GB2230983A - Lens blank mountings - Google Patents
Lens blank mountings Download PDFInfo
- Publication number
- GB2230983A GB2230983A GB9009475A GB9009475A GB2230983A GB 2230983 A GB2230983 A GB 2230983A GB 9009475 A GB9009475 A GB 9009475A GB 9009475 A GB9009475 A GB 9009475A GB 2230983 A GB2230983 A GB 2230983A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lens
- holder
- lens blank
- machine
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
- B24B13/005—Blocking means, chucks or the like; Alignment devices
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
- Eyeglasses (AREA)
Abstract
A spectacle lens blank assembly comprises a lens blank (12) pre-mounted by an adhesive on a disposable plastics holder (10) by means of which the lens blank may be mounted on a surface generator, a grinding machine, a smoothing machine or a polishing machine. Preferably the holder has a standard fitting to attach it on a chuck of the machine. The lens blank assembly is immediately usable on a grinding machine, thereby reducing the time taken in preparing the prescription, without the additional stages of attaching to a holder with the use of molten metal as in the previous process, and thus makes for economy in the manufacture of lenses to meet a particular prescription. <IMAGE>
Description
IMPROVEMENTS IN OR RELATING TO LENS BLANKS
This invention relates to lens blanks, particularly but not exclusively for the manufacture of spectacle lenses.
In the manufacture of spectacle lenses, particularly synthetic plastics material lenses, the practice is to start with a blank for the lens of a nominal diameter and having a convex surface in a ready-finished state. A socalled "blocking" operation is carried out which entails mounting such a blank by the convex surface on a metal lens holder (button) by which it is to be attached to a grinding machine (or generator) so that the required concave surface may be ground in the blank to make the lens conform to the required prescription. In a known blocking operation the lens blank, which may be covered on its convex side by a film of plastics material, is held against a machined hard metal holder which has a part-spherical convex surface, and a low melting point molten metal is poured between it and the lens to form a film which retains the lens on the holder.
In a preferred blocking operation a mould is provided having a die cavity in the shaft of a substantially cylindrical holder. The lens having the plastics film is held against the die cavity and low melting point metal poured into the cavity and allowed to cool. This causes the lens blank to be drawn to the metal holder and held sufficiently secure for subsequent machining.
The lens is then mounted on the grinding machine by means of the holder which has a standard fitting to attach it on a chuck or other holding device on the machine. The machine is set up according to the lens prescription.
A disadvantage of the known blocking process is that the low melting point metal is expensive (at the present moment about 37 per kilogram) and is not all recoverable since the metal can be lost during polishing or by small amounts being spilt on the floor or by splashes on clothing.
Metal is lost either where a hard metal button is used or in the case where the entire button is made of low melting point metal.
The machining of a hard metal holder is expensive and its use is time consuming when blocking.
The operation of forming a low melting point metal holder is also time consuming and requires a sophisticated moulding machine.
It is an object of the present invention to provide a lens blank which avoids the preliminary step of mounting the lens on the holder by low melting point metal.
A further object is to effect a mounting operation of substantial quantities of blank lenses in readiness for immediate application to the generator.
Accordingly the present invention provides a lens blank assembly comprising a lens blank pre-mounted on a disposable holder by means of which the lens blank may be mounted on a surface generator, a grinding machine, a smoothing machine or a polishing machine.
Preferably the disposable holder is formed of synthetic plastics material.
Preferably the lens is attached to the holder with an adhesive which is soluble in a solvent, e.g. water, which will not attack the material of the lens so that the lens may be readily removed from the holder when it is finished.
Preferably a thin sheet of synthetic plastics material is interposed between the lens blank and the holder to protect the pre-finished surface of the lens blank from any unwanted scratching. The sheet may have an adhesive coating on both sides for securing the lens blank to the holder.
In order to promote a full understanding of the above and other aspects of the present invention an embodiment will now be described, by way of example only, with reference to the accompanying drawings in which:
FIGURE 1 shows a side elevation, half in crosssection, of an embodiment of the invention; and
FIGURE 2 shows a view on the arrow II of Figure 1.
As shown in the drawings the embodiment of the invention comprises a lens assembly including a lens blank holder 10 of synthetic plastics material (such as polytetrafluoroethylene or polyvinylchloride, which is formed with a suitable concave front face 11 and a lens blank 12 having a part-spherical pre-finished surface 13 locating within the concave front face. The lens blank 12 is attached to the holder 10 by means of a suitable adhesive, preferably a water-soluble adhesive or a silicone adhesive, with or without the interposition of a thin sheet of plastics material as indicated at 14 to protect the finished surface of the lens blank 12.
The space between the convex surface of the lens and the concave surface of the holder is taken up with the adhesive as the lens blank and holder are squeezed together to eliminate any inaccuracy occurring between the holder and the lens blank. Only about six spherical sizes of plastics holder are required to cover a very wide range of prescriptions.
The holder 10 is provided with a locating web 15 so that when it is mounted on a grinding machine (not shown) the web 15 may be used to identify a particular angular relationship of the lens blank to the chuck of the machine.
When a lens blank 12 is so mounted on a grinding machine, the concave surface of the blank 16 may be ground as to curvature and as to the thickness of the finished lens as required by the prescription to be met. After grinding the lens is removed from the grinding machine attached to the holder 10, and then removed from the holder 10 by the use of a suitable solvent for further processing, such as being cut to a suitable outline to fit a particular spectacle frame.
Pre-mounting of the lens blanks can be carried out in large batches and the lens assemblies stored ready for use.
Thus it can be seen that the invention provides a lens blank which is immediately usable on a grinding machine, thereby reducing the time taken in preparing the prescription, without the additional stages of attaching it to a holder with the use of molten metal as in the previous process, and thus makes for economy in the manufacture of lenses to meet a particular prescription.
Claims (9)
1. A lens blank assembly comprising a lens blank (12) pre-mounted on a disposable holder (10) by means of which the lens blank may be mounted on a surface generator, a grinding machine, a smoothing machine or a polishing machine.
2. A lens assembly as claimed in Claim 1, wherein the holder is formed of a synthetic plastics material (e.g.
pol ytetrafl uoroethyl ene).
3. A lens assembly as claimed in Claim 1 or 2, wherein the lens is attached to the holder with an adhesive which is soluble in a solvent which will not attack the material of the lens so that the lens may be readily removed from the holder when it is finished.
4. A lens assembly as claimed in Claim 1, 2 or 3, wherein a thin sheet of plastics material (14) is interposed between the lens blank and the holder.
5. A lens assembly as claimed in Claim 4, wherein the thin sheet of plastics material is secured by (water) soluble adhesive.
6. A lens assembly as claimed in any one of claims 1 to 5, wherein said holder is formed with a standard fitting for securing the holder of the machine chuck.
7. A lens assembly as claimed in any one of
Claims 1 to 5, characterised in that the holder (10) is provided with a locating web (15) for use in identifying a particular angular relationship of the lens blank to a chuck of the machine.
8. A process for making spectacle lenses comprising
a) forming a batch of holders of plastics material each with a concave mounting surface and a standard fitting for attachment to a machine for subsequent operation,
b) securing by adhesive material lens blanks to said holders respectively, said lens blanks each having a convex surface, to form a batch of lens blank assemblies,
c) storing the batch of lens blank assemblies in a storage place,
d) selecting one lens blank assembly from said storage place,
e) mounting said selected lens blank assembly by its holder on a machine for generating a concave surface or grinding or smoothing or polishing,
f) effecting a machining operation, and
g) removing said lens from said holder.
9. A process for making spectacle frames as claimed in claim 7, wherein the lens blank is removed from the holder by dissolving the adhesive material.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB898910352A GB8910352D0 (en) | 1989-05-05 | 1989-05-05 | Improvements in or relating to lens blanks |
Publications (2)
Publication Number | Publication Date |
---|---|
GB9009475D0 GB9009475D0 (en) | 1990-06-20 |
GB2230983A true GB2230983A (en) | 1990-11-07 |
Family
ID=10656272
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB898910352A Pending GB8910352D0 (en) | 1989-05-05 | 1989-05-05 | Improvements in or relating to lens blanks |
GB9009475A Withdrawn GB2230983A (en) | 1989-05-05 | 1990-04-27 | Lens blank mountings |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB898910352A Pending GB8910352D0 (en) | 1989-05-05 | 1989-05-05 | Improvements in or relating to lens blanks |
Country Status (1)
Country | Link |
---|---|
GB (2) | GB8910352D0 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1994002286A1 (en) * | 1992-07-17 | 1994-02-03 | Minnesota Mining And Manufacturing Company | Method of processing a lens and means for use in the method |
GB2287421A (en) * | 1994-03-04 | 1995-09-20 | Hydron Ltd | Process of preparing lenses |
US7828624B2 (en) * | 2000-01-18 | 2010-11-09 | Ncrx Optical Solutions, Inc. | Method of local manufacture of ophthalmic lens using remotely assembled pre-blocked lens blanks |
US11370175B2 (en) | 2017-06-19 | 2022-06-28 | Essilor International | Optical element, assembly comprising such an optical element and method of manufacturing an optical element |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB583202A (en) * | 1944-08-03 | 1946-12-11 | American Optical Corp | Improvements in supporting devices for lenses and other articles which are to be subjected to grinding, polishing and other operations |
GB1208946A (en) * | 1967-04-06 | 1970-10-14 | Textron Inc | Method of generating a lens |
US4432380A (en) * | 1981-06-24 | 1984-02-21 | Roag | Apparatus for removing optical component blanks from a blocking tool |
EP0141541A2 (en) * | 1983-10-24 | 1985-05-15 | Emi-Mec Limited | Method of manufacturing a contact lens and apparatus for use in the method |
US4686798A (en) * | 1985-06-21 | 1987-08-18 | Sola U.S.A. Inc. | Optical blank carrier for lathing lenses and process therefor |
-
1989
- 1989-05-05 GB GB898910352A patent/GB8910352D0/en active Pending
-
1990
- 1990-04-27 GB GB9009475A patent/GB2230983A/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB583202A (en) * | 1944-08-03 | 1946-12-11 | American Optical Corp | Improvements in supporting devices for lenses and other articles which are to be subjected to grinding, polishing and other operations |
GB1208946A (en) * | 1967-04-06 | 1970-10-14 | Textron Inc | Method of generating a lens |
US4432380A (en) * | 1981-06-24 | 1984-02-21 | Roag | Apparatus for removing optical component blanks from a blocking tool |
EP0141541A2 (en) * | 1983-10-24 | 1985-05-15 | Emi-Mec Limited | Method of manufacturing a contact lens and apparatus for use in the method |
US4686798A (en) * | 1985-06-21 | 1987-08-18 | Sola U.S.A. Inc. | Optical blank carrier for lathing lenses and process therefor |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1994002286A1 (en) * | 1992-07-17 | 1994-02-03 | Minnesota Mining And Manufacturing Company | Method of processing a lens and means for use in the method |
US5520568A (en) * | 1992-07-17 | 1996-05-28 | Minnesota Mining And Manufacturing Company | Method of processing a lens and means for use in the method |
GB2287421A (en) * | 1994-03-04 | 1995-09-20 | Hydron Ltd | Process of preparing lenses |
GB2287421B (en) * | 1994-03-04 | 1997-09-03 | Hydron Ltd | Process of preparing lenses |
US7828624B2 (en) * | 2000-01-18 | 2010-11-09 | Ncrx Optical Solutions, Inc. | Method of local manufacture of ophthalmic lens using remotely assembled pre-blocked lens blanks |
US11370175B2 (en) | 2017-06-19 | 2022-06-28 | Essilor International | Optical element, assembly comprising such an optical element and method of manufacturing an optical element |
Also Published As
Publication number | Publication date |
---|---|
GB8910352D0 (en) | 1989-06-21 |
GB9009475D0 (en) | 1990-06-20 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |