Capsule type endoscope
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Abstract
A capsule type endoscope includes an illumination device, an imaging device, and a transparent cover covering the illumination device and the imaging device. The imaging device has an objective optical system and an image sensor. When the objective optical system satisfies Condition (1) described below and a white cylinder with a reflectance of 90%, satisfying Condition (3) described below, is observed, illuminance of the imaging surface of the image sensor satisfies Condition (2) described below, in a state where a longitudinal center axis of a capsule coincides with the center axis of the white cylinder with a reflectance of 90%.
ω≧50° (1)
T1×0.5≦T2 (2)
D=1.2×Φ (3)
where ω is a half of a field angle of the objective optical system, T1 is the maximum illuminance in an area on the imaging surface of the image sensor corresponding to a field region of the objective optical system, T2 is illuminance at a position on the imaging surface of the image sensor corresponding to a half of the maximum image height of the objective optical system, D is the inside diameter of the white cylinder, and Φ is the outside diameter of the capsule type endoscope.
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Citations
10 Claims
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1-5. -5. (canceled)
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6. A capsule type endoscope comprising:
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illumination means for illuminating an object;
imaging means for imaging the object; and
a transparent cover for covering the illumination means and imaging means, wherein the imaging means includes an objective optical system and an image sensor, and when the objective optical system satisfies Condition (1) described below, an illumination distribution of a surface of a spherical object placed ahead of the objective optical system satisfies Condition (4) described below;
ω
≧
50°
(1)
R(θ
)≦
R(O)×
cos2(θ
)
(4)
where ω
is a half of a field angle of the objective optical system, R(θ
) is illuminance of an object surface relative to a field angle θ
°
of the objective optical system, and R(O) is illuminance of the object surface crossing an optical axis of the objective optical system.
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7. (canceled)
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8. A capsule endoscope having an observation apparatus, the capsule type endoscope comprising:
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illumination means for illuminating an object;
imaging means for imaging the object;
a transparent cover for covering the illumination means and the imaging means; and
means for radio-transmitting an imaging signal from the imaging means, the observation apparatus comprising;
receiving means for receiving the imaging signal;
an image processing circuit defining an image in accordance with the imaging signal from the receiving means; and
an image display device displaying an image signal from the image processing circuit as an image, wherein the imaging means includes an objective optical system and an image sensor, and when the objective optical system satisfies Condition (1) described below and a center axis of a white cylinder having an inner wall with a preset reflectance relative to white light and satisfying Condition (6) described below is made to coincide with a longitudinal center axis of the capsule type endoscope to observe the inner wall of the white cylinder, an intensity distribution of image signals ranging from a center of the image displayed on the image display device to a periphery satisfies Condition (5) described below;
ω
≧
50°
(1)
T3×
0.5≦
T4
(5)
(0.025×
α
)1/4×
Φ
=D
(6)where ω
is a half of a field angle of the objective optical system, T3 is a maximum value of an intensity of an image signal measured in the range from the center of the image to the periphery, T4 is a value of the intensity of the image signal corresponding to a half of a field angle of the objective optical system, α
is the reflectance (%) of the inner wall of the white cylinder, D is an inside diameter (mm) of the white cylinder, and Φ
is an outside diameter (mm) of the capsule type endoscope.
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9. A capsule type endoscope comprising:
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illumination means for illuminating an object;
imaging means for imaging the object; and
a transparent cover for covering the illumination means and the imaging means, wherein the imaging means includes an objective optical system and an image sensor, and when the objective optical system satisfies Condition (1) described below and a white cylinder having an inner wall with a preset reflectance relative to white light and satisfying Condition (6) described below is observed, illuminance of an imaging surface of the image sensor in a state where a longitudinal center axis of the capsule type endoscope coincides with a center axis of the white cylinder satisfies Condition (2) described below;
ω
≧
50°
(1)
T1×
0.5≦
T2
(2)
(0.025×
α
)1/4×
Φ
=D
(6)where ω
is a half of a field angle of the objective optical system, T1 is a maximum illuminance in an area on the imaging surface of the image sensor corresponding to a field region of the objective optical system, T2 is illuminance at a position on the imaging surface of the image sensor corresponding to a half a maximum image height of the objective optical system, α
is the reflectance (%) of the inner wall of the white cylinder, D is an inside diameter (mm) of the white cylinder, and Φ
is an outside diameter (mm) of the capsule type endoscope.
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10. A method of examining a capsule type endoscope, comprising the steps of:
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making a center axis of a cylinder having an inner wall with a preset reflectance relative to white light and satisfying Condition (6) described below coincide with a longitudinal center axis of the capsule type endoscope;
(0.025×
α
)1/4×
Φ
=D
(6)where α
is the reflectance (%) of the inner wall of the white cylinder, D is an inside diameter (mm) of the white cylinder, and Φ
is an outside diameter (mm) of the capsule type endoscope;
illuminating the inner wall of the cylinder by illumination means of the capsule type endoscope to image the inner wall of the cylinder by imaging means;
displaying an image formed by the capsule type endoscope on a display device; and
measuring an intensity distribution of image signals ranging from a center of the image to a periphery.
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Specification