JP2010115025A - Contactless power transmission system and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To supply electric power to electronic equipment in a living body from outside the body without giving much impact on the body. <P>SOLUTION: A pair of intracorporeal electrodes 12a and 12b are disposed on the outer surface of a capsule 11, and electronic equipment is encapsulated inside the capsule 11, then the capsule 11 is disposed inside a living body. A pair of extracorporeal electrodes 22a and 22b which are dielectrically coupled to the intracorporeal electrodes 12a and 12b are mounted on the surface of the body. An AC voltage is applied to the extracorporeal electrodes 22a and 22b to induce an AC voltage in the intracorporeal electrodes 12a and 12b. The AC voltage induced in the intracorporeal electrodes 12a and 12b is rectified and applied to the electronic equipment as an operating voltage or is just applied to the electronic equipment as it is as an operating voltage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-contact power transmission system that supplies electric power to an electronic device or the like used in the body in a non-contact manner, and an electronic apparatus that operates by receiving the supply of electric power in a non-contact manner.

There are devices that operate by being implanted in the body, such as pacemakers and defibrillators implanted in the body. There are electronic devices that are swallowed and used like a capsule endoscope.
A problem common to these devices is securing a power source.

  Normally, these devices are driven by batteries, but the battery capacity is limited, so processing that increases power consumption, for example, frequent shooting at high resolution is difficult, and multi-functionality is difficult. Has a problem.

  In order to improve such a problem, methods for supplying electric power from outside the body to electronic devices inside the body are being studied. For example, a method has been proposed in which an induction coil (antenna) is arranged in an in-vivo device, a magnetic field is transmitted from the transmission coil outside the body toward the inside of the body, and an electromotive force due to electromagnetic induction is induced in the induction coil of the internal electronic device. Yes.

  However, this technique has a problem that the transmission coil becomes large and the influence on the living body is large, such as heat and stimulation due to eddy currents locally generated in the living body by the magnetic field. Moreover, the energy that can be transmitted cannot be increased so much at about 100 mW.

  Moreover, as a technique for transmitting power without contact without using a magnetic field, for example, Patent Document 1 discloses a technique for transmitting power between a card reader / writer and a contactless card by electrostatic coupling. It is disclosed.

  In the technique disclosed in Patent Document 1, the electrode of the card reader / writer and the electrode of the non-contact type card are opposed to each other, and electric power is not contacted from the card reader / writer to the non-contact type card using electrostatic coupling of the opposed electrodes. Transmit with.

JP-A-2005-79786

  However, in the case of an electronic device embedded in the body or a swallowed electronic device, it is difficult to make the electrodes arranged in these devices and the electrodes outside the body approach and face each other, and the technique of Patent Document 1 is applied as it is. I can't do it. In addition, the influence on the living body must be considered.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to have a small influence on a living body and to supply power from outside the body to an electronic device in the living body.
Another object of the present invention is to enable electric power to be supplied to an in-vivo electronic device more efficiently and non-contact than outside the body.

In order to achieve the above object, a non-contact power transmission system according to the first aspect of the present invention provides:
At least a pair of body electrodes disposed in the body;
Power supply means disposed in the body, connected to the at least one pair of body electrodes, and for supplying power induced in the at least one pair of body electrodes to an electronic device;
At least a pair of extracorporeal electrodes mounted on the body surface and inductively coupled with the in vivo electrodes;
AC power supply means for applying an AC voltage to the extracorporeal electrode.

For example, the external electrode has a larger area than the internal electrode.
For example, the at least one pair of body electrodes are arranged with their main surfaces facing each other, and the power supply means is arranged in a region between the at least one pair of body electrodes.

  For example, the at least one pair of body electrodes are combined to form a cylindrical shape.

  For example, you may further provide the electronic device which operate | moves with the electric power which the said electric power supply means outputs.

For example, the electronic device includes a battery and operates using power from the battery and power from the power supply unit.
The power supply unit includes, for example, a rectifier circuit that rectifies a voltage induced in the at least one pair of body electrodes and supplies the rectified voltage to the electronic device. Further, the power supply means may be configured by a wiring circuit or the like that supplies an AC voltage induced in the at least one pair of body electrodes to the electronic device while being AC.

  The AC power supply means applies, for example, an AC voltage having a frequency at which the output impedance matches the impedance of the living body between the extracorporeal electrodes.

  The AC power supply means preferably applies an AC voltage of, for example, 5 MHz to 10 MHz between the extracorporeal electrodes.

In order to achieve the above object, an electronic device according to a second aspect of the present invention provides:
Electronic devices used in the body,
At least a pair of in-vivo electrodes that are capacitively coupled to at least a pair of extracorporeal electrodes disposed outside the body, and in which an alternating voltage is induced by capacitive coupling with the extracorporeal electrode to which an alternating voltage is applied;
Power supply means connected to the at least one pair of body electrodes and supplying the electronic device with an alternating voltage induced in the at least one pair of body electrodes;
Is provided.

  According to the present invention, the internal electrode and the external electrode face each other through a living body that is a dielectric, and a voltage is induced in the internal electrode by electrostatic coupling, so that power can be transmitted from the external electrode to the internal electrode. Become.

A non-contact power transmission system according to Embodiment 1 of the present invention will be described with reference to the drawings.
The non-contact power transmission system of the present embodiment is a system that provides electric power from outside the body to a device placed in the body or swallowed, and includes an in-vivo device 1 and an extra-corporeal device 2.

  As shown in FIGS. 1A and 1B, the internal device 1 includes a capsule (container) 11, a pair of electrodes (internal electrodes) 12a and 12b formed on the outer surface of the capsule, and internal electrodes 12a and 12b. Rectifier circuit 13 (FIG. 2) connected to

  The capsule 11 is made of an acid-resistant insulating transparent resin or the like and has a cylindrical shape with both ends closed. The capsule 11 is formed in a size that can be swallowed by a human or an animal, for example, a length of 3 cm or less and a diameter of about 1.5 cm.

  The body electrodes 12a and 12b are made of a conductive film such as silver chloride foil or copper foil, and are affixed to the outer surface of the capsule 11, and are combined to form a cylindrical shape. The body electrodes 12a and 12b are formed in a size of 1 mm to 15 mm × 2 mm to 30 mm, for example.

  The rectifier circuit 13 is accommodated in the capsule 11 and is formed of, for example, a full-wave rectifier circuit including diodes D1 to D4 as illustrated in FIG.

Further, a battery 14 and an electronic device 17 are accommodated in the capsule 11. The electronic device 17 is configured by, for example, a camera device including an imaging device and a memory that stores a captured image, that is, a capsule endoscope device.
The rectifier circuit 13, the electronic device 17 and the like may be arranged in a space between the internal electrodes 12a and 12b so as not to hinder capacitive coupling between the internal electrodes 12a and 12b and external electrodes 22a and 22b described later. desirable.

  As shown in FIG. 3, the voltage output from the rectifier circuit 13 and the voltage applied from the battery 14 via the diode 15 are stabilized by the capacitor 16 and supplied to the electronic device 17 as an operating voltage. Due to the action of the diode 15, it is output from the battery 14 only when the output voltage of the rectifier circuit 13 and the voltage of the capacitor 16 are below a certain level, and consumption of the battery 14 is suppressed.

  On the other hand, as shown in FIG. 4, the extracorporeal device 2 includes a pair of extracorporeal electrodes 22a and 22b attached to a human body 41, and an AC power source 23 that applies an AC voltage between the pair of extracorporeal electrodes 22a and 22b. It is composed of

  The extracorporeal electrodes 22a and 22b are composed of a conductive plate such as a silver chloride plate or a copper plate having a relatively large size, for example, a length of about 3 to 20 cm and a width of about 10 to 35 cm. Is covered with an insulator.

The extracorporeal electrodes 22a and 22b are attached to the human body 41 so as to sandwich the region where the in-vivo device 1 is located. It is desirable that the extracorporeal electrodes 22a and 22b are directly attached to the body surface or disposed at a position relatively close to the body surface. In addition, it may be processed into a shape that matches the body shape of the human body 41, or a cushion may be disposed so as to be easily attached to the human body 41.
The positions where the extracorporeal electrodes 22a and 22b are arranged are arbitrary. For example, the extracorporeal electrode 22a is placed on the abdomen, the extracorporeal electrode 22b is placed on the waist, the extracorporeal electrode 22a is placed on the chest, the extracorporeal electrode 22b is placed on the back, the extracorporeal electrode 22a is placed on the right waist, The extracorporeal electrode 22b may be disposed on the left waist.

  The AC power supply 23 generates an AC voltage having a predetermined frequency and applies it between the extracorporeal electrodes 22a and 22b. As schematically shown in FIG. 8, the energy transmitted from the extracorporeal device 2 to the intracorporeal device 1 depends on the frequency, and becomes maximum at a frequency at which the output impedance of the AC power supply 23 matches the load impedance of the living tissue. . In the case of a human body, this frequency is about 5 MHz to 10 MHz, and the AC power supply 23 generates an AC voltage of this frequency.

  In the above configuration, when the capsule 11 is located in a region facing the extracorporeal electrodes 22a and 22b, the extracorporeal electrodes 22a and 22b and the intracorporeal electrodes 12a and 12b are capacitively coupled through a human body that is a dielectric. An equivalent circuit at this time is shown in FIG. The equivalent circuit in FIG. 5 is a circuit diagram when it is assumed that the internal electrodes 12a and 12b and the external electrodes 22a and 22b face each other.

  As is apparent from the equivalent circuit of FIG. 5, when an AC voltage is applied to the extracorporeal electrodes 22a and 22b, the internal electrodes 12a and 12b are opposed to each other as schematically shown in FIGS. 6 (a) and 6 (b). A voltage having a polarity opposite to that applied to the extracorporeal electrodes 22a and 22b is induced. For this reason, an alternating voltage is induced in the body electrodes 12a and 12b.

The rectifier circuit 13 rectifies and outputs the AC voltage generated in the body electrodes 12a and 12b.
The voltage stabilizing capacitor 16 is charged by the power output from the rectifier circuit 13 and the power supplied from the battery 14 via the diode 15, stabilizes the voltage, and supplies the voltage to the electronic device 17.

  The electronic device 17 operates using the electric power stored in the voltage stabilizing capacitor 16.

As described above, according to the present embodiment, electric power can be transmitted to the electronic device 17 in the body in a non-contact manner from outside the body.
For this reason, by using together with the battery 14, the operation time in the body of the electronic device 17 can be lengthened, and the electronic device 17 can be improved in performance.
Furthermore, since no magnetic field is used, the burden on the human body due to local eddy currents can be reduced.

  In the human body 41, the direction and position of the capsule 11 change, and the directions of the body electrodes 12a and 12b are not constant. For this reason, for example, as schematically shown in FIGS. 7A to 7C, the relative orientations and positions of the in-body electrodes 12a and 12b and the out-of-body electrodes 22a and 22b change. However, the extracorporeal electrodes 22a and 22b are formed to be sufficiently larger than the intracorporeal electrodes 12a and 12b, the intracorporeal electrodes 12a and 12b are formed in a cylindrical shape, and the electric field wraps around the human body 41 which is a dielectric. For example, the power can be stably transmitted to the capsule 11 regardless of the orientation of the capsule 11 or the position in the body.

(Second Embodiment)
In the first embodiment, if the current flowing through the internal electrodes 12a and 12b is too large from the external electrodes 22a and 22b, the human body is adversely affected by the thermal action and stimulation action. In general, the thermal action is represented by SAR = σ | E | ² / ρ, and the stimulating action (current density) is represented by J = σE. Here, σ is the electrical conductivity (S / m) of the living body, E is the electric field strength [V / m], and ρ is the density of the living body. In this regard, the International Non-Ionizing Radiation Protection Committee has set limits on exposure (GUIDELINES FOR LIMITING EXPOSURE TO TIME-VARYING ELECTRIC, MAGNETIC, AND ELECTROMAGNETIC FIELDS (ICNIRP), 1998). Specifically, regarding the thermal effect, occupational exposure in hospitals and the like is limited to 10 [W / kg], public exposure is limited to 2 [W / kg], and in terms of stimulation effects, occupational exposures such as hospitals Exposure is limited to f / 100 [mA / m ² ] and public exposure is limited to f / 500 [mA / m ² ] (f is frequency, unit is [Hz]). Therefore, it is desirable that the AC power source 23 adjusts the current (power) and frequency so as to satisfy this standard.

  Furthermore, even if the output frequency of the AC power supply 23 is set to any of 5 MHz to 10 MHz, the output impedance of the AC power supply 23 and the load impedance of the living tissue do not always match, and the power from the AC power supply 23 to the capsule 11 is not necessarily matched. May not be supplied efficiently.

  Therefore, in the second embodiment, the AC power supply 23 is made intelligent and the optimum frequency and current value are automatically set.

  As shown in FIG. 9, the AC power supply 23 according to the present embodiment includes a frequency converter 31, a high-frequency power amplifier 32, an ammeter 33, a voltmeter 34, and a controller 35.

The controller 35 is set in advance as to whether it is occupational exposure or public exposure.
In addition, the weight of the portion of the person wearing the extracorporeal electrodes 22a and 22b facing the extracorporeal electrodes 22a and 22b is set.

  When the application of the alternating voltage to the extracorporeal electrodes 22a and 22b is started, the controller 35 first controls the frequency converter 31 to reduce the frequency of the voltage applied to the extracorporeal electrodes 22a and 22b from a low frequency with relatively low power. Scan up to a high frequency, measure current and voltage, and identify the frequency f at which efficiency is highest.

  Subsequently, the controller 35 monitors the measured values of the ammeter 33 and the voltmeter 34 so as to control the frequency converter 31 so as to achieve the specified frequency f and satisfy the set exposure condition (limit). The amplification factor of the high frequency power amplifier 32 is controlled.

  By adopting such a configuration, it is possible to efficiently supply power from the extracorporeal device 2 to the intracorporeal device 1 and without affecting the living body.

In addition, although the example which supplies electric power to the electronic device 17 of the swallowing type was demonstrated in the said description, the structure of the electronic device 17 is arbitrary. For example, the present invention can also be applied to the case where power is supplied from outside the body to an electronic device whose position is fixed, such as an implantable pacemaker.
The positions where the extracorporeal electrodes 22a and 22b are mounted are arbitrary and may be changed as appropriate. For example, when the electronic device 17 is located in the stomach, the extracorporeal electrodes 22a and 22b are arranged at positions facing the upper abdomen, and during the time zone in which the electronic device 17 is located in the intestine, The electrodes 22a and 22b may be arranged at positions facing the lower abdomen.

  Moreover, although the example which drives the electronic device 17 using together the electric power supplied from the body and the electric power from the battery 14 was shown, the electronic device 17 is driven only by the electric power supplied from the outside without using the battery 14. You may comprise. Also in this case, it is desirable to arrange the voltage stabilizing capacitor 16.

As the rectifier circuit 13, a full-wave rectifier circuit using a diode bridge is illustrated, but other circuit configurations can be adopted.
The circuit of FIG. 3 can also be changed as appropriate. For example, the diode 15 may be removed or a higher performance voltage stabilizing circuit may be employed.
Further, a rechargeable secondary battery may be used as the battery 14, the diode 15 may be removed from the circuit of FIG. 3, and the battery 14 may be charged with the output of the rectifier circuit 13.

  Moreover, although the example which supplies the electric power to the electronic device 17 by rectifying the AC voltage induced in the body electrodes 12a and 12b by the rectifier circuit 13 has been shown, the electronic device 17 or circuit elements that can operate with the AC voltage, for example, For the LED for the light source mounted on the capsule endoscope, the AC voltage induced in the body electrodes 12a and 12b may be supplied as AC using power supply means such as wiring. Further, a rectified voltage may be applied to some circuit elements, and an alternating current may be applied to some other elements. For example, the capsule endoscope or the like has the largest power consumption in the light source part, and when the supply power is insufficient with only the energy of the battery, the power is sent to the light source part from outside the body by the capacitive coupling method. The alternating current may be supplied as it is, and other DC circuit units may be supplied with electric power from the battery.

As a structure of the body electrode, a structure that forms a pair of (a part of) a cylinder as a whole is disclosed, but other structures such as a parallel plate type electrode structure are also possible. Further, the cylinder does not have to be a complete circle in cross section, and the cross section may be an ellipse, a polygon (a quadrangle, a hexagon, an octagon, a pentagon, or the like). In addition, both the body electrode and the body electrode are not limited to a pair, and a plurality of pairs may be used.
The arrangement position of the body electrodes 12a and 12b is not limited to the outer surface of the capsule 1, and may be the inner surface or the like.

  Furthermore, the capsule 11 is not limited to a cylindrical shape, and may be spherical or box-shaped. When the capsule 11 is spherical, for example, the internal electrodes 12a and 12b also form a spherical surface (a part thereof) as a whole. When the capsule 11 is box-shaped, the body electrodes 12a and 12b are parallel plates. The intracorporeal device 1 is exemplified as a device that is swallowed from the mouth. However, when the capsule 11 is an indwelling type and the electronic device 17 is, for example, a pacemaker or a defibrillator, power is supplied to these electrical devices from outside the body. Similarly, the present invention can also be applied.

  It is also possible to arrange the body electrodes 12a and 12b on the outer surface of the casing of the electronic device 17 without using a capsule.

  As described above, the present invention can be widely used in systems that transmit power in a non-contact manner, and can also be used as a power source for electronic devices that operate in environments where it is difficult to directly connect to an external power source. It is.

It is a figure which shows the structure of the in-vivo apparatus which comprises the non-contact electric power transmission system which concerns on the 1st Embodiment of this invention, (a) is an external view, (b) is the II line | wire of (a). FIG. It is a circuit diagram which shows the structure of the rectifier circuit accommodated in the intracorporeal apparatus shown in FIG. It is a block diagram which shows the whole structure of an internal device. It is a figure which shows a mode that the structure of the external apparatus and the human body were mounted | worn. It is a circuit diagram of the equivalent circuit of an internal device and an external device. (A), (b) is drawing for demonstrating that an alternating voltage is induced in an internal body electrode by applying alternating current to an external body electrode. It is a figure which shows typically a mode that the relative position and direction of an internal electrode and an external electrode change. It is a characteristic view which shows the relationship between the frequency of the alternating voltage applied to an extracorporeal electrode, and transmission power (transmission efficiency). It is a block diagram of the alternating current power supply which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal device 2 External device 11 Capsule 12a, 12b Internal electrode 13 Rectifier circuit 14 Battery 15 Diode 16 Capacitor for voltage stabilization 17 Electronic device 22 External electrode
23 AC power supply 31 Frequency converter 32 High frequency power amplifier D1-D3 Diode I Ammeter V Voltmeter

Claims (10)

At least a pair of body electrodes disposed in the body;
Power supply means disposed in the body, connected to the at least one pair of body electrodes, and for supplying power induced in the at least one pair of body electrodes to an electronic device;
At least a pair of extracorporeal electrodes mounted on the body surface and inductively coupled with the in vivo electrodes;
AC power supply means for applying an AC voltage to the extracorporeal electrode;
A non-contact power transmission system comprising:   The non-contact power transmission system according to claim 1, wherein the extracorporeal electrode has a larger area than the intracorporeal electrode.   3. The at least one pair of body electrodes are disposed with their main surfaces facing each other, and the power supply means is disposed in a region between the at least one pair of body electrodes. The contactless power transmission system described in 1.   The contactless power transmission system according to claim 1, 2, or 3, wherein the at least one pair of body electrodes are combined to form a cylindrical shape.   The contactless power transmission system according to claim 1, further comprising: an electronic device that operates with power output from the power supply unit.   The non-contact power transmission system according to claim 5, wherein the electronic device includes a battery and operates using power from the battery and power from the power supply unit.   The power supply means rectifies a voltage induced in the at least one pair of body electrodes and supplies the rectified voltage to the electronic device, or an AC voltage induced in the at least one pair of body electrodes remains an AC voltage as the electronic device. The contactless power transmission system according to claim 1, further comprising a wiring circuit that supplies the wiring circuit.   8. The non-contact power according to claim 1, wherein the AC power supply means applies an AC voltage having a frequency at which an output impedance thereof matches an impedance of a living body between the external electrodes. Transmission system.   The contactless power transmission system according to any one of claims 1 to 8, wherein the AC power supply means applies an AC voltage of 5 MHz to 10 MHz between the external electrodes. Electronic devices used in the body,
At least a pair of in-vivo electrodes that are capacitively coupled to at least a pair of extracorporeal electrodes disposed outside the body, and in which an alternating voltage is induced by capacitive coupling with the extracorporeal electrode to which an alternating voltage is applied;
Power supply means connected to the at least one pair of body electrodes and supplying an alternating voltage induced in the at least body electrodes to the electronic device;
An electronic device comprising:

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