Electronic auscultation device

Abstract

This electronic auscultation device comprises: an output means for outputting a biological sound signal representing a biological sound based on vibrations of a biological surface; a detection means for detecting the state of movement of the electronic auscultation device; and an adjustment means for adjusting the level of the biological sound signal with a gain set on the basis of the state of movement of the electronic auscultation device detected by the detection means. The adjustment means sets the gain to a first gain if the state of movement is a first state, sets the gain to a second gain higher than the first gain if the state of movement is a second state in which the stability of the movement is higher than that in the first state, and sets the gain to a third gain lower than the second gain if the state of movement is a third state in which the stability of the movement is higher than that in the second state.

Description

Electronic stethoscope

[0001] The present disclosure relates to electronic auscultation devices.

[0002] Electronic auscultation devices for acquiring body sounds based on vibrations on the body surface are becoming popular. Electronic auscultation devices have a vibration detection unit that detects vibrations on the body surface and generates a body sound signal that indicates the detection result. Electronic auscultation devices are configured so that the level of the body sound signal can be adjusted using an amplifier or the like to make it easier for the auscultator to hear the body sounds.

[0003] The vibration detection unit of an electronic auscultation device can also detect vibrations unrelated to vibrations on the body surface. For example, the vibration detection unit can detect vibrations unrelated to vibrations on the body surface when in contact with the subject. Furthermore, the vibration detection unit can detect airborne vibrations caused by conversation between the auscultator and the subject or environmental sounds. In such cases, the body sound signal output from the vibration detection unit is a signal indicating noise unrelated to body sounds. Generally, the vibrations detected by the vibration detection unit when the vibration detection unit is in contact with the subject are larger than those caused by vibrations on the body surface. Therefore, the sound output from the electronic auscultation device when the vibration detection unit is in contact with the subject (hereinafter referred to as output sound) can be at a level that is uncomfortable for the auscultator. Furthermore, although the vibrations detected by the vibration detection unit due to conversation or environmental sounds are relatively small, if the gain of the amplifier of the electronic auscultation device is high, the output sound can be at a level that is uncomfortable for the auscultator.

[0004] For this reason, Patent Document 1 discloses a configuration in which the output sound level is reduced for a certain period of time after the electronic auscultation device is brought into contact with the subject. Also, Patent Document 2 discloses a configuration in which the output of the electronic auscultation device is muted until the electronic auscultation device is brought into contact with the subject, the muting is released a predetermined period of time after the electronic auscultation device is brought into contact with the subject, and the output of the electronic auscultation device is muted again after a certain period of time has passed since the muting was released.

[0005] JP2020-78642A JP10-24033A

[0006] In the configuration of Patent Document 1, output sounds based on conversation sounds and environmental sounds before the electronic auscultation device is brought into contact with the subject are output from the electronic auscultation device, which can be unpleasant for the auscultator. In the configuration of Patent Document 2, the output of the electronic auscultation device is muted after a given time has elapsed since muting is released, which can lead to the mute state being entered during auscultation depending on the time setting. Furthermore, depending on the time setting, the unmuted state may remain even after auscultation has ended, resulting in the output sounds based on conversation sounds and environmental sounds being output from the electronic auscultation device, which can be unpleasant for the auscultator.

[0007] According to one aspect of the present disclosure, an electronic auscultation device comprises an output means for outputting a biological sound signal indicating biological sounds based on vibrations of the surface of a living body, a detection means for detecting the movement state of the electronic auscultation device, and an adjustment means for adjusting the level of the biological sound signal with a gain set based on the movement state of the electronic auscultation device detected by the detection means, wherein the adjustment means sets the gain to a first gain when the movement state is a first state, sets the gain to a second gain larger than the first gain when the movement state is a second state having higher movement stability than the first state, and sets the gain to a third gain smaller than the second gain when the movement state is a third state having higher movement stability than the second state.

[0008] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0009] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0014] Figure 1 shows an example of the appearance of an electronic auscultation device, according to some embodiments.

[0015] Another view showing an example of the appearance of an electronic auscultation device, according to some embodiments.

[0016] Figure 2 shows an example of the configuration of a chestpiece, according to some embodiments.

[0017] Block diagram showing an example of the configuration of an electronic auscultation device, according to one embodiment.

[0018] Flowchart of a gain determination process, according to one embodiment.

[0019] Figure 3 shows an example of the configuration of a chestpiece, according to some embodiments.

[0020] Figure 4 shows an example of the configuration of an electronic auscultation device, according to one embodiment.

[0021] Flowchart of a gain determination process, according to one embodiment.

[0022] Figure 5 shows an example of the configuration of an electronic auscultation device, according to one embodiment.

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0011] In addition, in the following drawings, a coordinate system CS, which is a three-dimensional Cartesian coordinate system having an x-axis, a y-axis, and a z-axis, is shown as necessary.

[0012] 1A and 1B show a schematic external view of an electronic auscultation device 100. The electronic auscultation device 100 includes a chestpiece 110 and a grip portion 120. The chestpiece 110 is the part that comes into contact with a living body during diagnosis using the electronic auscultation device 100. The chestpiece 110 detects displacement of the living body surface via a diaphragm, and is therefore also called a displacement detection device or a diaphragm displacement detection device. The chestpiece 110 can also be called a living body vibration detection device because it detects vibrations on the living body surface.

[0013] The chestpiece 110 is attached to one end of the grip 120 (negative side of the x-axis in FIG. 1 ). The grip 120 is the part that is gripped when a user of the electronic auscultation device 100 (e.g., a doctor, nurse, or public health nurse) presses the diaphragm of the chestpiece 110 against the surface of a living body. Hereinafter, the "user of the electronic auscultation device 100" will be referred to simply as the "user." The grip 120 may also be called a handle, a grip, a handle, or the like.

[0014] The grip part 120 has a battery and a circuit board inside a housing 121. The battery stores operating power for the electronic auscultation device 100. The circuit board has circuit elements for controlling the operation of the electronic auscultation device 100. The grip part 120 has a display unit 122, an operation unit 123, a power switch 124, and a connector 125 on the outer surface of the housing 121.

[0015] The display unit 122 displays the status of the electronic auscultation device 100. For example, the display unit 122 may include multiple indicators (four indicators in the example of FIG. 1A ). Each indicator may be configured with a light-emitting diode (LED). The multiple indicators may include an indicator indicating whether the power of the electronic auscultation device 100 is on or off. The multiple indicators may include an indicator indicating the current operating mode of the electronic auscultation device 100. The multiple indicators may include an indicator indicating whether the electronic auscultation device 100 is wirelessly connected to an external device. The multiple indicators may include an indicator indicating whether the chestpiece 110 is pressed against a living body surface. Instead of or in addition to the multiple indicators, the display unit 122 may display the status of the electronic auscultation device 100 using a liquid crystal panel or an electrostatic panel.

[0016] The operation unit 123 accepts operations from the user. The operation unit 123 may include, for example, multiple physical buttons. In the example of FIG. 1 , the operation unit 123 has adjustment buttons (up button 123a and down button 123b) for adjusting the level of the output sound and a mode switching button 123c for switching the operation mode of the electronic auscultation device 100. The operation unit 123 may include a touch panel instead of multiple physical buttons. Furthermore, the display unit 122 and the operation unit 123 may be integrated into a touch screen.

[0017] The power switch 124 is a switch that switches the power of the electronic auscultation device 100 on and off. The connector 125 is a connector for receiving a cable or a connector of an external device. Power is supplied from the external device to the battery of the grip portion 120 through the connector 125. The power switch 124 may be provided on the chestpiece 110 instead of the grip portion 120. The connector 125 may be provided on the chestpiece 110 instead of the grip portion 120. Furthermore, the electronic auscultation device 100 may not include the connector 125. In this case, the electronic auscultation device 100 may have a wireless charging function or may be configured so that the battery is replaceable.

[0018] Fig. 2 shows the configuration of the chestpiece 110. The upper side of Fig. 2 is a cross-sectional view of the chestpiece 110, and the lower side of Fig. 2 is a plan view of the chestpiece 110. Note that in the plan view of Fig. 2, only the light-emitting circuit board 203, the light-receiving circuit board 205, the diaphragm 206, and the reflecting member 207 are shown in order to clarify the positional relationship of the components.

[0019] The light-emitting element 202 is a light source that emits light. In this embodiment, the light-emitting element 202 is a light-emitting diode (LED), but other light-emitting elements such as a laser diode (LD) can also be used as the light-emitting element 202. The light-emitting element 202 is mounted on a light-emitting circuit board 203. For example, peripheral circuits for controlling the light emission of the light-emitting element 202 are mounted on the light-emitting circuit board 203. The light-emitting circuit board 203 including the light-emitting element 202 functions as a light-emitting unit.

[0020] The light receiving element 204 receives light and generates an electrical signal based on the amount of received light. The light receiving element 204 may be, for example, a phototransistor or a complementary metal-oxide semiconductor (CMOS) sensor. In this embodiment, the number of light receiving elements 204 is one, but a configuration using multiple light receiving elements 204 is also possible. The light receiving element 204 is mounted on a light receiving circuit board 205. Peripheral circuits and the like are mounted on the light receiving circuit board 205 for reading out signals from the light receiving element 204 and outputting electrical signals. The light receiving circuit board 205 including the light receiving element 204 functions as a light receiving unit.

[0021] The holding member 201 holds a light-emitting circuit board 203 and a 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. The holding member 201 also holds a diaphragm 206. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 is a membrane having a circular outer edge in a plan view. The diaphragm 206 is arranged to contact a biological surface. The diaphragm 206 constitutes a part of the outer surface of the chestpiece 110. The diaphragm 206 has an outer surface 206a arranged to contact a biological surface when the electronic auscultation device 100 is in use, and an inner surface 206b opposite the outer surface 206a.

[0022] 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 periphery of the diaphragm 206. The inner periphery of the diaphragm 206 (i.e., the portion inside the fixed portion 206c) is not fixed to the holding member 201. Therefore, the diaphragm 206 can vibrate in the z-axis direction with the fixed portion 206c as a node. Specifically, when the chestpiece 110 is in use, the diaphragm 206 vibrates with the fixed portion 206c as a node in response to vibrations on the surface of the living body. In this vibration, the center 206e of the diaphragm 206 becomes an antinode. The diaphragm 206 functions as a vibrating unit.

[0023] The reflecting member 207 is a reflecting portion that reflects light emitted from the light-emitting element 202. The reflecting member 207 is adhered to the inner surface 206b of the diaphragm 206, and therefore vibrates in the z-axis direction in conjunction with the vibration of the diaphragm 206, which is in close contact with the surface of the living body. The reflecting member 207 has a circular outer edge in a plan view. The outer edge of the reflecting member 207 may have other shapes. The reflecting member 207 is positioned to cover a region 206d including the center 206e of the diaphragm 206. Since the displacement of the diaphragm 206 changes most significantly at the center 206e, the vibration 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 reflecting member 207 is positioned to cover the center 206e. However, the reflecting member 207 may also be positioned to cover a region of the diaphragm 206 that does not include the center 206e. The reflecting member 207 is formed, for example, of an aluminum-deposited film.

[0024] The light-emitting element 202 emits light toward the reflecting member 207, and the upper surface of the reflecting member 207 reflects the light emitted by the light-emitting element 202. That is, the upper surface of the reflecting member 207 functions as a light-reflecting surface. In the following description, the reflection of light on the upper surface (i.e., the light-reflecting surface) of the reflecting member 207 will simply be referred to as light being reflected by the reflecting member 207. The reflecting member 207 specularly reflects (in other words, specularly reflects) the light emitted by the light-emitting element 202. In the following description, as shown in FIG. 2B , the light traveling from the light-emitting element 202 toward the reflecting member 207 will be referred to as incident light 211, and the light after the incident light 211 is reflected will be referred to as reflected light 212.

[0025] In this embodiment, the reflecting member 207 is a separate member from the diaphragm 206. However, the reflecting member 207 may be a coating layer applied to the diaphragm 206. The reflecting member 207 may also be a sticker or the like attached to the diaphragm 206. The reflecting member 207 may be formed as the same member as the diaphragm 206, and at least a portion of the inner surface 206b of the diaphragm 206 may also serve as a reflecting portion. For example, the entire inner surface 206b of the diaphragm 206 may have a high reflectivity that can reflect light to an extent that can be detected by the light receiving element 204. Alternatively, only a region of the inner surface 206b of the diaphragm 206 that is reached by light irradiated by the light emitting element 202 may have such a high reflectivity.

[0026] When the diaphragm 206 is not in contact with the surface of the living body, the light emitting element 202 can be arranged to irradiate a region 207a of the reflecting member 207 that includes a portion covering the center 206e of the diaphragm 206. When the diaphragm 206 is not in contact with the surface of the living body, the diaphragm 206 is flat.

[0027] In this embodiment, as described above, an LED that emits diffused light is used as the light-emitting element 202. Therefore, the chestpiece 110 has an aperture 209 that limits the range of light emitted from the light-emitting element 202. The aperture 209 ensures that only a portion of the light emitted by the light-emitting element 202 is irradiated onto the reflecting member 207. In the example of FIG. 2 , an opening formed in the holding member 201 corresponds to the aperture 209. Note that, in this embodiment, a component that emits diffused light has been described as an example of the light-emitting element 202. However, instead, a component that emits linear light may be used as the light-emitting element 202, and the linear light may be irradiated toward the region 207 a. Note that the aperture 209 may also be used when the light-emitting element 202 is a component that emits linear light.

[0028] The light receiving element 204 is disposed so as to receive the reflected light 212. Specifically, the light receiving element 204 is disposed at a position where the amount of received reflected light 212 changes due to vibration of the diaphragm 206 in the z-axis direction. The light receiving element 204 is disposed so as to receive more light of the reflected light 212 when the diaphragm 206 is not in contact with the surface of the living body (i.e., when the diaphragm 206 is flat) than when the diaphragm 206 is vibrating. Therefore, the light receiving element 204 outputs an electrical signal corresponding to the vibration of the diaphragm 206. The electrical signal output by the light receiving element 204 is output via a peripheral circuit mounted on the light receiving circuit board 205.

[0029] The chestpiece 110 has an aperture 210 that limits the range of light that enters the light receiving element 204. The aperture 210 prevents diffusely reflected light from entering the light receiving element 204 and allows only at least a portion of the light from the reflecting member 207 (i.e., the primarily reflected light) to reach the light receiving element 204. In the example of Fig. 2, an opening formed in the holding member 201 functions as the aperture 210. Alternatively, the aperture 210 may be formed in a different manner.

[0030] A housing 208 is attached to the outer circumferential upper surface of the holding member 201. The housing 208 covers the light-emitting circuit board 203 and the light-receiving circuit board 205 and prevents ambient sound from entering the housing 208. The outer edges of the diaphragm 206, the holding member 201, and the housing 208 may coincide with one another in a plan view with respect to the outer surface 206a of the diaphragm 206. In this embodiment, the housing 208 is made of stainless steel.

[0031] By fixing the diaphragm 206 to the holding member 201, an internal space surrounded by the diaphragm 206 and the holding member 201 is formed. The internal space is sealed in order to prevent light different from the light reflected by the light emitting element 202 from entering the light receiving element 204. Furthermore, the diaphragm 206 has light-blocking properties in order to prevent light different from the light reflected by the light emitting element 202 from entering the light receiving element 204. Alternatively or in addition to this, the diaphragm 206 may be covered with a light-blocking film. Similarly, the holding member 201 may have light-blocking properties or may be covered with a light-blocking film.

[0032] In this embodiment, a status detection sensor 300 is attached to the holding member 201. The status detection sensor 300 may be attached to the inner surface of the housing 208 instead of the holding member 201. The status detection sensor 300 is a sensor that detects the movement of the chestpiece 110. If the grip portion 120 moves integrally with the chestpiece 110, the status detection sensor 300 may be provided on the grip portion 120. In other words, if the overall movement of the electronic auscultation device 100 is similar to the movement of the chestpiece 110, the status detection sensor 300 only needs to detect the movement of the electronic auscultation device 100. The status detection sensor 300 may have, as a detection element, an acceleration sensor that detects acceleration as a detected value of the movement of the chestpiece 110. Alternatively, the status detection sensor 300 may have, as a detection element, an angular velocity sensor (gyro sensor) that detects angular velocity as a detected value of the movement of the chestpiece 110. The status detection sensor 300 outputs a detection value at each sampling period.

[0033] In the following description, it is assumed that the status detection sensor 300 has a triaxial acceleration sensor as a detection element. Furthermore, it is assumed that the axial directions of the triaxial acceleration sensor coincide with the x-, y-, and z-axis directions of the coordinate system CS shown in the figure. Therefore, the detected values ​​output by the status detection sensor 300 at each sampling period are accelerations in the x-, y-, and z-axis directions. As will be clear from the following description, the axial directions of the acceleration sensor do not have to coincide with the x-, y-, and z-axis directions.

[0034] In the following description, the components of the chestpiece 110 for outputting an electrical signal corresponding to the vibration of the diaphragm 206, i.e., the light-emitting element 202, the light-emitting circuit board 203, the light-receiving element 204, the light-receiving circuit board 205, and the reflecting member 207, are referred to as the vibration detection unit 200 (see FIG. 3 ). Furthermore, the electrical signal corresponding to the vibration of the diaphragm 206 output by the vibration detection unit 200 is referred to as a body sound signal. The vibration detection unit 200 can also be referred to as a body sound signal output unit that outputs a body sound signal.

[0035] 3 is a block diagram of the electronic auscultation device 100 according to this embodiment. The biological sound signal output by the vibration detection unit 200 is input to the adjustment unit 402 of the grip unit 120. The detection value (detection result) detected by the state detection sensor 300 is input to the gain setting unit 403 of the grip unit 120. In this embodiment, the detection value output by the state detection sensor 300 is the acceleration in each of the x-axis, y-axis, and z-axis directions. The storage unit 404 of the grip unit 120 stores two thresholds in advance: a first threshold and a second threshold smaller than the first threshold.

[0036] The gain setting unit 403 determines a gain based on the detection value from the state detection sensor 300 and the first and second thresholds stored in the storage unit 404, and notifies the adjustment unit 402 of the determined gain by a gain setting signal. Details of the gain determination method will be described later. The gain setting unit 403 may be configured as hardware using an application specific integrated circuit (ASIC) or the like. Alternatively, the gain setting unit 403 may be realized as software by causing one or more processors to execute an appropriate program. Alternatively, the gain setting unit 403 may be realized as a combination of hardware and software.

[0037] The level setting unit 401 notifies the adjustment unit 402 of the reference level set by the user by operating the adjustment buttons (up button 123a and down button 123b) of the operation unit 123 via a level setting signal. The adjustment unit 402 has, for example, an amplifier. The adjustment unit 402 determines the adjusted level of the body sound signal based on the reference level indicated by the level setting signal and the gain indicated by the gain setting signal, and outputs the level-adjusted body sound signal as an output signal. In this embodiment, the level of the output signal (the level of the adjusted body sound signal) is R×g, where R is the reference level indicated by the level setting signal and g is the gain indicated by the gain setting signal. In this embodiment, the gain g is a value between 0 and 1.

[0038] The output unit 405 outputs an output signal to the outside. As an example, the output unit 405 is a jack for connecting earphones or headphones. The output unit 405 outputs the output signal to the earphones or headphones via the jack. The earphones or headphones output sound corresponding to the output signal. As another example, the output unit 405 is a wireless transmitter that wirelessly transmits data for reproducing the sound indicated by the output signal. For example, the output unit 405 generates data from the output signal and outputs the generated data to wireless earphones or wireless headphones. The wireless earphones or wireless headphones output sound corresponding to the output signal based on the data. As another example, the output unit 405 generates data from the output signal and transmits the generated data to a personal computer or a portable information processing device such as a smartphone or tablet. The personal computer or portable information processing device outputs sound corresponding to the output signal based on the data, or stores the data in a memory device for later playback.

[0039] A method for determining the gain in the gain setting unit 403 will be described below. The gain setting unit 403 calculates an evaluation value for evaluating the state of movement of the electronic auscultation device 100, more specifically, the chestpiece 110 (hereinafter referred to as the "movement state"), based on detection values ​​from the vibration detection unit 200 over a predetermined past period. The evaluation value may be a value corresponding to the instability (or stability) of the movement of the chestpiece 110. The evaluation value may also be a value corresponding to the instability (or stability) of the posture of the chestpiece 110. As an example, the evaluation value may be a value that increases as the movement or posture of the chestpiece 110 becomes more unstable.

[0040] In this embodiment, the evaluation value is the variance of multiple detection values ​​over a predetermined period of time. The variance is an example of a value that indicates the variation in the multiple detection values. Note that other values ​​that indicate the variation in the multiple detection values ​​or values ​​based on the variance can also be used as the evaluation value. A large variation in the multiple detection values, for example, a large variance, indicates that the chestpiece 110 is moving unstably (has an unstable posture). On the other hand, a small variation in the multiple detection values, for example, a small variance, indicates that the chestpiece 110 is moving steadily (has a stable posture). For example, if the chestpiece 110 is left stationary on a desk, the evaluation value will be approximately 0.

[0041] In this way, in the following description, the evaluation value is set to a value that increases as the movement of the chestpiece 110 becomes unstable, but the evaluation value may also be set to a value that decreases as the movement of the chestpiece 110 becomes unstable. The predetermined past period used to determine the evaluation value and the sampling period of the state detection sensor 300 are determined so as to obtain the evaluation value necessary to classify the movement state of the electronic auscultation device 100. As an example, the sampling period is set to 10 ms, and the evaluation value can be determined based on 50 detection values ​​over a period of 500 ms.

[0042] In this embodiment, the detected values ​​indicate the acceleration in each of the x-axis, y-axis, and z-axis directions, and therefore the variance values ​​used as the evaluation value are also calculated for each of the x-axis, y-axis, and z-axis directions. In other words, in this embodiment, the evaluation value is a collective term for the variance values ​​of the acceleration in each of the x-axis, y-axis, and z-axis directions.

[0043] The gain setting unit 403 compares the evaluation value with a first threshold and a second threshold stored in the storage unit 404, and classifies the movement state of the chestpiece 110 into three states: a first state, a second state, and a third state. Specifically, if the evaluation value is greater than the first threshold, the gain setting unit 403 determines the movement state of the chestpiece 110 to be the first state. If the evaluation value is equal to or less than the first threshold and greater than the second threshold, the gain setting unit 403 determines the movement state of the chestpiece 110 to be the second state. If the evaluation value is equal to or less than the second threshold, the gain setting unit 403 determines the movement state of the chestpiece 110 to be the third state.

[0044] Alternatively, the gain setting unit 402 may be configured to determine the first state when the evaluation value is equal to or greater than the first threshold, the second state when the evaluation value is less than the first threshold and equal to or greater than the second threshold, and the third state when the evaluation value is less than the second threshold. In other words, when the evaluation value is equal to a threshold, it is optional whether to determine the state as greater than the threshold or as less than the threshold. Therefore, more generally, the gain setting unit 402 determines the first state when the evaluation value is within the first range, the second state when the evaluation value is within the second range, and the third state when the evaluation value is within the third range. Here, values ​​within the first range are greater than values ​​within the second range, and values ​​within the second range are greater than values ​​within the third range. Furthermore, values ​​included in all ranges from the first range to the third range encompass the ranges that the evaluation value can take.

[0045] In this embodiment, the evaluation value includes variance values ​​in the x-axis, y-axis, and z-axis directions, and "the evaluation value is greater than the threshold" means that at least one of the three variance values ​​is greater than the threshold. Conversely, "the evaluation value is smaller than the threshold" means that all of the three variance values ​​are smaller than the threshold. Furthermore, "the evaluation value is greater than or equal to the threshold" means that at least one of the three variance values ​​is greater than the threshold, and "the evaluation value is less than or equal to the threshold" means that all of the three variance values ​​are less than the threshold.

[0046] The first state is a state in which the electronic auscultation device 100 is moving unstably, for example, when the user is manually moving the electronic auscultation device 100 toward the subject for auscultation. In the following description, the first state is also referred to as the "unstable non-auscultation state." The third state is a state in which the electronic auscultation device 100 is moving stably (including a stationary state), for example, when the electronic auscultation device 100 is left on a desk. In the following description, the third state is also referred to as the "stable non-auscultation state." Furthermore, in the following description, the unstable non-auscultation state and the stable non-auscultation state are collectively referred to as the "non-auscultation state." The second state is a state in which the electronic auscultation device 100 is moving with a moderate degree of instability, and corresponds to a state in which the user is performing auscultation using the electronic auscultation device 100. In the following description, the second state is also referred to as the "auscultation state."

[0047] The first threshold and the second threshold are determined, for example, experimentally, so as to accurately determine whether or not auscultation is being performed with the electronic auscultation device 100, that is, whether or not the device is in an auscultating state.

[0048] When the gain setting unit 403 determines that the movement state of the electronic auscultation device 100 is an unstable non-auscultation state, it sets the target gain to G1. When the gain setting unit 403 determines that the movement state of the electronic auscultation device 100 is an auscultation state, it sets the target gain to G2. When the gain setting unit 403 determines that the movement state of the electronic auscultation device 100 is a stable non-auscultation state, it sets the target gain to G3. Here, the target gains G1 and G3 are smaller than the target gain G2. The target gains G1 and G3 may be the same value or different values. Hereinafter, for simplicity of explanation, unless it is clearly stated that the target gains G1 and G3 are different values, the target gains G1 and G3 will be considered to be the same value. Furthermore, the target gain in the third state will be referred to as the target gain G1 rather than the target gain G3.

[0049] The target gain G2 is set to 1 or a value close to 1 so as to minimize the difference between the output signal level and the reference level. On the other hand, the target gains G1 and G3 can be set to 0 or a value close to 0, such as 0.1, so as not to cause discomfort to the user due to the output signal. In this embodiment, the target gains G1 and G3 have the same value. However, if the target gains G1 and G3 are different, the target gain G3 can be set to a value smaller than the target gain G1. As an example, the target gain G3 can be set to 0 and the target gain G3 can be set to 0.1. This is because the third state mainly corresponds to a state in which the electronic auscultation device 100 is left unattended, and therefore a very low output sound level is not a problem. On the other hand, in the first state, the user may be holding the electronic auscultation device 100 and listening to the output sound, so it may be preferable to allow the user to hear environmental sounds at a level that does not cause discomfort.

[0050] The gain setting unit 403 may be configured to gradually increase (change) the gain toward the target gain G2, rather than immediately changing the gain to the target gain G2, even when it determines that the non-auscultation state has transitioned to the auscultation state. The rate of increase (rate of change) of the gain does not need to be constant. Alternatively, the gain setting unit 403 may be configured to immediately change the gain to the target gain G1, when it determines that the auscultation state has transitioned to the non-auscultation state. The gain setting unit 403 may also be configured to gradually decrease the gain toward the target gain G1, rather than immediately changing the gain to the target gain G1, when it determines that the auscultation state has transitioned to the non-auscultation state. However, the absolute value of the rate of decrease (rate of change) of the gain due to the transition to the non-auscultation state is set to be greater than the absolute value of the rate of increase of the gain due to the transition to the auscultation state.

[0051] By configuring the gain setting unit 403 in this manner, the level of the output signal from the electronic auscultation device 100 gradually increases when transitioning from the non-auscultation state to the auscultation state. This prevents the sound level based on the output signal from momentarily increasing, which would cause discomfort to the user. On the other hand, when transitioning from the auscultation state to the non-auscultation state, the sound level based on the output signal quickly decreases, which prevents the vibration detection unit 200 from outputting a sound that would cause discomfort to the user, even if it detects vibrations other than those of a living body.

[0052] 4 is a flowchart of the gain determination process by the gain setting unit 403. In S10, the gain setting unit 403 calculates an evaluation value. In S11, the gain setting unit 403 compares the evaluation value with a first threshold value to determine whether the electronic auscultation device 100 is in an unstable non-auscultation state (first state). If the evaluation value is greater than the first threshold value, that is, if the electronic auscultation device 100 is determined to be in an unstable non-auscultation state, the gain setting unit 403 sets the target gain to G1 in S15.

[0053] If it is determined that the electronic auscultation device 100 is not in an unstable non-auscultation state (first state), the gain setting unit 403 compares the evaluation value with a second threshold value in S12 to determine whether the electronic auscultation device 100 is in a stable non-auscultation state (third state). If the evaluation value is equal to or less than the second threshold value, that is, if it is determined to be in a stable non-auscultation state, the gain setting unit 403 sets the target gain to G1 in S15. If it is determined that the electronic auscultation device 100 is not in a stable non-auscultation state (third state), the gain setting unit 403 determines that the electronic auscultation device 100 is in an auscultation state and sets the target gain to G2 in S13. In S14, the gain setting unit 403 notifies the adjustment unit 402 of the gain determined based on the target gain. As described above, if the target gain is G2, the gain setting unit 403 gradually increases the gain to be notified to the adjustment unit 402 from the current gain toward gain G2. After the gain reaches gain G2, the gain is kept constant at gain G2. When the target gain is G1, gain setting unit 403 immediately sets the gain to be notified to adjustment unit 402 to gain G1. When the target gain is G1, the gain to be notified to adjustment unit 402 can also be configured to gradually decrease from the current gain toward gain G1.

[0054] FIG. 5 shows an example of the change over time in the evaluation value and gain. Note that the evaluation value actually includes three values ​​for each of the three directions, but in FIG. 5 , it is represented as a single value for simplicity. From time t0 to time t1, the electronic auscultation device 100 is placed on a desk, and the evaluation value is equal to or less than the second threshold. Therefore, the gain setting unit 403 notifies the adjustment unit 402 of gain G1. When the user lifts the electronic auscultation device 100 from the desk, the evaluation value exceeds the second threshold at time t1, and then exceeds the first threshold at time t2. Because the evaluation value is within the range between the second and first thresholds from time t1 to time t2, the gain setting unit 403 gradually increases the gain notified to the adjustment unit 402 toward gain G2. However, because the evaluation value exceeds the first threshold at time t2, the gain setting unit 403 changes the gain notified to the adjustment unit 402 to gain G1 at time t2. Since the period from time t1 to time t2 is short, the gain is relatively small when time t2 is reached.

[0055] During the period from time t2 to time t3, the user is moving the electronic auscultation device 100 toward the subject, and the evaluation value is greater than the first threshold, so the gain setting unit 403 notifies the adjustment unit 402 of gain G1. For example, the user places the chestpiece 110 in contact with the subject and begins auscultation, causing the evaluation value to fall within the range between the second threshold and the first threshold from time t3 onward. Therefore, from time t3, the gain setting unit 403 gradually increases the gain notified to the adjustment unit 402 toward gain G2. As shown in FIG. 5 , at time t4, the gain notified to the adjustment unit 402 becomes gain G2, and thereafter, the gain setting unit 403 keeps the gain notified to the adjustment unit 402 constant at G2.

[0056] As described above, the movement of the electronic auscultation device 100 is detected, and based on the detection results, it is determined whether the electronic auscultation device 100 is in an auscultation state (state 2) in which auscultation is being performed, or in a non-auscultation state (states 1 and 3) in which auscultation is not being performed. If the electronic auscultation device 100 is in an auscultation state, the gain, which is a parameter for adjusting the level of the output signal, is increased toward gain G2. On the other hand, if the electronic auscultation device is not in an auscultation state, the gain is decreased toward gain G1 or gain G3. This configuration makes it possible to prevent the user from being annoyed by noise output when not auscultating. In other words, the level of the output signal (output sound) of the electronic auscultation device can be appropriately controlled.

[0057] Although the chestpiece 110 in FIG. 2 detects vibration of the diaphragm 206 based on the amount of received reflected light and outputs a biological sound signal, the configuration of the chestpiece 110 is not limited to that shown in FIG. 2 . FIG. 6 shows another configuration example of the chestpiece 110. As shown in FIG. 6 , the chestpiece 110 has a microphone 220 held by a holding member 201. The microphone 220 detects sound generated by vibration of the diaphragm 206 accompanying vibration of the biological surface and outputs a biological sound signal. The chestpiece 110 may further include a piezoelectric element that detects pressure due to vibration of the biological surface. The piezoelectric element detects pressure due to vibration of the biological surface directly or via the diaphragm 206 and outputs a biological sound signal indicating changes in pressure over time. The chestpiece 110 may further include an acceleration sensor that detects the acceleration of vibration of the biological surface. The acceleration sensor detects the acceleration of the vibrations on the body surface directly or via the diaphragm 206, and outputs a body sound signal indicating the change in acceleration over time. Furthermore, the chestpiece 110 may include a gyro sensor that detects the angular velocity of the vibrations on the body surface. The gyro sensor detects the angular velocity of the vibrations on the body surface directly or via the diaphragm 206, and outputs a body sound signal indicating the change in angular velocity over time.

[0058] Second Embodiment Next, a second embodiment will be described, focusing on the differences from the first embodiment. Fig. 7 is a block diagram of the electronic auscultation device 100 according to this embodiment. One difference from the configuration shown in Fig. 3 is that a first threshold, a second threshold, and a third threshold are stored in the storage unit 404. Note that the first threshold is greater than the third threshold, and the third threshold is greater than the second threshold.

[0059] The evaluation value in the first embodiment was the variance of acceleration in each of the x-axis, y-axis, and z-axis directions. In this embodiment, the variance of acceleration in the z-axis direction is used as the first evaluation value, and the variance of acceleration in each of the x-axis and y-axis directions is used as the second evaluation value. In addition, in the first embodiment, a single first threshold value was used to determine whether or not an unstable non-auscultation state (first state) is present. In this embodiment, two threshold values, a first threshold value and a third threshold value, are used to determine whether or not an unstable non-auscultation state (first state) is present.

[0060] In this embodiment, too, the three axial directions of the acceleration sensor included in the status detection sensor 300 are assumed to coincide with the x-, y-, and z-axis directions of the coordinate system CS. Therefore, the detected values ​​output by the status detection sensor 300 at each sampling period are accelerations in the x-, y-, and z-axis directions. If the relative angles between the three axial directions of the acceleration sensor and the three axial directions of the coordinate system CS are known, the accelerations in the x-, y-, and z-axis directions can be calculated based on the accelerations in the three axial directions output by the acceleration sensor. Therefore, the three axial directions of the acceleration sensor do not have to coincide with the x-, y-, and z-axis directions of the coordinate system CS.

[0061] In this embodiment, the gain setting unit 403 determines the movement state of the electronic auscultation device 100 to be an unstable non-auscultation state (first state) when the first evaluation value is greater than the first threshold or when the second evaluation value is greater than the third threshold. The gain setting unit 403 determines the movement state of the electronic auscultation device 100 to be a stable non-auscultation state (third state) when both the first evaluation value and the second evaluation value are equal to or less than the second threshold. The gain setting unit 403 determines the movement state of the electronic auscultation device 100 to be an auscultation state (second state) when the first evaluation value is equal to or less than the first threshold, the second evaluation value is equal to or less than the third threshold, and both the first evaluation value and the second evaluation value are greater than the second threshold.

[0062] As in the first embodiment, the second evaluation value being greater than the threshold value means that at least one of the x-axis variance value and the y-axis variance value is greater than the threshold value, the second evaluation value being equal to or greater than the threshold value means that at least one of the x-axis variance value and the y-axis variance value is equal to or greater than the threshold value, the second evaluation value being smaller than the threshold value means that both the x-axis variance value and the y-axis variance value are smaller than the threshold value, and the second evaluation value being equal to or less than the threshold value means that both the x-axis variance value and the y-axis variance value are equal to or less than the threshold value.

[0063] Furthermore, as described in the first embodiment, when the evaluation value is equal to the threshold value, it is arbitrary whether to determine that the evaluation value is greater than the threshold value or less than the threshold value.

[0064] In summary, in this embodiment, the criteria for determining a stable non-auscultation state (third state) are the same as in the first embodiment. On the other hand, in this embodiment, the criteria for determining an unstable non-auscultation state (first state) are different from those in the first embodiment. Specifically, the first evaluation value evaluates the instability of movement in the z direction, and the second evaluation value evaluates the instability of movement in a direction intersecting the z direction, more specifically, in a direction perpendicular to the z direction. In this embodiment, the third threshold value compared with the second evaluation value to determine whether or not the state is unstable non-auscultation is smaller than the first threshold value compared with the first evaluation value.

[0065] For example, after picking up the electronic auscultation device 100 from a desk, the user may hold the electronic auscultation device 100 in their hand for a while without moving it significantly, rather than immediately bringing the electronic auscultation device 100 into contact with the subject and starting auscultation. Furthermore, when auscultating multiple locations, the user may hold the electronic auscultation device 100 in their hand between auscultations without moving it significantly. Hereinafter, the state in which the user holds the electronic auscultation device 100 in their hand without moving it significantly will be referred to as the "user-held state." The user-held state is a non-auscultatory state, but the stability of the movement of the electronic auscultation device 100 is higher than when the electronic auscultation device 100 is picked up from a desk, for example.

[0066] To classify the user's holding state as a non-auscultation state, the first threshold value in the first embodiment may be set to a relatively small value. However, during auscultation, the state detection sensor 300 detects acceleration in the z-axis direction in response to vibrations on the surface of the living body. If the evaluation value in the z-axis direction exceeds the first threshold value due to this acceleration in the z-axis direction, the gain is changed to G1 even during auscultation, and the level of the living body sound becomes lower.

[0067] For this reason, in this embodiment, the evaluation value in the first embodiment is separated into a first evaluation value in the z direction and second evaluation values ​​in the x and y directions. The z direction is the direction in which the angle with the vibration direction of the biological surface is smaller than the x and y directions when detecting vibrations on the biological surface. The third threshold value, which is compared with the second evaluation value to determine whether the state is an unstable non-auscultation state (first state), is set smaller than the first threshold value, which is compared with the first evaluation value. This configuration accurately determines the user's holding state included in the unstable non-auscultation state, and suppresses the output of sounds that may be unpleasant to the user in the non-auscultation state.

[0068] 8 is a flowchart of the gain determination process in this embodiment. In S20, the gain setting unit 403 calculates a first evaluation value and a second evaluation value. In S21, the gain setting unit 403 compares the first evaluation value with a first threshold value to determine whether the electronic auscultation device 100 is in an unstable non-auscultation state (first state). If the first evaluation value is greater than the first threshold value, that is, if the electronic auscultation device 100 is determined to be in an unstable non-auscultation state, the gain setting unit 403 sets the target gain to G1 in S26.

[0069] If the first evaluation value is equal to or less than the first threshold, the gain setting unit 403 compares the second evaluation value with a third threshold to determine whether the electronic auscultation device 100 is in an unstable non-auscultation state (first state) in S22. If the second evaluation value is greater than the third threshold, that is, if the electronic auscultation device 100 is determined to be in an unstable non-auscultation state, the gain setting unit 403 sets the target gain to G1 in S26.

[0070] If it is determined that the electronic auscultation device 100 is not in the unstable non-auscultation state (first state), the gain setting unit 403 compares the first evaluation value and the second evaluation value with a second threshold value in S23 to determine whether the electronic auscultation device 100 is in the stable non-auscultation state (third state). If both the first evaluation value and the second evaluation value are equal to or less than the second threshold value, that is, if it is determined that the electronic auscultation device 100 is in the stable non-auscultation state, the gain setting unit 403 sets the target gain to G1 in S26. If it is determined that the electronic auscultation device 100 is not in the stable non-auscultation state (third state), the gain setting unit 403 determines that the electronic auscultation device 100 is in the auscultation state (second state) and sets the target gain to G2 in S24. The gain setting unit 403 notifies the adjustment unit 402 of the gain in S25. The gain change method is the same as in the first embodiment.

[0071] Figure 9 shows an example of the change over time in the evaluation value and gain. Note that the second evaluation value actually includes two values ​​for each of the two directions, but in Figure 9 it is shown as one value for simplicity. During the period from time t10 to time t11, the user picks up the electronic auscultation device 100 from the desk, and both the first evaluation value and the second evaluation value exceed the first threshold. Therefore, the gain setting unit 403 notifies the adjustment unit 402 of the gain G1.

[0072] The period from time t11 to time t17 corresponds to the user-held state. From time t11 to time t17, both the first evaluation value and the second evaluation value are below the first threshold, but are lower than the third threshold only sporadically. Therefore, from time t11 to time t17, except for the period when the second evaluation value is lower than the third threshold, the gain setting unit 403 notifies the adjustment unit 402 of the gain G1. Furthermore, during the period when the second evaluation value is lower than the third threshold, the gain setting unit 403 increases the gain notified to the adjustment unit 402 toward G2. However, because the period when the second evaluation value is lower than the third threshold is short, the gain notified to the adjustment unit 402 does not increase significantly. For example, in the first embodiment, the gain notified to the adjustment unit 402 is increased toward G2 during the period from time t11 to time t17.

[0073] The period from time t17 to time t18 corresponds to a state in which the user is moving the chestpiece 110 to bring it into contact with the non-measured person. As a result of the user bringing the chestpiece 110 into contact with the non-measured person and beginning auscultation, from time t18 onward, the first evaluation value falls within the range between the second threshold and the first threshold, and the second evaluation value falls within the range between the second threshold and the third threshold. Therefore, from time t18, the gain setting unit 403 gradually increases the gain notified to the adjustment unit 402 toward gain G2. As shown in FIG. 9 , at time t19, the gain notified to the adjustment unit 402 becomes G2, and thereafter, the gain setting unit 403 keeps the gain notified to the adjustment unit 402 constant at G2.

[0074] Note that after time t18, the first evaluation value increases sporadically. This is because the state detection sensor 300 detects acceleration in the z-axis direction due to vibrations on the surface of the living body. For example, if the first threshold in the first embodiment is set to the same value as the third threshold in this embodiment in order to classify the user's holding state as a non-auscultation state, the configuration of the first embodiment would change the gain to gain G1 each time the first evaluation value increases sporadically after time t18. On the other hand, in this embodiment, the first threshold applied to the first evaluation value and the third threshold applied to the second evaluation value are different, so the auscultation state can be accurately detected and a decrease in the gain during auscultation can be suppressed.

[0075] As described above, according to this embodiment, it is possible to accurately determine whether or not the electronic auscultation device is in a non-auscultation state, and therefore it is possible to appropriately control the level of the output sound of the electronic auscultation device based on the determined state.

[0076] The present invention can also be realized by a process in which a program that realizes one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., an ASIC) that realizes one or more of the functions.

[0077] This application claims priority based on Japanese Patent Application No. 2024-098975, filed on June 19, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. An electronic auscultation device comprising: an output means for outputting a biological sound signal indicating biological sounds based on vibrations of the surface of a living body; a detection means for detecting the movement state of the electronic auscultation device; and an adjustment means for adjusting the level of the biological sound signal with a gain set based on the movement state of the electronic auscultation device detected by the detection means, wherein the adjustment means sets the gain to a first gain when the movement state is a first state; sets the gain to a second gain larger than the first gain when the movement state is a second state with higher movement stability than the first state; and sets the gain to a third gain smaller than the second gain when the movement state is a third state with higher movement stability than the second state.

2. The electronic auscultation device according to claim 1, wherein the operating state of said electronic auscultation device is based on an evaluation value indicating the variation of a plurality of detection values ​​of said detection means over a predetermined past period.

3. The electronic auscultation device according to claim 2, wherein the evaluation value is a value based on the variance of the plurality of detection values ​​of the detection means over the predetermined past period.

4. An electronic auscultation device according to claim 2 or 3, wherein when the evaluation value is greater than a first threshold, the movement state of the electronic auscultation device is the first state; when the evaluation value is less than a second threshold, the movement state of the electronic auscultation device is the third state; when the evaluation value is less than the first threshold and greater than the second threshold, the movement state of the electronic auscultation device is the second state; and the first threshold is greater than the second threshold.

5. The electronic auscultation device according to claim 2 or 3, wherein the evaluation values ​​include a first evaluation value in a first direction and a second evaluation value in a second direction different from the first direction, wherein the first direction is a direction whose angle with the direction of vibration of the biological surface is smaller than that of the second direction when vibration of the biological surface is detected by the output means, wherein the movement state of the electronic auscultation device is the first state when the first evaluation value is larger than a first threshold value or the second evaluation value is larger than a third threshold value, wherein the movement state of the electronic auscultation device is the third state when both the first evaluation value and the second evaluation value are smaller than a second threshold value, wherein the movement state of the electronic auscultation device is the second state when the first evaluation value is smaller than the first threshold value, the second evaluation value is smaller than the third threshold value, and both the first evaluation value and the second evaluation value are larger than the second threshold value, and wherein the first threshold value is larger than the third threshold value, and the third threshold value is larger than the second threshold value.

6. An electronic auscultation device according to any one of claims 1 to 5, wherein the adjusting means makes the absolute value of the rate of increase when increasing the gain smaller than the absolute value of the rate of decrease when decreasing the gain.

7. An electronic auscultation device according to any one of claims 1 to 6, wherein the adjustment means, when setting the gain to the second gain, gradually increases the gain towards the second gain, and when the gain reaches the second gain, makes the gain constant at the second gain.

8. An electronic auscultation device according to any one of claims 1 to 7, wherein the first gain is equal to the third gain.

9. An electronic auscultation device according to any one of claims 1 to 8, wherein the detection means includes an acceleration sensor, and detects acceleration as a detection value for detecting the motion state of the electronic auscultation device.

10. An electronic auscultation device according to any one of claims 1 to 8, wherein the detection means includes a gyro sensor and detects angular velocity as a detection value for detecting the motion state of the electronic auscultation device.

11. An electronic auscultation device according to any one of claims 1 to 10, wherein the output means includes a membrane that is brought into contact with the surface of the living body, and a microphone that detects the sound generated by the vibration of the membrane and outputs the living body sound signal.

12. An electronic auscultation device according to any one of claims 1 to 10, wherein the output means includes a membrane that is brought into contact with the surface of the living body, a light source that irradiates light onto the membrane, and a light-receiving element that receives the light irradiated onto the membrane by the light source and reflected from the membrane, and outputs a signal corresponding to the amount of reflected light received as the living body sound signal.

13. An electronic auscultation device according to any one of claims 1 to 10, wherein the output means includes a piezoelectric element that detects pressure due to vibrations on the surface of the living body and outputs the living body sound signal.

14. An electronic auscultation device according to any one of claims 1 to 10, wherein the output means includes an acceleration sensor that detects the acceleration of vibrations on the surface of the living body and outputs the living body sound signal.

15. An electronic auscultation device according to any one of claims 1 to 10, wherein the output means includes a gyro sensor that detects the angular velocity of vibrations on the surface of the living body and outputs the living body sound signal.

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