The present invention concerns a combined grinding and marking-out former for lenses for eye glasses of the type where the lenses themselves have holes, slits or similar slots for fixation elements for parts of the frame.

Lenses of this type particularly form part of modern wire glasses, for instance with frame parts of titanium, as known in various manufactures from the published international patent applications WO 87/04806 and WO 92/08158.

In glasses of this type, aesthetic considerations require that the openings or holes in the lenses used for receiving the fixation elements for frame parts, such as side bars and bridge are shaped symmetrically in the two lenses, which, however, is difficult using known manual marking-out methods, where the lens itself usually is placed on top of the former, where the placement of the slots or the holes is graphically marked. As these marks, during the marking, are read through the lens, the marking-out itself on the up¬ turned side is laborious and time-consuming, requiring great experience to compensate for the optical dis¬ placement, due to the refraction in the lens. The present invention aims at producing a faster and considerably more accurate symmetrical marking-out of holes, slits and similar cuts than possible with the above described marking-out method.

In this respect, the combined grinding and marking-out former is particular, in accordance with the present invention, by being a disc shaped element having mirror symmetrical depressions on both sides, with an outer contour similar to the desired shape and size of the lenses in a pair of eye glasses, said depressions

being each surrounded by an elevated rim with a constant width, and drilled bores being provided in the partition between the two depressions for marking-out of said holes, slits or similar slots in a lens positioned in one of the depressions by aid of a marking tool, which is conducted through said marking bore from the opposite depression.

Using this grinding and marking-out former, one will first do a grinding of the rim of the lenses to the desired size and outer contour of the lens by means, known per se, which typically is done using a copy grinding method, where the grinding tool is forced to follow a track determined by the outer contour of the grinding and marking-out former. To make the subsequent positioning of the lens possible in one of the depres¬ sions of the former, the grinding tool is adjusted to make the grinding in such a manner as to compensate for the constant width of the rim of the former, which for instance may be 2.5 mm, by which the lens is grind with a rim corresponding to the outer contour of the grinding and marking-out former less the said constant width.

When marking holes, slits or similar slots in the two lenses of a pair of eye glasses, first one glass is positioned in one depression of the former and the marking-out is implemented in the manner described by means of a marking tool, which will be conducted through the partition for direct marking-out of the back of the lens. This operation will subsequently be repeated with the other lens positioned in the other depression, using the same bores in the partition for the marking-out, and so as to make the marking-out exactly mirror symmetrical for the two lenses.

The invention is explained in more detail in the following, with reference to the drawings, where fig 1 shows a plane view of an embodiment of the

grinding and marking-out former; and fig 2 a sectional view along lines II-II in fig 1.

As can be seen on the drawing, the grinding and marking-out former is designed as a disc shaped element 1, which on both sides has depressions 2 and 3 with an outer contour corresponding to the desired shape and size of the two lenses in a pair of eye glasses.

Each depression 2 and 3 is surrounded by an elevated rim, 4 and 5, respectively, with a constant width (a), which assures that the grinding of the outer contours of the lenses by use of the former as a grinding former may be done in such a way as making the cut outer contour exactly fit the outer contour of the corresponding depression 2 or 3 in the former. As the depressions 2 and 3 are done mirror symmetrically, the elevated rims for the two depressions 4 and 5 will naturally be integral.

In the partition 6 between the depressions 2 and 3 drilled bores 7 and 8 are provided which, in the product shown, may serve for marking-out of screw holes in lenses for eye glasses of the kind mentioned in the above publicized international patent application WO 92/08158.

The marking-out is done in a way such as after positioning the lens in a depression, a marking tool, for instance a pen or a mandrel is conducted through the bores 7, 8 from the opposite depression 3 ^\' for marking-out on the back of the lens supported against the partition 6. Instead of the marking bores 7, 8, there may be other forms of marking bores, for instance for marking- out of fixation slits used in the lenses in eye glasses versions of the kind mentioned in the above published international patent application WO 87/04806. The shape of the former, including the shape of

the depressions 2 and 3, may be adapted to any desired shape of lenses, just as the height of the elevated rims 4 and 5 may be adapted in accordance with the thickness of the lenses and with due considera¬ tion to the curvature of the lenses.