U.S. patent application number 13/192503 was filed with the patent office on 2011-11-17 for capsule endoscope apparatus.
This patent application is currently assigned to OLYMPUS CORPORATION. Invention is credited to Jun Hasegawa, Ryoko Inoue, Hirokazu Nishimura, Hideki Tanaka.
Application Number | 20110282145 13/192503 |
Document ID | / |
Family ID | 34792181 |
Filed Date | 2011-11-17 |
United States Patent
Application |
20110282145 |
Kind Code |
A1 |
Hasegawa; Jun ; et
al. |
November 17, 2011 |
CAPSULE ENDOSCOPE APPARATUS
Abstract
A signal processing circuit of an external device includes a CPU
and a memory which are not shown. A program for estimating at least
one of the position and orientation of a capsule endoscope on the
basis of strength signals received through respective antennas is
installed in the signal processing circuit. A single-core coil to
generate a magnetic field is arranged in the capsule endoscope. The
generated magnetic field is detected by a plurality of coils
arranged outside a body, whereby a distance that the capsule
endoscope has traveled can be obtained with accuracy. This
arrangement controls image-capture timing to reliably capture
images necessary for a diagnosis and prevent unnecessary image
capture.
Inventors: |
Hasegawa; Jun; (Tokyo,
JP) ; Nishimura; Hirokazu; (Tokyo, JP) ;
Tanaka; Hideki; (Tokyo, JP) ; Inoue; Ryoko;
(Tokyo, JP) |
Assignee: |
OLYMPUS CORPORATION
Tokyo
JP
|
Family ID: |
34792181 |
Appl. No.: |
13/192503 |
Filed: |
July 28, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11485563 |
Jul 12, 2006 |
7988620 |
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13192503 |
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PCT/JP05/00342 |
Jan 14, 2005 |
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11485563 |
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Current U.S.
Class: |
600/109 |
Current CPC
Class: |
A61B 1/00009 20130101;
A61B 1/00036 20130101; A61B 1/041 20130101; A61B 5/061 20130101;
A61B 5/073 20130101; A61B 1/273 20130101; A61B 2560/0456 20130101;
A61B 1/31 20130101; A61B 1/00016 20130101; A61B 5/6805
20130101 |
Class at
Publication: |
600/109 |
International
Class: |
A61B 1/04 20060101
A61B001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2004 |
JP |
2004-007379 |
Claims
1. A capsule endoscope apparatus comprising an image capturing unit
for capturing an image in a body to transmit the image by radio and
a receiving unit for receiving the image transmitted by radio from
the image capturing unit to record the image, the apparatus further
comprising: an estimating unit for receiving a signal transmitted
by radio from the image capturing unit through each of a plurality
of antennas arranged at different positions outside the body to
estimate at least one of the position and orientation of the image
capturing unit on the basis of the signals received through the
antennas; and a control unit for controlling image capture by the
image capturing unit using information regarding at least one of
the position and orientation estimated by the estimating unit.
2. The capsule endoscope apparatus according to claim 1, wherein
the control unit includes: a distance calculating unit for
calculating a distance that the image capturing unit has traveled
on the basis of a plurality of positions of the image capturing
unit obtained by the estimating unit; and an image-capture control
unit for controlling image capture by the image capturing unit on
the basis of the distance.
3. The capsule endoscope apparatus according to claim 2, wherein
the distance calculating unit includes a unit for calculating a
predicted distance on the basis of the plurality of positions of
the image capturing unit obtained by the estimating unit.
4. The capsule endoscope apparatus according to claim 3, wherein
the predicted distance is calculated using an approximation
function derived from the plurality of positions of the image
capturing unit obtained by the estimating unit.
5. The capsule endoscope apparatus according to claim 2, wherein
the control unit includes: an orientation-change calculating unit
for calculating a change in orientation of the image capturing unit
on the basis of a plurality of orientations obtained by the
estimating unit; and an image-capture control unit for controlling
image capture by the image capturing unit on the basis of the
distance and the change in orientation.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of U.S.
application Ser. No. 11/485,563 filed on Jul. 12, 2006, which is a
continuation application of PCT/JP2005/000342 filed on Jan. 14,
2005 and claims benefit of Japanese Application No. 2004-007379
filed in Japan on Jan. 14, 2004, the entire contents of each of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a capsule endoscope
apparatus comprising an ingestible capsule unit and an
extracorporeal unit for receiving biological information
transmitted from the capsule unit.
[0004] 2. Description of the Related Art
[0005] In recent years, capsule endoscope apparatuses for
conducting an examination and the like in a body cavity with an
ingested capsule type unit have been proposed.
[0006] For example, Japanese Unexamined Patent Application
Publication No. 7-111985 discloses an apparatus including a
spherical capsule divided in two having communication means for
transmitting biological information to an extracorporeal
device.
[0007] PCT Publication No. WO 01/87377 A2 discloses a capsule
endoscope apparatus for detecting the motion (rate) of a capsule
unit through an acceleration sensor or the like disposed in the
capsule unit to control a capture rate or a display rate on the
basis of a detected value.
SUMMARY OF THE INVENTION
[0008] The present invention provides a capsule endoscope apparatus
including an image capturing unit for capturing an image in a body
to transmit the image by radio and a receiving unit for receiving
the image transmitted by radio from the image capturing unit to
record the image, the apparatus further including: an estimating
unit for receiving a signal transmitted by radio from the image
capturing unit through each of a plurality of antennas arranged at
different positions outside the body to estimate at least one of
the position and orientation of the image capturing unit on the
basis of the signals received through the antennas; and a control
unit for controlling image capture by the image capturing unit
using information regarding at least one of the position and
orientation estimated by the estimating unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A and FIG. 1B include explanatory diagrams showing the
structure of a capsule endoscope apparatus according to a first
embodiment of the present invention and that of an extracorporeal
device, such as an extracorporeal terminal, FIG. 1A being the
explanatory diagram showing the capsule endoscope apparatus, FIG.
1B being the explanatory diagram showing the structure of the
extracorporeal device, such as an extracorporeal terminal.
[0010] FIG. 2 is an explanatory diagram showing the internal
structure of a capsule endoscope shown in FIG. 1A.
[0011] FIG. 3 is an explanatory diagram showing single-core coils
serving as antennas of an antenna unit in FIG. 1A.
[0012] FIG. 4 is an explanatory diagram showing the structure of a
signal transmitting and receiving function for an antenna of the
capsule endoscope of FIG. 2 and that for the antennas of the
antenna unit in FIG. 1.
[0013] FIG. 5 is a diagram explaining signals transmitted from the
antenna of the capsule endoscope of FIG. 2.
[0014] FIG. 6 is a first diagram explaining a process by a signal
processing circuit in FIG. 4.
[0015] FIG. 7 is a second diagram explaining the process by the
signal processing circuit in FIG. 4.
[0016] FIG. 8 is a diagram explaining a process by a signal
processing circuit according to a second embodiment of the present
invention.
[0017] FIG. 9 is a diagram explaining a process by a signal
processing circuit according to a third embodiment of the present
invention.
[0018] FIG. 10 is a block diagram showing the structure of an image
capturing circuit of a capsule endoscope according to a fourth
embodiment of the present invention.
[0019] FIG. 11 is a flowchart showing the flow of a process
executed by a signal processing circuit in an external device
according to a sixth embodiment of the present invention.
[0020] FIG. 12 is a flowchart showing the flow of a process
performed by a terminal according to a seventh embodiment of the
present invention.
[0021] FIG. 13 is a first diagram showing an example of a screen
displayed on the terminal by the process of FIG. 12.
[0022] FIG. 14 is a second diagram showing an example of a screen
displayed on the terminal by the process of FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0023] Embodiments of the present invention will now be described
below with reference to the drawings.
First Embodiment
Structure
[0024] FIG. 1A is an explanatory diagram showing the entire
structure of a capsule endoscope apparatus 1 according to the
present embodiment. Referring to FIG. 1A, the capsule endoscope
apparatus 1 includes a capsule endoscope 3, ingested by a patient
2, for examining a patient's body cavity and an external device 5
disposed outside the body of the patient 2, the external device 5
serving as a receiver connected to an antenna unit 4 for receiving
image information captured by the capsule endoscope 3 by radio.
[0025] According to the present embodiment, the image information,
transmitted from the capsule endoscope 3 and received by the
external device 5, is recorded on portable memory means, e.g., a
Compact Flash (registered trademark) memory, which will be
described later, installed in the external device 5 during the
examination of the body cavity. Alternatively, the image
information is downloaded into a terminal 7, e.g., a personal
computer, through a USB cable or the like (not shown). In addition,
placing the external device 5 on a cradle 6 electrically connects
the external device 5 to the terminal 7.
[0026] When viewer software for observation is executed in the
terminal 7 shown in FIG. 1B, the image information stored in the
external device 5 can be downloaded into a terminal body 9 by
operating an input control device, such as a keyboard 8a or a mouse
8b, whereby downloaded images can be displayed on a monitor 8c.
[0027] As shown in FIG. 1A, in a case where the patient 2 swallows
the capsule endoscope 3 for endoscopy, the antenna unit 4 including
a plurality of antennas 11 is attached to a jacket 10 that the
patient 2 wears. The antenna unit 4 receives signals, which are
obtained by image capture through the capsule endoscope 3 and are
transmitted from an antenna 23 (refer to FIG. 2) built in the
capsule endoscope 3. The external device 5, connected to the
antenna unit 4, can store captured images. The external device 5 is
attached to, e.g., a belt of the patient 2 through a hook
detachable from the belt. The antenna unit 4 may be stuck directly
on the patient's body.
[0028] In the antenna unit 4, each antenna 11 includes single-core
coils different in position and orientation. For example,
single-core coils 11aX, 11aY, . . . , 11dY, and 11dZ aligned with
the coordinate axes representing X, Y, and Z coordinates as shown
in FIG. 3 are available.
[0029] The external device 5 has, e.g., a box shape. The front face
thereof incorporates a liquid crystal monitor 12 for image display
and an operation section 13 for instructions and operations.
[0030] Alternatively, the external device 5 may include an LED for
alarm display and a power switch alone, the alarm display being
concerned with the remaining amount of a battery, the power switch
serving as the operation section 13. In this case, a portable
display (viewer), which is not shown, for processing image signals
transmitted from the capsule endoscope 3 to display images on a
liquid crystal monitor equipped therewith may be connected as a
second external device to the external device 5.
[0031] Referring to FIG. 2, the capsule endoscope 3 includes an
outer housing 14 shaped in a cylinder, whose rear end is closed,
and a substantially semispherical, i.e., domed cover 14a connected
to the front end of the cylinder with an adhesive to provide a
capsule structure. Accordingly, the capsule endoscope 3 has a
watertight structure.
[0032] In the domed cover 14a that is transparent, an objective
lens 15 for forming an image of incident light received through the
domed cover 14a is attached to a lens frame 16 such that the
objective lens 15 is positioned in the center of the section of the
cylinder. An image capturing element, e.g., a CCD imager 17 is
disposed in the image forming position of the objective lens
15.
[0033] As an illumination system, e.g., four white LEDs 18 are
arranged around the objective lens 15 on the same plane.
[0034] In addition, a processing circuit 19 for driving the white
LEDs 18 to emit light and driving the CCD imager 17 to execute a
process of generating image signals from signals captured by the
CCD imager 17, a communication processing circuit 20 for
transmitting the image signals, and button batteries 21 for
supplying power to the circuits 19 and 20 are arranged on, e.g.,
the rear of the CCD imager 17 within the outer housing 14.
[0035] On the rear of the button batteries 21, i.e., in the other
semispherical end, the antenna 23 for transmitting and receiving
radio waves is arranged so as to connect to the communication
processing circuit 20. The CCD imager 17, the white LEDs 18, and
the circuits are mounted on respective substrates (not shown) and
the substrates are connected via a flexible substrate.
[0036] In the capsule endoscope 3, the processing circuit 19
generates a control signal to control image-capture timing of the
CCD imager 17. In normal image capture, two frame images are
captured per second. In a region, such as esophagus, where the
capsule endoscope moves at a relatively high rate, e.g., 15 to 30
frame images are captured per second. The antenna 23 receives a
signal transmitted from the external device 5. The communication
processing circuit 20 processes the received signal and supplies
the resultant signal to the processing circuit 19. The processing
circuit 19 controls image-capture timing of the CCD imager 17 and
turn-on/off of the white LEDs 18 in response to the supplied
signal.
Operation
[0037] In the capsule endoscope 3, as shown in FIG. 4, the
processing circuit 19 outputs an image signal and a signal
indicative of a signal strength which are shown in FIG. 5. The
communication processing circuit 20 transmits the signals at a
predetermined radio-field intensity through the antenna 23 to the
external device 5. In the external device 5, a transmitting and
receiving circuit 33 receives the signals through each of the
antennas 11ax, 11aY, . . . , 11dY, and 11dZ of the antenna unit
4.
[0038] The transmitting and receiving circuit 33 supplies the image
signals and the strength signals to a signal processing circuit 35.
The signal processing circuit 35 compares the strengths of the
strength signals received through the respective antennas 11ij.
Consequently, the signal processing circuit 35 detects the antenna
most suitable to receive the image signal transmitted from the
capsule endoscope 3. The signal processing circuit 35 supplies the
image signal received through the most suitable antenna to memory
means 47, such as a Compact Flash (registered trademark) memory (CF
memory) or a hard disk, connected to the signal processing circuit
35 to store the image signal. Furthermore, the signal processing
circuit 35 supplies the image signal received through the most
suitable antenna to the liquid crystal monitor 12 connected to the
signal processing circuit 35 to display an image captured through
the capsule endoscope.
[0039] In the external device 5, the signal processing circuit 35
includes a CPU and a memory, which are not shown. A program for
estimating the position and orientation of the capsule endoscope 3
on the basis of the strength signals received through the antennas
11ij is installed in the signal processing circuit 35. The position
and orientation thereof can be estimated using a method for solving
a plurality of nonlinear equations disclosed in Japanese Unexamined
Patent Application Publication No. 11-325810. The signal processing
circuit 35 obtains 12 nonlinear equations, in which the positions
and orientations of the single-core coils arranged in the capsule
endoscope 3 are unknown, from the strength levels of the strength
signals received through the antennas 11ax, 11aY, . . . , 11dY, and
11dZ. The 12 nonlinear equations are solved by iterative
refinement, e.g., the Gauss-Newton method, whereby the position and
orientation of the capsule endoscope 3 is estimated. The estimated
position and orientation are represented by coordinate values with
respect to the antenna unit 4 in FIG. 3. The coordinate values are
stored together with the image signal in the memory means 47. It
is, however, unnecessary to estimate both of the position and the
direction. Either of them may be estimated.
[0040] Assuming that the position of the capsule endoscope 3 is
represented by Pi(Xi, Yi, Zi) as shown in FIG. 6, a distance Di
that the capsule endoscope 3 has traveled is obtained by the
following Expression.
Di={(Xi-1-Xi).sup.2+(Yi-1-Yi).sup.2+(Zi-1Zi).sup.2}.sup.1/2 (1)
[0041] When the distance Di that the capsule endoscope 3 travels is
small, there is a high possibility that images in the same field of
view may be captured. Accordingly, image-capture timing of the CCD
imager 17 in the capsule endoscope 3 is set to a low rate. For
example, in the case of capturing two frame images per second
(Ti=1/2[s]), the timing is changed to a rate at which one frame
image is captured per second (Ti=1/1[s]). Image-capture timing
Ti[s] can be calculated by the following Expression using the
distance Di.
Ti=.alpha./Di[s] (2)
where .alpha. is a constant.
[0042] In the signal processing circuit 35 of the external device
5, the CPU obtains the image-capture timing Ti[s]. The signal
processing circuit 35 supplies a signal indicating the obtained
image-capture timing to the transmitting and receiving circuit 33.
The transmitting and receiving circuit 33 transmits the signal to
the capsule endoscope 3 through the proper antenna 11ij (i.e.,
transmits the signal indicating the image-capture timing through
the above-described determined antenna most suitable to receive the
image signal).
[0043] In the capsule endoscope 3, the antenna 23 receives the
signal indicating the image-capture timing transmitted from the
antenna 11ij connected to the external device 5. The received
signal is supplied to the processing circuit 19 via the
communication processing circuit 20. The processing circuit 19
supplies a signal to control image capture to the CCD imager 17 in
response to the supplied signal indicating the image-capture
timing.
[0044] As for the constant .alpha. in Expression (2) to obtain the
image-capture timing, images and positional information sets of a
plurality of patients are collected and the constant .alpha. is
derived from distances of the capsule endoscope 3 between the
collected images. For instance, as shown in FIG. 7, images Pi-1 to
Pi+1 including the same subject are detected from the collected
images, the same subject being moved from the center to a
peripheral portion in the images. A distance D (=Di+Di+1) that the
capsule endoscope 3 has traveled in this case is obtained. When the
distance that the capsule endoscope 3 has traveled is larger than
the distance D, sections which are not captured as images may exist
between sections corresponding to the images. Therefore, a
coefficient for .alpha. is set so that at least one frame image is
captured in the distance D. The distance D may be obtained from the
average Davr of a plurality of samples.
Advantages
[0045] According to the present embodiment, the single-core coil
for generating a magnetic field is arranged in the capsule
endoscope 3 and the generated magnetic field is detected by the
plurality of coils disposed outside the body, so that the accurate
distance that the capsule endoscope 3 has traveled can be obtained.
Since the image-capture timing of the CCD imager 17 can be changed
on the basis of the accurate distance in the present embodiment, a
user can efficiently confirm a diagnosis using images.
Second Embodiment
[0046] FIG. 8 is a diagram explaining a process by a signal
processing circuit according to a second embodiment of the present
invention.
Structure
[0047] The structure of an apparatus according to the second
embodiment is identical to that according to the first embodiment
with the exception that a program, installed in a CPU of an
external device 5 in the second embodiment, for obtaining
image-capture timing Ti[s] differs from that of the first
embodiment.
Operation
[0048] According to the present embodiment, the image-capture
timing Ti[s] to be transmitted as a signal to a capsule endoscope 3
is derived from a predicted distance that the capsule endoscope 3
will travel.
[0049] Generally, a polynomial P(t) of degree n-1 is expressed as
follows.
P(t)=a0+a1t+a2t.sup.2+ . . . +an-1t.sup.n-1 (3)
[0050] When three estimated positions Pi-2, Pi-1, and Pi of the
capsule endoscope 3 are used, three coefficients a0, a1, and a2 in
Expression (3) are obtained. For example, the following three
equations with respect to the X direction are derived using
Expression (3).
Xi-2(t0)=aX0+aX1t0+aX2t0.sup.2
Xi-1(t1)=aX0+aX1t1+aX2t1.sup.2
Xi(t2)=aX0+aX1t2+aX2t2.sup.2 (4)
[0051] The coefficients with respect to the X direction can be
determined by solving the three simultaneous equations. Let t
denote time obtained from image-capture timing.
[0052] Coefficients with respect to the Y and Z directions are
similarly obtained, so that a predicted position P i+1 of the
capsule endoscope 3 shown in FIG. 8 can be calculated by the
following Expression (the predicted position P i+1 is a position
after time t3).
X i+1(t3)=aX0+aX1t3+aX2t3.sup.2
Y i+1(t3)=aY0+aY1t3+aY2t3.sup.2
Z i+1(t3)=aZ0+aZ1t3+aZ2t3.sup.2 (5)
[0053] The predicted position of the capsule endoscope 3 is
obtained using Expression (5). A predicted distance D i+1 shown in
FIG. 8 is calculated using Expression (1). Substituting the
calculated distance D i+1 into Expression (2) gives the
image-capture timing Ti[s].
[0054] The external device 5 transmits a signal indicating the
obtained image-capture timing to the capsule endoscope 3. The
capsule endoscope 3 generates a control signal for a CCD imager 17
to change the image-capture timing.
[0055] According to the present embodiment, the predicted position
of the capsule endoscope 3 is obtained using a second degree
polynomial. When a plurality of estimated positions of the capsule
endoscope 3 are used, the position of the capsule endoscope 3 can
be predicted more accurately. The position of the capsule endoscope
3 may be predicted using a spline function.
Advantages
[0056] In addition to the advantages of the first embodiment, the
position of the capsule endoscope 3 is predicted, whereby
image-capture timing at the predicted position can be accurately
set.
Third Embodiment
[0057] FIG. 9 is a diagram explaining a process by a signal
processing circuit according to a third embodiment of the present
invention.
Structure
[0058] The structure of an apparatus according to the third
embodiment is the same as that according to the first embodiment
with the exception that a CPU in an external device 5 executes a
process so as to control image-capture timing using information
regarding the estimated orientation of a capsule endoscope.
Operation
[0059] As described in the first embodiment, the position and
orientation of a capsule endoscope 3 can be estimated on the basis
of strength signals received through antennas 11ij. As shown in
FIG. 9, the orientation of the capsule endoscope 3 may not coincide
with the moving direction thereof. When a distance that the capsule
endoscope 3 has traveled is small and the orientation thereof is
greatly changed, captured images may be different from each other
in spite of the small distance.
[0060] The distance Di of the capsule endoscope 3 obtained in the
first embodiment is derived from a distance between positions
Pi=(Xi, Yi, Zi) and Pi-1=(Xi-1, Yi-1, Zi-1). Let Vi and Vi-1 denote
the orientations at the respective positions. A change
.DELTA..theta. in orientation is expressed as follows.
.DELTA..theta.=cos.sup.-1{ViVi-1/(|Vi|.times.|Vi-1|)} (6)
where the operation "" indicates the inner product of Vi and Vi-1
and |Vi| and |Vi-1| denote the magnitudes of vectors.
[0061] If the change .DELTA..theta. in orientation of the capsule
endoscope 3 is large, there is a lower likelihood that images in
the same field of view are captured. Accordingly, image-capture
timing of a CCD imager 17 in the capsule endoscope 3 is set to a
higher rate. Image-capture timing Ti[s] can be calculated using the
distance Di, the change .DELTA..theta. in orientation, in the
following Expression.
Ti=.alpha./Di+.beta..DELTA..theta..sup.[s] (7)
where .alpha. and .beta. are constants.
Advantages
[0062] In addition to the advantages of the first embodiment,
advantageously, even when the distance that the capsule endoscope
has traveled is small and the orientation thereof is drastically
changed, the proper image-capture timing can be set by detecting a
change in orientation.
Fourth Embodiment
[0063] FIG. 10 is a diagram showing the structure of a processing
circuit of a capsule endoscope 3 according to a fourth embodiment
of the present invention.
Structure
[0064] The structure of an apparatus according to the fourth
embodiment is identical to that according to the first embodiment
with the exception that a processing circuit 19 in the capsule
endoscope 3 includes a calculation function realized by, e.g., a
CPU 50 and a memory 51 as shown in FIG. 10.
Operation
[0065] Referring to FIG. 10, in the capsule endoscope 3, the
processing circuit 19 includes the calculation function realized by
the CPU 50 and the memory 51 and permits the capsule endoscope 3 to
execute a program therein. In the first embodiment, the program is
executed in the CPU and the memory included in the signal
processing circuit 35 of the external device 5.
[0066] The capsule endoscope 3 transmits an image signal and a
strength signal as shown in FIG. 5 at a predetermined radio-field
intensity through an antenna 23 through a communication processing
circuit 20. In an external device 5, a transmitting and receiving
circuit 33 receives the signals through each of antennas 11ax,
11aY, . . . , 11dY, and 11dZ of an antenna unit 4.
[0067] The transmitting and receiving circuit 33 supplies the image
signals and the strength signals to a signal processing circuit 35
to store the signals in memory means 47, such as a Compact Flash
(registered trademark) memory (CF memory) or a hard disk, connected
to the signal processing circuit 35. The signal processing circuit
35 supplies the strength signals received through the respective
antennas 11ij to the transmitting and receiving circuit 33. The
transmitting and receiving circuit 33 transmits the strength signal
to the capsule endoscope 3 through the proper one of the antenna
11ij. As described in the first embodiment, the antenna most
suitable to receive the image signal may be detected and, after
that, the strength signal may be transmitted.
[0068] The capsule endoscope 3 receives the strength signal
associated with the antenna 11ij transmitted from the external
device 5 through the antenna 23 and the communication processing
circuit 20 and supplies the received signal to the processing
circuit 19.
[0069] The program for estimating the position and orientation of
the capsule endoscope 3 using the strength signal received through
the antenna 11ij connected to the external device 5 is installed on
the CPU 50 and the memory 51 in the processing circuit 19 of the
capsule endoscope 3. As described in the first embodiment, the CPU
50 utilizes the method for solving a plurality of nonlinear
equations to estimate the position and orientation of the capsule
endoscope 3, thus obtaining image-capture timing of a CCD imager 17
on the basis of the estimated position and orientation. The CPU 50
transmits data regarding the obtained image-capture timing to the
processing circuit 19. The processing circuit 19 generates a
control signal to control image capture by the CCD imager 17, thus
controlling image capture by the CCD imager.
Advantages
[0070] In addition to the advantages of the first embodiment,
processes by the external device 5 can be distributed since a
distance that the capsule endoscope 3 travels can be calculated in
the capsule endoscope 3.
Fifth Embodiment
Structure
[0071] The structure of an apparatus according to a fifth
embodiment is the same as that according to the fourth embodiment
with the exception that an antenna 23 disposed in a capsule
endoscope 3 detects a magnetic field generated by an antenna 11ij
extracorporeally arranged.
Operation
[0072] A transmitting and receiving circuit 33 of an external
device 5 generates a signal to permit antennas 11ij to generate
magnetic fields having different frequencies. In response to the
generated signal, the antennas 11ij generate respective magnetic
fields having different frequencies. In the capsule endoscope 3,
the antenna 23 receives the generated magnetic fields. The antenna
23 receives a signal obtained by combining signals having different
strengths and frequencies. The received signal is subjected to
band-pass filtering and gain adjustment through a communication
processing circuit 20 and is then supplied to a processing circuit
19. The received signal supplied to the processing circuit 19 is
digitized and is then stored in a memory 51 connected to a CPU 50.
The CPU 50 performs frequency extraction (Fourier transform: FET)
on the received signal stored in the memory 51 to obtain signal
strengths corresponding to the magnetic fields generated by the
respective antennas 11ij.
[0073] A program for estimating the position and orientation of the
capsule endoscope 3 as described in the fourth embodiment is
installed on the capsule endoscope 3. Accordingly, the position and
orientation of the capsule endoscope 3 are estimated using signal
strengths corresponding to the respective antennas 11ij. A distance
is calculated using the estimated position and orientation, whereby
image-capture timing of a CCD imager 17 is obtained. Data regarding
the obtained image-capture timing is transmitted to the processing
circuit 19. The processing circuit 19 generates a control signal to
control image capture by the CCD imager 17, thus controlling image
capture by the CCD imager 17.
[0074] In the capsule endoscope 3, the communication processing
circuit 20 converts information regarding the position and
orientation obtained by the CPU 50 and a captured image signal into
a signal that can be transmitted from the antenna 23. The antenna
23 transmits the signal. The signal transmitted from the antenna 23
is supplied to the transmitting and receiving circuit 33 through
the antennas 11ij connected to the external device 5. A signal
processing circuit 35 converts the signal into a signal that can be
stored in memory means 47. The memory means 47 stores the
signal.
Advantages
[0075] In addition to the advantages of the fourth embodiment,
power consumption of button batteries 21 for supplying power can be
reduced since the antenna of the capsule endoscope 3 can detect
external magnetic fields.
Sixth Embodiment
[0076] FIG. 11 is a flowchart showing the flow of a process by a
signal processing circuit of an external device according to a
sixth embodiment of the present invention.
Structure
[0077] The structure of an apparatus according to the sixth
embodiment is the same as that according to the first embodiment
with the exception that recording of an image signal and
information regarding the position/orientation of a capsule
endoscope 3 on memory means 47 of an external device 5 is
controlled in accordance with a distance that the capsule endoscope
3 has traveled.
Operation
[0078] The capsule endoscope 3 transmits an image signal and a
strength signal as shown in FIG. 5 at a predetermined radio-field
intensity through an antenna 23. In the external device 5, a
transmitting and receiving circuit 33 receives the signals through
each of antennas 11ax, 11aY, . . . , 11dY, and 11dZ of an antenna
unit 4.
[0079] A signal processing circuit 35 of the external device 5
includes a CPU and a memory which are not shown. The image signal
and the strength signal, transmitted from the capsule endoscope 3
and received through each antenna 11ij, are recorded on the memory
means 47 in accordance with a program corresponding to the
flowchart shown in FIG. 11.
[0080] When the capsule endoscope 3 is inserted into a body, the
signal processing circuit 35 starts the program corresponding to
the flowchart shown in FIG. 11 from step S101. In step S102,
variables i, j, and jMAX are initialized such that i=0, j=1, and
jMAX=1.
[0081] In step S103, an image signal and a strength signal received
through any antenna 11ij are given to the program. If it is
determined in step S104 that the variable i is smaller than 0, the
image signal and the received signal strength are recorded on the
memory means 47 in step S105.
[0082] Subsequently, the process proceeds to step S106, in which it
is determined whether the capsule endoscope 3 is discharged from
the body. If the capsule endoscope 3 exists in the body, the
process proceeds to step S107, in which the variable i is
incremented. When the capsule endoscope 3 is discharged from the
body, the process proceeds to step S116, thus terminating the
program.
[0083] When the variable i is incremented in step S107, the process
proceeds to step S103, in which the next image signal and strength
signal are given to the program. If it is determined in step S104
that the variable i is larger than 0, the process proceeds to step
S108. 12 nonlinear equations, in which the position and orientation
of a single-core coil arranged in the capsule endoscope 3 are
unknown, are obtained using the signal strengths of the strength
signals received through the antennas 11ax, 11aY, . . . , 11dY, and
11dZ. The 12 nonlinear equations are solved by iterative
refinement, e.g., the Gauss-Newton method, whereby the position and
orientation of the capsule endoscope 3 are estimated.
[0084] Next, in step S109, a distance Di is calculated using
Expression (1). In step S110, recording timing Ti[s] is calculated
using Expression (2). If it is determined in step S111 that the
variable j is equal to the specific value jMAX, the process
proceeds to step S112, in which the image signal and strength
signal are recorded on the memory means 47. The process then
proceeds to step S113, in which an image recording interval is
obtained from the recording timing Ti[s].
[0085] For example, when 10 frame images are transmitted from the
capsule endoscope 3 for one second and the recording timing Ti is
calculated as 0.5 [s], one out of every five images is recorded
(jMAX is set to 5).
[0086] In step S114, the variable j is initialized. In step S106,
whether the capsule endoscope 3 exists in the body is
determined.
[0087] If it is determined in step S111 that the variable j is
different from the specific value jMAX, the process proceeds to
step S115, in which the variable j is incremented.
[0088] According to the present embodiment, the image recording
interval is obtained. Each image, which is not to be recorded, may
be recorded with information regarding the position and orientation
by compressing image data or reducing the size of the image or
converting the data into information, such as an icon. For example,
when the recording interval is set to five frames, four frame
images, which are not to be recorded, may be recorded on the memory
means 47 together with information regarding the position and
orientation such that the size of each image is reduced.
Advantages
[0089] In addition to the advantages of the first embodiment, a
distance that the capsule endoscope has traveled in the body is
obtained with accuracy and images are recorded. Advantageously, a
user can efficiently confirm a diagnosis using the images.
Seventh Embodiment
[0090] FIGS. 12 to 14 relate to a seventh embodiment of the present
invention. FIG. 12 is a flowchart showing the flow of a process by
a terminal. FIG. 13 is a first diagram showing an example of a
screen displayed on the terminal by the process of FIG. 12. FIG. 14
is a second diagram showing an example of a screen displayed on the
terminal by the process of FIG. 12.
Structure
[0091] Since the seventh embodiment is substantially identical to
the first embodiment, only the difference therebetween will now be
described. The same components are designated by the same reference
numerals and a description of the previously described components
is omitted.
Operation
[0092] As shown in FIG. 4, a capsule endoscope 3 transmits an image
signal and a strength signal as shown in FIG. 5 at a predetermined
radio-field intensity through an antenna 23. In an external device
5, a transmitting and receiving circuit 33 receives the signals
through each of antennas 11ax, 11aY, . . . , 11dY, and 11dZ of an
antenna unit 4.
[0093] The transmitting and receiving circuit 33 supplies the image
signals and strength signals to a signal processing circuit 35. The
signal processing circuit 35 compares strength levels of the
strength signals received through the respective antennas 11ij.
Consequently, the signal processing circuit 35 detects the antenna
most suitable to receive the image signal transmitted from the
capsule endoscope 3. The signal processing circuit 35 supplies the
image signal obtained through the most suitable antenna and the
strength signals received through the respective antennas 11ij to
memory means 47, such as a Compact Flash (registered trademark)
memory (CF memory) or a hard disk, connected to the signal
processing circuit 35 to store the signals.
[0094] When observation in a body through the capsule endoscope 3
is finished, the image signals and strength signals recorded on the
memory means 47 of the external device 5 are transferred to
recording means in a terminal 7.
[0095] The terminal 7 includes a CPU and a memory, which are not
shown, whereby application software for displaying images is
executed through a user interface, such as a keyboard or a mouse,
connected to the terminal 7.
[0096] When the application software is executed, in the terminal
7, a program corresponding to the flowchart shown in FIG. 12 starts
from step S201. In step S202, variables i, j, and jMAX are
initialized such that i=0, j=1, and jMAX=1. In step S203, an image
signal and a strength signal of any antenna 11ij are read from the
recording means and are then given to the program. If it is
determined in step S204 that the variable i is smaller than 0, the
image signal is displayed on display means, such as a monitor, in
step S205.
[0097] Next, the process proceeds to step S206, in which it is
determined whether all of the image signals and strength signals
have already been read out. If any unread image and strength
signals exist, the process proceeds to step S207, in which the
variable i is incremented. When all of the image and strength
signals have already been read, the process proceeds to step S216,
thus terminating the program.
[0098] When the variable i is incremented in step S207, the process
proceeds to step S203, in which the next image signal and strength
signal are read out from the recording means and are then given to
the program. If it is determined in step S204 that the variable i
is larger than 0, the process proceeds to step S208. 12 nonlinear
equations, in which the position and orientation of a single-core
coil arranged in the capsule endoscope 3 are unknown, are obtained
using strength levels of the strength signals received through the
antennas 11ax, 11aY, . . . , 11dY, and 11dZ. The 12 nonlinear
equations are solved by iterative refinement, e.g., the
Gauss-Newton method, thus estimating the position and orientation
of the capsule endoscope 3.
[0099] Thereafter, in step S209, a distance Di is calculated using
Expression (1). In step S210, display timing Ti[s] is calculated
using Expression (2). If it is determined in step S211 that the
variable j is equal to the specific value jMAX, the process
proceeds to step S212, in which the corresponding image is
displayed on the display means, such as a monitor. The process then
proceeds to step S213, in which an image display interval is
obtained on the basis of the display timing Ti[s].
[0100] For example, when 10 frame images are recorded on the
recording means for one second and the display timing Ti is
calculated as 0.5 [s], one out of every five images is displayed
(jMAX is set to 5).
[0101] In step S214, the variable j is initialized. In step S206,
it is determined whether all of the image signals and strength
signals have already been read.
[0102] According to the present embodiment, an image may not be
displayed as a moving picture depending on display timing. In this
case, as shown in FIG. 13, an image, which is not displayed as a
moving picture, may be displayed in an area 101 separated from a
moving picture display area 100. Alternatively, as shown in FIG.
14, images may be reduced or be displayed in a different form,
e.g., as icons.
Advantages
[0103] According to the present embodiment, a distance that the
capsule endoscope 3 has traveled is obtained with accuracy and
images are displayed. Advantageously, a user can efficiently
confirm a diagnosis using the images.
[0104] In the present invention, it will be apparent that a wide
range of different embodiments can be formed based on this
invention without departing from the spirit and scope of this
invention. The present invention will be restricted by the appended
claims but not be limited to any particular embodiment.
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