Bendable portion of endoscope

摘要

A bendable portion for an endoscope includes a bending mechanism which minimizes the bendable portion diameter and allows a large degree of bending. A first bending mechanism embodiment uses fluid pressure in an axially oriented chamber in a elastic body of the bendable portion. Expansion restraining members are used to restrict the expansion of the bendable portion to only the axial direction, and to protect internal members in the bendable portion. A second bending mechanism embodiment uses a shape memory alloy coil encircling the elastic body of the bendable portion. The shape memory alloy coil is heated to define the shape of the bendable portion.