Lens barrel having a linear guide mechanism

A lens barrel comprising:

• an outer barrel, an inner periphery of said outer barrel being provided with a first thread and a plurality of linear guide grooves each intersecting said first thread, said plurality of linear guide grooves extending in a direction of an optical axis of said lens barrel;
• a middle barrel, an outer periphery of said middle barrel being provided with a second thread meshing with said first thread so that said middle barrel is movable along said optical axis while rotating about said optical axis with respect to said outer barrel;
• an inner barrel positioned inside said middle barrel and moved together with said inner barrel along said optical axis, a rear end of said inner barrel including a plurality of followers which respectively engage with said plurality of linear guide grooves so that inner barrel is guided along said optical axis without rotating about said optical axis with respect to said outer barrel;
• a plurality of recesses each formed at a front end of a corresponding one of said plurality of linear guide grooves on said inner periphery of said outer barrel, said plurality of recesses each having a width greater than said corresponding one of said plurality of linear guide grooves;
• and
• an annular retaining member for preventing said middle barrel from disengaging from said outer barrel, said annular retaining member being provided with a plurality of engaging projections each extending in said direction of said optical axis to engage with a corresponding one of said plurality of recesses, said annular retaining member being secured to a front end of said outer barrel after said middle barrel has been engaged with said outer barrel and said plurality of engaging projections have respectively engaged with said plurality of linear guide grooves.

A lens barrel comprising:

• an outer barrel provided on an inner periphery with a first thread;
• a middle barrel provided on an outer periphery with a second thread meshing with said first thread of said outer barrel;
• an inner barrel positioned inside said middle barrel and provided with at least one follower;
• an annular retaining member secured to a front end of said outer barrel which prevents said middle barrel from disengaging from said outer barrel;
• at least one linear guide groove which extends in a direction of an optical axis of said lens barrel and with which said at least one follower engages, wherein a portion of said at least one linear guide groove is formed on said annular retaining member and a remaining portion of said at least one linear guide groove is formed on an inner periphery of said outer barrel.

A lens barrel comprising:

• an outer barrel provided on an inner periphery with a first thread and a linear guide groove intersecting said first thread and extending in a direction of an optical axis of said lens barrel;
• a middle barrel provided on an outer periphery with a second thread meshing with said first thread;
• an inner barrel positioned inside said middle barrel and provided with a follower which engages with said linear guide groove to be guided along said linear guide groove, said middle barrel being movable along said optical axis together with said inner barrel such that a distance between said middle and said inner barrels remains constant while said middle barrel rotates about said optical axis relative to said inner barrel;
• and
• at least one projection formed at a bottom of said linear guide groove, said at least one projection engaging with said second thread so as to function as a part of said first thread.