Endoscope having flexible tube

An endoscope having an elongated tube for entry in a body cavity and imaging of an object, comprising:

• a flexible tube structure for constituting said elongated tube, wherein bending stiffness of said flexible tube structure is different in an axial direction;
• a coil spring, contained in said flexible tube structure to extend in said axial direction, for constituting a variable stiffness device;
• a wire disposed to extend in said axial direction, received through said coil spring, a distal end of said coil spring being retained on said wire, for constituting said variable stiffness device;
• an internal structure contained in said flexible tube structure;
• an externally operable stiffness controller for changing coil tightness of said coil spring by use of said wire, to adjust said bending stiffness of said elongated tube;
• wherein in case said bending stiffness is changed in one radial direction at an equal point with reference to said axial direction, a difference between maximum and minimum levels of bending stiffness of said variable stiffness device is at most 0.2 time as much as minimum bending stiffness of said flexible tube structure inclusive of said internal structure other than said variable stiffness device in said axial direction upon occurrence of undulating motion of said coil spring in response to compression force of said stiffness controller to said coil spring.

An endoscope having an elongated tube for entry in a body cavity and imaging of an object, comprising:

• a flexible tube structure for constituting said elongated tube;
• a coil spring, contained in said flexible tube structure to extend in an axial direction, for constituting a variable stiffness device;
• a wire disposed to extend in said axial direction, received through said coil spring, a distal end of said coil spring being retained on said wire, for constituting said variable stiffness device;
• an easily bendable portion formed with at least one of said coil spring and said wire;
• an externally operable stiffness controller for changing coil tightness of said coil spring by use of said wire, to adjust bending stiffness of said elongated tube.