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3B] This is a schematic diagram illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3C] This is a schematic diagram illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3D] This is a schematic diagram illustrating an example of the operation of the chestpiece of the first embodiment. [Figure 3E] This is a schematic diagram illustrating an example of the change in the light-receiving range of the first embodiment. [Figure 4] This figure illustrates the relationship between the amount of displacement and the displacement signal in the first embodiment. [Figure 5] This figure illustrates an example of the hardware configuration of the electronic stethoscope according to the first embodiment. [Figure 6A] This diagram illustrates the variation in displacement signals. [Figure 6B] This diagram illustrates the variation in displacement signals. [Figure 7] It is a diagram for explaining an example of the overall circuit configuration of an electronic stethoscope. [Figure 8A] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 8B] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 8C] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 8D] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 8E] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 8F] It is a diagram for explaining an example of the circuit configuration of an electronic stethoscope. [Figure 9] It is a diagram for explaining an example of the waveform of a displacement signal. [Figure 10] It is a diagram for explaining the calibration processing flow of the first embodiment. [Figure 11A] It is a diagram for explaining an example of a light quantity correction method. [Figure 11B] It is a diagram for explaining an example of a light quantity correction method. [Figure 11C] It is a diagram for explaining an example of a light quantity correction method. [Figure 11D] It is a diagram for explaining an example of a light quantity correction method. [Figure 11E] It is a diagram for explaining an example of a light quantity correction method. [Figure 12] It is a diagram for explaining the calibration processing flow of the second embodiment. [Figure 13] It is a diagram for explaining an example of the hardware configuration of the electronic stethoscope of the third embodiment. [Figure 14] It is a diagram for explaining the calibration processing flow of the third embodiment. [Figure 15] It is a diagram for explaining an example of the hardware configuration of the electronic stethoscope of the fourth embodiment. [Figure 16] It is a diagram for explaining the calibration processing flow of the fourth embodiment. [Figure 17]This figure illustrates an example of the hardware configuration of the electronic stethoscope according to the fifth embodiment. [Figure 18] This diagram illustrates the calibration process flow of the fifth embodiment. [Modes for carrying out the invention]

[0009] The embodiments for carrying out this invention will be described in detail below with reference to the drawings, based on examples. The dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration and various conditions of the device to which the invention is applied. In other words, the scope of this invention is not intended to be limited to the following embodiments.

[0010] <First Embodiment> [Appearance of the electronic stethoscope in the first embodiment] The appearance of the electronic stethoscope 100 according to the first embodiment will be described with reference to Figures 1A and 1B. Note that the following drawings may include a coordinate system CS, a three-dimensional Cartesian coordinate system having x, y, and z axes, to indicate direction. In these descriptions, the positive z-axis direction may be referred to as the upper side, and the negative z-axis direction as the lower side. Figure 1A shows the appearance of the electronic stethoscope 100 viewed from one direction, and Figure 1B shows the appearance of the electronic stethoscope 100 viewed from another direction. The electronic stethoscope 100 is a diagnostic instrument for listening to internal sounds of living organisms such as humans or animals. The electronic stethoscope 100 is mainly used to listen to heart sounds and respiratory sounds.

[0011] As shown in Figure 1A, the electronic auscultation device 100 has a chestpiece 110 and a gripping part 120. The chestpiece 110 is a unit that, when used for diagnosis with the electronic auscultation device 100, is brought into contact with the surface of a living body, which is an example of a detection target (object to be measured, subject), to detect (measure) minute vibrations (displacements) of the living body's surface and capture living sounds. The chestpiece 110 functions as a detection device that detects minute displacements and vibrations of the living body's surface in close contact with it via a diaphragm 206, which will be described later.

[0012] The gripping part 120 is used by the user of the electronic stethoscope 100 (for example, a doctor, nurse, or public health nurse). The gripping part 120 is held when the ear phragm 206 is brought into close contact with the biological surface. Hereafter, the user of the electronic stethoscope 100 will be simply referred to as the user. The gripping part 120 is rod-shaped as shown in Figures 1A and 1B, and the chestpiece 110 is attached to one end (the negative x-axis direction in Figures 1A and 1B).

[0013] The gripping unit 120 has a housing 121. The gripping unit 120 houses a battery and a circuit board inside the housing 121. The battery stores the operating power of the electronic stethoscope 100. The circuit board has circuit elements for controlling the operation of the electronic stethoscope 100. The gripping unit 120 has a display unit 122, an operating unit 123, a power switch 124, and a connector 125 on the outer surface of the housing 121.

[0014] The display unit 122 displays the status of the electronic stethoscope 100. The display unit 122 may include multiple indicators. In this embodiment, as shown in Figure 1A, the display unit 122 includes four indicators. In this embodiment, the multiple indicators include an indicator that shows whether the electronic stethoscope 100 is powered on or off. The multiple indicators also include an indicator that shows the current operating mode of the electronic stethoscope 100. The multiple indicators also include an indicator that shows whether the electronic stethoscope 100 is wirelessly connected to an external device. The multiple indicators also include an indicator that shows whether the chestpiece 110 is pressed against a biological surface.

[0015] As shown in Figure 1A, the display unit 122 is positioned near the chestpiece 110 on one end of the outer surface of the housing 121, on the side opposite to the surface to which the chestpiece 110 is connected, in the x-axis direction. In this embodiment, "near the chestpiece 110" means closer to the chestpiece 110 than the center of the gripping portion 120. Note that the display unit 122 does not need to include all of the indicators described above, and the status of the electronic stethoscope 100 may be displayed by a liquid crystal panel or an electrostatic panel instead of or in addition to the multiple indicators.

[0016] The control unit 123 receives input from the user. The control unit 123 may include a number of physical buttons for receiving settings for the electronic stethoscope 100. In this embodiment, the control unit 123 includes four buttons as shown in Figure 1A. Specifically, the control unit 123 includes a volume up button 123a and a volume down button 123b as volume adjustment buttons for adjusting the volume of the output sound. When a volume adjustment button is pressed, the electronic stethoscope 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.

[0017] The control unit 123 also includes a mode switching button 123c for switching the operating mode of the electronic stethoscope 100. Pressing the mode switching button 123c switches the operating mode, as described later. In other words, the mode switching button 123c receives instructions from the user regarding the mode transition of the electronic stethoscope 100. Based on the instructions from the user using the mode switching button 123c, the electronic stethoscope 100 selects one of several operating modes and operates in that operating mode.

[0018] The operating unit 123 also includes a calibration button 123d for performing calibration of the electronic stethoscope 100. When the calibration button 123d is pressed, calibration is performed to maintain the accuracy of the output of the electronic stethoscope 100. In this embodiment, the calibration button 123d is positioned alongside the mode switching button 123c in the x-axis direction, and is closer to the center of the gripping unit 120 than the mode switching button 123c. The calibration button 123d may be located away from the mode switching button 123c and the volume adjustment button. For example, calibration The control button 123d may be positioned next to the power switch 124.

[0019] The control unit 123 may include a touch panel instead of multiple physical buttons. The display unit 122 and the control unit 123 may be integrated as a touchscreen. The electronic stethoscope 100 may automatically select an operating mode in response to a signal representing vibrations of the acquired biological surface, instead of, or in addition to, instructions from the user using the mode switching button 123c.

[0020] The control unit 123, like the display unit 122, is located on the outer surface of the housing 121, on the side opposite to the chestpiece 110, near the chestpiece 110, at one end in the x-axis direction. This arrangement allows the user to operate the control unit 123 (for example, with their thumb) while holding the gripping unit 120 during use of the electronic stethoscope 100. The display unit 122 is positioned further away from the center of the gripping unit 120 in the x-axis direction than the control unit 123. This arrangement allows the user to maintain visibility of the display unit 122 even when operating the control unit 123 during use of the electronic stethoscope 100.

[0021] The power switch 124 is a switch that turns the power of the electronic stethoscope 100 on and off. The connector 125 is a connector for receiving a cable or connector of an external device. Power is supplied from the external device to the battery included in the gripping part 120 through the connector 125. The power switch 124 may be provided on the chestpiece 110 instead of on the gripping part 120. Also, if the display unit 122 and the operation unit 123 are configured as a single touchscreen, the power switch 124 may also be included in the touchscreen. The connector 125 may be provided on the chestpiece 110 instead of on the gripping part 120. Furthermore, the electronic stethoscope 100 does not have to include the connector 125. In this case, the electronic stethoscope 100 may have a wireless charging function or may be configured to have a replaceable battery.

[0022] [Chestpiece configuration of the electronic stethoscope in the first embodiment] Referring to Figure 2, an example of the configuration of the chestpiece 110 will be described. The upper part of Figure 2 shows a cross-sectional view of the chestpiece 110, and the lower part of Figure 2 shows a plan view of the chestpiece 110. In the plan view, only the light-emitting circuit board 203, light-receiving circuit board 205, diaphragm 206, and light-reflecting part 207 are shown to clarify the positional relationship of the components.

[0023] 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 part 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 part 207. The holding member 201 has an aperture portion 209 and an aperture portion 210 formed thereon. Therefore, the housing 208 also houses the aperture portion 209 and the aperture portion 210. The diaphragm 206, together with the housing 208, forms part of the exterior of the electronic stethoscope 100.

[0024] The light-emitting element 202 is a light source that emits light. The power supplied to the light-emitting element 202 is supplied from an external power source (the battery of the gripping part 120) of the chestpiece 110. In this embodiment, the light-emitting element 202 uses a light-emitting diode (LED).

[0025] The light-emitting element 202 is mounted on the light-emitting circuit board 203. The light-emitting circuit board 203 includes, for example, peripheral circuits for controlling the amount of light emitted by the light-emitting element 202, and power terminals for receiving power from an external power source of the chestpiece 110. The light-emitting circuit board 203 may be a printed circuit board such as a flexible circuit board, or it may be a paper phenolic substrate or a glass epoxy substrate. Light-emitting circuit board 203 including the light-emitting element 202 It functions as a light-emitting part.

[0026] The light-receiving element 204 functions as a photosensor that generates an electrical signal based on the amount of light it receives, using power supplied from an external power source (the battery of the gripping section 120) to the chestpiece 110. The power supplied to the light-receiving element 204 is supplied from an external power source (for example, the battery of the gripping section 120) to the chestpiece 110. The light-receiving element 204 may be, for example, a phototransistor or a complementary metal-oxide-semiconductor (CMOS) sensor.

[0027] The light-receiving element 204 is mounted on the 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 signals from the light-receiving element 204, signal terminals for outputting signals to external devices of the chestpiece 110, and power terminals for receiving power from an external power supply of the chestpiece 110. The light-receiving circuit board 205, including the light-receiving element 204, functions as a light-receiving unit.

[0028] 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.

[0029] The diaphragm 206 has a contact surface 206a that contacts a biological surface, which is an example of a target to be detected, and an inner surface 206b that is the opposite side of the contact surface 206a. The diaphragm 206 is configured to elastically deform when pressed by the target to be detected that comes into contact with the contact surface 206a. The contact surface 206a is the surface facing outward from the chestpiece 110, and the inner surface 206b is the surface facing inward from the chestpiece 110. The inner surface 206b of the diaphragm 206 is provided with a light-reflecting portion 207, which will be described later.

[0030] In this embodiment, the diaphragm 206 uses a laminate of glass epoxy resin, which is made by impregnating glass fibers with epoxy resin and then heat-curing it. Its thickness is 230 μm. The diaphragm 206 also has a ring-shaped rim integrated into it for fixing the diaphragm 206 to the retaining member 201 or the housing 208. In this embodiment, the contact surface 206a and inner surface 206b of the diaphragm 206 refer to the portion of the diaphragm that does not include the ring-shaped rim integrated into 206.

[0031] The diaphragm 206 is held by the retaining member 201. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 is positioned to contact a biological surface, which is an example of a target for detection. The diaphragm 206 constitutes part of the exterior of the chestpiece 110. The diaphragm 206 is positioned such that its contact surface 206a contacts a biological surface when the electronic stethoscope 100 is in use, and its inner surface 206b faces the retaining member 201.

[0032] The diaphragm 206 has a fixed portion 206c that is fixed to the holding member 201. The fixed portion 206c is located on the outer circumference of the diaphragm 206. The inner circumference of the diaphragm 206 (i.e., the portion inside the fixed portion 206c) is not fixed to the holding member 201. Therefore, the diaphragm 206 can vibrate in the z-axis direction with the fixed portion 206c as a node. Specifically, when the chestpiece 110 is used, the diaphragm 206 vibrates with the fixed portion 206c as a node in response to the displacement of the biological surface. In this vibration, the center 206e of the diaphragm 206 becomes an antinode. The diaphragm 206 functions as a vibrating part that vibrates together with the object to be detected.

[0033] The light-reflecting part 207 reflects light emitted from the light-emitting element 202. The light-reflecting part 207 is bonded to the inner surface 206b of the diaphragm 206 and moves integrally with the diaphragm 206 in the z-axis direction in conjunction with the vibration of the diaphragm 206, which is in close contact with the biological surface. 207 has a circular outer edge in the plan view. The light reflecting portion 207 may have a diameter of 15 mm to 20 mm. The light reflecting portion 207 is positioned to cover the region 206d that includes the center 206e of the diaphragm 206. Since the displacement of the diaphragm 206 changes most significantly at the center 206e, the displacement of the diaphragm 206 can be detected with high sensitivity by reflecting light from the light-emitting element 202 in the region including the center 206e. In this embodiment, the light reflecting portion 207 is positioned to cover the center 206e, but it may also be positioned to cover the region of the diaphragm 206 that does not include the center 206e.

[0034] The light-reflecting portion 207 is made of, for example, an aluminum vapor-deposited film. The light-reflecting portion 207 is a sheet-like member attached to the inner surface 206b (the surface opposite to the contact surface 206a) of the diaphragm 206. That is, the inner surface 206b functions as a reflective surface that reflects light emitted from the light-emitting element 202 toward the inner surface 206b. More specifically, the upper surface of the light-reflecting portion 207 reflects light emitted from the light-emitting element 202. That is, the upper surface of the light-reflecting portion 207 attached to the inner surface 206b functions as a reflective surface. In the following description, the reflection of light at the upper surface (i.e., the reflective 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, mirrorly reflects) the light emitted from the light-emitting element 202. In the following explanation, the light traveling from the light-emitting element 202 to the light-reflecting part 207 will be referred to as incident light 211, and the light after the incident light 211 has been reflected will be referred to as reflected light 212.

[0035] The light-emitting element 202 is positioned to emit light toward a region 207a of the light-reflecting portion 207 that includes the portion covering the center 206e of the diaphragm 206, when the diaphragm 206 is not in contact with the biological surface. When the diaphragm 206 is not in contact with the biological surface, the diaphragm 206 is flat. In this embodiment, as described above, an LED that emits diffuse light is used as the light-emitting element 202. Therefore, the chestpiece 110 has a diaphragm portion 209 that narrows the light emitted from the light-emitting element 202. The diaphragm portion 209 ensures that only a portion of the light emitted from the light-emitting element 202 enters the light-reflecting portion 207. In the example in Figure 2, the portion of the holding member 201 in which the opening is formed corresponds to the diaphragm portion 209.

[0036] In this embodiment, a component that emits diffused light was 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 region 207a. If the light-emitting element 202 is a component that emits linear light, the aperture portion 209 may be omitted. Also, in this embodiment, the portion of the holding member 201 in which an opening is formed was described as an example of the aperture portion 209. However, it may be a one-sided aperture instead of an opening. In that case, for example, a light-shielding wall for narrowing one side (upper or lower) of the light emitted from the light-emitting element 202 would be provided instead of an opening.

[0037] The light-receiving element 204 is positioned to receive reflected light 212. Specifically, the light-receiving element 204 is positioned so that the amount of reflected light 212 received changes due to the 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 biological surface (i.e., when the diaphragm 206 is flat), it receives more light in the reflected light 212 compared to when the diaphragm 206 is vibrating. In other words, 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. This principle will be described later.

[0038] The chestpiece 110 has an aperture portion 210 that narrows the light specularly reflected by the light reflecting portion 207. The aperture portion 210 suppresses diffusely reflected light from entering the photodetector 204, and allows at least a portion of the light from the light reflecting portion 207 (i.e., primary reflected light) to reach the photodetector 204. In the example in Figure 2, the portion of the holding member 201 in which the opening is formed is the aperture portion 210 and It functions in this way. In this embodiment, the portion of the holding member 201 in which an opening is formed was described as an example of a diaphragm 210, but it may be a diaphragm on one side instead of an opening. In that case, for example, a light-shielding wall to narrow one side (upper or lower) of the light from the light-reflecting portion 207 would be provided instead of an opening.

[0039] A housing 208 is attached to the outer periphery of the retaining member 201. The housing 208 covers the light-emitting circuit board 203 and the light-receiving circuit board 205, and also suppresses ambient noise from entering the housing 208. The outer edge of the diaphragm 206, the outer edge of the retaining member 201, and the outer edge of the housing 208 substantially coincide with each other in a plan view with respect to the contact surface 206a of the diaphragm 206 when the diaphragm 206 is not in contact with the biological surface. In this embodiment, the housing 208 is made of metal, and the ground of the circuit boards in the chestpiece 110 (e.g., the light-emitting circuit board 203 and the light-receiving circuit board 205) is electrically connected to the housing 208. This stabilizes the ground potential.

[0040] The diaphragm 206 is fixed to the retaining member 201, forming an internal space 213 surrounded by the diaphragm 206 and the retaining member 201. The internal space 213 is sealed to prevent the light-receiving element 204 from receiving light other than that emitted by the light-emitting element 202. Furthermore, the diaphragm 206 and the retaining member 201 have light-shielding properties to prevent the light-receiving element 204 from receiving light other than that emitted by the light-emitting element 202. In the example in Figure 2, the fixing portion 206c of the diaphragm 206 is fixed to the retaining member 201. Alternatively, in the example in Figure 2, the fixing portion 206c of the diaphragm 206 may be fixed to the housing 208.

[0041] [Example of operation of the electronic stethoscope in the first embodiment] The operation of the chestpiece 110 of the electronic stethoscope 100 will be explained with reference to Figures 3A to 3D. Figures 3A and 3B show the state in which the diaphragm 206 is not pressed (i.e., is flat), and Figures 3C and 3D show the state in which the diaphragm 206 is pressed by the biological surface 320. In Figures 3A and 3C, the lower part shows a cross-sectional view of the chestpiece 110, and the upper part shows a plan view of the chestpiece 110. In the cross-sectional view of the chestpiece 110, the light-emitting circuit board 203, the light-receiving circuit board 205, and the housing 208 are omitted, and the shape of the holding member 201 is shown in detail. In the plan view of the chestpiece 110, only the light-emitting element 202, the light-receiving element 204, the light-reflecting part 207, the light-shielding wall 304, and the light-shielding wall 305 are shown. Figures 3B and 3D are perspective views focusing on the light-emitting element 202, the light-receiving element 204, the light-reflecting part 207, the light-shielding wall 304, and the light-shielding wall 305.

[0042] As shown in Figures 3A and 3C, the chestpiece 110 is used in contact with the biological surface 320 to be detected. 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 the detection target. As a result, the biological surface 320, the diaphragm 206, and the light reflecting part 207 vibrate together. Therefore, the chestpiece 110 detects the displacement of the inner surface 206b, i.e., the displacement of the upper surface of the light reflecting part 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 bodily movements such as heartbeat and breathing of the person having the biological surface 320.

[0043] As shown in Figures 3A and 3B, the light-emitting element 202 and the light-receiving element 204 are arranged such that, when the diaphragm 206 is flat, more reflected light 212 is received by the light-receiving element 204 compared to when the diaphragm 206 is vibrating. The light-receiving element 204 amplifies and outputs a photocurrent corresponding to the amount of light it receives. The peripheral circuit of the light-receiving circuit board 205 generates an output value obtained by converting the photocurrent output from the light-receiving element 204 into a voltage, generates an output value as a displacement signal, converts this 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, which reflects the state and deformation of the diaphragm 206 at any given time.

[0044] As shown in Figures 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 part 207 decreases. Consequently, the region of the light-reflecting part 207 that the incident light 211 reaches 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 photodetector 204 decreases, and the value of the displacement signal generated by the photodetector circuit board 205 becomes smaller.

[0045] In the chestpiece 110 shown in Figures 3A to 3D, the light-shielding wall 304 with an opening 306 functions as an aperture 209 on the incident light 211 side, and the light-shielding wall 305 with an opening 307 functions as an aperture 210 on the reflected light 212 side. In particular, the upper part of the upper edge of the opening 306 of the light-shielding wall 304 corresponds to the first aperture. Therefore, a portion 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 portion 207. Also, at least a portion of the light specularly reflected by the light-reflecting portion 207 is blocked by the light-shielding wall 305, depending on the position of the light-reflecting portion 207. In this embodiment, both the opening 306 and the opening 307 are rectangular. In the following explanation, of the four sides of each of the openings 306 and 307, the side parallel to the diaphragm 206 and closer to the diaphragm 206 will be referred to as the bottom side, the side parallel to the diaphragm 206 and further away from the diaphragm 206 will be referred to as the top side, the side to the left when viewed from the light-emitting element 202 will be referred to as the left side, and the side to the right when viewed from the light-emitting element 202 will be referred to as the right side.

[0046] In Figures 3A to 3D, the incident light 211 and reflected light 212 represent the light beams reaching the photodetector 204. In Figure 3B, some of the light 310 emitted from the light-emitting element 202 passes through the opening 306 of the light-shielding wall 304 and is reflected by the light-reflecting part 207 to become light 311, but is blocked by the part of the light-shielding wall 305 above the reflected light 212 and does not reach the photodetector 204. The same is true in Figure 3D.

[0047] As shown in Figures 3A and 3B, the portion of the light-reflecting part 207 that the incident light 211 reaches when the diaphragm 206 is not pressed by the biological surface 320 is referred to as the effective range 300. The effective range 300 is the portion of the light-reflecting part 207 that reflects light that reaches the photodetector 204. When the diaphragm 206 is not pressed by the biological surface 320, the effective range 300 is equal to the range to which light from the light-emitting element 202 reaches. In this embodiment, the effective range 300 is a rectangular area. 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 outside the effective range 300. In the following description, a part of the boundary line is also referred to as the boundary line.

[0048] Of the four line segments that constitute the boundary of the effective range 300, the line segment containing the position furthest from the light-emitting element 202 in the x-axis direction is denoted as the far boundary line 300a. The portion of the incident light 211 that reaches the far boundary line 300a is denoted 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 section 207 that is the longest. The angle of incidence of the incident light 211 to the light-reflecting section 207 is at its maximum value of 303a at a position on the far boundary line 300a.

[0049] Of the four line segments that constitute the boundary of the effective range 300, the line segment containing the position closest to the light-emitting element 202 in the x-axis direction is denoted as the near boundary 300b. The portion of the incident light 211 that reaches the near boundary 300b is denoted as the near incident light 211b. Near incident light 211b means that it includes the portion where the optical path from the light-emitting element 202 to the light-reflecting part 207 is shortest. The incident angle of the incident light 211 to the light-reflecting part 207 is at its minimum value of 303b at the position on the near boundary 300b. Of the light emitted from the light-emitting element 202, far incident light 211a and near incident light 211b Light that is not contained between 11b and the light is attenuated by being reflected multiple times by the light-shielding wall 304.

[0050] Of the four line segments that constitute the boundary of the effective range 300, the two line segments other than the far boundary 300a and the near boundary 300b are referred to as the lateral boundary 300c and lateral boundary 300d. The lateral boundary 300c is located to the right of the effective range 300 as viewed from the light-emitting element 202, and the lateral boundary 300d is located to the left of the effective range 300 as viewed from the light-emitting element 202.

[0051] As shown in Figures 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-illuminated region 301. The light-illuminated region 301 is the portion of the light-receiving element 204 that reaches the light emitted from the light-emitting element 202 and specularly reflected by the light-reflecting portion 207. In addition to the light specularly reflected by the light-reflecting portion 207, scattered light may also reach the light-receiving element 204, but in this embodiment, the region formed by specularly reflected light is defined as the light-illuminated region. The amount of light reaching the light-receiving element 204 is proportional to the area of ​​the light-illuminated region 301. In this embodiment, the light-illuminated region 301 is a rectangular region. The outer periphery of the light-illuminated region 301 is referred to as the boundary line of the light-illuminated region 301. The boundary line of the light-illuminated region 301 is located between the light-illuminated region 301 and the region other than the light-illuminated region 301.

[0052] Of the four line segments that constitute the boundary of the light-illuminated area 301, the line segment formed by light that is narrowed by the aperture 209 and specularly reflected by the light-reflecting part 207 is referred to as the lower boundary line 301a. Of the four line segments that constitute the boundary of the light-illuminated area 301, the line segment on the opposite side of the lower boundary line 301a is referred to as the upper boundary line 301b. The lower boundary line 301a is an example of a boundary line formed by light that is narrowed by the aperture 209 and specularly reflected by the light-reflecting part 207. The lower boundary line 301a is a boundary line that moves in accordance with the displacement of the contact surface 206a, as will be described later. In this embodiment, the area of ​​the light-illuminated area 301 changes as the lower boundary line 301a moves, and the output of the light-receiving element 204 changes. This makes it possible to accurately measure the displacement of the object to be detected. The upper boundary line 301b is an example of a boundary line that does not move in accordance with the displacement of the contact surface 206a and whose length does not change even if the contact surface 206a is displaced.

[0053] Of the four line segments that constitute the boundary of the light-irradiated area 301, the two line segments other than the lower boundary 301a and the upper boundary 301b are referred to as the lateral boundary 301c and lateral boundary 301d. The lateral boundary 301c is located to the right of the light-irradiated area 301 as viewed from the light-emitting element 202, and the lateral boundary 301d is located to the left of the light-irradiated area 301 as viewed from the light-emitting element 202. The lateral boundary 301c and lateral boundary 301d are examples of boundary lines that do not move in accordance with the displacement of the contact surface 206a, as will be described later, and whose length changes when the contact surface 206a is displaced.

[0054] Light passing through the aperture 306 along its upper edge is specularly reflected by the light reflecting section 207 and then reaches the lower boundary line 301a of the light-illuminating area 301 of the light-receiving element 204 without being obstructed by the light-shielding wall 305. Therefore, the upper edge of the aperture 306 defines the lower boundary line 301a of the light-illuminating area 301. On the other hand, light passing through the aperture 306 along its lower edge is specularly reflected by the light reflecting section 207 and then obstructed by the light-shielding wall 305, and does not reach the light-receiving element 204. Therefore, the lower edge of the aperture 306 does not define the light-illuminating area 301. Consequently, the near incident light 211b is not stopped by the aperture section 209. Alternatively, the light passing through the aperture 306 along its lower edge may be specularly reflected by the light reflecting section 207 and then reach the light-receiving element 204 without being obstructed by the light-shielding wall 305. In this case, the lower edge of the aperture 306 defines the light irradiation area 301. In this configuration, the displacement signal remains constant from zero to a predetermined value as the displacement of the diaphragm 206 decreases. Subsequently, when the lower edge of the aperture 306 no longer defines the light irradiation area 301, the displacement signal begins to decrease monotonically.

[0055] After passing through the aperture 306 and undergoing specular reflection by the light reflecting section 207, the light opens along the upper edge of the aperture 307. Light passing through 307 reaches the upper boundary line 301b of the light-illuminating area 301 of the photodetector 204. Therefore, the upper edge of the aperture 307 defines the upper boundary line 301b of the light-illuminating area 301. In other words, the upper edge of the aperture 307 is an example of an aperture that narrows the light that has been specularly reflected by the light-reflecting part 207. On the other hand, light does not pass through the part along the lower edge of the aperture 307 because it is blocked by the light-shielding wall 304. Therefore, the lower edge of the aperture 307 does not define the light-illuminating area 301.

[0056] As shown in Figures 3A and 3C, the lateral boundary lines 301c and 301d of the light-irradiated area 301 are defined by the right and left sides of the aperture 307. Alternatively, the lateral boundary lines 301c and 301d of the light-irradiated area 301 may be defined by the right and left sides of the aperture 306.

[0057] The reflected light of the far incident light 211a is referred to as the lower end reflected light 212a. The lower end reflected light 212a is the light that is located furthest down in the z-axis direction of the reflected light 212 (i.e., the part closest to the diaphragm 206). The lower end reflected light 212a reaches the lower boundary line 301a of the light irradiation region 301. The lower boundary line 301a is formed by light that has been narrowed by the aperture 209 and specularly reflected by the light reflecting part 207. The lower end reflected light 212a is away from each side of the aperture 307. That is, the lower end reflected light 212a is not narrowed by the aperture 210. In the configurations of Figures 3A and 3B, the lower boundary line 301a includes the position in the light irradiation region 301 that is closest to the diaphragm 206 in the direction normal to the diaphragm 206 (i.e., in the z-axis direction) when the diaphragm 206 is not being pressed by the biological surface 320. Furthermore, in the configurations of Figures 3A and 3B, the lower boundary line 301a includes the position in the light irradiation area 301 where the light with the maximum reflection angle at the light reflecting portion 207 reaches. This maximum reflection angle is equal to the maximum incident angle 303a. Moreover, in the configurations of Figures 3A and 3B, the lower boundary line 301a includes the position furthest from the light-emitting element 202 in a plan view relative to the diaphragm 206 when it is not being pressed.

[0058] The reflected light from the near incident light 211b is denoted as the upper end reflected light 212b. The upper end reflected light 212b is the light that is located furthest upward in the z-axis direction of the reflected light 212 (i.e., the portion furthest from the diaphragm 206). The upper end reflected light 212b reaches the upper boundary line 301b of the light irradiation region 301. In the configurations of Figures 3A and 3B, the upper boundary line 301b includes the position in the light irradiation region 301 that is furthest from the diaphragm 206 in the direction normal to the diaphragm 206 (i.e., in the z-axis direction) when the diaphragm 206 is not pressed. Also, in the configurations of Figures 3A and 3B, the upper boundary line 301b includes the position in the light irradiation region 301 that reaches the light with the minimum reflection angle at the light reflecting part 207. This minimum reflection angle is equal to the minimum incident angle 303b. Furthermore, in the configurations of Figures 3A and 3B, the upper boundary line 301b includes the position closest to the light-emitting element 202 in a plan view relative to the diaphragm 206 when it is not being pressed.

[0059] As shown in Figures 3C and 3D, when the diaphragm 206 is pressed against the biological surface 320, the positions of the effective range 300, the far boundary line 300a, the near boundary line 300b, the light irradiation area 301, the lower boundary line 301a, and the upper boundary line 301b change, respectively. Of the reflected light 212, the portion furthest from the light-emitting element 202 in the x-axis direction is called the lower end reflected light 212a. The lower end reflected light 212a reaches the lower boundary line 301a of the light irradiation area 301. As described above, the lower boundary line 301a is defined by the upper edge of the opening 306 of the aperture portion 209 on the light-emitting element 202 side. The lower boundary line 301a moves in accordance with the displacement of the contact surface 206a due to the elastic deformation of the diaphragm 206, and as a result, the area of ​​the light irradiation area 301 changes, and the output of the photodetector 204 also changes, as will be described later.

[0060] The lower boundary line 301a is displaced by a displacement ratio G relative to the displacement of the diaphragm 206. Of the reflected light 212, the one furthest from the light-emitting element 202 (in three-dimensional space, regardless of the x-axis direction) The position where the portion reaches the light-receiving element 204 is also displaced by a displacement ratio G. The displacement ratio G has a value corresponding to the angle of incidence of the incident light 211 to the light-reflecting portion 207 and the angle of the light-receiving surface of the light-receiving element 204 relative to the light-reflecting portion 207. The chestpiece 110 may be configured such that the displacement ratio G is greater than 1.5, or it may be configured such that the displacement ratio G is greater than 2.

[0061] As shown in Figures 3A to 3D, the upper boundary line 301b is defined by the portion of the light-shielding wall 305 above the reflected light 212, and is a boundary line that does not move in accordance with the displacement of the contact surface 206a and whose length does not change even if the contact surface 206a is displaced. The portion of the light-shielding wall 304 below the incident light 211 does not need to shield the light emitted from the light-emitting element 202. For example, the portion of the light-shielding wall 304 below the incident light 211 does not need to be provided. Also, the lower boundary line 301a is defined by the portion of the light-shielding wall 304 above the incident light 211. Therefore, the portion of the light-shielding wall 305 below the reflected light 212 does not need to shield the light specularly reflected by the light-reflecting portion 207. For example, the portion of the light-shielding wall 305 below the reflected light 212 does not need to be provided.

[0062] [Changes in the range of reflected light in the electronic stethoscope in the first embodiment] Referring to Figure 3E, the changes in the light-irradiated area 301 formed by the reflected light 212 that reaches the light-receiving surface of the photodetector 204 will be explained. Figure 3E shows a plan view of the photodetector 204 with respect to the light-receiving surface. The left side of Figure 3E shows the position of the light-irradiated area 301 when the diaphragm 206 is not pressed. The right side of Figure 3E shows the position of the light-irradiated area 301 when the diaphragm 206 is pressed by the biological surface 320.

[0063] To illustrate direction, the coordinate system CS' is shown in Figure 3E. The coordinate system CS' is a two-dimensional Cartesian coordinate system with mutually orthogonal x' and y' axes. 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 explanation, the positive x' axis direction is referred to as "up," and the negative x' axis direction is referred to as "down."

[0064] The surface of the light-receiving element 204 that faces the internal space 213 becomes 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 a 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 represented as side 204a.

[0065] The area of ​​the light-irradiated region 301 is defined by the lower boundary line 301a, the upper boundary line 301b, and the lateral boundary lines 301c and 301d. As shown in Figure 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, the lateral boundary lines 301c and 301d do not move substantially 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 if the contact surface 206a is displaced. On the other hand, the lengths of the lateral boundary lines 301c and 301d change when the contact surface 206a is displaced.

[0066] When the area of ​​the light-illuminated 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 a flat state, the shorter 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 smaller the area of ​​the light-illuminated region 301. Therefore, the greater the displacement of the diaphragm 206 from a flat state, the less light the light-receiving element 204 receives. Accordingly, the signal output from the light-receiving element 204 also becomes smaller. The amount of movement of the lower boundary line 301a accompanying the movement of the light-reflecting part 207 is This is greater than the amount of movement of the upper boundary line 301b that is associated with it.

[0067] As shown in Figure 3E, the change in the light-irradiated region 301 in the x' axis direction is greater than the change in the light-irradiated region 301 in the y' axis direction. Therefore, in order to increase the dynamic range of the photodetector 204, it is preferable to make the width of the photodetector 204 in the x' axis direction greater than the width of the photodetector 204 in the y' axis direction. More specifically, it is preferable that the width of the photodetector 204 in the x' axis direction be three times or more the width of the photodetector 204 in the y' axis direction.

[0068] [Relationship between displacement amount on the biological surface of the electronic stethoscope and displacement signal in the first embodiment] Referring to Figure 4, the relationship between the displacement of the biological surface 320 and the displacement signal will be explained. The displacement signal is the voltage output from the light-receiving circuit board 205. Graph 400 in Figure 4 shows the relationship between the displacement of the biological surface 320 [mm] and the displacement signal [V]. The horizontal axis of graph 400 represents the displacement of the biological surface 320, and the vertical axis of graph 400 represents the displacement signal generated by the light-receiving circuit board 205.

[0069] As described above, the displacement of the biological surface 320 is equal to the displacement of the upper surface of the light reflecting part 207. The displacement of the upper surface of the light reflecting part 207 is equal to the displacement of the diaphragm 206 (inner surface 206b). As shown in Figure 4, as the displacement of the reflected light 212 increases, the amount of reflected light 212 that reaches the photodetector 204 decreases monotonically and linearly. Therefore, if the displacement of the biological surface 320 is d and the value of the displacement signal is S, S=Vmax-k×d…(Formula 1) This is the result. Here, Vmax is the value of the displacement signal when the displacement d is zero. Vmax is determined by the amount of light emitted by the light-emitting element 202 and the sensitivity of the photodetector 204. The sensitivity of the photodetector 204 refers to the change in output voltage per unit amount of light incident on the photodetector 204. Vmax is larger the higher the sensitivity of the photodetector 204. Also, Vmax is larger the higher the amount of light emitted by the light-emitting element 202. k is the amplification factor of the photodetector 204. k is also determined by the amount of light emitted by the light-emitting element 202 and the sensitivity of the photodetector 204. k is larger the higher the sensitivity of the photodetector 204. Also, k is larger the higher the amount of light emitted by the light-emitting element 202.

[0070] The displacement amount d at which the displacement signal S becomes zero is denoted as dmax. For example, dmax is 1 mm. As the displacement amount d of the biological surface 320 increases, the area of ​​the light-irradiated region 301 decreases and becomes zero. When the area of ​​the light-irradiated region 301 becomes zero, the displacement signal S also becomes zero. The displacement amount d at which the area of ​​the light-irradiated region 301 becomes zero is determined by the respective positions of the light-receiving element 204 and the aperture portion 210 relative to the reflected light 212.

[0071] When the displacement d exceeds dmax, the reflected light 212 no longer reaches the photodetector 204, so even if the displacement d increases, the displacement signal S remains zero. Therefore, the chestpiece 110 is configured such that the displacement d is in the range of 0 or more and dmax or less within the range in which the vibration of the diaphragm 206 is expected (this is referred to as the operating range of the diaphragm 206). As shown in Graph 400, the light-emitting element 202 and the photodetector 204 are arranged such that the amount of light reaching the photodetector 204 (amount of light received) changes monotonically in response to the movement of the light-reflecting part 207 in one direction within the operating range of the diaphragm 206. In the example in Figure 4, the photodetector 204 is arranged so that the amount of light received decreases monotonically, but the photodetector 204 may also be arranged so that the amount of light received monotonically increases.

[0072] In this embodiment, the light-emitting element 202 and the light-receiving element 204 are arranged such that all of the reflected light 212 reaches the light-receiving element 204 when the diaphragm 206 is flat. Alternatively, when the diaphragm 206 is displaced below flat, the reflected light 212 The light-emitting element 202 and the light-receiving element 204 may be arranged so that all of them reach the light-receiving element 204.

[0073] In the embodiment described above, 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 of 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 this case, the light-receiving surface will be parallel to the diaphragm 206.

[0074] With the above configuration, the chestpiece 110 according to the first embodiment functions as a detection device capable of accurately detecting the displacement and vibration of the biological surface 320. Specifically, in the chestpiece 110 described above, when the biological surface, which is an example of the detection target, is in close contact with the diaphragm 206, a displacement signal is generated based on the amount of displacement of the biological surface 320, which vibrates together with the diaphragm 206. Therefore, the displacement of the biological surface 320 can be accurately detected regardless of the frequency at which the biological surface 320 vibrates. For example, even displacement of the biological surface 320 due to low-frequency vibrations of about 10 Hz can be accurately detected. Such low-frequency vibrations are included in sounds (e.g., heart sounds) emitted by vibrations propagated from inside the body by the heartbeat. In the chestpiece 110, the displacement signal does not change unless the diaphragm 206 is displaced. Therefore, ambient sound and vibrations or accelerations due to the movement of the chestpiece 110 are not detected as noise, and a high S / N ratio output characteristic can be obtained.

[0075] [Hardware configuration of the electronic stethoscope in the first embodiment] Referring to Figure 5, an example of the hardware configuration of the electronic stethoscope 100 will be described. Figure 5 is a diagram showing an example of the hardware configuration of the electronic stethoscope 100 according to the first embodiment. The electronic stethoscope 100 includes a chestpiece 110 as a detection device for detecting the displacement and vibration of the biological surface 320 described above, a sound output unit 510, a calibration execution unit 520, and a determination unit 530.

[0076] The sound output unit 510 is realized by multiple circuit elements mounted on a circuit board included in the gripping unit 120. These multiple circuit elements include a processor. The processor constituting the sound output unit 510 transmits a sound signal based on the 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 biological sound of a living organism (e.g., a human) with a biological surface 320, and is therefore also called a biosound signal. Both the displacement signal and the sound signal (biosound signal) are waveform signals. The sound signal is transmitted to a sound output device 540, such as earphones or headphones. Simultaneously with the transmission to the sound output device 540, the sound signal is also transmitted to a computer 550 (e.g., a personal computer, smartphone, tablet, etc.). Users such as doctors, nurses, and public health nurses can listen to the biological sound represented by the digitally converted sound signal using the sound output device 540 or the computer 550. The sound output device 540 is, for example, a wired or wireless earphone or headphones.

[0077] The sound output unit 510 is a sound signal generation unit that generates sound signals (biometric signals) based on the displacement signals generated by the chestpiece 110. The sound output unit 510 is compliant with the earphones or headphones described above and can transmit sound signals via both wireless and wired communication. The sound output unit 510 can be configured with filters and amplifiers for filtering and amplifying the displacement signals output from the chestpiece 110, and an A / D converter for digitizing the output.

[0078] Furthermore, the sound output unit 510 may also include a wired communication unit such as an AUX terminal, or a wireless communication unit compliant with a wireless communication standard such as Bluetooth®. For example, the sound signal generated by filtering and amplifying the displacement signal is transmitted to the sound output device via the wired communication unit. The system may be configured to provide signals to the 540 and the computer 550. Alternatively, for example, the system may be configured so that the sound signal generated by filtering, amplifying, and digitizing the displacement signal is provided to the sound output device 540 and the computer 550 via the wireless communication unit. The electronic stethoscope 100 may be capable of outputting sound signals via both wireless and wired communication, or it may be capable of outputting sound signals via only one of these communication methods. The sound output device 540 may also be considered as part of the electronic stethoscope 100. Furthermore, some or all of the components of the sound output unit 510 may be provided within the chestpiece 110.

[0079] The computer 550 can also visually display waveform data generated based on the sound signal. The waveform data may be generated by the computer 550 or by the electronic stethoscope 100. In addition, some or all of the signal processing and sound output processing by the electronic stethoscope 100 may be performed by an external device (e.g., a sound output device 540 or the computer 550).

[0080] The calibration execution unit 520 is a calibration execution means that accurately detects the displacement and vibration of the biological surface 320 and performs calibration to obtain biological signals and sound signals with high accuracy. Details of the calibration will be described later. The determination unit 530 is a determination means that performs various determination operations on the displacement signal generated by the chestpiece 110 and the sound signal generated by the sound output unit 510. The determination result of the determination unit 530 is used for operations such as calibration. The calibration execution unit 520 and the determination unit 530 are each configured to include a processor. The processors that make up the sound output unit 510, the calibration execution unit 520, and the determination unit 530 may be common to each other, or they may each be provided independently.

[0081] The electronic auscultation device 100 can accurately detect the 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 heart sounds emitted by the body due to heartbeat, and relatively high-frequency biological sounds emitted by the body due to respiration. Respiratory sounds are biological vibrations that include a frequency band (first frequency band) containing components in the frequency range of 500 Hz to 1 kHz, for example. Heart sounds are biological vibrations that include a frequency band (second frequency band) containing components in the frequency range of 30 Hz to 300 Hz, for example.

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

[0083] Furthermore, under certain conditions, such as when not in use, the electronic stethoscope 100 automatically switches to a power-saving mode that consumes less power than the heart sound mode or respiratory sound mode. In power-saving mode, for example, the power supplied to the light-emitting element 202 and the light-receiving element 204 is less than in auscultation mode. When any operation is performed on the electronic stethoscope 100, it switches (returns) from power-saving mode to auscultation mode. Alternatively, the electronic stethoscope 100 may be configured to automatically turn off if the power-saving mode continues for a certain period of time or longer.

[0084] The control unit 123 is equipped with a volume up button 123a and a volume down button 123b, which are volume adjustment buttons for adjusting the gain of the displacement signal output by the electronic stethoscope 100. The volume up button 123a and the volume down button 123b are used to adjust the volume of the sound output by the electronic stethoscope 100. Furthermore, the display unit 122 of the electronic stethoscope 100 is equipped with an LED as an indicator to show whether the current auscultation mode is heart sound mode or respiratory sound mode. The user can visually confirm whether the operating mode is heart sound mode or respiratory sound mode by the state of illumination of this LED. Note that heart sound mode and respiratory sound mode are examples of auscultation modes.

[0085] [Variation of displacement signals] Using Figures 6A and 6B, the variation in the displacement signal, which is the voltage output from the light-receiving circuit board 205, will be illustrated. Graph 410 in Figure 6A shows the relationship between the displacement amount [mm] of the biological surface 320 and the displacement signal [V]. The horizontal axis of graph 410 represents the displacement amount of the biological surface 320 and the displacement signal generated by the light-receiving circuit board 205.

[0086] As described above, the electronic auscultation device 100 is an optical displacement type auscultation device. In such a device, variations occur in the displacement signal, which is the output value, due to mechanical and optical factors. In Figure 6A, the ideal line L1, which shows the ideal relationship between the displacement amount of the biological surface 320 and the displacement signal, is represented by a thick line. Also in Figure 6A, the lines that occur when the relationship between the displacement amount of the biological surface 320 and the displacement signal deviates from the ideal line L1 due to mechanical factors are represented by dotted lines. Due to mechanical factors, the dotted line L2 is where the displacement signal when the displacement amount is zero is greater than the ideal line L1, and the dotted line L3 is where it is smaller. Also in Figure 6A, the lines that occur when the relationship between the displacement amount of the biological surface 320 and the displacement signal deviates from the ideal line L1 due to mechanical and optical factors are represented by dashed lines. Due to mechanical and optical factors, the dashed line L4 is where the displacement signal when the displacement amount is zero is greater than the ideal line L1, and the dashed line L5 is where it is smaller. In this example, dotted lines L2, L3, dashed lines L4, and L5 are parallel to the ideal line L1.

[0087] Among the factors contributing to the variation in the displacement signal, mechanical factors include dimensional tolerances and assembly tolerances of the components constituting the holding member 201, light-emitting element 202, light-receiving element 204, diaphragm 206, and light-reflecting part 207. Optical factors also contribute to the variation in the displacement signal, including variations in optical characteristics. Variations in optical characteristics include, for example, variations in the light emission characteristics of the light-emitting element 202 (a light-emitting diode) and variations in the light-receiving sensitivity of the light-receiving element 204 (a photosensor). Since the displacement of the biological surface 320 is minute, it is crucial to suppress variations in the displacement signal due to mechanical and optical factors in order to accurately detect vibrations of the biological surface 320.

[0088] One method for suppressing variations in displacement signals due to mechanical factors is to manufacture the electronic stethoscope 100 by assembling each component in a way that corrects assembly tolerances. Graph 420 in Figure 6B shows the relationship between the displacement amount [mm] of the biological surface 320 and the displacement signal [V] when each component is assembled in a way that corrects assembly tolerances. Figure 6B shows the ideal line L1, dotted line L2, dotted line L3, dashed-dotted line L4, and dashed-dotted line L5, similar to Figure 6A.

[0089] Figure 6B shows an example where the position of the diaphragm 206 in the z-axis direction is adjusted so that the output value of the photodetector 204 becomes zero when the displacement of the biological surface 320 is dmax. When the electronic stethoscope 100 is assembled while adjusting the position of the diaphragm 206 in this way, the variation in the displacement signal decreases, and the dotted lines L2, L3, dashed-dotted line L4, and dashed-dotted line L5 approach the ideal line L1. Figure 6B shows an example where the dotted line L2 coincides with the ideal line L1 due to correction during assembly.

[0090] On the other hand, unlike mechanical factors, variations in displacement signals due to optical factors are difficult to correct during assembly. This is because optical factors include variations in the amount of light emitted by the light-emitting element 202 and the amount of light received by the light-receiving element 204 due to individual differences in light-emitting diodes and light sensors, as well as changes in the amount of light emitted due to the aging degradation of the light-emitting element 202. Therefore, the electronic stethoscope 100 is configured to perform calibration to suppress variations in displacement signals due to optical factors, that is, to reduce the difference between the ideal line L1 and the dashed-dotted line L4, and between the ideal line L1 and the dashed-dotted line L5.

[0091] [Circuit configuration of the electronic stethoscope in the first embodiment] Referring to Figure 7, an example of the overall circuit configuration of the electronic stethoscope 100 will be explained. Figure 7 is a diagram showing an example of the overall circuit configuration of the electronic stethoscope 100. The circuit 600 of the electronic stethoscope 100 is composed of a light-emitting circuit board 203 and a light-receiving circuit board 205 provided on the chestpiece 110, a circuit board provided on the gripping part 120, etc. Note that Figure 7 shows only the main components of the circuit configuration and does not necessarily show all the components necessary for the circuit to be complete.

[0092] Circuit 600 includes a processor 601, a high-pass filter (hereinafter referred to as HPF) 602, and an amplifier / low-pass filter (hereinafter referred to as LPF) 603. Circuit 600 also includes a battery 604, a DC / DC converter (hereinafter referred to as DC / DC) 605, an LDO regulator (hereinafter referred to as LDO) 606, a load switch (hereinafter referred to as SW) 607, and an LDO regulator (hereinafter referred to as LDO) 608.

[0093] The processor 601 is a control unit that controls the operation of the electronic stethoscope 100 by executing a program stored in, for example, non-volatile memory (not shown). The processor may also constitute a microcontroller together with non-volatile memory, RAM, a Bluetooth circuit that controls a wireless communication unit compliant with the Bluetooth® wireless communication standard, etc. The processor 601 may also be used as a processor that constitutes the calibration execution unit 520 or the determination unit 530.

[0094] Battery 604, DC / DC 605, LDO 606, load SW 607, and LDO 608 constitute the power supply unit of the electronic stethoscope 100. Battery 604 stores the electrical energy used by the electronic stethoscope 100. Battery 604 has a protection function that cuts off the current when the current flowing through it exceeds a predetermined threshold, thereby protecting the battery 604. DC / DC 605 is connected to battery 604 and is a converter for boosting the DC voltage to another DC voltage. LDO 606 is a low-loss regulator that takes the voltage from DC / DC 605 as input, and LDO 608 is a low-loss regulator that takes the voltage from load SW 607 as input. LDO 606 and LDO 608 are provided to generate the operating voltages for some circuit elements of the electronic stethoscope 100. Load SW 607 is a switch for turning the power supply from battery 604 on and off. The DC / DC605 and load SW608 are connected to the processor 601 and driven and controlled.

[0095] Figure 7 shows an example where the voltage of battery 604, +VA (e.g., 3.7V), is boosted to voltage +VB (e.g., +6.8V) by DC / DC605. Figure 7 also shows an example where the output of LDO606, which receives the voltage +VB from DC / DC605 as input, is voltage +VC (e.g., +3.3V), and the output of LDO608, which also receives the voltage +VB from DC / DC605 as input, is voltage +VS (e.g., +5.8V). In this way, power from battery 604 is supplied to the light-emitting element 202 and the light-receiving element 204 as voltage +VS.

[0096] The HPF602 and amplifier / LPF603 are sound output sections that process the displacement signal output by the photodetector 204 to generate sound signals representing the sound transmitted from the biological surface to the diaphragm 206. The signal processing unit (510) is configured as follows: The HPF602 attenuates the low-frequency components of the displacement signal output by the photodetector 204 and passes the high-frequency components, and outputs the resulting signal to the amplifier / LPF603. The cutoff frequency fc of the HPF602 is, for example, 10Hz. The amplifier / LPF603 amplifies the signal received from the HPF602 and attenuates the high-frequency components of the received signal, while passing the low-frequency components. The amplification factor of the amplifier / LPF603 is, for example, ×300 (300 times). In other words, the displacement signal output by the photodetector 204 is filtered and amplified by the HPF602 and the amplifier / LPF603. The processor 601 then transmits the filtered and amplified displacement signal to the sound output device 540 via wired or wireless communication. In this way, the signal processing unit can extract components of a specific frequency band contained in the displacement signal and generate an audio signal.

[0097] [Circuit configuration for performing calibration] Next, with reference to Figures 8A to 8F and Figure 9, an example of a circuit configuration for performing calibration will be described. Optical factors that cause variations in displacement signals include variations in the amount of light emitted by the light-emitting element 202 and the amount of light received by the light-receiving element 204 due to individual differences in light-emitting diodes and light sensors, as well as the aging degradation of the light-emitting element 202. Therefore, calibration to suppress variations in displacement signals due to optical factors includes correcting the amount of light emitted by the light-emitting element 202 and correcting the light-receiving sensitivity of the light-receiving element 204. The specific configuration of a circuit to achieve these corrections will be described below.

[0098] First, an example of a circuit configuration for correcting the light emission amount of the light-emitting element 202 will be described with reference to Figures 8A and 8B. Figure 8A shows an example of a circuit configuration of a light-emitting circuit board 203 for correcting the light emission amount of the light-emitting element 202. Figure 8B shows an example different from the example shown in Figure 8A, which is an example of a circuit configuration of a light-emitting circuit board 203 for correcting the light emission amount of the light-emitting element 202.

[0099] The light-emitting circuit board 203 shown in Figure 8A is an emitter follower constant current circuit that corrects the amount of light emitted by the light-emitting element 202 using the Pulse Width Modulation (PWM) method. In this example, the constant current value is adjusted by the duty cycle of the PWM signal from the processor (e.g., processor 601) of the calibration execution unit 520. The duty cycle of the PWM signal refers to the proportion of the signal that is high during one period of the signal waveform. With this configuration, it is possible to finely correct (adjust) the amount of light emitted by adjusting the duty cycle of the PWM signal. In this case, the calibration execution unit 520 corrects the amount of light emitted by the light-emitting element 202 and performs calibration.

[0100] The light-emitting circuit board 203 shown in Figure 8B is an emitter follower constant current circuit that corrects the amount of light emitted by the light-emitting element 202 in a step manner. In this example, the constant current value is adjusted by switching the resistance value of a resistor provided on the light-emitting circuit board 203 in response to a signal from the processor of the calibration execution unit 520. With this configuration, it is possible to correct the amount of light emitted in steps. In this case as well, the calibration execution unit 520 corrects the amount of light emitted by the light-emitting element 202 and performs calibration.

[0101] Next, with reference to Figures 8C and 8D, an example of a circuit configuration that can correct the resistance value of the resistor used to convert the output current of the photodetector 204 into current / voltage will be described in order to correct the light-receiving sensitivity of the photodetector 204. Figure 8C shows an example of the circuit configuration of the photodetector circuit board 205 for correcting the light-receiving sensitivity of the photodetector 204. Figure 8D shows an example different from the example shown in Figure 8C, which is an example of the circuit configuration of the photodetector circuit board 205 for correcting the light-receiving sensitivity of the photodetector 204.

[0102] The light receiving circuit board 205 shown in Figure 8C is a constant current circuit of a resistor-switching emitter follower. This is the path. In this example, the light-receiving sensitivity of the photodetector 204 is corrected by switching the resistance value for converting the output current of the photodetector 204 into current / voltage based on multiple signals from the processor of the calibration execution unit 520. In this case, the calibration execution unit 520 corrects the resistance value for converting the output current of the photodetector 204 into current / voltage, and performs calibration by correcting the light-receiving sensitivity of the photodetector 204.

[0103] The light-receiving circuit board 205 shown in Figure 8D is a constant-current circuit of a variable-resistance emitter follower. In this example, the resistor used to convert the output current of the light-receiving element 204 into current / voltage based on multiple signals from the processor of the calibration execution unit 520 is a digital potentiometer, and the light-receiving sensitivity of the light-receiving element 204 is corrected by changing the resistance value based on the signal from the processor 601. In this case as well, the calibration execution unit 520 corrects the resistance value used to convert the output current of the light-receiving element 204 into current / voltage, thereby correcting the light-receiving sensitivity of the light-receiving element 204 and performing calibration.

[0104] Next, with reference to Figures 8E and 8F, an example of a circuit configuration that can correct the resistance value of the power supply voltage of the photodetector 204 in order to correct the light-receiving sensitivity of the photodetector 204 will be described. Figure 8E shows an example of the circuit configuration of the circuit 600 for correcting the power supply voltage of the photodetector 204. Figure 8F is an example different from the example shown in Figure 8E, and shows an example of the circuit configuration of the light-receiving circuit board 205 for correcting the resistance value of the power supply voltage of the photodetector 204.

[0105] The circuit 600 shown in Figure 8E is configured to allow switching of the set value (resistive voltage divider value) of the power supply voltage of the photodetector 204 based on multiple signals from the processor of the calibration execution unit 520. In this case, the calibration execution unit 520 performs calibration by correcting the power supply voltage of the photodetector 204 and correcting the light receiving sensitivity of the photodetector 204.

[0106] Figure 8E shows an example where the voltage +VA of battery 604 is boosted to voltage +VB by DC / DC605. Figure 8E also shows an example where the output of LDO608, which receives the voltage +VB from DC / DC605, is voltage +VD, and the output of LDO609, which receives the voltage +VD from DC / DC608, is voltage +VE. Power from battery 604 is supplied to the light-emitting element 202 as voltage +VE. Alternatively, power from battery 604 can be selectively supplied to the photodetector 204 as either voltage +VD or voltage +VE.

[0107] The light-receiving circuit board 205 shown in Figure 8F has a digital potentiometer as a setting unit (resistor unit) for setting the voltage of the power supply of the light-receiving element 204 based on multiple signals from the processor of the calibration execution unit 520. This configuration makes it possible to change the resistance value based on signals from the processor. In this case, the calibration execution unit 520 performs calibration by correcting the voltage of the power supply of the light-receiving element 204 and correcting the light-receiving sensitivity of the light-receiving element 204.

[0108] The output sensitivity of the photodetector 204 will be explained with reference to Figure 9. Figure 9 is a diagram showing examples of the waveform of the displacement signal [V] output by the photodetector 204. Three examples of waveforms S1, S2, and S3 are shown in Figure 9. Waveforms S1, S2, and S3 are the waveforms of the displacement signal that are output when the biological vibration is at its maximum amplitude. Waveform S3 is a waveform in which the maximum value of the displacement signal is greater than that of waveform S2. Waveform S2 is a waveform in which the maximum value of the displacement signal is greater than that of waveform S1.

[0109] Furthermore, the graph in Figure 9 shows the manufacturing lower limit line P1, the sensitivity guarantee line P2, the unsaturated line P3, and the manufacturing upper limit line P4 as dotted lines. Each line is smallest in the order of manufacturing lower limit line P1, sensitivity guarantee line P2, unsaturated line P3, and manufacturing upper limit line P4.

[0110] The maximum value of the displacement signal of waveform S1 is greater than the manufacturing lower limit line P1 and less than the sensitivity guarantee line P2. If the output sensitivity of the photodetector 204 is less than the sensitivity guarantee line P2, sufficient biological amplitude cannot be obtained. If sufficient biological amplitude cannot be obtained, the signal-to-noise ratio (SNR), which is the ratio of signal to noise, deteriorates, and there is a risk that minute biological vibrations cannot be detected.

[0111] The maximum value of the displacement signal of waveform S2 is greater than the sensitivity guarantee line P2 and less than the unsaturation line P3. In such cases, the biosignal can be detected after configuration by the photodetector 204.

[0112] The maximum value of the displacement signal in waveform S3 is greater than the unsaturation line P3 and less than the manufacturing limit line P4. When the amplitude of the biological signal exceeds the unsaturation line P3, it saturates at the input of the A / D converter. This prevents the biological sound from being detected correctly and results in a waveform that is clamped at the unsaturation line P3 (3.3V in this example), which can cause harmonic on (noise) to be generated.

[0113] Thus, if the sensitivity guarantee line P2 is not appropriately set with respect to the displacement signal value when the biological vibration is at its maximum amplitude, there is a risk that biological sounds may not be detected correctly. The displacement signal value fluctuates, for example, depending on the amount of light emitted by the light-emitting element 202. Also, the value of the sensitivity guarantee line P2 fluctuates depending on the light-receiving sensitivity of the light-receiving element 204. Therefore, in the first embodiment, in order to suppress a decrease in the accuracy of the output of the light-receiving element 204, the electronic stethoscope 100 is configured to be able to perform calibration so that the displacement signal value when the biological vibration is at its maximum amplitude and the sensitivity guarantee line P2 have an appropriate relationship.

[0114] [Calibration process flow of the first embodiment] Referring to Figure 10, the calibration process flow in the electronic stethoscope 100 will be described. Figure 10 is a flowchart of the calibration process of the electronic stethoscope 100 according to the first embodiment. In the electronic stethoscope 100 according to the first embodiment, the calibration process flow starts when the device transitions from a power-off state to a power-on state, or when the calibration button 123d is pressed. The calibration process flow started by turning on the power will be described in detail below. In the example described below, the light intensity correction of the light-emitting element 202 is performed as calibration, but instead of light intensity correction, the light-receiving sensitivity of the photodetector 204 may be corrected, etc. Alternatively, the device may be configured to perform both light intensity correction of the light-emitting element 202 and light-receiving sensitivity correction of the photodetector 204 as calibration, and these may be used separately or in combination as needed.

[0115] The calibration process flow is preferably performed, for example, with the electronic stethoscope 100 placed on a dedicated stand in a flat state where the diaphragm 206 is not pressed. A dedicated stand on which the electronic stethoscope 100 is placed when not in use or when calibration is being performed, which fixes the gripping part 120, may also be included as a component of the electronic stethoscope 100.

[0116] When the power to the electronic stethoscope 100 is turned on and the calibration process flow starts, the first step (hereinafter referred to as S) 1001 is when the light-emitting element 202 starts to emit light.

[0117] Next, in S1002, the electronic stethoscope 100 waits for a predetermined time. In S1002, the electronic stethoscope 100 waits until the various operations associated with the startup of the electronic stethoscope 100, such as the illumination of the light-emitting element 202, have stabilized.

[0118] Calibration is preferably performed when the diaphragm 206 is not displaced and is flat. Therefore, in the first embodiment, the diaphragm is flat before performing the calibration. The system is configured to determine in S1003 whether the diaphragm 206 has been displaced, that is, whether the diaphragm 206 is located within a predetermined range. In other words, S1003 determines whether or not calibration can be performed.

[0119] In S1003, as a first determination operation, the determination unit 530 determines whether or not the biological signal is within a first range. The biological signal is an audio signal representing the biological sound of a living organism having a biological surface 320, and is a signal generated by the audio output unit 510 based on the displacement signal. The first determination operation is performed to determine whether the diaphragm 206 is located within a predetermined range and is in a state where calibration is possible. That is, the first determination operation identifies the vibration state or pressing state of the diaphragm 206 based on the biological signal and determines whether or not calibration can be performed. The first range used in the first determination operation (first upper limit TU1 and first lower limit TL1) is a predetermined range set to have a buffer over the ideal value of the biological signal when the displacement amount of the diaphragm 206 is zero.

[0120] The first determination operation may, for example, determine that the biological signal is not within the first range if the biological signal falls outside the first range at any point during a predetermined period. However, the determination method is not limited to this, and for example, the difference between the maximum and minimum values ​​of the biological signal during the predetermined period may be used, or a count value at a predetermined interval may be used instead of a predetermined period.

[0121] If it is determined in S1003 that the biological signal is within the first range, i.e., if the answer in S1003 is YES, the process proceeds to S1004. In S1004, as a second determination operation, the determination unit 530 determines whether or not the displacement signal is outside the second range. The second determination operation is performed to determine whether or not calibration is required. The second range used in the second determination operation (second upper limit TU2 and second lower limit TL2) is a predetermined range set to provide a buffer to the ideal value of the displacement signal when the displacement amount of the diaphragm 206 is zero. In this example, the second upper limit TU2 in the second determination operation is the unsaturated line P3 shown in Figure 9, and the second lower limit TL2 is the sensitivity guarantee line P2 shown in Figure 9.

[0122] If it is determined in S1004 that the displacement signal is outside the second range, i.e., if the answer in S1004 is YES, the process proceeds to S1005. In S1005, the light intensity of the light-emitting element 202 is corrected as part of the calibration. The light intensity correction may use the displacement signal used for the determination in S1004, or a new displacement signal may be acquired. After the calibration is performed in S1005, the process returns to S1002, waits for a predetermined time, and then proceeds again to S1003.

[0123] On the other hand, if it is determined in S1004 that the displacement signal is not outside the second range (i.e., within the second range), i.e., the result in S1004 is NO, then calibration is deemed unnecessary, and the process proceeds to S1008 without proceeding to S1005. In S1008, the electronic stethoscope 100 is started up normally, and the calibration process flow ends. At this time, as part of the normal startup process, if the calibration has been successfully performed, the system may notify the user that the calibration has been performed by displaying it on the display unit 122 or the like. Similarly, as part of the normal startup process, the system may be configured to display the calibration results, such as the correction amount, on the display unit 122 or the like.

[0124] Furthermore, if it is determined in S1003 that the biological signal is not within the first range (outside the first range), that is, if the result in S1003 is NO, the process proceeds to S1006. In S1006, as a third determination operation, the determination unit 530 determines whether a predetermined time has elapsed from a predetermined timing (for example, the start of the calibration processing flow). In order for the determination unit 530 to acquire the elapsed time, the determination unit 530 may be provided with a counter that starts counting at a predetermined timing, or the elapsed time may be acquired by other methods.

[0125] If it is determined in S1006 that the predetermined time has not elapsed, that is, if the answer in S1006 is NO If necessary, the process proceeds to S1003 again, and the calibration processing flow continues. On the other hand, if it is determined in S1006 that a predetermined time has elapsed, i.e., if the answer to S1006 is YES, it is determined that the calibration could not be performed, and the process proceeds to S1007 to execute timeout error processing. In the case of a timeout error, the execution of calibration is canceled. In the case of a timeout error, processing may also be performed to return the light intensity to its initial value (value before light intensity correction) or to notify the user that calibration could not be performed by displaying it on the display unit 122 or the like. Furthermore, the notification means is not limited to the display unit 122, and notification of calibration cancellation may also be sent to an external terminal or by sound. After that, the process proceeds to S1008, and the electronic stethoscope 100 is started up normally.

[0126] According to the configuration of the first embodiment, calibration can be performed in a flat (or nearly flat) state in which the diaphragm 206 is not displaced by the first determination operation based on biological signals. Therefore, calibration can be performed with high accuracy, and a decrease in the detection accuracy of displacement and vibration of the biological surface 320 can be suppressed.

[0127] The calibration process flow described above is merely an example, and the order and operation of each step can be changed as appropriate. For example, the second judgment operation in S1004 may be performed before the first judgment operation in S1003. Also, if the calibration process is started by pressing the calibration button 123d, processes such as S1001 and S1008 may be omitted.

[0128] [Calibration process example] Refer to Figures 11A to 11E to explain specific examples of calibration processes. Below, we will explain, in an illustrative manner, the calibration process for correcting the light emission amount of the light-emitting element 202.

[0129] In Figures 11A to 11E, the upper graph shows the transition of the displacement signal (contact detection signal), which is the output of the photodetector 204, and the lower graph shows the transition of the biosignal, which is the output value obtained by removing the DC component from the displacement signal and amplifying it. In the graph showing the transition of the displacement signal, the vertical axis is the displacement signal [V] and the horizontal axis is time [seconds]. In the graph showing the transition of the biosignal, the vertical axis is the biosignal [V] and the horizontal axis is time [seconds].

[0130] Let's explain Processing Example 1. Figure 11A shows Processing Example 1 of calibration in which the displacement signal is corrected stepwise with a constant correction amount. The period from time t0 to time t1 in Figure 11A is the period during which the first judgment operation S1003 and the second judgment operation S1004 in Figure 10 are executed. In this example, during the period from time t0 to time t1, the biological signal is assumed to be a constant value and within the first range of the first judgment operation (greater than or equal to the first lower limit TL1 and less than or equal to the first upper limit TU1). Also, the displacement signal is assumed to be a constant value and outside the second range (greater than the unsaturated line P3 (= second upper limit TU2)). Therefore, once the first judgment operation is completed, the process moves to the second judgment operation and it is determined that calibration is necessary.

[0131] The period from time t1 to time t2 in Figure 11A is the period during which the light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. During this period, the light intensity of the light-emitting element 202 is corrected, and the displacement signal decreases. On the other hand, since the biological signal is an amplified signal of the displacement signal, it is always at its upper limit during this period. In Processing Example 1, the amount of correction for the light intensity of the light-emitting element 202 is set to a predetermined amount. That is, each time calibration is performed, the light intensity of the light-emitting element 202 is corrected (reduced in this example) by a predetermined amount.

[0132] The period from time t2 to time t3 in Figure 11A is the period during which the first and second decision actions are executed again. In this example, during the period from time t2 to time t3, the biological The signal is assumed to be a constant value identical to the period from time t0 to time t1, and within the first range of the first decision operation (greater than or equal to the first lower limit TL1, and less than or equal to the first upper limit TU1). The displacement signal is assumed to be a constant value smaller than the period from time t0 to time t1, and outside the second range (greater than the unsaturated line P3 (= second upper limit TU2)). Therefore, once the first decision operation is completed, the system proceeds to the second decision operation again, and it is determined that calibration is required.

[0133] The period from time t3 to time t4 in Figure 11A is the period during which the second light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. Here, the light intensity correction is performed with the same amount as the correction during the period from time t1 to time t2.

[0134] The period from time t4 onwards in Figure 11A is the period during which the first judgment operation is performed again. In this example, during the period from time t4 onwards, the biosignal is assumed to be the same constant value as during the period from time t0 to time t1, and is within the first range of the first judgment operation (greater than or equal to the first lower limit TL1, and less than or equal to the first upper limit TU1). The displacement signal is assumed to be a constant value smaller than that during the period from time t2 to time t3, and is within the second range (greater than or equal to the sensitivity guarantee line P2 (= second lower limit TL2), and less than or equal to the unsaturated line P3 (= second upper limit TU2)). Therefore, once the first judgment operation is completed, the process moves back to the second judgment operation, determines that calibration is unnecessary, and the calibration process ends.

[0135] Processing Example 2 will now be explained. In the following explanation, points that are the same as in Processing Example 1 will be omitted, and points specific to Processing Example 2 will be mainly explained. Figure 11B shows Processing Example 2 of calibration in which the displacement signal is corrected by the calculated correction amount. The period from time t0 to time t1 in Figure 11B is the same as the period from time t0 to time t1 in Figure 11A. That is, after the first judgment operation is performed during this period, the second judgment operation is performed. In Processing Example 2, the electronic stethoscope 100 stores the value of the displacement signal at this time as value V1. The value V1 may be stored in a non-volatile memory provided in, for example, the calibration execution unit 520, etc. In this example as well, once the first judgment operation is completed, the process moves to the second judgment operation, and it is determined that calibration is necessary.

[0136] The period from time t1 to time t2 in Figure 11B is the period during which the light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. During this period, the light intensity of the light-emitting element 202 is corrected, and the displacement signal decreases. On the other hand, since the biological signal is an amplified signal of the displacement signal, it is always at the upper limit during this period. In processing example 2, the amount of light intensity correction of the light-emitting element 202 during the first light intensity correction is set to a predetermined amount. That is, when calibration is performed, the light intensity of the light-emitting element 202 is corrected by a predetermined amount.

[0137] The period from time t2 to time t3 in Figure 11B is the period during which the first and second judgment operations are performed again. In this example, during the period from time t2 to time t3, the biosignal is assumed to be the same constant value as during the period from time t0 to time t1, and is within the first range of the first judgment operation (greater than or equal to the first lower limit TL1, and less than or equal to the first upper limit TU1). The displacement signal is assumed to be a constant value smaller than that during the period from time t0 to time t1, and is outside the second range (less than the sensitivity guarantee line P2 (= second lower limit TL2)). Therefore, once the first judgment operation is completed, the system proceeds to the second judgment operation again, and it is determined that calibration is required. In processing example 2, the electronic stethoscope 100 stores the value of the displacement signal at this time as V2.

[0138] The period from time t3 to time t4 in Figure 11B is the period during which the light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. In processing example 2, the previously stored values ​​V1 and V2 are used to bring the displacement signal value closer to the target value Vt. In this example, the target value Vt is The midpoint between the sensitivity guarantee line P2 and the unsaturation line P3 is set to X1[%] when the displacement signal is value V1[V], the light intensity setting value when the displacement signal is value V2[V] is set to X2[%], and the target light intensity setting value when the displacement signal is the target value Vt[V] is set to Xt[%]. In this case, the target light intensity setting value Xt is, Xt=Xu+X2…(Formula 2) Xu=(X1-X2) / (V1-V2)*(Vt-V2) …(Formula 3) This is the result. Then, during the second light intensity correction, the light intensity is corrected to the target light intensity setting value Xt calculated from the above formula, and the displacement signal approaches the target value Vt. Also, the value of the biological signal at this time is smaller than the period from time t1 to time t2, and larger than the period from time t2 to time t3.

[0139] The period from time t4 onwards in Figure 11B is the same as the period from time t4 onwards in Figure 11A. In other words, the first determination operation is performed, the second determination operation determines that calibration is unnecessary, and the calibration process ends. With this calibration method, even when a large correction of light intensity is required, calibration can be completed with just two light intensity corrections.

[0140] Let's explain Processing Example 3. In the following explanation, we will omit explanations of points that are the same as in Processing Example 1, and mainly explain points that are unique to Processing Example 3. Figure 11C shows Processing Example 3 of calibration in which the displacement signal is corrected by feedback control. The period from time t0 to time t1 in Figure 11C is the same as the period from time t0 to time t1 in Figure 11A. That is, after the first judgment operation is performed during this period, the second judgment operation is performed. In this example as well, once the first judgment operation is completed, the process moves to the second judgment operation, and it is determined that calibration is necessary.

[0141] The period from time t1 to time t2 in Figure 11C is the period during which the light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. During this period, the light intensity of the light-emitting element 202 is corrected, and the displacement signal decreases. On the other hand, since the biological signal is an amplified signal of the displacement signal, it is always at the upper limit during this period. In Processing Example 3, feedback control is performed to correct (reduce) the light intensity of the light-emitting element 202 while checking the value of the displacement signal one by one. At this time, the displacement signal changes more gradually compared to Processing Example 1 and Processing Example 2 in order to fine-tune the light intensity. Therefore, in the period from time t1 to time t2, the biological signal is larger than in the period from time t0 to time t1, but it does not rise to the upper limit.

[0142] The period from time t2 onwards in Figure 11C is the same as the period from time t4 onwards in Figure 11A. In other words, the first determination operation is performed, the second determination operation determines that calibration is unnecessary, and the calibration process ends. With this calibration method, calibration can be completed with a single light intensity correction.

[0143] Processing Example 4 will now be explained. In the following explanation, points similar to those in Processing Example 1 will be omitted, and the explanation will mainly focus on points specific to Processing Example 4. Figure 11D shows Processing Example 4 of calibration in which the displacement signal is corrected based on the light intensity setting value before the power is turned off. The period from time t02 to time t01 in Figure 11D is the period immediately before the user turns off the power to the electronic stethoscope 100, stopping all operations and turning off the power. In Processing Example 4, the electronic stethoscope 100 stores the value of the displacement signal at this time as value V01 [V], and the light intensity setting value of the light-emitting element 202 corresponding to value V01 as X01 [%]. The value V01 and the light intensity setting value X01 may be stored in a non-volatile memory provided in, for example, the calibration execution unit 520. In this example, the value V01 is equal to the target value Vt. At time t01, the power to the electronic stethoscope 100 is turned off, and the displacement signal becomes Lo level. The period from time t01 to time t0 in Figure 11D is the time of the electronic stethoscope 100. This is a period when the power source is off and no action is being taken.

[0144] Time t0 in Figure 11D represents the time when the electronic stethoscope 100 was turned on. The period from time t0 to time t1 in Figure 11D is the same as the period from time t0 to time t1 in Figure 11A. In other words, the first judgment operation is performed during this period, followed by the second judgment operation. In this example as well, once the first judgment operation is completed, the process moves to the second judgment operation, and it is determined that calibration is required.

[0145] The period from time t0 to time t1 in Figure 11D is the period during which the first and second judgment operations are executed again. In this example, during the period from time t0 to time t1, the displacement signal is a constant value greater than that of the period from time t02 to time t01, and is outside the second range (greater than the unsaturated line P3 (= second upper limit value TU2)). Therefore, once the first judgment operation is completed, the system proceeds to the second judgment operation again and determines that calibration is required. In processing example 4, the electronic stethoscope 100 stores the value of the displacement signal at this time as value V2 [V], and the light intensity setting value of the light-emitting element 202 corresponding to value V2 as X2 [%]. Note that the light intensity setting value X2 is equal to the light intensity setting value X01.

[0146] The period from time t1 to time t2 in Figure 11D is the period during which the light intensity correction, i.e., calibration, of S1005 in Figure 10 is performed. During this period, the light intensity of the light-emitting element 202 is corrected, and the displacement signal decreases. In processing example 4, the various values ​​stored earlier are used to bring the value of the displacement signal closer to the target value Vt.

[0147] In this example, X01 = X2, while V01 ≠ V2. Here, we assume that the displacement signal output from the photodetector 204 has ideal characteristics (for example, if the photodetector 204 is a phototransistor, the dark current can be ignored). In this case, the characteristics of the ideal light intensity adjustment value Xa [%] and the displacement signal Va [V] are given by a linear equation passing through zero. Xa = α * Va …(Equation 4) It can be expressed as follows: α is a coefficient. And the coefficient α after time t0 can be expressed as X2 / V2. Therefore, the target value Vt[V], which is the target value of the displacement signal, and the target light intensity setting value Xt[%] corresponding to the target value Vt are, Xt=(X2 / V2)*Vt…(Formula 5) This is the result. In this example, the target value Vt is set to the midpoint between the sensitivity guarantee line P2 and the unsaturation line P3. Then, the light intensity is corrected to the target light intensity setting value Xt calculated from the above formula through light intensity correction, and the displacement signal approaches the target value Vt. Also, the value of the biological signal at this time will be greater than the value during the period from time t0 to time t1.

[0148] The period from time t2 onwards in Figure 11D is the same as the period from time t4 onwards in Figure 11A. In other words, the first determination operation is performed, the second determination operation determines that calibration is unnecessary, and the calibration process ends. With this calibration method, calibration can be completed with a single light intensity correction.

[0149] Let's explain Processing Example 5. In the following explanation, we will omit explanations of points that are the same as in Processing Example 1, and mainly explain points specific to Processing Example 5. Figure 11E shows Processing Example 5, in which calibration is not performed correctly due to a timeout error. The period from time t0 to time t1 in Figure 11E is the same as the period from time t0 to time t1 in Figure 11A. Also, the period from time t1 to time t2 in Figure 11E is the same as the period from time t1 to time t2 in Figure 11A. In other words, in this example, we assume that the first light intensity correction was performed without any problems.

[0150] Time t3 in Figure 11E is the time when the diaphragm 206 begins to be pushed by an external force. After time t3, the biosignal is within the first range (first upper limit TU1 and first lower limit TL1). This includes the time during which the biological signal is outside the first range. In such cases, the first determination operation in S1003 of Figure 10 determines that the biological signal is outside the first range, and the process proceeds to S1006. In S1006, if the biological signal is outside the first range during time ts, time ts is added to the elapsed time during which the biological signal is outside the first range, and the elapsed time is accumulated. The counting of elapsed time begins when the first S1006 process starts.

[0151] In the first determination operation during the period from time t3 to time t4, the biological signal repeatedly falls outside the first range, and the processes S1003 and S1006 are repeated. In this example, in one first determination operation, if the biological signal is always within the first range during the period ts, the biological signal is determined to be within the first range; if it falls outside the range even once, the biological signal is determined to be outside the first range. After a total of seven first determination operations have been performed, S1006 determines that the cumulative elapsed time (7*ts) has exceeded a predetermined time. Then, at time t4, the timeout error processing in S1007 is started, and the calibration is stopped.

[0152] During the period from time t4 to time t5, as a timeout error handling process, the light intensity setting value is reset to the value before the calibration was performed, i.e., the value from time t0 to time t1. A timeout error occurs because the reliability of the light intensity correction performed before it is low, so the light intensity setting value is reset. In this example, the light intensity setting value is reset to the value from time t0 to time t1, but the configuration is not limited to this, and for example, it may be configured to reset to a pre-set initial value. Then, at time t5, the timeout error handling in S1007 is completed, the normal startup process in S1008 is started, and the calibration process is completed. During the period from time t5 onward, the electronic stethoscope 100 is started and becomes usable. With this calibration process flow, even if the calibration process fails, the electronic stethoscope 100 can be started and used.

[0153] <Second Embodiment> The electronic auscultation device 100 according to the second embodiment will now be described. The second embodiment differs from the first embodiment in the method for determining whether calibration can be performed. Hereinafter, only the differences between the configuration of the second embodiment and the configuration of the first embodiment will be described. Components in the second embodiment that are the same as those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0154] [Calibration process flow of the second embodiment] Referring to Figure 12, the calibration process flow in the electronic auscultation device 100 will be described. Figure 12 is a flowchart of the calibration process of the electronic auscultation device 100 of the second embodiment. Below, the differences between the calibration process flow of the second embodiment and that of the first embodiment shown in Figure 10 will be described in detail.

[0155] In the first embodiment, before performing calibration, a first determination operation in S1003 was performed to determine whether the diaphragm 206 was located within a predetermined range based on a biological signal. In the second embodiment, instead of the first determination operation in S1003 based on a biological signal, a first determination operation in S1203 based on a displacement signal is performed. In other words, the second embodiment is similar to the first embodiment in that it identifies the vibration state or pressure state of the diaphragm 206 based on the signal output by the photodetector 204 and determines whether the diaphragm 206 is in a state where calibration can be performed.

[0156] In S1203, as a first determination operation, the determination unit 530 determines whether or not the displacement signal is within a first range. The first determination operation is performed to determine whether the diaphragm 206 is located within a predetermined range and is in a state where calibration is possible. That is, the first determination operation determines whether the diaphragm 206 is being pushed or displaced based on the displacement signal. The first range (first upper limit TU1 and first lower limit TL1) used in the first determination operation is the die This is a predetermined range set to provide a buffer to the ideal value of the displacement signal when the displacement of the yafram 206 is zero. In the second embodiment, at least one of the first upper limit TU1 and the second upper limit TU2, and the first lower limit TL1 and the second lower limit TL2 are different values, and the first range and the second range are different predetermined ranges.

[0157] The first determination operation may, for example, determine that the displacement signal is not within the first range if the displacement signal falls outside the first range at least once during a predetermined period. However, the determination method is not limited to this, and for example, the difference between the maximum and minimum values ​​of the displacement signal during the predetermined period may be used, or count values ​​at predetermined intervals may be used instead of a predetermined period.

[0158] According to the configuration of the second embodiment, calibration can be performed when the diaphragm 206 is flat (or nearly flat) and not displaced by the first determination operation based on the displacement signal. Therefore, calibration can be performed with high accuracy, and a decrease in the detection accuracy of displacement and vibration of the biological surface 320 can be suppressed.

[0159] <Third Embodiment> The electronic auscultation device 100 according to the third embodiment will now be described. The third embodiment differs from the first embodiment in the method for determining whether calibration can be performed. Hereinafter, only the differences between the configuration of the third embodiment and the configuration of the first embodiment will be described. Components in the third embodiment that are the same as those in the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted.

[0160] [Hardware configuration of the electronic stethoscope in the third embodiment] Referring to Figure 13, an example of the hardware configuration of the electronic stethoscope 100 according to the third embodiment will be described. Figure 13 is a diagram showing an example of the hardware configuration of the electronic stethoscope 100 according to the third embodiment. The electronic stethoscope 100 has a pressure sensor 230 for detecting the pressure applied to the diaphragm 206.

[0161] The pressure sensor 230 is composed of, for example, a strain gauge formed inside the diaphragm 206. The pressure sensor 230 can detect the pressure applied to the diaphragm 206 based on the gauge resistance of the strain gauge, which changes in accordance with the displacement of the diaphragm 206. The detection result (detected pressure) of the pressure sensor 230 is used to determine whether or not calibration can be performed, as described later. In other words, the pressure sensor 230 can also be considered as one of the components of the determination unit 530.

[0162] [Calibration process flow of the third embodiment] Referring to Figure 14, the calibration process flow in the electronic auscultation device 100 will be described. Figure 14 is a flowchart of the calibration process of the electronic auscultation device 100 of the third embodiment. Below, the differences between the calibration process flow of the third embodiment and that of the first embodiment shown in Figure 10 will be described in detail.

[0163] In the third embodiment, the first determination operation based on the biological signal in S1003 is replaced by the first determination operation based on the detected pressure in S1303. In S1303, as the first determination operation, the determination unit 530 determines whether or not the detected pressure by the pressure sensor 230 is below a predetermined threshold. The first determination operation is performed to determine whether the diaphragm 206 is not being pressed and is in a state where calibration is possible. That is, the first determination operation identifies whether the diaphragm 206 is being pressed or displaced (vibration state or pressing state of the diaphragm 206) based on the detected pressure and determines whether or not calibration can be performed. The threshold used in the first determination operation is a predetermined value set to have a buffer over the ideal value (= zero) of the detected pressure when the displacement amount of the diaphragm 206 is zero.

[0164] The first determination operation may, for example, determine that the detected pressure is not below the threshold if the detected pressure exceeds the threshold at any point during a predetermined period. However, the determination method is not limited to this, and for example, the difference between the maximum and minimum values ​​of the detected pressure during the predetermined period may be used, or count values ​​at predetermined intervals may be used instead of a predetermined period.

[0165] According to the configuration of the third embodiment, calibration can be performed in a flat (or nearly flat) state where the diaphragm 206 is not displaced by the first determination operation based on the detected pressure. Therefore, calibration can be performed with high accuracy, and a decrease in the detection accuracy of displacement and vibration of the biological surface 320 can be suppressed. In the third embodiment, it was determined whether the diaphragm 206 was being pressed based on the detected pressure of the pressure sensor, but the determination method using the pressure sensor is not limited to this. For example, it may be determined whether the diaphragm 206 is being displaced (vibrating) based on the transition (change) of the detected pressure.

[0166] <Fourth Embodiment> The electronic auscultation device 100 according to the fourth embodiment will now be described. The fourth embodiment differs from the first embodiment in the method for determining whether calibration can be performed. Hereinafter, only the differences between the configuration of the fourth embodiment and the configuration of the first embodiment will be described. Components in the fourth embodiment that are the same as those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0167] [Hardware configuration of the electronic stethoscope in the fourth embodiment] Referring to Figure 15, an example of the hardware configuration of the electronic stethoscope 100 according to the fourth embodiment will be described. Figure 15 is a diagram showing an example of the hardware configuration of the electronic stethoscope 100 according to the fourth embodiment. The electronic stethoscope 100 has a distance sensor 240 that measures the distance to the diaphragm 206.

[0168] The distance sensor 240 is configured to measure the distance to the diaphragm 206. For example, a laser distance sensor using a laser can be used as the distance sensor 240. With a laser distance sensor, a laser is emitted toward the diaphragm 206, and the distance from the laser distance sensor to the diaphragm 206 can be detected using the reflected light of the laser. It is more preferable that the distance sensor 240 is configured to measure the distance between the center 206e of the diaphragm 206, where the displacement is most likely to be large, and the distance sensor 240. The measurement result of the distance sensor 240 (measured distance from the distance sensor 240 to the diaphragm 206) is used to determine whether or not calibration can be performed, as described later. In other words, the distance sensor 240 can also be considered as one of the components of the determination unit 530.

[0169] [Calibration process flow of the fourth embodiment] Referring to Figure 16, the calibration process flow in the electronic auscultation device 100 will be described. Figure 16 is a flowchart of the calibration process of the electronic auscultation device 100 of the fourth embodiment. Below, the differences between the calibration process flow of the fourth embodiment and that of the first embodiment shown in Figure 10 will be described in detail.

[0170] In the fourth embodiment, the first determination operation based on the biological signal in S1003 is replaced by the first determination operation based on the measured distance in S1403. In S1403, as the first determination operation, the determination unit 530 determines whether or not the measured distance by the distance sensor 240 is within a first range. The first determination operation is performed to determine whether the diaphragm 206 is located within a predetermined range and is in a state where calibration is possible. That is, the first determination operation identifies whether the diaphragm 206 is being pressed or displaced (vibration state or pressing state of the diaphragm 206) based on the measured distance and determines whether or not calibration can be performed. The first range used in the first determination operation (first upper limit TU1 and first lower limit TL1) is set to have a buffer over the ideal value of the measured distance when the displacement amount of the diaphragm 206 is zero. It is a defined range.

[0171] The first determination operation may, for example, determine that the measured distance is not within the first range if the measured distance falls outside the first range at any point during a predetermined period. However, the determination method is not limited to this, and for example, the difference between the maximum and minimum values ​​of the measured distance during the predetermined period may be used, or count values ​​at predetermined intervals may be used instead of a predetermined period.

[0172] According to the configuration of the fourth embodiment, calibration can be performed when the diaphragm 206 is flat (or nearly flat) and not displaced by a first determination operation based on the measured distance. Therefore, calibration can be performed with high accuracy, and a decrease in the detection accuracy of displacement and vibration of the biological surface 320 can be suppressed. Furthermore, in the fourth embodiment, the distance from the distance sensor 240 to the diaphragm 206 is measured, but the configuration is not limited to this. For example, a distance sensor capable of measuring the distance between the contact surface 206a, which is the outer surface of the diaphragm 206, and an object other than the electronic stethoscope 100 may be provided, and the configuration can be configured to determine that the diaphragm 206 is not displaced and calibration can be performed when there is no other object within a certain distance of the diaphragm 206. In other words, any distance sensor capable of measuring the distance from a predetermined object to the diaphragm 206 is sufficient, and the configuration is not limited to the above.

[0173] <Fifth Embodiment> The electronic auscultation device 100 according to the fifth embodiment will now be described. The fifth embodiment differs from the first embodiment in the method for determining whether calibration can be performed. Hereinafter, only the differences between the configuration of the fifth embodiment and the configuration of the first embodiment will be described. Components in the fifth embodiment that are the same as those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0174] [Hardware configuration of the electronic stethoscope in the fifth embodiment] Referring to Figure 17, an example of the hardware configuration of the electronic stethoscope 100 according to the fifth embodiment will be described. Figure 17 is a diagram showing an example of the hardware configuration of the electronic stethoscope 100 according to the fifth embodiment. The electronic stethoscope 100 has an illuminance sensor 250 that detects light from outside the diaphragm 206.

[0175] The illuminance sensor 250 is configured to detect light irradiated onto the diaphragm 206 from the outside. The detection result of the illuminance sensor 250 (illuminance of light from outside onto the diaphragm 206) is used to determine whether or not calibration can be performed, as described later. In other words, the illuminance sensor 250 can also be considered as one of the components of the determination unit 530.

[0176] [Calibration process flow of the fifth embodiment] Referring to Figure 18, the calibration process flow in the electronic auscultation device 100 will be described. Figure 18 is a flowchart of the calibration process of the electronic auscultation device 100 according to the fifth embodiment. Below, the differences between the calibration process flow of the fifth embodiment and that of the first embodiment shown in Figure 10 will be described in detail.

[0177] In the fifth embodiment, the first determination operation based on the detected illuminance in S1503 is performed instead of the first determination operation based on the biological signal in S1003. In S1503, as the first determination operation, the determination unit 530 determines whether or not the detected illuminance by the illuminance sensor 250 is within a first range. The first determination operation is performed to determine whether the diaphragm 206 is not being pressed and is in a state where calibration is possible. That is, the first determination operation determines whether the diaphragm 206 is being pressed or displaced based on the detected illuminance. Specifically, if the detected illuminance is below a predetermined threshold, it is determined that there may be another object blocking the light entering the diaphragm 206 and that the diaphragm 206 is being pressed by that other object. It is determined that the Yafram 206 is being pressed. In this configuration, it is preferable that the electronic stethoscope 100 is placed on a designated stand when calibration begins.

[0178] The first determination operation may, for example, determine that the detected illuminance is not below the threshold if the detected illuminance exceeds the threshold at least once during a predetermined period. However, the determination method is not limited to this, and for example, the difference between the maximum and minimum values ​​of the detected illuminance during the predetermined period may be used, or count values ​​at predetermined intervals may be used instead of a predetermined period.

[0179] According to the configuration of the fifth embodiment, calibration can be performed in a flat (or nearly flat) state where the diaphragm 206 is not displaced by the first determination operation based on the detected illuminance. Therefore, calibration can be performed with high accuracy, and a decrease in the detection accuracy of displacement and vibration of the biological surface 320 can be suppressed.

[0180] <Other Embodiments> The configurations shown in each of the embodiments described above can be combined as needed. The present invention can also be realized by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0181] This embodiment includes the following configuration. (Composition 1) A detection device for detecting vibrations of a target, A diaphragm having a reflective surface that moves in response to the vibration of the object to be detected, A light-emitting unit that emits light toward the reflective surface, A light receiving unit that receives light reflected by the reflective surface and outputs a signal corresponding to the light, A diaphragm unit that narrows the light emitted by the light-emitting unit before it reaches the light-receiving unit, Calibration execution means for performing at least one of the following as calibration: correction of the light intensity of the light-emitting part and correction of the light-receiving sensitivity of the light-receiving part. A determination means for determining whether or not the calibration can be performed according to the vibration state or pressing state of the diaphragm, A detection device characterized by comprising the following features. (Configuration 2) The detection device according to configuration 1, characterized in that the determination means identifies the vibration state or pressing state of the diaphragm based on the signal output by the light receiving unit and determines whether or not the calibration can be performed. (Composition 3) The system includes a signal processing unit that filters the signal output by the light receiving unit, The detection device according to configuration 1 or 2, characterized in that the determination means determines that the calibration is executable when the signal filtered by the signal processing unit is within a predetermined first range, and causes the calibration to be executed. (Composition 4) When the determination means determines that the calibration is performable, it determines whether the signal output by the light receiving unit is within a predetermined second range. The detection device according to configuration 3, characterized in that the calibration execution means performs the calibration when the determination means determines that the signal is within the predetermined second range. (Composition 5) The detection device according to configuration 1 or 2, characterized in that the determination means determines that the calibration is executable when the signal output by the light receiving unit is within a predetermined first range, and causes the calibration to be executed. (Composition 6) The determination means determines whether the signal output by the light receiving unit is within a predetermined second range that is different from the first range. The detection device according to configuration 5, characterized in that the calibration execution means performs the calibration when the determination means determines that the calibration is executable and the signal is within the predetermined second range. (Composition 7) The detection device according to configuration 3 or 4, characterized in that the calibration execution means discontinues the execution of the calibration if the determination means determines that the signal filtered by the signal processing unit is not within a predetermined first range for a predetermined period of time. (Composition 8) The detection device according to configuration 7, further comprising a notification means for notifying the user of the discontinuation of calibration when the calibration execution means discontinues the execution of the calibration. (Composition 9) The light-emitting section includes an emitter follower constant current circuit. The detection device according to any one of configurations 1 to 8, characterized in that the calibration execution means corrects the light intensity of the light-emitting part by adjusting the duty cycle of the PWM signal received by the constant current circuit. (Composition 10) The light-emitting section includes a constant current circuit of an emitter follower having a resistor with a switchable resistance value. The detection device according to any one of configurations 1 to 8, characterized in that the calibration execution means corrects the light intensity of the light-emitting part by switching the resistance value of the resistor. (Composition 11) The light-receiving unit includes a light-receiving element and a circuit for converting the output current of the light-receiving element into current / voltage, the circuit having a resistor. The detection device according to any one of configurations 1 to 8, characterized in that the calibration execution means corrects the light receiving sensitivity of the light receiving unit by correcting the resistance value of the resistor using the circuit. (Composition 12) The light-receiving unit includes a light-receiving element, a power supply for the light-receiving element, and a circuit for correcting the voltage of the power supply. The detection device according to any one of configurations 1 to 8, characterized in that the calibration execution means corrects the light receiving sensitivity of the light receiving unit by correcting the voltage of the power supply of the light receiving element using the circuit. (Composition 13) The light-receiving unit includes a light-receiving element and a power supply that supplies power to the light-receiving element. The detection device according to any one of configurations 1 to 8, characterized in that the calibration execution means performs the calibration by adjusting the voltage of the power supply. (Composition 14) The detection device according to any one of configurations 1 to 13, characterized in that the signal output by the light receiving unit is the area of ​​the light-irradiated region formed by specularly reflected light reaching the light receiving unit, and changes according to the area of ​​the light-irradiated region which changes according to the displacement of the reflective surface of the diaphragm. (Composition 15) The detection device according to configuration 1, wherein the determination means includes a pressure sensor for detecting the pressure applied to the diaphragm, and the detection means identifies the vibration state or pressing state of the diaphragm based on the detection result of the pressure sensor and determines whether or not the calibration can be performed. (Composition 16) The detection device according to configuration 1, wherein the determination means includes a distance sensor that measures the distance from a predetermined object to the diaphragm, and the detection device determines whether or not the vibration state or pressing state of the diaphragm is determined based on the distance measured by the distance sensor, and whether or not the calibration can be performed. (Composition 17) The detection device according to configuration 1, wherein the determination means includes an illuminance sensor that measures the illuminance of light received by the diaphragm from the outside, and the detection means identifies the vibration state or pressing state of the diaphragm based on the detection result of the illuminance sensor and determines whether or not the calibration can be performed. (Composition 18) The light-emitting part is a light-emitting diode, The aperture portion restricts the light emitted from the light-emitting diode. The detection device according to any one of configurations 1 to 17, characterized in that the light receiving unit receives light that has passed through the aperture unit and been reflected by the reflective surface. (Composition 19) A detection device as described in any one of items 1 to 18, A sound output unit that outputs a signal to a sound output device to emit sound based on the signal generated by the detection device, An electronic stethoscope characterized by being equipped with the following features. (Composition 20) The electronic auscultation device according to configuration 19, characterized in that the determination means identifies the vibration state or pressing state of the diaphragm based on the signal output by the sound output unit and determines whether or not the calibration can be performed. (Composition 21) The electronic auscultation device according to configuration 19 or 20, characterized in that the sound output unit includes a filter for filtering the signal output by the light receiving unit and an amplifier for amplifying the signal. [Explanation of symbols]

[0182] 100...Electronic stethoscope, 110...Chestpiece, 206...Diaphragm, 209...Constrictor, 210...Constrictor

Claims

1. A detection device for detecting vibrations of a target, A diaphragm having a reflective surface that moves in response to the vibration of the object to be detected, A light-emitting unit that emits light toward the reflective surface, A light receiving unit that receives light reflected by the reflective surface and outputs a signal corresponding to the light, A diaphragm unit that narrows the light emitted by the light-emitting unit before it reaches the light-receiving unit, Calibration execution means for performing at least one of the following as calibration: correction of the light intensity of the light-emitting part and correction of the light-receiving sensitivity of the light-receiving part. A determination means for determining whether or not the calibration can be performed according to the vibration state or pressing state of the diaphragm, A detection device characterized by comprising the following features.

2. The detection device according to claim 1, characterized in that the determination means identifies the vibration state or pressing state of the diaphragm based on the signal output by the light receiving unit and determines whether or not the calibration can be performed.

3. The system includes a signal processing unit that filters the signal output by the light receiving unit, The detection device according to claim 1, characterized in that the determination means determines that the calibration is executable and executes the calibration when the signal filtered by the signal processing unit is within a predetermined first range.

4. When the determination means determines that the calibration is performable, it determines whether the signal output by the light receiving unit is within a predetermined second range. The detection device according to claim 3, characterized in that the calibration execution means performs the calibration when the determination means determines that the signal is within the predetermined second range.

5. The detection device according to claim 1, characterized in that the determination means determines that the calibration is executable when the signal output by the light receiving unit is within a predetermined first range, and causes the calibration to be executed.

6. The determination means determines whether the signal output by the light receiving unit is within a predetermined second range that is different from the first range. The detection device according to claim 5, wherein the calibration execution means performs the calibration when the determination means determines that the calibration is executable and the signal is within the predetermined second range.

7. The detection device according to claim 3, characterized in that the calibration execution means discontinues the execution of the calibration if the determination means determines that the signal filtered by the signal processing unit is not within a predetermined first range after a predetermined time.

8. The detection device according to claim 7, further comprising notification means for notifying the user of the discontinuation of calibration when the calibration execution means discontinues the execution of the calibration.

9. The light-emitting section includes an emitter follower constant current circuit. The detection device according to claim 1, characterized in that the calibration execution means corrects the light intensity of the light-emitting part by adjusting the duty cycle of the PWM signal received by the constant current circuit.

10. The light-emitting section includes a constant current circuit of an emitter follower having a resistor with a switchable resistance value. The detection device according to claim 1, characterized in that the calibration execution means corrects the amount of light emitted by the light-emitting part by switching the resistance value of the resistor.

11. The light-receiving unit includes a light-receiving element and a circuit for converting the output current of the light-receiving element into current / voltage, the circuit having a resistor. The detection device according to claim 1, characterized in that the calibration execution means corrects the light receiving sensitivity of the light receiving unit by correcting the resistance value of the resistor using the circuit.

12. The light-receiving unit includes a light-receiving element, a power supply for the light-receiving element, and a circuit for correcting the voltage of the power supply. The detection device according to claim 1, characterized in that the calibration execution means corrects the light receiving sensitivity of the light receiving unit by correcting the voltage of the power supply of the light receiving element using the circuit.

13. The light-receiving unit includes a light-receiving element and a power supply that supplies power to the light-receiving element. The detection device according to claim 1, characterized in that the calibration execution means performs the calibration by adjusting the voltage of the power supply.

14. The detection device according to claim 1, wherein the signal output by the light receiving unit is the area of ​​the light-irradiated region formed by specularly reflected light reaching the light receiving unit, and changes in accordance with the area of ​​the light-irradiated region which changes in accordance with the displacement of the reflective surface of the diaphragm.

15. The detection device according to claim 1, wherein the determination means includes a pressure sensor for detecting the pressure applied to the diaphragm, and determines whether the vibration state or pressing state of the diaphragm can be identified based on the detection result of the pressure sensor, and whether the calibration can be performed.

16. The detection device according to claim 1, wherein the determination means includes a distance sensor for measuring the distance from a predetermined object to the diaphragm, and determines whether the vibration state or pressing state of the diaphragm is determined based on the distance measured by the distance sensor, and whether the calibration can be performed.

17. The detection device according to claim 1, wherein the determination means includes an illuminance sensor that measures the illuminance of light received by the diaphragm from the outside, and determines whether the vibration state or pressing state of the diaphragm is determined based on the detection result of the illuminance sensor, and whether or not the calibration can be performed.

18. The light-emitting part is a light-emitting diode, The aperture portion restricts the light emitted from the light-emitting diode. The detection device according to claim 1, characterized in that the light receiving unit receives light that has passed through the aperture unit and been reflected by the reflective surface.

19. A detection device according to any one of claims 1 to 18, A sound output unit that outputs a signal to a sound output device to emit sound based on the signal generated by the detection device, An electronic stethoscope characterized by being equipped with the following features.

20. The electronic auscultation device according to claim 19, characterized in that the determination means identifies the vibration state or pressing state of the diaphragm based on the signal output by the sound output unit and determines whether or not the calibration can be performed.

21. The electronic auscultation device according to claim 19, characterized in that the sound output unit includes a filter for filtering the signal output by the light receiving unit and an amplifier for amplifying the signal.

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