Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-08-07
2004-11-02
Von Buhr, Maria N. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S175000, C451S042000
Reexamination Certificate
active
06813536
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to computer numerical control (CNC) of spectacle lens machining.
2. Relevant Art
Despite far-reaching automation, known CNC spectacle lens machining apparatuses, in particular spectacle lens edging machines, require a CNC-controlled particular accuracy, and therefore skill, for example in inserting into the apparatus a lens blank to be machined, and/or are demanding and complicated to operate as regards inputting the parameters required for the spectacle lens machining, which are a function of the optometric data of the spectacle wearer, the selected spectacle frame, the spectacle lens material and the like.
In the known CNC spectacle lens machining apparatuses, it stills happens that a finally machined spectacle lens cannot be inserted into the selected spectacle frame, and therefore has to be remachined.
The problem on which the invention is based is to create a method for machining spectacle lenses by means of a CNC spectacle lens edging machine, by means of which the operation of the CNC spectacle lens machining apparatus is simplified and made easier, and by means of which an increased accuracy is achieved for the shaped spectacle lens.
Furthermore, the invention is based on the problem of improving a CNC spectacle lens machining apparatus such that operation is substantially simplified in conjunction with increased machining accuracy.
BRIEF DESCRIPTION OF THE INVENTION
Starting from this formation of the problem, a method is disclosed for machining spectacle lenses by means of a CNC spectacle lens machining apparatus which comprises, according to the invention, the steps of:
inputting the optometric data of the spectacle wearer, that is to say dioptric number, values and angles of a cylindrical or prismatic cut, intensity and position of a reading portion, into a computer which cooperates with a control device of the apparatus,
inputting the eye's viewing point or interpupilary distance (PD values) of the spectacle wearer into the computer by means of a selected spectacle frame,
inputting the shape data of a selected spectacle frame, if appropriate of the profile, the shape and the circumference of a bevel groove of the spectacle frame or of a spectacle lens groove or a spectacle lens dubbed corner, corresponding to the spectacle frame, into the computer,
inputting the spectacle lens material, that is to say silicate glass or plastic such as CR39 or polycarbonate, into the computer,
calculating the required lens blank diameter in the computer and displaying the lens blank diameter,
inserting a lens blank of the desired diameter into the apparatus,
if appropriate, checking the position of the lens blank inserted into the apparatus, and incorporating the position of the lens blank by calculation in the machining data,
if appropriate, calculating the profile of a bevel, a groove or a dubbed corner on the shaped spectacle lens from at least one of the following parameters: optometric data, PD values, shape data, radii of the front surface and rear surface and the center thickness of the spectacle lens,
if appropriate, comparing the shape of the bevel groove in the selected spectacle frame with the shape of the bevel groove in a spectacle lens edging tool in the machine, and deciding by computation whether the machining of the bevel is or is not possible without or with taking account of correction values by computer,
CNC machining of the lens blank, which comprises at least shaping the spectacle lens and, if appropriate, also machining a bevel, a spectacle lens groove or a spectacle lens dubbed corner, if appropriate also machining the optical surface(s), it being advantageous that it is possible for correction values to be incorporated by calculation into the machining data before the CNC machining of the lens blank as a function of prescribed machining tolerances, workpiece tolerances and tool tolerances and detected deviations thereof.
In addition to these steps, there can be performed on a screen a monitoring display of the input values and of the required lens blank diameter, and a positionally accurate imaging of the lens blank and, superimposed thereon, of the shape of the spectacle lens, such that all the parameters required for the spectacle lens machining can be checked visually.
When the bevel groove in the spectacle frame and the bevel resulting from the bevel groove in the spectacle lens edging tool are imaged and assigned on the circumference of the spectacle lens on a screen, it is further possible for the feasibility of the bevel machining to be checked visually.
In order to relieve the operator from particular attentiveness and care when inputting the parameters, inputting the dats required for spectacle lens machining can preferably be performed in machine-readable form, the required data can be stored at least partially on at least one data medium such as a magnetic strip card, bar code card or a floppy disk.
Again, the PD values need not be input alphanumerically into a keyboard when the PD values are determined by an automatic video recording system and the data determined are led directly into the computer of the control device. If the shape data of a selected spectacle frame are not available stored on a data medium, the shape data of a selected spectacle frame, including the bevel profile, the bevel shape and the circumference, can be determined in a contactless fashion in a scanning device and led directly to the computer.
When the dimensions and the shape of the bevel groove in the spectacle lens edging tool are determined in a preferably contactless fashion by a video recording system or laser scanner system, and these data are led directly to the computer, it is possible to use the computer to establish whether a bevel can be produced on a spectacle lens, which is to be shaped, in accordance with the dimensions and the shape of the bevel groove in the selected spectacle frame with the aid of the existing spectacle lens edging tool as a function of the wear of the bevel groove in the spectacle lens edging tool, if appropriate with incorporation of a correction value by calculation.
In order to calculate the bevel profile on the circumference of a spectacle lens which is to be shaped, either it is possible for the profile of the front edge and the rear edge of a spectacle lens, which is to be shaped, to be scanned in the apparatus, preferably in a contactless fashion by means of a video recording system, whereupon the data are led directly to the computer, which calculates therefrom the profile of a bevel suitable for the selected spectacle frame and uses these values to control the bevel machining; or the profile of the front edge and of the rear edge of a spectacle lens corresponding to a selected spectacle frame are calculated by the computer using at lease one of the parameters of: optometric data, PD values, shape data, radii of the front surface and rear surface and the center thickness, which calculates therefrom the profile of a bevel suitable for the selected spectacle frame and uses these data to control the bevel machining, the profile of the front edge and of the rear edge can preferably be calculated from the radii of the front surface and rear surface along with the center thickness, and/or can be taken over from a computer for the surface machining. This computer for surface machining can be the same computer as for the edge machining.
The input and calculated data can be conveyed to a spectacle lens manufacturer as order data for the lens blank by long-distance data transmission, such that after the ordered lens blank has arrived, it is possible to perform the final machining of the lens blank in a spectacle lens machining apparatus attached to the computer.
It is also possible for the input and calculated data to be conveyed to a spectacle lens manufacturer as order data for a finally machined spectacle lens by means of long-distance data transmission, such that after the arrival of the finally machined spectacle lens all that is required is for the op
Ostrolenk Faber Gerb & Soffen, LLP
Wernicke & Co. GmbH
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