Endoscope with angled inflation channel

1. An endoscope apparatus comprising:

an endoscope comprising an insertion portion, wherein an air hole is formed at a distal end of the insertion portion so as to pass through a distal end hard portion of the insertion portion; and

a balloon attached to the distal end of the insertion portion, the balloon being expanded by supply of air through an inlet/outlet port of the air hole and contracted by suction of air through of the inlet/outlet port,

wherein the inlet/outlet port of the air hole is formed to be inclined at a predetermined angle to an axis of the insertion portion of the endoscope, and is connected to an air tube disposed in the endoscope insertion portion via a piping member,

wherein the inlet/outlet port of the air hole is formed into a slot by cutting a thickness section of the distal end hard portion located upward of one-end opening portion of the piping member,

wherein the slot of the inlet/outlet port of air hole has

(i) a surface opening portion which appears on a surface of the distal end hard portion,

wherein the surface opening portion is larger in dimension than the piping member, and a length in a longitude direction of the surface opening portion is longer than a diameter of the piping member, and

wherein the surface opening portion is formed on the surface of the distal end hard portion, heights of the surface opening portion edges are substantially equal back and forth in the longitude direction of the insertion portion, and the air hole is formed on an inside of a position of a diameter of the distal end hard portion, and

(ii) a vertical end face in the vertical direction with respect to the axial center of the insertion portion, and

wherein the piping member is disposed in the distal end hard portion and is formed by bending at a predetermined radius of curvature ratio so as to smoothly insert a cleansing brush into the piping member.

2. The endoscope apparatus according to claim 1 ,

wherein the piping member is formed so as to satisfy the conditions of r>5 mm, θ<60°, and h<d/2 where a radius of curvature of the piping member is r, an attaching angle of the piping member is θ, height of the piping member from an outer surface of the distal end of the insertion portion is h after the piping member is attached, and an outer diameter of the distal end of the insertion portion is d.

3. The endoscope apparatus according to claim 2 , wherein the inlet/outlet port is formed to be inclined forward at said predetermined angle θ with respect to an axial center of the insertion portion.