Patent ID: 6654555
Filing Date: 2003-11-25
Classification: G03B

Abstract:
An engagement structure for cylindrical members comprising:a first cylindrical member including a plurality of engagement projection portions of different shapes having the same projecting length in the radial direction, each of said plurality of engagement projection portions having at least one projection, wherein at least one of said plurality of engagement projection portions includes at least one groove; and a second cylindrical member including a plurality of groove portions corresponding to the engagement projection portions, each said plurality of groove portions having at least one groove, wherein at least one of said plurality of groove portions includes at least one projection; wherein one of said first and second cylindrical members is accommodated inside the other of said first and second cylindrical members; the engagement projection portions and the corresponding groove portions can be engaged and disengaged only at one relative circumferential position of said first and second cylindrical members; and at a relative circumferential position other than said one relative circumferential position of said first and second cylindrical members, the engagement projection portions of said first cylindrical member are always engaged with at least a portion of the groove portions other than the grooves thereof.