Endoscope

Claim 1

An endoscope adapted for insertion into a substantially Ushaped passage of a bronchus of a human body comprising in combination: an elongated flexible distal end portion having forward and rearward ends and housing an image forming optical system; a proximal end portion including a control housing; an intermediate portion connecting said distal end portion and said proximal end portion; said intermediate portion including a controllably bendable elongated tube and a yieldably flexible elongated tube, said controllably bendable tube and said yieldably flexible tube having respective forward and rearward ends; the forward end of said controllably bendable tube connected to said distal end portion and the rearward end thereof to said yieldably flexible tube; the forward end of said yieldably flexible tube connected to aid controllably bendable tube and the rearward end thereof to said control housing; said controllably bendable tube including a first bendable tube section and a second bendable tube section connected together, said first and second tube sections having respective forward and rearward ends, the forward end of said first bendable tube section connected to the rearward end of said distal end portion and the rearward end of said second bendable tube section connected to the forward end of said yieldably flexible tube; said first bendable tube section including a plurality of annular ring members arranged in series lengthwise thereof and pivotably connected to each other at the diametrically opposite positions in the respective edges of each of said annular ring members so as to provide sufficient pliability thereof; said second bendable tube section including a helically wound thin strip member; said helically wound thin strip member structurally providing less pliability than said annular ring members; the entire length of said yieldably flexible tube includes an additional helically wound thin strip member wound in the helical direction opposite to that of said helically wound thin strip member of said bendable tube section, said additional helically wound thin strip member providing a small pliability; thereby the respective degrees of pliability of said distal end portion, said controllably bendable tube, and said yieldably bendable tube permitting the insertion of the respective pliable elements in said substantially U-shaped passage of the bronchus; an image transmitting optical system extending through said controllably bendable tube and said yieldably flexible tube, said image transmitting optical system having forward and rearward ends, the forward end of said image transmitting optical system operatively located behind and adjacent said image forming optical system and the rearward end thereof terminatiNg in said control housing thereby permitting an image of an object operatively formed by said image forming optical system on the forward end of said image transmitting optical system and being transmitted therethrough to the rearward end thereof to be viewed in said proximal end portion; said controllably bendable le tube being operatively controllably bent by string means secured at the forward end thereof to the rearward end of said distal end portion and extending through said controllably bendable tube and said yieldably flexible tube to said control housing so as to be connected at the rearward end thereof to said control housing; said string means being slidably mounted in substantially noncontractable coil members attached to the interior of said controllably bendable tube and terminating with the forward end thereof at the forward end of said second bendable tube section while the rearward end thereof is secured to said control housing, the length of said non-contractable coil members extending through said yieldably flexible tube together with said string means and unattached thereto thereby permitting said controllably bendable tube to be bent exactly in response to the actuation of said string means by said manipulating means while said yieldably flexible tube is freely bent following the curvature of the passage through which said distal end portion is inserted without any interferene with the operation of said string means; and means provided in said control housing and connected to said string means to manipulate said distal end portion to the extremity of said substantially U-shaped passage of the bronchus.