The present disclosure relates to subject matter contained in Japanese patent application No. 3-266240 (filed on Oct. 15, 1991), which is expressly incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a bendable portion which is provided at the distal end of an insert part of an endoscope and bent by remote control.
2. Description of the Prior Art
To sterilize or disinfect an endoscope by using ethylene oxide gas or by autoclaving, it is necessary to raise and reduce the pressure in the tank containing the endoscope. Accordingly, the endoscope must be designed to withstand such a pressure change.
The most serious problem that is associated with autoclaving is that a bendable portion covering tube, that is the most flexible of the sheathing members of the endoscope, is inflated and likely to rupture when the pressure in the tank is reduced.
It has been conventional practice to provide a bellows which inflates when the ambient pressure is reduced, or to provide a valve or other similar device in the control part or the light guide connector of the endoscope so as to keep the inside of the endoscope at the same pressure as the ambient pressure, thereby preventing the bendable portion covering tube from rupturing when the pressure in the tank is reduced.
However, the addition of a bellows or a valve device increases the cost of the apparatus. In addition, since the bendable portion covering structure itself is not changed, if the function of the bellows or the valve cannot satisfactorily comply with the reduced pressure conditions, the bendable portion covering tube may rupture.