| 摘要 |
PURPOSE:To allow the execution of recording and reproducing always in a stable state and the smooth execution of elongation and contraction by forming the opening on the stationary optical system side of a hollow member to the sectional shape larger than the sectional shape of a moving optical system side and forming an air path communicating with the inside of the stationary optical system in the aperture of the stationary optical system. CONSTITUTION:A transparent member 11 is positioned and disposed in the part of the apertures 6, 7 where light passes. A plate member 12 is positioned and disposed in the upper part of the transparent member 11 where the light does not pass to form the air path 13. The volume in the space constituted of the moving optical system 2, the stationary optical system 1 and bellows 10, therefore, changes rapidly and the air current C generated in the bellows 10 moves successively through the air path 13 provided in the upper part of the transparent member 11 of the aperture 6 when the moving optical system 2 makes seek motion at a high speed. A rapid change in the atm. pressure in the stationary optical system 1 or the moving optical system 2 is, therefore, eliminated. The disturbance in tracking control and focusing control is obviated in this way and the execution of the recording and reproducing of always the stable state is possible. The smooth execution of the elongation and contraction at the time of the seek motion is possible as well. |
