Focal length adjustment apparatus with improved vibration and impact-resistance properties

A focal length adjustment apparatus with improved vibration and impact-resistance properties, comprising:

• a moving unit including a lens barrel that contains at least one lens therein and is formed with a pair of guide slots therethrough, and a coil arranged on an outer circumference of the lens barrel;
• a fixed unit including a yoke that is provided with an opening for receiving the lens barrel and a pair of guide protrusions to be inserted into the guide slots, respectively, a case into which the yoke is inserted and mounted, and a magnet affixed to the yoke to be arranged adjacent to the coil;
• a supporting member used to elastically support the moving unit relative to the case;
• and
• a viscous fluid interposed between the coil and the magnet to attenuate vibration of the moving unit,
• whereby the moving unit is linearly moved relative to the fixed unit upon receiving an electromagnetic force produced between the coil and the magnet, to adjust a focal length of the lens.