Lens blocker

摘要

A computer is used to calculate the location of a target, customize the target to conform to the lens, frame and patient characteristics of each individual job and automatically compensate for parallax in the apparatus. A convenient open work surface is provided for the operator to position the lens blank on a non-skid surface. The block is applied at a constant limited force in a manual or automatic mode of operation on either frame or optical center. The offsets for positioning the lens blank are calculated within the blocker based upon frame and patient data. This data can be input directly or can be downloaded from a database. These offsets determine the location of the target relative to the optical markings on the lens blank. The amount the target is offset is scaled automatically to compensate for the fact that the lens blanks are on a work surface above the electronic display. A customized target is displayed. The target is scaled to match the segment widths for multi-focal lenses, and provides a centered target location with multiple horizontal lines for single vision lenses, including progressive lenses. Scaling of the width eliminates operator judgement to "eyeball" the center. The multiple horizontal lines provide an additional aid in aligning progressive lenses where the distance from the "mounting cross" to the horizontal line on the lens blank varies by manufacturer. The frame shape may also be displayed to provide a sense of fit.