| 摘要 |
PURPOSE:To improve the stability of rotation without generating the inclination of an axial center and to facilitate the change in the design of an attenuation characteristic by providing a means for attenuating the vertical movement of a rotating body with a small hole which is opened on a stationary shaft and communicates with an air supply path. CONSTITUTION:This rotary polyhedral mirror device is formed with the rotating body 2 of a capped cylindrical shape to be fixably fitted on the stationary shaft 1 and is formed with an attenuating means 9 consisting of the orifice which is opened atop 4 the top wall 10 of the stationary shaft 1 and communicated with the flow passage 8a of the air supply path 8 on this top wall. The volume of the space segmented within the rotating body 2 is fluctuated by the upper surface 4 of the stationary shaft 1 when the rotating body 2 and the polyhedral mirror 3 move vertically during rotation. The air to be supplied into the rotating body 2 via the air flow passage 8a flows into this space. The flow of the air arises within the attenuating means 9 between this space and the air flow passage 8a when the change in the volume of the space arises. The flow of the air is suppressed by the flow passage resistance of the attenuating means 9 in such a manner, by which the energy of the vertical movements of the rotating body 2 and the polyhedral mirror 3 is absorbed and the vertical movements thereof are attenuated. |
