Method for affixing endoscope curved section protective sheath

1. An endoscope comprising:

an attachment section having at least first and second sections extending in an axial direction from a rear end of said attachment section, wherein said attachment section is in the form of a pipe;

a tubular curved section protective sheath having an end that covers an outer periphery of said first section, which extends from said rear end of said attachment section, so as to cover an endoscope curved section while leaving an outer periphery of said second section uncovered;

a filamentous member wound around the outer periphery of said end of said tubular curved section protective sheath thereby affixing said end of said tubular curved section protective sheath to said first section of said attachment section;

an adhesive agent layered on the outer periphery of at least said end of said tubular curved section protective sheath so as to cover said filamentous member; and

a ring member fitted to the outer periphery of said end of said tubular curved section protective sheath so as to cover said adhesive agent, and an inner peripheral surface of said ring member being bonded to said filamentous member with said adhesive agent, wherein

said ring member includes a small-diameter ring section having an inner diameter and a large-diameter ring section having an inner diameter, wherein said inner diameter of said large-diameter ring section is larger than said inner diameter of said small-diameter ring section,

said large-diameter ring section is arranged surrounding said end of said tubular curved section protective sheath so as to cover said filamentous member, and

said small-diameter ring section covers said second section and is directly bonded to said second section through said adhesive agent.

2. The endoscope according to claim 1 , wherein said second section is a large-diameter section having an outer diameter and said first section is a small-diameter section having an outer diameter, wherein said outer diameter of said small-diameter section is smaller than said outer diameter of said large-diameter section.

3. The endoscope according to claim 2 , wherein

said attachment section is further provided, closer in the axial direction to said rear end of said attachment section than said smaller-diameter section, with an enlarged-diameter section that has a larger outer diameter than said outer diameter of said small-diameter section, forming a concave part on the outer peripheral side of said small-diameter section, and

said end of said tubular curved section protective sheath is arranged in said concave part.

4. The endoscope according to claim 1 , wherein a separating distance between said filamentous member and the inner peripheral surface of said ring member is larger than a distance between the outer peripheral surface of said second section and the inner peripheral surface of said ring member.

5. The endoscope according to claim 4 , wherein the separating distance between said filamentous member and the inner peripheral surface of said ring member is less than 0.05 mm.

6. The endoscope according to claim 1 , wherein

said curved section protective sheath has a step section arranged in the vicinity of said end of said tubular curved section protective sheath which is reduced in diameter due to constriction with said filamentous member, said step section having an outer diameter that is gradually tapered, and

said ring member has one end arranged so as to abut against the step section.

7. The endoscope according to claim 6 , wherein the adhesive agent layered on the outer periphery of said end of said tubular curved section protective sheath is arranged so as to protrude between one end of said ring member and said step section to bond said end of said ring member to said step section.

8. The endoscope according to claim 1 , wherein a surface of said ring member that is in contact with said adhesive agent, at least in part, is either rough-surfaced or provided with irregularities.

9. The endoscope according to claim 1 , wherein said attachment section is a connection pipe that connects an endoscope front end to said endoscope curved section.

10. The endoscope according to claim 1 , wherein the inner peripheral surface of said small-diameter ring section is provided along the outer peripheral surface of said second section.

11. The endoscope according to claim 1 , wherein the outer peripheral surface of said small-diameter ring section is tapered.

12. The endoscope according to claim 1 , wherein the adhesive agent layered on the outer periphery of said end of said tubular curved section protective sheath is arranged so as to protrude between said small-diameter ring section and said second section to bond said small-diameter ring section to said second section.

13. The endoscope according to claim 1 , wherein said first and second sections are continuous with each other.

14. A method of manufacturing an endoscope, comprising:

providing an end of a tubular curved section protective sheath for covering an endoscope curved section and to cover the outer periphery of an attachment section, said attachment section having at least first and second sections extending in an axial direction from a rear end of said attachment section, wherein said attachment section is provided in the form of a pipe;

winding a filamentous member around the outer periphery of said end of said tubular curved section protective sheath thereby affixing said end of said tubular curved section protective sheath to said first section of said attachment section;

layering an adhesive agent on at least the outer periphery of said end of said tubular curved section protective sheath so as to cover said filamentous member; and

fitting a ring member to the outer periphery of said end of said tubular curved section protective sheath so as to cover said adhesive agent thereby bonding the inner peripheral surface of said ring member to said filamentous member with said adhesive agent, wherein

said ring member includes a small-diameter ring section having an inner diameter and a large-diameter ring section having an inner diameter, wherein said inner diameter of the large-diameter ring section is larger than said inner diameter of said small-diameter ring section,

said large-diameter ring section is arranged surrounding said end of said tubular curved section protective sheath so as to cover said filamentous member, and

said small-diameter ring section covers said second section and is directly bonded to said second section through said adhesive agent.