Capsule endoscope

#The present invention relates to a capsule endoscope that is swallowed by a patient and used for imaging the inside of a body cavity.

#In the medical field, a capsule endoscope in which an image sensor is stored in a capsule is now used for a diagnosis, in addition to an insertion-type endoscope having the image sensor provided at a distal end of a long insert section.

#The capsule endoscope has a hollow capsule body, a dome-shaped transparent cover attached to one end of the capsule body, and an imaging lens that forms an image from light entered through the transparent cover on an image sensor. The capsule endoscope is formed in such a size that the patient can easily swallow (see Patent Documents 1 to 3). Owing to this, the capsule endoscope eliminates burden on a patient occurred in the diagnosis using the insertion-type endoscope, such as swallowing the insert section of the endoscope into his/her mouth or being kept inserting the insert section through the body for long periods of time.

#FIG. 1 is a cross-sectional view illustrating a capsule endoscope of the present invention.

#FIG. 2 is a cross-sectional view illustrating the capsule endoscope of the present invention viewed from a direction which is rotated 90 degrees clockwise from FIG. 1.

#FIG. 3 is a cross-sectional view of the capsule endoscope of the present invention used for explaining mathematical expression 1 to mathematical expression 3.

#As shown in FIG. 1, a capsule endoscope 10 is formed in such a size that it can be swallowed by a patient with ease, and captures images inside the stomach or intestines during the period from being swallowed until excretion from the body at constant time intervals. In this embodiment, a subject 12 of concave sphere is explained as a subject to be captured with the capsule endoscope 10. Note that the shape of the subject is not limited to the concave sphere but may be in other concave curved forms.

#As shown in FIG. 1 and FIG. 2 illustrating the capsule endoscope 10 viewed from a direction which is rotated 90 degrees clockwise from FIG. 1, the capsule endoscope 10 is provided with a capsule 13, an image sensor 14, an imaging lens 20, and a cover glass 21. The capsule 13 has a capsule body 22 and a transparent cover 23. The capsule body 22 is formed hollow, and has an opening 22b at its end 22a. The imaging lens 20 is provided such that a part thereof is positioned inside the capsule body 22 and the rest is protruded from the opening 22b. The transparent cover 23 is formed into a dome shape, and is attached to the end 22a of the capsule body 22 to cover the imaging lens 20 protruded from the opening 22b. Depending on the design conditions of the lens, the whole imaging lens may be protruded from the opening of the capsule body, or the whole imaging lens may be provided inside the capsule body.

#The imaging lens 20 and transparent cover 23 have optical power for forming an image from light from the subject 12 on the image sensor 14. On the other hand, the cover glass 21 transmits the light from the subject 12 without refracting it, which means has no optical power like the imaging lens 20 and transparent cover 23. The material of the transparent cover 23 may be the same as the imaging lens 20 and not particularly limited.