| 摘要 |
PURPOSE:To preserve the performance of an optical parts in an excellent state in an optical information recording and reproducing device converging a beam from a light source on an information recording medium by an objective lens and recording, reproducing or erasing the information. CONSTITUTION:A port 2 is formed on a surface where a protection member 1 covering an objective lens driving device is orthogonally crossed with an axial line O6-O6 and on a position where the objective lens is faced, and plural objective lenses 4, 7 are provided on a rotating body 3 and on the positions symmetrical each other regarding the axial line O6-O6 as a symmetrical center. The relational positions of respective objective lenses are decided so that the remaining objective lens exists on the position covered by the protection member 1 when only one among these objective lenses exists on the position facing to the port 2 on the protection member 1. |
