| 摘要 |
A system for positioning a load, such as lens 3b in of multiple positions disposed over a linear axis consists of a linear actuator 15 to move the load into each of the positions. A first position 12 is at an end of the movement, with a second position 11 opposite. A third position 13 is intermediate between the first and the second positions. A stop actuator 16 is made of a configurable material switchable selectively between an engaged configuration, in which the load is positioned in the at least third position, and a disengaged configuration, in which the load is freely movable between the first and the second positions. The configurable material may be a shape-memory allow (SMA) forming a gate structure or wire structure or may be an electroactive polymer or a tiny ultrasonic linear actuator (TULA). The device may be used in zoom focus particularly for scanners for reading bar codes. |
