| 摘要 |
PURPOSE:To prevent dust from sticking to a lens surface and also to prevent its external damage by providing a dust-free plate, which covers an aperture lens, over the aperture lens that irradiates a discoid recording material with a fine light beam by stopping down. CONSTITUTION:Aperture lens (5) is arranged opposing to dust-free plate 11, which is normally held on supporting table 13 through supporting shaft 12 while covering lens 5. One end part of dust-free plate 11 is coupled with plunger 15 by pin 13 and the other end part of dust-free plate (11), once solenoid 16 is fed with electric current, rotates upward on supporting shaft 12. As light emitted from light emission diode 17 is out off, an electric signal is sent to the processing circuit to feed electric current to solenoid 16. Thus, dust-free plate 11 is rotated upward in recording and reproduction and then rotated downward after the recording and reproduction so as to cover aperture lens 5, thereby preventing dust from sticking to lens (5). |
