Wearable device

Abstract

To provide a wearable device capable of measuring information on the ear or the periphery of the ear more accurately.SOLUTION: A wearable device mounted on the ear of a user includes: a microphone for collecting a sound around the wearable device; a vibrator that abuts on the ear of the user when the wearable device is worn and vibrates in response to an electric signal based on an output signal of the microphone; and a body part that abuts on the entrance of the external acoustic meatus or is inserted into it when the wearable device is worn. One surface that abuts on the entrance of the external acoustic meatus of the body part or one surface facing the direction that the external acoustic meatus extends is provided with a strain gauge for measuring vibration of air in the inside of the external acoustic meatus.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a wearable device. [Background technology]

[0002] Wearable devices such as earphones, earphone microphones, and hearing aids are well known. Technologies have been developed to sense various information about the user of such wearable devices by incorporating sensors. For example, Patent Document 1 discloses a bone conduction earphone microphone having a bone conduction sound vibration detection element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-205273 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when trying to detect some information from inside or around the ear using a wearable device, as in the technology described above, it is necessary to capture even weak changes in measurement values ​​using a small device that can be worn on the ear.

[0005] The present invention has been made in consideration of the above points, and aims to realize a wearable device that can measure information about the inside of the ear or the surrounding area of ​​the inside of the ear with higher accuracy. [Means for solving the problem]

[0006] A wearable device according to one embodiment of the present disclosure is a wearable device worn on a user's ear, and comprises: a microphone that collects sounds around the wearable device; a vibrator that contacts the user's ear when the wearable device is worn and vibrates in response to an electrical signal based on the output signal of the microphone; and a main body that contacts or is inserted into the entrance of the ear canal when the wearable device is worn, and a strain gauge that measures vibrations of air inside the ear canal is provided on one side of the main body that contacts the entrance of the ear canal or on one side facing the direction in which the ear canal extends. [Effects of the Invention]

[0007] The disclosed technology makes it possible to realize a wearable device that can measure information about the inside of the ear or the area around the inside of the ear with higher accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view illustrating a hearing aid according to a first embodiment. [Figure 2] 1 is a perspective view illustrating a hearing aid according to a first embodiment worn on a user's ear. [Figure 3] FIG. 2 is a view of the main body of the hearing aid according to the first embodiment, viewed from the contact surface side. [Figure 4] 1 is a block diagram illustrating the configuration of a hearing aid according to a first embodiment. [Figure 5] FIG. 2 is a plan view illustrating the strain gauge according to the first embodiment. [Figure 6] 1 is a cross-sectional view (part 1) illustrating a strain gauge according to a first embodiment. FIG. [Figure 7] FIG. 2 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. [Figure 8] FIG. 10 is a side view illustrating a pulse wave detector according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view illustrating a pulse wave detector according to a second embodiment. [Figure 10]FIG. 10 is a block diagram illustrating the configuration of a pulse wave detector according to a second embodiment. [Figure 11] 10A and 10B are a plan view and a cross-sectional view showing an example of a detection element included in a strain gauge according to a third embodiment. [Figure 12] 10A and 10B are a perspective view, a plan view, and a cross-sectional view showing an example of a detection element included in a strain gauge according to a fourth embodiment. [Figure 13] 10A and 10B are a perspective view, a plan view, and a cross-sectional view showing another example of a detection element included in a strain gauge according to the fourth embodiment. [Figure 14] 10A and 10B are a perspective view, a plan view, and a cross-sectional view showing still another example of a detection element included in a strain gauge according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the invention will be described with reference to the drawings. In each drawing, the same components may be assigned the same reference numerals. Furthermore, in each drawing, mutually orthogonal X, Y, and Z directions may be defined. In this case, in the X direction, the starting point (base) side of the arrow may be referred to as the X- side, and the ending point (arrowhead) side of the arrow may be referred to as the X+ side. The same applies to the Y and Z directions. Furthermore, in the description of each drawing, a description of components that are the same as components already described may be omitted.

[0010] First Embodiment In the first embodiment, a hearing aid is shown as an example of a wearable device that is worn on the ear of a user.

[0011] Fig. 1 is a perspective view illustrating a hearing aid according to a first embodiment. Fig. 2 is a perspective view illustrating a hearing aid according to a first embodiment worn on a user's ear. Fig. 3 is a view of the main body of the hearing aid according to the first embodiment as seen from the contact surface side. Fig. 4 is a block diagram illustrating the configuration of the hearing aid according to the first embodiment. The main body and contact surface will be described in detail later.

[0012] The hearing aid 1 shown in Figures 1 to 4 has a main body 11, an ear hook portion 12, a vibration unit 13, and a strain gauge 100. As shown in Figures 1 and 2, the hearing aid 1 is a hearing aid that is worn over the user's ear.

[0013] Hearing aid 1 may be a monaural hearing aid consisting of one earphone as shown in Figure 1, or may be a binaural hearing aid consisting of two earphones as shown in Figure 1. When hearing aid 1 is a binaural hearing aid, the hearing aid for the right ear and the hearing aid for the left ear may each have the same configuration.

[0014] The main body 11 is a hollow member made of, for example, resin. The main body 11 abuts against or is inserted into the entrance of the ear canal when the user wears the hearing aid 1 in their ear. The main body 11 has an abutment surface 11a. Here, the abutment surface 11a refers to (i) the surface of the main body 11 that abuts against the entrance of the ear canal, or (ii) the surface that faces the direction in which the ear canal extends, when the hearing aid 1 is worn in the user's ear. In this embodiment, the surface of the main body 11 opposite the abutment surface 11a is referred to as the back surface 11b. The part of the main body 11 consisting of the pinna 501 and the ear canal 502 shown in Figure 2 is the outer ear. The most concave part near the center of the pinna 501 is called the concha, and the concha is located around the entrance of the ear canal 502.

[0015] The main body 11 is provided with a strain gauge 100, a control unit 200, a microphone 301, a filter 302, and an amplifier 303 shown in FIG. 4 . In the present disclosure, the strain gauge 100 is an example of a detector that detects air vibrations. The strain gauge 100 is attached to the main body 11 and connected to the control unit 200. A portion of the microphone 301 is exposed from the rear surface 11b of the main body 11 and collects sounds around the hearing aid 1. The control unit 200, the filter 302, and the amplifier 303 are built into the main body 11. Note that components other than those shown in FIG. 4 may be provided in the main body 11. For example, a battery that supplies power to the control unit 200 and other components may be provided inside the main body 11. Furthermore, components other than the strain gauge 100 may be provided in a separate unit rather than in the main body 11. Furthermore, the filter 302 and the amplifier 303 are not essential components of the hearing aid 1.

[0016] The ear hook part 12 has an overall curved shape and is a component that is hooked mainly around the back of the user's auricle 501 when the user wears the hearing aid 1. The ear hook part 12 connects the main body part 11 and the vibration unit 13. The ear hook part 12 is formed from, for example, a flexible resin, and houses a conductive wire that transmits an electrical signal from the main body part 11 to the vibration unit 13.

[0017] The vibration unit 13 includes a vibrator 304 shown in Fig. 4. The vibrator 304 vibrates based on an electrical signal that is based on an output signal from the microphone 301. Specifically, an electrical signal is input to the vibrator 304 from the main body 11 via the ear hook 12. When the electrical signal is input to the vibrator 304, the vibrator 304 converts the electrical signal into mechanical vibration, causing the vibration unit 13 to vibrate. For example, a piezoelectric element or the like can be used as the vibrator 304. Note that the vibrator 304 is attached to the vibration unit 13 so that when the hearing aid 1 is worn on the ear, the vibrator 304 vibrates in a direction toward or away from the temporal region of the head.

[0018] The vibration unit 13 is used by placing it against the temporal region of the user's head near the auricle 501. When the vibration unit 13 is placed against the temporal region, the vibrations of the vibration unit 13 are transmitted to the user's bones, such as the temporal bone, and then transmitted to the cochlea of ​​the user's inner ear by bone conduction. The vibrations transmitted to the cochlea of ​​the inner ear vibrate the auditory nerve, allowing the user to hear these vibrations as sound.

[0019] In this way, in the hearing aid 1, the vibrations of the vibrator 304 are transmitted to the bones of the user, so that the sound collected by the microphone 301 can be transmitted to the user by bone conduction.

[0020] The strain gauge 100 is provided on the contact surface 11a of the main body 11. When the user wears the hearing aid 1 in their ear, the strain gauge 100 can measure information about the inside or surrounding area of ​​the user's ear. When the user wears the hearing aid 1 in their ear and the vibration unit 13 vibrates, the vibrations of the vibration unit 13 are transmitted to the strain gauge 100 through the ear canal. The strain gauge 100 can measure the vibrations of the air inside the outer ear at this time.

[0021] The main body 11 may include one or more strain gauges 100. In the example shown in FIG. 3, multiple strain gauges are circumferentially arranged around the peripheral edge of the contact surface 11a of the main body 11. When multiple strain gauges 100 are provided, the strain gauges 100 may be arranged at equal intervals. This allows for even measurement of air vibrations in the ear canal, thereby enabling more accurate detection of vibrations. For example, the multiple strain gauges 100 may be arranged every 30 degrees, every 60 degrees, every 120 degrees, or another arrangement. In order to accurately measure information about the inside or surrounding area of ​​the user's ear, it is preferable to provide multiple strain gauges 100 on the contact surface 11a of the main body 11.

[0022] 4, the output of the strain gauge 100 is input to a control unit 200. The control unit 200 can include, for example, an analog front-end unit 201 and a signal processing unit 202. The electrodes 150 (described below) of the strain gauge 100 are connected to the analog front-end unit 201 of the control unit 200 using, for example, a flexible substrate, lead wires, or the like.

[0023] The analog front-end unit 201 includes, for example, a bridge circuit, an amplifier, an analog / digital conversion circuit (A / D conversion circuit), etc. The analog front-end unit 201 may include a temperature compensation circuit. The analog front-end unit 201 may be implemented as an IC or may be configured using individual components.

[0024] In the analog front-end unit 201, for example, a pair of electrodes 150 of the strain gauge 100 is connected to a bridge circuit. That is, one side of the bridge circuit is formed by the resistor 130 between the pair of electrodes 150, and the other three sides are formed by fixed resistors. This makes it possible to obtain a voltage (analog signal) corresponding to the resistance value of the resistor 130 as the output of the bridge circuit.

[0025] If the hearing aid 1 has multiple strain gauges 100, an input signal selection switch may be provided on the input side of the analog front end unit 201, and the input signal selection switch may be switched to input the output of each strain gauge 100 in turn to one analog front end unit 201. Alternatively, multiple analog front end units 201 may be provided, and the output of each strain gauge 100 may be input to a separate analog front end unit 201.

[0026] In the analog front-end unit 201, the voltage output from the bridge circuit is amplified by an amplifier, converted into a digital signal by an A / D conversion circuit, and sent to the signal processing unit 202. If the analog front-end unit 201 includes a temperature compensation circuit, the temperature-compensated digital signal is sent to the signal processing unit 202.

[0027] The signal processing unit 202 controls the frequency characteristics of the electrical signal transmitted from the main body 11 to the vibration unit 13, for example, based on the output of the strain gauge 100. The control unit 200 controls the frequency characteristics of the electrical signal transmitted from the main body 11 to the vibration unit 13, for example, by switching a filter circuit (described later) based on the output of the strain gauge 100. The signal processing unit 202 may include, for example, a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), main memory, etc. In this case, various functions of the signal processing unit 202 can be realized by reading a program recorded in the ROM or the like into the main memory and executing it by the CPU. However, part or all of the signal processing unit 202 may be realized solely by hardware. Furthermore, the signal processing unit 202 may be physically configured by multiple devices, etc.

[0028] In the hearing aid 1, the microphone 301 collects sounds around the main body 11. The output signal of the microphone 301 is input to the signal processing unit 202 of the control unit 200. The output signal of the microphone 301 is subjected to predetermined signal processing in the signal processing unit 202, and then input from the signal processing unit 202 to the filter 302. The predetermined signal processing is, for example, noise removal processing, attenuation processing, tone control processing, etc.

[0029] The filter 302 has multiple filter circuits that attenuate specific frequency components, and one of the multiple filter circuits is selected by the signal processing unit 202. Each of the multiple filter circuits is, for example, a notch filter. Each of the multiple filter circuits may be a band-pass filter, a low-pass filter, or a combination thereof. Each of the multiple filter circuits may be a filter that can change the frequency to be attenuated. The number of filter circuits is not particularly limited. It is also possible to bypass the filter circuits and input the output of the signal processing unit 202 directly to the amplifier 303. In this way, the signal processing unit 202 controls the frequency characteristics of the electrical signal by determining whether or not to pass through a filter circuit and which filter circuit to pass through.

[0030] The electrical signal input to filter 302 is input to amplifier 303 via a selected filter circuit or bypassing the filter circuit. Amplifier 303 amplifies the input electrical signal to a required level. The electrical signal amplified by amplifier 303 is transmitted to vibrator 304 of vibration unit 13. In this way, control unit 200 can perform signal processing on the output signal of microphone 301 to generate an electrical signal to be transmitted from main body 11 to vibration unit 13. The electrical signal input to vibrator 304 is converted into a mechanical signal by vibrator 304. That is, vibrator 304 vibrates in response to the input electrical signal, and this vibration vibrates vibration unit 13, which is transmitted to the user by bone conduction.

[0031] Here, the selection of a filter circuit will be described. Based on information sent from the analog front-end unit 201, the signal processing unit 202 can detect vibrations transmitted through the ear canal to the strain gauge 100. The signal processing unit 202 may have a function to detect feedback from these vibrations and reduce the feedback by selecting an appropriate filter. In other words, the hearing aid 1 may be a hearing aid with a feedback cancellation function. For example, the signal processing unit 202 measures the signal level for each frequency of vibrations inside the outer ear, and determines that feedback is occurring when the signal level of a specific frequency exceeds a predetermined threshold. In this case, the signal processing unit 202 selects a filter circuit that attenuates frequencies near the frequencies exceeding the predetermined threshold.

[0032] For example, the signal processing unit 202 measures the signal level for each frequency in the vibration transmitted through the ear canal to the strain gauge 100, and determines that no howling is occurring if the signal level of a specific frequency does not exceed a predetermined threshold. In this case, the output of the signal processing unit 202 is input directly to the amplifier 303, bypassing the filter circuit.

[0033] In this way, hearing aid 1 detects vibrations transmitted through the ear canal to strain gauge 100 based on the output of strain gauge 100, and signal processor 202 detects the occurrence of howling from the frequency and signal level of the vibrations inside the outer ear, and the frequency components that are the source of the howling are attenuated by filter 302. This makes it possible to suppress howling and improve the quality of the sound that the user hears through bone conduction.

[0034] The control unit 200 can, for example, compare the electrical signal input from the amplifier 303 to the vibrator 304 with the output of the strain gauge 100, and can use the amplifier 303 or other device to strengthen frequency bands with insufficient output before inputting them to the vibrator 304, or can use the amplifier 303 or other device to weaken unnecessary frequency bands that may cause noise before inputting them to the vibrator 304. This can improve the quality of the sound the user hears through bone conduction.

[0035] Furthermore, in the hearing aid 1, the strain gauge 100 is disposed on the contact surface 11a, where vibrations of the air in the user's ear canal are easily transmitted. This allows the strain gauge 100 to detect vibrations transmitted through the user's ear canal with high accuracy. If multiple strain gauges 100 are provided circumferentially around the periphery of the contact surface 11a of the main body 11, vibrations transmitted through the user's ear canal can be detected with even higher accuracy.

[0036] [Strain gauge 100] FIG. 5 is a plan view illustrating the strain gauge according to the first embodiment. FIG. 6 is a cross-sectional view (part 1) illustrating the strain gauge according to the first embodiment, showing a cross section along line AA in FIG. 5. Referring to FIGS. 5 and 6, the strain gauge 100 has a substrate 110, a resistor 130, wiring 140, electrodes 150, and a cover layer 160. For convenience, only the outer edge of the cover layer 160 is shown by a dashed line in FIG. 5. The cover layer 160 can be provided as needed.

[0037] In the explanation of the strain gauge 100 in FIGS. 5 and 6, for convenience, the side of the substrate 110 on which the resistor 130 is provided will be referred to as the "upper side," and the side on which the resistor 130 is not provided will be referred to as the "lower side." The upper surface of each part will be referred to as the "upper surface," and the lower surface of each part will be referred to as the "lower surface." However, the strain gauge 100 can also be used upside down. The strain gauge 100 can also be positioned at any angle. A planar view refers to viewing an object in a normal direction from above to below the upper surface 110a of the substrate 110. A planar shape refers to the shape of the object when viewed in the normal direction.

[0038] The substrate 110 is a member that serves as a base layer for forming the resistor 130 and the like. The substrate 110 is flexible. There are no particular limitations on the thickness of the substrate 110, and it may be determined appropriately depending on the intended use of the strain gauge 100, etc. For example, the thickness of the substrate 110 may be approximately 5 μm to 500 μm. From the standpoint of strain transmission from the outer surface of the main body 11 to the sensing part and dimensional stability against environmental changes, the thickness of the substrate 110 is preferably within the range of 5 μm to 200 μm. From the standpoint of insulation, the thickness of the substrate 110 is preferably 10 μm or more.

[0039] The substrate 110 is formed from an insulating resin film such as PI (polyimide) resin, epoxy resin, PEEK (polyether ether ketone) resin, PEN (polyethylene naphthalate) resin, PET (polyethylene terephthalate) resin, PPS (polyphenylene sulfide) resin, LCP (liquid crystal polymer) resin, polyolefin resin, etc. The film refers to a flexible member having a thickness of about 500 μm or less.

[0040] When the base material 110 is formed from an insulating resin film, the insulating resin film may contain fillers, impurities, etc. For example, the base material 110 may be formed from an insulating resin film containing fillers such as silica or alumina.

[0041] Examples of materials for the substrate 110 other than resin include crystalline materials such as SiO2, ZrO2 (including YSZ), Si, Si2N3, Al2O3 (including sapphire), ZnO, and perovskite ceramics (CaTiO3, BaTiO3). In addition to the crystalline materials described above, amorphous glass or the like may also be used as the material for the substrate 110. Metals such as aluminum, aluminum alloys (duralumin), and titanium may also be used as the material for the substrate 110. When a metal is used, an insulating film is provided on the metallic substrate 110.

[0042] The resistor 130 is a thin film formed in a predetermined pattern on the upper side of the substrate 110. In the strain gauge 100, the resistor 130 is a sensing part that receives strain and generates a resistance change. The resistor 130 may be formed directly on the upper surface 110a of the substrate 110, or may be formed on the upper surface 110a of the substrate 110 via another layer. For convenience, the resistor 130 is shown in FIG. 5 as having a dense matte pattern.

[0043] Resistor 130 has a structure in which multiple elongated portions are arranged at predetermined intervals with their longitudinal directions in the same direction (X direction in the example of FIG. 5), and the ends of adjacent elongated portions are alternately connected, resulting in a zigzag folded structure as a whole. The longitudinal direction of the multiple elongated portions is the grid direction, and the direction perpendicular to the grid direction is the grid width direction (Y direction in the example of FIG. 5).

[0044] In the resistor 130, the X- side end of the elongated portion located closest to the Y+ side bends in the Y+ direction and reaches one end 130e1 of the resistor 130 in the grid width direction. In addition, the X- side end of the elongated portion located closest to the Y- side bends in the Y- direction and reaches the other end 130e2 of the resistor 130 in the grid direction. Each of the ends 130e1 and 130e2 is electrically connected to the electrode 150 via the wiring 140. In other words, the wiring 140 electrically connects each of the ends 130e1 and 130e2 of the resistor 130 in the grid width direction to each of the electrodes 150.

[0045] The resistor 130 can be formed from, for example, a material containing Cr (chromium), a material containing Ni (nickel), or a material containing both Cr and Ni. That is, the resistor 130 can be formed from a material containing at least one of Cr and Ni. An example of a material containing Cr is a Cr mixed phase film. An example of a material containing Ni is Cu-Ni (copper-nickel). An example of a material containing both Cr and Ni is Ni-Cr (nickel-chromium).

[0046] Here, the Cr mixed phase film is a film in which Cr, CrN, Cr2N, etc. are mixed together. The Cr mixed phase film may contain inevitable impurities such as chromium oxide.

[0047] The thickness of the resistor 130 is not particularly limited and may be determined appropriately depending on the intended use of the strain gauge 100, etc. For example, the thickness of the resistor 130 may be approximately 0.05 μm to 2 μm. In particular, when the thickness of the resistor 130 is 0.1 μm or more, the crystallinity of the crystals constituting the resistor 130 (for example, the crystallinity of α-Cr) is improved. Furthermore, when the thickness of the resistor 130 is 1 μm or less, (i) cracks in the film and (ii) warping of the film from the substrate 110 caused by internal stress of the film constituting the resistor 130 are reduced.

[0048] Considering the need to prevent lateral sensitivity and to prevent disconnection, the width of resistor 130 is preferably 10 μm to 100 μm. Furthermore, the width of resistor 130 is preferably 10 μm to 70 μm, and more preferably 10 μm to 50 μm.

[0049] For example, when the resistor 130 is a Cr mixed-phase film, the stability of the gauge characteristics can be improved by using α-Cr (alpha chromium), which has a stable crystalline phase, as the main component. For example, when the resistor 130 is a Cr mixed-phase film, the resistor 130 can have an α-Cr main component, thereby enabling the gauge factor of the strain gauge 100 to be 10 or more, and the temperature coefficient of gauge factor (TCS) and the temperature coefficient of resistance (TCR) to be within the range of −1000 ppm / °C to +1000 ppm / °C. Here, the term “main component” refers to a component that accounts for 50% by weight or more of the total material constituting the resistor. From the viewpoint of improving the gauge characteristics, the resistor 130 preferably contains 80% by weight or more of α-Cr. Furthermore, from the same viewpoint, the resistor 130 more preferably contains 90% by weight or more of α-Cr. Note that α-Cr is Cr with a bcc structure (body-centered cubic lattice structure).

[0050] Furthermore, when the resistor 130 is a Cr mixed phase film, the Cr mixed phase film preferably contains 20 wt % or less of CrN and Cr2N. By containing 20 wt % or less of CrN and Cr2N in the Cr mixed phase film, a decrease in the gauge factor of the strain gauge 100 can be suppressed.

[0051] Furthermore, the ratio of CrN to Cr2N in the Cr mixed phase film is preferably 80 wt% or more but less than 90 wt% of the total weight of CrN and Cr2N. More preferably, the ratio is 90 wt% or more but less than 95 wt% of the total weight of CrN and Cr2N. Cr2N has semiconducting properties. Therefore, by setting the Cr2N ratio to 90 wt% or more but less than 95 wt%, the decrease in TCR (negative TCR) becomes more pronounced. Furthermore, by setting the Cr2N ratio to 90 wt% or more but less than 95 wt%, the ceramicization of the resistor 130 can be reduced. Therefore, the resistor 130 is less susceptible to brittle fracture.

[0052] On the other hand, CrN also has the advantage of being chemically stable. By including more CrN in the Cr mixed-phase film, the possibility of unstable N occurring can be reduced, resulting in a stable strain gauge. Here, "unstable N" refers to trace amounts of N2 or atomic N that can exist within the Cr mixed-phase film. This unstable N can escape from the film depending on the external environment (e.g., high-temperature environment). When unstable N escapes from the film, the film stress of the Cr mixed-phase film can change.

[0053] The wiring 140 is provided on the substrate 110. The wiring 140 is electrically connected to the resistor 130 and the electrode 150. The wiring 140 is not limited to being linear and can have any pattern. The wiring 140 can have any width and any length. For convenience, in FIG. 5, the wiring 140 is shown with a matte pattern that is less dense than the resistor 130.

[0054] The electrode 150 is disposed on the substrate 110. The electrode 150 is electrically connected to the resistor 130 via the wiring 140. In a plan view, the electrode 150 is formed in a generally rectangular shape, wider than the wiring 140. The electrodes 150 are a pair of electrodes for outputting a change in the resistance value of the resistor 130 caused by strain to the outside. For example, a lead wire or the like for external connection is joined to the electrode 150. The electrode 150 is connected to the analog front-end unit 201 of the control unit 200 via the lead wire or the like. A low-resistance metal layer such as copper or a metal layer with good solderability such as gold may be laminated on the upper surface of the electrode 150. Although the resistor 130, wiring 140, and electrode 150 are denoted by different reference numerals for convenience, they can be integrally formed from the same material in the same process. Note that in FIG. 5, the electrode 150 is depicted with a matte pattern of the same density as the wiring 140 for convenience.

[0055] The cover layer 160 is provided on the substrate 110 as needed. The cover layer 160 is provided on the upper surface 110a of the substrate 110 so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150. Examples of materials for the cover layer 160 include insulating resins such as PI resin, epoxy resin, PEEK resin, PEN resin, PET resin, PPS resin, and composite resins (e.g., silicone resin and polyolefin resin). The cover layer 160 may contain a filler or a pigment. The thickness of the cover layer 160 is not particularly limited and can be appropriately selected depending on the purpose. For example, the thickness of the cover layer 160 can be approximately 2 μm to 30 μm. The provision of the cover layer 160 can prevent mechanical damage to the resistor 130. The provision of the cover layer 160 can also protect the resistor 130 from moisture and the like.

[0056] In the strain gauge 100, when a Cr mixed-phase film is used as the material for the resistor 130, high sensitivity and miniaturization can be achieved. For example, while the output of a conventional strain gauge was approximately 0.04 mV / 2 V, an output of 0.3 mV / 2 V or more can be obtained when a Cr mixed-phase film is used as the material for the resistor 130. Furthermore, while the size (gauge length × gauge width) of a conventional strain gauge was approximately 3 mm × 3 mm, when a Cr mixed-phase film is used as the material for the resistor 130, the size (gauge length × gauge width) can be reduced to approximately 0.3 mm × 0.3 mm.

[0057] Therefore, the strain gauge 100 using the Cr mixed-phase film as the material for the resistor 130 is particularly suitable for use in a hearing aid 1 that needs to be placed in a narrow area of ​​the main body 11 and that needs to detect extremely minute internal pressure fluctuations that occur in the ear canal. Furthermore, the strain gauge 100 using the Cr mixed-phase film as the material for the resistor 130 has a higher resistance than conventional strain gauges. Therefore, the strain gauge 100 using the Cr mixed-phase film can be driven with less power than conventional strain gauges. Therefore, for example, if the strain gauge 100 is battery-powered, the battery life can be extended compared to conventional strain gauges.

[0058] [Strain gauge manufacturing method] The following describes a method for manufacturing the strain gauge 100. To manufacture the strain gauge 100, first, a substrate 110 is prepared, and a metal layer (for convenience, referred to as metal layer A) is formed on the upper surface 110a of the substrate 110. Metal layer A is a layer that will ultimately be patterned to become the resistor 130, wiring 140, and electrode 150. Therefore, the material and thickness of metal layer A are the same as the material and thickness of the resistor 130, wiring 140, and electrode 150 described above.

[0059] The metal layer A can be formed by, for example, magnetron sputtering using a target made of a raw material capable of forming the metal layer A. Instead of magnetron sputtering, the metal layer A may be formed by reactive sputtering, vapor deposition, arc ion plating, pulsed laser deposition, or the like.

[0060] Alternatively, a base layer may be formed on the upper surface 110a of the substrate 110 before the metal layer A is formed. For example, a functional layer having a predetermined thickness may be vacuum-deposited by conventional sputtering on the upper surface 110a of the substrate 110. By providing a base layer in this manner, the gauge characteristics of the strain gauge 100 can be stabilized.

[0061] In this application, the functional layer refers to a layer having the function of promoting the crystal growth of at least the upper layer, metal layer A (resistor 130). The functional layer preferably also has the function of preventing oxidation of metal layer A due to oxygen or moisture contained in the substrate 110 and / or the function of improving adhesion between the substrate 110 and metal layer A. The functional layer may also have other functions.

[0062] The insulating resin film constituting the substrate 110 may contain oxygen and moisture, and Cr may form a self-oxidized film. Therefore, when the metal layer A contains Cr, it is preferable to form a functional layer having a function of preventing oxidation of the metal layer A.

[0063] In this way, by providing a functional layer below the metal layer A, it is possible to promote crystal growth in the metal layer A, and to produce a metal layer A consisting of a stable crystalline phase. As a result, the stability of the gauge characteristics of the strain gauge 100 is improved. Furthermore, the material constituting the functional layer diffuses into the metal layer A, thereby improving the gauge characteristics of the strain gauge 100.

[0064] 7 is a cross-sectional view (part 2) illustrating the strain gauge according to the first embodiment. Fig. 7 shows the cross-sectional shape of the strain gauge 100 when a functional layer 120 is provided as an underlying layer for the resistor 130, the wiring 140, and the electrodes 150.

[0065] The planar shape of the functional layer 120 may be patterned to be substantially the same as the planar shapes of the resistor 130, the wiring 140, and the electrodes 150, for example. However, the planar shapes of the functional layer 120, the resistor 130, the wiring 140, and the electrodes 150 do not have to be substantially the same. For example, when the functional layer 120 is formed from an insulating material, the functional layer 120 may be patterned to be different from the planar shapes of the resistor 130, the wiring 140, and the electrodes 150. In this case, the functional layer 120 may be formed in a solid shape in the region where the resistor 130, the wiring 140, and the electrodes 150 are formed, for example. Alternatively, the functional layer 120 may be formed in a solid shape over the entire upper surface of the substrate 110.

[0066] Next, the metal layer A is patterned by photolithography to form the resistor 130, two wires 140, and two electrodes 150, each having a planar shape as shown in FIG.

[0067] After forming the resistor 130, the wiring 140, and the electrodes 150, a cover layer 160 may be formed on the upper surface 110a of the substrate 110. The cover layer 160 covers the resistor 130 and the wiring 140, but the electrodes 150 may be exposed from the cover layer 160. For example, the cover layer 160 can be formed by laminating a semi-cured thermosetting insulating resin film on the upper surface 110a of the substrate 110 so as to cover the resistor 130 and the wiring 140 and expose the electrodes 150, and then heating and curing the insulating resin film. Through the above steps, the strain gauge 100 is completed.

[0068] Second Embodiment In the second embodiment, a pulse wave detector is shown as an example of a wearable device worn on the ear of a user. Note that in the second embodiment, descriptions of components that are the same as those in the embodiments already described may be omitted.

[0069] Fig. 8 is a side view illustrating a pulse wave detector according to a second embodiment, Fig. 9 is a cross-sectional view illustrating a pulse wave detector according to a second embodiment, and Fig. 10 is a block diagram illustrating the configuration of a pulse wave detector according to a second embodiment.

[0070] The pulse wave detector 2 shown in FIGS. 8 to 10 includes a main body 31, an earpiece 32, a cable 33, and a strain gauge 100. As shown in FIGS. 8 and 9, the pulse wave detector 2 has a shape similar to that of a so-called canal-type earphone. The method of wearing the pulse wave detector 2 is similar to that of a canal-type earphone. That is, the pulse wave detector 2 is worn in the user's ear with the earpiece 32 inserted into the ear canal. Note that the cable 33 is not shown in FIG. 9. Note that in this embodiment, the pulse wave detector 2 also functions as a regular earphone for listening to music, etc. However, the pulse wave detector 2 does not necessarily have to function as an earphone.

[0071] The pulse wave detector 2 may be a pulse wave detector for one ear consisting of a single pulse wave detector 2 as shown in Fig. 8, or a pulse wave detector for both ears having two pulse wave detectors 2 as shown in Fig. 8. When the pulse wave detector 2 is for both ears, the pulse wave detector for the right ear and the pulse wave detector for the left ear may each have the same configuration.

[0072] The main body 31 is a hollow member made of, for example, resin. The main body 31 is provided with a pulse wave detection unit 401, a storage unit 402, an amplifier 403, and a speaker 404, as shown in FIG. 10. The main body 31 may be provided with components other than those shown in FIG. 10. For example, a battery may be provided inside the main body 31 to supply power to the strain gauge 100, the pulse wave detection unit 401, etc. Furthermore, if the pulse wave detector 2 does not have the function of an earphone, the speaker 404 is not an essential component.

[0073] The earpiece 32 is attached to the main body 31. The earpiece 32 is a component that is inserted into the user's ear canal. The earpiece 32 is also replaceable, and for example, multiple types of earpieces 32 with different shapes and sizes may be prepared in advance. This allows the user of the pulse wave detector 2 to replace the earpiece 32 to fit the shape of their own ear. The earpiece 32 may be made of an elastic material such as silicone rubber.

[0074] 9, earpiece 32 has opening 32x. Also, diaphragm 180 that closes one end of opening 32x of earpiece 32 is provided inside main body 31. On the surface of diaphragm 180 that is not exposed to opening 32x, strain gauge 100 is mounted to measure vibrations of air inside the user's outer ear as internal pressure fluctuations generated in the ear canal.

[0075] Diaphragm 180 may be equipped with one strain gauge 100 or may be equipped with multiple strain gauges 100. Diaphragm 180 is disposed, for example, inside main body 31, but a part or all of diaphragm 180 may be disposed inside earpiece 32. Note that since there is space around strain gauge 100, diaphragm 180 and strain gauge 100 can deform freely.

[0076] Fluctuations in the internal pressure of the ear canal reflect jugular venous fluctuations or right ventricular hemodynamics. In other words, because fluctuations in the internal pressure of the ear canal correlate with a pulse wave signal linked to blood pressure, a pulse wave signal can be detected from the fluctuations in the internal pressure of the ear canal. When the earpiece 32 of the pulse wave detector 2 is placed in the ear canal of the user, the fluctuations in the internal pressure of the ear canal are transmitted to the strain gauge 100 mounted on the diaphragm 180 via the opening 32x.

[0077] The diaphragm 180 can be made of a semiconductor such as silicon that deforms in response to changes in internal pressure occurring in the ear canal. When the diaphragm 180 deforms in response to changes in internal pressure occurring in the ear canal, the resistance value of the resistor 130 of the strain gauge 100 changes.

[0078] 10, the output of strain gauge 100 is input to pulse wave detection unit 401. Pulse wave detection unit 401 detects the pulse wave of the user based on the internal pressure fluctuation occurring in the user's ear canal, which is indicated by the measurement result of strain gauge 100.

[0079] Specifically, electrodes 150 of strain gauge 100 are connected to a bridge circuit included in pulse wave detection unit 401, and an analog pulse wave signal, which is a periodic voltage change corresponding to the resistance value of resistor 130, can be obtained as an output of the bridge circuit. In pulse wave detection unit 401, the analog pulse wave signal is A / D converted and subjected to signal processing such as noise removal before being stored in storage unit 402. Storage unit 402 is, for example, a non-volatile memory such as a flash memory.

[0080] In pulse wave detector 2, diaphragm 180 is disposed in the area exposed within opening 32x of earpiece 32, so that when earpiece 32 is placed in the ear canal of the user, a sealed space can be formed between the user's eardrum and diaphragm 180. As a result, internal pressure fluctuations occurring in the ear canal can be detected with high accuracy by strain gauge 100.

[0081] If the diaphragm 180 is equipped with multiple strain gauges 100, the pulse wave detection unit 401 may use the average or maximum resistance value of each resistor 130 as the pulse wave signal, or some other value. The pulse wave signal may be the result of performing an appropriate calculation on the outputs of the multiple strain gauges 100. If the pulse wave detector 2 is a bilateral pulse wave detector, the pulse wave signal may be generated by combining the measurement results of the strain gauge 100 on the right ear and the measurement results of the strain gauge 100 on the left ear. For example, the pulse wave detector 2 may use the average of the measurement results of the strain gauge 100 on the right ear and the measurement results of the strain gauge 100 on the left ear, or the maximum value of these measurement results, as the pulse wave signal.

[0082] The pulse wave detector 2 can also be used as an earphone capable of hearing sound. When the pulse wave detector 2 is used as an earphone, an electrical signal representing sound is input via a wired or wireless connection from another device to the amplifier 403 shown in FIG. 10 . The amplifier 403 drives the speaker 404 in response to the input electrical signal, which then converts the electrical signal into sound and outputs it to the user's ear canal through the opening 32x of the earpiece 32. The amplifier 403 may also have functions such as noise reduction, attenuation, and tone control. When the pulse wave detector 2 functions as an earphone, it is desirable to perform pulse wave detection when no sound is being output. Furthermore, as described above, when the pulse wave detector 2 is electrically connected to another device, the pulse wave detector 2 may not have a built-in battery, and power may be supplied to the pulse wave detector 2 from the other device.

[0083] In this way, pulse wave detector 2 can detect pulse wave signals easily and anywhere without interfering with the freedom of the human body, making it possible to record and analyze pulse wave signals over long periods of time, and easily detect various vital signs that cannot be obtained through short-term measurements.

[0084] Furthermore, by incorporating amplifier 403 and speaker 404 inside main body 31, pulse wave detector 2 can also be used as a regular earphone when not detecting pulse waves. In other words, pulse wave detector 2 can be used to listen to music, etc., in addition to detecting pulse wave signals.

[0085] Third Embodiment In the above-described embodiments and their modified examples, examples have been described in which the detection unit according to the present disclosure is a strain gauge using a resistor. That is, in the above-described embodiments, examples have been described in which the detection unit according to the present disclosure is an electrical resistance type metal strain gauge. However, the detection unit according to the present disclosure is not limited to a metal strain gauge. For example, the detection unit according to the present disclosure may be a strain gauge that detects magnetic changes caused by strain in a strain-generating body (or a structure equivalent to a strain-generating body) using a detection element included in the strain gauge.

[0086] Specifically, the detection unit according to the present disclosure may be a strain gauge including a detection element that utilizes the Villari phenomenon (described later). The detection unit according to the present disclosure may also be a strain gauge including a detection element having a magnetic tunnel junction (described later) structure. Hereinafter, in a third embodiment, a strain gauge including a detection element that utilizes the Villari phenomenon will be described. In a fourth embodiment, a strain gauge including a detection element having a magnetic tunnel junction structure will be described.

[0087] In each embodiment of this specification, components having similar functions are given similar names and numbers, and descriptions thereof will not be repeated. Furthermore, the directions of the x-axis, y-axis, and z-axis are the same in each drawing (drawings from FIG. 11 onward) relating to each embodiment that follows. Furthermore, in the following description, the positive direction of the z-axis will be referred to as "upper," and the negative direction of the z-axis will be referred to as "lower." That is, in the following description, "upper side" refers to the positive side of the z-axis, and "upper surface" refers to the surface on the positive side of the z-axis. Furthermore, "lower side" refers to the negative side of the z-axis, and "lower surface" refers to the surface on the negative side of the z-axis.

[0088] FIG. 11 is a diagram illustrating an example of a detection element 300 included in a strain gauge according to the third embodiment. FIG. 11(a) is a plan view of the detection element 300 when viewed from the positive to the negative direction of the z-axis (i.e., from the top to the bottom). FIG. 11(b) is a cross-sectional view of the detection element 300 shown in FIG. 11(a) taken along line α-α'. Note that FIGS. 11(a) and 11(b) do not illustrate wiring extending from the detection element 300. However, the detection element 300 may be connected to wiring that connects a drive coil 320 (described later) to a power source and wiring that transmits a current detected by a sensing coil 380.

[0089] As shown in FIG. 11(a), the detection element 300 includes a drive coil 320, a sense coil 380, and a base layer 310. The base layer 310 is a layer that serves as the core of the drive coil 320 and the sense coil 380. The sense coil 380 is a coil that detects the strength of magnetization of the base layer 310 (more precisely, the base metal 370 described below). The drive coil 320 is a coil that generates a magnetic field. The detection element 300 has a double structure in which the sense coil 380 is wound on the inside and the drive coil 320 is wound on the outside, with the base layer 310 as the core. Note that the materials for the drive coil 320 and the sense coil 380 are preferably conductive metals such as Cu, Ag, Al, and Au, or alloys of these metals. The number of turns and cross-sectional area of ​​the drive coil 320 and the sense coil 380 may be appropriately designed depending on the vibration (i.e., weak stress) detection sensitivity required of the detection element 300.

[0090] As will be described in detail later, when stress is applied to the base layer 310, the strength of magnetization changes in a base metal 370 (described later) included in the base layer 310. The detection element 300 can determine the strength of the stress (i.e., the degree of strain) applied to the base layer 310 by detecting this change in the strength of magnetization with the sensing coil 380.

[0091] The configuration of the detection element 300 will be further described with reference to the cross-sectional view of Figure 11(b). In Figure 11(b), the drive coil 320, the sensing coil 380, and the three insulating layers 340, 350, and 360 are each formed to surround the base metal 370, which is the core material. In other words, layers with the same component number in Figure 11(b) are connected to surround the base metal 370.

[0092] The base metal 370 is a member that serves as the core material for the various coils and insulating layers. The base metal 370 may be, for example, a substantially flat metal plate. The base metal 370 is covered and surrounded by the insulating layer 360. The base metal 370 is preferably made of a soft magnetic material, such as an Fe-Si-Al alloy such as sendust, or an Ni-Fe alloy such as permalloy. As shown in FIG. 11(b), the aforementioned base layer 310 is made of this base metal 370 and the insulating layer 360.

[0093] An insulating layer 350 is formed on the outside of insulating layer 360 so as to surround insulating layer 360. An insulating layer 340 is further formed on the outside of insulating layer 350. Insulating layer 350 is a layer that includes sensing coil 380, and is a layer in which gaps between sensing coil 380 are filled with an insulating material. Insulating layer 340 is a layer that includes drive coil 320, and is a layer in which gaps between drive coil 320 are filled with an insulating material. Insulating layers 340, 350, and 360 are preferably made of a dry film that is not affected by the magnetic field or a cured resist such as photosensitive polyimide.

[0094] As shown in FIG. 11(b), one surface of the detection element 300 may be attached to a substrate 110. The substrate 110 is a member that fixes the detection element 300. For example, the substrate 110 may be a flexible substrate made of a plastic film or the like. The detection element 300 is attached to the main body 11 or the diaphragm 180 via the substrate 110. The detection element 300 may be a detection element that is flat or thin film-shaped as a whole. If the detection element 300 is flat or thin film-shaped, the detection element 300 can be more easily attached to the substrate 110. The substrate 110 is not an essential component of the detection element 300. For example, the detection element 300 may be used without the substrate 110, with the lower surface of the detection element 300 directly attached to the main body 11 or the diaphragm 180.

[0095] The main body 11 or the diaphragm 180 according to this embodiment may basically have the same configuration and material as the main body 11 according to the first embodiment or the diaphragm 180 according to the second embodiment. However, in this embodiment, it is more preferable that the main body 11 and the diaphragm 180 are made of a non-magnetic material. The main body 11 and the diaphragm 180 according to this embodiment can be made of, for example, non-magnetic stainless steel.

[0096] Next, the principle of detecting strain using the detection element 300 will be outlined. The detection element 300 includes a base metal 370, which is a magnetic material. When an alternating current is supplied from a power source to the drive coil 320, the drive coil 320 generates an alternating magnetic field around it. This generates a magnetic field, and the base metal 370 is magnetized. When vibrations from the ear canal are transmitted to the detection element 300 in this state, the base metal 370 of the detection element 300 is subjected to a slight stress. Furthermore, if vibrations cause minute deformation (i.e., strain in the member) in which the detection element 300 is attached (the main body 11 in the first embodiment, or the diaphragm 180 in the second embodiment), the strain is transmitted through the substrate 110, and in this case too, stress is applied to the base metal 370. When the detection element 300 is attached without the substrate 110, stress is transmitted directly from the attached member to the base metal 370 (and the insulating layers 340 to 360 covering it).

[0097] When stress is applied to the base metal 370, the magnetic permeability of the base metal 370 changes in response to the stress. Therefore, the magnetization strength (degree of magnetization) of the base metal 370 changes. This phenomenon, in which the magnetic permeability and magnetization strength of a magnetic material change when stress is applied to the magnetic material, is called the "Villari phenomenon." According to the configuration of the detection element 300, an AC voltage corresponding to the magnetization strength of the base metal 370 is induced in the sensing coil 380, which serves as a pickup coil. Based on the principle of the Villari phenomenon, the stress applied to the base metal 370 can be calculated from the value of this AC voltage. Vibrations transmitted to the detection element 300 through the ear canal can then be detected from the calculated change in stress. When the detection element 300 has the shape shown in FIGS. 11(a) and 11(b), the grid direction of the detection element 300 is the same as the α-α' direction in FIG. 11(a). Based on the principle described above, the sensing element 300 can detect vibrations transmitted through the ear canal to the sensing element 300. In other words, the sensing element 300 functions as a strain gauge sensing element.

[0098] It is desirable that the drive coil 320 be wound as uniformly as possible around the outside of the sensing coil 380 and over the entire area where the sensing coil 380 is present. This allows an alternating magnetic field to be applied more uniformly to the entire area of ​​the base metal 370 where the sensing coil 380 is present. This allows for more precise detection of changes in the magnetization strength of the base metal 370 due to the Villari phenomenon. This improves the performance of the detection element 300.

[0099] Furthermore, insulating layer 360 may be formed on only part of base metal 370 rather than the entirety of base metal 370. For example, a configuration may be adopted in which the regions of base metal 370 where sensing coil 380 and drive coil 320 are wound are covered with insulating layer 360, insulating layer 350 including sensing coil 380 is then covered from above insulating layer 360, and insulating layer 340 including drive coil 320 is further covered from above insulating layer 350.

[0100] 11(b), both ends of the base metal 370 in the x direction do not have to be covered with the insulating layer 360.

[0101] In the wearable device according to this embodiment, when the main body 11 or the diaphragm 180 is deformed (i.e., strain occurs in the strain element), and / or when vibration from the ear canal is transmitted directly to the strain gauge itself, the substrate 110 of the strain gauge (or the detection element 300 itself) is strained. The detection element 300 can detect the magnetic change caused by this strain based on the principle of the Villari phenomenon described above.

[0102] A strain gauge including the detection element 300 according to this embodiment can be arranged on the main body 11 and the diaphragm 180 in any of the arrangement patterns shown in the first and second embodiments and their modified examples. That is, the detection element 300 according to this embodiment can be used to detect vibrations transmitted to the detection element 300 through the ear canal, just as when an electrical resistance type strain gauge is used. Therefore, the strain gauge according to this embodiment has the same effects as the strain gauge 100 according to the first and second embodiments and their modified examples.

[0103] Fourth Embodiment FIG. 12 is a diagram showing a detection element 500, which is an example of a detection element included in a strain gauge according to the fourth embodiment. FIG. 13 is a diagram showing a detection element 600, which is another example of a detection element according to the fourth embodiment. FIG. 14 is a diagram showing a detection element 700, which is yet another example of a detection element according to the fourth embodiment. (a) of FIGS. 12 to 14 are perspective views of the detection elements 500, 600, and 700, respectively. (b) of FIGS. 12 to 14 are plan views of the detection elements 500, 600, and 700, respectively, when viewed from the positive direction to the negative direction of the z axis. (c) of FIGS. 12 to 14 are cross-sectional views of the detection elements 500, 600, and 700, taken along a plane parallel to the zx plane. Note that wiring extending from the detection elements is not shown in any of FIGS. 12 to 14. However, these detection elements 500, 600, and 700 may be connected to a wiring that connects the upstream electrode 510 to a power source, and a wiring that connects the downstream electrode 520 to a power source, which will be described later.

[0104] 12 to 14(a), the detection elements 500, 600, and 700 include an upstream electrode 510, a downstream electrode 520, a magnetic film 530, and an insulating film 540. As shown in the figures, the insulating film 540 is sandwiched between the magnetic films 530. A magnetic tunnel junction is formed by the magnetic film 530 and the insulating film 540. In other words, the detection elements 500, 600, and 700 have a structure in which electrodes are connected to a magnetic tunnel junction structure.

[0105] The lower surfaces of the detection elements 500, 600, and 700 may be attached to a substrate similar to the substrate 110 according to the first and second embodiments. The detection element 500 may then be attached to the main body 11 or the diaphragm 180 via the substrate. The detection elements 500, 600, and 700 may be flat-plate or thin-film detection elements as a whole. When the detection elements 500, 600, and 700 are flat-plate or thin-film, the detection elements 500, 600, and 700 can be more easily attached to the substrate, the main body 11, or the diaphragm 180. For example, the lower surfaces of the detection elements 500, 600, and 700 may be directly attached to the main body 11 or the diaphragm 180.

[0106] The magnetic film 530 is a magnetic nano-thin film. The insulating film 540 is a nano-thin film made of an insulator. There are no particular limitations on the materials for the magnetic film 530 and the insulating film 540, as long as a magnetic tunnel junction structure can be formed. For example, the magnetic film 530 can be made of cobalt-iron-boron, or a 3d transition metal ferromagnetic material such as Fe, Co, or Ni, or an alloy containing any of these. The insulating film 540 can be made of silicon oxide, silicon nitride, aluminum oxide, magnesium oxide, or the like.

[0107] The upstream electrode 510 and the downstream electrode 520 are electrodes for applying a voltage to the magnetic tunnel junction structure. In the examples of FIGS. 12 to 14, a current flows from the upstream electrode 510 to the downstream electrode 520. For example, in the case of FIG. 12(c), when a voltage is applied between the upstream electrode 510 and the downstream electrode 520, electrons flow from the upper magnetic film 530 (positive z-axis direction side) across the insulating film 540 to the lower magnetic film 530 (negative z-axis direction side). This is a phenomenon called the "tunnel effect," and the electrical resistance when electrons pass through the insulating film 540 is called "tunnel resistance." In the examples of FIGS. 12 to 14, the junctions of the electrodes have ends processed to prevent current from short-circuiting the magnetic tunnel junction structure.

[0108] When vibrations from within the ear canal are applied to the sensing element 500 via the substrate 110 or the like, the sensing element 500 is slightly distorted. This distortion of the sensing element 500 causes a magnetic change in the tunnel junction structure of the sensing element 500. More specifically, the magnetization directions of the upper and lower magnetic films 530 are misaligned. When the magnetization directions of the upper and lower magnetic films 530 are misaligned in this way, the tunnel resistance increases compared to when the magnetization directions are parallel (tunnel magnetoresistance effect). Therefore, in the sensing element 500 having the above-described configuration, the current flowing between the electrodes decreases depending on the magnitude of distortion in the sensing element 500 (more precisely, the magnetic tunnel junction portion). In other words, as the distortion increases, the electrical resistance increases. In this way, the sensing element 500 can detect its own distortion based on the current value relative to the applied voltage. In other words, the sensing element 500 can detect vibrations transmitted to itself. Therefore, by attaching the detection element 500 to the main body 11 or the diaphragm 180, vibrations of the air inside the ear canal that are transmitted to the detection element 300 can be detected.

[0109] The detection element having a magnetic tunnel junction structure is not limited to the example shown in FIG. 12. For example, detection elements 600 and 700 shown in FIGS. 13 and 14 can also be used. Both the detection element 600 shown in FIG. 13 and the detection element 700 shown in FIG. 14 are configured with an upstream electrode 510, a downstream electrode 520, a magnetic film 530, and an insulating film 540, and the principle of detecting strain using this configuration is similar to that of the detection element 500. The basic operation of the detection elements 600 and 700 is also similar to that of the detection element 500. The grid directions of the detection elements 500, 600, and 700 correspond to the x-axis direction (the positive direction of the x-axis and the negative direction of the x-axis) in FIGS. 12 to 14, respectively. As shown in the figure, the detection element 600 shown in FIG. 13 has a structure in which the upper magnetic film 530 and the lower magnetic film 530 are partially connected. That is, a magnetic tunnel junction structure is formed only in a partial region of the magnetic film 530, and the tunnel magnetoresistance effect occurs in this structure. On the other hand, the detection element 700 shown in Fig. 14 is attached to the base material 110 via a substrate 710. As shown in Figs. 12 to 14, the design of the detection element may be changed as appropriate depending on the required size, durability, magnitude of stress to be detected, and the like, as long as it does not deviate from the above-mentioned principle.

[0110] The main body 11 and diaphragm 180 according to this embodiment may have essentially the same configuration and material as those according to the first embodiment. However, in this embodiment, it is more preferable that the main body 11 and diaphragm 180 be made of a nonmagnetic material. The main body 11 and diaphragm 180 according to this embodiment may be made of, for example, nonmagnetic stainless steel. The entire sensing element 500, 600, and 700 may have a substantially flat, film-like shape, for example. This allows the sensing element 500 to be easily attached to the main body 11 and diaphragm 180. The sensing elements 500, 600, and 700 may also have a structure for applying a weak magnetic field to the structural components of the magnetic tunnel junction, such as the drive coil. Applying a magnetic field to the structural components of the magnetic tunnel junction allows for more stable measurement of the tunnel magnetoresistance effect, thereby enabling stable strain detection.

[0111] Furthermore, the terms "upstream electrode" and "downstream electrode" in detection elements 500, 600, and 700 are used for convenience, and the direction of current flow may be reversed. That is, detection elements 500, 600, and 700 shown in Figures 12 to 14 may be designed so that current flows from downstream electrode 520 to upstream electrode 510.

[0112] In the wearable device according to this embodiment, when vibrations from the ear canal are applied to the strain gauge, the substrate of the strain gauge (or the sensing element 500, 600, or 700 itself) is strained. The sensing element 500, 600, or 700 can detect the magnetic change caused by this strain based on the principle of the tunneling magnetoresistance effect described above.

[0113] The strain gauges including the detection elements 500, 600, and 700 according to the present embodiment can be arranged on the main body 11 and the diaphragm 180 in any of the arrangement positions shown in the first and second embodiments and their modified examples. That is, the detection elements 500, 600, and 700 according to the present embodiment can be used to detect strain in the main body 11 and the diaphragm 180 in the same way as when an electrical resistance type strain gauge is used. Therefore, the strain gauge according to the present embodiment has the same effects as the strain gauge 100 according to the first and second embodiments and their modified examples.

[0114] Fifth Embodiment The detection unit according to the present disclosure may be a semiconductor strain gauge, a capacitance pressure sensor, or an optical fiber strain gauge. The detection unit according to the present disclosure may also be a mechanical pressure sensor, a vibration pressure sensor, or a piezoelectric pressure sensor. The principles of various strain gauges and pressure sensors are described below.

[0115] (Semiconductor strain gauge) A semiconductor strain gauge is a strain gauge that detects strain by utilizing the piezoresistive effect of a semiconductor. In other words, a semiconductor strain gauge is a strain gauge that uses a semiconductor as the strain detection element.

[0116] It is known that when stress is applied to a semiconductor, strain occurs in the semiconductor's crystal lattice, changing the number and mobility of carriers in the semiconductor, resulting in a change in electrical resistance. Like electrical resistance metal strain gauges, semiconductor strain gauges can be used by being directly attached to the main body 11 or the diaphragm 180. In this case, when the main body 11 or the diaphragm 180 expands or contracts due to vibrations of the air inside the ear canal, the attached semiconductor (more specifically, the semiconductor's crystal lattice) is strained, changing the electrical resistance. Therefore, the amount of strain in the main body 11 or the diaphragm 180 can be determined by measuring this electrical resistance.

[0117] Semiconductor strain gauges can also be configured as strain sensors with a diaphragm structure. In this case, the strain sensor includes, for example, a non-metallic diaphragm (or a metal diaphragm with an electrically insulating layer formed on it) and a semiconductor (e.g., a silicon thin-film semiconductor) formed on the diaphragm. In such a structure including a diaphragm, when stress is applied to the diaphragm due to vibrations of the air inside the ear canal, the diaphragm distorts, causing a change in the electrical resistance of the semiconductor. Therefore, the amount of strain of the diaphragm can be determined by measuring this electrical resistance. From the change in the amount of strain of the diaphragm, the period and magnitude of the vibration transmitted to the diaphragm can be determined. Therefore, semiconductor strain gauges can be used to detect air vibrations inside the ear canal.

[0118] (Capacitive pressure sensor) A capacitance-type pressure sensor is a pressure sensor that measures the pressure applied to a diaphragm as a change in the capacitance of a pair of electrodes. That is, a capacitance-type pressure sensor is a pressure sensor that uses a pair of electrodes as a detection element. A capacitance-type pressure sensor includes, for example, a diaphragm as a movable electrode and one or more fixed electrodes. The diaphragm is formed, for example, from silicon containing impurities (i.e., silicon that functions as a conductor).

[0119] When pressure (e.g., pressure due to air vibrations inside the ear canal) is applied to the diaphragm, the diaphragm is displaced, causing a change in the distance between the fixed electrode and the movable electrode. It is known that the capacitance between the electrodes is determined according to the distance between the electrodes, provided that the dielectric constant of the inter-electrode medium and the area of ​​the electrodes are constant. Therefore, by measuring the capacitance, the amount of diaphragm displacement (i.e., the magnitude of the pressure) can be determined. Therefore, the vibration of the air inside the ear canal can be detected using a capacitance-type pressure sensor.

[0120] (Optical fiber strain gauge) An optical fiber strain gauge is a strain gauge that detects strain using an optical fiber with a fiber Bragg grating (FBG) formed on it. In other words, an optical fiber strain gauge is a strain gauge that uses an optical fiber as the strain detection element. The FBG is a diffraction grating that reflects light differently from the rest of the optical fiber, and each of these gratings is formed at a regular interval. When the optical fiber is strained and stretched, the FBG grating spacing widens, causing a change in the wavelength of the reflected light of light (e.g., laser light) incident on the optical fiber. Conversely, when the optical fiber is strained and contracted, the FBG grating spacing narrows, causing a change in the wavelength of the reflected light of light (e.g., laser light) incident on the fiber.

[0121] An optical fiber having such characteristics is attached to the main body 11 or the diaphragm 180, and the amount of strain in the optical fiber (i.e., the vibration received by the optical fiber) can be detected by measuring the wavelength spectrum of the reflected light from the optical fiber. Note that the optical fiber strain gauge may be a strain gauge that identifies the amount of strain in the optical fiber from changes in the frequency of Brillouin scattered light generated within the optical fiber.

[0122] (mechanical pressure sensor) A mechanical pressure sensor is a sensor that measures the amount of displacement of a mechanical structure to determine the pressure acting on the structure. A mechanical pressure sensor includes, for example, a spring or a bent tube, and measures the amount of expansion and contraction of the spring or the bent tube. These amounts of expansion and contraction (i.e., the amount of displacement) change depending on the magnitude of the pressure acting on the spring or the bent tube. Therefore, by measuring the amount of expansion and contraction, it is possible to detect the pressure acting on the spring or the bent tube (for example, pressure due to vibration of air inside the ear canal). The shape and size of the spring or the bent tube may be determined appropriately depending on the size and shape of the object to which the mechanical pressure sensor is attached.

[0123] (resonant pressure sensor) A resonant pressure sensor is a sensor that detects pressure by utilizing the phenomenon in which the natural frequency of an elastic beam changes depending on the pressure (i.e., axial force) generated along the axis of the elastic beam. Similar to an electrical resistance metal strain gauge, a resonant pressure sensor can be used by being directly attached to the main body 11 and the diaphragm 180. Alternatively, for example, the resonant pressure sensor may be a pressure sensor composed of a diaphragm formed on a substrate and a beam-shaped vibrator formed on the surface of the diaphragm.

[0124] In either case, when the main body 11 or the diaphragm 180 is distorted, the pressure is transmitted directly or indirectly to the vibrator, generating an axial force in the vibrator. The natural frequency of the vibrator changes depending on the axial force. Therefore, by measuring the natural frequency of the vibrator, the magnitude of the pressure on the main body 11 or the diaphragm 180 can be determined.

[0125] (Piezoelectric pressure sensor) A piezoelectric pressure sensor is a sensor that contains a piezoelectric element (also called a piezo element) and detects pressure using the characteristics of this piezoelectric element. When a force is applied to a piezoelectric element and it deforms (strains), it generates an electromotive force corresponding to that force. When a voltage is applied to a piezoelectric element, it also has the characteristic of expanding and contracting, generating a force corresponding to that voltage.

[0126] The piezoelectric pressure sensor can determine the force applied to the piezoelectric element (i.e., the amount of strain of the piezoelectric element) by measuring the electromotive force of the piezoelectric element. Therefore, by attaching the piezoelectric pressure sensor to the main body 11 or the diaphragm 180, it is possible to detect the strain generated in the piezoelectric element due to the vibration of air inside the ear canal. In other words, the piezoelectric pressure sensor can detect the vibration of air inside the ear canal.

[0127] As explained above, even when a semiconductor strain gauge, a capacitance pressure sensor, an optical fiber strain gauge, a mechanical pressure sensor, a vibration pressure sensor, or a piezoelectric pressure sensor is used, the same effects as those of the strain gauge 100 according to the first and second embodiments and their modified examples can be obtained.

[0128] The above describes preferred embodiments and the like. However, the wearable device according to the present disclosure is not limited to the above-described embodiments and modifications. For example, various modifications and substitutions can be made to the wearable device according to the above-described embodiments and the like without departing from the scope of the claims. [Explanation of symbols]

[0129] 1 hearing aid, 2 pulse wave detector, 11, 31 main body, 11a contact surface, 11b back surface, 12 ear hook portion, 13 vibration unit, 32 earpiece, 32x opening, 33 cable, 100 strain gauge, 110 substrate, 110a upper surface, 120 functional layer, 130 resistor, 130e1, 130e2 termination, 140 wiring, 150 electrode, 160 cover layer, 180 diaphragm, 200 control unit, 201 analog front end unit, 202 signal processing unit, 301 microphone, 302 filter, 303, 403 amplifier, 304 vibrator, 401 pulse wave detection unit, 402 memory unit, 404 speaker, 300, 500, 600, 700 detection element, 310 Base layer, 320, drive coil, 340, 350, 360, insulating layer, 370, base metal, 380, sensing coil, 510, upstream electrode, 520, downstream electrode, 530, magnetic film, 540, insulating film, 710, substrate

Claims

1. A wearable device worn on a user's ear, a microphone for collecting sounds around the wearable device; a vibrator that contacts the side of the user's head when the wearable device is worn and vibrates in response to an electrical signal based on an output signal from the microphone; a main body portion that is abutted against or inserted into the entrance of the ear canal when the wearable device is worn; A wearable device in which a strain gauge is provided on one surface of the main body that abuts the entrance of the ear canal or on one surface facing the direction in which the ear canal extends, to measure vibrations of air inside the ear canal.

2. the wearable device is a hearing aid, The wearable device according to claim 1 , wherein the vibrator transmits the vibration to the user's bones, thereby transmitting the sound collected by the microphone to the user by bone conduction.

3. The wearable device according to claim 1 or 2, wherein a plurality of strain gauges are provided circumferentially around the edge of the one surface.

4. The wearable device according to claim 1 , further comprising a signal processing unit that controls frequency characteristics of the electrical signal based on an output of the strain gauge.

5. a plurality of filter circuits for attenuating specific frequency components; The wearable device according to claim 4 , wherein the signal processing unit controls the frequency characteristics of the electrical signal by switching the filter circuit based on the output of the strain gauge.

6. A wearable device worn on a user's ear, a main body; an earpiece attached to the main body; a strain gauge for measuring vibrations of air within the ear canal of the user; The earpiece has an opening, a diaphragm that closes one end of the opening is provided inside the main body, A wearable device, wherein the strain gauge is provided on a surface of the diaphragm that is not exposed on the side of the opening.

7. The wearable device according to claim 6 , further comprising a pulse wave detection unit that detects the pulse wave of the user based on the internal pressure fluctuation occurring in the ear canal of the user indicated by the measurement result of the strain gauge.

8. The strain gauge has a resistor, The resistor is made of Cr, CrN, and Cr ２ The wearable device according to claim 1 or 6, which is formed from a film containing N.

9. A wearable device worn on a user's ear, a microphone for collecting sounds around the wearable device; a vibrator that contacts the side of the user's head when the wearable device is worn and vibrates in response to an electrical signal based on an output signal from the microphone; a main body portion that is abutted against or inserted into the entrance of the ear canal when the wearable device is worn; A wearable device in which a detection unit that measures vibrations of air inside the ear canal is provided on one surface of the main body that abuts the entrance of the ear canal or on one surface facing the direction in which the ear canal extends.

10. the wearable device is a hearing aid, The wearable device according to claim 9 , wherein the vibrator transmits the vibration to the user's bones, thereby transmitting the sound collected by the microphone to the user by bone conduction.

11. The wearable device according to claim 9 or 10, wherein a plurality of detectors are provided circumferentially around the edge of the one surface.

12. The wearable device according to claim 9 , further comprising a signal processing unit that controls frequency characteristics of the electrical signal based on an output of the detection unit.

13. a plurality of filter circuits for attenuating specific frequency components; The wearable device according to claim 12 , wherein the signal processing unit controls the frequency characteristics of the electrical signal by switching the filter circuit based on the output of the detection unit.

14. A wearable device worn on a user's ear, a main body; an earpiece attached to the main body; a detection unit that measures vibrations of air inside the ear canal of the user, The earpiece has an opening, a diaphragm that closes one end of the opening is provided inside the main body, A wearable device, wherein the detection unit is provided on a surface of the diaphragm that is not exposed on the opening side.

15. The wearable device according to claim 14 , further comprising a pulse wave detection unit that detects the pulse wave of the user based on the internal pressure fluctuation occurring in the ear canal of the user indicated by the measurement result of the detection unit.

16. The wearable device according to claim 9 or 14, wherein the detection unit has a detection element that detects magnetic changes that occur directly or indirectly due to vibrations of the air inside the ear canal. Lu device.

17. the detection element includes a magnetic material, The wearable device according to claim 16 , wherein the detection element detects a change in the intensity of magnetization of the magnetic body when pressure is applied to the magnetic body due to vibration of the air inside the ear canal.

18. the detection element includes a magnetic tunnel junction structure in which an insulating film is sandwiched between magnetic films, The wearable device of claim 16 , wherein the detection element detects magnetic changes generated in the structure due to vibrations of the air inside the ear canal.

19. The wearable device according to claim 9 or 14, wherein the detection unit is a semiconductor strain gauge.

20. The wearable device according to claim 9 or 14, wherein the detection unit is a capacitance type pressure sensor.

21. The wearable device according to claim 9 or 14, wherein the detection unit is an optical fiber strain gauge.

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