US1734428A - Method of making fused multifocal lenses - Google Patents

Description

Nov. 5', 1929. c. G, HAERING 1,734,428

KING FUSED MULTIFOCAL LENSES Filed Dec. 1, 1926 INVE NTUR Carl G'Haering. BYKWQ his AT TURNEYS Patented Nov. 5, 1929 UNITED STATES PATENT OFFICE,

OARL G. HAERIN G, OF ROCHESTER, NEW YORK, ASSIGNOR TO BAUSCH'G'c LOMB OPTICAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK METHOD OF MAKING FUSED MULTIFOCAL LENSES Application filed December 1, 1926. Serial No. 152,021.

This invention relates to fused multifocal lenses, and has for its object the provision of a simple and efficient method of making fused multifocal ophthalmic lenses.

More particularly, the object is to provide a simple and eflicient method of-making fused trifocal lenses and an improved product.

' Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction and arrangements of parts as will be exemplified in the structure hereinafter described, and the method which will be described, and the scope of the application will be indicated in the following claims.

In the accompanying drawings in which is shown one of the possible embodiments of this invention,

Figure 1 is a front, or face view of a major lens blank;

Figure 2 is a sectional view of a major lens blank and a'minor lens blank or button in position for fusing;

Figure 3 is a sectional view of a major lens blank showinga disc, or button, attached thereto, on the concave side;

Figure 4: is a sectional view of the lens sholwn in Figure 3 after it has been completed, an

Figure 5 is a view of a completed lens in VYldIlCh the button is attached to the convex 51 e.

Similar reference characters refer to sim ilar parts throughout the several views of the drawings.

Referring now to the drawings in detail, 10 indicates a major lens blank provided on its concave side with curved surfaces 12 and 13. 14 indicates a disc, or button, fused on the surfaces 12 and 13; and 15 indicates the completed minor lens. In Figure 5 is shown a lens 16 provided on its convex side with curved surfaces 17 and 18 and having attached thereto the minor lens 19. v

In carrying out my invention, I prefer to first grind a countersink or depression on a face of a major lens blank to provide a surface 12 having a desired curvature. I then grind a second countersink on a portion of surface 12 to provide a surface 13 which may have a greater curvature than the surface 12. These surfaces are ground and polished in a manner well known in the art. The curvatures to which the surfaces are ground are determined by the powers desired. A disc or button composed of a glass having a lower melting oint than the glass of the major blank is t ien ground and polished to provide a surface which may be of substantially the same curvature as the surface 13.

The prepared disc or button 14 is then placed over the curved surfaces 12 and 13 with one edge portion in contact with the major lens blank adjacent the center of said major blank and the outer edge of the curved surface 12, as indicated at 20, and the opposite edge portion spaced from the major blank by means of a wire or other suitable spacing means as indicated at 21. The thickness of the spacing member and the curvatures of the contacting surfaces are such that there is but a single point of contact between the major lens blank and the disc or button. lVhcn the two members have been suitably arranged they are placed in a suitable furnace or muffle and heated to a temperature sufficient to effect melting of the button and fusion of the two members. The fusion starts at the contact point and works progressively toward the spacing member, filling the concavities or countersinks formed by the grinding of the surfaces 12 and 13 and forcing out all air and gas as it proceeds. When the fusion is complete the composite blank is removed and cooled and finished by grinding and polishing the surfaces to secure the desired powers.

The index of refraction of the glass of the minor portion or button is preferably higher than that of the major lens portion.

\Vhile I have shown a major lens blank having a convex surface and a concave surface, obviously I could use a major blank having a surface of any curavture on either side.

The completed lens shown has outer portions which provide distant and near vision fields and an intermediate portion which provides an intermediate vision field, however,

the vision fields may have different relative positions.

From the foregoing, it will be seen that there is herein provided animproved method which embodies the features of this invention and achieves the objects thereof, and by means of which a new and improved trifocal lens is produced.

As many possible embodiments may be made of the above invention, and as many changes might be made in the embodiment above set'forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying-drawings is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. The method of making a multifocal lens which comprises forminga plurality of countersinks on a face of a major lens blank, each of said countersinks forming a separate vision field, and fusing a single minor lens blank on the surfaces .of all of the counter-' curvature than the first curved surface on aportion of the said first curved surface and fusing a single minor lens blank on both of the said curved surfaces. j I

4. The method of making a trifocal lens which comprises providing a portion of a face of a major lens blank with two surfaces of different curvatures, placing a single minor lens blank on the major lens blank with an edge portion thereof in contact with the unaltered portion of the major blank and fusing the blanks to form a composite lens.

5. The method of making a trifocal lens which comprises grinding a countersink on a surface of a major lens blank to form a curved surface, grinding a second countersink on a.

portion of the surface thus formed to pro- 1 vide a second curved surface, grinding amiwhile thus nor lens blank to provide a convex surface having substantially the same curvature as the said second curved surface, placing the prepared minor blank on the major blank:

with its convex surface adjacent the said curved surfaces and with one edge portion of said minor blank in contact with said major blank adjacent an edge of the first countersink and an opposite edge thereof spaced from the major blank, and fusing the blanks positioned to form a composite lens. a 3

6. The process of making a multifocal lens which comprises providing for a vision field a trifocal lens by forming a curved area on a portion of a major lens blank, providing for a second vision field by forming a second curved area on a portion of said first curved area and fusing a minor lens blank to the major lens blank tocover both of said curved areas.

' CARL G. HAERING.

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