| 摘要 |
PURPOSE:To enable to approach the optical system to the recording surface and to enable the information processing with higher accuracy, by forming the light transmission window which transmits beam light over radial direction to the enclosed case of the disc unit. CONSTITUTION:The concave 22 is formed over the radial direction of the upper cover 10b of the enclosed case 10 and the light transmitting window 23 made of slits is formed at the bottom near the recording surface 5a of the disc 5 of the concave 22. The window 23 is closed with the protection plate 24 made of the material less in the absorption of laser light and air-tightness is held. The lower and upper covers 10a, 10b have the construction that they are inserted to the open ends and the packing 25 is inserted on the mating surfaces. The enclosed case 10 containing the disc 5 is ensured for air-tightness. Thus, the information processing with higher accuracy can be made. |
