GB406193A - Improvements in or relating to photographic enlarging apparatus - Google Patents

Abstract

406,193. Photographic enlarging- apparatus. KILBURN, B. E. D., 31, High Holborn, London.-(Leitz, Ges., E. ; Optical Works, Wetzlar, Germany.) July 13, 1933, No. 19843. [Class 98 (i).] Automatic focusing movement is imparted to the objective by a cam which is rotatably mounted on the enlarging unit and is actuated by a lever pivoted on a part which is fixed relatively to the printing surface. In one form, Fig. 1, the objective mount slides in a guide C on the enlarging unit, and carries a roller C<2> movable in a slot C' in the guide C and pressed by a spring against a cam H which is pivoted at H<1> on the guide C and is fast with a lever G pivoted at G<1> to a supporting pillar D. Pivoted at E<2> on the pillar is a link E pivotally supporting the enlarging unit at E<1> and forming with the link G a parallel-motion linkage. As the enlarging unit is raised or lowered above the copy surface F, rotation of the lever G and associated cam H effects the necessary focusing adjustment of the objective. The parts are frictionally held in adjusted position. If the cam H is provided with a cam slot, the spring maintaining the roller C' against the cam is not required. The pillar D is made telescopic to facilitate the initial setting. Modifications are described in which (1) the lever E is replaced by a rigid arm connected to a sleeve slidable on the pillar D, the lever G being in this case slidable through its pivot connection G<1> ; and (2) the link G is not fast with the cam H, but turns on a separate pivot on the guide C and carries a toothed sector engaging a toothed sector turning with the cam H.