| 摘要 |
A positive pressure focus lock for closed circuit video cameras. The carrier block to which the image sensing device is attached is moved parallel to the lens axis for focusing images at close range because of the use of a lens normally focused at infinity or changes of focus required by system tolerances. The carrier block motion is accomplished by the use of two cams on a single fixed axis. The cams press against the carrier block and move the carrier block on guide rods as the cam shaft is turned. To prevent play in the movement of the carrier block due to manufacturing tolerances on the various parts, the cams are held tightly against the carrier block by leaf springs instead of using a conventional fixed cam guide. The leaf springs' ends are attached to the carrier block and the springs act as a second bearing surface for the cams while keeping the carrier block tight against the cams regardless of tolerances or shock and vibration.
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