U.S. patent application number 12/147262 was filed with the patent office on 2008-12-11 for encapsulated medical device guidance system, and method of controlling the same.
This patent application is currently assigned to OLYMPUS MEDICAL SYSTEMS CORP.. Invention is credited to Isao AOKI, Atsushi KIMURA, Akio UCHIYAMA.
Application Number | 20080306340 12/147262 |
Document ID | / |
Family ID | 38218110 |
Filed Date | 2008-12-11 |
United States Patent
Application |
20080306340 |
Kind Code |
A1 |
UCHIYAMA; Akio ; et
al. |
December 11, 2008 |
ENCAPSULATED MEDICAL DEVICE GUIDANCE SYSTEM, AND METHOD OF
CONTROLLING THE SAME
Abstract
An encapsulated medical device guidance system, and a method of
controlling the system, in which guidance coils are arranged to
divide a magnetic field generating plane into at least two front
and rear areas, a magnetic field for canceling gravity applied to a
capsule endoscope itself is formed, and superposed on a magnetic
field for moving or changing an attitude, a frictional resistance
in moving a capsule endoscope is reduced by decreasing an area of
an endoscope to contact the surface of an intracavital.
Inventors: |
UCHIYAMA; Akio;
(Yokohama-shi, JP) ; KIMURA; Atsushi;
(Akiruno-shi, JP) ; AOKI; Isao; (Sagamihara-shi,
JP) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA, SUITE 300
GARDEN CITY
NY
11530
US
|
Assignee: |
OLYMPUS MEDICAL SYSTEMS
CORP.
Tokyo
JP
OLYMPUS CORPORATION
Tokyo
JP
|
Family ID: |
38218110 |
Appl. No.: |
12/147262 |
Filed: |
June 26, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2006/326146 |
Dec 27, 2006 |
|
|
|
12147262 |
|
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Current U.S.
Class: |
600/117 ;
600/118 |
Current CPC
Class: |
A61B 34/73 20160201;
A61B 1/041 20130101; A61B 34/70 20160201; A61B 1/00158
20130101 |
Class at
Publication: |
600/117 ;
600/118 |
International
Class: |
A61B 1/00 20060101
A61B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2005 |
JP |
2005-376277 |
Claims
1. An encapsulated medical device guidance system comprising: an
encapsulated medical device having an internal biological
information acquisition unit to acquire internal biological
information, a communication unit to output the acquired internal
biological information to the outside as an output signal, and a
magnet; a magnetic field generator which acts on the magnet, and
generates a magnetic field for moving the encapsulated medical
device in an objective direction; and a control unit to control the
magnetic field generator in synchronization with the output signal
sent from the communication unit.
2. The system according to claim 1, wherein the control unit stops
driving of the magnetic field generator during the period over
which the output signal is transmitted.
3. An encapsulate d medical device guidance system comprising: an
encapsulated medical device having an internal biological
information acquisition unit to acquire internal biological
information, a communication unit to output the acquired internal
biological information to the outside as an output signal, and a
magnet; a position detector to detect a position of the
encapsulated medical device; and a magnetic field generator which
acts on the magnet, and generates a magnetic field for moving the
encapsulated medical device in an objective direction, wherein the
control unit controls the magnetic field generator in
synchronization with the output signal, and the position detector
detects a position of the encapsulated medical device in
synchronization with the output signal.
4. The system according to claim 3, wherein the control unit stops
driving of the magnetic field generator during the period over
which the output signal is transmitted, and the position detector
detects a position of the encapsulated medical device only during
the period over which the output signal is transmitted.
5. The system according to claim 3, wherein the magnitude of the
magnetic field to be generated from the magnetic field generator is
controlled by adjusting a duration time of a magnetic field.
6. The system according to claim 3, wherein the magnitude of the
magnetic field to be generated from the magnetic field generator is
controlled by adjusting the number of magnetic field pulses.
7. An encapsulated medical device guidance system comprising: an
encapsulated medical device having an internal biological
information acquisition unit to acquire internal biological
information, a communication unit to output the acquired internal
biological information to the outside as an output signal, and a
magnet; a position detector to detect the position of the
encapsulated medical device; a magnetic field generator which acts
on the magnet, and generates a magnetic field for moving the
encapsulated medical device in an objective direction; and a
control unit to control the magnetic field in synchronization with
the output signal, wherein the control unit receives information
about the position and attitude of the encapsulated medical device
detected by the position detector, calculates the direction and
magnitude of a magnetic field generated from the magnetic field
generator, while the output signal is being sent, and controls the
magnetic field generator to generate a magnetic field, while the
output signal is not being sent.
8. The system according to claim 7, wherein a magnetic field
generated by the magnetic field generator has a magnetic
gradient.
9. The system according to claim 7, wherein a magnetic field
generated by the magnetic field generator is a rotational magnetic
field.
10. The system according to claim 7, wherein the magnitude of the
magnetic field to be generated from the magnetic field generator is
controlled by adjusting a duration time of a magnetic field.
11. The system according to claim 7, wherein the magnitude of the
magnetic field to be generated from the magnetic field generator is
controlled by adjusting the number of magnetic field pulses.
12. An encapsulated medical device guidance system comprising: an
encapsulated medical device having an internal biological
information acquisition unit to acquire internal biological
information, a communication unit to output the acquired internal
biological information to the outside as an output signal, and a
magnet; a first magnetic field generator which acts on the magnet,
and generates a magnetic field for moving the encapsulated medical
device in an objective direction; a second magnetic field generator
which acts on the magnet, and generates a magnetic field for
reducing the gravity applied to the encapsulated medical device;
and a control unit to control the first and second magnetic field
generators in synchronization with the output signal.
13. The system according to claim 12, wherein the second magnetic
field generator generates a magnetic field for reducing the
buoyancy applied to the encapsulated medical device.
14. The system according to claim 12, wherein the magnitude of the
magnetic field generated from at least one of the first magnetic
field generator and second magnetic field generator is controlled
by adjusting a duration time of a magnetic field.
15. The system according to claim 12, wherein the magnitude of the
magnetic field generated from at least one of the first magnetic
field generator and second magnetic field generator is controlled
by adjusting the number of magnetic field pulses.
16. An encapsulated medical device guidance system comprising: an
encapsulated medical device having an internal biological
information acquisition unit to acquire internal biological
information, a communication unit to output the acquired internal
biological information to the outside as an output signal, and a
magnet; a magnetic field generator which acts on the magnet, and
generates a magnetic field synthesized from a magnetic field for
moving the encapsulated medical device in an objective direction
and a magnetic field for reducing the gravity applied to the
encapsulated medical device; and a control unit to control the
magnetic field generator in synchronization with the output
signal.
17. The system according to claim 16, wherein the magnetic field
generator is configured to act on the magnet, and generate a
magnetic field synthesized from a magnetic field for moving the
encapsulated medical device in an objective direction and a
magnetic field for reducing the gravity applied to the encapsulated
medical device.
18. A method of controlling a system to guide an encapsulated
medical device for observing an intracavital while moving in an
objective direction in an intracavital based on a detected position
and attitude, by a magnetic field acting on a magnet provided in an
encapsulated medial device, wherein when internal biological
information acquired by the encapsulated medical device in the
intracavital is sent as an output signal, generation of the
magnetic field is stopped in synchronization with the output signal
in the period of sending the output signal.
19. A method of controlling a system to guide an encapsulated
medical device for observing an intracavital while moving in an
objective direction in the intracavital based on a detected
position, by a magnetic field acting on a magnet provided in an
encapsulated medial device, wherein when internal biological
information acquired by the encapsulated medical device in the
intracavital is sent as an output signal, generation of the
magnetic field is stopped, and a position of the encapsulated
medical device is detected in synchronization with the output
signal in the period of sending the output signal.
20. A method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in the intracavital based on a
detected position and attitude, by a magnetic field acting on a
magnet provided in an encapsulated medial device, wherein a
direction and magnitude of the magnetic field to be generated are
calculated based on information about detected position and
attitude of the encapsulated medical device, while the output
signal is being sent, and the magnetic field is generated based on
the calculation result, while the output signal is not being
sent.
21. A method of controlling a system to guide an encapsulated
medical device for observing an intracavital while moving in an
objective direction in the intracavital based on a detected
position and attitude, by a magnetic field acting on a magnet
provided in an encapsulated medial device, wherein the magnitude of
the magnetic field to be generated is controlled by adjusting a
duration time of a magnetic field.
22. A method of controlling a system to guide an encapsulated
medical device for observing an intracavital while moving in an
objective direction in the intracavital based on a detected
position and attitude, by a magnetic field acting on a magnet
provided in an encapsulated medial device, wherein the magnitude of
the magnetic field to be generated is controlled by adjusting the
number of magnetic field pulses.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation application of PCT Application No.
PCT/JP2006/326146, filed Dec. 27, 2006, which was published under
PCT Article 21(2) in Japanese.
[0002] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2005-376277,
filed Dec. 27, 2005, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a guidance system for an
encapsulated medical device inserted into an intracavital for
obtaining internal biological information, and a method of
controlling the same.
[0005] 2. Description of the Related Art
[0006] Among conventional medical devices for obtaining internal
biological information, there is a known encapsulated medical
device which periodically transmits image information while moving
in an intracavital.
[0007] As such an encapsulated medical device, a medical device
guidance system configured to be magnetically induced has been
proposed as disclosed in Jpn. Pat. Appln, KOKAI Publication No.
2004-255174. In this proposal, a medical device guidance system is
inserted into an intracavital, a capsule unit provided with spiral
projections around the perimeter contains a magnet magnetized in
the direction perpendicular to the longitudinal direction, and the
advancing direction of the capsule unit can be smoothly changed by
a magnetic field generated by a magnetic field control unit and a
rotational magnetic field generator based an operating
instructions. By freely changing the capsule unit advancing
direction, the direction of the capsule unit can be changed upon
taking pictures, and an image of a desired part of the intracavital
can be picked up.
[0008] Jpn. Pat. Appln. KOKAI Publication No. 2003-111720 proposes
an apparatus, which takes pictures of an inspection area in the
body of a patient by generating a 3D gradient magnetic field for
determining the positions of a carrier, which contains a linear
magnet and a measuring instrument or a sample collecting device,
and functions as a robot to move freely in the body of a patient,
by moving it in the body under remote control.
BRIEF SUMMARY OF THE INVENTION
[0009] A first encapsulated medical device guidance system
according to an embodiment of the invention has an internal
information acquisition unit to acquire internal biological
information; a communication unit to output the acquired internal
biological information to the outside as an output signal; an
encapsulated medical device having a magnet; a magnetic field
generator which acts on the magnet, and generates a magnetic field
for moving the encapsulated medical device in an objective
direction; and a control unit to control the magnetic field
generator in synchronization with the output signal sent from the
communication unit.
[0010] A second encapsulated medical device guidance system
comprises an internal information acquisition unit to acquire
internal biological information; a communication unit to output the
acquired internal biological information to the outside as an
output signal; an encapsulated medical device having a magnet; a
position detector to detect the position of the encapsulated
medical device; and a magnetic field generator which acts on the
magnet, and generates a magnetic field for moving the encapsulated
medical device in an objective direction; wherein the control unit
controls the magnetic field generator in synchronization with the
output signal, and the position detector detects the position of
the encapsulated medical device in synchronization with the output
signal.
[0011] A third encapsulated medical device guidance system
comprises an internal information acquisition unit to acquire
internal biological information; a communication unit to output the
acquired internal biological information to the outside as an
output signal at regular intervals; an encapsulated medical device
having a magnet; a position detector to detect the position of the
encapsulated medical device; a magnetic field generator which acts
on the magnet, and generates a magnetic field for moving the
encapsulated medical device in an objective direction; and a
control unit to control the magnetic field in synchronization with
the output signal, wherein the control unit receives information
about the position and attitude of the encapsulated medical device
detected by the position detector, calculates the direction and
magnitude of a magnetic field to be generated by the magnetic field
generator, while the output signal is being output, and controls
the magnetic field generator to generate a magnetic field, while
the output signal is not being output.
[0012] A fourth encapsulated medical device guidance system
comprises an internal information acquisition unit to acquire
internal biological information; a communication unit to output the
acquired internal biological information to the outside as an
output signal; an encapsulated medical device having a magnet;
[0013] a first magnetic field generator which acts on the magnet,
and generates a magnetic field for moving the encapsulated medical
device in an objective direction; a second magnetic field generator
which acts on the magnet, and generates a magnetic field for
reducing the gravity applied to the encapsulated medical device;
and a control unit to control the first and second magnetic field
generators in synchronization with the output signal.
[0014] A fifth encapsulated medical device guidance system
comprises an internal information acquisition unit to acquire
internal biological information; a communication unit to output the
acquired internal biological information to the outside as an
output signal; an encapsulated medical device having a magnet; a
magnetic field generator which acting on the magnet, and generates
a magnetic field synthesized from a magnetic field for moving the
encapsulated medical device in an objective direction and a
magnetic field for reducing the gravity applied to the encapsulated
medical device; and a control unit to control the magnetic field
generator in synchronization with the output signal.
[0015] As a sixth embodiment of the invention, there is provided a
method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in an intracavital, by a magnetic
field acting on a magnet provided in an encapsulated medial device,
wherein when internal biological information acquired by the
encapsulated medical device in the intracavital is sent as an
output signal, generation of the magnetic field is stopped in
synchronization with the output signal in the period of sending the
output signal.
[0016] As a seventh embodiment of the invention, there is provided
a method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in the intracavital based on a
detected position, by a magnetic field acting on a magnet provided
in an encapsulated medial device, wherein when internal biological
information acquired by the encapsulated medical device in the
intracavital is sent as an output signal, generation of the
magnetic field is stopped, and a position of the encapsulated
medical device is detected in synchronization with the output
signal in the period of sending the output signal.
[0017] As an eighth embodiment of the invention, there is provided
a method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in an intracavital based on
detected position and attitude, by a magnetic field acting on a
magnet provided in an encapsulated medial device, wherein a
direction and magnitude of the magnetic field to be generated are
calculated based on information about detected position and
attitude of the encapsulated medical device, while the output
signal is being sent, and the magnetic field is generated based on
the calculation result, while the output signal is not being
sent.
[0018] As a ninth embodiment of the invention, there is provided a
method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in an intracavital based on
detected position and attitude, by a magnetic field acting on a
magnet provided in an encapsulated medial device, wherein the
magnitude of the magnetic field to be generated is controlled by
adjusting a duration time of a magnetic field.
[0019] As a tenth embodiment of the invention, there is provided a
method of controlling an encapsulated medical device guidance
system, which is a method of controlling a system to guide an
encapsulated medical device for observing an intracavital while
moving in an objective direction in an intracavital based on
detected position and attitude, by a magnetic field acting on a
magnet provided in an encapsulated medial device, wherein the
magnitude of the magnetic field to be generated is controlled by
adjusting the number of magnetic field pulses.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0020] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention, and together with the general description given
above and the detailed description of the embodiments given below,
serve to explain the principles of the invention.
[0021] FIG. 1 is a diagram showing the configuration of an
encapsulated medical device guidance system according to an
embodiment of the invention;
[0022] FIG. 2 is a sectional view showing the configuration of a
first capsule endoscope according to the embodiment;
[0023] FIG. 3 is a sectional view showing the configuration of a
second capsule endoscope according to the embodiment;
[0024] FIG. 4 is a sectional view showing the configuration of a
third capsule endoscope according to the embodiment;
[0025] FIG. 5 is a sectional view showing the configuration of a
fourth capsule endoscope according to the embodiment;
[0026] FIG. 6 is a sectional view showing the configuration of a
fifth capsule endoscope according to the embodiment;
[0027] FIG. 7 is a view showing an example of a magnetic field
viewed from the Y-axis direction related to guidance, with respect
to the first capsule endoscope;
[0028] FIG. 8 is a timing chart for explaining a first method of
controlling an encapsulated medical device guidance system;
[0029] FIG. 9 is a timing chart for explaining a second method of
controlling an encapsulated medical device guidance system;
[0030] FIG. 10 is a view showing an example of a magnetic field
viewed from the Y-axis direction related to guidance, for
explaining a third method of controlling a encapsulated medical
device guidance system;
[0031] FIG. 11 is a view for explaining an attitude control
considering gravity in a capsule endoscope; and
[0032] FIG. 12 is a view for explaining an attitude control
considering buoyancy in a capsule endoscope.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Hereinafter, embodiments of the invention will be explained
in detail with reference to the accompanying drawings.
[0034] An explanation will be given on an encapsulated medical
device guidance system according to one embodiment of the invention
shown in FIG. 1. This encapsulated medical device guidance system
is largely divided into a capsule endoscope 21 shown in FIG. 2-FIG.
6, and a magnetic guidance unit 1 which generates a magnetic field
for guiding a capsule endoscope. As an encapsulated medical device
in this embodiment, a capsule endoscope 21 is taken and explained
as an example.
[0035] The magnetic guidance unit 1 mainly comprises a guidance
coil group (X1, X2, Y1, Y2, Z1, Z2, D1, D2, D3, D4, D5, D6, D7,
D8), a power supply 2 for guidance coils, a guidance control unit
3, a controller 4, a sense coil unit 5 (5a-5i), a position detector
6, a receiving antenna unit 7 (7a, 7b, 7c), an antenna selector 8,
a receiving unit 9, a display unit 10, a drive coil 11, and a drive
coil driver 12.
[0036] Each of fourteen guidance coils X1, X2, Y1, Y2, Z1, Z2 and
D1-D8 has an air-core electromagnet, and forms an induction
magnetic field generator. In this embodiment, the guidance coils
are arranged in each side of a rectangular parallelepiped. As shown
by the arrow in FIG. 1, the direction of moving the capsule
endoscope 21 forward and backward is assumed to be an X-axis
direction, and the axis horizontally perpendicular to the X-axis
direction is assumed to be a the Y-axis direction, and a
gravitational axis vertically perpendicular to the X-axis direction
is assumed be a Z-axis direction.
[0037] On these axis directions, the guidance coils X1 and X2 are
placed opposing each other around the surfaces of front and rear
sides, forming magnetic lines of force along the X-axis direction,
and becoming vertical to the X-axis. In the describe direction, the
guidance coil X1 side is assumed to be the front, and the guidance
coil X2 side is assumed to be the rear. Moving from the guidance
coil X2 to the guidance coil X1 is assumed to be moving forward,
and moving in the reverse direction is assumed to be moving
backward.
[0038] The guidance coils Y1 and Y2 are placed opposing each other
around the surfaces of both sides, forming magnetic lines of force
along the Y-axis direction, and becoming vertical to the Y-axis
direction. On one of these sides, two guidance coils D3 and D7 are
arranged inside the guidance coil Y1 so as to divide the plane into
two parts, and on the other opposite side, two guidance coils D1
and D5 are arranged inside the guidance coil Y2 so as to divide the
plane into two parts.
[0039] Similarly, the guidance coils Z1 and Z2 are placed opposing
each other around the top and bottom planes with respect to the
Z-axis direction, forming magnetic lines of force along the Z-axis
direction. In the top plane, two guidance coils D4 and D8 are
arranged inside the guidance coil Z1 so as to divide the plane into
two parts, and in the opposite bottom plane, two guidance coils D2
and D6 are arranged inside the guidance coil 32 so as to divide the
plane into two parts. In the describe direction, the guidance coil
Z1 side is assumed to be the top, and the guidance coil Z2 side is
assumed to be the bottom. Moving from the guidance coil Z2 to the
guidance coil Z1 is assumed to be moving upward, and moving in the
reverse direction is assumed to be moving downward.
[0040] An alternating magnetic field formed by the drive coil 11
acts on the magnetic induction coil 31 and generates an induction
current, and a magnetic field is generated from the magnetic
induction coil. This alternating magnetic field includes one or
more frequency components close to a resonance frequency generated
by a coil (magnetic induction coil 31) and capacitor 33 described
later provided in the capsule endoscope 21.
[0041] The generated induction magnetic field is detected by the
sense coils 5a-5i, a signal including the position information is
generated, and the signal is sent to the position detector 6. Based
on this signal, the position detector calculates the position and
posture information in the capsule endoscope 21. The position and
attitude information is sent to the guidance control unit 3, and
used for calculation of a magnetic field to be generated by the
guidance coil group.
[0042] The group of guidance coils X1, X2, Y1, Y2, Z1, Z2, and
D1-D8 is a first magnetic gradient generating means, which
generates a magnetic gradient (a first magnetic gradient) to act on
the magnet (magnetic substance) in the capsule endoscope 21, and
pull the endoscope in a desired direction by moving longitudinally,
horizontally and vertically.
[0043] The guidance coil Z1 eliminates the influence of gravity
when pulling the capsule endoscope 21 in a desired direction by
moving up the endoscope by the above-mentioned guidance coil group,
by generating a magnetic gradient (a second magnetic gradient) to
act on the magnet in the capsule endoscope 21 to cancel the force
of moving down the endoscope moved by the gravity. The guidance
coils D4 and D8 can also generate the same force as the guidance
coil Z1. The guidance coil Z1 is a second magnetic gradient
generating means to eliminate the influence of gravity when moving
the endoscope in a desired direction. On the other hand, the
guidance coil Z2 eliminates the influence of buoyancy when pulling
the capsule endoscope 21 in a desired direction by moving down the
endoscope by the above-mentioned guidance coil group, by generating
a magnetic to act on the magnet in the capsule endoscope 21 to
cancel the force of moving up the endoscope moved by the buoyancy.
The guidance coils D2 and D6 can also generate the same force as
the guidance coil Z2.
[0044] Concretely, the opposingly placed guidance coils X1 and X2,
Y1 and Y2, and Z1 and Z2 generate a uniform magnetic field within
the space surrounded by these guidance coils when a magnetic field
is generated in the same direction, and forms a gradient magnetic
filed when a magnetic field is generated in the opposite direction.
The coils S1-D8 can form a highly uniform magnetic field or a
gradient magnetic field by driving appropriately. Therefore, by
controlling these fourteen guidance coils, it is possible to
generate a magnetic field having desired intensity and gradient
within a desired space.
[0045] In such arrangement of the guidance coil group, in addition
to moving the capsule endoscope 21, longitudinally, horizontally
and vertically, it is possible to incline the endoscope to a
position rising to the front, for example, by generating a magnetic
field to tilt the distal end side up and proximal end side down, by
combining the guidance coils X1, X2, Y1, Y2, Z, Z2 and D1-D8.
[0046] These guidance coils are connected to the power supply 2 for
guidance coils driven individually. The power supply 2 for guidance
coils is controlled by the instruction from the guidance control
unit 3, appropriately supplies power to an guidance coil necessary
for generating a magnetic field, and generates a desired magnetic
field in a desired space.
[0047] In this embodiment, a position detection system (a position
detecting means) for detecting the position information of the
capsule endoscope 21 comprises a drive coil 11 for generating an
induction magnetic field in the coil provided in the capsule
endoscope 21, a sense coil group 5 for detecting the induction
magnetic field generated in the capsule endoscope 21, a position
detector 6 for generating the position information of the capsule
endoscope 21 (the position in three-dimensional space and the
direction of the capsule endoscope) from the signal based on the
induction magnetic field generated by the sense coil group 5, and a
drive coil driver 12 for driving the drive coil 11 according to an
instruction from the position detector 6.
[0048] Nine sense amplifiers 5a-5i constituting the sense coil
group 5 are arranged to be parallel to the side provided with the
guidance coil Y1 and uniform in a plane, so that the correct
position and attitude of the capsule endoscope 21 can be obtained.
In this embodiment, the position related to the Z-axis is detected
by providing a pair of opposingly placed the sense coil group 5 and
drive coil 11. However, for detecting a three-dimensional position
and attitude, it is preferable to provide the pair on each of two
crossing planes, for example, top and side planes. To increase the
detection accuracy, a few more sense coils is preferable.
[0049] The position detector 6 receives an instruction to specify a
position information detection timing from the guidance control
unit 3, and drives the drive coil driver 12 based on the
instruction.
[0050] The drive coil driver 12 generates a magnetic field by
supplying an AC current to the drive coil 11, and generates an
induction magnetic field in the capsule endoscope 21 in the
magnetic field. Each sense coil of the sense coil group 5 detects a
signal based on the induction magnetic field generated from the
capsule endoscope 21, and outputs it to the position detector 6.
The position detector 6 generates the position and attitude
information of the capsule endoscope 21 from the signal based on
the induction magnetic field, and outputs it to the guidance
control unit 3. The guidance control unit 3 determines a desired
moving direction considering the position and attitude information
of the capsule endoscope 21 from the position detector 6, and
instructs the power supply 2 for guidance coils to generate a
magnetic field suitable for moving in that direction. The power
supply 2 for guidance coils feeds a current to the guidance coils
X1, X2, Y1, Y2, Z1, Z2 and D1-D8 according to the instruction from
the guidance control unit 3. Therefore, a magnetic field suitable
for that moving is generated by the guidance coils, and the capsule
endoscope 21 can be smoothly guided.
[0051] The controller 4 is an input unit, which instructs the
advancing direction and gradient of the capsule endoscope 21, by
the operation of an input device by the operator, for example,
tilting a joystick to a desired direction. In addition to a
joystick, buttons arranged to instruct all directions, a touch
panel, or a line-of-sight input unit is available as a means to
operate the controller 4.
[0052] The guidance control unit 3 receives an instruction signal
from the controller 4, position and attitude information from the
position detector 6, and signals related to the driving states of
the guidance coils from the receiving unit 9, calculates a magnetic
force (a magnetic field) for moving the capsule endoscope 21 to a
desired position, determines magnetic forces generated by the
induction coils X1, X2, Y1, Y2, Z1, Z2 and D1-D8 for generating the
magnetic force, and sends an instruction to the power supply for
each guidance coil.
[0053] Further, the guidance control unit 3 stops generation of a
magnetic field during a communication period over which the image
data taken by the capsule endoscope 21 is sent to the receiving
unit 9. At the same time, during this communication period, the
position detector 6 drives the drive coil 11 based on the
instruction from the guidance control unit 3, and acquires position
information from the sense coil group 5.
[0054] Three receiving antennas 7 are connected to the receiving
unit through an antenna selector 8 for selecting the antennas.
These receiving antennas 7 consist of a receiving antenna 7a (AX)
for receiving communication data (internal biological information
including image data) from the X-axis direction, a receiving
antenna 7b (AY) for receiving internal biological information from
the Y-axis direction, and a receiving antenna 7c (AZ) for receiving
internal biological information from the Z-axis direction. The
receiving antennas 7 can detect internal biological information in
three axis directions.
[0055] The antenna selector 8 selects the antennas 7a, 7b and 7c to
be used for communication. The antenna selector 8 receives the
intensity, direction and gradient of a magnetic field generated by
the guidance coil group at the position of each antenna, identifies
a receiving antenna influenced minimum by the magnetic field, and
selects that receiving antenna. By selecting such a receiving
antenna 7, the communication between the receiving unit 9 and
capsule endoscope 21 can be stabilized.
[0056] The receiving unit 9 sends the guidance control unit 3 the
timing of receiving internal biological information from the
capsule endoscope 21. As described above, the guidance control unit
3 stops generation of an induction magnetic field by the guidance
coil group and drive coil 11, during the communication period for
sending internal biological information (image data). Due to this
stoppage, the receiving unit can receive the internal biological
information from the capsule endoscope 21 without being influenced
by an induction magnetic field. By this stop period, the
communication period does not overlap the moving operation and
position detection period, and it is possible to eliminate a noise
in the internal biological information caused by an induction
magnetic field, or an influence of an induction magnetic field on
the receiving antenna.
[0057] Therefore, this stop operation is useful in the point that
image data is not influenced by a noise, and the receiving antenna
is prevented from being influenced by an induction magnetic field,
when a magnetic field generated close to the capsule endoscope 21
has high intensity and much gradient, or when a magnetic field
generated close the receiving antenna 7 has high intensity and much
gradient. Further, even if a magnetic field generated by the
guidance coil has high intensity, the position detector 6 can be
normally operated.
[0058] The display unit 10 consists of a liquid crystal display,
and displays an image taken by the capsule endoscope 21 received
the receiving unit 9. When the image is displayed, the data such as
photographing situation related to the displayed image may be
displayed on the screen together with the image. An explanation
will now be given on first to fifth configuration examples in the
capsule endoscope 21 according to this embodiment with reference to
FIG. 2-FIG. 5.
[0059] FIG. 2 shows the sectional view showing the configuration of
a first capsule endoscope according to the embodiment.
[0060] A capsule case 23 of the first capsule endoscope 21 consists
of a transparent semiround distal end case 23a placed in the front
end side, and a cylindrical proximal end case 23b with a semiround
rear end passing infrared rays. The capsule case 23 contains a
capsule endoscope described later, and is enclosed watertight. The
capsule endoscope 21 advances in the cylinder axial direction
indicated by C in FIG. 2.
[0061] An explanation will be given on the capsule endoscope
itself.
[0062] A main body of the capsule endoscope is largely divided into
an image pickup unit to take pictures of the medial wall surface of
a passage in an intracavital of a patient, a power supply unit to
drive the image pickup unit, an induction magnetic field generator
to generate an induction magnetic field by the above-mentioned
drive coil 11, a magnet to drive the capsule endoscope 21, and a
transmission unit to transmit internal biological information
including acquired image data to the receiving antenna 7.
[0063] The image pickup unit comprises a photographing optics 26
having a fixed-focus lens, an image pickup element 25 consisting of
CMOS or CCD mounted on an image pickup side substrate 24a, an
illumination unit 39 consisting of a light controllable LED
provided close to the photographing optics 26, and an image
processing circuit 27 to perform predetermined image processing for
an image signal from the image pickup element 25 mounted on the
image pickup side substrate 24a in the rear side of the image
pickup element 25. The image pickup side substrate 24a, power
supply side substrate 24b, and front side substrate 43 for a cell
are sealed with adhesive as a single unit 29 fixed with an
adhesive.
[0064] The power supply unit comprises a small cell 32 consisting
of a button cell, a pair of substrate 43 (43a and 43b) for a cell
provided with a not-shown power supply terminal to take out power
from the small cell 32, a heat-shrink tube 34 to fix the small cell
32 just like holding by the cell substrate, a power supply side
substrate 24b whose circuit wiring is electrically connected to the
circuit wiring of the image pickup side substrate 24 by a flexible
substrate, and a power supply circuit 28 provided on the power
supply side substrate 24b and powered by the small cell 32.
[0065] The magnetic field generator comprises a magnet 30 provided
on the perimeter of the adhesive fixed unit 29, a magnetic
induction coil 31 provided through the magnet 30, and a capacitor
33 provided on the substrate for a cell in the front end side,
composing a CL resonance circuit together with the magnetic
induction coil 31.
[0066] The magnetic induction coil 31 is shaped like a ring with a
maximum outside diameter a little smaller than the inside diameter
of the capsule case 23. The magnet 30 converges an external
magnetic field in the magnetic induction coil 31. As a magnet 30, a
material with high saturation magnetic flux density and
permeability, such as amorphous magnet and fine med (HITACHI
KINNZOKU), is suitable. Use of material shaped like a thin film
provides an effect of reducing the volume of magnet when placed in
a capsule endoscope.
[0067] A circular drive magnet 42 is placed on the rear substrate
43b for a cell. As a material of the magnet 42, a neodymium cobalt
is suitable, but not limited to this material. The magnet 42 has an
N-pole magnetized upward and a S-pole magnetized downward, so that
the direction of magnetic lines of force becomes along the Z-axis
direction. By setting the polarity as above, the capsule endoscope
21 is always directed to a predetermined direction with respect to
the guidance coil group of the magnetic guidance unit 1. Therefore,
the top and bottom of an obtained image can be absolutely
determined.
[0068] The transmission unit comprises a communication circuit 36
mounted on the rear side (the magnet 42 side) of a substrate 40 for
transmission, an antenna 37 placed on the front surface side (the
proximal end case 23b), a shielding part 35 to cover the exposed
communication circuit 36 and to shield a magnetic force of the
magnet 42, and an optical switch 38 which is mounted on the
substrate 40 for transmission on the side provided with the antenna
27, and turns on/off the capsule endoscope.
[0069] In such arrangement, the magnetizing direction of the magnet
42 and the direction of the antenna 37 connected to the
transmission circuit 36 are determined by changing the angle by 90
degree. This is done for establishing the condition that the
magnetic field generated by the magnet 42 enters at an angle
displaced 90 degree from the direction of the antenna 37.
Therefore, the influence of the magnetic field from the magnet 42
upon the antenna 37 is reduced to minimum.
[0070] The shielding part 35 is made of magnetic material, and has
an effect to absorb the magnetic field close to the antenna 37.
Therefore, the intensity of the magnetic field applied to the
antenna 37 can be reduced, and the influence of the magnetic field
on the radio communication between the transmission circuit 36 and
antenna 37 can be decreased, and stable radio communication can be
realized.
[0071] The optical switch 38 is sensitive to infrared rays. The
proximal end case 23b of the capsule case 23 is made of material to
pass infrared rays (in the wavelength sensed by the optical switch)
in at least the part close to the optical switch. When infrared
rays are applied to the optical switch 38 from a not-shown infrared
rays emitter, the optical switch turns on power is supplied from
the small cell 32 through the power supply circuit, and
photographing and transmission are started. The circuit of the
optical switch 38 is configured to permit a toggle operation. Once
infrared rays are applied, the capsule endoscope is kept on. It is
permitted to add a configuration, which turns off the endoscope
when infrared rays are applied in the on state.
[0072] By the configuration to cover the communication circuit 36
by the shielding part 35, the influence of the strong magnetic
field of the magnet 42 to the transmission circuit and radio
circuit (e.g., a noise is superposed, or a communicable distance is
reduced) can be reduced. Therefore, clear image data with less
noise can be sent to the receiving unit 9.
[0073] FIG. 3 is a sectional view showing the configuration of a
second capsule endoscope according to the embodiment.
[0074] The second capsule endoscope is provided with a spiral part
41 formed by winding a wire with a circular cross section, on the
perimeter of the capsule case 23, unlike the first capsule
endoscope. The other parts are the same as the first capsule
endoscope, and given the same reference numerals, and an
explanation on these parts will be omitted.
[0075] In this configuration, a revolving magnetic field to the
second capsule endoscope is formed to a guidance coil group by the
drive power supply from the power supply 2 for guidance coils, and
the second capsule endoscope 21 is rotated about the axis C in the
direction R as shown in FIG. 3. The second capsule endoscope 21 is
moved forward or backward along the axis C, according to the
direction of rotating the spiral part 41. Further, as it is
possible to rotate the second capsule endoscope 21 in the tilt
position, the capsule endoscope can be moved forward or backward in
the slanting direction. The second capsule endoscope configured as
above provides the same function and effect as the first capsule
endoscope.
[0076] FIG. 4 is a sectional view showing the configuration of a
third capsule endoscope according to the embodiment.
[0077] The third capsule endoscope is configured by replacing the
positions of the magnet 42 and the magnetic induction coil 31 in
the first capsule endoscope. The other parts are the same as the
first capsule endoscope, and given the same reference numerals, and
an explanation on these parts will be omitted.
[0078] Unlike the ring-shaped induction coil 31 in the first
capsule endoscope, two linear stick-shaped induction coils 52 and
53 are crossed in the third capsule endoscope. FIG. 4 shows an
example of configuration in which the induction coils 52 and 53 are
placed in the directions of axes Z and Y. In the vicinity of the
induction coils 52 and 53, capacitors 54 and 55 are placed to
connect both ends of the induction coils for forming a LC resonance
circuit, and adjusted to obtain a different resonance frequency.
The crossed induction coils 52 and 53 generate an induction
magnetic field by the magnetic field formed by the drive coil 11.
As the induction coils 52 and 53 are vertical to the axis C and
face in different directions, the direction of the axis C (i.e.,
the capsule endoscope advancing direction) can be detected by
obtaining the direction of each induction coil by a respective
resonance frequency. Further, in the third capsule endoscope, a
magnet 51 is arranged along the cylindrical axis (along the axis C)
of the endoscope (with the N-pole set forward and S-pole set
backward). Instead of the circular magnet 42 in the first capsule
endoscope, a ring-shaped magnet or a barrel-shaped arrangement of
stick magnets is provided on the perimeter of the bond fixed part
29. The third capsule endoscope configured as above can provide the
same function and effect as the first capsule endoscope.
[0079] FIG. 5 is a sectional view showing the configuration of a
fourth capsule endoscope according to the embodiment.
[0080] The fourth capsule endoscope is configured by replacing the
magnet 42, transmission circuit 36 and antenna 37 in the first
capsule endoscope. The other parts are the same as the first
capsule endoscope, and given the same reference numerals, and an
explanation on these parts will be omitted.
[0081] In the fourth capsule endoscope, the transmission circuit 36
and antenna 37 are enclosed by the shielding part 62, except the
electromagnetic wave emitting direction of the antenna 37, a window
for an optical switch is opened, and the optical switch 38 is
placed there. A plurality of optical switch 38 may be provided in
different directions. The shielding part is provided adjacent to
the substrate 43b for a cell, and a magnet 63 equivalent to the
magnet 42 in the first capsule endoscope is provided in the rear of
the substrate. A proximal end case 61 of the capsule case 23 is
shaped not semiround, but flat in the rear end. The rear end may be
shaped semiround.
[0082] The fourth capsule endoscope configured as above can provide
the same function and effect as the first capsule endoscope.
Further, with this configuration, the magnetic lines of force close
to the antenna 37 can be decreased in the intensity by penetrating
through the shielding part 62. Therefore, deterioration of
transmission performance can be prevented by reducing the influence
of the magnetic field generated by the magnet 63 on the antenna
37.
[0083] The amount of magnetic flux entering the substrate can be
decreased by evaporating a magnet as a shielding member, or by
using a thin film forming technique such as sputtering. Therefore,
the circuit formed in the capsule endoscope 21 can be prevented
from malfunctioning due to an ill effect of a magnetic field of a
magnet and guidance coil.
[0084] FIG. 6 is a sectional view showing configuration of a fifth
capsule endoscope according to the embodiment.
[0085] In the first capsule endoscope, the internal biological
information (image data) is transmitted wirelessly (by radio waves)
by using the communication circuit 36 and antenna 37. The fifth
capsule endoscope uses a so-called electric field communication
system. Namely, electrodes 64 and 65 exposed to the capsule case
surface are provided, a current signal as internal biological
information is flowed between the electrodes through an
intracavital tissue as an examinee, thereby generating an electric
field in a living organism, and the internal biological information
is received by an electric field sensor fit to the body surface of
a patient, instead of the receiving antenna. The other parts are
the same as the first capsule endoscope, and given the same
reference numerals, and an explanation on these parts will be
omitted.
[0086] With this configuration, radio waves are not used as a
communication medium, an ill effect on the receiving unit and
transmission line is eliminated, a noise is hardly superposed, and
a stable clear image is obtained, in addition to the function and
effect obtained by the first capsule endoscope. Further, the
communication circuit and antenna can be omitted, the configuration
becomes simple, and the capsule case can be miniaturized
furthermore. By providing a speaker in the transmission circuit and
connecting a microphone to the receiving unit, the same function
and effect can be obtained by communication using a sound wave.
[0087] Now, an explanation will be given on a first method of
controlling an encapsulated medical device guidance system
configured as described above.
[0088] FIG. 7 is a view showing an example of magnetic lines of
force in a magnetic field viewed from the Y-axis direction upon
guidance, with respect to the first capsule endoscope shown in FIG.
2. This magnetic field is formed in a space surrounded by the
guidance coils Z1, Z2, D2, D4, D6 and D8. The capsule endoscope is
placed in this space with the distal end facing the direction from
the guidance coil X2 to guidance coil X1 (in the X-axis direction)
shown in FIG. 6.
[0089] In this magnetic field, the guidance coil Z1 generates a
magnetic force upward in the Z-axis direction as shown in the
drawing. The capsule endoscope 21 generates a magnetic field with
the intensity weak in the lower direction (the guidance coil Z2
side) and strong in the upper direction. In the space having such a
magnetic gradient, the magnet 42 in the capsule endoscope 21 is
given an attractive force in the direction of a strong magnetic
field, i.e., upward (called here an upward attractive force).
[0090] Receiving the upward attractive force, the capsule endoscope
21 is moved up in the space. By controlling the strength of the
upward attractive force by the guidance control unit 3, it is
possible to make the state that gravity acting upon the capsule
endoscope 21 is cancelled. At this time, a magnetic field is formed
in the guidance coils D2 and D4 as shown in FIG. 7, and a pulling
force for moving forward is generated. Therefore, when the magnetic
fields of the guidance coils D2 and D4 are superposed on the
magnetic field of the guidance coil Z1, the capsule endoscope 21 is
moved forward while canceling the gravity acting on the endoscope
itself.
[0091] In the prior art, the capsule endoscope 21 is moved with its
own weight (the mass of the capsule endoscope.times.acceleration of
gravity) put on the intracavital tissue. In contrast, in this
embodiment, as the capsule endoscope 21 is reduced in its own
weight, and moved in the state that a reaction force is weakened by
viscosity, the endoscope can be equally moved even by a magnetic
field with a lower intensity. However, if this upward attractive
force is excessively applied, the capsule endoscope 21 is
unnecessarily floated from the intracavital tissue. Once the
capsule endoscope 21 is floated from the intracavital tissue, the
capsule endoscope comes close to the guidance coil Z1, the
attractive force is weakened furthermore, and the capsule endoscope
is suddenly attracted to the guidance coil Z1 and may be floated
over the level desired by the user.
[0092] By controlling as indicated in the timing chart of FIG. 8,
the capsule endoscope is moved while preventing such floating, and
communication of internal biological information can be stably
performed. FIG. 8(a) shows the intensity and generation timing of a
magnetic field generated by the guidance coil Z1 to generate an
upward attractive force in the Z-axis direction. FIG. 8(b) shows
the intensity and generation timing of a magnetic field generated
by the guidance coils D2 and D4 to generate a pulling force in the
X-axis direction. FIG. 8(c) shows the timing for the position
detector 6 to get signals (position and attitude information
signals) based on the induction magnetic field, from each sense
coil 5. FIG. 8(d) shows the timing of photographing internal
biological information, and the timing of transmission and halt of
transmission of internal biological information from the capsule
endoscope 21 to the receiving unit 9. FIG. 8(e) shows the positions
of the intracavital surface and endoscope in the Z-axis
direction.
[0093] In this embodiment, the operation timing shown in FIG. 8 is
set on the basis of the timing of photographing and transmitting
image data by the capsule endoscope 21. The timing is not to be
limited to this, and may be set as appropriate.
[0094] First, the position of the capsule endoscope 21 is detected.
When the position is capsule endoscope 21 sinks below the
intracavital surface (n1 in FIG. 8(e)) and the magnetic field
intensity is lower than a target value, the magnetic field
intensity of the guidance coil Z1 is increased to raise the capsule
endoscope (to n2) at the next timing. At this time, if the capsule
endoscope 21 is excessively raised, the intensity of generated
magnetic field is lowered (n3) at the next timing. The relationship
between the positions of the intracavital surface and capsule
endoscope 21 in the Z-axis direction shown in FIG. 8(e) is
conceptual, and actually, the capsule endoscope 21 substantially
contacts the intracavital surface, and its weight is not
substantially placed on the intracavital surface (the endoscope
does not sink by its own weight).
[0095] At this time, an upward magnetic field in the Z-direction as
shown in FIG. 7 is generated in the guidance coils D2 and D4. This
magnetic field increases the gradient in the direction from the
guidance coil X2 to the guidance coil X1, and becomes a pulling
force for the capsule endoscope 21 to be pulled forward along the
X-axis direction. Therefore, the capsule endoscope 21 is pulled
forward by the guidance coils D2 and D4 with the gravity cancelled
by the magnetic field of the guidance coil Z1, and is smoothly
moved with less friction on the intracavital surface.
[0096] As the capsule endoscope 21 advances, the magnetic field
generated by the guidance coils D2 and D4 is increased in the
gradient at the position of the capsule endoscope, and the pulling
force is increased. Namely, the moving speed of the capsule
endoscope is increased. To move the capsule endoscope 21 at a
constant speed, it is necessary to keep the propulsive force
constant. Therefore, the intensity of the magnetic field generated
in the guidance coils D2 and D4 is gradually decreased as shown in
FIG. 8(b).
[0097] As explained above, the magnetic field intensity is
controlled based on the position information of the capsule
endoscope 21, the gravity applied to the endoscope is cancelled,
and the frictional force acting between the capsule endoscope 21
and intracavital tissue is decreased. By generating a gradient
magnetic field inclined to the direction wanted to move the capsule
endoscope 21 in the state that the gravity is cancelled, the
operation of guiding the endoscope can be made easy by decreasing
the resistance caused by the movement, and the endoscope can be
equally moved by a magnetic field with a lower intensity.
[0098] Next, an explanation will be given to a second method of
controlling an encapsulated medical device guidance system.
[0099] In this second control method, as shown in FIGS. 9(a) and
(b), the intensity of a magnetic field is controlled by the number
of applying an on signal with a predetermined short pulse width to
a drive signal applied to the guidance coils Z1, D2 and D4 in a
period over which one magnetic field is generated. According to
this method, a magnetic field is generated like a pulse in each
guidance coil, the intervals between the generated magnetic fields
are controlled, and the intensity of each magnetic field is
controlled as a result. This is realized by adding a known
switching circuit to the power supply 2 for guidance coils.
[0100] With this configuration, the guidance coils Z1, D2 and D4
generate a magnetic field like a pulse, and the intensity of each
magnetic field is controlled by controlling the intervals between
the generated magnetic fields. By this control, the configuration
of the power supply for guidance coils can be made simple. An
equivalent control method can be realized by using a PWM (Pulse
Width Modulation) control method, which controls the on time (pulse
width).
[0101] Next, an explanation will be given to a third method of
controlling an encapsulated medical device guidance system. The
third control method shown in FIG. 10 realizes similar movement of
the capsule endoscope 21 by driving different combinations of
guidance coils, unlike the first control method. The third capsule
endoscope shown in FIG. 4 is suitable for the third control
method.
[0102] In the third capsule endoscope, the magnet 51 is arranged
along the cylindrical axis (in the direction of the axis C) of the
endoscope (with the N-pole set forward and S-pole set backward).
The magnetic induction coils 52 and 53 are crossed (here,
perpendicular to each other), and each induction coil is also
arranged perpendicular to the direction of the magnetic lines of
force of the magnet 51. Further, in the induction coils 52 and 53
in this embodiment, a wire is wound around a core made of a
needle-like magnet, and the capacitors 54 and 55 are connected to
the induction coils. The L-component or C-component of these two
induction coils 52 and 53 is adjusted to have different resonance
frequencies.
[0103] In such a configuration, the direction of magnetic lines of
force from the magnet 51 can be arranged to be vertical to the
longitudinal direction of the induction coils 52 and 53, and the
influence of the magnetic field from the magnet 51 can be reduced
to minimum, and the direction of the capsule endoscope can be
determined by detecting the directions of two induction coils 52
and 53.
[0104] The magnet incorporated in the capsule endoscope 21 shown in
FIG. 10 is faced to the advancing direction (in the X-direction
shown in FIG. 10) of the capsule endoscope 21, but the same control
as shown in FIG. 7 is possible by adding a magnetic field as shown
in FIG. 10. Namely, by generating a gradient magnetic field with
the intensity gradually increased in the Z-axis direction (upward)
by the guidance coils D4 and D8, an attractive force opposed to
gravity is formed, and a gradient magnetic field is generated with
the intensity gradually increased in the X-direction from the
guidance coil X (the direction to the left side), and the capsule
endoscope 21 can be moved in the X-direction with the gravity
decreased.
[0105] Next, an explanation will be given on the attitude control
of the capsule endoscope 21 by referring to FIG. 11.
[0106] An explanation will be given by using the magnetic guidance
unit 1 shown in FIG. 1 and the third capsule endoscope 21 shown in
FIG. 4.
[0107] First, an explanation will be given on the attitude of the
capsule endoscope 21 inclined from the horizontal direction, for
example, the tilt position where the distal end portion of the
endoscope is raised, and the proximal end portion contacts the
digestive organs. To take this position, a first magnetic field
advancing upward in the Z-axis direction is generated by using the
guidance coils Z1 and Z2 among fourteen guidance coils X1, X2, Y,
Y2, Z1, Z2, and D1-D8, and a second magnetic field advancing to the
left side in the X-axis direction is generated by using the
guidance coils X1, and X2. It is possible to inline only the first
magnetic field generated by the guidance coils Z1 and Z2. A
magnetic field synthesized from the first and second magnetic
fields is an external magnetic field H in FIG. 11. However, as
gravity acts on the capsule endoscope 21, the capsule endoscope 21
does not become parallel to the external magnetic field H. At this
time, magnetization of the magnet 42 is assumed to be M, the
external magnetic field is assumed to be H, the angle formed by M
and H is assumed to be .delta., the mass of the capsule endoscope
21 is assumed to be m, the gravity acceleration is assumed to be g,
the angle formed by the Z-direction and the direction of the
capsule endoscope 21 is assumed to be .theta., the gravity of the
capsule endoscope 21 is assumed to be G, the pivot of rotation when
the capsule endoscope 21 is faced upward and .theta. is changed is
assumed to be P, and the distance from the pivot P is assumed to be
1. At this time, for simplicity, the pivot P can be the center of
the semiround shape of the exterior end portion on the side not
provided with the image pickup optics 26 in the capsule endoscope
21. By using the above defined items, the following equation is
established.
.delta. = sin - 1 ( mgl sin .theta. H M ) [ Equation 1 ]
##EQU00001##
[0108] According to the equation, a magnetic field may be added in
the direction of .THETA.=.theta.-.delta. to direct the capsule
endoscope 21 to the .theta. direction. A magnetic field generated
by the guidance coil group is controlled in this way. By adding a
magnetic field in the .THETA. direction, the capsule endoscope 21
can be directed to a desired direction (the .theta. direction)
without being influenced by gravity. When an electric field is
formed in the guidance coil X1 to generate an attractive force to
pull in the forward direction, for example, while the capsule
endoscope 21 is existing in the tilt position in such a magnetic
field, the capsule endoscope 21 is moved forward while keeping the
tilt position in the state that only the proximal end portion of
the capsule case 23 contacts the medial wall of the digestive
organs. By moving in this way, the capsule endoscope easily rides
over an uneven spot on a pathway on the medial wall of the
digestive organs. Further, by superposing an electric field to
cancel gravity by using the guidance coil Z1, the capsule endoscope
can be moved with a decreased frictional force.
[0109] When water remains in the intracavital, buoyancy larger than
gravity may be generated. In such a state, the capsule endoscope is
inclined to a position with the side having a heavier specific
gravity to water faced downward, and photographing of a desired
part may become difficult. Therefore, in this embodiment, a desired
position is realized by forming magnetic fields by a plurality of
guidance coil. For example, when water remains on the medial wall
of the digestive organs and the distal end of the capsule endoscope
21 is floated, a guidance coil group X1/X2 and Z1/Z2 are used to
incline the capsule endoscope to the position as shown in FIG. 12.
Namely, the guidance coils Z1 and Z2 are used to form a third
magnetic field toward the Z-axis downward, and the guidance coils
Z1 and Z2 are used to form a fourth magnetic field toward the
X-axis direction. By these magnetic fields, even if the distal end
or proximal end portion of the capsule endoscope 21 is floated by
buoyancy, the position can be easily controlled and a desired part
can be taken as an image.
[0110] As explained herein, in the capsule endoscope system
according to the invention, a magnetic field to cancel the gravity
applied to the capsule endoscope is formed, the magnetic field is
superposed on a magnetic field to move the capsule endoscope or
change the attitude of the capsule endoscope, the whole endoscope
is floated to reduce the area to contact the intracavital surface,
and a frictional resistance is decreased. Therefore, the capsule
endoscope can be easily operated and controlled, an error in
movement caused by gravity and sensed by the operator when the
capsule endoscope is moved or the attitude of the endoscope can be
eliminated, and the operation corresponding to the operating amount
can be realized.
[0111] Further, as the magnetic fields generated from the position
detector and guidance coils are controlled in synchronization with
data transmission with the capsule endoscope, the data transmission
and position detection can be made without being influenced by the
magnetic fields generated by the guidance coils, and the stability
of the encapsulated medical device guidance system is improved.
[0112] By controlling the attitude of the capsule endoscope, the
capsule endoscope can be moved in the start-up tilt position with
the distal end directed upward, and can easily ride over even an
uneven area difficult to move on the intracavital surface on the
pathway. Such movement in the tilt position with the distal end or
proximal end portion contacting the intracavital surface can be
realized by a magnetic field with the intensity lower than a
magnetic field for floating the whole capsule endoscope, and a
large output of a power supply for guidance coils is not required,
and the capsule endoscope can be miniaturized.
[0113] The present invention is not limited to the described
embodiments. Numerous modifications are possible without departing
from the spirit and essential characteristics of the invention. Not
all components of the embodiments may be mounted, and only the
executable components may be used.
[0114] The present invention provides an encapsulated medical
device guidance system, which generates a magnetic field
environment for an encapsulated medical device to face to a desired
direction, eliminates an error in movement caused by gravity acting
during operation, decreases a frictional resistance, and works
appropriately by a weak attractive force.
* * * * *