AUTOFOCUS LENS FOR TELEVISION CAMERA

摘要

PURPOSE:To change a turning force applied to a focusing lens ring into a backward moving force in an optical-axis direction efficiently by composing a driven and a prime driving gear of a spiral bevel gear which has its tooth trace slanted by an angle corresponding to the lead angle of a helicoid. CONSTITUTION:The driven gear 21 is provided to the outer periphery of the focusing lens ring 12 which engages a fixed lens barrel 14 threadably through the helicoid 13, and this driven gear 21 is engaged with the prime driving gear 22 which is driven by a motor 16 to constitute an autofocus lens for a television camera. The driven gear 21 and prime driving gear 22 are composed of a spiral bevel gear having its tooth trace slanted by the angle corresponding to the read angle theta of the helicoid 13.