Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Continuous rim mounting
Reexamination Certificate
2000-04-19
2001-06-05
Mai, Huy (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Continuous rim mounting
C351S086000, C351S154000, C351S178000
Reexamination Certificate
active
06241353
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to methods for making a central piece of a full-rim frame for eyeglasses and more particularly to methods for making a central piece wherein the full rims elastically conform to the peripheral contour of an inserted lens.
BACKGROUND OF THE INVENTION
A central piece for full rim frames is known. It is customarily assembled together with two temples to form an eyeglass frame, the temples being articulated to the central piece with the assistance of hinges arranged on the endpieces. If not only the central piece but also the earpieces are made of plastic, the result is a plastic frame. Once the two lenses have been inserted into the central piece, each of the two frame rims of the central piece completely surrounds the corresponding lens around its entire circumference. Such a frame rim completely surrounding the lens around its entire circumference is customarily, and here as well, called a “full rim.” Accordingly, an eyeglass frame whose central piece has full rims is known as a full-rim frame. One of the advantages of a full-rim frame is that the lenses are protected around their edges against damage from impact or the like.
The known central piece is customarily produced by pressing a plastic material in an appropriate molding tool. One plastic frequently used for this purpose is an epoxy resin sold under the name “Optyl.” The shape of the known central piece is predefined by the molding tool. Owing to the characteristics of the plastics customarily used for the known central piece, in combination with the dimensions of the central piece, this piece is a relatively rigid body whose form is essentially unchangeable. The course of the inner contour lines of the two full rims determines the so-called lens shape, i.e., the lineaments or shape of the outer circumferential lines of the lens to be set into the full rims. The shape of the left lens and the shape of the right lens are as a rule not congruent. However, in conventional eyeglasses with a full-rim frame, they are always symmetric to one another with reference to a vertical line through the middle. Hence in ophthalmic optics it is customary not to distinguish the shape of the left lens from the shape of the right lens, but rather to consider these a single lens shape. In the course of producing a pair of eyeglasses, the lens shape defined by the full rims of the central piece of the eyeglass frame is imaged on two lens blanks in such a way that the lens shape matches the course of the inner contour line of the corresponding full rim, so that the full rims can accept and retain the lenses. Since the lens shape is predetermined by a known central piece of the type under consideration here, it is necessary to produce appropriately varying central pieces to fit various lens shapes.
Also known are rimless frames for eyeglasses, which have no frame rims. In such frames, the lenses are an integral structural component of the central piece of the frame. The endpieces and bridge of a pair of eyeglasses with a rimless frame are joined to the lenses by screws, adhesive or the like. The lens shape is not predefined in a rimless frame. Rather, lenses of different shapes may be assembled together to make different eyeglasses, using the same bridges and endpieces. But in a pair of eyeglasses with a rimless frame, the edges of the lenses are not protected. Furthermore, at the points where they are joined to the bridge and endpieces, the lenses are subjected to locally elevated mechanical stress, which results in an increased risk of breakage.
Furthermore known are half-rim frames which only partially surround the lenses. The central piece of such a half-rim frame has two partial rims, extending from the bridge to either endpiece, which receive the lens around part of its circumference. Around the other portion of the circumference of the lens runs a plastic filament which is anchored to the two ends of the corresponding partial rim with the assistance of anchoring mechanisms. Such a half-rim frame defines the lens shape, at least along the section of the lens edge engaged by the partial rim.
SUMMARY OF THE INVENTION
The invention has the object of further configuring the central piece according to the definition of species, in such a way that it is not exclusively suited to a specific shape of lens alone. The advantages of a central piece with two full rims, particularly its protective function for the lenses and comparatively low mechanical stress on them, are to be largely maintained. Yet at the same time, there should be no need to produce, for each desired lens shape, a central piece suited exclusively for that shape.
According to the present invention, this object is accomplished by a central piece having two full rims that are flexible, and are constituted by a closed, elastic band.
The flexibility or pliability of the full rims makes it possible to modify their shape within wide limits, without destroying the central piece. This means that the inner contour lines of the full rims may be adapted to different lens shapes, so that any of numerous different lens shapes may be chosen, provided that the length of the circumference of these lens shapes is the same. Hence the central piece now predetermines not the lens shape, i.e., the shape of the circumferential line, but rather the length of the circumferential line. In the course of producing a pair of eyeglasses using the central piece according to the present invention, the two lenses with the chosen lens shape are inserted into the full rims, whereupon the lenses impress their shape upon the rims. The central piece according to the present invention thus makes it possible to use the same central piece to produce eyeglasses with different lens shapes. Hence with the central piece according to the present invention there is no need to produce, for each desired lens shape, a central piece exclusively suited for that lens shape.
Since the full rims in the central piece according to the present invention are flexible—in other words, they have low inherent rigidity and oppose only a low resistance to the action of forces from outside—provision is made for the full rims to be stretched around the lenses, and thus they fit against the edges of the lenses under the action of a prestress, and are held in their intended position by these edges. For this purpose, the central piece according to the present invention is combined with lenses the length of whose circumferential line is somewhat greater than the length of the inner contour line of the full rims, for example by 3%. Thus on inserting the lens into the associated full rim, the full rim is elongated in the direction of its circumference. According to the present invention, the band constituting each full rim is elastic, so that this elongation can take place within the elastic range and the corresponding elastic stresses are lastingly maintained.
Furthermore, the band constituting each full rim is configured in a closed shape, according to the present invention. This means that the band, and thus the full rim, represents an uninterrupted ring without joints or the like, so that the tensile forces in the circumferential direction, generated due to the prestress, are compensated within the band or full rim, and do not need to be absorbed by elements other than the full rim itself. The cohesion of the full rim is thus fully ensured by the closed configuration of the band. Neither the bridge nor the endpiece arranged on the full rim needs to provide for the cohesion of the full rim. The bridge and endpieces are thus relieved of the tensile stresses prevailing within the full rim due to its prestressing. The closed configuration of the band makes it superfluous to provide means for closing the full rim, such as for example are applied in metal full-rim frames, in the form of so-called “closing assemblies.” Moreover, because of the closed configuration of the band, the central piece according to the present invention obviates the need for anchoring mechanisms, such as are necessary in half-rim fr
Graybeal Jackson Haley LLP
Hemaris GmbH
Mai Huy
LandOfFree
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