Abrading – Abrading process – Glass or stone abrading
Patent
1993-12-30
1996-08-13
Kisliuk, Bruce M.
Abrading
Abrading process
Glass or stone abrading
451 43, B24B 100
Patent
active
055450750
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for the production of an edged ophthalmic lens wherein an ophthalmic lens which initially is finished on one side but not yet edged according to a prescribed disk shape, i.e., a so-called blank having only one finished effective surface, is produced and the so-called prescription surface is produced in another manufacturing step, if need be, including the optimization of the critical thickness.
STATE OF THE ART
Presently, the production of edged ophthalmic lenses usually occurs in several largely separate manufacturing steps:
First a so-called blank is produced by an ophthalmic lens manufacturer. This usually refers to a "raw-round" ophthalmic lens finished on one side. In certain cases, however, the contour of the perimeter of a blank may deviate from the circular shape: therefore it has been proposed to fabricate ellipsoidal-shaped blanks.
The finished, processed surface, sometimes also referred to as the effective surface, is usually the "more difficult-to-produce" surface, i.e. in a progressive ophthalmic lens, the progressive surface or in the case of a toric ophthalmic lens, the toric surface. Following the production of the effective surface, in many cases the blank is "stored intermediately" in a stockroom "near the customer". The second surface, also referred to as the prescription surface and usually a "simple", spherical or toric surface, is not produced until it is specifically ordered. Production of the prescription surface, which often is carried out "near the customer", i.e. decentrally in so-called prescription lens production workshops, usually occurs without taking into consideration the shape of the spectacles into which the ophthalmic lens is to be inserted.
But rather the edges of the ophthalmic lens are processed by the respective optician selling the spectacles to the customer. Only then, when the critical thickness of the ophthalmic lens, i.e. the center thickness in plus lenses, respectively the edge thickness in minus lenses, are to be minimized, "preliminary edging" of the ophthalmic lens, respectively the blank, occurs in conjunction with the production of the prescription surface according to the processes described in the patent literature. With regard to this, reference is made, by way of example, to DE 38 01 384 A1 and the literature cited therein.
These currently practised procedures for producing edged ophthalmic lenses require that a series of steps be executed several times:
By way of illustration, if the lens is to undergo preliminary edging, a necessary production step be it in the prescription lens production workshop or at the optician's, the disk shape of the spectacles has to be determined as a set of data.
Moreover, it is necessary both in the prescription production workshops and at the optician's to hold the lens for processing, i.e. to grip it in such a manner that the lens can be inserted in the respective processing apparatus.
Repeated execution of the same procedures is not only time and therefore cost consuming but also a major source of errors.
DESCRIPTION OF THE INVENTION
The object of the present invention is to provide a process for the production of an edged ophthalmic lens wherein an ophthalmic lens which is initially finished on one side but not yet edged according to a prescribed disk shape, i.e. a so-called blank having only one finished effective surface, is produced wherein the multiple execution of various steps, such as determination and storage of the disk shape of the spectacle frame, are avoided.
A solution to this object according to the present invention is set forth in claim 1. Further improvements of the present invention are characterized in claim 2 and those following.
The present invention is based on the fundamental idea of carrying out the production of the prescription surface and edge processing with an once only determined and stored set of data for the disk shape without renewed gripping of the ophthalmic lens.
For this purpose, the prescribed disk shape is stored
REFERENCES:
patent: 1356330 (1920-08-01), Allen
patent: 2890551 (1959-06-01), Dalton
patent: 3226887 (1966-01-01), Rudd et al.
patent: 4203259 (1980-05-01), Haddock
patent: 4573121 (1986-02-01), Saigo et al.
Banks Derris H.
Kisliuk Bruce M.
Wernicke & Co.
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