A method of and an apparatus for manufacturing an optical lens

Abstract

A method and apparatus for blocking an unfinished optical lens member on a blocker for manufacturing an optical lens from the unfinished optical lens member, the latter being provided with a finished surface having a first reference frame, the blocker having a second reference frame, includes: placing the unfinished optical lens member on the blocker; measuring the relative positioning of the first reference frame of the finished surface of the placed unfinished lens member with respect to the positioning of the second reference frame of the blocker; comparing the measured relative positioning with a predetermined relative positioning to determine a relative positioning shift; moving at least the blocker and/or the lens member to change the relative positioning of the first reference frame with respect to the second reference frame to compensate for the relative positioning shift; and blocking the unfinished lens member on the blocker at the changed relative positioning.

1 . A method of blocking an unfinished optical lens member on a blocker for manufacture of an optical lens from the unfinished optical lens member, the unfinished optical lens member being provided with a finished surface having a first reference frame and the blocker having a second reference frame, the method comprising:
 placing the unfinished optical lens member on the blocker;   measuring the relative positioning of the first reference frame of the finished surface of the placed unfinished optical lens member with respect to the positioning of the second reference frame of the blocker;   comparing the measured relative positioning with a predetermined relative positioning in order to determine a relative positioning shift;   moving at least one of the blocker and the lens member so as to change the relative positioning of the first reference frame with respect to the second reference frame to compensate for the relative positioning shift; and   blocking the unfinished optical lens member on the blocker at the changed relative positioning.   
     
     
         2 . A method according to  claim 1 , wherein the blocker is provided with a movable part operable to move the second reference frame and changing the relative positioning of the first reference frame with respect to the second reference frame comprises moving the movable part to move the second reference frame. 
     
     
         3 . A method according to  claim 1  wherein:
 the finished surface of the optical lens member is provided with one or more first detectable identification features associated with the first reference frame and the blocker is provided with one or more second detectable identification features associated with the second reference frame; and 
 the step of determining the relative positioning comprises detecting the positions of the first one or more detectable identification features and the second one or more detectable identification features. 
 
     
     
         4 . A method according to  claim 1 , wherein one of the reference frames is moved with respect to the other reference frame according to at least one of the following positioning parameters: decentration Tx of the centration point of the reference frame, decentration Ty of the centration point of the reference frame; orientation Rz of the reference frame about the vertical z axis of the lens member, orientation Rx about the horizontal x axis of the lens member and orientation Ry about the horizontal y axis of the lens member. 
     
     
         5 . A method according to  claim 4  wherein one of the reference frames is moved with respect to the other reference frame along a vertical translation so that the relative positioning parameter ΔTz between the two reference frames corresponds to a predetermined relative positioning parameter ΔTz predet . 
     
     
         6 . A method according to  claim 5  wherein measuring the relative positioning comprises measuring the positioning parameters Tx, Ty and Rz by means of a first camera positioned according to a camera reference frame. 
     
     
         7 . A method according to  claim 6 , wherein measuring the relative positioning comprises measuring the positioning parameters Rx, Ry and/or T z  through at least one second camera positioned with respect to the said camera reference frame. 
     
     
         8 . A method according to  claim 6  comprising positioning the first and/or second camera with respect to camera reference features provided on the blocker. 
     
     
         9 . A method according to  claim 5  comprising a machining tool positioning step wherein the speed of approach of the machining tool towards the unfinished surface is determined based on the relative positioning parameter Tz of the two reference frames. 
     
     
         10 . A method according to  claim 1  wherein the predetermined relative positioning is determined based on prescription data including at least one of addition, prism and lens thickness data. 
     
     
         11 . An apparatus for blocking an unfinished optical lens member for manufacture of an optical lens from the unfinished optical lens member, the unfinished optical lens member being provided with a finished surface having a first reference frame; the apparatus comprising:
 a blocker having a second reference frame, on which, in use, the unfinished optical lens member is placed;   a measuring device for measuring the relative positioning of the first reference frame of the finished surface of the placed unfinished optical lens member with respect to the positioning of the second reference frame of the blocker;   a calculation module for comparing the measured relative positioning with a predetermined relative positioning in order to determine a relative positioning shift; and   a positioning device for moving at least one of the blocker and the lens member so as to change the relative positioning of the first reference frame with respect to the second reference frame to compensate for the relative positioning shift; wherein the blocker is operable to block the unfinished optical lens member at the changed relative positioning.   
     
     
         12 . An apparatus according to  claim 11  wherein the blocker comprises a movable part movable by the positioning device to change the relative positioning. 
     
     
         13 . An apparatus according to  claim 12  wherein the movable part is movable according to at least one of the positioning parameters Tx, Ty, Rz, Rx and Ry. 
     
     
         14 . An apparatus according to  claim 11  wherein the blocker comprises a movable part movable along at least the direction Tz so that Tz matches a predetermined Tz predet . 
     
     
         15 . A computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing a method according to  claim 1  when loaded into and executed by the programmable apparatus. 
     
     
         16 . An apparatus according to  claim 12  wherein the blocker comprises a movable part movable along at least the direction Tz so that Tz matches a predetermined Tz predet . 
     
     
         17 . A method according to  claim 2  wherein:
 the finished surface of the optical lens member is provided with one or more first detectable identification features associated with the first reference frame and the blocker is provided with one or more second detectable identification features associated with the second reference frame; and 
 the step of determining the relative positioning comprises detecting the positions of the first one or more detectable identification features and the second one or more detectable identification features. 
 
     
     
         18 . A method according to  claim 4 , wherein one of the reference frames is moved with respect to the other reference frame according to at least one of the following positioning parameters: decentration Tx of the centration point of the reference frame, decentration Ty of the centration point of the reference frame; orientation Rz of the reference frame about the vertical z axis of the lens member, orientation Rx about the horizontal x axis of the lens member and orientation Ry about the horizontal y axis of the lens member. 
     
     
         19 . A method according to  claim 4  wherein measuring the relative positioning comprises measuring the positioning parameters Tx, Ty and Rz by means of a first camera positioned according to a camera reference frame. 
     
     
         20 . A method according to  claim 7  comprising positioning the first and/or second camera with respect to camera reference features provided on the blocker.