| 摘要 |
PROBLEM TO BE SOLVED: To prevent the intrusion of dust to a space between a fixed lens group and an imaging element provided at a back (image) side by a simple and low-cost configuration. SOLUTION: In a two group unit 3 which is a fixed lens group, in the holding part 322 of an optical element 32 at the rear (image) side, a step 324 is formed at a part of a circumferential direction on an abutting surface 323 with a rear frame 51, and a notch 326 continued to the step 324 is formed on an outer peripheral surface. Corresponding to that, a notch 316 is formed also at the outer peripheral surface of the holding part 312 of an optical element 31 at the front (object) side. In such a manner, an air path indicated by an arrow F is formed only through the step 324 and the notches 326 and 316, and a space 8 between the two group unit 3 and the imaging element 7 is made to communicate with the outside. Thus, a labyrinth structure to which dust cannot easily intrude is obtained easily at a low cost by existing components without increasing the number of components. COPYRIGHT: (C)2011,JPO&INPIT |
