Endoscope

Claim 1

An endoscope comprising: (i) an elongated insertion section having a distal end and a proximal end, said insertion section being adapted to be inserted in a coelic cavity; (ii) a control section connected to the proximal end of said insertion section; (iii) a suction channel member having first and second ends disposed in said insertion section, the first end of said suction channel member being open to the distal end of said insertion section, and the second end of said suction channel member being connected to said control section; (iv) a suction tube having first and second ends, the first end of said suction tube being positioned in said control section;and (v) a suction selector mechanism disposed in said control section, which allows connection of the second end of said suction channel member with the first end of said suction tube, and which selectively connects said suction channel member and said suction tube, said suction selector mechanism including : (a) a cylinder having an inner surface portion a cross-section of which has a circular shape, (b) a piston having an outer surface disposed inside said cylinder and, as part of the outer surface, a circular outer surface portion being provided such that it is brought into air-tight and slidable contact with the inner surface portion of said cylinder, said piston being capable of adopting a non-pressed position and a pressed position and of moving therebetween, (c) regulating means for regulating movement of said piston between the non-pressed position and the pressed position, (d) urging means for urging said piston into the non-pressed position, (e) an end portion which is formed as a unit with said piston and extends therefrom toward said regulating means, (f) a first connecting port which is formed in the inner surface portion of said cylinder and which connects with the second end of said suction channel member, said first connecting port being closed by the circular outer surface portion of said piston when said piston is positioned in the non-pressed position, and being freed of the circular outer surface portion of said piston when said piston is positioned in the pressed portion, (g) a small-diameter portion which is formed along the outer surface of said piston and which defines a space with the inner surface portion of said cylinder, said small-diameter portion being positioned opposing said first connecting port when said piston is in the pressed position, (h) a second connecting port disposed in said cylinder and connected to the first end of said suction tube, said second connecting port being positioned outside a range of movement of the circular outer surface portion of said piston, (i) communicating means, formed in said piston, for communicating the space defined by said small-diameter portion with said second connecting port, said end portion of said piston having a leakage hole of a certain diameter communcating with the outside of said control section, said piston having said communicating means and a hollow chamber which communicates with said leakage hole, said hollow chamber having a diameter greater than the diameter of said leakage hole, the outer surface of said small-diameter portion being tapered from said leakage hole towards said hollow chamber and having a hole continuously open to said hollow chamber.