Patent GB-1464532-A (GB)
IPC: G02C13/00
Filed: 1976-01-06
Abstract: 1464532 Contouring lenses ESSILOR INTERNATIONAL COMPAGNIE GENERALE D'OPTIQUE 6 Jan 1976 [10 Jan 1975] 00367/76 Heading B3D A feeler for apparatus for reading the contour of a bezel 14, Fig. 5, of a spectacle frame rim 11 comprises an axially elongated rod 15 carried by a support 21 and provided with a reading head 20 which is adapted to co-operate with the bezel, the support carrying at one end the inner annular element 32 of a ball joint 33 whose outer annular element 34 is carried by a fixed base 35, the support also carrying a cylindrical skirt 38 which is disposed coaxially around the support and the free edge of which co-operates with the base and at least one displacement detector 40. In a known apparatus, the spectacle frame 12 is clamped to a support plate 10 and its contour is read by a feeler 15 which controls a tool for cutting a lens to fit the frame or an intermediate template, the tool being carried by a second plate fixed to the plate 10 which serves as a guiding means. The feeler 15 has a reading head 20 of a dihedron cross-section for engaging the bezel 14 of the frame and is axially and rotatably mounted in a tubular support 21 fixed to a base 24, the axial movement accommodating the meniscus of the lens. The base is mounted on pivot pins 25 for movement about an axis B and has lateral arms 28 which co-operate with displacement detectors 29. A displacement control means 18 on the plate 10 effects translational movement of the plate 10 in the direction of the arrow F1 to apply the rim 12 against the feeler 15 and for translatory rotation about the axis of the rim in the direction of the arrows F2. The detectors 29 may be photo-electric or electromagnetic and respond to displacment of the base 24 about the axis B, when the tangential plane passing through the point of contact of the reader 20 with the rim 12 is not perpendicular to the plane containing the axis A of the feeler and the axis B of the pivot pins 25, to actuate the displacement means to bring the tangential plane perpendicular to the plane containing the axes A, B. In another known apparatus, the feeler is mounted on a shaft pivotable about an axis normal to the axis of the feeler. The feeler of the present invention is mounted by the ball joint 33, Fig. 5, on a fixed base 35 so as to be pivotable about two axes different from its own axis and orthogonal to each other. The feeler is axially slidable, to accommodate the meniscus of the lens, in the support 21 which carries the inner element 32 of the ball joint, the outer element 34 being mounted in the fixed plate 35. The cylindrical skirt 38 is mounted on the support and, when at rest, is at all points the same distance from the base 35. When the feeler is subjected to rocking motion, the skirt co-operates with at least one displacement detector 40 which causes rotation of the plate 10, Fig. 1 about the contact point between the reader 20 and rim 12. In another embodiment, the base is oblique so that, when at rest, the skirt contacts the base at one point. Pin base may be convexly curved. The displacement detectors may be mounted on plates adjustable perpendicularly to the base or may be pivotally adjustable by micrometer screws.