JP4781047B2 - Radio capsule transmission / reception system and extracorporeal unit used therefor - Google Patents

Description

  The present invention relates to a radio capsule transmission / reception system including a radio capsule placed in a living body and an extracorporeal unit that receives biological information transmitted from the radio capsule.

  In order to measure and observe physical quantities such as temperature and pH value in a body cavity over a long period of time, a radio equipped with a sensor and a small transmitter, which is placed in a living body and transmits living body information wirelessly outside the body Extracorporeal units that receive capsules and their radio signals are known.

  For example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 exist as prior art literature information relating to such radio capsules and extracorporeal units.

  A typical example of the vehicle-mounted antenna of Patent Document 1 is shown in FIGS. FIG. 13 shows a schematic diagram of the extracorporeal unit 100 of Patent Document 1. In FIG. The extracorporeal unit 100 is a vest type worn by a subject, and includes an antenna array in which a plurality of antennas 101 are arranged, a receiving module 102, a memory 103 that can be detached from the extracorporeal unit 100, and a power source 104. The biological information received by the antenna 101 is processed by the receiving module 102 and stored in the memory 103. The power source 104 is a rechargeable battery that can be removed from the extracorporeal unit 100 and charged, and is connected to the receiving module 102 to supply power thereto.

  FIG. 14 shows an outline of the radio capsule 105 of Patent Document 1. A radio capsule 105 shown in FIG. 14 includes a sensor 105a that detects biological information, a transmitter 105b that transmits modulated biological information detected by the sensor 105a, a battery 105c that supplies power thereto, and a transmission antenna 105d. I have. This sensor 105a measures and images the pH value and temperature in the body cavity, and the measured and observed biological information is transmitted from the transmitter 105b.

  The signal transmitted from the radio capsule 105 in the body is received (scanned) by the antenna array provided in the external unit 100 worn by the subject, and is received by the demodulation circuit and the position specifying means provided in the reception module 102. Sent. The biological information is demodulated by the demodulation circuit, and the position information of the radio capsule is specified by the position specifying means from the position of the antenna 101 that received the strong signal, the reception state of the surrounding antennas 101, and the like. These biological information and radio capsule position information are stored in the memory 103 together with time information. Since all the dynamic biological information signals measured and observed are stored in the memory 103, the subject can act without inconvenience such as being fixed to the bed or being unable to move away from the side of the measuring device.

Patent Document 2 shows an example in which biological information from a radio capsule is received by an antenna of an extracorporeal unit, and position information of the radio capsule is used using a light receiving element arranged in an array. Patent Document 3 shows a power transmission antenna array for supplying power to the extracorporeal unit of Patent Document 1. Based on the position information of the radio capsule, the power transmission antenna closest to the position is used. It transmits power to the radio capsule.
JP 2001-46357 A JP 2001-46358 A Japanese Patent Laid-Open No. 2005-5502

The exchange of radio signals between the radio capsule placed in the living body and the extracorporeal unit is very characteristic as compared with the exchange of radio signals between a general mobile phone and a base station in the following points. Yes.
1. The communication distance between the radio capsule and the extracorporeal unit is an extremely short distance of about 10 cm or less.
2. The radio capsule is placed in the human body and passes through the human body, which is a dielectric having a large passage loss.

  Since the wireless communication is performed under the special conditions described above, the passage loss in the wireless communication between the radio capsule and the extracorporeal unit becomes extremely large unless an optimum antenna is used in consideration of the special conditions. When the passage loss becomes extremely large, it is necessary to increase the transmission power of the radio capsule antenna, thereby increasing the battery capacity built in the radio capsule or reducing the number of times biometric information is acquired, etc. The negative effects will occur.

  In said patent documents 1-3, the detailed content of the antenna of an extracorporeal unit is not described, and consideration to the special conditions in said radio | wireless communication is not made. As for radio capsule antennas, it can be seen that meander-shaped antennas are used in the drawings. However, when such a current type antenna is used in the human body, a large power loss occurs in the antenna itself. It is unlikely that the special conditions in the above wireless communication are taken into consideration.

  Therefore, an object of the radio capsule transmission / reception system of the present invention is to reduce passage loss in radio communication between the radio capsule and the extracorporeal unit.

  In order to achieve the above object, a radio capsule transmission / reception system of the present invention includes a sensor for detecting biological information, and a radio capsule having a transmitter for transmitting the biological information detected by the sensor using a magnetic current antenna, And an extracorporeal unit having a magnetic current antenna for receiving a signal transmitted from the magnetic current antenna of the radio capsule.

  The most important point of the present invention is that both the antenna built in the radio capsule and the antenna constituting the extracorporeal unit are magnetic current type antennas. As described above, by using the magnetic current type antenna for the radio capsule and the extracorporeal unit, it is possible to obtain an extremely great effect that the passage loss in the radio communication between the radio capsule and the extracorporeal unit can be greatly reduced. The magnetic current type antenna is a general term for a group of antennas attached based on the operation of the antenna. Specific examples of the antenna include a loop antenna, a microstrip antenna, and a plate-like inverted F antenna.

  The following explains why the passage loss can be reduced in the wireless communication under the above special conditions when the magnetic current type antenna is used for the radio capsule and the extracorporeal unit.

  First, when the antenna built into the radio capsule is a magnetic current type antenna, when it is a current type antenna (generic name for a dipole antenna, a monopole antenna, etc.), an electric field generated around each antenna, Consider a magnetic field. When the frequency used for communication between the radio capsule and the extracorporeal unit is the most common frequency between 300 MHz and 500 MHz, the antenna size built in the radio capsule is extremely small with respect to the wavelength. Become. This is because it is necessary to suppress the radio capsule to a size that can be swallowed by a person (diameter: 10 mm, length: about 25 mm). Therefore, when considering the electric field and magnetic field around the antenna, the target is a minute loop antenna (loop circumference length << wavelength) for a magnetic current type antenna, and a minute dipole antenna (dipole element length << wavelength) for a current type antenna. Is best.

  (Equation 1) to (Equation 4) representing the electric field and magnetic field around the minute loop antenna shown in FIG.

  (Equation 5) to (Equation 8) representing the electric field and magnetic field around the minute dipole antenna shown in FIG.

In the minute loop antenna, the electric field / magnetic field component that is radiated to a region far away from the wavelength and does not return energy to the minute loop antenna is proportional to 1 / r of (Equation 2) and (Equation 3). Only ingredients. The components of 1 / r ² and 1 / r ³ in (Equation 1) to (Equation 3) are not consumed by radiating their energy far away, but are components of reactive power existing around the minute loop antenna. It is. As this component approaches the minute loop antenna, the component increases in inverse proportion to the square and third power of the distance. For this reason, when a dielectric or magnetic material having an unsatisfactory tan δ value is present in the vicinity of the minute loop antenna, energy is consumed by these dielectric and magnetic materials, and should return to the minute loop antenna. The energy of 1 / r ² and 1 / r ³ in (Equation 1) to (Equation 3) does not return to the antenna, leading to a significant deterioration in the radiation efficiency of the micro loop antenna.

The minute dipole antenna is the same as in the case of the minute loop antenna, and the electric field / magnetic field component that is radiated to a region far away from the wavelength and does not return energy to the minute dipole antenna is (Equation 6): It is only a component proportional to 1 / r of (Formula 7). In addition, the 1 / r ² and 1 / r ³ components of (Equation 5) to (Equation 7) are not consumed when the energy is radiated far away, but the reactive power existing around the minute dipole antenna. It is a component.

Here, attention should be paid to the ratio between the electric field and the magnetic field in the vicinity of each antenna. FIG. 3 shows the ratio of the electric field to the magnetic field (= E / H) at θ = 90 degrees of the minute loop antenna and the minute dipole antenna. 3 considers that the radio capsule is placed in the human body, and in the relative permittivity of fat at 300 MHz: 5.7, (Equation 2), (Equation 3) and (Equation 6), 7). In FIG. 3, the horizontal axis represents the distance from the antenna normalized by the wavelength. From FIG. 3, it can be seen that the ratio of the electric field and the magnetic field of the minute dipole antenna and the minute loop antenna takes almost the same value in a space separated from the antenna by one wavelength or more. This is because the active power component of 1 / r in (Equation 2), (Equation 3), (Equation 6), and (Equation 7) becomes mainstream in a space that is one wavelength or more away from the antenna, and 1 / r ² and 1 This means that the reactive power component of / r ³ is extremely small compared to the active power contributing to radiation. On the other hand, the aspect changes completely in a space within one wavelength from the antenna, particularly in a space within 0.3 wavelength. For a small dipole antenna, the ratio of the electric field E increases exponentially as it approaches the antenna. In the case of a minute loop antenna, the ratio of the magnetic field H increases exponentially as it approaches the antenna. This is because the electric field E has a 1 / r ³ term that has the greatest sensitivity to the distance from the antenna in the vicinity of the antenna (see (Equation 1) and (Equation 2)), and the minute loop. This is because the antenna has the magnetic field H (see (Equation 5) and (Equation 6)).

  Here, the point to be noted is that the radio capsule is placed in the human body. As described above, the human body can be considered as a dielectric material having a large loss (relative permittivity of fat at 300 MHz: 5.7, tan δ: 0.73), but it is not treated as a magnetic material ( When a human body is considered as a magnetic body, the relative permeability is regarded as approximately 1 and tan δ is regarded as approximately 0). That is, in the human body, an extremely large attenuation is caused with respect to the electric field, but in the case of a magnetic field, it is not necessary to consider the attenuation by the human body.

Therefore, for the antenna in the radio capsule placed inside the human body, the reactive power components of 1 / r ² and 1 / r ³ are attenuated by the human body by using an antenna with a small E / H value around the antenna. It turns out that it becomes possible to reduce the ratio to do. Therefore, a magnetic current type antenna having properties like a micro loop antenna is used as the antenna built in the radio capsule of the radio capsule transmission / reception system of the present invention. As a result, the radiation efficiency of the antenna built in the radio capsule can be greatly improved, and as a result, the transmission power of the radio capsule can be greatly reduced, the battery size is reduced, and the operating time of the radio capsule is prolonged. Can be achieved.

  From FIG. 3, it can be seen that the slope of the E / H curve becomes gentle as the wavelength is away from the antenna by about 0.3 wavelength and approaches the steady value. Therefore, considering that the distance between the radio capsule placed in the human body and the extracorporeal unit is about 10 cm, if a frequency of about 1 GHz or less where the 0.3 wavelength is 10 cm is used for radio communication, propagation between antennas is possible. Loss can be effectively reduced.

  Next, the reason why the passage loss between the radio capsule and the extracorporeal unit can be reduced by using a magnetic current type antenna as the antenna constituting the extracorporeal unit will be described.

  As described above, the distance between the antenna of the radio capsule and the extracorporeal unit is very close to within about 10 cm. Now, when performing wireless communication between the radio capsule and the extracorporeal unit at a frequency of 300 MHz, the distance between the antenna of the radio capsule and the extracorporeal unit is 0.1 wavelength or less. As can be seen from FIG. 3, in the space within 0.1 wavelength, the ratio of the magnetic field H of the minute loop antenna (magnetic current type antenna) is extremely high as compared with the minute dipole antenna. That is, it can be seen that the reception power can be increased by adopting a magnetic current type antenna having high sensitivity to the magnetic field H in the region within the 0.1 wavelength for the antenna of the extracorporeal unit.

  Figure 4 shows the moment method simulation (simulator) of the passage loss between the radio capsule and the extracorporeal unit when the dipole antenna that is a current type antenna is used as the antenna of the extracorporeal unit and when the loop antenna that is a magnetic current type antenna is used. : Ie3d, Zeland). The human body model in this simulation is expressed by a dielectric having a relative dielectric constant of 5.7 and tan δ of 0.73. The thickness of the human body model was examined with three types of 150 mm, 100 mm, and 50 mm, and the antenna on the radio capsule side was arranged at an intermediate position in the thickness direction of the human body model. A loop antenna, which is a magnetic current antenna, was used as the radio capsule side antenna. Furthermore, since the value of the passing loss between the antennas changes depending on the direction of the loop antenna on the radio capsule side, the passing loss when the loop antenna is placed in each of three orthogonal X, Y, and Z axes is derived. The average value thereof is shown in FIG.

  FIG. 4 shows that when a loop antenna that is a magnetic current type antenna is used as the antenna of the extracorporeal unit, the passage loss between the antennas can be greatly reduced as compared with the case where a dipole antenna that is a current type antenna is used.

  For the above reasons, it is possible to significantly reduce the inter-antenna passing loss during wireless communication via the human body by adopting a magnetic current type antenna for both the antenna built into the radio capsule and the antenna constituting the extracorporeal unit. It becomes. As a result, since the transmission output of the radio capsule and the external unit can be reduced, it is possible to change the power source of the radio capsule and the external unit to a smaller one, and the radio capsule and the external unit can be reduced in size and weight. And longer operating time.

(Embodiment 1)
FIG. 5A and FIG. 5B are block diagrams of the extracorporeal unit of the present invention.

  FIG. 5A is a block diagram of the extracorporeal unit assuming that bidirectional signals are exchanged between the radio capsule and the extracorporeal unit. A signal transmitted from the radio capsule is received by an antenna unit 1 configured by arranging a plurality of antennas in an array. The antenna selection switch 2 determines which antenna is selected as a reception antenna. It is determined by comparing the received power values. The reception signal obtained from the antenna with the maximum reception power is sent to the reception module 3, down-converted and demodulated, and the biological information obtained by the radio capsule is restored in the extracorporeal unit. This biological information is temporarily recorded in the memory 4, and after a predetermined time has passed, it is sucked up by an external personal computer or the like, and the biological information is analyzed. When a control signal is transmitted to the radio capsule, the control signal is converted into a form that facilitates wireless communication in the transmission module, and then transmitted to the radio capsule by the optimum antenna selected by the antenna changeover switch. In this block diagram, the extracorporeal unit is configured by an antenna unit in which a plurality of antennas are arranged in an array. However, the external unit may be configured by a single antenna and the antenna changeover switch may be omitted.

  FIG. 5B is a block diagram of the extracorporeal unit when the biological information from the radio capsule is only received by the extracorporeal unit. The signal from the radio capsule is received by the antenna unit 1 constituted by a single antenna, the received signal is down-converted by the receiving module 3, and the biological information obtained by the radio capsule is restored in the extracorporeal unit by demodulation. Will be. Unlike the case of FIG. 5A, since the antenna unit is composed of a single antenna, the number of coaxial cables connecting the antenna unit 1 and the receiving module 3 is only one, thereby improving the mounting feeling and reducing the weight. It becomes possible. However, when the antenna of the extracorporeal unit cannot secure good received power due to the position inside the radio capsule, it is better to use an antenna unit in which a plurality of antennas are arrayed.

  The transmission / reception unit 7 in FIG. 5A and the reception unit 8 in FIG. 5B can be configured separately from the antenna unit 1. Only the antenna unit 1 is attached to the corset and clothes, and the transmission / reception unit 7 and the reception unit 8 are fixed to the waist with a belt or the like, so that the weight of the corset and clothes can be reduced, and the wearing feeling of the person is improved. FIGS. 6 and 7 show how a person wears the extracorporeal unit.

  FIG. 6 shows a case where the antenna unit 1 is attached to a shirt. An antenna unit 1 is arranged so as to cover a part of the body that is considering obtaining biological information by radio capsules, and the antenna unit 1 is installed either on the inside or on the outside of the human body of the shirt 9. good. However, when the shirt 9 is installed inside the human body, the antenna is inserted and held in a pocket or the like provided on the shirt 9 so that the antenna unit 1 is not directly attached to the human body. . The antenna unit 1 and the transmission / reception unit 7 are connected by a coaxial cable 10, and the transmission / reception unit 7 is fixed to the waist by a belt 11.

  When the antenna unit 1 is attached to the shirt in this way, the antenna unit 1 is not directly attached to the human body, so that it is possible to improve the burden and feeling of wearing when the external unit is worn for a long time. .

  FIG. 7 shows a case where the antenna unit 1 is attached to the corset 12. Similar to the shirt of FIG. 6, the antenna unit 1 is disposed so as to cover a part of the body that is considering obtaining biometric information by radio capsules. Either inside or outside the human body may be used. The antenna unit 1 and the transmission / reception unit 7 are connected by a coaxial cable 10, and the transmission / reception unit 7 is fixed to the waist by a belt 11.

  When the antenna unit 1 is installed on the corset 12, the gap width between the human body and the antenna unit does not change every moment because the corset tightening method can be adjusted at any time according to the human body shape. It is possible to prevent a change in antenna impedance due to a change in the distance between the human body and the antenna unit.

  8A to 8C show an example of a method for attaching the antenna unit 1 to the shirt 9 or the corset 12. FIG. 8A shows a state in which a pocket 14 is provided on the inner side of the human body of the corset 12 and an antenna 13 constituting the antenna unit 1 is inserted into the pocket 14. If a method of inserting and fixing in the pocket 14 is adopted and the antenna unit 1 and the coaxial cable 10 can be removed at any time, the corset 12 and the shirt 9 can be easily washed.

  A sectional view of the pocket 14 in a state where the antenna 13 is disposed in the pocket 14 is shown in FIG. Although details of the antenna 13 are not described, a magnetic current type antenna is covered with a resin case. In order to improve the wearing feeling when the corset 12 is worn, a cushioning material 15 is provided in the pocket 14 in contact with the antenna 13. Further, the lid of the pocket 14 is closed with Velcro (registered trademark) 16 so that the antenna 13 does not move inside the pocket 14. The coaxial cable 10 extending from the antenna 13 is routed outward with respect to the human body through a through hole 17 provided in the corset 12. This is shown in FIG. FIG. 8C is an external view of the corset 12 with respect to the human body. The coaxial cable 10 drawn out from the through hole 17 is drawn to and connected to the transmission / reception unit or the reception unit while being fixed to the surface of the corset 12 by the coaxial cable fastening jig 18. This is because if the coaxial cable 10 is routed around the human body side surface of the corset 12, the wearing feeling of the corset may be impaired. Although not shown in FIG. 8C, the planar conductor is preferably disposed further outside the coaxial cable 10 with respect to the human body. This is because the influence of noise from the outside on the coaxial cable can be reduced by the planar conductor.

  8 (a) to 8 (c), the pocket 14 is provided on the human body side of the corset 12 and the antenna 13 is disposed. However, there is no problem even if the pocket 14 is provided on the outer surface of the corset 12 with respect to the human body. . This improves the feeling of wearing the human body when the extracorporeal unit is worn. The antenna 13 may be attached to the corset 12 or the shirt 9 by using Velcro (registered trademark) or the like in addition to the method of providing the pocket 14 and inserting it.

  FIG. 9 shows another method for attaching the antenna unit to the shirt 9 or the corset 12. In this case, a pocket 14 is provided on the surface of an antenna unit mounting jig 19 made of a material whose shape such as cloth is flexibly changed, and the antenna 13 constituting the antenna unit 1 is inserted and fixed therein. And this antenna unit attachment jig | tool 19 is attached to the shirt 9 or the corset 12 via fixing jigs, such as a magic tape (trademark). If the antenna unit 1 can be fixed to the shirt 9 or the corset 12 by such a method, it is possible to easily adjust the position of the antenna unit 1 according to the human body shape, and it is easy to remove the antenna unit 1 during washing. Become.

(Embodiment 2)
FIG. 10 is a cross-sectional view showing a radio capsule transmission / reception system of the present invention. A radio capsule side loop antenna 22, which is a magnetic current type antenna, is provided in a radio capsule 21 placed inside the abdomen of the human body 20. On the abdomen side of the human body 20, an external unit side loop antenna 23 constituting the antenna unit 1 is inserted and fixed in a first pocket 26 provided on the human body side of the shirt 9. The reason why the extracorporeal unit side loop antenna 23 is installed on the ventral side is that muscles having a high tan δ and a large passing loss are less on the ventral side than the back, and the passing loss between the antennas can be reduced.

  A second planar conductor 25 is installed in the third pocket 28 provided on the back side of the human body 20, and the first planar conductor 24 is located outside the human body of the shirt 9. It is inserted into the second pocket 27 provided on the outside, and installed so as to cover the extracorporeal unit side loop antenna 23. By arranging the first planar conductor 24 and the second planar conductor 25 as shown in FIG. 10, the passage loss between the radio capsule side loop antenna 22 and the extracorporeal unit side loop antenna 23 is reduced. Things will be possible. The mechanism is shown in FIGS. 11 (a), 11 (b), and 11 (c).

FIG. 11A is a schematic diagram showing the flow of electric and magnetic fields in the vicinity of the radio capsule-side loop antenna 22 built in the radio capsule 21 placed inside the human body 20, and the radiation pattern of the electric and magnetic fields. It does not represent. In FIG. 11A, an electric field / magnetic field used in wireless transmission of a signal from the radio capsule side loop antenna 22 to the extracorporeal unit side loop antenna 23 is directed from the radio capsule side loop antenna 22 to the extracorporeal unit side loop antenna 23. The electric field / magnetic field of the 1 / r term and the electric field / magnetic field of the 1 / r ² and 1 / r ³ terms. The electric field / magnetic field of the 1 / r term radiated in a direction other than the direction from the radio capsule side loop antenna 22 toward the extracorporeal unit side loop antenna 23 is not used for radio communication and becomes a part of passage loss. Therefore, as shown in FIG. 11 (b), when the first planar conductor 24 is installed, the 1 / r term radiated from the radio capsule side loop antenna 22 that has not been used for wireless communication until now is obtained. An induced current I1 flows through the first planar conductor 24 due to the electric field / magnetic field, and a part of the electric field / magnetic field (dotted arrow in FIG. 11B) re-radiated by the induced current is transferred to the extracorporeal unit side loop antenna. By receiving the signal 23, it is possible to reduce the passage loss. FIG. 11C further shows an embodiment in which the second planar conductor 25 is also arranged outside the human body of the extracorporeal unit side loop antenna 23. In the present embodiment as well, as in the case of FIG. 11B, the second electric field / magnetic field radiated from the radiocapsule loop antenna 22 that has not been used for wireless communication until now is used. The induced current I2 also flows through the planar conductor 25, and the extracorporeal unit-side loop antenna 23 receives a part of the electric field / magnetic field re-radiated by the induced current (dotted arrow in FIG. 11C). As a result, it is possible to further reduce the passage loss. Further, the second planar conductor 25 makes it difficult for the extracorporeal unit-side loop antenna 23 to receive noise from the outside, so that good communication quality can be realized.

  In FIG. 10, planar conductors are installed on both the stomach side and the back side, but it goes without saying that they may be installed only on one side. In FIG. 10, the planar conductor is fixed by inserting it into the pocket, but may be fixed by using a detaching mechanism such as Velcro (registered trademark) or a hook. Further, instead of using a planar conductor, the fibers of the shirt 9 itself may be made conductive. The second pocket 27 and the third pocket 28 can be eliminated, and the first planar conductor 24 and the second planar conductor 25 can be made flexible so that the external unit can be worn. Can be improved. Moreover, the effort which attaches a planar conductor to a shirt can be reduced. However, it is necessary to consider that conductive fibers are not used on the surface of the extracorporeal unit side loop antenna 23 that contacts the human body. This is because the passage loss between the radio capsule side loop antenna 22 and the extracorporeal unit side loop antenna 23 deteriorates.

  In FIG. 10, the antenna on the extracorporeal unit side is constituted by a loop antenna, but a microstrip antenna or a plate-like inverted F antenna may be used. However, since the loop antenna performs a balance operation only with the antenna portion, the current contributing to radiation is not distributed in the ground portion of the coaxial cable extending from the antenna, so that the influence of external noise can be reduced. There is.

  FIG. 12 shows an embodiment in which a plate-like inverted F antenna, which is a kind of magnetic current antenna, is used as the antenna on the external unit side. The planar conductor 30 installed on the back side is fixed to the corset 12 with Velcro (registered trademark). Instead of installing the planar conductor 30, conductive fibers may be attached to the entire fabric of the corset 12. However, it is necessary to consider that conductive fibers are not used on the surface of the plate-like inverted F antenna 29 that contacts the human body. This is because the passage loss between the radio capsule side loop antenna 22 and the plate-like inverted F antenna 29 deteriorates.

  The radio capsule transceiver unit according to the present invention can greatly reduce the passing loss between antennas. As a result, the size of the battery incorporated in the radio capsule can be reduced, and the radio capsule itself can be miniaturized and the use time of the radio capsule can be extended. In addition, by placing the antenna constituting the extracorporeal unit on clothes such as shirts and corsets, it is possible to avoid sticking the antenna directly to the human body, improving the interval between wearing the extracorporeal unit, Wearing an extracorporeal unit will not cause any pain. For this reason, the present invention is most suitable for use in a medical device such as a capsule endoscope that can easily obtain biological information inside the human body by drinking a small radio capsule.

Micro loop antenna model Small dipole antenna model Graph showing distance change from E / H antenna The figure which shows the passage loss between the antennas when the extracorporeal antenna is changed (A), (b) Block diagram of extracorporeal unit Figure with an external unit attached to a shirt Figure with an external unit attached to the corset (A) Top perspective view showing antenna installation method, (b) Cross-sectional view showing antenna installation method, (c) Rear perspective view showing antenna installation method Top view showing antenna installation method Sectional drawing which shows the example of the radio capsule transmission / reception system of this invention (A), (b), (c) The figure which shows the outline of the flow of the electric field and magnetic field around the radio capsule side antenna Sectional drawing which shows the example of the radio capsule transmission / reception system of this invention Figure of conventional extracorporeal unit Figure of conventional radio capsule

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna unit 2 Antenna changeover switch 3 Reception module 4 Memory 5 Transmission module 6 Battery 7 Transmission / reception unit 8 Reception unit 9 Shirt 12 Corset 21 Radio capsule 22 Radio capsule side loop antenna 23 Extracorporeal unit side loop antenna 24 First planar conductor 25 Second Planar Conductor 29 Plate-like Inverted F Antenna 100 External Unit 101 Antenna 102 Reception Module 103 Memory 104 Power Supply

Claims (12)

A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
Each of the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit is within the plane perpendicular to the direction of the magnetic field formed at the center of the magnetic current type antenna. The ratio of the magnetic field to the electric field formed by the magnetic current antenna has a characteristic of increasing as it approaches the magnetic current antenna,
A radiocapsule transmission / reception system in which the extracorporeal unit has a planar conductor disposed on the opposite side of the living body from the magnetic current type antenna constituting the extracorporeal unit. A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
Each of the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit is within the plane perpendicular to the direction of the magnetic field formed at the center of the magnetic current type antenna. The ratio of the magnetic field to the electric field formed by the magnetic current antenna has a characteristic of increasing as it approaches the magnetic current antenna,
A radiocapsule transmission / reception system in which the extracorporeal unit has a planar conductor arranged so as to cover the outside of a position where the magnetic current antenna constituting the extracorporeal unit is arranged with respect to the living body. A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
Each of the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit is within the plane perpendicular to the direction of the magnetic field formed at the center of the magnetic current type antenna. The ratio of the magnetic field to the electric field formed by the magnetic current antenna has a characteristic of increasing as it approaches the magnetic current antenna,
A radio capsule transmission / reception system in which the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit are configured by a loop antenna, a microstrip antenna, or a plate-like inverted F antenna. A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
Each of the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit is within the plane perpendicular to the direction of the magnetic field formed at the center of the magnetic current type antenna. The ratio of the magnetic field to the electric field formed by the magnetic current antenna has a characteristic of increasing as it approaches the magnetic current antenna,
The extracorporeal unit is a radio capsule transmission / reception system arranged in a corset or clothes. The radio capsule transmission / reception system according to claim 1 or 2 , wherein the planar conductor is disposed on a corset or clothes. The radiocapsule transmission / reception system according to claim 1 or 2 , wherein the planar conductor is made of a conductive fabric woven from conductive fibers. The radio capsule transmission / reception system according to claim 4 , wherein the magnetic current type antenna of the extracorporeal unit is arranged to be removable from the corset or the clothes. The radio capsule transmission / reception system according to claim 5 , wherein a desorption mechanism is provided on the corset or the clothes and the planar conductor. The radio capsule transmission / reception according to claim 5 , wherein a cable that connects the magnetic current type antenna constituting the extracorporeal unit and the transmission / reception unit or the reception unit is routed to the living body outside the corset or the clothes. system. The radio capsule transmission / reception system according to claim 5 , wherein a cable connecting the magnetic current type antenna constituting the extracorporeal unit and the transmission / reception unit or the reception unit is routed inside the planar conductor as viewed from the living body. . A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
Each of the magnetic current type antenna incorporated in the radio capsule and the magnetic current type antenna of the extracorporeal unit is within the plane perpendicular to the direction of the magnetic field formed at the center of the magnetic current type antenna. The ratio of the magnetic field to the electric field formed by the magnetic current antenna has a characteristic of increasing as it approaches the magnetic current antenna,
The ratio of the magnetic field to the electric field exponentially increases as the magnetic current antenna is approached in the region from the center of the magnetic current antenna to 0.3 times the wavelength of the radiation wave of the magnetic current antenna. to Lula Geo capsule transmitting and receiving system. A radio capsule having a sensor that is introduced into a living body to detect biological information, and a transmitter that transmits the biological information detected by the sensor using a magnetic current antenna;
An external unit having a magnetic current type antenna for receiving a signal transmitted from the magnetic current type antenna of the radio capsule;
The extracorporeal unit is disposed in a garment;
The magnetic current type antenna is a loop antenna disposed on the ventral side when the extracorporeal unit is attached to the living body,
The extracorporeal unit is located on the back side when the extracorporeal unit is attached to the living body and a first planar conductor disposed so as to cover the loop antenna outside the loop antenna when viewed from the living body. A radiocapsule transmission / reception system further comprising a second planar conductor disposed.

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