| 摘要 |
PURPOSE:To make it possible to prevent the deterioration of sensitivity of a driving section and to increase upper limit value of allowable current of the coil by attaching a ventilable filter to at least one of an enclosure and an enclosure cover. CONSTITUTION:When a driving section including an objective lens 1 and a coil 4 is moving in the direction of driving (a), (b), the driving section exerts effect like a piston and accordingly, the air inside of a container made by the cover 3, the enclosure 7 and the enclosure cover 16 of an objective lens driving device is compressed and expanded. However, due to air permeability of a member for ventilation 5 itself made of porous material, the compression and expansion of the air are relieved and the resonance of the cover 3 of the objective lens driving device in high frequency band is suppressed and resonance sound generated during the action of the objective lens driving device is lowered. As the variation of pressure inside of the container becomes small, the deterioration of sensitivity of the driving section can be prevented and the air permeability of the filter 5 for ventilation can enhance heat radiation effect of the coil 4. Thus, the upper limit value of allowable current of the coil can be increased. |
