JP2005304511A - Position detecting apparatus and position in subject detecting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a position in a subject detecting system which does not consume much electric power and can precisely detect a position of an introduced apparatus in a subject. <P>SOLUTION: The position in the subject detecting system includes a test capsule 2 which is introduced in the subject 1 and functions as an example of the introduced apparatus in the subject, a position detecting apparatus 3 which detects the position of the test capsule 2 in the subject 1, a display apparatus 4 to display the positional information of the test capsule 2 detected by the position detecting apparatus 3, and a portable recording medium 5 which executes a delivery of the information between the position detecting apparatus 3 and the display apparatus 4, wherein the test capsule 2 has a function to form a magnetic field of which the element in the vertical direction changes according to a prescribed cycle, magnetic field detecting apparatuses 6a-6h which are installed in the position detecting apparatus 3 have mechanisms to detect the magnetic field intensity in the vertical direction, and a positional information derivation apparatus 8 is constituted to extract a frequency element corresponding to the cycle of the magnetic field formed by the test capsule 2 and to execute the position detecting. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a position detection device that detects the position of an in-subject introduction device that is introduced into a subject and forms a magnetic field component in the vertical direction at least periodically, and a technique using the position detection device.

  In recent years, in the field of endoscopes, swallowable capsule endoscopes have been proposed. This capsule endoscope is provided with an imaging function and a wireless communication function. The capsule endoscope is swallowed from the mouth of the subject for observation (examination) until it is spontaneously discharged until it is spontaneously discharged. It has the function of moving and capturing images sequentially.

  While moving inside the body cavity, image data captured inside the body by the capsule endoscope is sequentially transmitted to the outside by wireless communication and stored in a memory provided outside. By carrying a receiver having a wireless communication function and a memory function, the subject can freely act after swallowing the capsule endoscope and before being discharged. After the capsule endoscope is ejected, the doctor or nurse can make a diagnosis by displaying an image of the organ on the display based on the image data stored in the memory.

  With regard to such a capsule endoscope, for example, in order to capture an endoscopic image of a specific organ inside the subject, a function for detecting the position of the capsule endoscope in the subject is provided on the receiver side. Has been proposed. As an example of a capsule endoscope system having such a position detection function, a capsule endoscope system that utilizes a wireless communication function built in the capsule endoscope is known. In other words, the receiver provided outside the subject has a configuration including a plurality of antenna elements, and the radio signals transmitted from the capsule endoscope are received by the individual antenna elements, and received by the respective antenna elements. It has a mechanism for detecting the position of the capsule endoscope in the subject based on the difference in intensity (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-19111

  However, when the position of the capsule endoscope in the conventional capsule endoscope system is detected, the power consumption of the capsule endoscope increases and the pointing direction of the capsule endoscope changes. It had the subject that detection accuracy fell. Hereinafter, this problem will be described.

  That is, in the conventional capsule endoscope system, the wireless communication function built in the capsule endoscope is used for position detection. For this reason, in the conventional capsule endoscope system, it is necessary to perform a wireless communication operation every time position detection is performed, and power consumption is increased as compared with a normal capsule endoscope.

  Further, as a configuration similar to the capsule endoscope system, an in-subject introduction system using a test capsule instead of the capsule endoscope has been proposed. Such a system is for determining whether or not there is a stenosis or the like in a body cavity of a subject prior to introducing the capsule endoscope into the subject. Unlike this, a test capsule that does not have an imaging function is used. If the test capsule is discharged from the body, it is determined that there is no stenosis.

  Even in the case of a system using such a test capsule, it is required to realize a mechanism for detecting the position in the subject. However, in the case of the above-described conventional technique, a new wireless communication function is provided for position detection. In addition, there is a need to provide a power supply mechanism for wireless communication. Such a structure leads to an increase in the manufacturing cost of the test capsule and is not appropriate.

  Furthermore, the conventional capsule endoscope system has a problem in terms of position detection accuracy. That is, the wireless communication function built in the capsule endoscope normally has a configuration in which a wireless signal is transmitted in a direction fixed with respect to the capsule endoscope. Therefore, the reception sensitivity of the external receiver changes as the direction of the capsule endoscope in the subject changes. That is, the strength of the radio signal received by the receiver does not necessarily correspond to the distance from the capsule endoscope, and the position detection accuracy is improved when position detection is performed using a conventional method. The problem is not necessarily high.

  The present invention has been made in view of the above, and in a state where an intra-subject introduction apparatus such as a capsule endoscope is introduced into the subject, low power consumption and position detection of the intra-subject introduction apparatus It is an object of the present invention to realize an in-subject position detection system capable of accurately performing the above.

  In order to solve the above-described problems and achieve the object, a position detection device according to claim 1 is introduced into a subject, and the position of the in-subject introduction device which forms a magnetic field component in the vertical direction at least periodically. A magnetic field detection means for detecting the magnetic field strength in the vertical direction, a storage means for storing a correspondence relationship between the magnetic field strength and the distance from the in-subject introduction device, and the magnetic field detection means. A distance deriving unit for deriving a distance between the magnetic field detecting unit and the in-subject introduction device based on the magnetic field intensity detected by the storage unit and the correspondence relationship stored in the storage unit; and the distance deriving unit And a position deriving means for deriving the position of the in-subject introduction device based on the deriving result by the method.

  According to the first aspect of the present invention, since the position detection is performed using the magnetic field detection means for detecting the magnetic field component in the vertical direction, it is possible to detect the strength of the magnetic field component excluding the influence of the geomagnetism. The magnetic field formed by the in-subject introduction device can be detected while avoiding the detection of a noise magnetic field such as a geomagnetic component. For this reason, position detection can be performed with high accuracy without being affected by noise components such as geomagnetism.

  According to a second aspect of the present invention, in the above-described invention, a plurality of the magnetic field detection units are arranged at predetermined positions on the subject, and the position derivation unit includes the plurality of magnetic field detection units and the target. The position of the intra-subject introduction device is derived based on the distance from the intra-specimen introduction device.

The position detection device according to claim 3 is a position detection device that detects the position of the in-subject introduction device that is introduced into the subject and at least periodically forms a vertical magnetic field component,
Magnetic field detection means for detecting the magnetic field strength in the vertical direction, and position derivation for deriving whether or not the in-subject introduction apparatus is located outside the subject based on the magnetic field strength detected by the magnetic field detection means Means.

  According to the third aspect of the invention, since the in-subject introduction apparatus is provided with the position deriving means for determining whether or not the in-subject introduction apparatus is located in the subject based on the detected magnetic field strength, for example, introduction into the subject It is possible to easily measure the time required for the apparatus to pass through the subject.

  According to a fourth aspect of the present invention, there is provided the position detecting device according to the above invention, wherein the position deriving unit is configured to introduce the in-subject introducing device when the intensity of the magnetic field detected by the magnetic field detecting unit is less than a predetermined threshold value. Is determined to be located outside the subject.

  According to the fourth aspect of the invention, the position deriving means determines the position by comparing the detected magnetic field strength value with the predetermined threshold value, so that a position detecting device with a simple configuration is realized. Can do.

  According to a fifth aspect of the present invention, there is provided the position detection apparatus according to the above invention, wherein the in-subject introduction apparatus forms a magnetic field whose intensity in the vertical direction changes periodically and is detected by the magnetic field detection means. The magnetic field component further includes component extraction means for extracting a frequency component corresponding to the period of the magnetic field formed by the in-subject introduction device.

  According to a sixth aspect of the present invention, in the above invention, the component extraction unit includes a band filter unit that allows a frequency component corresponding to a period of a magnetic field formed by the in-subject introduction device to pass therethrough. It is characterized by that.

  According to a seventh aspect of the present invention, in the above-described invention, the component extraction unit includes a lock-in amplifier that detects a frequency component corresponding to a period of a magnetic field formed by the in-subject introduction device. It is characterized by that.

  In addition, an in-subject position detection system according to claim 8 is introduced into a subject and moves inside the subject, and is placed outside the subject, and the inside of the subject An intra-subject position detection system including a position detection device that acquires position information of the intra-subject introduction device, wherein the intra-subject introduction device forms a magnetic field component in the vertical direction at least periodically. The position detection device includes: a magnetic field detection unit that detects a magnetic field component in a vertical direction; a storage unit that stores a correspondence relationship between a magnetic field strength and a distance from the in-subject introduction device; and the magnetic field detection unit. Distance deriving means for deriving a distance between the magnetic field detecting means and the in-subject introduction device based on the magnetic field intensity detected by the storage means and the correspondence relationship stored in the storage means, and the distance deriving means Based on the derived result by, characterized in that a position deriving means for deriving a position of the body-insertable apparatus.

  In addition, an in-subject position detection system according to claim 9 is introduced into a subject and moves inside the subject, and is placed outside the subject, and the inside of the subject is placed inside the subject. An intra-subject position detection system including a position detection device that acquires position information of the intra-subject introduction device, wherein the intra-subject introduction device forms a magnetic field component in the vertical direction at least periodically. The position detection device includes: a magnetic field detection unit configured to detect a magnetic field component in a vertical direction; and the in-subject introduction device is disposed outside the subject based on the intensity of the magnetic field detected by the magnetic field detection unit. Position deriving means for deriving whether or not it is located is provided.

  The in-subject position detection system according to claim 10 is the above-described invention, wherein the in-subject introduction device includes an in-subject information acquisition unit that acquires the in-subject information, and the in-subject information acquisition. Wireless transmission means for wirelessly transmitting the in-subject information acquired by the means, wherein the position detecting device receives a wireless signal including the in-subject information transmitted from the wireless transmission means. Is further provided.

  An in-subject position detection system according to an eleventh aspect of the present invention is the above invention, wherein a plurality of the receiving means are arranged, and the position detecting device is the position of the in-subject introducing device derived by the position information deriving means. The apparatus further comprises selection means for selecting the receiving means used for receiving the radio signal based on the position.

  The in-subject position detection system according to claim 12 is the above-described invention, wherein the in-subject information acquisition unit includes an illuminating unit that irradiates the inside of the subject, and the subject that is irradiated by the illuminating unit. And an image pickup means for acquiring the image inside.

  In the in-subject position detection system according to claim 13, in the above invention, the position detection device includes an image acquired by the imaging unit, and a position of the in-subject introduction apparatus at the time of acquiring the image. Is further provided with storage means for storing the information in association with each other.

  Since the position detection apparatus and the in-subject position detection system according to the present invention perform position detection using the magnetic field detection means for detecting the magnetic field component in the vertical direction, the intensity of the magnetic field component that excludes the influence of geomagnetism is detected. This makes it possible to detect the magnetic field formed by the in-subject introduction device while avoiding detection of a noise magnetic field such as a geomagnetic component. For this reason, the position detection can be performed with high accuracy without being affected by noise components such as geomagnetism.

  In addition, the position detection device and the in-subject position detection system according to the present invention include position derivation means for determining whether or not the in-subject introduction device is located in the subject based on the detected magnetic field strength. Therefore, for example, it is possible to easily measure the time required for the intra-subject introduction apparatus to pass through the subject.

  The position detection device according to the present invention realizes a position detection device with a simple configuration because the position deriving means determines the position by comparing the detected magnetic field strength value with a predetermined threshold value. There is an effect that can be.

  The in-subject position detection system that is the best mode for carrying out the present invention will be described below. Note that the drawings are schematic, and it should be noted that the relationship between the thickness and width of each part, the ratio of the thickness of each part, and the like are different from the actual ones. Of course, the part from which the relationship and ratio of a mutual dimension differ is contained.

(Embodiment 1)
First, the in-subject position detection system according to the first embodiment will be described. As shown in FIG. 1, the in-subject position detection system according to the first embodiment is introduced into the subject 1 and functions as an example of an in-subject introduction apparatus, and the test capsule 2. A position detection device 3 that detects the position of the subject 1 inside the subject 1, a display device 4 that displays position information of the test capsule 2 detected by the position detection device 3, and between the position detection device 3 and the display device 4. And a portable recording medium 5 for transferring the information.

  The display device 4 is for displaying the position information of the test capsule 2 acquired by the position detection device 3, such as a workstation that displays an image based on data obtained by the portable recording medium 5. It has a configuration. Specifically, the display device 4 may be configured to directly display an image by a CRT display, a liquid crystal display, or the like, or may be configured to output an image to another medium such as a printer.

  The portable recording medium 5 is detachable with respect to a position information deriving device 8 and a display device 4 described later, and has a structure capable of outputting and recording information when being inserted into both. Specifically, the portable recording medium 5 is inserted into the position information deriving device 8 and records information on the position of the test capsule 2 while the test capsule 2 is moving in the body cavity of the subject 1. Then, after the test capsule 2 is discharged from the subject 1, it is taken out from the position information deriving device 8 and inserted into the display device 4, and the recorded data is read out by the display device 4. Data is transferred between the position information deriving device 8 and the display device 4 by a portable recording medium 5 such as a compact flash (registered trademark) memory, so that the position information deriving device 8 and the display device 4 are wired. Unlike the case in which the test capsule 2 is connected, the subject 1 can freely move even when the test capsule 2 is moving inside the subject 1.

  Prior to introducing the capsule endoscope or the like into the subject 1, the test capsule 2 determines whether or not there is a stenosis or the like that is difficult for the capsule endoscope to pass through in the subject 1. It is used when performing inspection. That is, the in-subject position detection system according to the first embodiment is for examining how the test capsule 2 moves in the subject 1, and is highly accurate to achieve this purpose. The position detection mechanism is provided.

  FIG. 2 is a schematic diagram showing the structure of the test capsule 2. As shown in FIG. 2, the test capsule 2 includes a casing 11 having a capsule shape similar to that of a capsule endoscope, a case member 12 disposed inside the casing 11, and an inner surface of the casing 11. And a filling member 13 that functions as a member that fills a gap between the case member 12 and the case member 12.

  The housing 11 is formed of, for example, a biocompatible material, and has a characteristic that it is decomposed when it stays in the subject 1 for several days.

  The filling member 13 is for filling the space between the inner surface of the housing 11 and the case member 12 and fixing the position of the case member 12. The material forming the filling member 13 does not adversely affect the subject 1, and the filling member 13 is formed of, for example, barium sulfate. Since barium sulfate can be used as a contrast agent in X-ray examination, position detection by X-ray examination is possible in addition to position detection in the first embodiment, and by comparing the detection results of both, It is possible to perform more accurate position detection. In the first embodiment, it is not essential to use barium sulfate as the filling member 13, and it is needless to say that any member can be used as long as it functions as the filling member.

  The case member 12 includes a mechanism for generating a magnetic field in the vertical direction. Specifically, the inside of the case member 12 is formed in a hollow shape, the liquid 14 is sealed inside the case member 12, and the spherical shell member 15 is arranged in a state of floating in the liquid 14. Yes. Inside the spherical shell member 15, a drive mechanism 16 for causing a predetermined rotational movement, a magnetic field forming unit 17, and permanent magnets 17a and 17b for forming a predetermined magnetic field, and a drive A shaft member 18 for transmitting torque supplied from the mechanism 16 to the permanent magnets 17a and 17b is disposed.

  The drive mechanism 16 is for rotating the permanent magnets 17a and 17b via the shaft member 18, and is constituted by a predetermined battery and an electric motor, for example. The drive mechanism 16 is disposed in a state of being fixed on the inner surface of the spherical shell member 15, has a predetermined weight, and also has a function as a weight member with respect to the spherical shell member 15. That is, the spherical shell member 15 is arranged so as to float in the liquid 14, and the directing direction of the spherical shell member 15 and the components in the spherical shell member 15 is stabilized by the drive mechanism 16 having a predetermined weight. I am letting. Specifically, when the drive mechanism 16 functions as a weight member, the longitudinal direction of the shaft member 18 and the permanent magnets 17a and 17b is always substantially aligned with the vertical direction regardless of variations in the direction of the test capsule 2. Will be maintained.

  The shaft member 18 is for transmitting the torque supplied from the drive mechanism 16 to the permanent magnets 17a and 17b. Specifically, as shown in FIG. 2, the shaft member 18 has a mechanism that rotates in the direction indicated by the arrow with the longitudinal direction as the rotation axis.

  The permanent magnets 17 a and 17 b are for forming a magnetic field used when detecting the position of the test capsule 2. Specifically, each of the permanent magnets 17a and 17b is formed by a bar magnet or the like that forms a static magnetic field, and is configured to rotate in a state in which the longitudinal direction always coincides with the vertical direction based on the action of the drive mechanism 16. Yes. That is, when the drive mechanism 16 functions as a weight member, the longitudinal direction of the permanent magnets 17a and 17b is always maintained in a state substantially coincident with the vertical direction, and by the torque supplied from the drive mechanism 16, the permanent magnets 17a and 17b Thus, a rotational motion is performed with the longitudinal direction (vertical direction) of the shaft member 18 as the rotational axis.

  Note that the permanent magnets 17a and 17b are arranged in a state of being fixed to each other, and are configured to rotate together in the case of a rotational movement. Here, the reason why the permanent magnets 17a and 17b are provided is to vary the strength of the magnetic field component in the vertical direction in the magnetic field supplied to the outside in accordance with the period accompanying the rotational motion. That is, by arranging the permanent magnet 17b, the strength of the magnetic field around the rotation axis becomes higher than the others in the direction corresponding to the position of the permanent magnet 17b. For this reason, in the first embodiment, the permanent magnets 17a and 17b are caused to rotate about the longitudinal direction of the shaft member 18 as the rotation axis, so that the magnetic field strength detected outside corresponds to the rotation period. Periodic fluctuations are given.

  Next, the position detection device 3 will be described. The position detection device 3 is for detecting the position of the test capsule 2 inside the subject 1 based on the magnetic field formed by the test capsule 2. Specifically, as shown in FIG. 1, the position detection device 3 includes magnetic field detection devices 6 a to 6 h that detect the strength of the magnetic field formed by the test capsule 2 and the magnetic field detection devices 6 a to 6 d on the subject 1. The position of the test capsule 2 is determined based on the fixing member 7a to be fixed, the fixing member 7b for fixing the magnetic field detection devices 6e to 6h to the subject 1, and the magnetic field intensity detected by the magnetic field detection devices 6a to 6h. And a position information deriving device 8 for deriving.

  The magnetic field detection devices 6a to 6h are for detecting the magnetic field strength at the place where each is arranged. FIG. 3 is a schematic diagram showing a specific configuration of each of the magnetic field detection devices 6a to 6h. As illustrated in FIG. 3, the magnetic field detection devices 6 a to 6 h include a spherical body 22 including a magnetic field sensor unit 24 and a liquid arranged to cover the outer surface of the spherical body 22 in order to hold the spherical body 22 in a floating state. 23, a case member 21 for holding the liquid 23, and components provided outside the case member 21.

  The spherical body 22 includes a magnetic field sensor unit 24, a magnetic field measurement system control unit 25 that controls the driving state of the magnetic field sensor unit 24, and modulation and signal modulation as necessary when performing wireless communication with the outside of the spherical body 22. A transmission / reception unit 28 for performing demodulation and a transmission / reception antenna 29 for performing wireless communication with the outside are provided. The spherical body 22 includes a battery 26 that holds power for driving the magnetic field sensor unit 24 and the like, a power receiving unit 27 that converts a power feeding signal transmitted from an external power feeding antenna 32 (described later), and power from the outside. And a power receiving antenna 30 for receiving a power feeding signal to be transmitted and supplying the power feeding unit to the power receiving unit.

  Furthermore, the spherical body 22 includes a weighting member 31 that is disposed on an extension of the magnetic field detection direction (described later) of the magnetic field sensor unit 24 and is heavier than other components. Since the spherical body 22 is held in a state of floating in the liquid 23, the weight member 31 always has the bottom portion in the vertical downward direction by the action of the weight member 31 regardless of the change in the state of the magnetic field detection device 6. Maintain the position located at.

  The magnetic field sensor unit 24 includes a magnetic field intensity detection sensor such as an MI sensor having a function of detecting a magnetic field traveling in a predetermined direction (hereinafter, this magnetic field direction is referred to as “magnetic field detection direction”). For example, the MI sensor has a configuration using, for example, an FeCoSiB amorphous wire as a magnetosensitive medium, and when a high frequency current is applied to the magnetosensitive medium, the magnetic impedance of the magnetosensitive medium greatly changes due to an external magnetic field. Magnetic field strength is detected using the MI effect. The magnetic field sensor unit 24 includes a magnetic field detection direction indicated by an arrow in FIG. 3 and has a configuration in which the weight member 31 is disposed on an extension of the magnetic field detection direction. The detection direction is always maintained in a state in which the vertical direction coincides with the vertical direction. Among the magnetic fields existing in the region where the magnetic field detection device 6 is disposed, the intensity of the magnetic field component traveling in the vertical direction is detected. Thus, an electric signal having an intensity corresponding to is output.

  The magnetic field detection device 6 is disposed near the outside of the case member 21, and transmits / receives an electric signal corresponding to the magnetic field strength detected by the magnetic field sensor unit 24 and a power feeding antenna 32 that transmits a power feeding signal. An antenna 33, a power supply unit 34 electrically connected to the power supply antenna 32, and a transmission / reception unit 35 electrically connected to the transmission / reception antenna 33 are provided. The power supply unit 34 and the transmission / reception unit 35 are electrically connected to the control unit 36 and operate under the control of the control unit 36. The control unit 36 is electrically connected to the position information deriving device 8, operates based on the control by the position information deriving device 8, and transmits the magnetic field intensity detected by the magnetic field sensor unit 24 to the position information deriving device 8. It has the function to output it.

  The fixing members 7 a and 7 b are for fixing the magnetic field detection devices 6 a to 6 h to the subject 1. Specifically, the fixing members 7 a and 7 b are formed in an annular shape by, for example, an elastic member, and have a configuration in which the fixing members 7 a and 7 b are fixed in close contact with the body of the subject 1. The magnetic field detection devices 6a to 6d and the magnetic field detection devices 6e to 6h are fixed to predetermined positions with respect to the subject 1 by fixing members 7a and 7b, respectively, and the fixing members 7a and 7b are attached to the body of the subject 1. By tightly fixing, the magnetic field detection devices 6a to 6h are arranged in a state where the relative position with respect to the subject 1 is fixed.

  Next, the position information deriving device 8 will be described. The position information deriving device 8 extracts the strength of the magnetic field formed by the test capsule 2 from the magnetic field strength detected by the magnetic field detecting devices 6a to 6h, and derives the position of the test capsule 2 based on the extracted magnetic field strength. belongs to.

  FIG. 4 is a block diagram showing the configuration of the position information deriving device 8. As shown in FIG. 4, the position information deriving device 8 includes a band filter unit 39 for allowing a predetermined frequency component to pass through the electrical signals obtained by each of the magnetic field detection devices 6 a to 6 h according to the detected magnetic field strength. An A / D converter 40 that performs analog / digital conversion of the electrical signal that has passed through the band filter unit 39, and a lock-in amplifier 41 for extracting a predetermined frequency component from the electrical signal converted into digital data With. The position information deriving device 8 is a distance deriving unit for deriving the distance between the test capsule 2 and each of the magnetic field detecting devices 6a to 6h based on the intensity of the electrical signal extracted by the lock-in amplifier unit 41. 42, a correspondence database 43 that stores correspondence data used when the distance deriving unit 42 derives the distance, and a position deriving unit 44 that calculates the position of the test capsule 2 based on the distance derived by the distance deriving unit 42 And a storage unit 45 for storing the position of the test capsule 2 obtained by the position deriving unit 44.

  The band filter unit 39 is for excluding the magnetic field components formed by the magnetic field forming unit 17 from the vertical magnetic field components detected by the magnetic field detection devices 6a to 6h. Specifically, the band filter unit 39 has a function of cutting signals other than frequency components corresponding to the rotation frequency of the magnetic field forming unit 17 with respect to the electric signals input from the magnetic field detection devices 6 a to 6 h.

  The lock-in amplifier unit 41 has a function of extracting only a predetermined frequency component from the digital signal converted by the A / D conversion unit 40 and outputting it to the distance deriving unit 42. Specifically, the lock-in amplifier unit 41 has a function of extracting a frequency component that substantially matches the rotational frequency of the magnetic field forming unit 17 from the input electric signal and outputting the frequency component to the distance deriving unit 42. Specifically, the lock-in amplifier unit 41 may be realized by installing a predetermined program in an electric computer such as a PC, or may be realized by a hardware configuration.

  As described above, since the magnetic field forming unit 17 rotates at a predetermined cycle by the action of the driving mechanism 16, the intensity of the vertical magnetic field component formed by the magnetic field forming unit 17 changes according to the predetermined cycle. Become. In the first embodiment, based on such characteristics of the magnetic field formed by the magnetic field forming unit 17, noise components generated from other than the magnetic field forming unit 17 are removed by the band filter unit 39 and the lock-in amplifier unit 41, and the magnetic field The distance derivation by the distance deriving unit 42 is performed using only the electrical signal based on the magnetic field formed by the forming unit 17. In the first embodiment, both the band filter unit 39 and the lock-in amplifier unit 41 are provided. However, at least theoretically, the noise component may be removed by only one of them.

The correspondence database 43 stores in advance the correspondence between the strength of the magnetic field formed by the test capsule 2 and the distance from the test capsule 2, and outputs the stored information to the distance deriving unit 42. Is. Specifically, the correspondence database 43 stores, for example, the value of the distance L _j corresponding to the value of the electric signal intensity P _j (j: natural number) according to the magnetic field intensity.

The distance deriving unit 42, based on the intensity of the magnetic field detected in each of the magnetic field detection devices 6 a to 6 h and the information stored in the correspondence database 43, each of the magnetic field detection devices 6 a to 6 h and the test capsule 2. It is for deriving the distance between. That is, the distance deriving unit 42 inputs an electrical signal corresponding to the magnetic field component in the vertical direction detected in each of the magnetic field detection devices 6a to 6h, and is input among the information stored in the correspondence database 43. The intensity P _j closest to the intensity of the electric signal is searched, and for example, a distance L _j corresponding to the searched magnetic field intensity is derived as a distance between the magnetic field detection device and the test capsule 2.

  The position deriving unit 44 derives the position of the test capsule 2 in the subject 1 based on the distance between each of the magnetic field detection devices 6 a to 6 h and the test capsule 2 derived by the distance deriving unit 42. belongs to. Specifically, the position deriving unit 44 uses predetermined positions of the magnetic field detection devices 6a to 6h on the subject 1 and the distance value derived by the distance deriving unit 42 to perform predetermined calculation processing. By doing this, the position of the test capsule 2 is derived.

  The storage unit 45 is for storing the position of the test capsule 2 derived by the position deriving unit 44. Specifically, the storage unit 45 has a function of storing predetermined information in the portable recording medium 5 shown in FIG. 1, and the storage unit 45 stores the position information of the test capsule 2 in the portable recording medium 5. Is remembered.

  Next, the operation of the in-subject position detection system according to the first embodiment will be described. In the first embodiment, the magnetic field forming unit 17 provided in the test capsule 2 rotates at a predetermined angular velocity while maintaining the state in which the longitudinal direction (the output direction of the lines of magnetic force) matches the vertical direction by the action of the drive mechanism 16. The magnetic field of the state is formed. Since the magnetic field forming unit 17 has a configuration in which the permanent magnet 17b is fixed to the permanent magnet 17a, the intensity of the vertical component of the magnetic field formed by the magnetic field forming unit 17 changes according to the period according to the rotation operation. Will be. The in-subject position detection system according to the first embodiment detects the position of the test capsule 2 according to the following operation based on the magnetic field.

  First, the magnetic field detection devices 6a to 6h detect a magnetic field in the vertical direction including the magnetic field formed by the magnetic field forming unit 17 (step S101), and send an electric signal having an intensity corresponding to the detected intensity to the position information deriving device 8. Output. With respect to such an electrical signal, the position information deriving device 8 removes a noise component unrelated to the magnetic field formed by the magnetic field forming unit 17 by both the band filter unit 39 and the lock-in amplifier unit 41 (step S102), and removes the noise component. The removed electrical signal is output to the distance deriving unit 42.

  Then, the distance deriving unit 42 searches for the correspondence recorded in the correspondence database 43 based on the strength of the input electrical signal (step S103), and the strength of the electrical signal for each of the magnetic field detection devices 6a to 6h. A distance value corresponding to is derived (step S104), and the derivation result is output to the position deriving unit 44. On the other hand, the position deriving unit 44 is based on the distance from the test capsule 2 derived for each of the magnetic field detection devices 6a to 6h and the position information on the subject 1 of the magnetic field detection devices 6a to 6h. The position of the test capsule 2 is derived (step S105), and the derived result is stored in the portable recording medium 5 via the storage unit 45. Such an operation is repeated until the test capsule 2 is discharged to the outside of the subject 1, and the portable recording medium 5 stores the position of the test capsule 2 at each time. Thereafter, the portable recording medium 5 is ejected from the position information deriving device 8 and attached to the display device 4, and doctors, nurses, and the like can check the inside of the subject 1 based on the information displayed on the screen of the display device 4. The content of the change in position of the test capsule 2 is grasped.

  In step S <b> 105, the position of the test capsule 2 is derived based on the distance between the position of the magnetic field detection devices 6 a to 6 h and the test capsule 2. Here, when the position of the test capsule 2 is represented by an orthogonal coordinate system, there are three unknowns necessary for derivation of the position, that is, the x coordinate, the y coordinate, and the z coordinate of the test capsule 2. Accordingly, the number of magnetic field detection devices 6 that are theoretically necessary is sufficient, but in the first embodiment, the position variation of the magnetic field detection device accompanying the posture change of the subject 1 is taken into consideration. The calculation using the six magnetic field detection devices 6 is performed, and the fluctuation range of the x-coordinate, y-coordinate, and z-coordinate values of the test capsule 2 derived by the equations relating to the magnetic field detection devices 6a to 6h is the smallest. As described above, the position coordinates and the like of the magnetic field detection devices 6a to 6h are corrected using the maximum likelihood method or the like.

  Next, advantages of the in-subject position detection system according to the first embodiment will be described. First, the in-subject position detection system according to the first embodiment has a configuration in which position detection is performed using a magnetic field formed by the magnetic field forming unit 17 provided in the test capsule 2. For this reason, the test capsule 2 does not need to include a wireless transmission mechanism for position detection, and has an advantage that position detection can be performed in the test capsule 2 without power consumption.

  In the in-subject position detection system according to the first embodiment, the magnetic field forming unit 17 held in the test capsule 2 has the magnetic field direction parallel to the vertical direction regardless of the change in the directing direction of the test capsule 2. Maintain the state. Further, the magnetic field sensor unit 24 held in the magnetic field detection devices 6a to 6h maintains a state in which the magnetic field detection direction is parallel to the vertical direction, regardless of changes in the posture of the subject 1 or the like. For this reason, in the in-subject position detection system according to the first embodiment, the magnetic field output direction by the magnetic field forming unit 17 and the magnetic field detection direction of the magnetic field sensor unit 24 are always kept in parallel.

  By adopting such a configuration, the in-subject position detection system according to the first embodiment has the advantage that highly sensitive magnetic field strength detection is possible. That is, most of the magnetic field formed by the magnetic field forming unit 17 proceeds in the direction parallel to the magnetic field output direction even outside the subject 1, so the magnetic field detection direction of the magnetic field sensor unit 24 is the magnetic field forming unit 17. It becomes possible to efficiently detect the magnetic field formed by the magnetic field forming unit 17 and to detect the magnetic field intensity with high sensitivity.

  In addition, the in-subject position detection system according to the first embodiment can simplify the configuration of the magnetic field sensor unit particularly with respect to the magnetic field detection devices 6a to 6h. That is, when the magnetic field output direction from the magnetic field forming unit 17 and the magnetic field detection direction of the magnetic field sensor unit do not have a correlation, the magnetic field detection device needs to include a magnetic field intensity detection mechanism in the three-axis directions. In general, it is necessary to provide a magnetic field sensor unit having a magnetic field detection direction with respect to each of the x direction, the y direction, and the z direction. In contrast, the in-subject position detection system according to the first embodiment is arranged in a state in which the magnetic field detection direction of the magnetic field sensor unit 24 matches the magnetic field output direction of the magnetic field forming unit 17. A detection mechanism having a magnetic field detection function only in one direction can be used, and the configuration of the magnetic field detection mechanism can be simplified.

  Further, the in-subject position detection system according to the first embodiment has an advantage that the influence of the geomagnetic component can be eliminated. That is, the magnetic field output direction from the magnetic field forming unit 17 is the vertical direction, and the magnetic field strength detection devices 6a to 6h have a function of detecting the strength of the magnetic field component in the vertical direction. On the other hand, since the geomagnetic component travels in a direction substantially perpendicular to the vertical direction, that is, in a substantially horizontal direction with respect to the ground, the magnetic field strength detection devices 6a to 6h inherently detect the strength of the geomagnetic component. Rather, it is possible to eliminate the influence of the geomagnetic component at the time of position detection.

  Further, the first embodiment is configured such that the intensity of the magnetic field formed by the test capsule 2 changes at a period corresponding to the rotation period of the magnetic field forming unit 17. For this reason, there is a difference in frequency between the magnetic field formed by the test capsule 2 and the noise magnetic field, and the position information deriving device 8 can extract only the magnetic field from the test capsule 2 based on the difference. Yes. That is, in the first embodiment, the electric signal corresponding to the detected magnetic field input from the magnetic field detection devices 6a to 6h is set to the rotation period of the magnetic field forming unit 17 by both the band filter unit 39 and the lock-in amplifier unit 41. A configuration for extracting only the corresponding frequency components is adopted. By adopting such a configuration, the distance deriving unit 42 included in the position information deriving device 8 removes noise components, and uses high-precision distance deriving using only electrical signals corresponding to the magnetic field components formed by the test capsule 2. Has the advantage of becoming possible.

(Embodiment 2)
Next, the in-subject position detection system according to the second embodiment will be described. In the in-subject position detection system according to the second embodiment, as a simpler configuration, the position deriving unit does not derive the specific position of the test capsule 2, but the test capsule 2 is located in the subject. Whether or not is determined.

  For example, one of the purposes for introducing the test capsule 2 into the subject 1 is to measure the time required for the test capsule 2 to pass through the subject 1. When the test capsule 2 is used based on such a purpose, it is very important to know when the test capsule 2 is discharged out of the subject 1. For this reason, in the second embodiment, it is determined whether or not the test capsule 2 is located in the subject 1, and this objective can be sufficiently achieved and an in-subject position detection system with a simple configuration is realized. doing.

  FIG. 6 is a block diagram showing a configuration of the position information deriving device 46 provided in the in-subject position detection system according to the second embodiment. The in-subject position detection system according to the second embodiment includes a test capsule 2, a display device 4, a portable recording medium 5, a magnetic field detection device 6, and the like, as in the first embodiment. Since these components are exactly the same as those in the first embodiment, illustration and description are omitted in the second embodiment, and hereinafter, a position information deriving device that is different from the first embodiment. 46 will be mainly described.

  As shown in FIG. 6, the position information deriving device 46 includes a band filter unit 39, an A / D conversion unit 40, a lock-in amplifier unit 41, and a storage unit 45 as in the first embodiment. Is provided with a position deriving unit 47 that determines whether or not the object is located in the subject 1.

  Next, the operation of the in-subject position detection system according to the second embodiment will be described focusing on the operation of the position deriving unit 47. FIG. 7 is a flowchart showing the operation of the in-subject position detection system according to the second embodiment. Hereinafter, the operation will be described with reference to FIG.

  First, an electric signal corresponding to the detected magnetic field in the vertical direction is output by the magnetic field detection device 6 (step S201), and the position information deriving device 46 has a magnetic field provided in the test capsule 2 by the band filter unit 39 and the lock-in amplifier unit 41. Noise components unrelated to the magnetic field formed by the forming unit 17 are removed (step S202). Thereafter, the position deriving unit 47 determines whether or not the intensity of the electrical signal from which the noise component has been removed is equal to or greater than a predetermined threshold (step S203).

  When it is determined that the intensity of the electrical signal from which the noise component has been removed is equal to or greater than the threshold (Yes at Step S203), the position deriving unit 47 determines that the test capsule 2 is located inside the subject 1 (Step S204). finish. On the other hand, when it is determined that the intensity of the electrical signal from which the noise component has been removed is less than the threshold value (No in step S203), the position deriving unit 47 determines that the test capsule 2 has been discharged to the outside of the subject 1. (Step S205) and the process ends. The above operation is repeated until it is determined that the test capsule 2 has been discharged to the outside of the subject 1, and the determination result is stored in the portable recording medium 5 via the storage unit 45.

  The determination in step S203 is performed based on the following mechanism. The magnetic field formed by the magnetic field forming unit 17 provided in the test capsule 2 has a characteristic of decaying according to the distance from the test capsule 2. For this reason, by deriving and storing the threshold intensity according to the distance between the position where the magnetic field detection device 6 is arranged in advance and the test capsule 2 at the time of ejection from the subject 1, the magnetic field It is determined whether or not the test capsule 2 is located inside the subject 1 by determining whether or not the intensity of the electrical signal corresponding to the detected magnetic field obtained by the detection device 6 is equal to or greater than the threshold intensity. It can be derived.

  Advantages of the in-subject position detection system according to the second embodiment will be described. The in-subject position detection system according to the second embodiment can accurately determine the position of whether or not the test capsule 2 is located in the subject 1 with a simple configuration. In other words, the in-subject position detection system according to the second embodiment calculates the intensity of the electric signal and the threshold intensity extracted from the detected magnetic field in the magnetic field detection device 6 without performing specific distance derivation and position derivation. Position derivation is performed only by a simple configuration of comparison. In the second embodiment, as in the first embodiment, the magnetic field detection device 6 detects only the magnetic field component in the vertical direction in order to detect the magnetic field formed by the rotating magnetic field forming unit 17, and further detects the magnetic field component. Since only the component corresponding to the rotation frequency of the magnetic field forming unit 17 is extracted from the electrical signal corresponding to the magnetic field component, the position derivation is performed based on the accurate value from which the noise component is removed. . From the above, the in-subject position detection system according to the second embodiment can accurately determine whether or not the test capsule 2 is located inside the subject 1 with a simple configuration. Yes.

  In the second embodiment, a plurality of magnetic field detection devices 6 may be arranged in the same manner as in the first embodiment, but the position of the test capsule 2 can be derived even when a single magnetic field detection device 6 is used. Can be done. Therefore, the in-subject position detection system according to the second embodiment has an advantage in that the system can be constructed using the single magnetic field detection device 6.

(Embodiment 3)
Next, the in-subject position detection system according to the third embodiment will be described. The in-subject position detection system according to the third embodiment includes a capsule endoscope that includes not only a magnetic field forming unit but also a predetermined in-subject information acquisition unit and a radio unit as an in-subject introduction device, and magnetic field formation. A position information deriving device that switches a plurality of antennas that receive radio signals transmitted from the capsule endoscope based on the detection result of the position of the capsule endoscope in the subject based on the magnetic field generated by the means It has the composition provided.

  FIG. 8 is a schematic diagram illustrating an overall configuration of the in-subject position detection system according to the third embodiment. As shown in FIG. 8, the in-subject position detection system according to the third embodiment includes a capsule endoscope 50 that is an example of an in-subject introduction apparatus, and a position detection device 51. Although components corresponding to the display device 4 and the portable recording medium 5 in the first embodiment are not shown in FIG. 8, this is not intended to exclude them in the third embodiment. In addition, in the in-subject position detection system according to the third exemplary embodiment, components having the same reference numerals and names as those in the first and second exemplary embodiments are the same as those in the first exemplary embodiment unless otherwise specified below. It shall have the configuration and action of

  As shown in FIG. 8, the position detection device 51 includes magnetic field strength detection devices 6a to 6h, fixing members 7a and 7b for fixing the magnetic field strength detection devices 6a to 6h to the subject 1, and a capsule endoscope. 50, the reception antennas A1 to An for receiving radio signals transmitted from 50, the magnetic field intensity detection devices 6a to 6h and the information obtained by the reception antennas A1 to An are processed, and the capsule endoscope 50 A position information deriving device 52 that acquires position information in the subject 1. Although not shown in FIG. 8, the position detection device 51 has a function of supplying a power supply signal to the capsule endoscope 50 as will be described later. It has power feeding antennas B1 to Bm.

  The receiving antennas A1 to An are for receiving radio signals transmitted from the capsule endoscope 50. As will be described later, the capsule endoscope 50 according to the third embodiment has a function of capturing an image inside the subject 1 and wirelessly transmitting the image to the outside, and the receiving antennas A1 to An include the capsule endoscope. The wireless signal transmitted from the mirror 50 is received and output to the position information deriving device 52. Specifically, the receiving antennas A <b> 1 to An are configured by, for example, a loop antenna and a fixing unit for fixing the loop antenna to the subject 1. In addition, when a radio signal is transmitted from the capsule endoscope 50, the reception may be performed by all of the reception antennas A1 to An. However, in the third embodiment, reception is performed using a reception antenna that is determined to be most suitable for reception by an antenna selection unit 67 described later, among a plurality of reception antennas A1 to An.

  FIG. 9 is a block diagram showing a configuration of the capsule endoscope 50. As shown in FIG. As with the test capsule 2 in the first embodiment, the capsule endoscope 50 includes a magnetic field forming unit 17 as a magnetic field forming unit. Although only the magnetic field forming unit 17 is shown in FIG. 9, the actual configuration is similar to the configuration of the first embodiment shown in FIG. A mechanism is provided, and a mechanism in which the magnetic field output direction of the magnetic field forming unit 17 is always substantially coincident with the vertical direction is provided. Furthermore, the capsule endoscope 50 includes an LED 53 that functions as an illuminating unit for irradiating the imaging region when imaging the inside of the subject 1, an LED driving circuit 54 that controls the driving state of the LED 53, and the LED 53. A CCD 55 that functions as an image pickup unit that picks up a reflected light image from the irradiated region, and a CCD drive circuit 56 that controls the drive state of the CCD 55 are provided. The LED 53, the LED drive circuit 54, the CCD 55, and the CCD drive circuit 56 are defined as an in-subject information acquisition unit 57 that performs a predetermined function as a whole.

  The capsule endoscope 50 includes a transmission unit 58 that modulates image data picked up by the CCD 55 to generate a wireless signal, and a transmission antenna unit as a wireless unit that transmits the wireless signal output from the transmission unit 58. 59, and a system control circuit 60 for controlling the operation of the LED drive circuit 54, the CCD drive circuit 56 and the transmission unit 58.

  By providing these mechanisms, the capsule endoscope 50 acquires the image data of the region to be examined illuminated by the LED 53 while being introduced into the subject 1 by the CCD 55. The acquired image data is converted into a radio signal by the transmission unit 58 and then transmitted to the outside via the transmission antenna unit 59.

  The capsule endoscope 50 includes a reception antenna unit 61 that receives a radio signal transmitted from the position detection device 51 side, and a separation circuit 62 that separates a power feeding signal from a signal received by the reception antenna unit 61. Is provided. Further, the capsule endoscope 50 includes a power regeneration circuit 63 that regenerates power from the separated power supply signal, a booster circuit 64 that boosts the regenerated power, and a capacitor 65 that stores the boosted power. Prepare. Further, the capsule endoscope 50 detects the content of the control information signal from the component separated from the power feeding signal by the separation circuit 62 and outputs the detected control information signal to the system control circuit 60. A circuit 66 is provided. The system control circuit 60 also has a function of distributing the driving power supplied from the battery 65 to other components.

  By providing these mechanisms, the capsule endoscope 50 first receives the radio signal transmitted from the position detection device 51 side at the reception antenna unit 61 and feeds power from the received radio signal by the separation circuit 62. Separate the control signal and control information signal. The control information signal separated by the separation circuit 62 is output to the system control circuit 60 through the control information detection circuit 66 and used for driving control of the LED 53, the CCD 55 and the transmission unit 58. On the other hand, the power supply signal is regenerated as power by the power regeneration circuit 63, and the regenerated power is boosted to a potential suitable for the capacitor 65 by the booster circuit 64 and then stored in the capacitor 65.

  Next, the configuration of the position information deriving device 52 will be described. FIG. 10 is a block diagram illustrating a configuration of the position information deriving device 52. The position information deriving device 52 according to the third embodiment includes a band filter unit 39, an A / D conversion unit 40, and a lock-in amplifier unit 41 as components for detecting the position of the capsule endoscope 50 in the subject 1. , A distance deriving unit 42, a correspondence relationship database 43, and a position deriving unit 44. Note that the operation of detecting the position of the capsule endoscope 50 in the third embodiment is substantially the same as that in the first embodiment, and a detailed description thereof will be omitted.

  The position information deriving device 52 also has a function as a receiving device that receives image data inside the subject 1 that is wirelessly transmitted from the capsule endoscope 50. Specifically, the position information deriving device 52 demodulates the radio signal received by the antenna selection unit 67 that selects one to be used for data reception from the reception antennas A1 to An and the selected reception antenna. The receiving unit 68 that extracts and outputs image data acquired by the capsule endoscope 50 from the wireless signal, and an image processing unit that performs necessary processing on the output image data 69 and a storage unit 70 for recording image data that has undergone image processing.

  The antenna selection unit 67 is for selecting the most suitable receiving antenna for receiving a radio signal transmitted from the capsule endoscope 50. Specifically, the antenna selection unit 67 grasps the positions of the receiving antennas A1 to An in advance, and receives information related to the position of the capsule endoscope 50 derived by the position deriving unit 44. Have For this reason, the antenna selection unit 67 selects a reception antenna that is estimated to have the best reception sensitivity in relation to the position of the capsule endoscope 50, and is received by the selected reception antenna. A function of outputting a radio signal to the receiving unit 68 is provided.

  The storage unit 70 has a function of storing the image data output from the image processing unit 69 in association with the position of the capsule endoscope 50 at the time when the output image data is captured. That is, the position information deriving device 52 has a configuration in which the information obtained in the position deriving unit 44 and the image processing unit 69 is output to the storage unit 70 as shown in FIG. It has a function of storing these pieces of information in an associated state. As a result, the storage unit 70 stores the image data of a predetermined area inside the subject 1 and the position of the capsule endoscope 50 at the time of capturing the image data.

  Further, the position information deriving device 52 has a function of generating a power feeding signal and the like to be transmitted to the capsule endoscope 50 and outputting the power feeding antennas B1 to Bm. Specifically, the position information deriving device 52 receives an oscillator 71 having a function of generating a power feeding signal and a function of defining an oscillation frequency, and a control information signal for controlling the driving state of the capsule endoscope 50. A control information input unit 72 to be generated, a superimposing circuit 73 for combining the power feeding signal and the control information signal, and an amplifier circuit 74 for amplifying the intensity of the combined signal are provided. The signal amplified by the amplifier circuit 74 is sent to the power feeding antennas B <b> 1 to Bm and sent to the capsule endoscope 50. The position information deriving device 52 includes a power supply unit 75 including a predetermined power storage device or an AC power adapter, and each component of the position information deriving device 52 drives electric power supplied from the power supply unit 75. Energy is used.

  Next, advantages of the in-subject position detection system according to the third embodiment will be described. First, in the in-subject position detection system according to the third embodiment, the magnetic field forming unit 17 is provided in the capsule endoscope 50 as in the first embodiment, and based on the magnetic field formed by the magnetic field forming unit 17. Thus, the position of the capsule endoscope 50 is detected. As described above, the magnetic field has a characteristic of decaying with distance, so that the position of the capsule endoscope 50 can be detected more accurately than when position detection is performed using a wireless signal. Have advantages.

  The in-subject position detection system according to the third embodiment has a configuration in which the antenna selection unit 67 selects a reception antenna based on the derived position of the capsule endoscope 50. The reception sensitivity of the radio signal in the reception antenna depends on the distance from the capsule endoscope 50 and the directivity of the transmission antenna unit 59 provided in the capsule endoscope 50. Accordingly, it is possible to accurately select a reception antenna to be used based on the position of the capsule endoscope 50, and position information that can always receive a radio signal transmitted from the capsule endoscope 50 with high sensitivity. A detection system can be realized.

  Furthermore, the in-subject position detection system according to the third embodiment has a configuration in which the imaged image data in the subject 1 and the derived position of the capsule endoscope 50 are output to the storage unit 70. . Therefore, the image data acquired by the capsule endoscope 50 and the derived position of the capsule endoscope 50 at the time of imaging can be stored in association with each other, and the display device 4 can store the image data. When displaying, it is possible to specify to display only image data located in a predetermined range. That is, instead of displaying all image data on the display device 4, it is possible to display only the region of interest to the user, for example, image data of only the small intestine, and a position information detection system that is convenient for doctors and the like. It is possible to realize.

  As described above, the present invention has been described over the first to third embodiments. However, the present invention is not limited to the above-described ones, and those skilled in the art can conceive various examples, modified examples, and application examples. Is possible. For example, the in-subject position detection system according to the third embodiment is configured by diverting the configuration shown in the first embodiment with respect to the position detection mechanism. It is good also as a structure which diverted the position detection mechanism shown. In such a case, for example, after it is determined that the capsule endoscope 50 has been ejected outside the subject 1 by the position detection mechanism, the position information deriving device is stopped driving. It's also good.

  In addition, the configuration of the magnetic field forming unit 17 shown in FIG. 2 is formed by the rod-shaped permanent magnets 17a and 17b, but it is not necessary to interpret the configuration limited to such a configuration. What is important in the first to third embodiments is that the magnetic field forming unit 17 forms a magnetic field component having a predetermined intensity in the vertical direction at least every predetermined period, and more preferably, the magnetic field component in the vertical direction The intensity varies according to a predetermined period. Therefore, any configuration other than the configuration shown in FIG. 2 can be used in the present invention as long as such a function can be realized.

1 is a schematic diagram illustrating an overall configuration of an in-subject position detection system according to a first exemplary embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a test capsule forming the in-subject position detection system according to the first exemplary embodiment. 1 is a schematic diagram illustrating a configuration of a magnetic field detection device that forms an in-subject position detection system according to a first exemplary embodiment; 1 is a block diagram illustrating a configuration of a position information deriving device that forms an in-subject position detection system according to a first embodiment; 4 is a flowchart for explaining the contents of test capsule position derivation by the in-subject position detection system according to the first embodiment; FIG. 6 is a block diagram illustrating a configuration of a position information deriving device that forms an in-subject position detection system according to a second exemplary embodiment; 10 is a flowchart for explaining the content of test capsule position derivation by the in-subject position detection system according to the second embodiment; FIG. 6 is a schematic diagram illustrating an overall configuration of an in-subject position detection system according to a third exemplary embodiment. FIG. 6 is a block diagram illustrating a configuration of a capsule endoscope that forms an in-subject position detection system according to a third embodiment; FIG. 10 is a block diagram illustrating a configuration of a position information deriving device that forms an in-subject position detection system according to a third embodiment;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subject 2 Test capsule 3 Position detection apparatus 4 Display apparatus 5 Portable recording medium 6a-6h Magnetic field intensity detection apparatus 7a, 7b Fixing member 8 Position information derivation apparatus 11 Case 12 Case member 13 Filling member 14 Liquid 15 Spherical shell member DESCRIPTION OF SYMBOLS 16 Drive mechanism 17 Magnetic field formation part 17a, 17b Permanent magnet 18 Shaft member 21 Case member 22 Spherical body 23 Liquid 24 Magnetic field sensor part 25 Magnetic field measurement system control part 26 Electric power storage device 27 Power reception unit 28 Transmission / reception unit 29 Transmission / reception antenna 30 Power reception antenna 31 Weight member 32 Feeding antenna 33 Transmission / reception antenna 34 Feeding unit 35 Transmission / reception unit 36 Control unit 38 Position calculation unit 39 Band filter unit 40 A / D conversion unit 41 Lock-in amplifier unit 42 Distance deriving unit 43 Correspondence relationship database 44 Position deriving unit 45 Storage unit 46 Location information deriving device 47 position deriving section 50 capsule endoscope 51 position detecting device 52 the position processor 53 LED
54 LED drive circuit 55 CCD
56 CCD drive circuit 57 In-subject information acquisition unit 58 Transmission unit 59 Transmission antenna unit 60 System control circuit 61 Reception antenna unit 62 Separation circuit 63 Power regeneration circuit 64 Booster circuit 65 Capacitor 66 Control information detection circuit 67 Antenna selection unit 68 Reception unit 69 Image processing unit 70 Storage unit 71 Oscillator 72 Control information input unit 73 Superimposition circuit 74 Amplification circuit 75 Power supply unit

Claims (13)

A position detection device that detects the position of an in-subject introduction device that is introduced into a subject and at least periodically forms a vertical magnetic field component,
Magnetic field detection means for detecting the magnetic field strength in the vertical direction;
Storage means for storing the correspondence between the magnetic field strength and the distance from the in-subject introduction device;
A distance deriving unit for deriving a distance between the magnetic field detecting unit and the in-subject introducing device based on the magnetic field intensity detected by the magnetic field detecting unit and the correspondence relationship stored in the storage unit;
Position deriving means for deriving the position of the in-subject introduction device based on the result derived by the distance deriving means;
A position detection device comprising: A plurality of the magnetic field detection means are arranged at predetermined positions on the subject,
2. The position according to claim 1, wherein the position deriving unit derives the position of the in-subject introduction device based on a distance between the plurality of magnetic field detection units and the in-subject introduction device. Detection device. A position detection device that detects the position of an in-subject introduction device that is introduced into a subject and at least periodically forms a vertical magnetic field component,
Magnetic field detection means for detecting the magnetic field strength in the vertical direction;
Position deriving means for deriving whether or not the in-subject introduction apparatus is located outside the subject based on the intensity of the magnetic field detected by the magnetic field detection means;
A position detection device comprising:   The position deriving unit determines that the in-subject introduction device is located outside the subject when the intensity of the magnetic field detected by the magnetic field detecting unit is less than a predetermined threshold. 4. The position detection device according to 3. The in-subject introduction device forms a magnetic field in which the intensity in the vertical direction changes periodically,
The apparatus further comprises: a component extracting unit that extracts a frequency component corresponding to a period of a magnetic field formed by the in-subject introducing device from the vertical magnetic field components detected by the magnetic field detecting unit. Item 5. The position detection device according to any one of Items 1 to 4.   6. The position detection apparatus according to claim 5, wherein the component extraction means includes band filter means for passing a frequency component corresponding to a period of a magnetic field formed by the in-subject introduction apparatus.   The position detection apparatus according to claim 5, wherein the component extraction unit includes a lock-in amplifier that detects a frequency component corresponding to a period of a magnetic field formed by the in-subject introduction apparatus. An in-subject introduction device that is introduced into the subject and moves within the subject, and a position detection device that is disposed outside the subject and acquires position information of the in-subject introduction device within the subject; An in-subject position detection system comprising:
The in-subject introduction apparatus includes a magnetic field forming unit that forms a vertical magnetic field component at least periodically,
The position detection device includes:
Magnetic field detection means for detecting a vertical magnetic field component;
Storage means for storing the correspondence between the magnetic field strength and the distance from the in-subject introduction device;
A distance deriving unit for deriving a distance between the magnetic field detecting unit and the in-subject introduction device based on the magnetic field intensity detected by the magnetic field detecting unit and the correspondence relationship stored in the storage unit;
Position deriving means for deriving the position of the in-subject introduction device based on the result derived by the distance deriving means;
An in-subject position detection system comprising: An in-subject introduction device that is introduced into the subject and moves within the subject, and a position detection device that is disposed outside the subject and acquires position information of the in-subject introduction device within the subject; An in-subject position detection system comprising:
The in-subject introduction apparatus includes a magnetic field forming unit that forms a vertical magnetic field component at least periodically,
The position detection device includes:
Magnetic field detection means for detecting a vertical magnetic field component;
Position deriving means for deriving whether or not the in-subject introduction apparatus is located outside the subject based on the intensity of the magnetic field detected by the magnetic field detection means;
An in-subject position detection system comprising: The in-subject introduction device comprises:
In-subject information acquisition means for acquiring the in-subject information;
Wireless transmission means for wirelessly transmitting the in-subject information acquired by the in-subject information acquisition means,
The position detection device includes:
The in-subject position detection system according to claim 8 or 9, further comprising receiving means for receiving a radio signal including the in-subject information transmitted from the wireless transmission means. A plurality of the receiving means are arranged,
The position detection device further includes selection means for selecting the reception means used for receiving a radio signal based on the position of the in-subject introduction apparatus derived by the position information deriving means. The in-subject position detection system according to claim 10. The in-subject information acquisition means includes
Illumination means for irradiating the inside of the subject;
Imaging means for acquiring an image in the subject irradiated by the illumination means;
The in-subject position detection system according to claim 10 or 11, further comprising:   The said position detection apparatus is further provided with the memory | storage means which matches and memorize | stores the image acquired by the said imaging means, and the position of the said in-subject introduction apparatus at the time of acquisition of this image. The in-subject position detection system described in 1.

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