Endoscope

Claim 1

An endoscope comprising: (a) an elongate insertion section (3) having distal and proximal ends (5, 10) and adapted to be inserted into a body cavity; (b) a control section (2) connected to the proximal end (10) of the insertion section. (3); (c) fluid guide means comprised of an air guide tube section (8) and water guide tube section (9), having one end opened'at the distal end (5) and the other end extending into the control section (2), and extending through the insertion section (3); (d) an air supply tube (12) provided to the control section (2) for flowing an air; (e) a water supply tube (13) provided to the control section (2) for permitting the supply of water; and (f) air-supply and water-supply changeover means for permitting the air supply tube (12) to be connected to the air guide tube section (8) or the water supply tube (13) to be connected to the water guide section (9) of the fluid guide means, characterized in that said air-supply and water-supply changeover means comprising: (i) cylinder means (15) where one end of the air guide tube section (8) are disposed away from one end of the air supply tube (12) to permit a fluid communication to be made therebetween; (ii) piston means (16) slidably inserted into the cylinder means (15) to permit switching. to air supply and water supply to be effected between a ready position and an operative position; (iii) means for urging the piston means (16) into the ready position; and (iv) a non-return valve member (35) provided within the cylinder means (15) such that it is located between said one end of the air supply tube (12) and said one end of the air guide tube section (8) of the fluid guide means, said device, together with the piston means (16), being slidably movable, as a unit, relative to the cylinder means (15) according to the movement of the piston means (16) to prevent the backflow of a fluid from the air guide section (8), while permitting a flow of the liquid from the air supply tube (12) through the valve member (35).