| 摘要 |
A lens assembly for positioning on a guide rod 4 has a lens cell 10 and a permanent magnet assembly 12 connected to the lens cell 10. The permanent magnet assembly 12 has a permanent magnet 20 for applying a close-coupled magnetic force on the guide rod 4 to hold the lens cell 10 at a desired position along the guide rod 4. The permanent magnet 20 is V-shaped with a north pole, a south pole, and a recessed longitudinal channel in-between for receiving the guide rod 4 in close proximity. The magnet 20 also has a plurality of rotational guide bearings 22, 24, 26, 28, each rolling against an underside of the guide rod 4 to guide the lens cell as it is moved along the guide rod. The permanent magnet assembly 12 also has an aperture 30 therein in which the guide rod passes through to secure the lens assembly 2 from releasing from the guide rod when shock loading exceeds the closed-coupled magnetic attraction force.
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