Patent Publication Number: US-2023139371-A1

Title: Low-frequency treatment apparatus, control method, and non-transitory recording medium in which control program is stored

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage application filed pursuant to 35 U.S.C. 365(c) and 120 as a continuation of International Patent Application No. PCT/JP2021/022945, filed Jun. 16, 2021, which application claims priority to Japanese Patent Application No. 2020-116599, filed Jul. 6, 2020, which applications are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a low-frequency treatment device, a control method, and a non-transitory recording medium in which a control program is stored. 
     BACKGROUND ART 
     Conventionally, a low-frequency treatment device is known that performs treatment of, for example, relieving shoulder stiffness of a user by attaching a pad including a conductive layer to the body of the user and supplying a low-frequency pulse current to the body. 
     Patent Document 1 describes that power is supplied to a circuit that generates electrical stimulation or heat and that the completion of preparation for applying stimulation to the body of a human or an animal by the circuit is indicated by light-emitting diodes. 
     Patent Document 2 describes a configuration in which light-emitting diodes on pads selected by a user are lighted up to assist the user to attach the proper pads to proper regions of the body before the user finishes properly attaching the pads to the body. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Document 1: JP 2015-514460 T 
         Patent Document 2: JP 2013-540543 T 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     While the effect of treatment, for example, relieving shoulder stiffness with a low-frequency pulse current has been accepted, the effect of treatment is also affected by a physical sensation of a user. Therefore, it is believed that improvement of the physical sensation of the user during treatment with the low-frequency pulse current is effective to improve the effect of treatment. 
     Further, in order to prevent muscle atrophy that may cause shoulder stiffness and the like, it is desirable to suppress worsening of symptoms by frequently performing treatment with the low-frequency pulse current. For such purpose, it is predictably effective to improve user’s motivation for treatment with the low-frequency pulse current while improving the physical sensation of the user during treatment with the low-frequency pulse current. 
     However, in the conventional technology, a physical sensation of a user during treatment depends only on electrical stimulation to the skin and muscles, which is produced by the voltage, frequency, or the like of the low-frequency pulse current, and it was difficult to improve the physical sensation of the user during treatment. Furthermore, no means for solving such a problem is disclosed in Patent Documents 1 or 2. 
     The present invention is made in view of such circumstances in one aspect, and an object of the present invention is to provide a technology that can improve a physical sensation of a user during treatment. 
     Solution to Problem 
     The present invention adopts the following configurations to solve the above-described problems. 
     In other words, a low-frequency treatment device according to one aspect of the present invention includes a pad portion configured to be able to supply a low-frequency pulse current to a contact target, and an output unit configured to outputs, during supply of the low-frequency pulse current by the pad portion, at least one of light and sound synchronized with a change in a supply state of the low-frequency pulse current. 
     In the configuration described above, the light or sound synchronized with a change in a supply state of the low-frequency pulse current is output, and thus a complex stimulation of electrical stimulation by the low-frequency pulse current and stimulation different from the electrical stimulation (at least one of visual sensation and auditory sensation) can be applied to a user. As a result, as compared to a configuration in which electrical stimulation by the low-frequency pulse current is singly applied to a user, the electrical stimulation by the low-frequency pulse current is effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     In the low-frequency treatment device according to the aspect described above, for example, a control unit is provided that is configured to perform control of supply of the low-frequency pulse current by the pad portion and control, in conjunction with the control of supply of the low-frequency pulse current, of output of at least one of the light and sound by the output unit. According to the configuration, the light or sound synchronized with a change in a supply state of the low-frequency pulse current can be output. 
     In the low-frequency treatment device according to the aspect described above, a supply state of the low-frequency pulse current includes, for example, stimulation intensity by the low-frequency pulse current to the contact target. According to the configuration, the light or sound synchronized with the stimulation intensity by the low-frequency pulse current is output, and thus electrical stimulation by the low-frequency pulse current can be effectively perceived by the user. 
     In the low-frequency treatment device according to the aspect described above, for example, the stimulation intensity includes a frequency of the low-frequency pulse current. 
     In the low-frequency treatment device according to the aspect described above, for example, the stimulation intensity includes a voltage of the low-frequency pulse current. 
     In the low-frequency treatment device according to the aspect described above, for example, the stimulation intensity includes a pulse width of the low-frequency pulse current. 
     In the low-frequency treatment device according to the aspect described above, for example, a supply state of the low-frequency pulse current includes a supply position of the low-frequency pulse current in the pad portion. According to the configuration, the light or sound synchronized with a change of the supply position of the low-frequency pulse current is output, and electrical stimulation by the low-frequency pulse current can be effectively perceived by the user. 
     In the low-frequency treatment device according to the aspect described above, the output unit may be disposed in the pad portion. According to the configuration, both electrical stimulation and stimulation different from the electrical stimulation are output from the pad portion, and thus the user can easily recognize that the both stimulations are synchronized. Thus, the electrical stimulation is more effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     In the low-frequency treatment device according to the aspect described above, for example, the pad portion includes an electrode configured to be able to supply the low-frequency pulse current, and the output unit is disposed at a position corresponding to the position of the electrode in the pad portion, and includes a light emitting unit configured to emit light in synchronization with supply of the low-frequency pulse current by the electrode. According to the configuration, both electrical stimulation and visual stimulation are output from each position to which the both stimulations correspond, and thus the user can easily recognize that the both stimulations are synchronized. Thus, the electrical stimulation is more effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. Note that the position corresponding to the position of the electrode is a position close to the electrode, and is, for example, a position closest to the electrode in the surface, which can be seen from the user, of the pad portion attached to the user. 
     In the low-frequency treatment device according to the aspect described above, the pad portion may include a plurality of electrodes configured to be able to supply the low-frequency pulse current, and the output unit may be disposed at a position corresponding to the position of each of the plurality of electrodes in the pad portion, and may include a plurality of light emitting units configured to respectively emit light in synchronization with supply of the low-frequency pulse current by the corresponding electrodes. According to the configuration, the light emitting position changes with a change of the position to which the low-frequency pulse current is supplied. Thus, the electrical stimulation is more effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     In the low-frequency treatment device according to the aspect described above, the pad portion includes, on a surface opposite to the contact target, an insulating layer covering the electrode, and the insulating layer includes a transparent member configured to diffuse light of the light emitting unit. According to the configuration, for example, even when the light emitting unit is small, an insulating film is made to emit light, and impressive visual stimulation can be applied to the user. 
     In the low-frequency treatment device according to the aspect described above, the electrode is formed of a transparent conductive film configured to diffuse light of the light emitting unit. According to the configuration, the transparent conductive film of the electrode is also made to emit light in addition to the insulating film, and impressive visual stimulation can be applied to the user. 
     In the low-frequency treatment device according to the aspect described above, for example, the output unit is configured to output light changing at least one of the color, brightness, and area in synchronization with a change in a supply state of the low-frequency pulse current. 
     In the low-frequency treatment device according to the aspect described above, the output unit may be configured to output light having color that changes depending on at least one of intensity and waveform of the low-frequency pulse current. According to this configuration, the difference in treatment content according to the intensity or waveform of the low-frequency pulse current is visually emphasized to be perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     In the low-frequency treatment device according to the aspect described above, for example, the output unit is configured to output sound with changing at least one of the sound pressure, pitch, and tone color in synchronization with a change in a supply state of the low-frequency pulse current. 
     In the low-frequency treatment device according to the aspect described above, the output unit may be configured to output sound having the tone color that changes depending on at least one of intensity and waveform of the low-frequency pulse current. According to this configuration, the difference in treatment content according to the intensity or waveform of the low-frequency pulse current is visually emphasized to be perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     A control method according to one aspect of the present invention is a control method of a low-frequency treatment device including a pad portion configured to be able to supply a low-frequency pulse current to a contact target, and an output unit, the control method including controlling the pad portion to supply the low-frequency pulse current, and controlling the output unit to output, during supply of the low-frequency pulse current by the pad portion, at least one of light and sound synchronized with a change in a supply state of the low-frequency pulse current. 
     A control program according to one aspect of the present invention is a control program of a low-frequency treatment device including a pad portion configured to be able to supply a low-frequency pulse current to a contact target, and an output unit, the control program allowing a computer to execute controlling the pad portion to supply the low-frequency pulse current, and controlling the output unit to output, during supply of the low-frequency pulse current by the pad portion, at least one of light and sound synchronized with a change in a supply state of the low-frequency pulse current. 
     Advantageous Effects of Invention 
     According to the present invention, the technology can be provided that can improve a physical sensation of a user during treatment. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a drawing illustrating a low-frequency treatment device  10  that is an application example of the present invention. 
         FIG.  2    is a perspective view illustrating the configuration of a low-frequency treatment device  20  that is an example of the low-frequency treatment device  10 . 
         FIG.  3    is an exploded perspective view illustrating a state where a pad portion  2  and a main body portion  3  of the low-frequency treatment device  20  are separated. 
         FIG.  4    is a plan view illustrating the pad portion  2  of the low-frequency treatment device  20 . 
         FIG.  5    is a bottom view illustrating the pad portion  2  of the low-frequency treatment device  20 . 
         FIG.  6    is a block diagram illustrating an example of the hardware configuration of the main body portion  3 . 
         FIG.  7    is a diagram illustrating an example of a pulse voltage applied by the main body portion  3  to a pad  21 . 
         FIG.  8    is a cross-sectional view illustrating an example of the pad  21  including a light emitter. 
         FIG.  9    is a diagram illustrating an example of the pad  21  having a multiple electrode structure. 
         FIG.  10    is a diagram illustrating an example of light emitting in a case where the pad  21  has the multiple electrode structure. 
         FIG.  11    is a diagram illustrating an example of the low-frequency treatment device  20  that outputs sound synchronized with a low-frequency pulse current. 
         FIG.  12    is a diagram illustrating the configuration of a low-frequency treatment device  200  that is another example of the low-frequency treatment device  10 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments according to an aspect of the present invention will be described below based on the drawings. 
     Application Example  FIG.  1    is a diagram illustrating the low-frequency treatment device  10  that is an application example of the present invention. 
     The low-frequency treatment device  10  is a device configured to perform treatment or the like on a user by supplying a low-frequency pulse current and applying electrical stimulation to the user. The frequency of the low-frequency pulse current is, for example, approximately 1 to 1200 Hz. The low-frequency treatment device  10  includes a pad portion  11 , a control unit  13 , and a light/sound output unit  12 . 
     The pad portion  11  can be attached to the body of the user. Also, the pad portion  11  includes an electrode  11   a , and can supply a low-frequency pulse current from the electrode  11   a  to the body of the user, which is an attachment location (a contact target). The supply of the low-frequency pulse current by the pad portion  11  is controlled by the control unit  13 . 
     The light/sound output unit  12  is an output unit that outputs, during supply of the low-frequency pulse current by the pad portion  11 , at least one of light and sound synchronized with a change in a supply state of the low-frequency pulse current. For example, the light/sound output unit  12  includes at least one of a light emitting unit and a sound emitting unit. The output of light or sound output by the light/sound output unit  12  is controlled by the control unit  13 . Synchronization is, for example, interlocking, i.e., changing at the same time. 
     The light emitting unit is a portion that appears to be luminous as viewed with the user’s eyes, and is, for example, a light source such as a light emitting diode (LED). Also, the light emitting unit may be a combination of a light source and a light guiding member that guides light of the light source. 
     The sound emitting unit is a portion that emits sound audible to the user, and is, for example, a speaker that converts an electrical signal to sound. Also, the sound emitting unit may be a combination of a speaker and a transmission member that transmits sound of the speaker. 
     The light synchronized with a change in a supply state of the low-frequency pulse current is, for example, light changing at least one of the color, brightness, and area in synchronization with a change in a supply state of the low-frequency pulse current. The area of light is the area of a portion that emits light. For example, the light/sound output unit  12  is a light emitting unit that emits light, at least one of the color, brightness, and area of which is proportional to the stimulation intensity of the low-frequency pulse current. As an example, in accordance with the control by the control unit  13 , the light/sound output unit  12  emits light when the low-frequency pulse current is supplied, and does not emit light when the low-frequency pulse current is not supplied. 
     The sound synchronized with a change in a supply state of the low-frequency pulse current is, for example, sound changing at least one of the sound pressure, pitch, and tone color in synchronization with a change in a supply state of the low-frequency pulse current. For example, the light/sound output unit  12  is a sound emitting unit that outputs sound, at least one of the sound pressure, pitch, and tone color of which is proportional to the stimulation intensity of the low-frequency pulse current. As an example, in the light/sound output unit  12 , in accordance with the control by the control unit  13 , the sound is produced when the low-frequency pulse current is supplied, and the sound is not produced when the low-frequency pulse current is not supplied. 
     The control unit  13  performs a first control for controlling supply of the low-frequency pulse current by the pad portion  11 . Further, the control unit  13  performs a second control for controlling output of at least one of light and sound by the light/sound output unit  12 . 
     In addition, the control unit  13  performs the first control and the second control in conjunction with each other. In other words, the control unit  13  performs the second control based on the content of the first control or performs the first control based on the content of the second control. Thus, the light or sound that is synchronized with a change in a supply state of the low-frequency pulse current by the pad portion  11  can be output from the light/sound output unit  12 . 
     As the first control, for example, the control unit  13  generates a pulse voltage waveform for supplying the low-frequency pulse current by the electrode  11   a  and applies the generated pulse voltage waveform to the electrode  11   a . In addition, as the second control, the control unit  13  directly outputs the generated pulse voltage waveform to the light/sound output unit  12  as a drive signal for allowing the light/sound output unit  12  to output light or sound, or adds processing such as voltage conversion to the generated pulse voltage waveform and then outputs the pulse voltage waveform to the light/sound output unit  12  as a drive signal for allowing the light/sound output unit  12  to output light or sound. 
     Note that a method for performing the first control and the second control in conjunction with each other is not limited to the foregoing method. For example, the control unit  13  may separately generate a pulse voltage waveform for supplying the low-frequency pulse current by the electrode  11   a  and a drive signal for allowing the light/sound output unit  12  to output light or sound, and output the generated pulse voltage waveform and the generated drive signal respectively to the electrode  11   a  and the light/sound output unit  12 . 
     As just described, the low-frequency treatment device  10  outputs, from the light/sound output unit  12 , light or sound synchronized with a change in a supply state of the low-frequency pulse current. Thus, a complex stimulation of electrical stimulation by the low-frequency pulse current and stimulation different from the electrical stimulation (at least one of visual sensation and auditory sensation) can be applied to the user. As a result, as compared to a configuration in which electrical stimulation by the low-frequency pulse current is singly applied to a user, the electrical stimulation by the low-frequency pulse current is effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     A supply state of the low-frequency pulse current described above includes, for example, stimulation intensity to the user by the low-frequency pulse current supplied by the pad portion  11 . In other words, the pad portion  11  can adjust the stimulation intensity to the user by the low-frequency pulse current to be supplied, and the light/sound output unit  12  outputs at least one of light and sound synchronized with a change in stimulation intensity to the user by the low-frequency pulse current supplied by the pad portion  11 . 
     Additionally, a supply state of the low-frequency pulse current described above includes, for example, a supply position of the low-frequency pulse current in the pad portion  11 . In other words, the pad portion  11  can supply the low-frequency pulse current from a plurality of positions in a region in which the pad portion  11  is brought into contact with the user, and the light/sound output unit  12  outputs at least any one of light and sound synchronized with a change of the position to which the pad portion  11  supplies the low-frequency pulse current. 
     The stimulation intensity of the low-frequency pulse current includes, for example, at least one of a frequency (i.e., a period) of the low-frequency pulse current, a voltage of the low-frequency pulse current, and a pulse width of the low-frequency pulse current. For example, the higher the frequency of the low-frequency pulse current is, the shorter an interval of stimulation is, and thus the stimulation has high intensity. Further, the higher the voltage of the low-frequency pulse current is, the larger one stimulation is, and thus the stimulation has high intensity. Furthermore, the longer the pulse width of the low-frequency pulse current is, the longer one stimulation is, and thus the stimulation has high intensity. 
     Additionally, in the example illustrated in  FIG.  1   , the light/sound output unit  12  is disposed in the pad portion  11 . For example, the light/sound output unit  12  includes the aforementioned light emitting unit disposed at a position corresponding to the position of the electrode  11   a  in the pad portion  11 . The position corresponding to the position of the electrode  11   a  is a position close to the electrode  11   a , and is, for example, a position closest to the electrode  11   a  in the surface, which can be seen from the user, of the pad portion  11  attached to the user. Moreover, the light/sound output unit  12  may include the aforementioned sound emitting unit disposed in the pad portion  11 . 
     As just described, the light/sound output unit  12  that outputs light or sound is disposed in the pad portion  11  that supplies electrical stimulation, and thus the user can easily recognize that the light or sound being output is synchronized with the electrical stimulation. As a result, the electrical stimulation can be more effectively perceived by the user, and a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Additionally, the electrode  11   a  of the pad portion  11  may include a plurality of electrodes. In this case, the light/sound output unit  12  may include a plurality of light emitting units corresponding to each of the plurality of electrodes of the pad portion  11 . The plurality of light emitting units of the light/sound output unit  12  are respectively disposed in the pad portion  11  at positions corresponding to the positions of the plurality of electrodes of the pad portion  11 . In addition, the plurality of light emitting units of the light/sound output unit  12  are respectively controlled by the control unit  13  to emit light in synchronization with the supply of the low-frequency pulse current by the corresponding electrodes. 
     Thus, light or sound is output from a location near the position where the electrical stimulation is applied in the pad portion  11 . Therefore, the position to which the light or sound is output also changes in accordance with a change of the position where the electrical stimulation is applied, and the change of the position where the electrical stimulation is applied can be more effectively perceived by the user. As a result, a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Note that in the example illustrated in  FIG.  1   , configuration is described such that the light/sound output unit  12  is disposed in the pad portion  11 , but the light/sound output unit  12  may be disposed in the control unit  13  or may be disposed in a device different from the pad portion  11  and the control unit  13 . 
     Configuration of Low-Frequency Treatment Device  20  as an Example of Low-Frequency Treatment Device  10   
       FIG.  2    is a perspective view illustrating the configuration of a low-frequency treatment device  20  that is an example of the low-frequency treatment device  10 .  FIG.  3    is an exploded perspective view illustrating a state where a pad portion  2  and a main body portion  3  of the low-frequency treatment device  20  are separated.  FIG.  4    is a plan view illustrating the pad portion  2  of the low-frequency treatment device  20 .  FIG.  5    is a bottom view illustrating the pad portion  2  of the low-frequency treatment device  20 . 
     The low-frequency treatment device  20  is a cordless type low-frequency treatment device and includes the pad portion  2  and the main body portion  3 . The pad portion  2  is an example of the pad portion  11  illustrated in  FIG.  1   . The main body portion  3  is an example of the control unit  13  illustrated in  FIG.  1   . 
     In this example, the low-frequency treatment device  20  emits light in synchronization with the low-frequency pulse current supplied to the user, and thus allows electrical stimulation by the low-frequency pulse current to be effectively perceived by the user. 
     The pad portion  2  includes a pad  21  and a holder  22 . The pad  21  and holder  22  are integrated in this example. “Integrated” refers to a state in which the pad  21  and the holder  22  are non-separably combined with each other in a normal usage state. However, the pad  21  and holder  22  may be separably disposed from each other. 
     The pad  21  is a portion to be attached to the body of the user. The pad  21  includes a conductive layer  21   a  that supplies a low-frequency pulse current to the user. The conductive layer  21   a  is an example of the electrode  11   a  illustrated in  FIG.  1   . The conductive layer  21   a  is exposed on at least a portion of each of front and back surfaces of the pad  21 . In this example, the conductive layer  21   a  is exposed on the entire surface of a back surface  211  of the pad  21 , which is facing to the body side of the user, and on a portion of the front surface of the pad  21 . 
     Attaching of the pad  21  to the body of the user is performed by affixing the back surface  211  of the pad  21  to the skin of the user via a conductive gel attached to treatment portions  21 Y in the range indicated by hatching in  FIG.  5   . 
     The pad  21  is formed by layering, for example, a carbon layer that is a conductor by printing on the surface of a base material made of a soft synthetic resin, and this carbon layer is the conductive layer  21   a . The pad  21  has flexibility. The conductive layer  21   a  is provided separately for polarity (positive pole and negative pole) during energization. Note that since the pad  21  may be energized with the polarity alternately converted, the polarity is variable while the conductive layer  21   a  dedicated to the positive electrode and the conductive layer  21   a  dedicated to the negative layer are not fixedly present. 
     For example, as illustrated in  FIG.  3   , the pad  21  includes an attachment portion  21 X to be attached on the holder  22 , and the treatment portions  21 Y each of which extends from the attachment portion  21 X to at least one side and on which the conductive layer  21   a  is exposed. 
     The conductive layer  21   a  is also exposed on the front surface that is a surface of the attachment portion  21 X of the pad  21 , which faces the main body portion  3 , and this exposed portion is the pad side electrode portion  212 . The pad side electrode portion  212  is formed to be electrically connected to an electrode (not illustrated) of the main body portion  3 . 
     In this example, the conductive layer  21   a  corresponding to one pole (for example, positive pole) is exposed at one end in a width direction of the attachment portion  21 X (in an up-down direction in  FIG.  4   ), and the conductive layer  21   a   corresponding to the other pole (for example, negative pole) is exposed at the other end. 
     The holder  22  is a portion that holds the pad  21 . In this example, the holder  22  is made of a hard resin, and holds the attachment portion  21 X of the pad  21  by double-sided adhesive tape. As a result, the pad  21  and the holder  22  are integrally formed. 
     The holder  22  includes a pad holding portion  221  that holds the attachment portion  21 X of the pad  21 , and wall portions  222  located at both ends of the pad holding portion  221 . Note that holding of the pad  21  is not limited to a method by using double-sided adhesive tape and may be, for example, a method by heat welding or a method by using a paste or an adhesive. 
     The holder  22  is made of a hard resin and thus is a nonconductor. Accordingly, in a case where the pad  21  is disposed to straddle the spine on the back of the user, the holder  22  that is a nonconductor can be arranged to match the spine and the treatment portions  21 Y of the pad  21  are not overlapped with the spine. 
     Consequently, the low-frequency pulse current is prevented from flowing through the spine and the spinal cord of the user. Accordingly, the spine and the spinal cord are prevented from being damaged by the current, and the low-frequency treatment device  20  can be safely used. In addition, it is not necessary to cover a portion of the attachment portion  21 X of the pad  21 , which may overlap the spine, by a separate insulating member, and thus the configuration of the pad portion  2  can be simplified. 
     The pad  21  is a consumable item, and the pad  21  can be attached and detached with respect to the main body portion  3  in case of replacement or the like. In this example, the holder  22  is integrally formed with the pad  21  to form the pad portion  2 , and the main body portion  3  is configured to be attached and detached with respect to the holder  22 . Replacement of the pad  21  is made, for example, by replacing the holder  22  as a whole. 
     The main body portion  3  is a portion attached to the holder  22  to apply the low-frequency pulse current to the conductive layer  21   a  of the pad  21 . A power supply unit such as a battery and an electric circuit (a substrate) configured to form a desired low-frequency pulse current may be disposed inside the main body portion  3 , and switches or a display unit may be disposed outside the main body portion  3 . 
     Although not illustrated, electrodes to be electrically connected to the pad side electrode portions  212  of the pad portion  2  are protruded from a lower surface of the main body portion  3 , which faces the holder  22 . The electrodes of the main body portion  3  are separately disposed for polarities. 
     Here, as illustrated in  FIG.  5   , in a state where the holder  22  is locked to the main body portion  3 , a width dimension W22 of the holder  22  is formed smaller than a width dimension W3 of the main body portion  3 . The holder  22  is made of a hard resin and thus is poor in flexibility. On the other hand, since the pad  21  has flexibility, the holder  22  is formed smaller in width than the main body portion  3 , and thus the flexibility of the pad  21  is less likely to be disturbed by the main body portion  3 . Accordingly, since the pad  21  is easily disposed along the curved surface of the body of the user, the pad portion  2  has good fittability to the body of the user. 
     Hardware Configuration of Main Body Portion  3   
       FIG.  6    is a block diagram illustrating an example of the hardware configuration of the main body portion  3 . As illustrated in  FIG.  6   , the main body portion  3  includes, for example, a processor  61 , a memory  62 , a user interface  63 , a power supply unit  64 , and a pad drive unit  65 . 
     The processor  61  is, for example, a processor such as a central processing unit (CPU) or a micro processing unit (MPU). The processor  61  functions as a control unit that controls the operation of components of the low-frequency treatment device  20  by reading out and executing a program stored in the memory  62 . Note that the processor  61  may be a combination of multiple processors. The control unit  13  illustrated in  FIG.  1    includes, for example, the processor  61 . 
     The memory  62  is realized by a random access memory (RAM), a read-only memory (ROM), a flash memory, or the like. The memory  62  stores programs to be executed by the processor  61  or data or the like to be used by the processor  61 . 
     The user interface  63  includes, for example, an input device that receives an operation input from the user, an output device that outputs information to the user, and the like. The input device can be implemented, for example, by a key, a remote controller, and the like. The output device can be implemented, for example, by a display, a speaker, and the like. Additionally, the input device and the output device may be implemented by a touch panel or the like. The user interface  63  is controlled by the processor  61 . 
     Moreover, the main body portion  3  may include a communication interface instead of the user interface  63  or in addition to the user interface  63 . The communication interface may be an interface for wireless communication or an interface for wired communication. The main body portion  3  is provided with the communication interface, and accordingly, for example, a command can be transmitted from another communication device such as a smart phone to the main body portion  3  to control the main body portion  3  or information of the main body portion  3  can be transmitted to another communication device. 
     The power supply unit  64  supplies power to each of components of the low-frequency treatment device  20 . For example, an alkaline battery or a rechargeable battery such as a lithium ion battery or a nickel hydrogen battery is used as a power source, and stabilizes a battery voltage and generates a drive voltage to be supplied to each component. In addition, the power supply unit  64  is not limited to a battery, and may be configured to supply power to each component of the low-frequency treatment device  20  by using power supplied from a home power source or the like. 
     The pad drive unit  65  applies a pulse voltage to the pad  21  and thus controls supply of the low-frequency pulse current to the user by the pad  21 . The pad drive unit  65  is controlled by the processor  61 . In  FIG.  7   , the pulse voltage applied by the pad drive unit  65  of the main body portion  3  to the pad  21  will be described. 
     Pulse Voltage Applied by Main Body Portion  3  to Pad  21   
       FIG.  7    is a diagram illustrating an example of a pulse voltage applied by the main body portion  3  to the pad  21 . A pulse voltage waveform  70  illustrated in  FIG.  7    is an example of a waveform of the pulse voltage applied by the pad drive unit  65  of the main body portion  3  to the pad  21 . 
     Parameters of the pulse voltage waveform  70  include an amplitude (voltage) V, a pulse width W, and a pulse period T (pulse frequency F = 1/T). The main body portion  3  can change the treatment content for the user by changing at least one of the parameters. 
     Specifically, the main body portion  3  increases the power supply voltage to a predetermined voltage and adjusts the increased voltage to a voltage corresponding to the set amplitude. For example, the main body portion  3  can adjust the amplitude V of the pulse voltage at a predetermined number of levels (10-stage levels) in accordance with an instruction from the user. When receiving a setting input at a certain level from the user, the main body portion  3  generates, based on the amplitude V corresponding to the level, a treatment waveform (pulse waveform) corresponding to a treatment mode and outputs the treatment waveform to the pad side electrode portion  212  of the pad  21 . 
     A plurality of treatment modes are prepared in advance in the low-frequency treatment device  20 . The treatment modes include, for example, “massage”, “tap”, “press”, and “sweep”. The main body portion  3  applies electrical stimulation corresponding to a variety of modes from the pad  21  to the user by changing a waveform of a pulse voltage applied to the pad  21 . 
     Also, the main body portion  3  adjusts the stimulation intensity by changing at least one of the amplitude V, the pulse width W, and the pulse period T of the pulse voltage. For example, as the amplitude V of the pulse voltage is larger, as the pulse width W is larger, or as the pulse period T (the higher the pulse frequency) is shorter, the stimulation intensity applied by the pad  21  to the user is higher. 
     Pad  21  With Light Emitter 
       FIG.  8    is a cross-sectional view illustrating an example of the pad  21  including a light emitter. 
     As illustrated in  FIG.  8   , the pad  21  is formed in a three-layer structure of, for example, a gel layer  81 , an indium tin oxide (ITO) film  82 , and a polyethylene terephthalate (PET) layer  83 . Also, the pad  21  is provided with a low-frequency terminal  84 , an LED terminal  85 , and an LED  86 . 
     The gel layer  81  is a layer of conductive gel that is brought into contact with the body of the user. The ITO film  82  is a transparent conductive film forming the aforementioned conductive layer  21   a . The PET layer  83  is a non-conductive transparent member that covers the ITO film  82 . Each of the low-frequency terminal  84 , the LED terminal  85 , and the LED  86  is disposed to be brought in electrical contact with the ITO film  82  and exposed from the PET layer  83 . 
     The low-frequency terminal  84  forms the aforementioned pad side electrode portion  212 . The main body portion  3  applies the aforementioned pulse voltage to the low-frequency terminal  84 . Also, the main body portion  3  applies a drive signal of the LED  86 , which is synchronized with the pulse voltage, to the LED terminal  85 . The LED  86  forms the light emitting unit included in the light/sound output unit  12  described above. 
     An electrode (the electrode  11   a ) that supplies, via the gel layer  81  to the user, a low-frequency pulse current corresponding to the pulse voltage applied from the main body portion  3  to the low-frequency terminal  84  is formed in the ITO film  82 . In addition, a circuit that allows the LED  86  to emit light based on the drive signal applied from the main body portion  3  to the LED terminal  85  is formed in the ITO film  82 . 
     The PET layer  83  is a transparent member as described above, and is a member that is visible from the user in a state where the pad  21  is attached to the body of the user. Therefore, the light emitted from the LED  86  diffuses throughout the PET layer  83  while being guided by the PET layer  83 . As a result, from the user, the PET layer  83  appears to be emitting light. In this case, the PET layer  83  also forms the light emitting unit together with the LED  86 . 
     As just described, the pad  21  includes, on an opposite surface to a surface of the gel layer  81  brought into contact with the body of the user, the PET layer  83  (an insulating layer) covering the ITO film  82 , and the PET layer  83  is a transparent member that diffuses the light of the LED  86  (light emitting unit). Accordingly, for example, even when the LED  86  as a light source is small, the PET layer  83  as an insulating film is made to emit light, and thus impressive visual stimulation can be applied to the user. 
     Note that in the example illustrated in  FIG.  8   , the LED  86  is exposed from the PET layer  83  to be directly visible to the user, but the LED  86  may not be configured to be exposed. Even in such a configuration, the PET layer  83  is made to emit light, and thus impressive visual stimulation can be applied to the user. 
     Additionally, since the ITO film  82  is also transparent, the light emitted from the LED  86  diffuses throughout the ITO film  82  while being guided by the ITO film  82 . In this case, the ITO film  82  also forms the light emitting unit together with the LED  86  and the PET layer  83 . By diffusing the light in two layers of the PET layer  83  and the ITO film  82 , more impressive visual stimulation can be applied to the user. 
     The pad  21  including a light emitter is not limited to the example illustrated in  FIG.  8   . For example, the pad  21  may be provided with various types of light emitters having insulating properties instead of the LED  86 . 
     Pad  21  in Multiple Electrode Structure 
       FIG.  9    is a diagram illustrating an example of the pad  21  having a multiple electrode structure. For example, as illustrated in  FIG.  9   , the electrode of the pad  21  may have a multiple electrode structure. 
     In the example illustrated in  FIG.  9   , the pad  21  includes electrode groups  91  and  92  in each of which a plurality of electrode portions are formed in a honeycomb geometry. The electrode group  91  is formed in one of the treatment portions  21 Y, and the electrode group  92  is formed in the other of the treatment portions  21 Y Each of the electrode groups  91  and  92  includes, for example, nine electrodes. 
     For example, the main body portion  3  (pad drive unit  65 ) applies a pulse voltage between two electrodes of the electrode group  91  (or the electrode group  92 ). Therefore, one electrode has a positive polarity and the other electrode has a negative polarity. 
     Since the electrode groups  91  and  92  are each formed in a honeycomb geometry, the area of the treatment portion  21 Y can be efficiently utilized. However, the electrode groups  91  and  92  are not limited to the honeycomb geometry, and may be formed, for example, in a matrix form. In addition, the number of electrodes in each of the treatment portions  21 Y is not limited to nine, and any number, two or more electrodes can be used. 
     Light Emitting When Pad  21  Is in Multiple Electrode Structure 
       FIG.  10    is a diagram illustrating an example of light emitting in a case where the pad  21  is in the multiple electrode structure. 
     For example, in a case where the pad  21  is in the multiple electrode structure as illustrated in  FIG.  9   , a plurality of light emitting units disposed at positions of the respective electrodes in the pad  21  are provided. For example, in the configuration of the pad  21  of  FIG.  8   , the multiple electrode structure illustrated in  FIG.  9    is formed by the ITO film  82 , and the LEDs  86  are disposed near the respective electrodes of the formed multiple electrode structure. In the example illustrated in  FIG.  9   , the electrode groups  91  and  92  each including nine electrodes are formed, and thus eighteen LEDs  86  are disposed. 
     In addition, the main body portion  3  performs control for allowing the LEDs  86  near the electrodes included in the electrode groups  91  and  92  to emit light in synchronization with low-frequency pulse currents supplied from the respective electrodes. For example, at the timing of supply of the low-frequency pulse current from a certain electrode to the user, the main body portion  3  allows the LED near the electrode to emit light as illustrated in  FIG.  10   . 
     Accordingly, for example, in a configuration where the low-frequency pulse current is supplied while changing positions by using the multiple electrode structure, a location near the position stimulated by the low-frequency pulse current locally emits light. Therefore, in addition to electrical stimulation, the position of which changes, visual stimulation, the position of which changes in conjunction with the position of the electrical stimulation can be applied to the user. 
     As a result, as compared to a configuration in which electrical stimulation, the position of which changes is singly applied to a user, the electrical stimulation by the low-frequency pulse current is effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Further, a light-shielding member may be disposed in the PET layer  83  or the ITO film  82  to partition the area of each of the electrodes included in the electrode groups  91  and  92  such that the light of the LED corresponding to a certain electrode does not leak to the region corresponding to the other electrode. Thus, each area corresponding to each electrode included in the electrode groups  91  and  92  can be independently made to emit light. 
     Furthermore, the main body portion  3  may perform control for allowing for light emitting of not only an LED corresponding to an electrode that supplies a low-frequency pulse current, but also, for example, LEDs corresponding to electrodes around the electrode. Additionally, in this case, the main body portion  3  may change the light emission area by changing, in accordance with the intensity of a low-frequency pulse current to be supplied, the number of adjacent LEDs that are allowed to emit light. 
     Color of Light, Which Changes With at Least One of Intensity and Waveform of Low-Frequency Pulse Current 
     The main body portion  3  may perform control for outputting light synchronized with the low-frequency pulse current and may change the color of the output light in accordance with at least one of the intensity and waveform (treatment mode) of the low-frequency pulse current. In this case, for example, an LED, the wavelength of which is variable is used as the LED  86 . 
     For example, in a treatment mode in which a strong low-frequency pulse current is supplied to the user, the main body portion  3  outputs light such as red that applies strong visual stimulation to the user. Also, in a treatment mode in which a weak low-frequency pulse current is supplied to the user, the main body portion  3  outputs light such as pink that applies weak visual stimulation to the user. Accordingly, the difference in treatment content according to the stimulation intensity or treatment mode is visually emphasized and perceived, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Modified Example of Light Emitting Unit That Outputs Light Synchronized with Low-Frequency Pulse Current 
     The configuration is described in which the LED  86  as a light emitting unit that outputs light synchronized with the low-frequency pulse current is disposed in the pad  21 , but is not limited to such a configuration. For example, a light emitting unit may be disposed in the main body portion  3  or in a device such as a smart phone that can communicate with the main body portion  3 . In addition, the light emitting unit is not limited to one, and a plurality of light emitting units may be disposed. 
     Low-Frequency Treatment Device  20  That Outputs Sound Synchronized with Low-Frequency Pulse Current 
       FIG.  11    is a diagram illustrating an example of the low-frequency treatment device  20  that outputs sound synchronized with a low-frequency pulse current. 
     Although the configuration in which the low-frequency treatment device  20  outputs light synchronized with the low-frequency pulse current is described, the low-frequency treatment device  20  may be configured to output sound synchronized with the low-frequency pulse current instead of light synchronized with the low-frequency pulse current or in addition to light synchronized with the low-frequency pulse current. 
     In the example illustrated in  FIG.  11   , the low-frequency treatment device  20  includes a speaker  111  in the main body portion  3 . The main body portion  3  outputs, from the speaker  111 , sound synchronized with the low-frequency pulse current supplied from the pad  21  to the user. 
     For example, the main body portion  3  outputs sound from the speaker  111  when the low-frequency pulse current is supplied, and does not output sound when the low-frequency pulse current is not supplied. Alternatively, the main body portion  3  may change, depending on the intensity of the supplied low-frequency pulse current, at least one of sound pressure, pitch, and tone color of the sound output from the speaker  111 . 
     The sound output from the speaker  111  in synchronization with the low-frequency pulse current may electronic sound such as “bleep-bleep” or may be sound that evokes specific types of stimulation such as “tap-tap”, “rat-a-tat”, “yank-yank”, or “crunch-crunch”. 
     As just described, the low-frequency treatment device  20  outputs sound synchronized with the low-frequency pulse current. Thus, complex stimulation of electrical stimulation by the low-frequency pulse current and visual stimulation can be applied to the user. As a result, as compared to a configuration in which electrical stimulation by the low-frequency pulse current is singly applied to a user, the electrical stimulation by the low-frequency pulse current is effectively perceived by the user, and thus a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Also, an output unit that outputs sound synchronized with the low-frequency pulse current is not limited to the speaker  111 , and may be a bone conduction headphone or earphone, or the like that outputs sound to a user, for example, by bringing an oscillating object into contact with the head or neck of the user, or may output sound by generating vibration with a vibrator or the like. 
     Tone Color Changing Depending on at Least One of Intensity and Waveform of Low-Frequency Pulse Current 
     The main body portion  3  may perform control for outputting sound synchronized with the low-frequency pulse current and also change tone color of the sound output depending on at least one of the intensity and waveform (treatment mode) of the low-frequency pulse current. 
     For example, in a treatment mode that supplies a strong low-frequency pulse current to a user, the main body portion  3  is configured to output sound such as a “rat-a-tat” that applies a strong auditory stimulation to the user. Additionally, in a treatment mode in which a weak low-frequency pulse current is supplied to the user, the main body portion  3  is configured to output sound such as “tap-tap” that applies weak auditory stimulation to the user. As a result, the difference in the treatment content according to the intensity of stimulation or the treatment mode is emphasized and perceived by hearing, and a physical sensation for treatment by the low-frequency pulse current can be improved. 
     Modified Example of Light Emitting Unit That Outputs Sound Synchronized with Low-Frequency Pulse Current 
     The configuration is described in which the speaker  111  that outputs sound synchronized with the low-frequency pulse current is disposed in the main body portion  3 , but is not limited to such a configuration. For example, the speaker  111  may be disposed in the pad  21  or a device such as a smart phone that can communicate with the main body portion  3 . 
       FIG.  12    is a diagram illustrating the configuration of a low-frequency treatment device  200  that is another example of the low-frequency treatment device  10 . 
     Although the cordless type low-frequency treatment device  20  is described as an example of the low-frequency treatment device  10 , but the low-frequency treatment device  10  may be the wired type low-frequency treatment device  200 , for example, as illustrated in  FIG.  12   . 
     The low-frequency treatment device  200  includes a main body portion  205  of the treatment device, a pair of pads  270  configured to be attached to a treatment site, and a cord  280  that electrically connects the pads  270  to the main body portion  205 . The low-frequency treatment device  200  is also a low-frequency treatment device that performs treatment of, for example, relieving shoulder stiffness of the user by supplying a low-frequency pulse in the same way as the low-frequency treatment device  20 . 
     The pads  270  have a sheet-like shape and are configured to be attached to the user’s body. The surface on one side of the pad  270  (the surface that does not come into contact with the body) is provided with a plug that corresponds to an electrode (not illustrated) formed on the surface on the other side (the surface that comes into contact with the body). The electrode is formed from a conductive gel-like material, for example. 
     To connect the main body portion  205  and the pad  270 , a plug  282  of the cord  280  is connected to the plug on the pad  270  and the cord  280  is inserted into the jack on the main body portion  205 . Note that when the polarity of the electrode formed on one of the pads  270  is positive, the polarity of the electrode formed on the other pad  270  is negative. 
     The main body portion  205  includes an operation interface  230  formed of various buttons, and a display  260 . The operation interface  230  includes a power button  232  for switching the power source on and off, a mode selection button  234  for selecting a treatment mode, a treatment start button  236 , and an adjustment button  238  for adjusting the intensity of electrical stimulation (stimulation intensity). 
     Note that the operation interface  230  is not limited to the configuration described above and may have any configuration that allows the user to perform a variety of operations described below. The operation interface  230  may include, for example, other buttons, a dial, a switch, and the like. 
     The electrical stimulation intensity, the remaining treatment time, the treatment mode, the mounting state of the pads  270 , and the like are displayed on the display  260 . Various messages are also displayed on the display  260 . 
     In the low-frequency treatment device  200 , the main body portion  205  and the pads  270  include a function corresponding to the main body portion  3  and the pad  21  in the low-frequency treatment device  20 . In other words, the main body portion  205  outputs from an output unit at least one of light and sound synchronized with the low-frequency pulse current supplied from the pads  270 . The output unit that outputs light or sound may be disposed in the pad  270 , may be disposed in the main body portion  205 , or may be disposed in a device such as a smart phone that can communicate with the main body portion  205 . 
     Additionally, in the low-frequency treatment device  200  illustrated in  FIG.  12   , the light emitting unit disposed in the plug  282  or the cord  280  may be configured as the output unit that outputs light synchronized with a change in a supply state of the low-frequency pulse current. 
     Control Program 
     A control program for the low-frequency treatment device  10 , the low-frequency treatment device  20 , and the low-frequency treatment device  200  is stored in a non-transitory storage medium out of which the program can be read by a computer. Such a “computer-readable storage medium” includes, for example, an optical medium such as a compact disc-ROM (CD-ROM), a magnetic storage medium such as a universal serial bus (USB) memory or a memory card, etc. Additionally, such a program can also be provided by downloading via a network such as the Internet. 
     While various embodiments have been described with reference to the drawings, needless to say, the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and it is understood that these are naturally belong within the technical scope of the present invention. Further, each of the components of the above-described embodiments may be combined as desired within a range that does not depart from the spirit of the present invention. 
     Note that the present application is based on Japanese Patent Application filed on Jul. 6, 2020 (JP 2020-116599), the content of which is incorporated herein by reference. 
     REFERENCE NUMERALS LIST 
     
         
           2 ,  11  Pad portion 
           3 ,  205  Main body portion 
           10 ,  20 ,  200  Low-frequency treatment device 
           11   a  Electrode 
           12  Light/sound output unit 
           13  Control unit 
           21 ,  270  Pad 
           21 X Attachment portion 
           21 Y Treatment portion 
           21   a  Conductive layer 
           3  Holder 
           61  Processor 
           22  Memory 
           63  User interface 
           64  Power source unit 
           65  Pad drive unit 
           70  Pulse voltage waveform 
           81  Gel layer 
           82  ITO film 
           83  PET layer 
           84  Low-frequency terminal 
           85  LED terminal 
           86  LED 
           91 ,  92  Electrode group 
           111  Speaker 
           211  Back surface 
           212  Pad side electrode portion 
           221  Pad holding portion 
           222  Wall portion 
           230  Operation interface 
           232  Power button 
           234  Mode selection button 
           236  Treatment start button 
           238  Adjustment button 
           260  Display 
           280  Cord 
           282  Plug 
         W3, W22 Width dimension