Detection device and auscultation device

Abstract

[Problem] To provide a compact detection device capable of highly accurately measuring a high-frequency-band signal and a low-frequency-band signal of a subject. [Solution] A detection device (110) for detecting the vibration of a subject comprises: a diaphragm (206) including a reflection surface (206b) that moves in accordance with the vibration of the subject; a light-emitting means (202) for emitting a first light flux and a second light flux toward the reflection surface; a light-receiving means (204) for receiving the first light flux and the second light flux reflected on the reflection surface; and a conversion means for generating a signal related to the amount of displacement of the subject on the basis of the output of the light-receiving means. The light-receiving means has a light-receiving surface on which the first light flux and the second light flux move in a first direction in accordance with the movement of the reflection surface. The respective lengths of the first light flux and the second light flux on the light-receiving surface in the first direction differ from each other.

Description

Detection device and stethoscope

[0001] The present invention relates to a detection device and a stethoscope.

[0002] Patent Document 1 discloses an optical microphone that detects the movement amount of a diaphragm according to a change in the amount of received light as a detection device for detecting vibrations of a subject. Patent Document 2 discloses a stethoscope that detects vibrations in a high-frequency band of a subject with a piezoelectric microphone or an optical microphone and detects vibrations in a low-frequency band with an acceleration sensor.

[0003] U.S. Patent No. 6,154,551 U.S. Patent No. 11,000,257

[0004] A detection device capable of detecting vibrations of a subject with high precision is desired.

[0005] A detection device according to one aspect of the present invention is a detection device that detects vibrations of a subject, and includes a diaphragm including a reflecting surface that moves according to the vibrations of the subject, a light emitting means that emits a first light beam and a second light beam toward the reflecting surface, a light receiving means that receives the first light beam and the second light beam reflected by the reflecting surface, and a conversion means that generates a signal related to the displacement amount of the subject based on an output of the light receiving means. On the light receiving surface of the light receiving means, the first light beam and the second light beam move in a first direction according to the movement of the reflecting surface, and the lengths of the first light beam and the second light beam in the first direction on the light receiving surface are different from each other.

[0006] Other objects and features of the present invention will be described in the following embodiments.

[0007] According to the present invention, it is possible to provide a small-sized detection device capable of measuring signals in a high-frequency band and a low-frequency band of a subject with high precision.

[0008] These are schematic diagrams of the external appearance of the electronic stethoscope in each embodiment. Schematic diagram of the chestpiece configuration in Embodiment 1. Schematic diagram of the chestpiece configuration in Embodiment 1. Schematic diagram of the chestpiece operation in Embodiment 1. Schematic diagram of the change in the light-receiving range in Embodiment 1. Schematic diagram of the movement of reflected light in Embodiment 1. Explanatory diagram of the relationship between displacement and displacement signal in Embodiment 1. Schematic diagram of a modified chestpiece configuration in Embodiment 1. Schematic diagram of a modified chestpiece configuration in Embodiment 1. Schematic diagram of the movement of reflected light in Embodiment 1. Block diagram of the electronic stethoscope configuration. Schematic diagram of the chestpiece configuration in Embodiment 2. Schematic diagram of the chestpiece configuration in Embodiment 2. Schematic diagram of the movement of reflected light in Embodiment 2. Explanatory diagram of the relationship between intensity distribution and aperture in Embodiment 2. Schematic diagram of the movement of reflected light in Embodiment 3. Schematic diagram of the movement of reflected light in Embodiment 3. This is a schematic diagram of an example of the movement of reflected light in Example 3.

[0009] The embodiments of the present invention will be described in detail below with reference to the drawings. Although several features are described in each embodiment, not all of these features are necessarily essential to the present invention, and the features may be combined arbitrarily. Furthermore, in the attached drawings, the same reference numeral is used for identical or similar configurations, and redundant explanations are omitted. <Appearance of the electronic stethoscope> The appearance of the electronic stethoscope (stethoscope) 100 in each embodiment will be described with reference to Figures 1(a) and (b). In each embodiment, a coordinate system CS may be attached to the following drawings to explain the direction. The coordinate system CS is a three-dimensional orthogonal coordinate system having mutually orthogonal x, y, and z axes. In the following description, the positive z-axis direction may be referred to as the upper side, and the negative z-axis direction may be referred to as the lower side. Figure 1(a) is an external view of the electronic stethoscope 100 as seen from one direction, and Figure 1(b) is an external view of the electronic stethoscope 100 as seen from another direction. The electronic auscultation device 100 may be used, for example, for diagnosing living organisms. A living organism may be a human or an animal other than a human.

[0010] The electronic auscultation device 100 includes a chestpiece 110 and a gripping part 120. The chestpiece 110 includes a part that comes into contact with the living body during diagnosis using the electronic auscultation device 100. The chestpiece 110 may generate a displacement signal representing the amount of displacement of the living body surface (subject). Since the chestpiece 110 is used to detect the displacement of the living body surface, it may also be called a displacement detection device. Furthermore, since the chestpiece 110 is used to detect vibrations of the living body surface (subject), it may also be called a detection device (living vibration detection device).

[0011] The gripping portion 120 is the part that is gripped by the user of the electronic stethoscope 100 (for example, a doctor) when in use. Hereinafter, the user of the electronic stethoscope 100 may be simply referred to as the user. The gripping portion 120 may also be called a handle, grip, or handle. The chestpiece 110 is attached to the gripping portion 120. Specifically, the gripping portion 120 has a rod-like shape, and the chestpiece 110 is attached to one end of the gripping portion 120. The chestpiece 110 may be pivotable relative to the gripping portion 120. Alternatively, the chestpiece 110 may be fixed to the gripping portion 120.

[0012] In the examples shown in Figures 1(a) and 1(b), the electronic stethoscope 100 includes both a chestpiece 110 and a gripping section 120. Alternatively, the electronic stethoscope 100 may include only the chestpiece 110 and omit the gripping section 120. In this case, the chestpiece 110 may be powered through a cable (not shown), and the displacement signal may be output to an external device (e.g., an earphone) through this cable or another cable. Alternatively, the chestpiece 110 may incorporate a battery and a wireless communication module, and the displacement signal may be output to an external device (e.g., an earphone or a computer) via the wireless communication module.

[0013] <Example of Chestpiece Configuration> An example of the configuration of the chestpiece 110 according to Embodiment 1 will be described with reference to Figures 2(a) and 2(b). Figure 2(a) is an external view of the chestpiece 110 as seen from a certain direction. The upper part of Figure 2(b) is a cross-sectional view of the chestpiece 110, and the lower part of Figure 2(b) is a plan view of the chestpiece 110.

[0014] The chestpiece 110 includes, for example, a light-emitting means (light-emitting part) 202, a light-receiving means (light-receiving part) 204, a diaphragm 206, a housing 208, a collimator lens 900, and an aperture unit (aperture part) 704. In addition to the components shown in Figures 2(a) and 2(b), the chestpiece 110 may also have a circuit board on which circuit elements for controlling the operation of the chestpiece 110 are mounted, and other components.

[0015] The light-emitting means 202 is held in the housing 208 and has at least one light-emitting element that emits light using power supplied from a power source (not shown) (emitting a first luminous beam and a second luminous beam toward the reflective surface described later). Power may be supplied from an external power source to the chestpiece 110 (for example, the battery of the gripping part 120) or from a battery (not shown) mounted on the chestpiece 110. In Figures 2(a) and 2(b), the light-emitting means 202 is a light-emitting diode (LED), but it may be a laser diode (LD) or another compact light source.

[0016] The light-receiving means 204 is held in the housing 208 and has at least one light-receiving element that generates an electrical signal based on the amount of light received using power supplied from a power source (not shown). Power may be supplied from an external power source to the chestpiece 110 (for example, the battery of the gripping part 120) or from a battery (not shown) mounted on the chestpiece 110. In Figures 2(a) and 2(b), the light-receiving means 204 has a photodiode (PD). However, this embodiment is not limited to this and may have a more sensitive phototransistor (Ptr) or an avalanche photodiode (APD).

[0017] The housing 208 holds the diaphragm 206. The diaphragm 206 is a film made of resin or glass epoxy and functions as a vibrating part in sound and vibration. The diaphragm 206 extends along the xy plane of the coordinate system CS. The diaphragm 206 has a circular outer edge in the plan view. The diaphragm 206 is positioned to contact a biological surface. The diaphragm 206 constitutes part of the outer surface of the chestpiece 110. The diaphragm 206 has an outer surface 206a positioned to contact a biological surface when the electronic stethoscope 100 is in use, and an inner surface 206b on the opposite side of the outer surface 206a. The inner surface 206b is a reflective surface that moves in response to vibrations of the subject, such as a biological surface.

[0018] The diaphragm 206 has a fixed portion 206c that is fixed to the housing 208. The diaphragm 206 may be fixed to the housing 208 using an adhesive. 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 housing 208. 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 the displacement of the biological surface. In this vibration, the center of the diaphragm 206 becomes an antinode. The diaphragm 206 functions as a vibrating part.

[0019] The light-emitting means 202 irradiates light toward the diaphragm 206. The LED, which is the light-emitting means 202, emits divergent light with a large emission angle, and the irradiated light is collected by the collimator lens 900. The configuration can be completed without the collimator lens 900, but by increasing the amount of divergent light from the LED, the amount of light received by the light-receiving means 204 increases, improving the signal-to-noise ratio (SNR). Also, in order to realize a compact chestpiece 110, the collimator lens 900 has unnecessary parts cut off by a D-cut. The illumination light collected by the collimator lens 900 is stopped by the aperture unit 704, and the formed light beam passes through. The aperture unit 704 has a first aperture diaphragm 704a and a second aperture diaphragm 704b, which form the illumination light 211a and 211b directed toward the diaphragm 206, respectively. When comparing the sizes of the two aperture diaphragms 704a and 704b, the x-axis lengths of each aperture diaphragm in the CS coordinate system of the plan view in Figure 2(b) have the relationship "length of aperture diaphragm 704a < length of aperture diaphragm 704b". This relationship corresponds to the relationship La < Lb.

[0020] The illumination lights 211a and 211b each illuminate different areas of the inner surface 206b, and the illuminated light is reflected. That is, the inner surface 206b functions as a reflective surface. In the following description, the reflection of light by the inner surface 206b (i.e., the reflective surface) will be referred to as the reflection of light by the diaphragm 206. The diaphragm 206 may specularly reflect (in other words, mirror reflect) the light illuminated by the light-emitting means 202.

[0021] Illumination light 211a and illumination light 211b illuminate different regions 207a and 207b located approximately near the center 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.

[0022] The light-receiving means 204 receives the light beam emitted from the light-emitting means 202 and reflected by the inner surface (reflective surface) 206b of the diaphragm 206. The inner surface 206b of the diaphragm 206 moves in accordance with (in conjunction with) the vibration of the diaphragm 206. The amount of light in the light beam received by the light-receiving means 204 changes in accordance with the movement of the inner surface 206b of the diaphragm 206. The light-receiving means 204 or a conversion means included in the peripheral circuit generates a displacement signal representing the amount of displacement of the biological surface based on the amount of light received.

[0023] In this embodiment, the light-receiving means 204 has a light-receiving element (first light-receiving part) 204a and a light-receiving element (second light-receiving part) 204b, which are arranged to receive reflected light (first luminous beam) 212a and reflected light (second luminous beam) 212b, respectively. That is, the light-receiving means 204 has a light-receiving element 204a that receives the first luminous beam that has passed through the aperture diaphragm 704a, and a light-receiving element 204b that receives the second luminous beam that has passed through the aperture diaphragm 704b. The light-receiving means 204 may be arranged to receive all of the reflected light 212 when the diaphragm 206 is not in contact with the biological surface (i.e., when the diaphragm 206 is flat).

[0024] Although the light-emitting means 202 has an LED, this embodiment is not limited to this, and the light-emitting means 202 may have a component that emits parallel light so that light can be directed toward a specific area on the diaphragm 206. As one of the light-emitting means that forms parallel light, it is possible to use an LD with a small light-emitting point and use a collimator lens to form light that is more parallel. <Example of chestpiece operation> An example of the operation of the chestpiece 110 will be described with reference to Figures 3(a) and (b). As shown in Figures 3(a) and (b), the chestpiece 110 is used in contact with the biological surface 300. Specifically, the outer surface 206a of the diaphragm 206 of the chestpiece 110 is in close contact with the biological surface 300. As a result, the biological surface 300 and the diaphragm 206 vibrate together. Therefore, the chestpiece 110 detects the displacement of the diaphragm 206 in the z-axis direction as the displacement of the biological surface 300 in the z-axis direction. Displacement of the biological surface 300 can occur in response to bodily movements such as heartbeat and respiration of a human being with the biological surface 300.

[0025] Figure 3(a) is a cross-sectional view of the chestpiece 110 when the diaphragm 206 is flat. As described above, the light-emitting means 202 and the light-receiving means 204 (204a, 204b) are arranged so that when the diaphragm 206 is flat, the reflected light 212a and 212b are received by the light-receiving elements 204a and 204b, respectively. In Figure 3(a), Figure 4(a) shows a view A of the light-receiving means 204. Figures 4(a) to 4(d) are schematic diagrams of examples of changes in the light-receiving range.

[0026] In Figure 4(a), a coordinate system CS' is shown to illustrate the direction. 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 direction with a positive x' axis may be referred to as the light-emitting element side, and the direction with a negative x' axis may be referred to as the light-receiving element side.

[0027] The ends of the light-receiving elements 204a and 204b on the light-emitting side in the x' axis direction are designated as the light-receiving element ends 205a and 205b, respectively. Similarly, the ends of the reflected light 212a and 212b on the light-emitting side in the x' axis direction are designated as the reflected light ends 213a and 213b, respectively. In this case, the reflected light ends 213a and 213b are set to overlap with the light-receiving element ends 205a and 205b, respectively, or to be closer to the light-emitting side. If the reflected light ends 213a and 213b are set to be closer to the light-receiving elements than the light-receiving element ends 205a and 205b, respectively, there will be a range in which the amount of light received by the light-receiving elements 204a and 204b does not change even if the diaphragm 206 is displaced upward.

[0028] On the other hand, if the reflected light ends 213a and 213b are set closer to the light-emitting element side than the light-receiving element ends 205a and 205b, respectively, there is no range in which the amount of light received by the light-receiving elements 204a and 204b does not change. However, a portion of the reflected light 212a and 212b is not received, resulting in a decrease in light intensity. Therefore, it is preferable that the reflected light ends 213a and 213b are set to overlap with the light-receiving element ends 205a and 205b, respectively.

[0029] The light-receiving means 204 amplifies and outputs a photocurrent corresponding to the amount of light received. The peripheral circuit of the light-receiving circuit board (not shown) generates a displacement signal by converting the photocurrent output from the light-receiving means 204 into a voltage, and outputs the displacement signal to an external device. The peripheral circuit includes a conversion means that generates a signal relating to the amount of displacement of the subject based on the output of the light-receiving means 204. However, the light-receiving means 204 may be configured to include peripheral circuits such as a conversion means in addition to the light-receiving element.

[0030] Figure 3(b) shows a cross-sectional view of the chestpiece 110 when the biological surface 300 is displaced upward. The distance between the light-emitting means 202 and the upper surface of the diaphragm 206 is represented by d1. When the biological surface 300 is displaced upward, the distance d1 decreases. Accordingly, the region 207a of the diaphragm 206 that is irradiated with illumination light 211a moves closer to the light-emitting means 202, and the reflected light 212a also moves closer to the light-emitting means 202. As a result, the amount of reflected light 212a that reaches the photodetector 204a decreases, and the value of the displacement signal generated by the photodetector circuit board becomes smaller.

[0031] Similarly, the region 207b illuminated by the illumination light 211b moves closer to the light-emitting means 202, and the reflected light 212b also moves closer to the light-emitting means 202. As a result, the amount of reflected light 212b that reaches the photodetector 204b decreases, and the value of the displacement signal generated by the photodetector circuit board becomes smaller. In the state shown in Figure 3(b), as shown in Figure 4(b), the reflected light 212a does not reach the photodetector 204a at all, so the value of the displacement signal becomes (ideally) zero.

[0032] Furthermore, when the biological surface 300 is displaced upward, the A-view of the light-receiving means 204 becomes as shown in Figure 4(c). When the biological surface 300 is displaced further upward, the A-view of the light-receiving means 204 becomes as shown in Figure 4(d). In this case, the reflected light 212b no longer reaches the light-receiving element 204b at all, so the value of the displacement signal becomes (ideally) zero.

[0033] Thus, in the chestpiece 110, the light-emitting means 202 and the light-receiving means 204 are arranged such that the amount of light reaching the light-receiving means 204 changes in accordance with the movement of the diaphragm 206. Since the diaphragm 206 is displaced in conjunction with the displacement of the biological surface 300, the displacement signal generated by the light-receiving circuit board based on the amount of light received by the light-receiving means 204 represents the amount of displacement of the biological surface 300. In other words, the amount of displacement of the biological surface 300 may also be the amplitude of vibration. <Relationship between the amount of displacement of the biological surface and the amount of displacement on the light-receiving element> Referring to Figure 5, the relationship between the amount of displacement of the biological surface 300, the incident angle of the illumination light 211, and the amount of displacement of the reflected light 212 will be explained. Figure 5 is a schematic diagram of an example of the movement of reflected light. Position 401 indicates the reference position of the upper surface of the diaphragm 206. Position 402 indicates the position where the upper surface of the diaphragm 206 has been displaced upward by a displacement of d2 from position 401.

[0034] In Figure 5, the optical axis 403 is the optical axis of the illumination light 211. The angle of incidence of the light irradiated by the light-emitting means 202 (i.e., the illumination light 211) onto the diaphragm 206 is represented by θ. The angle of incidence θ of the illumination light 211 may also be defined by the angle between the optical axis 403 of the illumination light 211 and the normal to the upper surface of the diaphragm 206. The optical axis of the reflected light 212 when the upper surface of the diaphragm 206 is at position 401 is defined as optical axis 404. The optical axis of the reflected light 212 when the upper surface of the diaphragm 206 is at position 402 is defined as optical axis 405. Since the illumination light 211 is specularly reflected at the upper surface of the diaphragm 206, the reflection angle of the reflected light 212 is also θ. When the angle between the light-receiving means 204 and the upper surface 401 of the diaphragm 206 is denoted as φ, the displacement from the optical axis 404 to the optical axis 405 on the surface of the light-receiving means 204 is denoted as L1. In this case, the following relationship (1) holds.

[0035] L1 = (2 × d² × sinθ) / cos(θ - φ) ... (1) <Relationship between displacement amount and displacement signal of biological surface> Referring to Figure 6, the relationship between the displacement amount of the biological surface 300 and the displacement signal will be explained. Figure 6 is an explanatory diagram of the relationship between the displacement amount and the displacement signal. The graph in Figure 6 shows the relationship between the displacement amount of the biological surface 300 and the displacement signal ratio (percentage) Sa of the displacement signal when the diaphragm 206 is displaced upward compared to the displacement signal when the diaphragm 206 is flat. In Figure 6, the horizontal axis shows the displacement amount [mm] and the vertical axis shows the displacement signal ratio Sa [%].

[0036] Generally, in electronic stethoscopes, the displacement of the diaphragm 206 corresponding to the displacement of high-frequency signals is small, while the displacement of the diaphragm 206 corresponding to the displacement of low-frequency signals is large.

[0037] First, with reference to Figures 3(a), (b) through 6, the graph shown in 500a of Figure 6 will be explained. As the displacement of the biological surface 300 increases, the displacement L1 on the surface of the light-receiving means 204 increases, and the amount of reflected light 212a that reaches the light-receiving element 204a decreases linearly. Therefore, the displacement signal ratio Sa (percentage) on the light-receiving element 204a is expressed by the following equation (2).

[0038] (1 - L1 / La) × 100 …(2) Here, La (first luminous flux) is the length of the reflected light (first luminous flux) 212a shown in Figure 4(a) in the x' axis direction of the coordinate system CS' (the direction of movement of the light receiving means 204 on the light receiving surface (first direction)). The first direction is the direction in which the first luminous flux and the second luminous flux move on the light receiving surface of the light receiving means 204 in accordance with the movement of the reflective surface. By substituting equation (1) into equation (2), the following equation (3) is obtained.

[0039] Sa = (1 - (2 × d² × sinθ) / cos(θ - φ) / La) × 100 ... (3) Therefore, the displacement signal ratio Sa decreases linearly as the amount of displacement of the biological surface 300 increases, as shown by graph 500a. Let da be the amount of displacement of the diaphragm 206 at which the displacement signal ratio Sa becomes zero. When the amount of displacement exceeds da, the reflected light 212a no longer reaches the photodetector 204a, so even if the amount of displacement of the diaphragm 206 increases, the displacement signal ratio Sa remains zero.

[0040] Similarly, let's explain the graph shown in 500b of Figure 6. Of the reflected light 212b, the amount of light reaching the photodetector 204b decreases linearly. Therefore, the displacement signal ratio (percentage) Sb on the photodetector 204b is expressed by the following equation (4).

[0041] (1 - L1 / Lb) × 100 …(4) Here, Lb (second luminous flux) is the length of the reflected light (second luminous flux) 212b shown in Figure 4(a) in the x' axis direction (direction of movement of the light receiving means 204 on the light receiving surface) of the coordinate system CS'. Lb > La. By substituting equation (1) into equation (2), the following equation (5) is obtained.

[0042] Sb = (1 - (2 × d² × sinθ) / cos(θ - φ) / Lb) × 100 ... (5) Therefore, the displacement signal ratio Sb decreases linearly as the amount of displacement of the biological surface 300 increases, as shown by graph 500b. The amount of displacement of the diaphragm 206 at which the displacement signal ratio Sb becomes zero is denoted as db. When the amount of displacement exceeds db, the reflected light 212b no longer reaches the photodetector 204b, so even if the amount of displacement of the diaphragm 206 increases, the displacement signal ratio Sb remains zero. As shown in Figure 6, the light-emitting means 202 and the aperture diaphragms 704a and 704b are arranged such that the amount of light reaching the photodetectors 204a and 204b changes monotonically in response to the movement of the diaphragm 206 in one direction.

[0043] In Equations (3) and (5), it is shown that when the lengths La and Lb become smaller, the sensitivity of the chest piece 110 increases. Also, the angle φ formed by the incident angle θ, the light receiving means 204, and the upper surface 401 of the diaphragm 206 is a value within a range greater than 0 degrees and less than 90 degrees. The greater θ and φ are, the higher the sensitivity of the chest piece 110 becomes. Therefore, the chest piece 110 may be configured such that the incident angle θ increases. It is better to configure the angle φ formed by the light receiving means 204 to also increase. However, since the thickness of the chest piece 110 increases and the device becomes larger, controlling the angle φ formed by the incident angle θ and the light receiving means 204 for improving sensitivity is limited. Therefore, it is useful to control the length of the light beam in one direction of La and Lb.

[0044] Here, La < Lb holds. The reflected light 212a with a short length La in the x'-axis direction of the coordinate system CS' has a high sensitivity of the displacement signal ratio Sa with respect to the displacement of the diaphragm 206, and a sufficient signal value with respect to noise, and is used for detecting (acquiring) high-frequency displacement (a signal in a high-frequency band). On the other hand, the reflected light 212b with a long length Lb in the x'-axis direction of the coordinate system CS' is used for detecting (acquiring) low-frequency displacement (a signal in a low-frequency band). However, since the reflected light 212a used for acquiring high-frequency displacement has a short length in the x'-axis direction, it has high sensitivity, but the amount of light received by the light receiving element 204a is small, and there is a possibility that the SNR decreases. Therefore, by increasing the length Va of the reflected light 212a in the y'-axis direction (the second direction perpendicular to the moving direction (the first direction)) of the coordinate system CS', the amount of light received by the light receiving element 204a can be increased, and the decrease in SNR can be suppressed. Specifically, by increasing the length of the aperture stop 704a in the y-axis direction of the coordinate system CS shown in the plan view of FIG. 2(b), the amount of light of the reflected light (the first light beam) 212a can be increased. For this reason, when the length in the direction perpendicular to the moving direction on the light receiving surface of the light receiving means 204 of the reflected light 212a is Va, and the length in the direction perpendicular to the moving direction of the reflected light (the second light beam) 212b is Vb, it is preferable to satisfy the conditional expression Va > Vb.

[0045] In the above description, the light-emitting means 202, aperture unit 704, and light-receiving means 204 are arranged such that all of the reflected light 212 reaches the light-receiving means 204 when the diaphragm 206 is flat. However, this embodiment is not limited to this, and the light-emitting means 202, aperture diaphragm 704, and light-receiving means 204 may be arranged such that all of the reflected light 212 reaches the light-receiving means 204 when the diaphragm 206 is in an upwardly displaced position.

[0046] The chestpiece 110 according to the above embodiment can accurately detect the displacement of the biological surface 300. Specifically, the chestpiece 110 generates a displacement signal based on the displacement amount d2 of the reflective film. Therefore, the displacement of the biological surface 300 can be accurately detected regardless of the frequency at which the biological surface 300 vibrates. For example, even displacement of the biological surface 300 due to low-frequency vibrations of about 10 Hz can be accurately detected. Such low-frequency vibrations can be included, for example, in the displacement sound of the biological surface (heartbeat) caused by vibrations propagated from inside the body by the heartbeat.

[0047] On the other hand, with high-frequency vibrations above 100 Hz, the displacement d2 of the reflective film becomes small, so the change in the displacement signal ratio Sa also becomes small, making it easier to pick up noise and lowering the SNR. In one design example based on the results measured by the inventor, by making the sensitivity of the displacement signal ratio Sa about four times, it is possible to achieve a sound level equivalent to low-frequency biological sounds. Therefore, preferably, in addition to satisfying the condition equation 2.0 < Lb / La, it is useful to make the length Lb about four times the length La. With settings that deviate from this relationship, the displacement signal to noise becomes small, so the effect of improving the SNR may not be expected. More preferably, the condition equation 2.0 < Lb / La < 5.0 is satisfied. Even more preferably, the condition equation 3.0 < Lb / La < 5.0 is satisfied.

[0048] Also, the reflected light used for detecting the high-frequency displacement has a short length in the x'-axis direction and a small amount of light. Therefore, in FIG. 4(a), it is preferable to satisfy the conditional expression (the length of the reflected light 212a in the y'-axis direction) > 2 × (the length of the reflected light 212b in the y'-axis direction), that is, 2.0 < Va / Vb. More preferably, the conditional expression 2.0 < Va / Vb < 5.0 is satisfied. Even more preferably, the conditional expression 3.0 < Va / Vb < 5.0 is satisfied. Such high-frequency vibrations can be included, for example, in the displacement sounds (heart murmurs and breathing sounds) of the living body surface where the living body surface is displaced by vibrations propagated from the inside of the body due to pulsation. Also, in the chest piece 110, if the diaphragm 206 does not displace, the displacement signal does not change. Therefore, the ambient sound of the chest piece 110, the vibration and acceleration caused by the movement of the chest piece 110 are not detected as noise, and high-output characteristics with a high SNR can be obtained. <Specific Other Forms of Example 1> Referring to FIGS. 7(a) and 7(b), a modified example of the chest piece 110 will be described. In FIGS. 7(a) and 7(b), the differences from Example 1 will be described, and redundant descriptions will be omitted for points that may be the same as the description of Example 1. FIG. 7(a) is an external view of the chest piece 110 when viewed from a certain direction. The upper side of FIG. 7(b) is a cross-sectional view of the chest piece 110, and the lower side of FIG. 7(b) is a plan view of the chest piece 110.

[0049] The chest piece 110 has, for example, a light-emitting means 202, a light-receiving means 204, a diaphragm 206, a collimator lens 900, and an aperture stop (light-receiving aperture stop, stop unit) 705.

[0050] The illumination light collected by the collimator lens 900 forms illumination light 211 directed toward the diaphragm 206. The illumination light 211 illuminates a region 207 near the approximate center of the diaphragm 206 when the diaphragm 206 is not in contact with the biological surface. The light 212 reflected by the diaphragm 206 is focused by an aperture diaphragm 705 positioned in front of the light receiving means 204, and the formed light beam passes through. The aperture diaphragm 705 has two aperture diaphragms (first aperture diaphragm) 705a and an aperture diaphragm (second aperture diaphragm) 705b that form reflected light (illumination light) 214a and 214b directed toward the light receiving elements 204a and 204b, respectively. When comparing the sizes of the two aperture diaphragms 705a and 705b, the x-axis lengths of each aperture diaphragm in the CS coordinate system of the plan view in Figure 7(b) have the relationship "length of aperture diaphragm 705a < length of aperture diaphragm 705b". This relationship corresponds to the relationship La < Lb. The reflected light 214a and 214b are received by the photodetectors 204a and 204b, respectively.

[0051] Figures 8(a) to 8(d) show the A-view of the light receiving means 204 in the cross-sectional view of Figure 7(b). The end of the reflected light 212 on the light receiving element side in the x' axis direction, i.e., the reflected light end, is denoted as 205. Figure 8(a) shows the relationship between the reflected light 212 and the aperture diaphragm 705 when the diaphragm 206 is flat.

[0052] In this case, the reflected light end 205 is set to overlap with the light-receiving element ends 705c and 705d of the aperture diaphragms 705a and 705b in the x' axis direction, or to be closer to the light-emitting element side in the x' axis direction. If the reflected light end 205 is set closer to the light-receiving element than the light-receiving element ends 705c and 705d, there is a range in which the amount of light received by the light-receiving elements 204a and 204b does not change even if the diaphragm 206 is displaced upward. On the other hand, if the reflected light end 205 is set closer to the light-emitting element side, there is no range in which the amount of light received by the light-receiving elements 204a and 204b does not change, but a portion of the reflected light 212 is not received, resulting in a decrease in light intensity. Therefore, it is preferable that the reflected light end 205 is set to overlap with the light-receiving element ends 705c and 705d.

[0053] Figure 8(b) shows the relationship between the reflected light 212 and the aperture diaphragm 705 when the biological surface 300 is displaced upward. Since the reflected light 214a does not reach the photodetector 204a at all, the displacement signal value becomes (ideally) zero. When the biological surface 300 is displaced upward, the A view of the photodetector 204 is as shown in Figure 8(c). When the biological surface 300 is displaced further upward, the A view of the photodetector 204 is as shown in Figure 4(d). Here, since the reflected light 214b does not reach the photodetector 204b at all, the displacement signal value becomes (ideally) zero. <Other embodiments of Embodiment 1> As described above, a method for obtaining output characteristics with different sensitivities using a light beam formed by two illumination aperture diaphragms and two photodetectors has been explained. A method for obtaining output characteristics with different sensitivities using two photodetector aperture diaphragms and two photodetectors has also been explained. However, in this embodiment, the method for obtaining output characteristics with different sensitivities is not limited to these, and the following methods can also be considered.

[0054] For example, instead of two illumination aperture diaphragms, two diffractive optical elements (DOEs) with different characteristics may be used. The diffractive optical elements (diffractive elements) may be binary optical elements (BOEs) or computer-generated holograms (CGHs). By using DOEs with two different characteristics, illumination aperture diaphragms become unnecessary, and the light beam can be freely formed to match the position of the edge of the photodetector.

[0055] Furthermore, although the method described above uses one light-emitting element and two light-receiving elements, the method is not limited to this. For example, two light-emitting elements and one light-receiving element may be used, and the user may light up one of the light-emitting elements that requires the sensitivity they wish to measure to perform the measurement. Two light-emitting elements and two light-receiving elements may also be used. <Example of Electronic Stethoscope Configuration> Refer to Figure 9 for an example of the configuration of the electronic stethoscope 100. Figure 9 is a block diagram of an example of the configuration of the electronic stethoscope 100. The electronic stethoscope 100 may include a chestpiece 110 and a sound output unit 610.

[0056] The sound output unit 610 may be implemented by a plurality of circuit elements mounted on a circuit board included in the gripping unit 120. The sound output unit 610 outputs a sound signal based on the displacement signal generated by the chestpiece 110. The sound signal output by the sound output unit 610 may represent the biological sounds of a living organism (e.g., a human) having a biological surface 300. The sound signal may be transmitted to a sound output device 620 such as earphones or headphones. Alternatively, or in addition to this, the sound signal may be transmitted to a computer 630 (e.g., a personal computer, smartphone, tablet, etc.). The user can auscultate the sound represented by the sound signal (e.g., biological sounds) using the sound output device 620 or the computer 630.

[0057] The sound output unit 610 may have the components shown in Figure 9. The sound output unit 610 may also have components not shown in Figure 9 (for example, a filter circuit), or it may not have some of the components shown in Figure 9.

[0058] The sound output device 620 may be a wired type earphone or headphones, or a wireless type earphone or headphones. Therefore, the sound output unit 610 can output sound signals using both wireless and wired communication. First, the process for the sound output device 620 to output sound signals via wired communication will be described. The displacement signal output from the chestpiece 110 is amplified by the amplifier 615 and supplied to the wired communication unit 617. The wired communication unit 617 provides the amplified sound signal to the sound output device 620. The wired communication unit 617 is, for example, a 3.5 mm AUX terminal. The amplification gain of the amplifier 615 may be adjusted by the volume control unit 616. The sound output device 620 may be considered to constitute part of the electronic stethoscope 100. In this case, the electronic stethoscope 100 has a chestpiece 110, a gripping unit 120, and a sound output device 620.

[0059] Next, the process by which the sound output device 620 outputs an audio signal via wireless communication will be described. The displacement signal output from the chestpiece 110 is digitized by the A / D converter 611. The digital displacement signal is then amplified by the amplifier 612 and supplied to the encoder 613. The encoder 613 generates audio data for wireless communication by performing signal processing such as data compression and encoding on the amplified audio signal. The processing order of the amplifier 612 and encoder 613 may be reversed. Subsequently, the wireless communication unit 614, which conforms to a wireless communication standard such as Bluetooth®, provides the processed audio output data to the sound output device 620. The amplification gain of the amplifier 612 may be adjusted by the volume control unit 616. The electronic stethoscope 100 described above can output an audio signal via both wireless and wired communication, but it may also be possible to output an audio signal via only one of these communications.

[0060] The output of the sound signal to the computer 630 may be the same as the output of the sound signal to the sound output device 620. The computer 630 may visually display the waveform data generated based on the sound signal. The waveform data may be generated by the computer 630 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 (for example, the sound output device 620 or the computer 630).

[0061] The electronic auscultation device 100 can accurately detect the displacement of the biological surface 300. Specifically, it can accurately detect the displacement of the biological surface 300 regardless of the frequency at which the biological surface 300 vibrates. Therefore, the electronic auscultation device 100 enables good auscultation of both the relatively low-frequency biological sounds of about 10 Hz emitted by the body due to heartbeat and the relatively high-frequency biological sounds emitted by the body due to breathing.

[0062] <Example of Chestpiece Operation> Referring to Figures 10(a) and (b), an example of the configuration of the chestpiece 110 according to Embodiment 2 will be described. In Figures 10(a) and (b), the differences from Embodiment 1 will be explained, and redundant explanations will be omitted for points that may be the same as those described in Embodiment 1.

[0063] Figure 10(a) is an external view of the chestpiece 110 when the diaphragm 206 is not in contact with the biological surface, as seen from a certain direction. The upper part of Figure 10(b) is a cross-sectional view of the chestpiece 110, and the lower part of Figure 10(b) is a plan view of the chestpiece 110.

[0064] The chestpiece 110 includes, for example, a light-emitting means 202, a light-receiving means 204, a diaphragm 206, a housing 208, a collimator lens 900, an aperture diaphragm (illumination aperture diaphragm) 704, and an aperture diaphragm (light-receiving aperture diaphragm) 705.

[0065] The illumination light collected by the collimator lens 900 is stopped by the aperture diaphragms 704a and 704b, and the resulting illumination lights 211a and 211b illuminate different regions 207a and 207b located near the approximate center of the diaphragm 206. The aperture sizes of the aperture diaphragms 704a and 704b are the same as in Embodiment 1. That is, the lengths of each aperture diaphragm in the x-axis direction in the CS coordinate system of the plan view in Figure 10(b) have the relationship "length of aperture diaphragm 704a < length of aperture diaphragm 704b". This relationship corresponds to the relationship La < Lb.

[0066] The reflected light 212a and 212b reflected by the diaphragm 206 are stopped by aperture diaphragms 705a and 705b, respectively, which are positioned in front of the light receiving means 204. The aperture size of the aperture diaphragm 705 at this time is the same as that shown in the other specific form of Embodiment 1. That is, the length in the x' axis direction of each aperture diaphragm in the CS' coordinate system of Figure 11(a) has the relationship "length of aperture diaphragm 705a < length of aperture diaphragm 705b". This relationship corresponds to the relationship La < Lb. The formed light beams 215a and 215b are received by the light receiving elements 204a and 204b, respectively.

[0067] In the cross-sectional view of Figure 10(b), the A-view of the light-receiving means 204 is shown in Figures 11(a) to (d). Figure 11(a) shows the relationship between reflected light and the light-receiving aperture diaphragm when the diaphragm 206 is flat.

[0068] The end of the reflected light 212a on the light-emitting element side in the x' direction is defined as the reflected light end 212c, and the end of the reflected light 212b on the light-emitting element side in the x' direction is defined as the reflected light end 212d. Also, the end of the aperture diaphragm 705a on the light-emitting element side in the x' direction is defined as the light-receiving aperture diaphragm end 205c, and the end of the aperture diaphragm 705b on the light-emitting element side in the x' direction is defined as the light-receiving aperture diaphragm end 205d.

[0069] In this case, the reflected light ends 212c and 212d are set to overlap with the light-receiving aperture ends 705c and 705d, respectively, or to be closer to the light-emitting element side in the x' direction. If the reflected light ends are set closer to the light-receiving element side in the x' direction than the light-receiving aperture ends, there is a range in which the amount of light received by the light-receiving elements 204a and 204b does not change even if the diaphragm 206 is displaced upward. On the other hand, if the reflected light ends are set closer to the light-emitting element side in the x' direction than the light-receiving aperture ends, there is no range in which the amount of light received by the light-receiving elements 204a and 204b does not change, but some of the reflected light is not received, resulting in a decrease in light intensity. Therefore, it is preferable that the reflected light ends 212c and 212d are set to overlap with the light-receiving aperture ends 705c and 705d, respectively.

[0070] Figure 11(b) shows the relationship between reflected light and the light-receiving aperture diaphragm when the biological surface 300 is displaced upward. Since the reflected light 212a does not reach the light-receiving element 204a at all, the displacement signal value becomes (ideally) zero. When the biological surface 300 is displaced further upward, the A view of the light-receiving means 204 is as shown in Figure 4(c). When it is displaced even further upward, the A view of the light-receiving means 204 is as shown in Figure 4(d). Here, since the reflected light 214b does not reach the light-receiving element 204b at all, the displacement signal value becomes (ideally) zero. <Effects of Illumination Aperture Diaphragm and Light-Receiving Aperture Diaphragm> Here, the difference in the effects of the illumination aperture diaphragm and light-receiving aperture diaphragm compared to Example 1 will be explained using Figure 12. In Figures 12(a) to (e), coordinate systems CS' and CS'' are indicated to explain the directions. Coordinate system CS' is the same as that described in Example 1. 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 coordinate system CS. The x'' axis is parallel to the xz plane of coordinate system CS. This is a reproduction of the B view of the cross-sectional view in Figure 10(b). In the following description, the direction of the positive x'' axis may be referred to as the light-emitting element side, and the direction of the negative x'' axis may be referred to as the light-receiving element side.

[0071] Figure 12(a) shows the intensity distribution created by the light emitted from the light-emitting means 202 on the first surface of the collimator lens 900. 901 indicates the shape of the first surface of the collimator lens 900, and the light inside 901 is directed towards the aperture unit 704. In this case, the light-emitting means 202 uses an LED, as in Example 1, and the intensity distribution is not uniform.

[0072] Figure 12(b) shows the intensity distribution created by the light transmitted through the collimator lens 900 on the first surface of the aperture diaphragm 704. The aperture diaphragms 704a and 704b are arranged in the same configuration as the illumination aperture diaphragms shown in Figures 10(a) and 10(b). The aperture diaphragms 704a and 704b are positioned where the intensity distribution is relatively uniform, rather than at locations where the intensity distribution changes locally.

[0073] Figure 12(c) shows the intensity distribution created by the first surface of the aperture diaphragm 705. Due to the effect of positioning the aperture diaphragms 704a and 704b in positions where the intensity distribution is relatively uniform, the intensity distribution of the reflected light 212a and 212b reaching the aperture diaphragm 705 is relatively uniform. For example, when the diaphragm 206 is displaced upward, the reflected light 212a moves towards the light-emitting element in the x' direction. At this time, because the intensity distribution of the reflected light 212a is relatively uniform, the light reaching the photodetector 204a decreases linearly, as shown in Figure 6 of Example 1, relating the amount of displacement of the biological surface 300 to the displacement signal. Therefore, the displacement of the biological surface can be detected with high accuracy.

[0074] Next, we will explain the effect of installing the illumination aperture diaphragm at a location where the intensity distribution changes locally. Figure 12(d) shows the intensity distribution created by the light transmitted through the collimator lens 900 on the first surface of the aperture unit 704. Instead of the ideal aperture diaphragm 704a shown in Figure 12(b), the illumination aperture diaphragm 706a is installed at a location where the intensity distribution changes locally.

[0075] Figure 12(e) shows the intensity distribution created by the first surface of the aperture diaphragm 705. Because the aperture diaphragm (illumination aperture diaphragm) 706a is positioned where the intensity distribution changes locally, the intensity distribution of reflected light 216a reaching the aperture diaphragm (light-receiving aperture diaphragm) 707a changes locally. For example, when the diaphragm 206 is displaced upward, the reflected light 216a moves towards the light-emitting element in the x' direction. At this time, because the intensity distribution of the reflected light 216a is not uniform, it does not decrease in an ideal linear fashion like the relationship between the amount of displacement of the biological surface 300 and the displacement signal shown in Figure 6 of Example 1, and the graph shows little change near 100% and 0% of the displacement signal ratio Sa (percentage).

[0076] In this embodiment, a relatively uniform illumination light is formed by setting the illumination aperture diaphragm according to the intensity distribution of the light-emitting element. Consequently, the reflected light 212a and 212b reflected by the diaphragm 206 are at different positions, so by providing separate light-receiving aperture diaphragms, optimal reflected light is formed. In compact electronic stethoscopes, it is difficult to set the light-receiving elements 204a and 204b according to their respective reflected light, so this method is useful.

[0077] <Configuration with one light-emitting element and one light-receiving element> Here, we will describe a configuration with one light-emitting element and one light-receiving element. For example, we will explain the case where the user uses one light-emitting element and one light-receiving element, and lights up one of the light-emitting elements for which sensitivity is required to be measured, referring to Figures 13(a) to (c). An illumination aperture diaphragm, as shown in Figure 13(a), is installed between the light-emitting element and the light-receiving element. The illumination aperture diaphragm has a vertically elongated opening 708a. This illumination aperture diaphragm rotates 90° around the rotation axis 716, and when rotated, it becomes a horizontally elongated opening 708b.

[0078] When the diaphragm 206 is not in contact with the biological surface, if the user selects a high frequency, the illumination aperture diaphragm in Figure 13(a) will have a vertically elongated aperture 708a open. At this time, as shown in Figure 13(b), reflected light 222a is received on the light receiving means 204.

[0079] On the other hand, if the user selects a low frequency, the aperture diaphragm in Figure 13(a) opens to a horizontally elongated aperture 708b, and as shown in Figure 13(c), reflected light 222b is received on the light-receiving means 204. In this way, by rotating the light-receiving aperture diaphragm according to the frequency selection the user wants to measure, both high and low frequencies can be measured. <Other embodiments of Embodiment 3> Referring to Figures 14(a) to (c), other embodiments of Embodiment 3 will be described. An optical element as shown in Figure 14(a) is placed between the light-emitting element and the light-receiving element. The optical element is formed of diffractive optical elements 709a and 709b, which have different characteristics from each other. The diffractive optical elements 709a and 709b are placed in the optical path by rotating 90° around the rotation axis 717.

[0080] When the diaphragm 206 is not in contact with the biological surface, if the user selects a high frequency, the diffractive optical element 709a shown in Figure 14(a) is placed in the optical path, and the reflected light 223a is received on the light receiving means 204 as shown in Figure 14(b).

[0081] On the other hand, if the user selects a low frequency, the diffractive optical element 709b shown in Figure 14(a) is placed in the optical path, and the reflected light 223b is received on the light receiving means 204 as shown in Figure 14(c).

[0082] Here, the reflected light 223a and 223b produced by the diffractive optical elements 709a and 709b have different aspect ratios of the x' and y' axes in the CS' coordinate system. The reflected light 223a, which detects high frequencies, has a shorter length in the x' axis direction, allowing for highly sensitive detection of signals in the high-frequency band. Furthermore, since a shorter x' axis direction reduces the amount of light received and lowers the SNR, the y' axis direction is lengthened to increase the amount of light received.

[0083] In this way, by rotating the optical element to match the frequency selection the user wants to measure, it is possible to measure both high and low frequencies. As mentioned above, measuring both high and low frequencies is done by rotating the element, but this can also be achieved by shifting the element.

[0084] Referring to Figures 15(a) and 15(b), the means of achieving this by shifting the elements will be explained. When the diaphragm 206 is not in contact with the biological surface, if the user selects to acquire a high-frequency band signal, the relationship between the reflected light 224a and the light-receiving means 204 will be as shown in Figure 15(a). On the other hand, if the user selects to acquire a low-frequency band signal, the relationship between the reflected light 224b and the light-receiving means 204 will be as shown in Figure 15(b).

[0085] An illumination aperture diaphragm that forms reflected light is installed between the light-emitting element and the light-receiving element, and the reflected light moves as the illumination aperture diaphragm shifts. At this time, the reflected light 224a used to acquire high-frequency band signals is in the state shown in Figure 15(a) when the diaphragm 206 is not in contact with the biological surface. Therefore, when the diaphragm 206 is displaced, the reflected light 224a moves towards the light-emitting element on the x' axis of the CS' coordinate system. Since the amount of light received by the light-receiving means 204 decreases, it is necessary to design the output of the light-emitting element within a range where the SNR does not become a problem.

[0086] In each embodiment, the light beam received by the light-receiving means 204 includes a first light beam and a second light beam. The lengths La and Lb of the first and second light beams in the direction of movement on the light-receiving surface of the light-receiving means 204 are different from each other. Preferably, the respective areas (irradiation area, light quantity) of the first and second light beams on the light-receiving surface of the light-receiving element change according to the movement of the reflective surface (inner surface 206b). Preferably, the respective areas of the first and second light beams on the light-receiving surface of the light-receiving means change according to the movement of the reflective surface. Preferably, the first light beam is used to acquire a first vibration (high-frequency signal) at a first frequency (first frequency band), and the second light beam is used to acquire a second vibration (low-frequency signal) at a second frequency (second frequency band) different from the first frequency.

[0087] Preferably, the second frequency is lower than the first frequency, and the length of the second luminous beam in the first direction is longer than the length of the first luminous beam in the first direction. More preferably, the length La of the first luminous beam in the first direction and the length Lb of the second luminous beam in the first direction satisfy the condition 2.0 < Lb / La. This makes it possible to appropriately detect both the first vibration at the first frequency, where the amount of diaphragm movement is small, and the second vibration at the second frequency, where the amount of diaphragm movement is large.

[0088] Preferably, the length of the second luminous beam in the second direction perpendicular to the first direction is shorter than the length of the first luminous beam in the second direction. More preferably, the length Va of the first luminous beam in the second direction and the length Vb of the second luminous beam in the second direction satisfy the condition 2.0 < Va / Vb. This increases the amount of light in the first luminous beam used to detect the first vibration at the first frequency where the diaphragm movement is small, thereby enabling more appropriate detection of the first vibration.

[0089] Preferably, the conditions are La < Lb and Va > Vb, and La / Va ≤ Lb / Vb. This allows for more appropriate detection of the second vibration at the second frequency, where the diaphragm movement is large.

[0090] The amount of movement of the inner surface 206b of the diaphragm 206 is, for example, about 20 μm for low-frequency signals and about 1 μm for high-frequency signals. For this reason, the length Lb of the second luminous beam may be set to about 20 times the length La of the first luminous beam.

[0091] In each embodiment, it is sufficient that the lengths of the first and second luminous beams in the direction of movement on the light-receiving surface are different from each other. Therefore, the shape is not limited to the rectangular shape shown in Figures 4(a) to (d), but may be a square (La / Va = Lb / Vb = 1), or other shapes. The shapes of the first luminous beam and the second luminous beam may be different from each other. Also, the area of ​​the first luminous beam (first area: La × Va) and the area of ​​the second luminous beam (second area: Lb × Vb) may be different from each other. Furthermore, the shape of the second luminous beam does not have to be the same as the shape of the first luminous beam when rotated 90 degrees.

[0092] Each embodiment provides a compact detection device and an electronic auscultation device capable of accurately measuring high-frequency and low-frequency signals on the surface of a living organism.

[0093] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence.

Claims

1. A detection device for detecting vibrations of a subject, comprising: a diaphragm including a reflective surface that moves in accordance with the vibrations of the subject; a light-emitting means that emits a first luminous beam and a second luminous beam toward the reflective surface; a light-receiving means that receives the first luminous beam and the second luminous beam reflected by the reflective surface; and a conversion means that generates a signal relating to the displacement of the subject based on the output of the light-receiving means, wherein the first luminous beam and the second luminous beam move in a first direction in accordance with the movement of the reflective surface, and the lengths of the first luminous beam and the second luminous beam in the first direction on the light-receiving surface are different from each other.

2. The detection device according to claim 1, characterized in that the respective areas of the first luminous beam and the second luminous beam on the light-receiving surface of the light-receiving means change in accordance with the movement of the reflective surface.

3. The detection device according to claim 1 or 2, characterized in that the first luminous beam is used to acquire a first vibration of a first frequency, and the second luminous beam is used to acquire a second vibration of a second frequency different from the first frequency.

4. The detection device according to claim 3, characterized in that the second frequency is lower than the first frequency, and the length of the second luminous beam in the first direction is longer than the length of the first luminous beam in the first direction.

5. The detection device according to claim 4, characterized in that, when the length of the first luminous beam in the first direction is La and the length of the second luminous beam in the first direction is Lb, the condition 2.0 < Lb / La is satisfied.

6. The detection device according to claim 4 or 5, characterized in that the length of the second luminous beam in a second direction perpendicular to the first direction is shorter than the length of the first luminous beam in the second direction.

7. The detection device according to claim 6, characterized in that, when the length of the first luminous beam in the second direction is Va and the length of the second luminous beam in the second direction is Vb, the condition 2.0 < Va / Vb is satisfied.

8. The detection device according to any one of claims 1 to 7, further comprising an aperture unit disposed between the light-emitting means and the light-receiving means for shaping the first light beam and the second light beam.

9. The detection device according to claim 8, characterized in that the aperture unit includes a first aperture diaphragm for shaping the first light beam and a second aperture diaphragm for shaping the second light beam.

10. The detection device according to claim 9, characterized in that the light receiving means includes a first light receiving unit that receives the first light beam that has passed through the first aperture diaphragm, and a second light receiving unit that receives the second light beam that has passed through the second aperture diaphragm.

11. The detection device according to any one of claims 1 to 7, further comprising a diffraction element for shaping the first light beam and the second light beam.

12. A stethoscope comprising a detection device according to any one of claims 1 to 11, and a sound output unit that outputs a sound signal based on the signal relating to the amount of displacement.

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