| 摘要 |
PURPOSE: A rotary forward or backward structure of a lens barrel is provided to enable a sure to make a compact gear speed reduction mechanism. CONSTITUTION: A rotary ring(11) is supported by a fixed ring(22) and rotates and moves in an optical axial direction. The rotary ring includes a cylindrical face gear on the rear end of the optical axial direction. A rotary ring drive gear(28) is rotated by a motor. The rotary ring drive gear includes a long gear(28a) and a gear(28b) with a large diameter. The long gear is long formed in the optical axial direction and is engaged with the cylindrical face gear in the whole moving range. The gear with the large diameter is installed on the rear end of the long gear. The rotary driving force of the motor is transmitted to the gear with the gear with the large diameter.
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