GB851451A - Coupling means for the detachable assembly of component parts of apparatus, especially photographic cameras - Google Patents

Abstract

851,451. Photographic cameras; lens mounts. AGFA A. G. July 16, 1957 [Sept. 14, 1956], No. 22567/57. Classes 97(1) and 98(1) [Also in Group XXV] In coupling means for the detachable assembly of parts of apparatus, wherein one part has a ring resilient in its own plane, which engages a conical surface on a second part which is thereby caused to seat on the first part, the angle between the generator of the conical surface and the plane of the ring being greater than zero but smaller than the angle at which a force pulling the first component away from the second will provide a component acting on the ring in excess of the friction between the ring and the conical surface, and between the ring and one part; and a release member is movable to deform the ring to allow a separation of the parts. As shown in Fig. 1 and 2, a ring 3 is secured to the camera body 1 by means of screws 2. The gapped resilient ring 7 is located between the ring 3 and a second ring 5 which is trapped between the ring 3 and the mount 1. Spring ring 7 engages a conical surface 4a formed on the objective mount 4. The angle of the generator of the conical surface 4a with the plane of the ring is made sufficiently small that if the objective mount is pulled axially, the friction between ring 7 and the conical surface 4a and the surface of the ring 3 prevents the ring from being moved outwards by camming action on the conical surface 4a, the ring 7, therefore, being strongly resilient. To release the objective the ring 7 may be opened by action of a slidable wedge 9. To reduce local wear on the ring, the parts 7c, where great pressure would otherwise be exerted on the conical surface 4a, are cut away. A further conical surface 4c is formed on the objective mount, with the angle between its generator and the plane of the ring 7 much greater than the maximum angle of the conical surface 4a, so that the objective may be pressed into place. To locate the objective against rotation, a resilient tongue 5b is formed on the ring 5. On insertion of the objective mount, the tongue will in general be depressed, but on rotation it will snap into a corresponding recess on the objective mount. In modifications: (1) the objective mount is formed with pins which bear on recesses mounted in the camera body; (2) the ring 3 has an oblique surface on which the spring ring tends to climb when the objective mount is rotated.