Endoscope having attachable/detachable raise base

1. An endoscope adapted to insert a treatment tool, the endoscope comprising:

an opening from which the treatment tool protrudes, the opening being provided on a distal end of the endoscope;

a rotary shaft rotatably mounted in the opening, a direction of a shaft center of the rotary shaft being perpendicular to a longitudinal direction of the endo scope; and

a raise base that is attachable to the rotary shaft and detachable from the rotary shaft in a predetermined attaching/detaching direction through the opening, the raise base being configured to rise around the rotary shaft while being attached to the rotary shaft, wherein

the raise base includes a pair of engagement sections made of an elastic material, the pair of engagement sections extending in the attaching/detaching direction and opposing to each other with the rotary shaft interposed therebetween,

the rotary shaft includes an engagement surface extending in the attaching/detaching direction and abutting an inner surface of the engagement section, and

one of the pair of engagement sections and the rotary shaft further comprising a projection configured to project toward a direction intersecting with the attaching/detaching direction.

2. The endoscope according to claim 1 , further comprising:

an operating unit configured to receive an operation for rotating the rotary shaft; and

a wire provided along the longitudinal direction, the wire having a proximal end connected to the operation unit, the wire having a distal end connected to the rotary shaft,

wherein the rotary shaft includes a shaft section that is perpendicular to the longitudinal direction, and a wire connection section connected to the distal end of the wire, and

the operating unit raises the treatment tool by raising the raise base by rotating the shaft section of the rotary shaft by using the wire in accordance with the operation.

3. The endoscope according to claim 1 , wherein

the projection is provided on distal ends of the respective engagement sections to protrude from the engagement sections toward the rotary shaft.

4. The endoscope according to claim 3 , wherein a longitudinal direction of the raise base is identical to a direction in which the engagement section extends.

5. The endoscope according to claim 1 , wherein

the raise base includes

a recessed portion provided on an inner side with respect to a direction in which the engagement sections are opposed to each other, and

the projection is a convex portion protruding from the engagement surface toward the engagement section to be engaged with the recessed portion of the raise base.

6. The endoscope according to claim 1 , wherein the raise base includes an attaching/detaching-direction display marker configured to indicate the attaching/detaching direction.

7. The endoscope according to claim 1 , further comprising a rotation preventing unit configured to prevent the raise base and the rotary shaft from relatively rotating.

8. The endoscope according to claim 7 , wherein the rotation preventing unit includes

a groove formed on one of the raise base and the rotary shaft; and

a projection formed on an other of the raise base and the rotary shaft.

9. The endoscope according to claim 1 , wherein the endoscope is an ultrasound endoscope that further includes an ultrasound transducer provided on a distal end.

10. The endoscope according to claim 1 , further comprising an elastic member provided around the rotary shaft in a middle of an axial direction of the rotary shaft such that the elastic member contacts a circumference surface of the rotary shaft.