JP4554301B2 - Position detection apparatus and in-subject introduction system - Google Patents

Description

  The present invention relates to a technique for performing position detection of a detection target using a position detection magnetic field having position dependency with respect to intensity at least at a first time and a second time after a predetermined time has elapsed from the first time.

  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, a doctor or a nurse can make a diagnosis by displaying an image of an organ on a display based on image data stored in a memory (for example, see Patent Document 1). .).

  Further, a conventional capsule endoscope system has been proposed that includes a mechanism for detecting the position of the capsule endoscope in the body cavity. For example, a magnetic field having a position dependency with respect to strength is formed inside a subject to which a capsule endoscope is introduced, and the inside of the subject is determined based on the strength of the magnetic field detected by a magnetic field sensor built in the capsule endoscope. It is possible to detect the position of the capsule endoscope. In such a capsule endoscope system, in order to form a magnetic field, a configuration in which a predetermined coil is arranged outside the subject is adopted, and a magnetic field is generated inside the subject by flowing a predetermined current through the coil. Trying to form. It should be noted that the magnetic field formed for position detection needs to be formed so that the capsule endoscope has a detectable intensity in all regions where the capsule endoscope can exist inside the subject. Specifically, in a conventional capsule endoscope system, a magnetic field that can be detected by the capsule endoscope is formed in all digestive organs from the oral cavity to the anus.

Japanese Patent Laid-Open No. 2003-19111

  However, the conventional capsule endoscope system provided with the position detection mechanism has a problem that power consumption is significantly increased. That is, in order to form a magnetic field having a position dependency with respect to intensity in the subject, a large current is supplied to the coil during the several hours to several tens of hours that the capsule endoscope stays in the subject. There is a need to continue. In particular, in the conventional capsule endoscope system, as described above, a magnetic field having a strength that can be detected by the capsule endoscope is formed on the entire digestive organ inside the subject. The required power becomes enormous and is not appropriate from the viewpoint of reducing power consumption.

  The present invention has been made in view of the above, and is necessary and sufficient for a position detection device that performs position detection of a detection target such as a capsule endoscope using a position detection magnetic field having position dependency. An object of the present invention is to realize a position detection device capable of forming a position detection magnetic field and an in-subject introduction system using the position detection device.

  In order to solve the above-described problems and achieve the object, the position detection device according to claim 1 has position dependency with respect to strength at least at a first time and a second time after a predetermined time has elapsed from the first time. A position detection device for detecting a position of a detection target using a position detection magnetic field, wherein the position detected at a position where the detection target exists, and magnetic field forming means for forming a position detection magnetic field of variable intensity Position deriving means for deriving the position of the detection target based on the intensity of the detection magnetic field, and the position detection magnetic field can be detected by the detection target at the second time based on the position of the detection target at the first time And a magnetic field intensity control means for controlling the magnetic field forming means so as to obtain a sufficient strength.

  According to the first aspect of the present invention, since the magnetic field strength control means for controlling the strength of the position detection magnetic field formed by the magnetic field forming means based on the detection symmetrical position at the first time is provided, for example, the first It is possible to prevent a useless position detection magnetic field from being formed in an area where it is predicted that a detection target is not clearly present at a second time after a predetermined time has elapsed from the time, which is necessary and sufficient for position detection. It is possible to form a strong position detecting magnetic field.

  According to a second aspect of the present invention, there is provided the position detecting device according to the first aspect, wherein the detection target can be present at the second time based on the position of the detection target at the first time. Range deriving means for deriving the position, and the magnetic field intensity control means controls the magnetic field forming means so as to form the position detecting magnetic field having a detectable intensity in the possible range derived by the range deriving means. It is characterized by that.

  According to a third aspect of the present invention, in the above invention, the position detection device further includes a movement speed deriving unit that derives the movement speed of the detection target in the predetermined time, and the range deriving unit includes the movement at the first time. A spherical region having a radius of a value obtained by multiplying the moving speed of the detection target by the predetermined time with the position of the detection target as a center is defined as a possible range at the second time.

  According to a fourth aspect of the present invention, in the above invention, the position detecting device according to the present invention includes a moving speed deriving unit for deriving a moving speed of the detection target in the predetermined time, and a movement for deriving a moving direction of the detection target in the predetermined time. A direction deriving unit, wherein the range deriving unit includes a position moved by a value obtained by multiplying the moving speed by the predetermined time with respect to the position of the detection target at the first time. An area is defined as the existence possible range.

  According to a fifth aspect of the present invention, in the above-described invention, the moving speed deriving unit is configured to determine the moving speed based on changes in the position of the detection target derived by the position deriving unit at a plurality of past times. Is derived.

  The position detection apparatus according to a sixth aspect of the present invention further includes a moving speed database in which the correspondence relationship between the position of the detection target and the position of the detection target in the subject is recorded, The moving speed deriving means derives the moving speed of the detection target at the predetermined time using the correspondence recorded in the moving speed database based on the position of the detection target at the first time. .

  According to a seventh aspect of the present invention, in the above invention, the moving direction deriving unit is configured to detect the detection target at the predetermined time based on a change in position detected by the position deriving unit at a plurality of past times. It is characterized by deriving the moving direction of.

  In the position detection device according to claim 8, in the above-described invention, the region where the detection target may exist is linear in a direction fixed with respect to a reference coordinate axis determined independently of the movement of the detection target. A traveling first linear magnetic field is formed, and the position detecting magnetic field is a second linear magnetic field that travels linearly in a direction different from the first linear magnetic field and fixed with respect to the reference coordinate axis. And the moving direction deriving means is based on the pointing direction of the detection target determined by the relationship between the target coordinate axis fixed with respect to the detection target and the traveling directions of the first linear magnetic field and the second linear magnetic field. The moving direction is derived.

  According to a ninth aspect of the present invention, in the above invention, the first linear magnetic field is formed by geomagnetism.

  According to a tenth aspect of the present invention, there is provided the position detection device according to the above invention, wherein the position deriving unit is configured to detect the intensity of the magnetic field formed in the vicinity of the magnetic field forming unit by the magnetic field forming unit and the position detected by the detection target. The distance between the magnetic field forming means and the detection target is derived based on the intensity of the magnetic field for detection, and the position of the detection target is derived using the derived distance.

  In addition, an in-subject introduction system according to an eleventh aspect includes an intra-subject introduction apparatus introduced into a subject, and positions relative to intensity at least at a first time and a second time after a predetermined time has elapsed from the first time. An intra-subject introduction system comprising a position detection device that detects the position of the intra-subject introduction device using a position detection magnetic field having dependency, wherein the intra-subject introduction device is formed by a magnetic field formed And a wireless transmission means for transmitting a wireless signal including information on the magnetic field intensity detected by the magnetic field sensor, and the position detecting device uses a position detecting magnetic field having a variable intensity. A magnetic field forming means to form, and a strength of the position detecting magnetic field detected by the magnetic field sensor extracted from the wireless signal received via a predetermined receiving antenna. And a position deriving means for deriving the position of the in-subject introduction apparatus based on the position, and the position detection magnetic field is detected by the magnetic field sensor at the second time based on the position of the in-subject introduction apparatus at the first time. Magnetic field intensity control means for controlling the magnetic field forming means so as to have a possible intensity is provided.

  The position detection apparatus and the in-subject introduction system according to the present invention include magnetic field strength control means for controlling the strength of the position detection magnetic field formed by the magnetic field forming means based on the position of detection symmetry at the first time. For example, it is possible to prevent a useless position detection magnetic field from being formed in an area where it is predicted that a detection target does not exist clearly at a second time after a predetermined time has elapsed since the first time. In this case, it is possible to form a position detection magnetic field having a necessary and sufficient strength.

  Hereinafter, a position detection apparatus and an in-subject introduction system, which are the best modes for carrying out the present invention (hereinafter simply referred to as “embodiments”), will be described. 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. In the following description, a technique using the first linear magnetic field, the second linear magnetic field, and the diffusion magnetic field is described as an example of the position detection mechanism. However, it should be understood that the present invention should not be limited to such a configuration. The present invention can be applied as long as the position of the detection target is detected over a plurality of times using a position detection magnetic field having position dependency.

(Embodiment 1)
First, the in-subject introduction system according to the first embodiment will be described. In the first embodiment, the overall configuration and each component of the in-subject introduction system will be described, the position detection mechanism will be described, and then the control mechanism related to the strength of the position detection magnetic field used for position detection will be described. I will do it.

  FIG. 1 is a schematic diagram illustrating the overall configuration of the intra-subject introduction system according to the first embodiment. As shown in FIG. 1, the in-subject introduction system according to the first embodiment includes a capsule endoscope 2 that is introduced into the subject 1 and moves along a passage route, and a capsule endoscope. A position detection device 3 that performs wireless communication with the camera 2 and detects a positional relationship between a target coordinate axis fixed to the capsule endoscope 2 and a reference coordinate axis fixed to the subject 1; In order to exchange information between the display device 4 that displays the contents of the radio signal transmitted from the capsule endoscope 2 and received by the position detection device 3, and between the position detection device 3 and the display device 4. The portable recording medium 5 is provided. As shown in FIG. 1, in the first embodiment, an object coordinate axis that is a coordinate axis that is formed by the X axis, the Y axis, and the Z axis and is fixed to the capsule endoscope 2, and the x axis, It is formed by the y-axis and the z-axis, is determined regardless of the movement of the capsule endoscope 2, and specifically sets a reference coordinate axis that is a coordinate axis fixed with respect to the subject 1, The positional relationship of the target coordinate axis with respect to the reference coordinate axis is detected using the mechanism described in (1).

  The display device 4 is for displaying an in-vivo image captured by the capsule endoscope 2 received by the position detection device 3 and is based on data obtained by the portable recording medium 5. It has a configuration such as a workstation that performs image display. Specifically, the display device 4 may be configured to directly display an image or the like by a CRT display, a liquid crystal display, or the like, or may be configured to output an image or the like to another medium such as a printer.

  The portable recording medium 5 can be attached to and detached from the processing device 12 and the display device 4 described later, and has a structure capable of outputting and recording information when attached to both. Specifically, the portable recording medium 5 is attached to the processing device 12 while the capsule endoscope 2 is moving in the body cavity of the subject 1, and the target coordinate axis with respect to the in-subject image and the reference coordinate axis. The positional relationship is stored. Then, after the capsule endoscope 2 is discharged from the subject 1, the capsule endoscope 2 is taken out from the processing device 12 and mounted on the display device 4, and the recorded data is read out by the display device 4. When data is transferred between the processing device 12 and the display device 4 using a portable recording medium 5 such as a compact flash (registered trademark) memory, the processing device 12 and the display device 4 are connected by wire. Unlike the capsule endoscope 2, the subject 1 can freely move even when the capsule endoscope 2 is moving inside the subject 1.

  Next, the capsule endoscope 2 will be described. The capsule endoscope 2 functions as an example of a detection target in the claims. Specifically, the capsule endoscope 2 is introduced into the subject 1, acquires in-subject information while moving in the subject 1, and transmits a radio signal including the acquired in-subject information to the outside It has the function to transmit to. In addition, the capsule endoscope 2 has a magnetic field detection function for detecting a positional relationship, which will be described later, and has a configuration in which driving power is supplied from the outside. Specifically, a radio signal transmitted from the outside is received. It has a function of receiving and reproducing the received radio signal as drive power.

  FIG. 2 is a block diagram showing a configuration of the capsule endoscope 2. As shown in FIG. 2, the capsule endoscope 2 functions as a mechanism for acquiring in-subject information. In-subject information acquisition unit 14 for acquiring in-subject information and the acquired in-subject information And a signal processing unit 15 for performing predetermined processing. The capsule endoscope 2 detects a magnetic field as a magnetic field detection mechanism, outputs a magnetic signal corresponding to the detected magnetic field, an amplifying unit 17 for amplifying the output electric signal, and an amplification And an A / D converter 18 that converts the electrical signal output from the unit 17 into a digital signal.

  The in-subject information acquisition unit 14 is for acquiring in-subject information, that is, an in-subject image as image data in the subject in the first embodiment. Specifically, the in-subject information acquisition unit 14 is an LED 22 that functions as an illumination unit, an LED drive circuit 23 that controls driving of the LED 22, and an imaging unit that captures at least a part of a region illuminated by the LED 22. A functioning CCD 24 and a CCD driving circuit 25 for controlling the driving state of the CCD 24 are provided. In addition, as a specific structure of an illumination part and an imaging part, it is not essential to use LED and CCD, For example, it is good also as using CMOS etc. as an imaging part.

  The magnetic field sensor 16 is for detecting the direction and intensity of the magnetic field formed in the region where the capsule endoscope 2 is present. Specifically, the magnetic field sensor 16 is formed using, for example, an MI (Magneto Impedance) sensor. The MI sensor has a configuration in which, for example, an FeCoSiB amorphous wire is used as a magnetosensitive medium. When a high frequency current is applied to the magnetosensitive medium, the MI impedance of the magnetosensitive medium greatly changes due to an external magnetic field. The magnetic field strength is detected using the effect. In addition to the MI sensor, the magnetic field sensor 16 may be configured using, for example, an MRE (magnetoresistive effect) element, a GMR (giant magnetoresistive effect) magnetic sensor, or the like.

  As shown in FIG. 1, in the first embodiment, a target coordinate axis defined by the X axis, the Y axis, and the Z axis is assumed as the coordinate axis of the capsule endoscope 2 to be detected. Corresponding to the target coordinate axis, the magnetic field sensor 16 detects the magnetic field strengths of the X direction component, the Y direction component, and the Z direction component for the magnetic field formed in the region where the capsule endoscope 2 is located, It has a function of outputting an electrical signal corresponding to the magnetic field strength in the direction. The magnetic field strength component on the target coordinate axis detected by the magnetic field sensor 16 is transmitted to the position detection device 3 via the wireless transmission unit 19 described later, and the position detection device 3 detects the value of the magnetic field component detected by the magnetic field sensor 16. Based on this, the positional relationship between the target coordinate axis and the reference coordinate axis is derived.

  Further, the capsule endoscope 2 includes a transmission circuit 26 and a transmission antenna 27, and performs signal processing on a wireless transmission unit 19 for performing wireless transmission to the outside and a signal output to the wireless transmission unit 19. And a switching unit 20 that appropriately switches between the output from the unit 15 and the output from the A / D conversion unit 18. Further, the capsule endoscope 2 includes a timing generation unit 21 for synchronizing the drive timings of the in-subject information acquisition unit 14, the signal processing unit 15, and the switching unit 20.

  The capsule endoscope 2 has a receiving antenna 28 and a power regeneration circuit that regenerates power from the radio signal received via the receiving antenna 28 as a mechanism for receiving a wireless signal for power feeding from the outside. 29, a booster circuit 30 that boosts the voltage of the power signal output from the power regeneration circuit 29, and a power signal that has been changed to a predetermined voltage by the booster circuit 30 is stored and supplied as drive power for the other components described above. The storage battery 31 is provided.

  The reception antenna 28 is formed using, for example, a loop antenna. Such a loop antenna is fixed at a predetermined position in the capsule endoscope 2, and is specifically arranged to have a predetermined position and a directing direction on a target coordinate axis fixed to the capsule endoscope 2. ing.

  Next, the position detection device 3 will be described. As shown in FIG. 1, the position detection device 3 includes receiving antennas 7 a to 7 d for receiving a radio signal transmitted from the capsule endoscope 2, and a radio for supplying power to the capsule endoscope 2. Transmission antennas 8a to 8d for transmitting signals, a first linear magnetic field forming unit 9 for forming a first linear magnetic field, a second linear magnetic field forming unit 10 for forming a second linear magnetic field, and a diffusion magnetic field are formed. A diffusion magnetic field forming unit 11 and a processing device 12 that performs predetermined processing on radio signals and the like received via the receiving antennas 7a to 7d are provided.

  The receiving antennas 7a to 7d are for receiving radio signals transmitted from the radio transmitting unit 19 provided in the capsule endoscope 2. Specifically, the receiving antennas 7a to 7d are formed by a loop antenna or the like, and have a function of transmitting a received radio signal to the processing device 12.

  The transmission antennas 8 a to 8 d are for transmitting the radio signal generated by the processing device 12 to the capsule endoscope 2. Specifically, the transmission antennas 8 a to 8 d are formed by a loop antenna or the like that is electrically connected to the processing device 12.

  It should be noted that the specific configurations of the receiving antennas 7a to 7d, the transmitting antennas 8a to 8d, the first linear magnetic field forming unit 9 described below, and the like are not limited to those shown in FIG. In other words, FIG. 1 schematically shows only these components, and the number of receiving antennas 7a to 7d and the like is not limited to the number shown in FIG. As for the shape and the like, any configuration can be adopted without being limited to that shown in FIG.

  The first linear magnetic field forming unit 9 is for forming a linear magnetic field in a predetermined direction in the subject 1. Here, the “linear magnetic field” refers to a magnetic field component substantially only in one direction in at least a predetermined spatial region, in this first embodiment, in a spatial region where the capsule endoscope 2 inside the subject 1 can be located. The magnetic field. Specifically, as shown in FIG. 1, the first linear magnetic field forming unit 9 also includes a coil formed so as to cover the body portion of the subject 1 and a current that supplies a predetermined current to the coil. A source (not shown) and having a function of forming a linear magnetic field in a spatial region inside the subject 1 by flowing a predetermined current through the coil. Here, an arbitrary direction may be selected as the traveling direction of the first linear magnetic field, but in the first embodiment, the first linear magnetic field is z on the reference coordinate axis fixed with respect to the subject 1. It is assumed that the magnetic field is a linear magnetic field traveling in the axial direction.

  FIG. 3 is a schematic diagram showing the first linear magnetic field formed by the first linear magnetic field forming unit 9. As shown in FIG. 3, the coil forming the first linear magnetic field forming unit 9 is formed so as to include the body of the subject 1 inside and has a configuration extending in the z-axis direction on the reference coordinate axis. Therefore, as shown in FIG. 3, the first linear magnetic field formed in the subject 1 by the first linear magnetic field forming unit 9 forms magnetic force lines that travel in the z-axis direction of the reference coordinate axis.

  Next, the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 will be described. Each of the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 functions as an example of a magnetic field forming unit in the claims, and the formed second linear magnetic field and the diffusion magnetic field are in the claims. It functions as an example of a position detection magnetic field. In the following description, the second linear magnetic field forming unit 10 will be described as an example of the magnetic field forming unit particularly with respect to a specific example, but as is clear from the description, the diffusion magnetic field forming unit 11 is used as an example of the magnetic field forming unit. Of course, the same holds true even when used.

  The second linear magnetic field forming unit 10 is for forming a second linear magnetic field that is a linear magnetic field that travels in a direction different from the first linear magnetic field. Further, the diffusion magnetic field forming unit 11 is different from the first linear magnetic field forming unit 9 and the second linear magnetic field forming unit 10 in that the magnetic field direction has a position dependency, which is the diffusion magnetic field forming unit 11 in the first embodiment. It is for forming the magnetic field which spreads as it separates from.

  FIG. 4 is a schematic diagram illustrating the configuration of the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 and the mode of the second linear magnetic field formed by the second linear magnetic field forming unit 10. As shown in FIG. 4, the second linear magnetic field forming unit 10 extends in the y-axis direction with respect to the reference coordinate axis, and supplies a current to the coil 32 and the coil 32 formed so that the coil cross section is parallel to the xz plane. And a current source 33. For this reason, as shown in FIG. 4, the second linear magnetic field formed by the coil 32 becomes a linear magnetic field at least inside the subject 1 and gradually decreases in strength as the distance from the coil 32 increases. Will have a position dependency.

  The diffusion magnetic field forming unit 11 includes a coil 34 and a current source 35 for supplying current to the coil 34. Here, the coil 32 is arranged to form a magnetic field having a traveling direction in a predetermined direction. In the case of the first embodiment, the traveling direction of the linear magnetic field formed by the coil 32 is the reference coordinate axis. In the y-axis direction. Further, the coil 34 is fixed at a position where a diffusion magnetic field that is the same as the magnetic field direction stored in the magnetic force line direction database 42 described later is formed.

  In the first embodiment, the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 have a function of adjusting the strength of the magnetic field to be formed according to the control by the magnetic field strength control unit 50 described later. Specifically, the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 adjust the current value supplied by the current sources 33 and 35 with respect to the control of the magnetic field strength control unit 50 to thereby adjust the magnetic field strength. It has a function to adjust.

  FIG. 5 is a schematic diagram showing an aspect of the diffusion magnetic field formed by the diffusion magnetic field forming unit 11. As shown in FIG. 5, the coil 34 provided in the diffusion magnetic field forming unit 11 is formed in a spiral shape on the surface of the subject 1, and the diffusion magnetic field formed by the diffusion magnetic field forming unit 11 is shown in FIG. Thus, in the magnetic field formed by the coil 34 (not shown in FIG. 5), the magnetic lines of force are once diffused radially and are incident on the coil 34 again.

  In the first embodiment, the first linear magnetic field forming unit 9, the second linear magnetic field forming unit 10, and the diffusion magnetic field forming unit 11 form magnetic fields at different times. That is, in the first embodiment, the first linear magnetic field forming unit 9 and the like are configured not to form a magnetic field at the same time but to form a magnetic field according to a predetermined order, and the magnetic field sensor 16 provided in the capsule endoscope 2 is configured. Are to detect the first linear magnetic field, the second linear magnetic field, and the diffusion magnetic field independently.

  Next, the configuration of the processing device 12 will be described. FIG. 6 is a block diagram schematically showing a specific configuration of the processing device 12. First, the processing device 12 has a function of performing reception processing of a radio signal transmitted by the capsule endoscope 2, and a reception antenna selection that selects any one of the reception antennas 7a to 7d corresponding to the function. Unit 37, a receiving circuit 38 for extracting the original signal included in the radio signal by performing demodulation processing or the like on the radio signal received via the selected receiving antenna, and processing the extracted original signal And a signal processing unit 39 for reconstructing an image signal and the like.

Specifically, the signal processing unit 39 has a function of reconstructing the magnetic field signals S1 to S3 and the image signal S4 based on the extracted original signal, and outputting them to appropriate components. Here, the magnetic field signals S1 to S3 are magnetic field signals corresponding to the first linear magnetic field, the second linear magnetic field, and the diffusion magnetic field detected by the magnetic field sensor 16, respectively. The image signal S4 corresponds to the in-subject image acquired by the in-subject information acquisition unit 14. The specific form of the magnetic field signals S _{1 to} S ₃ is expressed by a direction vector corresponding to the detected magnetic field intensity on the target coordinate axis fixed with respect to the capsule endoscope 2, and the magnetic field traveling direction on the target coordinate axis. And information on magnetic field strength. Further, the image signal S4 is output to the recording unit 43. The recording unit 43 is for outputting input data to the portable recording medium 5, and records not only the image signal S <b> 4 but also the result of position detection, which will be described later, on the portable recording medium 5. It has a function.

The processing device 12 is fixed to the subject 1 and the function of detecting the position of the capsule endoscope 2 in the subject 1 based on the magnetic field intensity detected by the capsule endoscope 2. A function of detecting an orientation formed by the target coordinate axis fixed with respect to the capsule endoscope 2 with respect to the reference coordinate axis. Specifically, among the signals transmitted by the capsule endoscope 2 and output by the signal processing unit 39, the magnetic field signals S ₁ and S ₂ corresponding to the detected intensities of the first linear magnetic field and the second linear magnetic field are used. Based on the direction deriving unit 40 for deriving the direction formed by the target coordinate axis with respect to the reference coordinate axis, the magnetic field signal S ₃ and the magnetic field signal S ₂ corresponding to the detection intensity of the diffusion magnetic field, and the deriving result of the direction deriving unit 40 A position deriving unit 41 for deriving the position of the endoscope 2, and a magnetic force line direction database 42 that records the correspondence between the traveling direction and position of the magnetic force lines constituting the diffusion magnetic field when the position deriving unit 41 derives the position. Prepare. The azimuth derivation and position derivation by these components will be described in detail later.

  Further, the processing device 12 has a function of wirelessly transmitting drive power to the capsule endoscope 2, and includes an oscillator 44 that defines a frequency of a wireless signal to be transmitted, and an intensity of the wireless signal output from the oscillator 44. And a transmission antenna selection unit 47 that selects a transmission antenna to be used for transmitting a radio signal. Such a radio signal is received by the receiving antenna 28 provided in the capsule endoscope 2 and functions as driving power for the capsule endoscope 2.

  Further, the processing device 12 includes a selection control unit 48 that controls an antenna selection mode by the reception antenna selection unit 37 and the transmission antenna selection unit 47. The selection control unit 48 is based on the azimuth and position of the capsule endoscope 2 derived by the azimuth deriving unit 40 and the position deriving unit 41, respectively, and the transmission antenna 8 and reception most suitable for transmission / reception with respect to the capsule endoscope 2 A function of selecting the antenna 7 is provided.

  The processing device 12 has a function of controlling the strength of the magnetic field formed by the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11. Specifically, the processing device 12 includes a movement speed deriving unit 48 that derives the movement speed of the capsule endoscope 2 based on the history of the position of the capsule endoscope 2 recorded in the recording unit 43, and a derivation. A range deriving unit 49 for deriving a range in which the capsule endoscope 2 is located based on the moving speed and the past position of the capsule endoscope 2, a second linear magnetic field forming unit 10 based on the derived range, and And a magnetic field intensity control unit 50 that controls the formation magnetic field strength of the diffusion magnetic field forming unit 11. The functions of the movement speed deriving unit 48 and the magnetic field strength control unit 50 will be described in detail later. In addition, the processing device 12 includes a power supply unit 51 for supplying driving power to these components.

  Next, the operation of the intra-subject introduction system according to the first embodiment will be described. In the following, after explaining the position detection mechanism of the capsule endoscope 2 to be detected, the second linear magnetic field and diffusion magnetic field intensity control mechanism used for position derivation and the like will be explained, and finally the overall operation Will be described.

  First, the position detection mechanism of the capsule endoscope 2 will be described. In the intra-subject introduction system according to the first embodiment, a positional relationship is derived between a reference coordinate axis fixed with respect to the subject 1 and a target coordinate axis fixed with respect to the capsule endoscope 2. Specifically, after deriving the azimuth of the target coordinate axis with respect to the reference coordinate axis, using the derived azimuth, the position of the origin of the target coordinate axis on the reference coordinate axis, that is, within the capsule type inside the subject 1 The position of the endoscope 2 is derived. Therefore, in the following description, after describing the azimuth derivation mechanism, the position derivation mechanism using the derived azimuth will be described. is there.

  The direction deriving mechanism performed by the direction deriving unit 40 will be described. FIG. 7 is a schematic diagram showing the relationship between the reference coordinate axis and the target coordinate axis when the capsule endoscope 2 is moving in the subject 1. As already described, the capsule endoscope 2 travels along the passage path inside the subject 1 and rotates by a predetermined angle with the traveling direction as an axis. Therefore, the target coordinate axis fixed with respect to the capsule endoscope 2 causes a azimuth shift as shown in FIG. 7 with respect to the reference coordinate axis fixed with respect to the subject 1.

  On the other hand, the first linear magnetic field forming unit 9 and the second linear magnetic field forming unit 10 are each fixed to the subject 1. Therefore, the first and second linear magnetic fields formed by the first linear magnetic field forming unit 9 and the second linear magnetic field forming unit 10 are in a fixed direction with respect to the reference coordinate axis, specifically, the first linear magnetic field is the reference coordinate axis. In the z-axis direction, the second linear magnetic field travels in the y-axis direction.

  Orientation derivation in the first embodiment is performed using the first linear magnetic field and the second linear magnetic field. Specifically, first, the magnetic field sensor 16 provided in the capsule endoscope 2 detects the traveling directions of the first linear magnetic field and the second linear magnetic field supplied in time division. The magnetic field sensor 16 is configured to detect magnetic field components in the X-axis direction, the Y-axis direction, and the Z-axis direction in the target coordinate axis, and information regarding the traveling direction of the detected first and second linear magnetic fields in the target coordinate axis is as follows. And transmitted to the position detection device 3 via the wireless transmission unit 19.

The radio signal transmitted by the capsule endoscope 2 is processed as the magnetic field signals S ₁ and S ₂ through processing by the signal processing unit 39 and the like. For example, in the example of FIG. 7, the magnetic field signal S ₁ includes information regarding coordinates (X ₁ , Y ₁ , Z ₁ ) as the traveling direction of the first linear magnetic field, and the magnetic field signal S ₂ includes the second Information about coordinates (X ₂ , Y ₂ , Z ₂ ) is included as the traveling direction of the linear magnetic field. On the other hand, the direction deriving unit 40 receives the magnetic field signals S ₁ and S ₂ and derives the direction of the target coordinate axis with respect to the reference coordinate axis. Specifically, the azimuth deriving unit 40 has coordinates (X ₃ ) at which the inner product value for both (X ₁ , Y ₁ , Z ₁ ) and (X ₂ , Y ₂ , Z ₂ ) is 0 on the target coordinate axis. , Y ₃ , Z ₃ ) as corresponding to the direction of the z axis in the reference coordinate axis. Then, the azimuth deriving unit 40 performs a predetermined coordinate conversion process based on the above correspondence, derives the coordinates on the reference coordinate axes of the X axis, the Y axis, and the Z axis in the target coordinate axis, and uses these coordinates as azimuth information. Output. The above is the direction deriving mechanism by the direction deriving unit 40.

Next, the position deriving mechanism of the capsule endoscope 2 by the position deriving unit 41 will be described. The position deriving unit 41 has a configuration in which magnetic field signals S ₂ and S ₃ are input from the signal processing unit 39, azimuth information is input from the azimuth deriving unit 40, and information stored in the magnetic force line azimuth database 42 is input. . The position deriving unit 41 derives the position of the capsule endoscope 2 as follows based on the input information.

First, the position deriving unit 41 uses the magnetic field signal S _2, performs the derivation of the distance between the second linear magnetic field generator 10 and the capsule endoscope 2. The magnetic field signal S ₂ corresponds to the detection result of the second linear magnetic field in the region where the capsule endoscope 2 exists, and the second linear magnetic field is arranged outside the subject 1 by the second linear magnetic field forming unit 10. Corresponding to this, the strength is attenuated as the distance from the second linear magnetic field forming unit 10 increases. By utilizing such properties, the position deriving unit 41, the intensity of the second linear magnetic field in the second linear magnetic field generator 10 near (determined from the current value to be supplied to the second linear magnetic field generator 10), from the magnetic field signal S ₂ The strength of the second linear magnetic field in the obtained region of the capsule endoscope 2 is compared, and the distance r between the second linear magnetic field forming unit 10 and the capsule endoscope 2 is derived. As a result of deriving the distance r, as shown in FIG. 8, it is clear that the capsule endoscope 2 is positioned on the curved surface 52 that is a set of points separated from the second linear magnetic field forming unit 10 by the distance r. It becomes.

Then, the position deriving unit 41 derives the position on the curved surface 52 of the capsule endoscope 2 based on the magnetic field signal S ₃ , the direction information derived by the direction deriving unit 40 and the information stored in the magnetic force direction database 42. . Specifically, based on the magnetic field signal S ₃ and orientation information, to derive the traveling direction of the diffusion field at the location of the capsule endoscope 2. Since the magnetic field signal S ₃ is a signal corresponding to the result of detecting the diffusion magnetic field based on the target coordinate axis, the direction of the diffusion magnetic field based on the magnetic field signal S ₃ is coordinated from the target coordinate axis to the reference coordinate axis using the azimuth information. By performing the conversion process, the traveling direction of the diffusion magnetic field on the reference coordinate axis at the position where the capsule endoscope 2 exists is derived. Since the magnetic field direction database 42 records the correspondence between the traveling direction and position of the diffusion magnetic field on the reference coordinate axis, the position deriving unit 41 is stored in the magnetic field direction database 42 as shown in FIG. The position corresponding to the traveling direction of the diffusion magnetic field derived by referring to the information is derived, and the derived position is specified as the position of the capsule endoscope 2. The position derivation mechanism by the position derivation unit 41 has been described above.

  Next, intensity control of the second linear magnetic field and the diffusion magnetic field will be described. Such control of the magnetic field intensity is performed for the purpose of reducing the power consumption required for forming the second linear magnetic field or the like used as the position detection magnetic field. More specifically, the magnetic field strength control in the first embodiment predicts the position of the capsule endoscope 2 to some extent in the position detection to be performed in the future, and the capsule endoscope 2 of the capsule endoscope 2 within the predicted range. The strength of the formed magnetic field is reduced as long as it can be detected by the magnetic field sensor 16 provided.

  In the first embodiment, the magnetic field strength control is roughly performed according to the following process. That is, the moving speed deriving unit 48 derives the moving speed of the capsule endoscope 2, the range deriving unit 49 derives the possible area of the capsule endoscope 2, and the magnetic field control unit 50 determines the possible existence area. It is control with the 2nd linear magnetic field formation part 10 and the diffusion magnetic field formation part 11 based. Hereinafter, the derivation of the moving speed, the derivation of the possible area, and the control of the second linear magnetic field forming unit 10 and the like will be described.

In the following description and FIG. 10 and subsequent times, time t means the time at which position detection is performed, and among time t, times t ₋₁ , t ₀ and t ₁ are the times at which position detection has already been performed, That is, it is a past time, and the time t ₂ is a time corresponding to the position detection to be performed from now on, and the magnetic field strength control is performed regarding the position detection at the time t ₂ . That is, in the first embodiment, the “first time” in the claims corresponds to the time t ₁ , the “second time” corresponds to the time t ₂ , and the “plural times in the past” The description will be made assuming that these correspond to t ₋₁ , t ₀ , and t ₁ .

FIG. 10 is a schematic diagram for explaining the moving speed and the derivation mechanism of the possible existence area. First, the moving speed deriving unit 48, recorded in the recording unit 43, different times t _-1, t _0, based on the position at t _1, the time t _-1 ~t travel distance r _-1 and time t ₀ of ₀ The movement distance r ₀ at ˜t ₁ is derived, and the past average movement speed is derived using the movement distance. Specifically, for example, the average velocity v _-1 at time t _-1 ~t _0, by using the average velocity v ₀ at time t ₀ ~t _1, the average moving speed at the time t ₁ ~t ₂ The value v is

v = (v ₋₁ + v ₀ ) / 2 = (1/2) {r ₋₁ / (t ₀ −t ₋₁ )} + {r ₀ / (t ₁ −t ₀ )} (1)

And derived. In the first embodiment, the moving speed at times t _{1 to} t ₂ may be other than that shown in the expression (1) as long as it is derived based on positions detected at a plurality of past times. For example, as the simplest configuration, it is possible to derive the moving speed at times t _{1 to} t _{2 with} v = v ₀ .

Then, the range deriving unit 49 derives the possible region of the capsule endoscope 2 at time t ₂ based on the moving speed derived by the moving speed deriving unit 48. Range derivation unit 49, as shown in FIG. 10, around the position of the capsule endoscope 2 detected at time t _1, and the derived travel speed, elapsed time from time t ₁ to time t ₂ Delta] t ( = T ₂ −t ₁ ) is derived as a spherical region 53 having a radius as a value obtained by multiplying by t ₂ −t ₁ ). That is, in the first embodiment, the capsule endoscope 2 is inferred by what and scope derivation unit 49 that exists in the time t ₂ in globular region 53 shown in FIG. 11.

  After the possible region is derived, the magnetic field strength control unit 50 adjusts the strength of the magnetic field formed by the second linear magnetic field forming unit 10 and the diffusion magnetic field forming unit 11 so as to cover the region. FIG. 11 is a schematic diagram illustrating the control of the magnetic field strength related to the second linear magnetic field forming unit 10 as an example of the control by the magnetic field strength control unit 50. In FIG. 11, “magnetic field forming region” refers to a region where a significant magnetic field is formed with respect to position detection. Specifically, for example, the magnetic field sensor 16 provided in the capsule endoscope 2 can detect the magnetic field. An area where a strong magnetic field is formed. Under the control of the magnetic field strength control unit 50, the second magnetic field forming unit 10 forms a magnetic field so that power consumption is minimized under the condition that the magnetic field forming region 54 includes the spherical region 53. Specifically, the second linear magnetic field forming unit 10 has a characteristic in which the intensity decreases as the distance from the second linear magnetic field forming unit 10 increases, so that the second linear magnetic field forming unit 10 is located farthest in the spherical region 53. The magnetic field is formed so that the portion to be overlapped with the peripheral edge of the magnetic field forming region 54. The above is the magnetic field intensity control mechanism by the magnetic field intensity control unit 50.

  Using the position detection mechanism and the magnetic field intensity control mechanism described above, the processing device 12 operates according to the flowchart shown in FIG. First, the magnetic field intensity control unit 50 controls the second linear magnetic field forming unit 10 and the like so that the magnetic field forming region covers the entire subject 1 in order to perform initial position detection, and a magnetic field corresponding to the control is formed. (Step S101). Then, using the formed magnetic field, position derivation is performed by the above-described mechanism (step S102). Based on the detected position and the like, inside the capsule mold after a predetermined time (= Δt) has elapsed since the position detection in step S102. The possible range of the endoscope 2 is derived (step S103).

  Thereafter, the magnetic field strength control unit 50 sets a magnetic field formation region corresponding to the possible range, and controls the second linear magnetic field formation unit 10 and the like to realize the magnetic field formation region (step S104). The position of the capsule endoscope 2 after the elapse of a predetermined time is derived while feeding back the contents (step S105). Then, it is determined whether or not the position detection is finished (step S106). When the position detection is not finished (step S106, No), the process returns to step S103 again and the above-described processing is repeated. Note that the processing device 12 reconstructs and records in-vivo image data based on the radio signal transmitted from the capsule endoscope 2 and the driving power for the capsule endoscope 2 in accordance with the above operation. Although an operation such as transmission is performed, it is not a characteristic part of the present invention, and thus the description thereof is omitted here.

  Note that the reason why the magnetic field formation region is set so as to cover the entire subject in step S101 is that it is difficult to derive the possible range by the above-described mechanism in the first position detection. In other words, in the mechanism described above, the possible range can be derived using previously detected positions, etc., so that only the first position detection operation is performed according to the same mechanism as before. It becomes.

  In step S105, the position derivation by the position deriving unit 41 is performed while feeding back the control content by the magnetic field intensity control unit 50 based on the following reason. That is, in the derivation of the position r, particularly the derivation of the distance r between the second linear magnetic field forming unit 10 and the capsule endoscope 2 shown in FIG. 8, the second output from the second linear magnetic field forming unit 10 is performed. This utilizes the characteristic that the intensity of the linear magnetic field attenuates as the distance from the second linear magnetic field forming unit 10 increases. Specifically, since the position deriving unit 41 derives the distance r based on the strength attenuation rate of the second linear magnetic field, it is necessary to grasp the magnetic field strength in the vicinity of the second linear magnetic field forming unit 10. Therefore, at the time of position derivation in step S105, the position derivation unit 41 (and the azimuth derivation unit 40 if necessary) receives information related to the control content from the magnetic field strength control unit 50, and uses this information to determine the position. We are going to do detection.

  Next, advantages of the in-subject introduction system according to the first embodiment will be described. The in-subject introduction system according to the first embodiment performs position detection of the capsule endoscope using the formed magnetic field, and controls the position of the capsule endoscope by controlling the intensity of the magnetic field used for position detection to a necessary and sufficient value. There is an advantage that power consumption in the entire detection device 3 can be reduced.

In other words, in the intra-subject introduction system according to the first embodiment, as shown in FIG. 11, it exists as a region where the capsule endoscope 2 is likely to exist at the time of position detection (= t ₂ ). A possible range is set, and magnetic field formation is performed within a limit that covers such a possible range. Therefore, compared with the conventional case where the magnetic field is formed so as to cover the entire subject 1, the magnetic field formation region can be significantly narrowed, and the amount of power required for forming the magnetic field can be reduced. It is possible to realize an in-subject introduction system with low power consumption.

  Further, in the intra-subject introduction system according to the first embodiment, since the magnetic field forming region is set narrower than the conventional one, there is an advantage that the influence on the peripheral device can be reduced more than the conventional one. That is, by setting the magnetic field formation region narrow, the strength of the magnetic field formed outside the subject 1 is also reduced, and the influence on the electronic device or the like located outside the subject 1 can be reduced. Is possible.

Furthermore, as shown in FIG. 11, the in-subject introduction system according to the first embodiment has a derived moving speed v centered on the position of the capsule endoscope 2 at time t ₁ as a possible range. The spherical region 53 having a radius that is a value obtained by multiplying the elapsed time Δt is derived. By defining the existence range by the spherical region 53, it is possible to derive the existence range having high certainty.

In general, the capsule endoscope 2 has a characteristic that the moving speed changes according to the passage region inside the subject 1. Therefore, for example, when the possible range is determined uniformly with respect to the position at time t _1, in the region where the capsule endoscope 2 moves at high speed like the esophagus, the possible range at time t 2. There is a high probability that the capsule endoscope 2 will be located at a position away from the position, and reliable position detection cannot be performed. On the other hand, in the first embodiment, since the moving speed is derived based on the past detection result and the range that can be reached by the derived moving speed is set as the possible existence range, the existence possible range is adopted. Thus, there is no adverse effect as in the case of uniformly determining the existence range, and it is possible to derive a possible existence range having high certainty. That is, the in-subject introduction system according to the first embodiment has an advantage that the power required for magnetic field formation can be reduced while maintaining the position detection accuracy.

(Embodiment 2)
Next, the in-subject introduction system according to the second embodiment will be described. The in-subject introduction system according to the second embodiment relates to the position and moving speed of the capsule endoscope 2 in the subject 1 with respect to the moving speed of the capsule endoscope 2 performed as a premise of control of the magnetic field strength. The relationship is derived by using a database in which the relationship between and is previously recorded.

  FIG. 13 is a schematic block diagram showing a configuration of the processing device 55 provided in the in-subject introduction system according to the second embodiment. The in-subject introduction system according to the second embodiment basically has the same configuration as the in-subject introduction system according to the first embodiment, and although not shown, Similarly, a capsule endoscope 2, a display device 4, and a portable recording medium 5 are provided. As for the position detection device, in addition to the processing device 55 described below, the reception antennas 7a to 7d, the transmission antennas 8a to 8d, the first linear magnetic field forming unit 9, and the second linear magnetic field formation are performed as in the first embodiment. Part 10 and diffusion magnetic field forming part 11. Further, the processing device 55 having the same name and code as the processing device 12 in the first embodiment has the same structure and function as in the first embodiment unless otherwise specified.

  The processing apparatus 55 provided in the intra-subject introduction system according to the second embodiment is newly provided with a moving speed database 56 as shown in FIG. The moving speed database 56 has a function of recording information about the correspondence between the position of the capsule endoscope 2 in the subject 1 and the moving speed, and the moving speed deriving unit 57 is recorded in the recording unit 43. The function of deriving the moving speed of the capsule endoscope 2 at the second time based on the position of the capsule endoscope 2 at the first time and the information recorded in the moving speed database 56 is provided.

  The moving speed of the capsule endoscope 2 does not always maintain a constant value inside the subject 1, but usually varies due to the structure of the digestive organs that pass through, for example, passes through the esophagus. When moving through the small intestine, the movement speed is reduced. In Embodiment 2, the capsule endoscope 2 pays attention to the characteristic that the moving speed changes according to the position in the subject 1, and classifies the correspondence relationship between the position in the subject and the moving speed in advance. The movement speed is derived by preparing the categorized correspondence as data.

  FIG. 14 is a schematic diagram illustrating an example of the content of information recorded in the moving speed database 56. As shown in FIG. 14, the moving speed database 56 roughly divides the region through which the capsule endoscope 2 passes into three as an example. Specifically, the moving speed database 56 stores the positions of a first speed area 59 corresponding to the esophagus, a second speed area 60 corresponding to the stomach, and a third speed area 61 corresponding to the small and large intestines. Each has a function of storing the maximum speed.

In contrast, the movement speed deriving unit 57 derives the movement speed of the capsule endoscope 2 as follows. That is, the moving speed deriving unit 57 first refers to the recording unit 43 and acquires information regarding the position of the capsule endoscope 2 at the first time (time t ₁ ). Then, the moving speed deriving unit 57 determines in which speed region the capsule endoscope 2 is located at the first time based on the acquired position of the capsule endoscope 2 and relates to the corresponding moving speed. Get information. For example, in the example of FIG. 14, the moving speed deriving unit 57 determines that it belongs to the second speed area 60, and uses the speed stored in the moving speed database 56 as corresponding to the second speed area 60 as the second speed area 60. It has a function of grasping it as the moving speed of the capsule endoscope 2 at time (time t ₂ ) and outputting it to the range deriving unit 49.

  Advantages of the in-subject introduction system according to the second embodiment will be described. In the second embodiment, in addition to the advantages in the first embodiment, there is an advantage that the moving speed can be easily derived. That is, in the second embodiment, the moving speed deriving unit 57 inputs the corresponding information from the moving speed database 56 based on the position of the capsule endoscope 2 that has already been detected at the first time. Is derived. Therefore, the second embodiment has an advantage that it is not necessary to perform arithmetic processing or the like in deriving the moving speed, and the moving speed can be derived quickly and easily.

(Embodiment 3)
Next, the in-subject introduction system according to the third embodiment will be described. The in-subject introduction system according to the third embodiment derives a more certain existence range by deriving not only the movement speed but also the movement direction when deriving the existence range. It is possible.

  FIG. 15 is a schematic block diagram illustrating a configuration of the processing device 63 provided in the in-subject introduction system according to the third embodiment. As in the case of the second embodiment, although not shown, the intra-subject introduction system according to the third embodiment includes the capsule endoscope 2, the display device 4, and the portable recording medium 5. In addition to the processing device 63 described below, the position detection device also includes receiving antennas 7a to 7d as in the first embodiment. Further, components having the same names and symbols as those of the first and second embodiments have the same structure and function as those of the first and second embodiments unless otherwise specified below.

  As shown in FIG. 15, the processing device 63 has a configuration further including a movement direction deriving unit 64. The movement direction deriving unit 64 has a function of deriving the movement direction of the capsule endoscope 2 based on the directivity direction of the capsule endoscope 2 at the first time recorded in the recording unit 43, and the derived movement The direction has a function of outputting to the range deriving unit 65. In response to the newly provided moving direction deriving unit 64, the range deriving unit 65 uses the position of the capsule endoscope 2 recorded in the recording unit 43 and the moving speed deriving unit 48 at the first time. Based on the derived moving speed and the moving speed derived by the moving direction deriving unit 64, the capsule endoscope 2 has a function of deriving the possible range of the capsule endoscope 2 at the second time.

FIG. 16 is a schematic diagram for explaining the derivation mechanism of the possible existence range in the third embodiment. With respect to the position of the capsule endoscope 2 at time t ₁ (first time), the moving speed deriving unit 48 derives the moving speed v, and the moving direction deriving unit 64 moves the moving directions (a ₁ , b ₁ , c). ₁ ) is derived. On the other hand, the capsule endoscope 2 at time t ₂ (second time) is expected to move to a point moved by vΔt in the moving direction as shown in FIG. The unit 65 derives a predetermined area including such a point as the possible range 66. Then, the magnetic field intensity control unit 50 controls the second linear magnetic field forming unit 10 to form a magnetic field forming region 67 including the possible range 66, for example.

The advantages of the intra-subject introduction system according to the third embodiment will be described. In the third embodiment, as described above, a configuration using not only the moving speed but also the moving direction is adopted for deriving the possible range. Therefore, as in the first and second embodiments, the moving direction is not particularly taken into consideration, and the possible range is derived as a spherical region centered on the position of the capsule endoscope 2 at time t ₁ . It is possible to narrow the possible range of existence. Therefore, in the case of the example shown in FIG. 16, the magnetic field formation region is narrower than in the case where the spherical region centered on the position of the capsule endoscope 2 at time t ₁ is set as the possible range. The power consumption required for magnetic field formation in the second linear magnetic field forming unit 10 and the like can be further reduced.

(Modification)
Next, a modification of the in-subject introduction system according to the third embodiment will be described. In the third embodiment, the movement direction deriving unit 64 derives the movement direction based on the pointing direction of the capsule endoscope 2 recorded at the time t ₁ recorded in the recording unit 43. In this modification, The moving direction is derived based on the position of the capsule endoscope 2 at a plurality of past times.

FIG. 17 is a schematic diagram for explaining a moving direction derivation mechanism in the present modification. As shown in FIG. 17, in this modification, the moving direction vectors (a ₂ , b ₂ from time t ₋₁ to time t ₀ are based on the positions at a plurality of times t ₋₁ , t ₀ , t ₁ in the past. , C ₂ ) and movement direction vectors (a ₄ , b ₄ from time t ₁ to time t ₂ ) based on movement direction vectors (a ₃ , b ₃ , c ₃ ) from time t ₀ to time t _1. , C ₄ ). Specifically, for example, a moving direction vector from time t ₁ to time t ₂ is derived by calculating an average value of past moving direction vectors. It is also effective to derive the moving direction by such a technique, and in particular, when applied to a position detection device that does not have a function of deriving to the directing direction of the capsule endoscope 2, the configuration of this modification is used. By adopting, it is possible to derive the moving direction of the capsule endoscope 2 without having the function of deriving the directivity direction.

(Embodiment 4)
Next, the in-subject introduction system according to the fourth embodiment will be described. The in-subject introduction system according to the fourth embodiment has a function of performing position detection by using geomagnetism instead of the first linear magnetic field.

  FIG. 18 is a schematic diagram illustrating an overall configuration of the intra-subject introduction system according to the fourth embodiment. As shown in FIG. 18, the in-subject introduction system according to the fourth embodiment includes the capsule endoscope 2, the display device 4, and the portable recording medium 5 as in the first to third embodiments. The configuration of the position detection device 68 is different. Specifically, the first linear magnetic field forming unit 9 provided in the position detection device in the first embodiment or the like is omitted, and a geomagnetic sensor 69 is newly provided. The processing device 70 also has a configuration different from that of the first embodiment.

  The geomagnetic sensor 69 basically has the same configuration as the magnetic field sensor 16 provided in the capsule endoscope 2. That is, the geomagnetic sensor 69 has a function of detecting the intensity of the magnetic field component in the predetermined triaxial direction in the arranged region and outputting an electrical signal corresponding to the detected magnetic field intensity. On the other hand, unlike the magnetic field sensor 16, the geomagnetic sensor 69 is disposed on the body surface of the subject 1 and is respectively in the x-axis, y-axis, and z-axis directions of the reference coordinate axes fixed to the subject 1. It has a function of detecting the intensity of the corresponding magnetic field component. That is, the geomagnetic sensor 69 has a function of detecting the advancing direction of the geomagnetism, and outputs an electrical signal corresponding to the magnetic field intensity detected in the x-axis direction, the y-axis direction, and the z-axis direction to the processing device 70. Have

  Next, the processing device 70 according to the fourth embodiment will be described. FIG. 19 is a block diagram illustrating a configuration of the processing device 70. As shown in FIG. 19, the processing device 70 basically has the same configuration as the processing device 12 in the first embodiment, while the geomagnetism on the reference coordinate axis based on the electrical signal input from the geomagnetic sensor 69. And a geomagnetic azimuth deriving unit 71 that outputs a deriving result to the azimuth deriving unit 40.

  A problem that arises when geomagnetism is used as the first linear magnetic field is derivation of the advancing direction of geomagnetism on the reference coordinate axis fixed with respect to the subject 1. That is, since the subject 1 can freely move while the capsule endoscope 2 moves in the body, the positional relationship between the reference coordinate axis fixed to the subject 1 and the geomagnetism. Is expected to change as the subject 1 moves. On the other hand, from the viewpoint of deriving the positional relationship of the target coordinate axis with respect to the reference coordinate axis, when the traveling direction of the first linear magnetic field in the reference coordinate axis is unknown, the reference coordinate axis and the target coordinate axis are related to the traveling direction of the first linear magnetic field. The problem will be that the correspondence cannot be clarified.

  Therefore, in the fourth embodiment, the geomagnetic sensor 69 and the geomagnetic azimuth deriving unit 71 are provided to monitor the advancing direction of the geomagnetism that varies on the reference coordinate axis due to the movement of the subject 1 or the like. That is, based on the detection result of the geomagnetic sensor 69, the geomagnetic azimuth deriving unit 71 derives the traveling direction of the geomagnetism on the reference coordinate axis, and outputs the derived result to the azimuth deriving unit 40. On the other hand, the azimuth deriving unit 40 derives the correspondence between the reference coordinate axis and the target coordinate axis with respect to the direction of geomagnetism by using the input direction of geomagnetism, and combines it with the correspondence in the second linear magnetic field. It is possible to derive azimuth information.

  Depending on the direction of the subject 1, the geomagnetism traveling direction and the second linear magnetic field formed by the second linear magnetic field forming unit 10 may be parallel to each other. In such a case, it is possible to detect the positional relationship by using data on the direction of the target coordinate axis and the position of the origin at the immediately preceding time. Further, in order to avoid that the geomagnetism and the second linear magnetic field are parallel to each other, the extending direction of the coil 34 constituting the second linear magnetic field forming unit 10 is the y-axis direction on the reference coordinate axis as shown in FIG. For example, it is also effective to have a configuration that extends in the z-axis direction.

  Next, advantages of the positional relationship detection system according to the fourth embodiment will be described. The positional relationship detection system according to the fourth embodiment has further advantages by using geomagnetism in addition to the advantages in the first embodiment. That is, by adopting a configuration using geomagnetism as the first linear magnetic field, it is possible to omit the mechanism for forming the first linear magnetic field, and the subject at the time of introduction of the capsule endoscope 2 It is possible to derive the positional relationship of the target coordinate axis with respect to the reference coordinate axis while reducing the burden of 1. Since the geomagnetic sensor 69 can be configured using an MI sensor or the like, the geomagnetic sensor 69 can be sufficiently miniaturized, and the burden on the subject 1 does not increase by newly providing the geomagnetic sensor 69. .

  In addition, by adopting a configuration in which geomagnetism is used as the first linear magnetic field, there is an advantage from the viewpoint of reducing power consumption. That is, when the first linear magnetic field is formed using a coil or the like, the power consumption increases due to the current flowing through the coil, but the use of geomagnetism requires such power consumption. Therefore, it is possible to realize a system with low power consumption.

1 is a schematic diagram showing an overall configuration of an in-subject introduction system according to a first embodiment. It is a typical block diagram which shows the structure of the capsule endoscope with which an in-subject introduction system is equipped. It is a schematic diagram which shows the 1st linear magnetic field formed by the 1st linear magnetic field formation part with which a position detection apparatus is equipped. It is a schematic diagram which shows the aspect of the 2nd linear magnetic field formed by the 2nd linear magnetic field formation part while showing the structure of the 2nd linear magnetic field formation part with which a position detection apparatus is equipped, and a diffusion magnetic field formation part. It is a schematic diagram which shows the aspect of the diffusion magnetic field formed by the diffusion magnetic field formation part. It is a typical block diagram which shows the structure of the processing apparatus with which a position detection apparatus is equipped. It is a schematic diagram which shows the relationship between a reference | standard coordinate axis and an object coordinate axis. It is a schematic diagram which shows the utilization aspect of a 2nd linear magnetic field in the case of position derivation. It is a schematic diagram which shows the utilization aspect of the diffusion magnetic field in the case of position derivation. It is a schematic diagram for demonstrating the derivation | leading-out mode of the possible range using the moving speed and moving speed. It is a schematic diagram for demonstrating the magnetic field formation area | region defined based on the derived possible range. It is a flowchart for demonstrating operation | movement of a processing apparatus. FIG. 4 is a schematic block diagram illustrating a configuration of a processing apparatus provided in an in-subject introduction system according to a second embodiment. It is a schematic diagram which shows an example of the content of the information recorded on the movement speed database. FIG. 6 is a schematic block diagram illustrating a configuration of a processing apparatus provided in an in-subject introduction system according to a third embodiment. FIG. 10 is a schematic diagram for explaining a mechanism for deriving a possible existence range in a third embodiment. FIG. 10 is a schematic diagram for explaining a modification of the in-subject introduction system according to the third embodiment. FIG. 10 is a schematic diagram illustrating an overall configuration of an in-subject introduction system according to a fourth embodiment. It is a typical block diagram which shows the structure of the processing apparatus with which the in-subject introduction system is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subject 2 Capsule endoscope 3 Position detection apparatus 4 Display apparatus 5 Portable recording medium 7a-7d Reception antenna 8a-8d Transmission antenna 9 1st linear magnetic field formation part 10 2nd linear magnetic field formation part 11 Diffusion magnetic field formation part DESCRIPTION OF SYMBOLS 12 Processing apparatus 14 In-subject information acquisition part 15 Signal processing part 16 Magnetic field sensor 17 Amplification part 18 A / D conversion part 19 Wireless transmission part 20 Switching part 21 Timing generation part 22 LED
23 LED drive circuit 24 CCD
Reference Signs List 25 CCD drive circuit 26 transmitting circuit 27 transmitting antenna 28 receiving antenna 29 power regeneration circuit 30 booster circuit 31 capacitor 32 coil 33 current source 34 coil 35 current source 37 receiving antenna selection unit 38 receiving circuit 39 signal processing unit 40 direction deriving unit 41 position Deriving unit 42 Magnetic field direction database 43 Recording unit 44 Oscillator 46 Amplifying circuit 47 Transmitting antenna selection unit 48 Moving speed deriving unit 49 Range deriving unit 50 Magnetic field intensity control unit 51 Power supply unit 52 Curved surface 53 Spherical region 54 Magnetic field forming region 55 Processing device 56 Movement speed database 57 Movement speed deriving section 59 First speed area 60 Second speed area 61 Third speed area 63 Processing device 64 Movement direction deriving section 65 Range deriving section 66 Possible existence area 67 Magnetic field formation area 68 Position detection apparatus 69 Geomagnetic sensor 70 Management device 71 geomagnetic direction deriving unit

Claims (11)

A position detection device that performs position detection of a detection target using a position detection magnetic field having position dependency with respect to intensity at least at a first time and a second time after a predetermined time has elapsed from the first time,
A magnetic field forming means for forming a position detecting magnetic field of variable intensity;
Position deriving means for deriving the position of the detection target based on the intensity of the magnetic field for position detection detected at the position where the detection target exists;
Magnetic field strength control means for controlling the magnetic field forming means based on the position of the detection target at the first time so that the position detection magnetic field becomes detectable by the detection target at the second time;
A position detection device comprising: Based on the position of the detection target at the first time, further comprising range deriving means for deriving a possible range as a range in which the detection target can exist at the second time,
2. The magnetic field intensity control unit controls the magnetic field forming unit to form the position detection magnetic field having a detectable intensity in the possible range derived by the range deriving unit. Position detector. A moving speed deriving unit for deriving the moving speed of the detection target in the predetermined time;
The range deriving means defines a spherical region having a radius of a value obtained by multiplying the moving speed of the detection target by the predetermined time with the position of the detection target at the first time as a center and the existence possible range at the second time. The position detection apparatus according to claim 1, wherein the position detection apparatus is a position detection apparatus. Moving speed deriving means for deriving the moving speed of the detection target in the predetermined time;
A moving direction deriving means for deriving a moving direction of the detection target in the predetermined time;
Further comprising
The range deriving means sets a region including a position moved by a value obtained by multiplying the moving speed and the predetermined time in the moving direction with respect to the position of the detection target at the first time as the existence possible range. The position detection apparatus according to claim 1, wherein   5. The position according to claim 3, wherein the moving speed deriving unit derives the moving speed based on a change in the position of the detection target derived at a plurality of past times by the position deriving unit. Detection device. A moving speed database that records a correspondence relationship between the position of the detection target and the position of the detection target inside the subject;
The moving speed deriving means derives the moving speed of the detection target at the predetermined time using the correspondence recorded in the moving speed database based on the position of the detection target at the first time. The position detection device according to claim 3 or 4.   7. The moving direction deriving unit derives the moving direction of the detection target in the predetermined time based on a change in position detected at a plurality of past times by the position deriving unit. The position detection device according to any one of the above. In the region where the detection target can exist, a first linear magnetic field that linearly travels in a fixed direction with respect to a reference coordinate axis determined independently of the movement of the detection target is formed,
The magnetic field for position detection is a second linear magnetic field that travels linearly in a direction different from the first linear magnetic field and fixed with respect to the reference coordinate axis,
The movement direction deriving means is based on the direction of the detection target determined by the relationship between the target coordinate axis fixed with respect to the detection target and the traveling directions of the first linear magnetic field and the second linear magnetic field. The position detecting device according to any one of claims 4 to 6, wherein the position detecting device is derived.   The position detection device according to claim 8, wherein the first linear magnetic field is formed by geomagnetism.   The position deriving means includes the magnetic field forming means and the detection target based on the strength of the magnetic field formed in the vicinity of the magnetic field forming means by the magnetic field forming means and the strength of the position detection magnetic field detected by the detection target. The position detection apparatus according to claim 1, wherein the position of the detection target is derived using the derived distance. Using the in-subject introduction apparatus introduced into the subject and the position detection magnetic field having position dependency with respect to intensity at least at the first time and at a second time after a predetermined time has elapsed from the first time. An in-subject introduction system provided with a position detection device that detects the position of the introduction device,
The in-subject introduction device comprises:
A magnetic field sensor for detecting at least the strength of the formed magnetic field;
Wireless transmission means for transmitting a wireless signal including information on the magnetic field intensity detected by the magnetic field sensor;
With
The position detection device includes:
A magnetic field forming means for forming a position detecting magnetic field of variable intensity;
Position deriving means for deriving the position of the in-subject introduction device based on the intensity of the position detecting magnetic field detected by the magnetic field sensor extracted from the wireless signal received via a predetermined receiving antenna;
Magnetic field intensity control means for controlling the magnetic field forming means based on the position of the in-subject introduction apparatus at the first time so that the position detection magnetic field has an intensity detectable by the magnetic field sensor at the second time; ,
Intra-subject introduction system characterized by comprising:

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