| 摘要 |
PURPOSE:To reduce the degradation of the capacity of a lens for enlargement or reduction to prevent this degradation from exceeding an allowable range even in case of requirement specification is severe and to simplify the switching operation, by rotating automatically the lens by 180 deg. to reverse the lens when a lens carriage is moved to an enlargement or reduction position. CONSTITUTION:When a lens carriage 21 is moved to allow a pinion 24 to bite fixed rack teeth 25 and move, a supporting shaft 23 is rotated, and a rotation- side end face cam 34 is rotated also, and therefore, the cam 34 is moved downward against a spring 36 by the ruggedness. When the pinion 24 is rotated by 180 deg. to rotate the supporting shaft 23 by 180 deg., the ruggedness of the rotation- side end face cam 34 is fitted closely to that of a fixed-side end face cam 32 by the shift of 180 deg. in phase, and a lens 12 is rotated by 180 deg. and is positioned surely in the turned-out position. Consequently, since the direction of incidence to the lens is reverse to invert enlargement to reduction, it is unnecessary to use a lens optimum for unmagnification as conventional, and the degradation of the performance of the lens within a range of used mangifications is less than that of a conventional system. |
