| 摘要 |
PURPOSE: To improve transfer efficiency of the data and to miniaturize and thin a pickup device by setting a length of a line segment linking a center of an objective lens with the center of a rotary drum provided in a rotary optical part in the length prescribed by the length in the long side direction of an optical card recording surface and 1+cos(θ/2). CONSTITUTION: Reflection mirrors 19, 20 and the objective lens 21 leading a light beam outgoing from a fixed optical part SOP to the recording surface of the optical card 24 are placed on the rotary drum 22 of the rotary optical part ROP, and the rotary motor 23 of the rotary drum 22 is arranged also. At this time, by setting the length of the line segment linking the center of the objective lens 21 with the center of the rotary drum 22 based on the length in the long side direction of the optical card recording surface and 1+cos(θ/2), an optimum rotational radius for the size of the optical card is obtained. |
