Electroacoustic transducer

Abstract

An electroacoustic transducer of the present invention includes: a cylindrical external auditory canal insertion part that is part of a hollow housing to be worn in an ear of a user, and that is provided at an external auditory canal side of the housing; a measurement unit that measures electrostatic capacitance by using an electrode provided inside the external auditory canal insertion part; and an earpiece and a conductive layer, as a conductive part, arranged outside the external auditory canal insertion part and around the electrode.

Description

Electroacoustic transducer

[0001] The present disclosure relates to an electroacoustic transducer.

[0002] An apparatus is disclosed that includes a transducer circuit including a sensor circuit having an electrode, an electrical signal sensing circuit, a substrate that supports and at least partially surrounds the transducer circuit and the electrical signal sensing circuit, and a communication circuit (for example, Japanese Patent Application Laid-Open No. 2023-041713).

[0003] A capacitance sensing system adapted for non-invasive measurement of blood pulse (heart rate) is disclosed (for example, U.S. Patent Application Publication No. 2015 / 0051468). In this capacitance sensing system, the capacitance sensor is disposed near a pulse point of the skin (for example, the forehead region of the head) that indicates the pulsatile displacement of the skin tissue due to the pulsation of the blood vessel, and the sensor electrodes are disposed above the pulse point of the skin at a constant interval.

[0004] The invention described in Japanese Patent Application Laid-Open No. 2023-041713 has a plurality of sensor circuits that are capacitance sensors in a wearable device. Further, the invention described in U.S. Patent Application Publication No. 2015 / 0051468 senses the pulse by the capacitance sensor touching the skin outside the body. And it is generally known that by providing a plurality of pulse wave sensors, the detection accuracy in the case where there is a variation in the position of the device main body compared to the case where there is one pulse wave sensor can be improved. However, in an acoustic transducer of the type inserted into the ear canal, it is difficult to provide a plurality of sensors to measure the pulse wave due to physical space problems, and there has been a problem in suppressing the influence on the detection of the pulse wave due to the variation in the position of the device main body.

[0005] An object of the present disclosure is to provide an electroacoustic transducer capable of suppressing the influence of the variation in the position of the device main body in pulse wave detection.

[0006] An electroacoustic transducer according to the first embodiment is part of a hollow housing worn on the ear of a user, and includes a cylindrical ear canal insertion portion provided on the ear canal side of the housing, a measuring portion for measuring capacitance using electrodes provided inside the ear canal insertion portion, and a conductive portion disposed outside the ear canal insertion portion and around the electrodes.

[0007] In the second embodiment, the electroacoustic transducer is configured such that the conductive portion covers at least a portion of the external auditory canal insertion portion, in the electroacoustic transducer according to the first embodiment.

[0008] In the third embodiment of the electroacoustic transducer, the conductive portion is formed using an elastic member that has a current-collecting effect in the portion that comes into contact with the external auditory canal, in the electroacoustic transducer according to the second embodiment.

[0009] The electroacoustic transducer according to the fourth embodiment is an electroacoustic transducer according to the second embodiment, wherein the conductive portion is arranged to cover at least a part of the periphery of the ear canal insertion portion and is also arranged on the surface of at least a part of the ear canal insertion portion.

[0010] The fifth embodiment of the electroacoustic transducer is an electroacoustic transducer according to the first embodiment, wherein the conductive part is arranged on the surface of at least a part of the external auditory canal insertion part.

[0011] The sixth embodiment of the electroacoustic transducer is an electroacoustic transducer according to any one of the first to fifth embodiments, wherein the ear canal insertion portion between the conductive portion and the electrode is formed using an insulator.

[0012] The seventh embodiment of the electroacoustic transducer is an electroacoustic transducer according to any one of the first to fifth embodiments, wherein the conductive portion is arranged in the circumferential direction centered on the electrode and at positions facing the electrode on either side.

[0013] The electroacoustic transducer according to the eighth embodiment is an electroacoustic transducer according to any one of the first to fifth embodiments, wherein the electrode is a cylindrical metal housing provided in a signal output driver located inside the ear canal insertion portion.

[0014] An electroacoustic transducer according to the ninth embodiment further includes a calculation unit that calculates biological information based on the capacitance measured by the measurement unit, in an electroacoustic transducer according to any one of the first to fifth embodiments.

[0015] According to the disclosed technology, the influence of fluctuations in the position of the device body can be suppressed in pulse wave detection.

[0016] This is a cross-sectional view showing the overall configuration of the electroacoustic converter according to this embodiment. This is a cross-sectional view showing the overall configuration of the electroacoustic converter according to the embodiment. This is an exploded perspective view of the driver portion according to this embodiment. This is an exploded perspective view of the driver portion according to this embodiment. This is a top view of the driver. This is a side view of the driver. This is a cross-sectional view showing the driver portion according to this embodiment. This is a diagram showing a mounting method for measuring capacitance using a metal housing as an electrode. This is a diagram showing a mounting method for measuring capacitance using a metal housing as an electrode. This is a diagram showing a mounting method for measuring capacitance using a metal housing as an electrode. This is a schematic diagram of the electroacoustic converter according to this embodiment when it is installed. This is an explanatory diagram for explaining the flow from detection to output by the electroacoustic converter according to this embodiment. This is a flowchart showing an example of the output processing flow according to this embodiment. This is an example of measurement results measured by the measurement unit according to this embodiment. This is an example of biological information calculated by the calculation unit according to this embodiment.

[0017] Hereinafter, the electroacoustic converter 100 according to this embodiment will be described with reference to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios. Furthermore, this disclosure is not limited in any way to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of this disclosure.

[0018] (Summary of this embodiment) When adding a pulse wave sensing function to earphones, a limitation is that when using an optical pulse wave sensor, it is necessary to place one or more optical pulse wave sensors on the surface of the earphone that touches the skin. In the case of acoustic pulse wave sensing, a limitation is that it is necessary to seal the ear canal.

[0019] Furthermore, in the case of earphones that use capacitive pulse wave sensing, the capacitive sensor pads are laid out in areas that come into contact with the surface of the auricle or outside the ear canal (for example, near the tragus). In such earphones, a challenge has been that even slight changes in the capacitance can cause large fluctuations when the earphone body vibrates or the wearing state changes due to body movement or user operation, resulting in noise in pulse wave detection. In addition, arranging multiple capacitive sensor pads to suppress noise is a major constraint in earphones where miniaturization is required.

[0020] Therefore, in this embodiment, an electroacoustic transducer for insertion into the ear canal is provided with a capacitance sensor that can be inserted into the ear canal, and at least one of an earpiece having a current-collecting effect and a conductive layer is provided around the capacitance sensor. This configuration allows for the detection of pulse waves from changes in the charge distribution of at least one of the earpiece and the conductive layer.

[0021] (Configuration of the Electroacoustic Transducer) As shown in Figure 1, the electroacoustic transducer 100 according to this embodiment has a hollow housing 40 that is worn on the user's ear and houses various functional components inside. The electroacoustic transducer 100 also has a cylindrical ear canal insertion portion 42 having a hollow portion 42A, which is part of the housing 40 and is provided on the ear canal side of the housing 40 when worn on the user's ear. A conductive layer 412a is provided around the ear canal insertion portion 42 as a conductive layer. The conductive layer 412a only needs to be provided in at least a part of the circumferential direction centered on the ear canal insertion portion 42, and it is preferable that it be provided in a position opposite to the metal housing 2 of the driver 1 (see Figure 3), which will be described later, in the circumferential direction. Here, the positions opposite to the metal housing 2 of the driver 1 are, for example, the upper and lower and left and right positions around the ear canal insertion portion 42 when viewed from the direction of insertion into the ear canal (i.e., the direction of arrow FR in Figure 1). The same applies to the positions opposite each other across the metal housing 2 of the driver 1, so a detailed explanation will be omitted. In Figure 1, the arrow UP indicates the upper direction in the vertical direction of the electroacoustic transducer 100.

[0022] Furthermore, the electroacoustic transducer 100 has a signal output driver 1 provided inside the ear canal insertion portion 42. It is sufficient that at least a portion of the driver 1 is provided inside the ear canal insertion portion 42, and it is preferable that more than half of the driver 1 is provided inside the ear canal insertion portion 42.

[0023] Furthermore, the electroacoustic transducer 100 includes a playback unit 50 that outputs a signal from the driver 1, a measurement unit 48 that measures capacitance using the metal housing 2 (see Figure 3) of the driver 1 as an electrode, a calculation unit 52 that calculates biological information based on the capacitance measured by the measurement unit 48, and an output unit 53 that outputs the calculation results from the calculation unit 52.

[0024] The measurement unit 48, the playback unit 50, the calculation unit 52, and the output unit 53 are mounted on a printed circuit board 103 (see Figure 2) located inside the housing 40. The measurement unit 48 may function as, for example, a CDC (Capacitance to Digital Converter). The calculation unit 52 may be, for example, an MCU (Micro Controller Unit) or a DSP (Digital Signal Processor).

[0025] Furthermore, the electroacoustic transducer 100 has an earpiece 113. The earpiece 113 is also called an ear tip, ear pad, or ear cap, and is made of an elastic material such as silicone rubber. In this embodiment, the earpiece 113 is silicone rubber mixed with a conductive filler such as metal powder or carbon black, which is a conductive elastic material. The earpiece 113 has a hemispherical contact portion 113a that deforms to match the shape of the ear canal when worn and adheres closely to the wall surface of the ear canal, and a cylindrical portion 113b that is fitted into the ear canal insertion portion 42. When the earpiece 113 is fixed to the ear canal insertion portion 42 via the cylindrical portion 113b, the hemispherical contact portion 113a is positioned to cover the entire circumference of the metal housing 2 of the driver 1. The contact portion 113a of the earpiece 113 may have a slit. If the contact portion 113a has a slit, the contact portion 113a covers a part of the metal housing of the driver 1. In this case, if the contact portion 113a has a slit, it is preferable that the main body portion of the contact portion 113a (i.e., the portion other than the slit) is positioned to cover the metal housing 2 of the driver 1 on either side. The user wearing the electroacoustic transducer 100 can more easily distinguish ambient sounds because the earpiece 113 has a slit, compared to when the earpiece 113 does not have a slit.

[0026] (Example of Electroacoustic Transducer) An example of the electroacoustic transducer of this embodiment will now be described. As shown in Figure 2, the housing 40 of the electroacoustic transducer of this embodiment is formed by fitting together a main housing 101a and a front housing 101b. In Figure 2, the direction indicated by arrow FR is the front of the electroacoustic transducer in the front-to-back direction, and the direction indicated by arrow UP is the top of the electroacoustic transducer in the up-to-down direction. Furthermore, the direction indicated by arrow FR is the direction in which the electroacoustic transducer is inserted into the external auditory canal, and therefore indicates the side of the user's eardrum when the user wears the electroacoustic transducer.

[0027] The main housing 101a is a hollow, cylindrical component, and its rear opening is covered by a cover 102. Inside the main housing 101a, a printed circuit board 103 is positioned opposite the opening. The printed circuit board 103 is a board on which electronic components that function as a measurement unit 48, a regeneration unit 50, a calculation unit 52, and an output unit 53 are mounted.

[0028] A battery 106 is positioned in front of the printed circuit board 103 via a battery cushion 107 and a battery cap 108.

[0029] As shown in Figure 2, a housing rubber 109 is provided on the outer circumference of the main housing 101a. The housing rubber 109 is a cylindrical elastic member fitted onto the outer circumference of the main housing 101a, which reduces contact with the ear and prevents water from entering the housing 40.

[0030] As shown in Figure 2, the front housing 101b is positioned to close the front opening of the cylindrical main housing 101a. The front housing 101b has an overall shape of a frustoconical oblique cone, with a portion of its periphery slightly raised toward the eardrum (i.e., in the direction of the arrow FR in Figure 2). Furthermore, the front housing 101b in this embodiment is made of an insulator such as synthetic resin.

[0031] An external auditory canal insertion portion 42 is provided at the front of the front housing 101b, projecting toward the eardrum from the apex of a frustum of an oblique cone. The external auditory canal insertion portion 42 is cylindrical in shape and is provided on a part of the front housing 101b, with openings at both the front and rear, connecting the inside and outside of the front housing 101b. A driver 1, which has a cylindrical case, is installed inside the external auditory canal insertion portion 42. Therefore, a positioning portion 111 for the driver 1 is provided close to the front opening of the external auditory canal insertion portion 42, and the driver 1 is fixed to the inner surface of the external auditory canal insertion portion 42 by engaging the front end of the driver 1 with this positioning portion 111. The rear end of the driver 1 is positioned near the front end of the front housing 101b. The driver 1 includes a magnetic circuit for generating an output signal, a diaphragm, etc., within a cylindrical case, and a suitable well-known structure is used.

[0032] As shown in Figure 2, an earpiece 113 is fixed to the outer circumference of the ear canal insertion portion 42. The earpiece 113 has a hemispherical portion 113a that adheres to the wall surface of the ear canal, at the tip of a cylindrical portion 113b that fits onto the outer circumference of the ear canal insertion portion 42. An earpiece mounting groove 412 is provided on the outer circumference of the ear canal insertion portion 42, while a fitting portion 113c is provided on the inner circumference of the cylindrical portion 113b of the earpiece 113, as shown in Figure 2. The earpiece 113 is fixed to the ear canal insertion portion 42 by the fitting portion 113c engaging with the earpiece mounting groove 412. In addition, a conductive layer 412a is provided on the surface of the earpiece mounting groove 412 in this embodiment. The conductive layer 412a is formed from a paint mixed with a conductive filler such as metal powder or carbon black, a conductive plating, or a metal member. In other words, when the earpiece 113 is fixed to the ear canal insertion portion 42, the conductive earpiece 113 and the conductive layer 412a of the earpiece mounting groove 412 come into electrical contact. Hereinafter, the earpiece 113 and the conductive layer 412a may also be referred to as the conductive part.

[0033] Next, we will explain the specific configuration of driver 1.

[0034] Figure 3 is an exploded perspective view of the driver 1 according to this embodiment, viewed from one side in the direction of the central axis O; Figure 4 is an exploded perspective view of the driver 1 according to this embodiment, viewed from the other side in the direction of the central axis O; Figure 5A is a top view of the driver 1; Figure 5B is a side view of the driver 1; and Figure 6 is a cross-sectional view along the line IV-IV. The configuration of the driver 1 will be described below based on these figures.

[0035] The driver 1 mainly consists of a cylindrical metal housing 2 forming the outer shell, which houses a diaphragm assembly 3, a magnetic circuit 4 for driving the diaphragm assembly 3, a plate member 5 connected to the magnetic circuit 4, a screen 6 provided inside the plate member 5, and terminals 7 provided on the outer surface of the plate member 5. The metal housing 2 is made of a conductive material that forms electrodes.

[0036] More specifically, the cylindrical metal housing 2 has an outer shape where the diameter of one end in the direction of the central axis O gradually decreases towards the tip, and a sound-emitting opening 2a is formed on one end face. On the other hand, the other end face of the metal housing 2 is left open.

[0037] The diaphragm assembly 3 has a diaphragm 10 made of pulp, film, or the like, supported by an annular frame 11. The diaphragm 10 has a flat circular central surface 10a in the center, and an annular edge portion 10b is formed on one side of the periphery of the central surface 10a in the direction of the central axis O. A voice coil 12 (coil) wound in a cylindrical shape coaxial with the central axis O is connected to the back surface (the other side in the direction of the central axis O) of the peripheral portion of the central surface 10a of the diaphragm 10, and the vibration of the voice coil 12 is transmitted to the diaphragm 10. Two lead wires 12a of the wire forming the coil extend outward from the voice coil 12.

[0038] The magnetic circuit 4 consists of a magnet 20, a pole piece 21 connected to one polarity of the magnet 20, and a yoke 22 connected to the other polarity. The pole piece 21 and the yoke 22 are made of a magnetic material.

[0039] The magnet 20 is cylindrical in shape with a larger diameter than the voice coil 12 and is arranged coaxially with the voice coil 12. The magnet 20 has polarity in the direction of the central axis O, with one side in the direction of the central axis O having one polarity (e.g., south pole) and the other side in the direction of the central axis O having the other polarity (e.g., north pole).

[0040] The pole piece 21 is annular in shape and is positioned on the outer circumference of the voice coil 12. A stepped portion 21a is formed on the peripheral edge of one side of the pole piece 21 in the direction of the central axis O, into which the frame 11 of the diaphragm assembly 3 engages. The pole piece 21 also has a notch 21b for passing the two lead wires 12a of the voice coil 12.

[0041] The yoke 22 is composed of a center pole 30, whose tip is positioned on the inner circumference side of the voice coil 12 and which extends along the direction of the central axis O, and a disc-shaped flat plate portion 31 that extends radially outward from the base of the center pole 30 and is connected to the magnet 20.

[0042] The center pole 30 is formed from a cylindrical portion 30a at the tip and a conical portion 30b at the base. The diameter of the conical portion 30b widens from the tip, which is the boundary with the cylindrical portion 30a, towards the base (the other side in the direction of the central axis O) along the direction of the central axis O.

[0043] Specifically, the conical portion 30b expands in diameter from the tip to the base, becoming larger in diameter than the voice coil 12, but is inclined to a degree that prevents interference between the voice coil 12 and the center pole 30 even when the voice coil 12 vibrates due to current flow. More specifically, as shown in Figure 6, the tip of the conical portion 30b is located approximately the same as the other end of the voice coil 12 in the direction of the central axis O. Note that the tip position of the conical portion 30b is not limited to this position, and it is sufficient if it is located radially opposite the inner circumferential surface of the voice coil 12. Furthermore, the diameter of the base of the conical portion 30b is formed on the outer circumferential side than the outer circumferential surface of the voice coil 12, and in this embodiment in particular, it is formed close to the inner diameter of the magnet 20.

[0044] The flat plate portion 31 has a disk shape with a diameter slightly larger than the outer diameter of the magnet 20. At three positions on the flat plate portion 31 where it straddles the root portion of the center pole 30, three ventilation holes 31a are formed to communicate the space A on one side (the surface on one side in the direction of the central axis O) connected to the magnet 20 of the flat plate portion 31 and the space B on the other side (the surface on the other side in the direction of the central axis O) of the said one surface. Each ventilation hole 31a is a circular hole, and a part of the root portion of the center pole 30 is also cut along the shape of each ventilation hole 31a. Also, a part of the opening on one side of each ventilation hole 31a is blocked by the magnet 20.

[0045] Also, an arc-shaped notch 31b for passing the two lead wires 12a of the voice coil 12 is formed in a part of the periphery of the flat plate portion 31.

[0046] The plate member 5 has a disk shape with a step on its periphery and is attached to the other side surface of the flat plate portion 31 of the yoke 22. Thereby, the plate member 5 partitions the space B communicating with each ventilation hole 31a on the other side surface of the flat plate portion 31 of the yoke 22. A ventilation hole 5a for communicating the internal space and the outside is formed at the center position of the plate member 5. Also, an arc-shaped notch 5b for passing the two lead wires 12a of the voice coil 12 is formed in a part of the periphery of the plate member 5.

[0047] The screen 6 is a circular film-shaped air-permeable acoustic resistance material and is provided so as to cover the ventilation hole 5a within the space formed by the plate member 5. An annular double-sided tape 6a is attached to the other side surface of the screen 6, and the screen 6 is attached to the plate member 5 via the double-sided tape 6a.

[0048] The terminal 7 is a circular plate material with a central hole 7a formed therein. The surface on one side in the direction of the central axis O is adhered to the plate member 5, and an electrode 7b is formed on the surface on one side in the direction of the central axis O. Also, an arc-shaped notch 7c for passing the two lead wires 12a of the voice coil 12 is formed in a part of the periphery of the terminal 7.

[0049] The notches 21b of the pole piece 21, 31b of the flat plate portion 31 of the yoke 22, 5b of the plate member 5, and 7c of the terminal 7 are all located on approximately the same line parallel to the central axis O, and the two lead wires 12a of the voice coil 12 are connected to the electrodes 7b of the terminal 7 by passing through the respective notches 21b, 31b, 5b, and 7c. Although not shown, UV adhesive is applied along the circumferential direction to the annular gap between the metal housing 2 and the plate member 5, and this UV adhesive seals the gap between the metal housing 2 and the plate member 5. The two lead wires 12a passing through the notch 5b of the plate member 5 are also bonded with UV adhesive. Therefore, in the driver 1 configured in this way, the space on the back side of the diaphragm 10 is a closed space through the screen 6 to the ventilation hole 5a of the plate member 5.

[0050] In the driver 1 configured as described above, when an electrical signal is sent to the electrode 7b of the terminal 7, the voice coil 12 is energized via the lead wire 12a, and the voice coil 12 vibrates in response to the electrical signal, causing the diaphragm 10 to vibrate and sound to be emitted from the sound emission opening 2a.

[0051] Next, we will explain the implementation method for measuring capacitance using the metal housing 2 as an electrode.

[0052] In the first implementation method, as shown in Figure 7A, a lug 60 that can be soldered to the metal housing 2 is formed. In this case, the measuring unit 48 measures the capacitance using the metal housing 2 as an electrode in a self-capacitance manner.

[0053] In the second mounting method, as shown in Figure 7B, in addition to the first mounting method, electrodes 64 are printed around the insertion hole in the mounting substrate 62, which has an insertion hole for inserting the driver 1. In this case, the measurement unit 48 measures the capacitance using a mutual capacitance method, with the metal housing 2 as RX and the electrodes 64 printed on the mounting substrate 62 as TX.

[0054] In the third mounting method, as shown in Figure 7C, in addition to the first mounting method, electrodes 66 are printed on the flexible substrate 65, and the flexible substrate 65 is wrapped around a portion of the circumferential surface of the metal housing 2. As a result, the electrodes 66 are formed over a portion of the circumferential surface of the metal housing 2. In this case, the measuring unit 48 measures the capacitance using a mutual capacitance method, with the metal housing 2 as RX and the electrodes 66 printed on the flexible substrate 65 as TX.

[0055] In the fourth mounting method, as shown in Figure 7D, the metal housing 2 mounted in the first mounting method is divided in the circumferential direction. A solderable lug 60 is formed on each of the divided metal housings 68. In this case, the measuring unit 48 measures the capacitance using a mutual capacitance method with the multiple metal housings 68 as TX and RX.

[0056] The calculation unit 52 calculates biological information based on the capacitance measurement results from the measurement unit 48. For example, it calculates pulse rate, blood flow rate, and sweating amount as biological information. The calculation unit 52 also removes baseline fluctuations from the capacitance measurement results and extracts fluctuations due to pulsation. For example, the calculation unit 52 removes baseline fluctuations by differentiating and denoising the measured capacitance data.

[0057] The output unit 53 outputs the calculation results or measurement results of biological information. For example, it transmits the calculation results or measurement results of biological information to another terminal via wireless communication. Alternatively, the driver 1 outputs the calculation results or measurement results of biological information as audio. Alternatively, it transmits the calculation results or measurement results of biological information to an external output device via wireless communication, and the external output device outputs the calculation results or measurement results of biological information as audio or displays them.

[0058] (Operation of the electroacoustic transducer) When the housing 40 of the electroacoustic transducer 100 is attached to the user's ear, and a command for measuring biological information is received wirelessly from the user's terminal (not shown), the measurement unit 48 measures the capacitance using the metal housing 2 as an electrode. Then, the calculation unit 52 calculates the biological information based on the capacitance measurement result by the measurement unit 48, and the output unit 53 outputs the calculation result of the biological information.

[0059] (Operation) Figure 8 is a schematic diagram of the electroacoustic transducer 100 according to this embodiment when it is attached to the user's ear. Figure 9 is a schematic diagram showing the flow of the electroacoustic transducer 100 detecting the user's pulse wave. The operation of the electroacoustic transducer 100 will be described below based on these figures.

[0060] As shown in Figure 8, the electroacoustic transducer 100 is fitted to the user's ear by inserting the earpiece 113 of the electroacoustic transducer 100 into the external auditory canal C of the user's ear.

[0061] Figure 9 is an explanatory diagram illustrating the process leading up to the occurrence of a change in capacitance detected by the electroacoustic transducer 100 according to this embodiment. The following description will focus on the case where a user is wearing the electroacoustic transducer 100 (see Figure 8). Here, the arrows from step S10 to step S15 indicate the causal relationship between events (i.e., the starting point of the arrow indicates the cause, and the ending point of the arrow indicates the effect). Thick arrows indicate a large impact, and dashed arrows indicate a small impact.

[0062] In step S10, a change in blood volume occurs due to pulsation. In this embodiment, the events described below are mainly caused by a change in blood volume in the user's external auditory canal.

[0063] In step S11, a change in capacitance occurs in the ear canal. Since the relative permittivity of blood is around 80, the electrostatic induction caused by the change in blood volume due to pulsation in step S10 results in a change in capacitance in the user's ear canal.

[0064] In step S12, expansion and contraction of the external auditory canal occur. Specifically, the change in blood volume due to pulsation in step S10 causes expansion and contraction of the blood vessels in the user's external auditory canal. That is, when the blood volume in the external auditory canal increases, the blood vessels in the external auditory canal expand, and the external auditory canal contracts. On the other hand, when the blood volume in the external auditory canal decreases, the blood vessels in the external auditory canal contract, and the external auditory canal expands.

[0065] In step S13, a change in the charge distribution of the earpiece 113 occurs. Specifically, in step S11, a change in capacitance in the ear canal causes a change in the charge distribution of the earpiece 113 due to electrostatic induction. Also, in step S12, expansion and contraction of the ear canal cause deformation of the earpiece 113, and this deformation causes a change in the charge distribution of the earpiece 113.

[0066] In step S14, a change in the charge distribution of the conductive layer 412a occurs. Specifically, in step S11, a change in capacitance in the ear canal causes a change in the charge distribution of the conductive layer 412a due to electrostatic induction. Also, in step S12, expansion and contraction of the ear canal causes a change in the distance between the ear canal and the conductive layer 412a, and this change in distance causes a change in the charge distribution of the conductive layer 412a. Furthermore, since the earpiece 113 and the conductive layer 412a are in electrical contact, a change in the charge distribution of the earpiece 113 in step S13 causes a change in the charge distribution of the conductive layer 412a.

[0067] In step S15, a change in the capacitance of the metal housing 2 occurs. Specifically, a change in the capacitance of the metal housing 2 occurs due to electrostatic induction caused by a change in the charge distribution of the earpiece 113 in step S13. Also, a change in the capacitance of the metal housing 2 occurs due to electrostatic induction caused by a change in the charge distribution of the conductive layer 412a in step S14. Furthermore, a change in the capacitance of the metal housing 2 occurs due to electrostatic induction caused by a change in capacitance in the ear canal in step S11, and also due to the change in distance caused by the expansion and contraction of the ear canal in step S12.

[0068] Here, we will explain, in comparison with conventional capacitive pulse wave sensing, the point at which the mounting position of the electroacoustic transducer 100 shifts when an external force is applied to the housing 40 in the direction indicated by the arrow in Figure 8. External forces applied to the housing 40 include, for example, the user's body movement, operation of the electroacoustic transducer 100, and external wind pressure. Note that in Figure 8, arrow UP indicates the upward direction, arrow DW indicates the downward direction, arrow LF indicates the left direction (i.e., the direction of insertion into the external auditory canal), and arrow RG indicates the right direction (i.e., the direction of removal from the external auditory canal).

[0069] If a capacitance sensor pad is positioned on the surface of the auricle or outside the external auditory canal (for example, near the tragus), changes in the position of the earphone due to body movement or other factors will cause a change in the distance from the capacitance sensor pad to the ear surface. As a result, a large change will occur in the capacitance measured by the capacitance sensor pad.

[0070] On the other hand, in the electroacoustic transducer 100 of this embodiment, capacitance is measured using the metal housing 2 of the driver 1, which is provided inside the ear canal insertion portion 42, as an electrode. The earpiece 113 that contacts the ear canal is arranged to cover the circumferential direction of the ear canal insertion portion 42, and the conductive layer 412a is arranged around the ear canal insertion portion 42. Therefore, even if the position of the electroacoustic transducer 100 changes in the left-right direction due to body movement, the metal housing 2, which acts as an electrode, will move in parallel in the left-right direction within the ear canal, but the distance between the metal housing 2 and the ear canal will not change significantly, and thus no significant change will occur in the measured capacitance.

[0071] Furthermore, if the capacitance sensor pad is positioned in contact with the surface of the auricle or outside the external auditory canal (for example, near the tragus), when the position of the earphone changes vertically due to body movement, the earpiece 113 acts as a pivot point, causing a change in the distance from the capacitance sensor pad to the ear surface. As a result, a large change occurs in the capacitance measured by the capacitance sensor pad.

[0072] On the other hand, in the electroacoustic transducer 100 of this embodiment, if the position of the electroacoustic transducer 100 changes in the vertical direction due to body movement or the like, parts of the conductive part will approach the external auditory canal and parts will move away from it. Therefore, the charge distribution of the conductive part will be reciprocal, and some of the capacitance fluctuations will be canceled out, so there will be no significant change in the measured capacitance. Note that the change in capacitance due to pulsation occurs all around the external auditory canal, and unlike the case of the change in capacitance due to body movement or the like, it will not be suppressed by cancellation.

[0073] Figure 10 is a flowchart showing an example of the output processing flow according to this embodiment. The output processing is a process for outputting the user's biometric information calculated from the change in capacitance detected by the electroacoustic transducer 100. The output processing is a process that is repeatedly executed, for example, when the user is wearing the electroacoustic transducer 100.

[0074] In step S100 of Figure 10, the measurement unit 48 of the electroacoustic transducer 100 quantifies the change in capacitance. Specifically, the measurement unit 48 measures the change in capacitance of the metal housing 2 that occurred in step S15 (see Figure 9) and converts it into a digital value (hereinafter referred to as "capacitance value").

[0075] In step S101, the calculation unit 52 acquires the change in capacitance value. Specifically, the calculation unit 52 acquires the change in capacitance value of the metal housing 2 measured by the measurement unit 48 (see Figure 11).

[0076] Figure 11 shows an example of measurement results measured by the measurement unit 48 according to this embodiment. The graph shown in Figure 11 shows the change in the capacitance value of the metal housing 2 measured by the measurement unit 48 while the user is wearing the electroacoustic transducer 100. As shown in Figure 11, the measurement unit 48 detects the capacitance value that changes over time. That is, the measurement unit 48 detects the change in the volume of blood in the user's ear canal, as well as the change in the capacitance of the metal housing 2 due to the expansion and contraction of the ear canal. Note that the graph generally slopes downward from around 30 seconds to around 39.5 seconds, which reflects the changes in temperature and humidity inside the ear canal due to the user continuously wearing the electroacoustic transducer 100.

[0077] In step S102 of Figure 10, the calculation unit 52 removes baseline fluctuations from the change in capacitance value. Specifically, the calculation unit 52 obtains acceleration data of the change in capacitance value by taking the second derivative of the capacitance value data acquired in step S100 (see Figure 12).

[0078] Figure 12 shows an example of biological information calculated by the calculation unit 52 according to this embodiment. The graph shown in Figure 12 is a graph obtained by taking the second derivative of the change in capacitance value measured by the measurement unit 48. By taking the second derivative of the change in capacitance value, the acceleration of the change in capacitance value can be obtained. Here, if the acceleration of the change in capacitance value is a positive value, it means that the rate of increase of the capacitance value is increasing or the rate of decrease is decreasing. Also, if the acceleration of the change in capacitance value is a zero value, it means that there is no change in the capacitance value. Also, if the acceleration of the change in capacitance value is a negative value, it means that the rate of increase of the capacitance value is decreasing or the rate of decrease is increasing. As shown in Figure 12, the graph showing the acceleration of the change in capacitance value from around 30 seconds to around 45 seconds generally repeats up and down movements 14 times. For example, the up and down movement of the graph from around 30 seconds to around 31 seconds is counted as one up and down movement. This reflects the change in the capacitance value of the metal housing 2 due to changes in the volume of blood in the user's external auditory canal, and the expansion and contraction of the external auditory canal. Furthermore, since changes in blood volume in the external auditory canal, as well as expansion and contraction of the external auditory canal, are due to pulsation, the user's heart rate can be estimated by the number of up-and-down movements of the graph showing the acceleration of changes in capacitance value.

[0079] In step S103 of Figure 10, the calculation unit 52 calculates the heart rate. Specifically, the calculation unit 52 calculates the heart rate using the acceleration data of the change in capacitance value acquired in step S102.

[0080] In step S104, the calculation unit 52 outputs the calculated heart rate. Specifically, the calculation unit 52 outputs the heart rate data calculated in step S103 from the output unit 53. The output unit 53, for example, transmits the heart rate data to the user's terminal. Then, the calculation unit 52 terminates the output process.

[0081] (Summary of this embodiment) The electroacoustic transducer 100 of this embodiment measures capacitance using a metal housing 2 provided inside a cylindrical ear canal insertion portion 42 as an electrode, and includes a conductive portion arranged outside the ear canal insertion portion 42 and around the metal housing 2. Therefore, the electroacoustic transducer 100 of this embodiment can suppress the influence of changes in the position of the device body when detecting pulse waves.

[0082] The electroacoustic transducer 100 of this embodiment has an earpiece 113 made of conductive silicone rubber surrounding the ear canal insertion portion 42. Therefore, according to the electroacoustic transducer 100 of this embodiment, the user's pulse wave can be detected by changes in the charge distribution of the earpiece 113.

[0083] The electroacoustic transducer 100 of this embodiment has an earpiece 113 made of conductive silicone rubber surrounding the ear canal insertion portion 42, and a conductive layer 412a provided on the surface of the ear canal insertion portion 42. Therefore, the electroacoustic transducer 100 of this embodiment can detect the user's pulse wave with greater accuracy compared to cases where only one of the earpiece 113 or the conductive layer 412a is present.

[0084] The electroacoustic transducer 100 of this embodiment has a conductive layer 412a provided on the surface of the ear canal insertion portion 42. Therefore, according to the electroacoustic transducer 100 of this embodiment, the user's pulse wave can be detected by changes in the charge distribution of the conductive layer 412a.

[0085] In this embodiment, the electroacoustic transducer 100 has a front housing 101b located between the conductive part and the metal housing 2, which is constructed using an insulator. Therefore, with this embodiment, the electroacoustic transducer 100 forms a capacitor between the conductive part and the metal housing 2, and the detected capacitance fluctuations can be amplified.

[0086] In this embodiment, the electroacoustic transducer 100 has conductive parts arranged in a circumferential direction centered on the metal housing 2, and positioned opposite each other across the metal housing 2. Therefore, according to this embodiment, the influence on changes in capacitance when the position of the electroacoustic transducer 100 changes in the vertical direction can be suppressed.

[0087] In this embodiment, the electroacoustic transducer 100 measures changes in capacitance using a metal housing 2 provided on the driver 1, which is located inside the ear canal insertion portion 42, as an electrode. Therefore, with this embodiment, the electroacoustic transducer 100 can suppress fluctuations in capacitance due to body movement, etc., to a smaller extent compared to the case where a capacitance detection pad is placed outside the ear canal.

[0088] The electroacoustic transducer 100 of this embodiment includes a calculation unit 52 that calculates the heart rate based on the capacitance measured by the measurement unit 48. Therefore, according to the electroacoustic transducer 100 of this embodiment, biological information can be obtained from changes in capacitance.

[0089] [Other Embodiments] In this embodiment, the electroacoustic transducer 100 detected a change in the capacitance of the metal housing 2 by using the earpiece 113 and the conductive layer 412a as conductive parts. However, the electroacoustic transducer 100 is not limited to this, and may be configured to detect a change in the capacitance of the metal housing 2 by using only one of the earpiece 113 and the conductive layer 412a. When only the earpiece 113 is used as the conductive part, the electroacoustic transducer 100 can detect a change in the capacitance of the metal housing 2 caused by electrostatic induction due to a change in the charge distribution of the earpiece 113 (see step S13 in Figure 9). Also, when only the conductive layer 412a is used as the conductive part, the electroacoustic transducer 100 can detect a change in the capacitance of the metal housing 2 caused by electrostatic induction due to a change in the charge distribution of the conductive layer 412a (see step S14 in Figure 9).

[0090] In this embodiment, the ear canal insertion portion 42 is cylindrical in shape, and the case in which an earpiece 113 is attached and used has been described, but the shape of the ear canal insertion portion 42 is not limited to this. The ear canal insertion portion 42 may be, for example, a shape used in a semi-canal type or inner-ear type electroacoustic transducer that does not require an earpiece 113, with an elliptical, flattened opening. According to the electroacoustic transducer 100 of this embodiment, the user's pulse wave can be detected by the change in the charge distribution of the conductive layer 412a.

[0091] In this embodiment, the measurement unit 48 measured capacitance using the metal housing 2 as an electrode, but the electrode used by the measurement unit 48 is not limited to the metal housing 2. Capacitance may be measured by placing a capacitance sensor pad made of a flexible substrate in the ear canal insertion portion 42, separate from the metal housing 2 of the driver 1. According to the electroacoustic transducer 100 of this embodiment, the user's pulse wave can be detected by the change in capacitance measured by the capacitance sensor pad.

[0092] Furthermore, the configuration of the electroacoustic converter 100 described in the above embodiment is merely an example, and may be modified as needed without departing from the main purpose.

[0093] Furthermore, the processing flow described in the above embodiment is merely an example, and unnecessary steps may be deleted, new steps added, or the processing order rearranged, as long as it does not deviate from the main purpose.

[0094] Furthermore, the operation of the processor in the above embodiment may not be performed by a single processor, but may be performed by multiple processors located in physically separate locations working together. Also, the order of the processor's operations is not limited to the order described in the above embodiment, but may be changed as appropriate.

Claims

A part of a hollow housing that is worn in the user's ear, comprising a cylindrical ear canal insertion portion provided on the ear canal side of the housing, A measuring unit that measures capacitance using electrodes provided inside the external auditory canal insertion portion, A conductive portion is disposed outside the external auditory canal insertion portion and around the electrode, An electroacoustic transducer that includes [a specific component]. 　 The conductive portion is arranged to cover at least a portion of the periphery of the external auditory canal insertion portion. The electroacoustic transducer according to claim 1. 　 The conductive part is formed using an elastic member that has a current-collecting effect in the portion that comes into contact with the external auditory canal. The electroacoustic transducer according to claim 2. 　 The conductive portion is arranged to cover at least a portion of the periphery of the ear canal insertion portion and is also arranged on the surface layer of at least a portion of the ear canal insertion portion. The electroacoustic transducer according to claim 2. 　 The conductive portion is disposed on the surface of at least a portion of the external auditory canal insertion portion. The electroacoustic transducer according to claim 1. 　 The ear canal insertion portion between the conductive portion and the electrode is formed using an insulator. An electroacoustic converter according to any one of claims 1 to 5. 　 The conductive portion is arranged in the circumferential direction centered on the electrode, at positions facing the electrode on either side of it. An electroacoustic converter according to any one of claims 1 to 5. 　 The electrode is a cylindrical metal housing provided in a signal output driver located inside the external auditory canal insertion portion. An electroacoustic converter according to any one of claims 1 to 5. 　 The system further includes a calculation unit that calculates biological information based on the capacitance measured by the measurement unit. An electroacoustic converter according to any one of claims 1 to 5.

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