| 摘要 |
PURPOSE:To widen the range for the service temp. of a plastic lens and to prevent the clatters of the lens by interposing a member of a small coefft. of friction in the contact part of the lens and correcting the change in the radius of curvature of the lens owing to a change in temp. CONSTITUTION:A friction washer 5 for a rear part is formed like a plane sheet in the fitting part 5 formed on the inside wall of the body mounting part 4 of a lens barrel. Said washer is formed of a blank material of ''Teflon '' base having 0.08-0.15 coefft. of friction. A plastic lens 7 is fitted into the part 5 and is brought into abutment on a friction washer 9. A friction washer 10 for a front part is inserted into the lens barrel and a retaining ring 1 is screwed to a screw part 3 to fix a screw washer 10 and the lens 7. Since the change in the radius of curvature of the lens 7 owing to a change in temp. is absorbed by the washer 9, 10, the service temp. of the lens 7 is widened, and the clatters of the lens are prevented. |
