MEDICAL DEVICE
[TECHNICAL FIELD]
[GO011 The present invention relates to a medical device
including a capsule endoscope capable of being self-propelled
through the inside of a body and a capsule controller that controls
self-propulsion of the capsule endoscope from the outside of the
body.
[BACKGROUND ART]
[00021 Inrecentyears, amedicaldevicethatexaminestheinside
of a body using a capsule endoscope capable of being self-propelled
through the inside of the body is known. The capsule endoscope in
this medical device generally imposes less burden on a subject
because, unlike conventionalendoscopes, it does not require atube
that passes through the gullet or the like for operating the
endoscope. When a subject swallows the capsule endoscope, the
capsule endoscope moves through the inside of the body according
to a peristaltic movement of the stomach or the intestines while
capturing images of the surroundings with an internal camera, and
the captured images are transmitted to a capsule controller that
controls the self-propulsion of the capsule endoscope from the
outside ofthe body andare storedina storagemedium. Thereafter,
the capsule endoscope is discharged outside from the anus.
[0003] Such a self-propelled capsule endoscope can move to a
1
destination to be examined by jiself cis well as moving passively
according to the peristaltic movemer,: . For example, Pateilt
Document 1 discloses a capsule endosccpe in which a magnet having
a magnetization direction in a direction orthogonal to an axial
direction (longitudinal direction) is mounted and a propulsive
power generating portion having a spiral structure is provided at
the rear end in the axial direction. This capsule endoscope is
configured such that the magnet rotates in response to a rotational
magnetic field generated by a capsule controller disposed at the
outside of the body, and the propulsive power generating portion
rotates with rotation of the magnet, whereby propulsive power in
the axial direction is generated.
[0004] Patent Document 2 discloses a capsule endoscope in which
a magnet having a magnetization direction in an axial direction
(longitudinal direction) is mounted and a fin portion is provided
at the rear end in the axial direction. This capsule endoscope is
configured such that the magnet vibrates in response to an
alternating magnetic field generated by a capsule controller
disposed at the outside, and the fin portion vibrates by bending
with the vibration ofthemagnet to push surrounding liquidbackward,
whereby propulsive power in the axial direction is generated. In
Patent Document 2, the position of an electromagnet that generates
a one-directional alternating magnetic field is controlled by a
guide rail and a lift so that the capsule endoscope is moved to
a destination to be examined.
[0005] Since the attitude of the capsule endoscope of Patent
2
Document 2 is stable so that the fin portion bends in the direction
ofthe alternatingmagnetic field, the capsule endoscope can obtain
stable images and perform examinations easily as compared to the
capsule endoscope of Patent Document 1 in which images captured
by the internal camera are likely to rotate or be inclined unstably
withrotationofthepropulsivepowergeneratingportion. Moreover,
since the capsule endoscope of Patent Document 2 can move a large
amount of liquid backward with strong force by means of the fin
portion, it is possible to easily increase the propulsive power
with a small size as compared to the capsule endoscope of Patent
Document 1 in which the propulsive power is obtained by rotation
of the propulsive power generating portion, and to reduce the
possibility that the body walls (wall surfaces inside the body)
are damaged with friction.
[PRIOR ART DOCUMENTS]
[PATENT DOCUMENTS]
[00061 Patent Document 1: Japanese Patent Application
Publication No. 2001-179700
Patent Document 2: Japanese Patent Application
Publication No. 2008-279019
[SUMMARY OF THE INVENTION]
[PROBLEM TO BE SOLVED BY THE INVENTION]
[0007] Such a capsule endoscope that is propelled by vibration
of the fin portion as disclosed in Patent Document 2 has several
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advantages. In themeantime, since thepathalongwhich the capsule
endoscope advances through t h e i n s i d e of the body comes in various
typesincludinga relativelywidearealikethe stomachandacrooked
areas l i k e the i n t e s t i n e s , it is important t o control the moving
d i r e c t i o n of the capsule endoscope. The capsule endoscope
propelled by v i b r a t i o n of the f i n portion can change the moving
d i r e c t i o n thereof by applying a bias magnetic f i e l d i n p a r a l l e l
t o t h e a l t e r n a t i n g magnetic f i e l d .
[0008] However, inthemethodofapplyingthebiasmagneticfield
in p a r a l l e l t o t h e a l t e r n a t i n g magnetic f i e l d , it is not always
easy t o accurately move the capsule endoscope t o a d e s t i n a t i o n t o
beexaminedsincethecapsuleendoscope graduallychangesthemoving
d i r e c t i o n thereof while moving.
[0009] The present invention has been made i n view of the
foregoing, and an object thereof is t o provide a medical device
including a self-propelled capsule endoscope t h a t is propelled
through the inside of a body by v i b r a t i o n of a f i n portion and a
capsule c o n t r o l l e r t h a t controls self-propulsion of the capsule
endoscope from the outside of the body, the medical device being
capableofpreciselycontrollingthemovingdirectionofthecapsule
endoscope e a s i l y .
[MEANS FOR SOLVING THE PROBLEM]
[ O O l O ] In order t o a t t a i n the object, according t o a preferred
embodiment of the present invention, there is provided a medical
device including: a capsule endoscope i n which a magnet having a
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magnetization direction in an axial direction i.s mounted and a fin
portion is provided at a rear end ic the axial direction of an
endoscope main body, and which can be self-propelled through the
inside of a body; and a capsule controller that controls
self-propulsion of the capsule endoscope from the outside of the
body by generating a static magnetic field whose direction is
controlled three-dimensionally and an alternating magnetic field
orthogonal to the static magnetic field, wherein the capsule
endoscope is configured such that the capsule endoscope rotates
upon receiving the static magnetic field so that the magnetization
direction of the magnet is parallel to the direction of the static
magnetic fieldandthe fin portionvibrates bybendingwithmovement
ofthemagnetinresponsetothealternatingmagneticfield, whereby
propulsive power in the axial direction is generated.
[OOll] Preferably, the capsule controller generates the static
magnetic field and the alternating magnetic field by means of a
magnetic field generating portion that includes three sets of
Helmholtz coils. Alternatively, the capsule controller generates
the 'static magnetic field and the alternating magnetic field by
means of a magnetic field generating portion that includes three
sets of coil pairs, and coils that constitute each of the three
sets of coil pairs eachhavea circumferentialshapethatis selected
from a polygonal shape, an elliptical shape, and a circular shape.
In this case, it is preferable that coils that constitute any one
or two sets of the three sets of coil pairs or the three sets of
coil pairs each have a circumferential shape that is an oblong
5
polygonal shape or anelliptical shape. Alternatively, the czpsule
controller generates the staticmagnetic field and the alternating
magnetic fieldbymeans of amagnetic field generating portion that
includes one set of Helmholtz coils and two sets of electromagnets.
[OOlZ] More preferably, the capsule controller is configured
to be able to change an amplitude and/or a frequency of the
alternating magnetic field and/or to change a magnitude of the ..
static magnetic field. In this case, it is preferable that the
amplitude and/or the frequency of the alternating magnetic field
and/or the magnitude of the static magnetic field corresponds to
a turn angle of a terminal, a tilt angle of a joystick, a moving
distance of a lever, or a depression amount of an accelerator.
[0013] Further preferably, the direction ofthe staticmagnetic
field is controlled by an operating unit that uses a handle whose
rotational position can be held, and corresponds to a direction
of a reference point of the handle. In this case, an inclination
angle of the static magnetic field in relation to a horizontal
surface is controlled by changing an inclination angle of a shaft
of the handle or by changing a moving distance of a movable portion
of a slider or a lever. Alternatively, the direction of the static
magnetic field is controlled by an operating unit that uses a
joystick, and a reference point of a joystick platform is rotated
by an angle corresponding to a tilt direction of the joystick, thus
the direction of the static magnetic field corresponds to the
direction of the reference point. In this case, an inclination
angle of the static magnetic field in relation to a horizontal
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surface is controlled by changing a tilt angle of the joystick
platform or by changing a moving d i s t i n c e of a movable poi-t!.on of
a s l i d e r or a lever.
[EFFECTS OF THE INVENTION]
[ 0 0 1 4 ] According t o t h e m e d i c a l device o f t h e p r e s e n t i n v e n t i o n ,
since the moving d i r e c t i o n of the capsule endoscope in t h e i n s i d e
of the body i s controlled according t o the s t a t i c magnetic f i e l d ,
and independently from t h i s , the propulsive power is c o n t r o l l e d
by the alternatingmagnetic f i e l d o r t h o g o n a l t o t h e s t a t i c m a g n e t i c
f i e l d , t h e moving d i r e c t i o n and the moving speed of the capsule
endoscope can be e a s i l y controlled p r e c i s e l y .
[BRIEF DESCRIPTION OF DRAWINGS]
[0015] Fig. 1 is a schematic diagram i l l u s t r a t i n g a
configuration of a medical device according t o an embodiment of
the present invention;
Figs. 2A and 2B are external views i l l u s t r a t i n g a
schematicconfigurationofa capsuleendoscopeofthemedicaldevice,
in which Fig. 2A is a side view and Fig. 2B is a plan view;
Fig. 3 is a plan view schematically i l l u s t r a t i n g an
example of propulsion of the capsule endoscope of the medical
device;
Fig. 4 is a schematic p i c t o r i a l diagram i l l u s t r a t i n g a
c o n f i g u r a t i o n o f amagnetic f i e l d g e n e r a t i n g p o r t i o n o f t h e m e d i c a l
device;
Fig. 5 is a waveform diagram illustrating examples of
amagnetic fleldgeneratedbythemagnetic fieldgenerating portion
of the medical device;
Figs. 6A to 6D are schematic diagrams illustrating
examples of the relationship between the state of a handle of an
operating unit of the medical device and the state of the capsule
endoscope;
Figs. 7A to 7C are schematic diagrams illustrating
examples of inclination of the handle of the operating unit of the
medical device;
Figs. 8A to 8D are schematic diagrams illustrating
examples of the relationship between the state of a joystick of
another operating unit of the medical device and the state of the
capsule endoscope;
Figs. 9A to 9C are schematic diagrams illustrating
examples of inclination of a joystick platform of the operating
unit of the medical device;
Figs. 10A to 10C are diagrams illustrating the
characteristics of one set of coil pairs obtained for use in a
modificationofthemagneticfieldgeneratingportionofthemedical
device;
Figs. 11A to 11C are schematic pictorial diagrams
illustrating one set of coil pairs used when obtaining the
characteristics of Figs. 10A to 10C;
Fig. 12 is a schematic pictorial diagram illustrating
a configuration of a modification of the magnetic field generating
8
portion of the medical device; and
Fig. 13 is a schematic p i c t o r i a l diagram i l l u s t r a t i n g
a configuration of another modification of the magnetic f i e l d
generating portion of the medical device.
[DESCRIPTION OF EMBODIMENTS]
[0016] H e r e i n a f t e r , p r e f e r r e d embodiments of the present
invention w i l l be described w i t h reference t o the drawings. A
medicaldevice1accordingtoanembodimentofthepresentinvention
performs i n t e r n a l examinations or the l i k e of a s u b j e c t , and as
i l l u s t r a t e d i n Fig. 1, includes a capsule endoscope 2 t h a t can be
s e l f - p r o p e l l e d a t t h e i n s i d e o f t h e b o d y o f t h e s u b j e c t a n d a c a p s u l e
c o n t r o l l e r 3 t h a t c o n t r o l s s e l f - p r o p u l s i o n o f t h e capsule endoscope
2 from the outside of the body. The subject is positioned so t h a t
a body portion thereof is located i n s i d e a predetermined range
defined by a magnetic f i e l d generating portion 31 described l a t e r
of the capsule c o n t r o l l e r 3 and is examined a f t e r swallowing the
capsule endoscope 2 from the mouth. The capsule endoscope 2 may
be i n s e r t e d from the anus.
[0017] The capsule endoscope 2 is generally an approximately
c y l i n d r i c a l endoscope t h a t moves in an a x i a l d i r e c t i o n
( l o n g i t u d i n a l d i r e c t i o n ) , and as i l l u s t r a t e d i n Figs. 2A and 2B,
includes an endoscope main body 2a in which a camera 22 or the l i k e
is mounted and a f i n portion 2b in which a magnet 21 having a
magnetizationdirection i n the a x i a l d i r e c t i o n i s m o u n t e d . The f i n
portion 2b is provided a t t h e r e a r end i n t h e a x i a l d i r e c t i o n of
9
the endoscope main body 2a, and specifically, a front end of the
fin portion 2b is fixed to the rear en.i of the endoscope main body
2a directly or with a cap-shaped member or the like interposed.
In the present embodiment, the capsule endoscope 2 has such a size
that a length in the axial direction is approximately 4.5 cm, for
example, and a diameter is approximately 1 cm.
[0018] The structure of the endoscope main body 2a is not the
point of the present invention, and an existing one that is used
in the conventional capsule endoscope can be used. As illustrated
in Figs. 2Aand2B, suchanendoscopemainbody2a generallyincludes,
in addition to the above-described camera 22, a power supply unit
23 that supplies electric power to respective units of the capsule
endoscope 2, an illumination unit 24 that illuminates the outside
in order to allow the camera 22 to capture images, a wireless
communication u n i t 2 5 t h a t w i r e l e s s l y t r a n s m i t s t h e images captured
by the camera 22 to the capsule controller 3, and the like. A front
part (the left part in Figs. 2A and 2B) of the endoscope main body
2a is transparent so that light can pass through the front part.
The camera 22 is constituted of a CCD or the like, the power supply
unit23is constitutedofabatteryorthelike, andthe illuminating
unit 24 is constituted of an LED or the like. The wireless
communication unit 25 may be configured to wirelessly receive a
control signal from the capsule controller 3 to control the camera
22, the illuminating unit 24, and the like.
[0019] Themagnet21 ofthe f i n p o r t i o n 2 b i s a r o d - s h a p e d m a g n e t ,
and as described above, has the same magnetization direction as
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t h e a x i a l d i r e c t i o n of the capsule endoscope 2 . The magnet 21 is
mounted in an e l a s t i c member such as a s i l i c o n r e s i n . The magnet
21 recelves a s t a t i c magnetic f i e l d and an a l t e r n a t i n g magnetic
f i e l d orthogonal to the s t a t i c magnetic f i e l d , generated by a
magnetic f i e l d g e n e r a t i n g portion 31described Later of the capsule
c o n t r o l l e r 3. Uponreceivingthe s t a t i c m a g n e t i c f i e l d , themagnet
21 r o t a t e s so t h a t it i s p a r a l l e l t o t h e d i r e c t i o n of the s t a t i c
magnetic f i e l d . The capsule endoscope 2 r o t a t e s with t h e r o t a t i o n
of the magnet 21. Moreover, the magnet 21 v i b r a t e s i n response t o
thealternatingmagneticfield. Accordingly, as i 1 l u s t r a t e d i n F i . g .
3, the f i n portion 2 b v i b r a t e s bybendingtopush surrounding l i q u i d
backward whereby propulsive power in the a x i a l d i r e c t i o n is
generated.
[0020] Since the f r o n t end of the f i n portion 2b is fixed t o
the endoscope main body 2a and the rear end is open, when the magnet
21 v i b r a t e s , the rear end (the S-pole side i n Figs. 2A and 2B) of
the magnet 2 1 moves g r e a t l y according t o t h e a l t e r n a t i n g magnetic
f i e l d a n d the f r o n t end (the N-pole side i n Figs. 2Aand2B) v i b r a t e s
with a very small amplitude (see Fig. 3 ) .
[00211 The f i n portion 2b has a wide side surface such t h a t it
bends l i k e the f i n of a f i s h t o e f f i c i e n t l y push l i q u i d backward.
The shape of t h e s i d e surface i s a p p r o p r i a t e l y s e l e c t e d . For
example, a p o s t e r i o r p a r t o f t h e side surfacemay have a t r a p e z o i d a l
shape as i l l u s t r a t e d i n Fig. 2A, or the f i n portion 2b may have
agenerallyroundshapeoranoblongshape. Moreover, the thickness
(a width of a surface orthogonal t o the wide side surface) of the
fin portion 2b may be set such that the anterior part thereof is
thin and the posterior part thereof is thinner as illustrated in
Fig. 2B. Or, the entire fin portion 2bnayhave the same thickness.
When an alternating magnetic field is orthogonally incident on the
wide side surface of the fin portion 2b so that the fin portion
2b bends, an attitude of the capsule endoscope 2 is stabilized.
[0022] Next, the capsule controller 3 will be described.. As
illustrated in Figs. 1 and 4, the capsule controller 3 includes
themagnetic fieldgeneratingportion 31that surroundsthe capsule
endoscope 2 from three orthogonal directions. The magnetic field
generating portion 31 consists of three sets of Helmholtz coils
composed of one set of x-axis Helmholtz coils 31x and 31x1 for
generating a magnetic field in an x-axis direction (left-right
direction in Fig. I), one set of y-axis Helmholtz coils 31y and
31y' for generating a magnetic field in a y-axis direction (up-down
direction in Fig. I), and one set~of z-axis Helmholtz coils 312
and 312' for generating a magnetic fie1.d in a z-axis direction
(direction vertical to the drawing sheet in Fig. 1). In Fig. 1,
the subject lies or stands up in parallel to the y-axis direction.
Moreover, inFig. 1, one z-axisHelmholtzcoil31z' islocatedbehind
the other z-axis Helmholtz coil 312.
[0023] The magnetic field generating portion 31 is configured
to generate a static magnetic field that does not change over time
and generate an alternating magnetic field that changes over time
with apredetermined frequencyandamplitude according to a control
current from the magnetic field control unit 32 and to generate
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a combinationofa staticmagnetic fieldandan alternatingmaynetic
field. The static magnetic field and the alternating magnetic
fieldcanbedirectedinany3-dimensional direction. Specifically,
b a s e d o n a c o n t r o l s i g n a l f r o m t h e o p e r a t i n g u n i t 3 3 d e s c r i b e d l a t e r ,
, an x-axis magnetic field control unit 32x of the magnetic field
control unit 32 supplies'such a current that generates an x-axis
directionalmagnetic field component tothe x-axis Helmholtz coils
31x and 31x', a y-axis magnetic field control unit 32y supplies
such a current that generates a y-axis directional magnetic field
component to the y-axis Helmholtz coils 31y and 31y1, and a z-axis
magnetic field control unit 322 supplies such a current that
generates a z-axis directional magnetic field component to the
z-axis Helmholtz coils 312 and 312'.
[0024] The x-axis Helmholtz coils 31x and 31x' have such a
structure that cylindrical coils around which a plurality of wires
is wound are provided concentrically and in parallel so as to be
separated by the same distance R' as a radius R of the coil so that
auniformmagnetic field is generatedata central axis. The x-axis
Helmholtz coils 31x and 31x' are configured to be able to generate
a uniform magnetic field in the x-axis direction at the central
axis by supplying the same directional current to the x-axis
Helmholtz coils 31x and 31x'. Such an iron core as used in an
electromagnet is not used for generating a magnetic field. In
practice, although a small variation generally occurs due to the
width, the thickness, and the installing conditions or the like
of the coils around which a plurality of wires is wound, it is
13
possible to generate a substantially uniformmagnetic field in the
x-axis direction in a space near the central axis. For example,
an allowable variation of the average distance R' in relation to
the average radius R of the coil may be controlled to be within
10% or 20%. The fact that a substantially uniform magnetic field
is generated in a space near the central axis is different from
that of anelectromagnet inwhich themagnetic fieldchanges greatly
depending on the position in the central axis direction. The same
is true for the y-axis Helmholtz coils 31y and 31y' and the z-axis
Helmholtz coils 312 and 312'. Thus, in a certain range near the
center of the magnetic field generating portion 31, the combined
magnetic field is substantially uniform in any direction, and
basically, the capsule endoscope 2 is controlled by the capsule
controller 3 in or near this range. In general, it is necessary
to arrange the x-axis Helmholtz coils 31x and 31x', the y-axis
Helmholtz coils 31y and 31y1, and the z-axis Helmholtz coils 312
and 312' sequentially on the outer side while increasing the radii
andgaps (distances) thereof. Moreover, the radiiandgapsthereof
are not particularly limited, and the order of the radii and gaps
thereof is not limited.
[0025] The staticmagnetic fieldisusedforcontrollingamoving
direction of the capsule endoscope 2. The magnetic field control
unit 32 supplies a direct current to the three sets of Helmholtz
coils of the magnetic field generating portion 31 to generate a
static magnetic field so that the direction of the combined static
magnetic field corresponds to a target moving direction. By doing
14
so, the magnet 21 of the capsule endoscope 2 rotates quickly so
as to be aligned in parallel to tl7e direction of the static magnetic
field, and the capsule endoscope 2 rotates with the rotation so
as to be aligned in a direction identical to the target moving
direction.
to0261 Moreover, the alternating magnetic field is used for
propelling the capsule endoscope 2. The magnetic field control
unit 32 supplies an alternating current to the three sets of
Helmholtz coils of the magnetic field generating poxtion 31 to
generate alternating magnetic field components and controls the
alternatingmagnetic field components so that the direction of the
combined alternating magnetic field is orthogonal to the static
magnetic field. By doing so, themagnet21ofthe capsule endoscope
2 vibrates in a direction approximately orthogonal to the target
moving direction, the fin portion 2b vibrates in a direction
approximately orthogonal to the target moving direction with the
vibration, and as a result, the capsule endoscope 2 is
self-propelled in the target moving direction.
[0027] Here, in a region near the center of the magnetic field
generating portion 31, since the static magnetic field acting on
the capsule endoscope 2 is substantially uniform, the capsule
endoscope 2 just rotates so that the axis of the capsule endoscope
2 is parallel to the direction of the static magnetic field and
is rarely attracted in a specific direction. Thus, it is easy to
control themovingdirection. Moreover, ina regionnear thecenter
of the magnetic field generating portion 31, since the dependence
15
I )
on position of the magnitude of the ,alternating'\Lma,gnetic f i e l d
actingonthecapsuleendoscope 2 i s v e r y s m a l 1 , it is e a s y t o c o n t r o l
the moving speed.
[0028] Althoughthepoint intimewhen t h e s t a t i c m a g n e t i c f i e l d
andthealternatingmagnetic f i e l d a r e g e n e r a t e d i s n o t p a r t i c u l a r l y
limited, since the moving d i r e c t i o n is generally quickly determined
by the s t a t i c magnetic f i e l d , the s t a t i c magnetic f i e l d may be
generated s l i g h t l y e a r l i e r than or simultaneously with the
a l t e r n a t i n g magnetic f i e l d . After the s t a t i c magnetic f i e l d is
generated, the s t a t i c magnetic f i e l d and t h e a l t e r n a t i n g magnetic
f i e l d may be generated simultaneously and combined. For example,
i f the moving d i r e c t i o n is 45", 4 5 O , and 90' with respect t o the
x, y, and z axes, respectively, the x- and y-axis d i r e c t i o n a l
magnetic f i e l d components may be s t a t i c magnetic f i e l d components
of the same values and the z-axis d i r e c t i o n a l magnetic f i e l d may
be an a l t e r n a t i n g magnetic f i e l d a s i l l u s t r a t e d in Fig. 5.
[0029] By changing the amplitude and the frequency of the
a l t e r n a t i n g magnetic f i e l d , the moving speed can be decreased
a c c o r d i n g t o t h e control s i g n a l fromthe o p e r a t i n g u n i t 3 3 described
l a t e r so t h a t the d e t a i l s of the images from the capsule endoscope
Zcanbeobserved, orthepropulsivepowercanbeincreasedaccording
t o t h e c o n t r o l s i g n a l so t h a t the capsule endoscope 2 can e a s i l y
pass through an area where it is d i f f i c u l t f o r the capsule endoscope
2 t o pass. Moreover, by changing the magnitude of the s t a t i c
magnetic f i e l d , themagnitude of forcedirectedtothetargetmoving
d i r e c t i o n can be c o n t r o l l e d according t o t h e c o n t r o l s i g n a l from
16
the operating unit 33 described later 5.j that the capsule endosro]?e
2 can be easily directed in an area tc1:cre it is usually difficult
for the capsule endoscope 2 to be directed to the target moving
direction due to an obstacle or the like. In order to change the
amplitude and the frequency of the alternating magnetic field, the
amplitude and frequency may be adjusted so as to correspond to the
turn angle of a terminal 33a' (see Fig. I) described later or the
tilt angle of a joystick 33b described later. Or, a manually
operated lever (not illustrated) or a foot accelerator (not
illustrated) may be prepared so that the amplitude and frequency
may be adjusted so as to correspond to a moving distance of the
lever or a depression amount ofthe accelerator. Further, in order
to change the magnitude of the staticmagnetic field, the magnitude
of the static magnetic field may be changed whenever the amplitude
and the frequency of the alternating magnetic field are changed,
or may be changed independently by the terminal 33a', the lever,
or the like.
[0030] Moreover, when the alternating magnetic field starts to
be generated, it possibly occurs that the angle between the
vibrating direction of the fin portion 2b and the direction of the
alternating magnetic field is close to orthogonal so that it is
difficult for the fin portion 2b to vibrate. In this case, the
direction of the alternating magnetic field may be changed within
a range where the direction is orthogonal to the static magnetic
field according to the control signal from the operating unit 33.
[0031] In this manner, since the moving direction and the
17
propulsive power (moving speed) of the capsule endoscope 2 can be
controlledindependently, it i s e a s y t ; ~ac curatelymovethe capsule
endoscope 2 t o a d e s t i n a t i o n to be examined.
[0032] Moreover, t h e c a p s u l e c o n t r o l l e r 3 i n c l u d e s t h e . o p e r a t i n g
u n i t 33 t h a t is operated by an examiner as described above. The
operating unit 33 c o n t r o l s t h e moving d i r e c t i o n or the l i k e of the
capsule endoscope 2 using an operating device such as the handle
33a as i l l u s t r a t e d in Figs. 1 and 6A t o 6D or the joystick 33b as
i l l u s t r a t e d i n Figs. 8Ato 8D. The d i r e c t i o n o f t h e s t a t i c m a g n e t i c
f i e l d is controlled based on a signal output by the operating u n i t
33. I n a d d i t i o n t o t h i s , a device t h a t controls the amplitude,
frequency, or d i r e c t i o n o f t h e a l t e r n a t i n g m a g n e t i c f i e l d , a device
t h a t controls the magnitude of the s t a t i c magnetic f i e l d , and the
l i k e may be provided. Moreover, i n the present embodiment, a
communicating unit 34 receives in-vivo images transmitted fromthe
capsule endoscope 2 andthe images are d i s p l a y e d o n a display device
35. Theexaminer c a n o p e r a t e t h e o p e r a t i n g d e v i c e suchas thehandle
33a or the joystick 33b while observing the images.
[0033] The operating unit 33 t h a t uses the handle 33a may be
configured as follows. The handle 33a is configured so t h a t a
rotationalpositionthereofis held. For example, when a reference
point G of the handle 33a is a t the upper side (the position A ' ) ,
the s t a t i c magnetic f i e l d is directed t o the d i r e c t i o n A (see Fig.
6A). The s t a t i c magnetic f i . e l d can r o t a t e s e q u e n t i a l l y from the
d i r e c t i o n A t o t h e d i r e c t i o n s B, C, and D by 90' each. When the
s t a t i c magnetic f i e l d is directed t o the d i r e c t i o n A, the capsule
18
endoscope 2 is directed t o the d i r e r t i o n A. An image from the
capsule endoscope 2 is an image of t h e d i r e c t i o n A. When the
examiner observes the image from the capsule endoscope 2 and wants
the capsule endoscope 2 t o go s t r a i g h t on, the examiner a d j u s t s
the moving speed using the terminal 33a' (see Fig. 1) or the l i k e
without turning the handle 33a.
[OO34] When the examiner observes the image and wants t o change
themoving d i r e c t i o n o f t h e capsule endoscope 2, the examiner turns
the handle 33a leftward or .rightward. For example, when the
examinerobservesthe image andwantstochangethemovingdirection
of the capsule endoscope 2 rightward by 90°, the examiner turns the
handle 33a by 90' rightward. By doing so, the reference p o i n t G
of the handle 33a is positioned a t the r i g h t side ( t h e position
B'); and the s t a t i c magnetic f i e l d is d i r e c t e d t o t h e d i r e c t i o n
B (see Fig. 6B), and the capsule endoscope 2 is d i r e c t e d t o the
d i r e c t i o n B. Similarly, i n a s t a t e where the capsule endoscope 2
is directed t o the position B, when the examiner observes the image
and wants t o change the moving d i r e c t i o n of the capsule endoscope
2 rightwardby 90°, theexaminerturns thehandle 33aby 9O0rightward.
By doing so, the reference point G of the handle 33a is positioned
a t the lower side (the position C ' ) , and the s t a t i c magnetic f i e l d
is d i r e c t e d t o t h e d i r e c t i o n C (see Fig. 6C), and the capsule
endoscope 2 is directed t o t h e d i r e c t i o n C. Similarly, in a s t a t e
where the capsule endoscope 2 is directed t o the position C, when
the examiner observes the image and wants t o change the moving
19
d i r e c t i o n of the capsule endoscope 2 ri.ghtward by 90°, the examiner
t u r n s t h e handle 33a by 90' rightward. By doing so, the reference
point Gofthehandle 3 3 a i s p o s i t i o n e d a t t h e l e f t s i d e ( t h e p o s i t i o n
D'), and the s t a t i c magnetic f i e l d is d i r e c t e d t o the d i r e c t i o n
D (see Fig. 6D), and the capsule endoscope 2 is d i r e c t e d t o the
d i r e c t i o n D.
[00351 Inthismanner, the o p e r a t i n g u n i t 3 3 t h a t u s e s t h e h a n d l e
33a controls the s t a t i c magnetic f i e l d so as to be d i r e c t e d in the
d i r e c t i o n c o r r e s p o n d i n g t o t h e referencepointG, wherebythemoving
d i r e c t i o n toward the l e f t and r i g h t sides of the screen being
observed can be c o n t r o l l e d by the operation ( r o t a t i n g operation)
of the handle 33a. The moving d i r e c t i o n toward the upper and lower
sidesofthescreenobservedmaybecontrolledbychangingthemoving
distance of a movable portion of a s l i d e r 33a" as i l l u s t r a t e d in
Fig. l o r c h a n g i n g a n i n c l i n a t i o n angle of a s h a f t 3 3 a a o f t h e handle
33a as i l l u s t r a t e d i n Figs. 7A t o 7C so t h a t the s t a t i c magnetic
f i e l d can be c o n t r o l l e d t o be a t an optional angle within a range
of -90" and 90' with respect t o a h o r i z o n t a l s u r f a c e . For example,
the s t a t e s of the s h a f t 33aa of the handle 33a, as shown i n Figs.
7A, 7B, and 7C, can be c o n t r o l l e d so as t o correspond t o a case
where the s t a t i c magnetic f i e l d is inclined a t -90°, Oo, and 90'
with respect t o the horizontal surface, respectively. I n place of
the terminal 33a1 or the s l i d e r 3 3 a T ' , another device form may be
n a t u r a l l y f u r t h e r used. For example, a lever may be used instead
of the s l i d e r 33a". Moreover, the reference point G may be
i n v i s i b l e .
[00361 The operating unit 33 t h a t iises the joystick 33b may he
configured as follows. The joystick 13b r o t a t e s the d i r e c t i o n of
the s t a t i c m a g n e t i c fieldcorrespondingtoapositionofa reference
point H of a joystick platform 33b1. The reference point H is
automatically ( o r m a n u a l l y i f n e c e s s a r y ) rotatedbyananglebetween
upper s i d e ( t h e position A t ) and a tilt d i r e c t i o n of. the j o y s t i c k
33b. For example, when the reference point H of the joystick
platform 33b' is a t the upper side (the position A ' ) , the s t a t i c
magnetic f i e l d is directed t o t h e d i r e c t i o n A [see Fig. 8A). The
s t a t i c magnetic f i e l d can r o t a t e s e q u e n t i a l l y from t h e d i r e c t i o n
A t o t h e d i r e c t i o n s B, C, and Dby 9O0each. When t h e s t a t i c m a g n e t i c
f i e l d i s d i r e c t e d t o t h e d i r e c t i o n A, the capsule endoscope 2 is
directed t o the d i r e c t i o n A. An image from the capsule endoscope
2 is an image of t h e d i r e c t i o n A. When the examiner observes the
image from the capsule endoscope 2 and wants the capsule endoscope
2 t o go s t r a i g h t on, the examiner t i l t s the joystick 33b toward
theupper side ( t h e p o s i t i o n A 1 ) . Bydoing so, the capsuleendoscope
2 goes s t r a i g h t on a t a moving speed corresponding t o the tilt
i n c l i n a t i o n angle of the joystick 33b.
100371 When the examiner observes the image and wants t o change
the moving d i r e c t i o n o f t h e capsule endoscope 2, the examiner tilts
the joystick 33b in a desired d i r e c t i o n . For example, when the
examiner observe s t he image andwantsto change themoving d i r e c t i o n
of the capsule endoscope 2 rightward by 90°, the examiner t i l t s the
joystick 33b rightward. By doing so, the joystick platform 33b'
2 1
r o t a t e s so t h a t the reference point H is a t the r i g h t s i d e (the
p o s i t i o n B 1 ) , the s t a t i c m a g n e t i c f i e l d is d i r e c t e d t o t h e d i r e c t i o n
B (see Fig. 8B), and the capsule endcscope 2 is directed t o the
d i r e c t i o n B. Similarly, in a s t a t e where the capsule endoscope 2
is d i r e c t e d t o t h e d i r e c t i o n B, when the examiner observesthe image
and wants t o change the moving d i r e c t i o n of the capsule endoscope
2 rightward by 90°, the examiner moves back the joystick 33b so as
t o stand up and then t i l t s the joysticlc 33b rightward agai.n. By
doing so, the joystick platform 33b' r o t a t e s so t h a t the reference
point H is a t the lower side (the position C ' ) , the s t a t i c magnetic
f i e l d is directed t o t h e d i r e c t i o n C (see Fig. 8C), and the capsule
endoscope 2 is d i r e c t e d t o the d i r e c t i o n C. Similarly, i n a s t a t e
where the capsule endoscope 2 is directed t o the d i r e c t i o n C, when
the examiner observes the image and wants t o change the moving
d i r e c t i o n of the capsule endoscope 2 rightward by 90°, the examiner
moves back the joystick 33b so as t o stand up and then t i l t s the
joystick 33b rightward again. By doing so, the joystick platform
33b' r o t a t e s so t h a t the reference point H is a t the l e f t side (the
position D l ) , t h e s t a t i c m a g n e t i c f i e l d i s d i r e c t e d t o t h e d i r e c t i o n
D (see Fig. 8D), and the capsule endoscope 2 is d i r e c t e d t o the
d i r e c t i o n D.
[00381 In t h i s manner, the operating unit 33 t h a t uses the
j o y s t i c k 3 3 b c o n t r o l s t h e s t a t i c m a g n e t i c f i e l d so as t o b e directed
in t h e d i r e c t i o n corresponding t o the reference point H, whereby
the moving d i r e c t i o n toward the l e f t and r i g h t sides of the screen
being observed can be c o n t r o l l e d by the operation of the joystick
2 2
33b. The moving direction toward the upper and lower sides of the
screen observed may be controlled by ~tsing the slider 33a' ' or the
like described above or by changing the tilt angle of the joystick
platform 33b' as illustrated in Figs. 9A to 9C so that the static
magnetic field can be controlled to be at an optional angle within
a range of -90' and 90' with respect to a horizontal surface. For
example, the state of the joystick platform 33b' in Figs. 9A, 9B,
and 9C corresponds to a case where the st.atic magnetic field is
inclined at -90°, Oo, and 90' with respect to the horizontal surface,
respectively. Note that Figs. 9A to 9C illustrate a state where
the joystick33bstands up. Moreover, inplace ofthe slider 33a1',
another device form (for example, a lever or the like) may be
naturally further used. Moreover, the reference point H may be
invisible.
[00391 An embodiment in which the capsule controller 3 is
configured usingthemagnetic field generating portion 31 has been
described. Since the use ofthe magnetic field generating portion
31 having three sets of Helmholtz coils enables a magnetic field
tobecome substantially uniformas describedabove, it becomes easy
to control the moving direction and the propulsive power (moving
speed). Each set of Helmholtz coils is one set of coil pairs made
up of two coils provided concentrically and in parallel.. When
miniaturization or the like is prioritized, the shape of the coil
of any one or two sets of coil pairs or the three sets of coil pairs
of the magnetic field generating portion 31 having three sets of
Helmholtz coils maybe changed, the size ofthe coil maybe changed,
2 3
and the distance between two coils that constitute the coil. pair
may be changed. In this case, a mag~~etifci eld is not even (not
uniform) but changes depending on a location as will be described
later.
[0040] The characteristics illustrated in Figs. 10A to 10C are
obtained by simulating the magnetic flux density in the y-axis
direction of a magnetic field when one set of coil pairs is disposed
so as to generate a magnetic field in the y-axis direction. The
horizontal axis represents a y-axis coordinate value in which the
center represents the middle of two coils, and a unit length is
L. Figs. 10A, 10B, and 10C illustrate one set of coil pairs so that
the distance between two coils is L, 0.5L, and 2L, respectively.
A curve "a" in the respective drawings illustrates the
characteristics a cylindrical coil the circumferential shape of
which is a circle having a radius of L (see Fig. 11A). Curves "b,"
"c," "d," and "en in the drawings illustrate the characteristics
of a coil the circumferential shape of which is a square having
each side of 2L, a rectangle having a short side of 2L and a long
side of 3L, a rectangle having a short side of 2L and a long side
of 4L, and a rectangle having a short side of 2L and a long side
of 5L, respectively (see Fig. llB). Curves "f," "g," "h," and "in
in the drawings illustrate the characteristics of a coil the
circumferentialshapeofwhichisanoctagonmanufacturedbycutting
all corners of a quadrangle by a length of 0.5L (see Fig. 11C).
The octagons corresponding to the curves "f," "9," "h," and "in
are manufactured from a square having each side of 2L, a rectangle
2 4
having a short side of 2L and a long si.ae of 3L, a rectangle having
a short side of 2L and a long side of 4L, and a rectangle having
a short side of 2L and a long side of SL, respectively. Note that
the curve "a" in Fig. 10A illustrates the characteristics of one
set of Helmholtz coils.
[00411 It can be understood from Figs. l0A to IOC that, when
the shape of the coil is modified to a polygonal shape such as a
quadrangle or an octagon and the distance between two coils is made
different from the distance (the distance between two coils that
c o n s t i t u t e t h e H e l m h o l t z c o i l s ) oftheHelmholtzcoils, themagnetic
field changes depending on a location and the characteristics of
the coils deviate fromthe characteristics of the Helmholtz coils.
On the other hand, it can be understood from Fig. 10A that, when
the distance between two coils is the same as the distance of the
Helmholtz coils, thecloser the size inonedirection the long-side
direction) of a coil to the size in the other direction (the
short-side direction), and the more the number of corners of the
polygonal shape of a coil lager than a quadrangle (that is, the
closer the shape to a circle or an ellipse), the more the
characteristics ofthe coils similar to the characteristics ofthe
Helmholtz coil. Moreover, it can be understood from Figs. 10A to
10C that the more the number of corners of the polygonal shape of
a coil lager than a quadrangle (that is, the closer the shape to
a circle or an ellipse), the larger the magnetic flux density is
obtained. Furthermore, the curves "g," "h," and "i" exhibit
smaller dependence on location ofthemagnetic field than the curve
2 5
"E" in Fig 10c. It canbe understoodthat, when the distance between
two coils is larger than the distance of the Helmholtz coil, the
dependence on location of the magnetic field decreases if the size
in one direction (long-side direction) of a polygon is larger than
the size in the other direction (short-side direction) so that the
size in one direction (long-side direction) of a polygon approaches
the distance between the two coils. In the present application,
a polygon in which the size in one direction is larger than the
size in the other direction orthogonal tothe direction is referred
to as an oblong polygon.
[00421 A magnetic field generating portion 36 includes one set
of Helmholtz coils and two sets of coil pairs obtained by modifying
the structure (the shape and size of coils and the distance between
two coils) of the Helmholtz coils so as to surround the capsule
endoscope 2 from three orthogonal directions. As illustrated in
Fig. 12, in this example, one set of Helmholtz coils is one set
of z-axis Helmholtz coils 362 and 362' that generates a magnetic
field in the z-axis direction. Moreover, the other two sets of coil
pairs are one set of x-axis coil pairs 36x and 36x' that generates
a magnetic field in the x-axis direction and one set of y-axis coil
pairs 36y and 36y' that generates a magnetic field in the y-axis
direction.
[0043] The magnetic field generating portion 36 enables to
decrease an overall size thereof although a change in the magnetic
field depending on the location in the x-axis direction and the
y-axis direction increases as compared to the magnetic field
2 6
generating portion 31. having three set::: of Helmholtz coils, because
it is not necessary in the magnetic field generating portion 36
to arrange a plurality of orthogonal Helmholtz coils so as not to
overlap. It is a little difficult to control the magnetic field
generating portion 36 because the magnetic field in the x-axis
direction and the y-axis direction is not uniform though the
magnetic field in the z-axis direction is uniform. However, it is
possibleto generate the static magnetic field and the alternating
magnetic field in a manner similarly to the magnetic field
generating portion 31 described above and to control the moving
direction and the moving speed of the capsule endoscope 2.
[0044] The coils 36x, 36x1, 36y, and 36y' that constitute the
coil pairs may have a polygonal circumferential shape or an
elliptical or circular circumferential shape that is more similar
to the shape of the Helmholtz coil. When the distance between the
two coils that constitute the coil pair is large, if the coils 36x,
36x1, 36y, and 36y' have such an oblong polygonal or elliptical
circumferential shape that the size in the y-axis direction or the
x-axis direction is larger than the size in the z-axis direction,
it is possible to suppress a change in the magnetic field depending.
on location in the x-axis direction and the y-axis direction while
decreasing the size in the z-axis direction.
[0045] The present invention is not limitedtothemagnetic field
generating portion 36 but can be modified in various ways. For
example, the shape of the coils of any one or two sets of coil pairs
or the three sets of coil pairs of the magnetic field generating
2 7
portion 31 having three sets of Helmholtz coils may be chany-eci arid
the size of the coils and the distance between two coils ;nay be
changed. In this case, the coils that. constitute each of the three
setsofcoilpairseachhaveacircumferentialshapethatis selected
from a polygonal shape, an elliptical shape, and a circular shape.
When the coil has apolygonalcircumferentialshape, a quadrangular
circumferential shape or a polygonal circumferential shape having
more corners than a quadrangle which is preferred from the
perspective of the above-described characteristics can be used.
Moreover, the coilsthat constitute any one or two sets ofthe three
sets of Coil pairs or the three sets of coil pairs may each have
a circumferential shape that is an oblong polygonal shape or an
elliptical shape which is preferred from the perspective of the
above-described characteristics.
[00461 Moreover, a magnetic field generating portion 37 that
includes one set of Helmholtz coils and two sets of electromagnets
so as to surround the capsule endoscope 2 from three orthogonal
directions may be used. As illustrated in Fig. 13, the magnetic
field generating portion 37 includes one set of x-axis
electromagnets 37x and 37x' that generates a magnetic field in the
x-axis direction, one set of y-axis Helmholtz coils 37y and 37y'
that generates a magnetic field in the y-axis direction, and one
set of z-axis electromagnets 372 and 372' that generates amagnetic
field in the z-axis direction. The subject may lie or stand up in
parallel to the y-axis direction.
[0047] Although the magnetic field generating portion 37
2 8
including one set of Helmholtz coils and two sets of electromagnets
isheavyandgenerates amagnetic fieldthat isuneven (not uniform),
since the size of the electromagnet is small, and the radius and
the gap of one set of Helmholtz coils can be freely decreased, it
is possible to decrease the overall size. It becomes a little
difficult to control the magnetic field generating portion 37
because the magnetic field in the x-axis direction and the z-axis
direction is not uniform. However, it is possible to generate the
static magnetic field and the alternating magnetic field and to
control the moving direction and the moving speed of the capsule
endoscope 2.
[00481 While the medical device according to the embodiment of
the present invention has been described, the present invention
can be changed in design in various ways within the scope described
in the claims without being limited to those described in the
embodiment. For example, the structure and the shape of the
endoscopemainbody2a-ofthe capsule endoscope 2maycomeinvarious
types. Moreover, the shapes ofthe handle 33a and the joystick 33b
ofthe operating unit 33 ofthe capsule controller 3 are not limited
to particular shapes, and for example, the handle 33a may have a
dial shape, a knob shape, or a shape of a joystick that does not
stand in addition to the shapes illustrated in Figs. 6A to 6D.
Further, the operating unit 33 of the capsule controller 3 may use
a keyboard, a mouse, a touch panel, and the like of a PC instead
o f t h e h a n d l e 3 3 a , t h e j o y s t i c k 3 3 b ( a n d t h e j o y s t i c k p l a t f o r m 3 3 b ' ) ,
and the like so that the same signal as the control signal output
2 9
from the operating unit 33 according ti' the operation of the handle
33a, the joystick 33b (and the joystick platform 33b1), and the
like is output according to software.
[EXPLANATIONS OF REFERENCE NUMERALS]
[0049] 1 Medical device
2 Capsule endoscope
21 Maqnet
2b Fin portion
3 Capsule controller
31, 36 Magnetic field generating portion
33 Operating unit
33a Handle
33b Joystick
WE CLAIM:
1. A medical device comprising:
a capsule endoscope in which a magnet having a magnetization
d i r e c t i o n i n an a x i a l d i r e c t i o n is mounted and a f i n portion is
provided a t a r e a r end in t h e a x i a l d i r e c t i o n of an endoscope main
body, and which can be self-propelled through t h e i n s i d e of a body;
and
a capsule c o n t r o l l e r t h a t controls self-propulsion of the
capsule endoscope fromthe outside o f t h e b o d y b y g e n e r a t i n g a s t a t i c
magnetic f i e l d whose d i r e c t i o n is controlled three-dimensionally
and an alternatingmagnetic f i e l d orthogonal t o t h e s t a t i c m a g n e t i c
f i e l d , wherein
the capsule endoscope is configured such t h a t t h e capsule
endoscope r o t a t e s upon r e c e i v i n g t h e s t a t i c magnetic f i e l d s o t h a t
the magnetization d i r e c t i o n of the magnet is p a r a l l e l t o the
d i r e c t i o n o f t h e s t a t i c m a g n e t i c f i e l d and the f i n portion v i b r a t e s
bybendingwithmovementofthemagnetinresponsetothealternating
magnetic f i e l d , whereby propulsive power i n the a x i a l d i r e c t i o n
is generated.
2. The medical device according t o claim 1, wherein
the capsule c o n t r o l l e r generates the s t a t i c magnetic f i e l d
and t h e a l t e r n a t i n g magnetic f i e l d by means of a magnetic f i e l d
generating portion t h a t includes three s e t s of Helmholtz c o i l s .
3. The medical device according t o claim 1, wherein
31
the capsule controller generates the static magnetic field
and the alternating magnetic field by means of a magnetic field
generating portion that includes thrze sets of coil pairs, and
coils that constitute each of the three sets of coil pairs
each have a circumferential shape that is selected froma polygonal
shape, an elliptical shape, and a circular shape.
4. The medical device according to claim 3, wherein
coils that constitute any one or two sets of the three sets
of coil pairs or the three sets of coil pairs each have a
circumferential shape that is an oblong polygonal shape or an
elliptical shape.
5. The medical device according to claim 1, wherein
the capsule controller generates the static magnetic field
and the alternating magnetic field by means of a magnetic field
generating portion that includes one set of Helmholtz coils and
two sets of electromagnets.
6. The medical device according to any one of claims 1 to 5,
wherein
the capsule controller is configured to be able to change an
amplitude and/or a frequency of the alternating magnetic field
and/or to change a magnitude of the static magnetic field.
7. The medical device according to claim 6, wherein
3 2
the amplitude a n d / o r t h e frequencyofthe a1ternatingmaqxleti.c
f i e l d a n d / o r t h e m a g n i t u d e o f t h e s t a t i c m a g n e t i c f i e l d corresponds
t o a t u r n angle of a terminal, a tilt angle of a joystick, a moving
distance of a lever, or a depression amount of an a c c e l e r a t o r .
8 . The medical device according t o any one of claims 1 t o 7,
wherein
t h e d i r e c t i o n of the s t a t i c magnetic f i e l d is controlled bv
an operating unit t h a t uses a handle whose r o t a t i o n a l position can
be held, and corresponds t o a d i r e c t i o n of a r e f e r e n c e p o i n t of
the handle.
9. The medical device according t o claim 8 , wherein
an i n c l i n a t i o n angle of the s t a t i c magnetic f i e l d in r e l a t i o n
t o a h o r i z o n t a l s u r f a c e is controlled by changing an i n c l i n a t i o n
angle of a s h a f t of the handle or by changing a moving distance
of a movable portion of a s l i d e r or a l e v e r .
10. The medical device according t o any one of claims 1 t o 7,
wherein
t h e d i r e c t i o n of the s t a t i c magnetic f i e l d is controlled by
an operating unit t h a t uses a joystick, and a reference point of
a joystick platform is r o t a t e d by an angle corresponding t o a tilt
d i r e c t i o n o f t h e joystick, thus t h e d i r e c t i o n o f t h e s t a t i c m a g n e t i c
f i e l d corresponds t o t h e d i r e c t i o n of the reference point.
11. The medical device according to claim 10, wherein
an inclination angle of the static magnetic field in relation
to a horizontal surface is controlled by changing a tilt angle of
the joystick platformor by changing amoving distance of amovable
portion of a slider or a lever.