Muscle vibration detection sensor, electric stimulation device, and muscle vibration detection method

Abstract

To provide a muscle vibration detection sensor, an electric stimulation device, and a muscle vibration detection method capable of easily detecting a motion of a muscle with respect to an electric stimulation.SOLUTION: A muscle vibration detection sensor includes: a film whose physical property value changes due to deformation; and a circuit that outputs a detection signal obtained by detecting vibration of a muscle generated according to a motion of the muscle with respect to the electric stimulation, on the basis of a change in the physical property value of the film, when a device that gives the electric stimulation to the muscle gives the electric stimulation to the muscle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a muscle vibration detection sensor that detects muscle vibrations that occur in association with muscle movement, an electrical stimulation device, and a muscle vibration detection method. [Background technology]

[0002] In recent years, EMS (Electrical Muscle Simulation) devices that apply electrical stimulation to muscles for the purposes of beauty and weight loss have become increasingly popular. A known example of a conventional invention related to an EMS device is the electrical stimulation device described in Patent Document 1. The electrical stimulation device described in Patent Document 1 includes an electrode unit that contacts the user's skin and a control unit. The control unit outputs a stimulation control signal to the electrode unit. The electrode unit applies electrical stimulation to the user's muscles based on the stimulation control signal.

[0003] Meanwhile, electromyography (EMG) devices have traditionally been used to detect muscle movement. A known example of a conventional invention related to an electromyography device is the electromyography device described in Patent Document 2. The electromyography device described in Patent Document 2 is used in biological research fields such as measuring the movement of muscle groups or biomechanics, and in medical fields such as biofeedback or rehabilitation. The electromyography device described in Patent Document 2 detects myoelectric potentials generated from a user's muscles when the muscles relax and contract. The electromyography device described in Patent Document 2 includes a pair of detection electrodes that input the myoelectric potentials, and a mounting means for adhering the detection electrodes to the user's skin. The mounting means is, for example, an adhesive applied to the detection electrodes.

[0004] In order to more accurately evaluate the output signal of the electromyograph, an evaluation system connected to the electromyograph is sometimes provided. A known example of an invention relating to a conventional evaluation system is the sensor output signal evaluation system described in Patent Document 3. The evaluation system described in Patent Document 3 includes an index signal generating unit and an output signal evaluating unit. The output signal evaluating unit evaluates the output signal of the electromyograph using at least one of a maximum amplitude analyzing unit that evaluates the maximum amplitude of the output signal of the electromyograph per unit time according to the index signal generated by the index signal generating unit, a relaxation-time analyzing unit that evaluates output signals of the electromyograph that are below a predetermined threshold, and a contraction-time analyzing unit that evaluates output signals of the electromyograph that are above a predetermined threshold. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-94023 [Patent Document 2] Japanese Patent Application Publication No. 10-276995 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-282733 Summary of the Invention [Problem to be solved by the invention]

[0006] The electrical stimulation device described in Patent Document 1 cannot detect the user's muscle movement in response to the applied electrical stimulation, and the user's muscle movement in response to the applied electrical stimulation is not fed back to the electrical stimulation device. Therefore, the electrical stimulation device described in Patent Document 1 may not be able to apply electrical stimulation to the user's muscles that is appropriate for the user's muscle condition.

[0007] On the other hand, in the electromyography meter described in Patent Document 2, an adhesive needs to be applied to the detection electrode in order to detect the myoelectric potential more accurately. Furthermore, to detect the myoelectric potential more accurately, it is necessary to use a skin pretreatment agent to remove oil and keratin from the skin before adhering the detection electrode to the user's skin, thereby reducing the contact impedance between the detection electrode and the skin. Furthermore, to evaluate the output signal of the electromyography meter more accurately, it is necessary to provide an evaluation system such as the sensor output signal evaluation system described in Patent Document 3. Therefore, electromyography meter is difficult for EMS device users to use, and it has traditionally been difficult to detect the movement of the user's muscles in response to electrical stimulation provided by the EMS device.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a muscle vibration detection sensor, an electrical stimulation device, and a muscle vibration detection method that can easily detect muscle movement in response to electrical stimulation. [Means for solving the problem]

[0009] A muscle vibration detection sensor according to one embodiment of the present invention includes: A film whose physical properties change with deformation; a circuit that detects, when an apparatus for applying electrical stimulation to a muscle applies the electrical stimulation to the muscle, vibration of the muscle that occurs in association with the movement of the muscle in response to the electrical stimulation based on a change in the physical property value of the film, and outputs a detection signal; It is equipped with:

[0010] When an electrical stimulus is applied to a muscle, the muscle vibrates. This causes the skin near the muscle to vibrate. The vibration of the skin causes the film to deform, changing the film's physical properties. A detection signal is output based on the change in the film's physical properties. In this way, the muscle vibration detection sensor according to one embodiment of the present invention detects muscle vibration. As a result, the muscle vibration detection sensor according to one embodiment of the present invention can detect muscle movement.

[0011] The film is thin and highly flexible, allowing for flexible deformation. Therefore, it is easy to apply the film to the skin. Furthermore, since the muscle vibration detection sensor according to one embodiment of the present invention detects deformation rather than electrical signals, it is not necessary to apply an adhesive to the detection electrode. Furthermore, it is not necessary to reduce the contact impedance between the film and the skin before applying the film to the skin. Therefore, it is not necessary to remove oils and keratin from the skin using a skin pretreatment agent before applying the film to the skin. Furthermore, the muscle vibration detection sensor according to one embodiment of the present invention does not require an evaluation system such as the sensor output signal evaluation system described in Patent Document 3. Therefore, the muscle vibration detection sensor according to one embodiment of the present invention is easy to use for EMS device users. [Effects of the Invention]

[0012] According to the present invention, muscle movement in response to electrical stimulation can be easily detected. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a muscle vibration detection sensor 1, an electrical stimulation device 50, and a user 100. [Figure 2] FIG. 2 is an external view of electrical stimulation device 50. As shown in FIG. [Figure 3] FIG. 3 is a perspective view of the sensor unit 2. As shown in FIG. [Figure 4] FIG. 4 is an exploded perspective view of the sensor unit 2. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, the second negative electrode 55B, and the sensor unit 2 in Experiment 1. As shown in FIG. [Figure 6] FIG. 6 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 1 Hz in Experiment 1. [Figure 7] FIG. 7 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 10 Hz in Experiment 1. [Figure 8]FIG. 8 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, the second negative electrode 55B, and the sensor unit 2 in Experiment 2. As shown in FIG. [Figure 9] FIG. 9 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 1 Hz in Experiment 2. [Figure 10] FIG. 10 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 10 Hz in Experiment 2. [Figure 11] FIG. 11 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 100 Hz in Experiment 2. [Figure 12] FIG. 12 is an external view of electrical stimulation device 50a. [Figure 13] FIG. 13 is a block diagram of an electrical stimulation device 50a. [Figure 14] FIG. 14 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2 in Experiment 3. As shown in FIG. [Figure 15] FIG. 15 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 2 Hz in Experiment 3. [Figure 16] FIG. 16 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2 in Experiment 4. As shown in FIG. [Figure 17] FIG. 17 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 1.6 Hz in Experiment 4. [Figure 18] FIG. 18 is a block diagram of an electrical stimulation device 50b. [Figure 19] FIG. 19 is an example of an external view of electrical stimulation device 50b. [Figure 20] FIG. 20 is an example of an external view of electrical stimulation device 50b. [Figure 21] FIG. 21 is an example of an external view of electrical stimulation device 50b. [Figure 22]FIG. 21 is an example of an external view of electrical stimulation device 50b. [Figure 23] FIG. 23 is a block diagram of an electrical stimulation device 50c. [Figure 24] FIG. 24 is an example of an external view of electrical stimulation device 50c. [Figure 25] FIG. 25 is an example of a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2. In FIG. [Figure 26] FIG. 26 is an example of a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2. In FIG. [Figure 27] FIG. 27 is an example of an external view of electrical stimulation device 50c. [Figure 28] FIG. 28 is an example of a cross-sectional view of a face mask 57. [Figure 29] FIG. 29 is a block diagram of an electrical stimulation device 50d. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] The configuration of a muscle vibration detection sensor 1 according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram of muscle vibration detection sensor 1, an electrical stimulation device 50, and a user 100. Fig. 2 is an external view of electrical stimulation device 50.

[0015] Muscle vibration detection sensor 1 is used to detect muscle movement of user 100 in response to electrical stimulation applied by electrical stimulation device 50. As shown in Fig. 1, muscle vibration detection sensor 1 comprises a sensor unit 2 and a circuit 3. Sensor unit 2 includes a piezoelectric film 21, a reference electrode 22, and a signal electrode 23. Circuit 3 comprises a charge amplifier 31, a voltage amplification circuit 32, and a filter 33.

[0016] 1 and 2, electrical stimulation device 50 includes switch 51, control circuit 52, first voltage generating circuit 53A, second voltage generating circuit 53B, first positive electrode 54A, first negative electrode 55A, second positive electrode 54B, second negative electrode 55B, and housing 56. Electrical stimulation device 50 stimulates the muscles of user 100. First, the configuration of electrical stimulation device 50 will be described, and then the configuration of muscle vibration detection sensor 1 will be described.

[0017] In this embodiment, electrostimulation device 50 is a beauty device. As shown in FIG. 2, housing 56 has a shape that extends in a predetermined direction (first direction DIR1 in FIG. 2). When using electrostimulation device 50, user 100 holds the portion of housing 56 that extends in first direction DIR1. Switch 51, first positive electrode 54A, first negative electrode 55A, second positive electrode 54B, and second negative electrode 55B are each disposed on the surface of housing 56 and exposed from housing 56. Control circuit 52, first voltage generation circuit 53A, and second voltage generation circuit 53B are each housed within housing 56. User 100 uses electrostimulation device 50 by contacting first positive electrode 54A, first negative electrode 55A, second positive electrode 54B, and second negative electrode 55B to the skin of the face, such as the chin, cheek, or forehead, or the palm of the hand. Note that electrostimulation device 50 is not limited to a beauty device, but may be an EMS device. EMS devices are used to electrically stimulate the muscles of user 100. Note that the electrostimulation device according to the present invention is used to electrically stimulate muscles located in the user's face or upper limbs. When the electrostimulation device according to the present invention is used to electrically stimulate muscles located in the user's upper limbs, it is preferable that the electrostimulation device according to the present invention be used to electrically stimulate the user's biceps. In this case, the electrostimulation device according to the present invention is placed near the user's biceps.

[0018] Switch 51 includes an operation start switch 51A and a stop switch 51B. When operation start switch 51A is pressed while electrostimulator 50 is stopped, electrostimulator 50 starts operating. When stop switch 51B is pressed while electrostimulator 50 is stopped, electrostimulator 50 stops operating. The following describes the case where operation start switch 51A is pressed while electrostimulator 50 is stopped.

[0019] Control circuit 52 is connected to operation start switch 51A and stop switch 51B. When operation start switch 51A is pressed while electrical stimulation device 50 is stopped, control circuit 52 outputs control signal CS indicating the frequency and application time of the AC voltage to be generated by first voltage generation circuit 53A and second voltage generation circuit 53B.

[0020] The first voltage generating circuit 53A and the second voltage generating circuit 53B are each connected to the control circuit 52. The first voltage generating circuit 53A and the second voltage generating circuit 53B each generate a weak AC voltage based on a control signal CS. The frequency of the AC voltage generated by the second voltage generating circuit 53B is higher than the frequency of the AC voltage generated by the first voltage generating circuit 53A. More specifically, the AC voltage generated by the first voltage generating circuit 53A is used to electrically stimulate the muscles of the user 100. The frequency of the AC voltage generated by the first voltage generating circuit 53A is a relatively low frequency, for example, about 1 Hz to 100 Hz. The AC voltage generated by the second voltage generating circuit 53B is used for applying heat or penetrating a beauty ingredient into the skin of the user 100. The frequency of the AC voltage generated by the second voltage generating circuit 53B is a relatively high frequency, for example, about 1 kHz to 1 MHz. The frequencies of the AC voltages generated by the first voltage generating circuit 53A and the second voltage generating circuit 53B are not limited to the above-mentioned ranges. The AC voltages generated by the first voltage generating circuit 53A correspond to the "first AC voltage" according to the present invention. The AC voltages generated by the second voltage generating circuit 53B correspond to the "second AC voltage" according to the present invention.

[0021] The first positive electrode 54A and the first negative electrode 55A are each connected to the first voltage generating circuit 53A. The first positive electrode 54A and the first negative electrode 55A output the AC voltage generated by the first voltage generating circuit 53A. The first positive electrode 54A and the first negative electrode 55A correspond to the "first electrode" according to the present invention.

[0022] The second positive electrode 54B and the second negative electrode 55B are each connected to a second voltage generating circuit 53B. The second positive electrode 54B and the second negative electrode 55B output the AC voltage generated by the second voltage generating circuit 53B. The second positive electrode 54B and the second negative electrode 55B correspond to the "second electrode" according to the present invention.

[0023] When user 100 places first positive electrode 54A and first negative electrode 55A in contact with the skin, electrical stimulation device 50 applies electrical stimulation to muscles in the vicinity of the contact points.

[0024] Electrostimulation device 50 can also warm the vicinity of the contact points by user 100 bringing second positive electrode 54B and second negative electrode 55B into contact with the skin.

[0025] Next, the configuration of the muscle vibration detection sensor 1 will be described with reference to the drawings. Fig. 3 is a perspective view of the sensor unit 2. Fig. 4 is an exploded perspective view of the sensor unit 2.

[0026] In the sensor unit 2, directions are defined as follows. As shown in FIG. 3, the direction in which the long side LS of the first main surface S1 of the piezoelectric film 21 extends is defined as the X-axis direction. The direction in which the short side of the first main surface S1 of the piezoelectric film 21 extends is defined as the Y-axis direction. The Y-axis direction is perpendicular to the X-axis direction. The direction perpendicular to the X-axis and Y-axis directions is defined as the Z-axis direction.

[0027] 3, the sensor section 2 is in the form of a film. The sensor section 2 is highly flexible and can be deformed flexibly.

[0028] The sensor unit 2 has a rectangular shape with two short sides extending along the Y-axis direction and two long sides extending along the X-axis direction when viewed in the Z-axis direction. In this embodiment, the piezoelectric film 21, the reference electrode 22, and the signal electrode 23 each have a rectangular shape with two short sides extending along the Y-axis direction and two long sides LS extending along the X-axis direction when viewed in the Z-axis direction. The sensor unit 2 does not have to have a rectangular shape when viewed in the Z-axis direction. Furthermore, at least one of the piezoelectric film 21, the reference electrode 22, and the signal electrode 23 does not have to have a rectangular shape when viewed in the Z-axis direction.

[0029] As shown in Fig. 4, the piezoelectric film 21 has a first principal surface S1 and a second principal surface S2 aligned along the Z-axis direction. The piezoelectric film 21 is polarized by deformation, generating a potential difference between the first principal surface S1 and the second principal surface S2. That is, the electrical characteristics of the piezoelectric film 21 change as the piezoelectric film 21 is deformed. The potential difference generated between the first principal surface S1 and the second principal surface S2 depends on the amount of deformation of the piezoelectric film 21. The Young's modulus of the piezoelectric film 21 is approximately 1 MPa.

[0030] The piezoelectric film 21 is, for example, a film formed from a chiral polymer. The chiral polymer is, for example, polylactic acid (PLA) such as poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA). The main chain of PLA has a helical structure. PLA has piezoelectricity due to the molecules being oriented by uniaxial stretching. The piezoelectric film 21 has a piezoelectric constant of d14.

[0031] The stretching direction OD of the piezoelectric film 21 forms an angle of 45 degrees with respect to each of the X-axis direction and the Y-axis direction. Note that the 45 degrees may be within a range of approximately 45 degrees ±10 degrees. When the piezoelectric film 21 is stretched or compressed along the X-axis direction, a potential difference is generated between the first principal surface S1 and the second principal surface S2. Similarly, when the piezoelectric film 21 is stretched or compressed along the Y-axis direction, a potential difference is generated between the first principal surface S1 and the second principal surface S2. In this embodiment, the magnitude of the potential difference generated between the first principal surface S1 and the second principal surface S2 is proportional to the differential value of the deformation amount of the piezoelectric film 21.

[0032] The reference electrode 22 is connected to a ground potential. As shown in Fig. 3, the reference electrode 22 covers substantially the entire first main surface S1 of the piezoelectric film 21. The reference electrode 22 is fixed to the first main surface S1 with an adhesive (not shown). Note that the reference electrode 22 does not necessarily have to cover substantially the entire first main surface S1 of the piezoelectric film 21.

[0033] The signal electrode 23 is fixed to the second principal surface S2 of the piezoelectric film 21 with an adhesive (not shown). The signal electrode 23 covers substantially the entire surface of the second principal surface S2. More specifically, as shown in FIG. 4, the signal electrode 23 has a third principal surface S3 and a fourth principal surface S4 aligned along the Z-axis direction. The third principal surface S3 is in contact with the second principal surface S2. The fourth principal surface S4 is not in contact with the second principal surface S2. The signal electrode 23 outputs a potential difference generated between the first principal surface S1 and the second principal surface S2 as a charge generated by the piezoelectric film 21. As shown in FIG. 1, the signal electrode 23 is connected to a charge amplifier 31. Note that the signal electrode 23 does not necessarily have to cover substantially the entire surface of the second principal surface S2 of the piezoelectric film 21. A flexible substrate may be provided on the fourth principal surface S4. In this case, the signal electrode 23 may be formed within the flexible substrate.

[0034] The charge amplifier 31 converts the charge output by the signal electrode 23 into a voltage signal. The charge amplifier 31 is connected to a voltage amplifier circuit 32. The voltage amplifier circuit 32 amplifies the voltage signal converted by the charge amplifier 31 and outputs a detection signal DS. The voltage amplifier circuit 32 is connected to a filter 33.

[0035] The filter 33 filters the detection signal DS. In this embodiment, the filter 33 is a low-pass filter. The cutoff frequency of the filter 33 is higher than the frequency of the AC voltage generated by the first voltage generating circuit 53A of the electrical stimulation device 50 and lower than the frequency of the AC voltage generated by the second voltage generating circuit 53B. As a result, the filter 33 passes components of the detection signal DS whose frequency is close to the frequency of the AC voltage generated by the first voltage generating circuit 53A and blocks components whose frequency is close to the frequency of the AC voltage generated by the second voltage generating circuit 53B. In this embodiment, the filter 33 filters the detection signal DS output by the voltage amplifier circuit 32 and outputs the detection signal DSF. Note that the filter 33 is not limited to a low-pass filter and may be a band-pass filter, high-pass filter, or the like depending on the configuration of the electrical stimulation device 50. Furthermore, the filter 33 is not an essential component of the present invention. That is, the circuit 3 outputs the detection signal DS when it does not include the filter 33, and outputs the detection signal DSF when it includes the filter 33.

[0036] The sensor unit 2 contacts the user's 100's skin near the contact points between the first positive electrode 54A and the first negative electrode 55A and the user's 100's skin, thereby detecting muscle vibrations that occur in response to muscle movement in response to electrical stimulation provided by the electrical stimulation device 50. At this time, the fourth principal surface S4 of the signal electrode 23 contacts the user's 100's skin. When the electrical stimulation device 50 provides electrical stimulation to the user's 100's muscle, the muscle vibrates. This also causes the skin near the muscle to vibrate. The skin vibrations deform the piezoelectric film 21, which then polarizes, generating a potential difference between the first principal surface S1 and the second principal surface S2. The circuit 3 outputs a detection signal DS or a detection signal DSF detected based on the potential difference between the first principal surface S1 and the second principal surface S2. This allows the muscle vibration detection sensor 1 to detect muscle vibrations. As a result, the muscle vibration detection sensor 1 detects muscle movement. Note that substantially the entire fourth main surface S4 of the signal electrode 23 may be attached to the skin of the user 100, for example, with double-sided tape (not shown). Therefore, the fourth main surface S4 of the signal electrode 23 does not necessarily need to abut against the skin of the user 100, but only needs to face the skin of the user 100. In this case, the second main surface S2 of the piezoelectric film 21 faces the skin of the user 100.

[0037] It is noted that substantially the entire reference electrode 22 may face the skin of the user 100. In this case, the first main surface S1 of the piezoelectric film 21 faces the skin of the user 100. However, by facing the signal electrode 23 to the skin of the user 100 with double-sided tape or the like, the piezoelectric film 21 and the signal electrode 23 are covered by the reference electrode 22, and therefore the reference electrode 22 suppresses noise from being mixed into the detection signal DS, thereby improving the detection accuracy of the muscle vibration detection sensor 1. Therefore, it is more desirable for the signal electrode 23 to face the skin of the user 100 than for the reference electrode 22 to face the skin of the user 100.

[0038] The sensor unit 2 may be covered with an insulator, such as insulating tape, which can prevent noise from being mixed into the detection signal DS and improve the detection accuracy of the muscle vibration detection sensor 1.

[0039] The inventors of the present application conducted two types of experiments (hereinafter, referred to as Experiment 1 and Experiment 2) to confirm whether muscle vibration detection sensor 1 can detect muscle vibrations that occur in association with muscle movement of user 100 in response to electrical stimulation applied by electrical stimulation device 50. Experiment 1 will be described first with reference to the drawings, and then Experiment 2 will be described with reference to the drawings. FIG. 5 is a schematic diagram showing the arrangement of first positive electrode 54A, first negative electrode 55A, second positive electrode 54B, second negative electrode 55B, and sensor unit 2 in Experiment 1. FIG. 6 is a diagram showing an example of a detection signal DS when first voltage generating circuit 53A generates a 1 Hz AC voltage in Experiment 1. FIG. 7 is a diagram showing an example of a detection signal DS when first voltage generating circuit 53A generates a 10 Hz AC voltage in Experiment 1. The horizontal axes in FIGS. 6 and 7 represent time. The vertical axes in FIGS. 6 and 7 represent the detection signal DS.

[0040] 5, the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, the second negative electrode 55B, and the sensor unit 2 covered with insulating tape 4 were placed in contact with the palm of the right hand of the user 100. The sensor unit 2 covered with insulating tape 4 was placed in contact with the palm of the right hand of the user 100 with a gap between it and the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, and the second negative electrode 55B. In Experiment 1, AC voltages of two frequencies, 1 Hz and 10 Hz, were generated in the first voltage generating circuit 53A.

[0041] When first voltage generating circuit 53A generated a 1 Hz AC voltage, the frequency of detection signal DS was approximately 1 Hz. Furthermore, when first voltage generating circuit 53A generated a 10 Hz AC voltage, the frequency of detection signal DS was approximately 10 Hz. Therefore, the frequency of detection signal DS approximately matched the frequency of the AC voltage generated by first voltage generating circuit 53A. Therefore, experiment 1 confirmed that muscle vibration detection sensor 1 can detect muscle vibrations that occur in conjunction with muscle movement of user 100 in response to electrical stimulation provided by electrical stimulation device 50.

[0042] Next, Experiment 2 will be described with reference to the drawings. FIG. 8 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, the second negative electrode 55B, and the sensor unit 2 in Experiment 2. FIG. 9 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates a 1 Hz AC voltage in Experiment 2. FIG. 10 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates a 10 Hz AC voltage in Experiment 2. FIG. 11 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates a 100 Hz AC voltage in Experiment 2. The horizontal axes in FIGS. 9 to 11 each represent time. The vertical axes in FIGS. 9 to 11 each represent the detection signal DS.

[0043] In Experiment 2, as in Experiment 1, the sensor unit 2 was covered with insulating tape 4. In Experiment 2, the sensor unit 2 covered with insulating tape 4 was placed on the surface of the second positive electrode 54B. More specifically, a portion of the surface of the second positive electrode 54B was covered with the sensor unit 2 covered with insulating tape 4, and the other portion of the surface of the second positive electrode 54B was exposed. This allows the other portion of the surface of the second positive electrode 54B to be in contact with the palm of the user 100's right hand, even if a portion of the surface of the second positive electrode 54B is covered with the sensor unit 2 covered with insulating tape 4.

[0044] 8, the first positive electrode 54A, the first negative electrode 55A, the second positive electrode 54B, the second negative electrode 55B, and the sensor unit 2 covered with insulating tape 4 were placed against the palm of the right hand of the user 100. In experiment 2, the first voltage generating circuit 53A generated AC voltages at three frequencies: 1 Hz, 10 Hz, and 100 Hz.

[0045] When the first voltage generating circuit 53A generated a 1 Hz AC voltage, the frequency of the detection signal DS was approximately 1 Hz. Furthermore, when the first voltage generating circuit 53A generated a 10 Hz AC voltage, the frequency of the detection signal DS was approximately 10 Hz. Furthermore, when the first voltage generating circuit 53A generated a 100 Hz AC voltage, the frequency of the detection signal DS was approximately 100 Hz. Therefore, the frequency of the detection signal DS was approximately equal to the frequency of the AC voltage generated by the first voltage generating circuit 53A. Experiment 2 confirmed that muscle vibration detection sensor 1 can detect muscle vibrations generated in response to muscle movement of user 100 in response to electrical stimulation provided by electrical stimulation device 50, even when sensor unit 2 covered with insulating tape 4 is placed on the surface of second positive electrode 54B.

[0046] The piezoelectric film 21 is thin and highly flexible, allowing for flexible deformation. Therefore, it is easy to place the first principal surface S1 or the second principal surface S2 of the piezoelectric film 21 facing the skin of the user 100. Furthermore, because the muscle vibration detection sensor 1 detects deformation rather than electrical signals, it is not necessary to apply an adhesive to the reference electrode 22 and the signal electrode 23. Furthermore, it is not necessary to reduce the contact impedance between the sensor unit 2 and the user's skin before contacting the sensor unit 2 with the user's skin. Therefore, it is not necessary to remove oils and dead skin cells from the skin using a skin pretreatment agent before contacting the sensor unit 2 with the user's skin. Furthermore, the muscle vibration detection sensor 1 does not require an evaluation system. Therefore, the muscle vibration detection sensor 1 is easy to use for the user 100 of the EMS device. As a result, the muscle vibration detection sensor 1 can easily detect muscle movement in response to electrical stimulation.

[0047] Furthermore, muscle vibration detection sensor 1 can instantly detect muscle vibrations. More specifically, piezoelectric film 21 is instantly polarized by deformation, generating a potential difference between first principal surface S1 and second principal surface S2. Therefore, muscle vibration detection sensor 1 can instantly detect muscle vibrations that occur in association with muscle movement of user 100 in response to electrical stimulation applied by electrical stimulation device 50. As a result, muscle vibration detection sensor 1 can instantly detect muscle vibrations in response to electrical stimulation.

[0048] Furthermore, the muscle vibration detection sensor 1 can improve detection accuracy. More specifically, the Young's modulus of human skin is approximately 0.1 to 1.5 MPa. The Young's modulus of the piezoelectric film 21 is approximately 1 MPa, a value close to that of human skin. Because the Young's modulus of the piezoelectric film 21 is close to that of human skin, the piezoelectric film 21 can be brought into closer contact with the skin of the user 100, and the muscle vibration detection sensor 1 can accurately detect muscle vibrations that occur in conjunction with muscle movement in response to electrical stimulation. Note that if the Young's modulus of the piezoelectric film 21 is greater than 0 and equal to or less than 1 GPa, the piezoelectric film 21 can be brought into closer contact with the skin of the user 100, and the muscle vibration detection sensor 1 can accurately detect muscle vibrations that occur in conjunction with muscle movement in response to electrical stimulation.

[0049] Circuit 3 may further include a display circuit that displays the muscle movement of user 100 based on detection signal DS or detection signal DSF, thereby allowing user 100 to confirm the muscle movement in response to the electrical stimulation applied by electrical stimulation device 50.

[0050] [First Modification] The configuration of an electrical stimulation device 50a according to a first modified example of the present invention will be described below with reference to the drawings. FIG. 12 is an external view of electrical stimulation device 50a. FIG. 13 is a block diagram of electrical stimulation device 50a. Note that FIG. 12 shows a perspective view of first positive electrode 54A and first negative electrode 55A. Note that, for electrical stimulation device 50a according to the first modified example, only the differences from electrical stimulation device 50 according to the first embodiment will be described, and the rest will be omitted.

[0051] As shown in Fig. 12, electrical stimulation device 50a further includes a face mask 57. As shown in Fig. 13, electrical stimulation device 50a does not include second voltage generating circuit 53B, second positive electrode 54B, or second negative electrode 55B.

[0052] As shown in FIG. 12 , face mask 57 has a shape that conforms to a portion of the face. Face mask 57 has a structure in which the edges of multiple pieces of cloth are sewn together. When worn by user 100, face mask 57 has an inner surface IS57 that faces the face of user 100 and an outer surface OS57 that faces the front of user 100. Switch 51, first positive electrode 54A, and first negative electrode 55A are each disposed on face mask 57. In this modification, first positive electrode 54A and first negative electrode 55A are each disposed on face mask 57 so as to contact the left cheek of user 100 when electrostimulation device 50a is in use. Because face mask 57 has a shape that conforms to a portion of the face, first positive electrode 54A and first negative electrode 55A are more likely to contact the left cheek of user 100 when electrostimulation device 50a is in use. The arrangement of switch 51, first positive electrode 54A, and first negative electrode 55A is not limited to the arrangement shown in this modification.

[0053] In this modification, the shape of the housing 56 is a rectangular parallelepiped. However, the shape of the housing 56 is not limited to a rectangular parallelepiped. For example, the housing 56 may have a shape that conforms to the shape of a human ear. This allows the user 100 to hang the housing 56 on their ear when using the electrical stimulation device 50a, and the user 100 is less likely to be bothered by the wiring between the switch 51, the first positive electrode 54A, and the first negative electrode 55A and the housing 56. The housing 56 may also be placed on a face mask 57. This prevents the wiring between the switch 51, the first positive electrode 54A, and the first negative electrode 55A and the housing 56 from being exposed, and thus reduces the bother for the user 100.

[0054] The inventors of the present application also conducted two types of experiments (hereinafter referred to as Experiment 3 and Experiment 4) on electrical stimulation device 50a to confirm whether muscle vibration detection sensor 1 can detect muscle vibrations that occur in conjunction with muscle movement of user 100 in response to electrical stimulation applied by electrical stimulation device 50a. Experiment 3 will be described first with reference to the drawings, and then Experiment 4 will be described with reference to the drawings. FIG. 14 is a schematic diagram showing the arrangement of first positive electrode 54A, first negative electrode 55A, and sensor unit 2 in Experiment 3. Note that insulating tape 4 is omitted from FIG. 14. FIG. 15 is a diagram showing an example of detection signal DS when first voltage generating circuit 53A generates a 2 Hz AC voltage in Experiment 3. Note that the horizontal axis in FIG. 15 represents time. The vertical axis in FIG. 15 represents detection signal DS.

[0055] In Experiment 3, as in Experiments 1 and 2, the sensor unit 2 was covered with insulating tape 4. As shown in FIG. 14 , the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2 covered with insulating tape 4 were placed against the left cheek of the user 100. The sensor unit 2 covered with insulating tape 4 was placed against the left cheek of the user 100 with a gap between it and the first positive electrode 54A and the first negative electrode 55A. In Experiment 3, an AC voltage with a frequency of 2 Hz was generated in the first voltage generating circuit 53A.

[0056] When first voltage generating circuit 53A generated a 2 Hz AC voltage, the frequency of detection signal DS was approximately 2 Hz. Therefore, the frequency of detection signal DS approximately matched the frequency of the AC voltage generated by first voltage generating circuit 53A. Experiment 3 also confirmed that muscle vibration detection sensor 1 can detect muscle vibrations that occur in user 100 as a result of muscle movement in response to electrical stimulation applied by electrical stimulation device 50a.

[0057] Next, Experiment 4 will be described with reference to the drawings. FIG. 16 is a schematic diagram showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2 in Experiment 4. Note that the insulating tape 4 is omitted from FIG. 16. FIG. 17 is a diagram showing an example of the detection signal DS when the first voltage generating circuit 53A generates an AC voltage of 1.6 Hz in Experiment 4. Note that the horizontal axis in FIG. 17 represents time. The vertical axis in FIG. 17 represents the detection signal DS.

[0058] In Experiment 4, as in Experiments 1 to 3, the sensor unit 2 was covered with insulating tape 4. In Experiment 4, the sensor unit 2 covered with insulating tape 4 was placed on the surface of the first positive electrode 54A. More specifically, a portion of the surface of the first positive electrode 54A was covered with the sensor unit 2 covered with insulating tape 4, and the other portion of the surface of the first positive electrode 54A was exposed. This allows the other portion of the surface of the first positive electrode 54A to abut against the left cheek of the user 100, even if a portion of the surface of the first positive electrode 54A is covered with the sensor unit 2 covered with insulating tape 4.

[0059] 16, the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2 covered with insulating tape 4 were placed against the left cheek of the user 100. In experiment 4, the first voltage generating circuit 53A generated an AC voltage with a frequency of 1.6 Hz.

[0060] When first voltage generating circuit 53A generated an AC voltage of 1.6 Hz, the frequency of detection signal DS was approximately 1.6 Hz. Therefore, the frequency of detection signal DS approximately matched the frequency of the AC voltage generated by first voltage generating circuit 53A. Experiment 4 confirmed that muscle vibration detection sensor 1 can detect muscle vibrations that occur in conjunction with muscle movement of user 100 in response to electrical stimulation applied by electrical stimulation device 50a, even when sensor unit 2 covered with insulating tape 4 is placed on the surface of first positive electrode 54A.

[0061] [Second Modification] The configuration of an electrical stimulation device 50b according to a second modified example of the present invention will be described below with reference to the drawings. Fig. 18 is a block diagram of electrical stimulation device 50b. Figs. 19 to 22 are each an example of an external view of electrical stimulation device 50b. Note that Fig. 22 shows a perspective view of muscle vibration detection sensor 1. Note that, for electrical stimulation device 50b according to the second modified example, only the differences from electrical stimulation device 50 according to the first embodiment will be described, and the rest will be omitted.

[0062] As shown in FIG. 18 , electrical stimulation device 50b further includes muscle vibration detection sensor 1. That is, in this modification, electrical stimulation device 50 and muscle vibration detection sensor 1 are integrated. As shown in FIG. 19 , piezoelectric film 21 is disposed on the surface of housing 56 and exposed from housing 56. This allows sensor unit 2 to contact the skin of user 100 when electrical stimulation device 50b is in use. Piezoelectric film 21 is also disposed near first positive electrode 54A, first negative electrode 55A, second positive electrode 54B, and second negative electrode 55B. Charge amplifier 31, voltage amplification circuit 32, and filter 33 are each housed within housing 56.

[0063] According to the electrical stimulation device 50b, the piezoelectric film 21 is positioned near the first positive electrode 54A and the first negative electrode 55A, making it easier to detect muscle vibrations that occur in response to muscle movement in response to the electrical stimulation provided by the first positive electrode 54A and the first negative electrode 55A, thereby improving the detection accuracy of the muscle vibration detection sensor 1.

[0064] Furthermore, with the electrical stimulation device 50b, even if the piezoelectric film 21 is positioned near the second positive electrode 54B and the second negative electrode 55B, it is possible to detect muscle vibrations that occur in association with muscle movement in response to electrical stimulation provided by the first positive electrode 54A and the first negative electrode 55A.

[0065] Furthermore, in the electrostimulation device 50b, the cutoff frequency of the filter 33 is higher than the frequency of the AC voltage generated by the first voltage generating circuit 53A of the electrostimulation device 50 and lower than the frequency of the AC voltage generated by the second voltage generating circuit 53B. As a result, the filter 33 passes components of the detection signal DS whose frequency is close to the frequency of the AC voltage generated by the first voltage generating circuit 53A and blocks components whose frequency is close to the frequency of the AC voltage generated by the second voltage generating circuit 53B. Therefore, the filter 33 reduces the influence on the detection signal DS of muscle signals generated in response to muscle movement by the second positive electrode 54B and the second negative electrode 55B. As a result, the electrostimulation device 50b can accurately detect muscle vibrations generated in response to muscle movement in response to electrical stimulation provided by the first positive electrode 54A and the first negative electrode 55A, even when the piezoelectric film 21 is located near the second positive electrode 54B and the second negative electrode 55B.

[0066] Furthermore, in electrical stimulation device 50b, piezoelectric film 21 is disposed on the surface of housing 56. As a result, when electrical stimulation device 50b is in use, sensor unit 2 abuts against the skin of user 100 near the points where first positive electrode 54A and first negative electrode 55A abut against the skin of user 100. As a result, in electrical stimulation device 50b, muscle vibration detection sensor 1 can more easily detect muscle vibrations, and the detection accuracy of muscle vibration detection sensor 1 can be improved.

[0067] 20, the piezoelectric film 21 may be disposed on a portion of the surface (exposed surface) of the first positive electrode 54A. Alternatively, the piezoelectric film 21 may be disposed on a portion of the surface (exposed surface) of the first negative electrode 55A. The piezoelectric film 21 does not detect an electrical signal from the object to be measured, but generates a potential difference between the first principal surface S1 and the second principal surface S2 due to deformation. Therefore, even if the piezoelectric film 21 is disposed on a portion of the surface (exposed surface) of the first positive electrode 54A or on a portion of the surface (exposed surface) of the first negative electrode 55A, the detection signal DS is not affected by the AC voltage itself output by the first positive electrode 54A and the first negative electrode 55A. As a result, the muscle vibration detection sensor 1 can detect muscle vibrations that occur in conjunction with muscle movement in response to electrical stimulation applied by the first positive electrode 54A and the first negative electrode 55A.

[0068] 21, the piezoelectric film 21 may be disposed on the surface (exposed surface) of the second positive electrode 54B. Alternatively, the piezoelectric film 21 may be disposed on the surface (exposed surface) of the second negative electrode 55B. Even in these cases, the detection signal DS is not affected by the AC voltage itself output by the second positive electrode 54B and the second negative electrode 55B. As a result, the muscle vibration detection sensor 1 can detect muscle vibrations that occur in conjunction with muscle movement in response to electrical stimulation applied by the first positive electrode 54A and the first negative electrode 55A.

[0069] As shown in FIG. 22, the piezoelectric film 21 may be housed in the housing 56. In this case, the amount of deformation of the piezoelectric film 21 due to the deformation of the skin is reduced, resulting in a smaller amplitude of the detection signal DS. However, the muscle vibration detection sensor 1 can detect muscle vibration. Housed in the housing 56, the piezoelectric film 21 allows for greater freedom in housing design. The piezoelectric film 21 may be disposed on the back surface of the first positive electrode 54A (the surface housed in the housing 56 alongside the exposed surface). Alternatively, the piezoelectric film 21 may be disposed on the back surface of the first negative electrode 55A (the surface housed in the housing 56 alongside the exposed surface). Alternatively, the piezoelectric film 21 may be disposed on the back surface of the second positive electrode 54B (the surface housed in the housing 56 alongside the exposed surface). Alternatively, the piezoelectric film 21 may be disposed on the back surface of the second negative electrode 55B (the surface housed in the housing 56 alongside the exposed surface).

[0070] [Third Modification] The configuration of an electrical stimulation device 50c according to a third modified example of the present invention will be described below with reference to the drawings. FIG. 23 is a block diagram of the electrical stimulation device 50c. FIG. 24 is an example of an external view of the electrical stimulation device 50c. Note that FIG. 24 shows a perspective view of the first positive electrode 54A, the first negative electrode 55A, the muscle vibration detection sensor 1, and the piezoelectric film 21. FIGS. 25 and 26 are example schematic diagrams showing the arrangement of the first positive electrode 54A, the first negative electrode 55A, and the sensor unit 2, respectively. Note that for the sake of explanation, the face mask 57 is omitted from FIGS. 25 and 26. FIG. 27 is an example of an external view of the electrical stimulation device 50c. Note that FIG. 27 shows a perspective view of the first positive electrode 54A and the first negative electrode 55A. FIG. 28 is an example of a cross-sectional view of the face mask 57. Regarding electrostimulation device 50c according to the third modification, only the differences from electrostimulation device 50a according to the first modification will be described, and the rest will be omitted.

[0071] As shown in FIG. 23, electrical stimulation device 50c further includes muscle vibration detection sensor 1. That is, in this modification, electrical stimulation device 50a and muscle vibration detection sensor 1 are integrated. As shown in FIG. 24, piezoelectric film 21 is disposed on face mask 57. Piezoelectric film 21 is thin, highly flexible, and capable of supple deformation. This makes it possible to dispose piezoelectric film 21 on face mask 57. Piezoelectric film 21 is disposed on inner surface IS57 of face mask 57. This allows sensor unit 2 to abut against the face of user 100 when electrical stimulation device 50c is in use. Piezoelectric film 21 is also disposed near first positive electrode 54A and first negative electrode 55A. Charge amplifier 31, voltage amplification circuit 32, and filter 33 are each housed in housing 56.

[0072] 25, the piezoelectric film 21 is arranged on the face mask 57 so that the long side LS is aligned with the extension direction of the fibers of the muscles (for example, the zygomatic major muscle 101) of the user 100 when the user 100 wears the face mask 57. As a result, when the user 100 wears the face mask 57, the first main surface S1 or the second main surface S2 of the piezoelectric film 21 faces the skin of the user 100 so that the long side LS of the piezoelectric film 21 is aligned with the extension direction of the fibers of the muscles (for example, the zygomatic major muscle 101) of the user 100.

[0073] According to the electrical stimulation device 50c, the piezoelectric film 21 is arranged on the inner surface IS57 of the face mask 57, making it easier for the muscle vibration detection sensor 1 to detect muscle vibrations, thereby improving the detection accuracy of the muscle vibration detection sensor 1.

[0074] Furthermore, according to electrical stimulation device 50c, piezoelectric film 21 is arranged on face mask 57 so that, when user 100 wears face mask 57, long side LS is aligned with the extension direction of user 100's muscle fibers. This allows the extension direction of user 100's muscle fibers to coincide with the direction in which piezoelectricity of piezoelectric film 21 is strongest. Therefore, muscle relaxation and contraction of user 100 can be detected with high sensitivity. In the case of muscle vibration detection sensor 1 according to this modification, muscle relaxation and contraction of zygomaticus major muscle 101 can be detected with high sensitivity.

[0075] It should be noted that the muscle of the user 100 is not limited to the zygomatic major muscle 101. For example, as shown in Fig. 26, the muscle of the user 100 may be the masseter muscle 102. In this case, the muscle vibration detection sensor 1 can detect relaxation and contraction of the masseter muscle 102 with high sensitivity.

[0076] 27, the piezoelectric film 21 may be disposed on the outer surface OS57 of the face mask 57. In this case, the amount of deformation of the piezoelectric film 21 associated with the deformation of the skin is reduced, and the amplitude of the detection signal DS is therefore reduced. However, the muscle vibration detection sensor 1 can still detect muscle vibrations.

[0077] 28, the piezoelectric film 21 may be disposed between the inner surface IS57 and the outer surface OS57 of the face mask 57. In this case, the amount of deformation of the piezoelectric film 21 due to deformation of the skin is reduced, and therefore the amplitude of the detection signal DS is reduced. However, the muscle vibration detection sensor 1 can detect muscle vibrations. By disposing the piezoelectric film 21 between the inner surface IS57 and the outer surface OS57 of the face mask 57, the degree of freedom in the appearance design of the face mask 57 can be improved.

[0078] [Fourth Variation] The configuration of an electrical stimulation device 50d according to a fourth modification of the present invention will be described below with reference to the drawings. Fig. 29 is a block diagram of electrical stimulation device 50d. Regarding electrical stimulation device 50d according to the fourth modification, only differences from electrical stimulation device 50b according to the second modification will be described, and the rest will be omitted.

[0079] Electrostimulation device 50d according to the fourth modification differs from electrostimulation device 50b according to the second modification in that circuit 3 includes determination circuit 34. Accordingly, muscle vibration detection sensor 1a differs from muscle vibration detection sensor 1 in that circuit 3 includes determination circuit 34.

[0080] As shown in FIG. 29 , determination circuit 34 is connected to filter 33. Determination circuit 34 is, for example, a CPU (Central Processing Unit). Control signal CS and detection signal DSF are input to determination circuit 34. Determination circuit 34 determines whether electrostimulator 50d is correctly attached to user 100 based on control signal CS and detection signal DSF. Note that if circuit 3 does not include filter 33, determination circuit 34 may determine whether electrostimulator 50d is correctly attached to user 100 based on control signal CS and detection signal DS.

[0081] If electrical stimulation device 50d is incorrectly attached to user 100, the muscle movement of user 100 will be reduced, or the deformation of piezoelectric film 21 will no longer follow the muscle movement of user 100, thereby reducing the amount of deformation of piezoelectric film 21. Therefore, if electrical stimulation device 50d is not attached correctly to user 100, the amount of change in the value of detection signal DSF will be small.

[0082] A threshold value is set in advance in determination circuit 34. As described above, control signal CS indicates the frequency and application time of the AC voltage to be generated by first voltage generation circuit 53A and second voltage generation circuit 53B. Determination circuit 34 determines that electrostimulator 50d is correctly attached to user 100 if the amount of change in the value of detection signal DSF is equal to or greater than the threshold value during the period in which first voltage generation circuit 53A generates a voltage. Determination circuit 34 also determines that electrostimulator 50d is incorrectly attached to user 100 if the amount of change in the value of detection signal DSF is smaller than the threshold value during the period in which first voltage generation circuit 53A generates a voltage.

[0083] The length of the period used by the determination circuit 34 for determination is, for example, one cycle of the voltage to be generated by the first voltage generation circuit 53A. One cycle of the voltage to be generated by each of the first voltage generation circuit 53A and the second voltage generation circuit 53B is the reciprocal of the frequency indicated by the control signal CS. Note that the length of the period used by the determination circuit 34 for determination is not limited to one cycle of the voltage to be generated by the first voltage generation circuit 53A.

[0084] The amount of change in the value of the detection signal DSF is, for example, the difference between the maximum and minimum values ​​of the detection signal DSF during the period used for determination by the determination circuit 34. The frequency of the detection signal DSF is approximately the same as the frequency indicated by the control signal CS. Therefore, the value of the detection signal DSF may be the value of the frequency component included in the detection signal DSF and indicated by the control signal CS.

[0085] In electrostimulator 50d, determination circuit 34 determines whether electrostimulator 50d is correctly attached to user 100 based on information about the AC voltage generated by first voltage generating circuit 53A and detection signal DSF. This allows electrostimulator 50d to prompt user 100 to wear it correctly.

[0086] Circuit 3 may further include a display circuit that indicates whether electrostimulation device 50d is correctly attached to user 100 based on the determination result of determination circuit 34. This allows user 100 to confirm whether electrostimulation device 50d is correctly attached. Alternatively, circuit 3 may include an alarm circuit that issues an alarm if electrostimulation device 50d is incorrectly attached to user 100.

[0087] [Other embodiments] The muscle vibration detection sensor according to the present invention is not limited to the muscle vibration detection sensors 1 and 1a, and can be modified within the scope of the gist thereof. Furthermore, the structures of the muscle vibration detection sensors 1 and 1a may be combined in any manner.

[0088] The electrical stimulation device according to the present invention is not limited to electrical stimulation devices 50, 50a to 50d, and can be modified within the scope of the invention. Furthermore, the structures of electrical stimulation devices 50, 50a to 50d may be combined in any manner.

[0089] The stretching direction OD of the piezoelectric film 21 may form an angle of 0 degrees or 90 degrees with respect to the X-axis direction. In these cases, the twisting direction with respect to the X-axis direction and the Y-axis direction can be made to coincide with the direction in which the piezoelectricity of the piezoelectric film 21 is strongest. In this case, the muscle vibration detection sensor according to the present invention can detect twisting with respect to the X-axis direction and the Y-axis direction with high sensitivity. Note that 0 degrees may be within a range of approximately 0 degrees ±10 degrees. Furthermore, 90 degrees may be within a range of approximately 90 degrees ±10 degrees. In this way, the muscle vibration detection sensor according to the present invention can effectively detect muscle movement (bending, twisting, etc.) in a predetermined direction by appropriately setting the stretching direction OD of the piezoelectric film 21.

[0090] The muscle vibration detection sensor according to the present invention is not limited to the piezoelectric film 21 that generates a potential difference between the first principal surface S1 and the second principal surface S2 due to deformation, but may include any film whose physical properties change due to deformation. An example of a film whose physical properties change due to deformation is a film-like strain gauge. The electrical resistance of a strain gauge changes due to deformation. In other words, the electrical properties of a strain gauge change due to deformation. In this case, the detection signal DS output by the muscle vibration detection sensor according to the present invention changes based on the change in the electrical resistance of the strain gauge. The physical properties are not limited to electrical properties, but may also be mechanical properties, thermal properties, optical properties, chemical properties, etc.

[0091] The AC voltage generated by the first voltage generating circuit 53A may be changed based on the detection signal DS output by the muscle vibration detection sensor according to the present invention.

[0092] A buffer material may be provided between the skin of the user 100 and the sensor unit 2. In this case, the amount of deformation of the piezoelectric film 21 accompanying the deformation of the skin is reduced, and therefore the amplitude of the detection signal DS is reduced. However, the muscle vibration detection sensor according to the present invention can detect muscle vibrations.

[0093] The present invention has the following configuration.

[0094] (1) A film whose physical properties change with deformation; a circuit that detects, when an apparatus for applying electrical stimulation to a muscle applies the electrical stimulation to the muscle, vibration of the muscle that occurs in association with the movement of the muscle in response to the electrical stimulation based on a change in the physical property value of the film, and outputs a detection signal; A muscle vibration detection sensor equipped with

[0095] (2) The film is a piezoelectric film having a first main surface and a second main surface, and generating a potential difference between the first main surface and the second main surface when deformed. The muscle vibration detection sensor according to (1).

[0096] (3) The Young's modulus of the film is greater than 0 and less than or equal to 1 GPa. A muscle vibration detection sensor according to (1) or (2).

[0097] (4) A muscle vibration detection sensor according to any one of (1) to (3), a first electrode that outputs a first AC voltage to apply the electrical stimulation to the muscle; the film is disposed adjacent to the first electrode; The muscle is a muscle located in the user's face or upper limbs. Electrical stimulation device.

[0098] (5) The film is disposed on a portion of the surface of the first electrode. (4) An electrical stimulation device according to (4).

[0099] (6) further comprising a second electrode that outputs a second AC voltage; the frequency of the second AC voltage is higher than the frequency of the first AC voltage; the film is disposed adjacent to the second electrode; An electrical stimulation device according to (4) or (5).

[0100] (7) The film is disposed on a surface of the second electrode. (6) An electrical stimulation device according to (6).

[0101] (8) the circuit includes a filter that filters the detection signal; a cutoff frequency of the filter is higher than a frequency of the first AC voltage and lower than a frequency of the second AC voltage; An electrical stimulation device according to (6) or (7).

[0102] (9) The device further includes a housing that is held by the user, The housing has a shape that extends in a predetermined direction, The film is disposed on the surface of the housing. An electrical stimulation device according to any one of (4) to (8).

[0103] (10) The device further includes a housing that is held by the user, The housing has a shape that extends in a predetermined direction, The film is housed in the housing. An electrical stimulation device according to any one of (4) to (8).

[0104] (11) Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed on the inner surface. An electrical stimulation device according to any one of (4) to (8).

[0105] (12) Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed on the outer surface. An electrical stimulation device according to any one of (4) to (8).

[0106] (13) Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed between the inner surface and the outer surface. An electrical stimulation device according to any one of (4) to (8).

[0107] (14) Further comprising a face mask having a shape that conforms to a portion of the face, The film has a rectangular shape with short sides and long sides, The film is arranged on the face mask so that the long side is aligned with the direction in which the muscle fibers extend when the user wears the face mask. An electrical stimulation device according to any one of (4) to (8).

[0108] (15) The circuit includes a determination circuit that determines whether the electrical stimulation device is correctly attached to the user based on information about the first AC voltage and the detection signal. An electrical stimulation device according to any one of (4) to (14).

[0109] (16) a film whose physical properties change with deformation is placed opposite the skin in the vicinity of a contact point between the skin and an electrode of a device that applies electrical stimulation to muscles; the physical property value changes in accordance with the vibration of the muscle that occurs in association with the movement of the muscle in response to the electrical stimulation; outputting a detection signal detected based on the change in the physical property value; Muscle vibration detection method.

[0110] (17) The film is a piezoelectric film having a first main surface and a second main surface, and generating a potential difference between the first main surface and the second main surface when deformed. The muscle vibration detection method according to (16).

[0111] (18) The Young's modulus of the film is greater than 0 and less than or equal to 1 GPa. The muscle vibration detection method according to (16) or (17).

[0112] (19) The film has a rectangular shape with short sides and long sides, The film is placed facing the skin so that the long side is aligned with the direction in which the muscle fibers extend. A muscle vibration detection method according to any one of (16) to (18). [Explanation of symbols]

[0113] 1, 1a: Muscle vibration detection sensor 2: Sensor section 3: Circuit 21: Piezoelectric film 22:Reference electrode 23: Signal electrode 4:Insulating tape 31: Charge amplifier 32: Voltage amplifier circuit 33: Filter 34: Judgment circuit 50, 50a to 50d: Electrical stimulation device 51: Switch 51A: Operation start switch 51B: Stop switch 52: Control circuit 53A: First voltage generating circuit 53B: Second voltage generating circuit 54A: 1st positive electrode 54B: 2nd positive electrode 55A: First negative electrode 55B: second negative electrode 56: Cabinet 57: Face mask 100:User 101: Zygomaticus major 102: Masseter muscle CS: Control signal DIR1: 1st direction DS, DSF: Detection signal IS57:Inner side LS: Long side OD: Stretching direction OS57: External surface S1: First main surface S2: 2nd principal surface S3: Third principal surface S4: Fourth principal surface

Claims

1. A film whose physical properties change with deformation; a circuit that detects, when an apparatus for applying electrical stimulation to a muscle applies the electrical stimulation to the muscle, vibration of the muscle that occurs in association with the movement of the muscle in response to the electrical stimulation based on a change in the physical property value of the film, and outputs a detection signal; A muscle vibration detection sensor equipped with

2. the film is a piezoelectric film having a first main surface and a second main surface, and generating a potential difference between the first main surface and the second main surface when deformed; The muscle vibration detection sensor according to claim 1 .

3. The Young's modulus of the film is greater than 0 and less than or equal to 1 GPa.

3. The muscle vibration detection sensor according to claim 1 or 2.

4. The muscle vibration detection sensor according to claim 1 or 2; a first electrode that outputs a first AC voltage to apply the electrical stimulation to the muscle, the film is disposed adjacent to the first electrode; The muscle is a muscle located in the user's face or upper limbs. Electrical stimulation device.

5. The film is disposed on a portion of the surface of the first electrode. The electrical stimulation device according to claim 4.

6. a second electrode that outputs a second AC voltage; the frequency of the second AC voltage is higher than the frequency of the first AC voltage; the film is disposed adjacent to the second electrode; The electrical stimulation device according to claim 4.

7. The film is disposed on a surface of the second electrode. The electrical stimulation device according to claim 6.

8. the circuit includes a filter that filters the detection signal; a cutoff frequency of the filter is higher than a frequency of the first AC voltage and lower than a frequency of the second AC voltage; The electrical stimulation device according to claim 6.

9. The device further includes a housing that is held by the user, The housing has a shape that extends in a predetermined direction, The film is disposed on the surface of the housing. The electrical stimulation device according to claim 4.

10. The device further includes a housing that is held by the user, The housing has a shape that extends in a predetermined direction, The film is housed in the housing. The electrical stimulation device according to claim 4.

11. Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed on the inner surface. The electrical stimulation device according to claim 4.

12. Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed on the outer surface. The electrical stimulation device according to claim 4.

13. Further comprising a face mask having a shape that conforms to a portion of the face, The face mask has an inner surface facing the face of the user when worn by the user and an outer surface facing the front of the user, The film is disposed between the inner surface and the outer surface. The electrical stimulation device according to claim 4.

14. Further comprising a face mask having a shape that conforms to a portion of the face, The film has a rectangular shape with short sides and long sides, The film is arranged on the face mask so that the long side is aligned with the direction in which the muscle fibers extend when the user wears the face mask. The electrical stimulation device according to claim 4.

15. The circuit includes a determination circuit that determines whether the electrical stimulation device is correctly attached to the user based on information about the first AC voltage and the detection signal. The electrical stimulation device according to claim 4.

16. a film whose physical properties change with deformation is placed opposite the skin in the vicinity of a contact point between the skin and an electrode of a device that applies electrical stimulation to muscles; the physical property value changes in accordance with the vibration of the muscle that occurs in association with the movement of the muscle in response to the electrical stimulation; outputting a detection signal detected based on the change in the physical property value; Muscle vibration detection method.

17. the film is a piezoelectric film having a first main surface and a second main surface, and generating a potential difference between the first main surface and the second main surface when deformed; The muscle vibration detection method according to claim 16.

18. The Young's modulus of the film is greater than 0 and less than or equal to 1 GPa. The muscle vibration detection method according to claim 16 or 17.

19. The film has a rectangular shape with short sides and long sides, The film is placed facing the skin so that the long side is aligned with the direction in which the muscle fibers extend. The muscle vibration detection method according to claim 16 or 17.

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