Lens blocking method and related device

1. A method for blocking an optical lens, comprising an upper and a bottom lens surface, on a holding unit using a thermoplastic material layer, the holding unit comprising a bottom part to be inserted and fixed in a lens machining tool and an upper part with an upper assembling surface, where the upper assembling surface is smaller than the bottom lens surface, said method comprising the steps of:

a) providing around the holding unit a removable part comprising an upper part surface which is arranged so as to extend the upper assembling surface of the holding unit and not to contact the bottom lens surface;

b) providing a predetermined volume of a thermoplastic material on the upper assembling surface or on a tape arranged on the upper assembling surface of the holding unit, where the predetermined volume is determined so as to obtain a desired shape and size of the thermoplastic material layer;

c) orienting the lens in a desired spatial configuration;

d) positioning the lens so that its bottom surface or the bottom surface of a tape stuck to the lens bottom surface contacts the thermoplastic material of step b) at a softened or melted state and pressing the lens so as to keep the lens spatial configuration constant and to let the thermoplastic material flow from the upper assembling surface of the holding unit to at least a part of the upper part surface of the removable part and form the desired shape and size of the thermoplastic material layer;

e) removing the removable part from around the holding unit after at least partial consolidation of the thermoplastic material layer,

wherein the holding unit comprises at least an external wall having an axial symmetry, where the symmetry axis is a vertical axis,

wherein the removable part has an axial symmetry with the vertical symmetry axis of the external wall of the holding unit,

wherein the shape of the upper part of the holding unit is a cylinder of diameter D which external wall upper edge forms the perimeter of the upper assembling surface and where the removable part is an annular part which internal wall has a diameter D and can move slidingly along the external wall of the upper part,

wherein the holding unit is chosen within a series of N holding units where the bottom part of each holding unit has the same shape and size and where the upper parts of the N holding units of the series have increasing diameters (D 1 , D 2 , . . . DN) so as to provide N upper assembling surfaces of increasing surface, where N is an integer equal to or greater than 2, and

wherein the removable part comprises at least two co-axial annular sliding parts, each having an internal and external wall, where the internal wall of the first annular sliding part has a diameter D 1 of the external wall of the upper part of the first holding unit of the series, the external wall of said first annular sliding part has a diameter D 2 of the external wall of the upper part of the second holding unit of the series, the internal wall of the second annular sliding part has the diameter D 2 of the external wall of the upper part of the second holding unit and where the upper part surface of the first, and respectively the second, annular sliding part is movable so as to be the upper part surface arranged so as to extend the upper assembling surface of the first, and respectively the second, holding unit.

2. The method of claim 1 , wherein the removable part has a wall slidingly movable on an external wall of the upper part of the holding unit.

3. The method of claim 1 , wherein the removable part can be attached on, and further detached from the holding unit.

4. The method of claim 1 , wherein the holding unit has an axial symmetry with said vertical symmetry axis.

5. The method according to claim 1 , wherein N is equal to or greater than 3 and the removable part comprises N co-axial annular sliding parts where the internal wall diameter of the P annular sliding part is equal to the external wall diameter D(P−1) of the P−1 annular sliding part, the external wall diameter of said P annular sliding part is equal to the diameter of the external wall of the P+1 upper part of the series, where P is at least 2 and equal to or less than N−1, and where the upper part surface of the P annular sliding part is the upper part surface arranged so as to extend the upper assembling surface of the P holding unit.

6. A holding unit blocking device for blocking an optical lens on an upper assembling surface of a holding unit comprising a bottom part to be inserted and fixed in a lens machining tool and an upper assembling surface for securing said lens, comprising a removable part comprising an upper part surface suitable to be arranged so as to extend the upper assembling surface of the holding unit and not to contact the bottom surface of the lens to be secured and wherein the removable part comprises at least two co-axial annular sliding parts each having an internal and external wall, where the internal wall of the first annular sliding part has a diameter D 1 of the external wall of the upper part of a first holding unit, the external wall of said first annular sliding part has a diameter D 2 of the external wall of the upper part of a second holding unit which upper part is larger than the upper part of the first holding unit, the internal wall of the second annular sliding part has the diameter D 2 of the external wall of the upper part of the second holding unit and where the upper part surface of the first, and respectively the second, annular sliding part is movable so as to be the upper part surface arranged so as to extend the upper assembling surface of the first, and respectively the second, holding unit.

7. The holding unit blocking device of claim 6 , wherein the removable part has a wall slidingly movable on an external wall of the upper part of the holding unit.

8. The holding unit blocking device of claim 6 , wherein the holding unit and the removable part have an axial symmetry, where the symmetry axis is a same vertical axis.

9. A holding unit blocking system comprising a holding unit blocking device for blocking an optical lens on an upper assembling surface of a holding unit comprising a bottom part to be inserted and fixed in a lens machining tool and an upper assembling surface for securing said lens, comprising a removable part comprising an upper part surface suitable to be arranged so as to extend the upper assembling surface of the holding unit and not to contact the bottom surface of the lens to be secured and wherein the removable part comprises at least two co-axial annular sliding parts each having an internal and external wall, where the internal wall of the first annular sliding part has a diameter D 1 of the external wall of the upper part of a first holding unit, the external wall of said first annular sliding part has a diameter D 2 of the external wall of the upper part of a second holding unit which upper part is larger than the upper part of the first holding unit, the internal wall of the second annular sliding part has the diameter D 2 of the external wall of the upper part of the second holding unit and where the upper part surface of the first, and respectively the second, annular sliding part is movable so as to be the upper part surface arranged so as to extend the upper assembling surface of the first, and respectively the second, holding unit,

the holding unit blocking system further comprising:

positioning means for the holding unit;

a volumetric batcher for providing a predetermined volume of a thermoplastic material on the upper assembling surface;

means for orientating the lens in a desired spatial configuration; and

means for pressing the lens on the thermoplastic material.

10. The holding unit blocking system of claim 9 , wherein the removable part of the holding unit blocking device has a wall slidingly movable on an external wall of the upper part of the holding unit.

11. The holding unit blocking system of claim 9 , wherein the holding unit and the removable part have an axial symmetry, where the symmetry axis is a same vertical axis.