JPS6237209Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic multifocal eyeglass lens characterized in that the inner corner of the rising portion of the small beads is filled into an arc shape or an inclined surface.

Conventional plastic bifocal eyeglass lenses have a planar shape as shown in Figures 1 and 2, a section 1c in the cross section as shown in Figure 3, and a planar shape as shown in Figure 4 as shown in Figure 5. As shown in section 2c of the cross-sectional shape, the inner corner of the rising portion of the small beads rose sharply. For this reason, when manufacturing plastic lenses, microcracks are likely to occur inside the rising portions of the beads due to stress concentration during curing and shrinkage and during mold release.

These microcracks then grow into larger cracks due to the tightening force applied when putting the lens into the frame, rendering the lens defective.

In addition, in the glass mold for manufacturing lenses, the portion corresponding to the corner of the rising part of the small beads is shown in Fig. 6 1e.
Since it has a sharp ridgeline as shown in FIG. 7, 2e, it is easily chipped during handling, and also has the disadvantage that it is easily chipped during curing and shrinkage during lens manufacturing and during mold release.

The present invention is intended to eliminate the above-mentioned drawbacks, and its purpose is to prevent the occurrence of microcracks at the inner corner of the rising portion of lens beads during lens manufacturing, and to prevent the growth of the microcracks when the lens is inserted into a frame. This is to prevent cracks due to
Another object of the present invention is to make the ridgeline portion corresponding to the corner of the raised portion of the small beads of the lens in a glass mold for lens manufacturing less likely to be chipped during handling and lens manufacturing.

Hereinafter, the present invention will be explained in detail based on examples.

Figures 8 to 13 show embodiments of the present invention;
9 are enlarged cross-sectional views of the raised small beads of the planar bifocal lens as shown in FIGS. 1 and 2, and FIGS. FIG. 3 is an enlarged cross-sectional view of a planar bifocal small bead rising portion. The rising corner is the 8th
0.1~0.3mmR at the maximum part as shown in Figure and Figure 10
Add a fillet to the slope, or as shown in Figures 9 and 11, make sure that the width W of the slope is 0.1 to 0.4 mm at its maximum.
This is to add fillets diagonally.

The fillets should be added so that the fillet is the largest at the part where the height of the rising part is the greatest, and the fillet is the smallest at the part where the height is the smallest.

If the planar shape is as shown in Figures 1 and 2, the 12th
As shown in Figures and Figure 13, add the largest fillet to the center of the ball, and minimize at both ends.

If the planar shape is as shown in Fig. 4, Fig. 14, Fig. 1
Add the largest fillet to both ends of the small ball as shown in Figure 5.
Minimize in the center.

If the amount of filleting is too small, the effect on alleviating stress concentration will be weak, and if it is too large, the boundary of the small bead part will be clearly visible as a spectacle lens, so the above amount is appropriate.

In addition, the glass mold for manufacturing these eyeglass lenses has a portion corresponding to the corner of the raised small bead of the lens as shown in FIG. 16 3d, FIG. 17 4d, FIG. 18 5d, and FIG. 19 6d. , Round the ridgeline to 0.1~0.3mmR at the maximum part, or W is 0.1~0.4
It is chamfered so that it is mm.

In this embodiment, a bifocal eyeglass lens has been described, but trifocal and other multifocal lenses can be applied in exactly the same manner and are included in the scope of the present invention.

The above-described invention can prevent cracks during lens manufacturing and framing, and greatly improve the life of the mold for lens manufacturing, thereby greatly contributing to cost reduction.

[Brief explanation of the drawing]

1 and 2 are examples of the planar shape of a plastic bifocal lens, and FIG. 3 is a cross section taken along the line AA in FIGS. 1 and 2, showing the conventional shape, and 1a is the base portion , 1b is a small bead portion, and 1c is a corner of a small bead rising portion. FIG. 4 shows another example of the planar shape, and FIG. 5 is a cross section taken along line B-B in FIG. 4, showing the conventional shape.
2b is a small ball, and 2c is a small ball rising corner. FIG. 6 shows a glass mold for manufacturing lenses such as those shown in FIGS. 1, 2, and 3, and 1e is a ridgeline corresponding to the corner of the rising portion of the small beads of the lens. FIG. 7 shows a glass mold for producing lenses like those shown in FIGS. 4 and 5, and 2e is a ridgeline corresponding to the corner of the rising part of the small beads of the lens. FIGS. 8 to 11 show cross-sectional shapes of lenses according to the present invention, in which the corners of the raised portions of the small beads are filled. FIGS. 12 to 15 are perspective views of the lens according to the present invention, in which the fillet is maximized at the portion where the raised height of the bead portion is maximum, and is minimized at the portion where it is minimum. 16 to 19 show cross-sectional shapes of glass molds for manufacturing lenses according to the present invention, in which portions corresponding to the rising corners of the lenses are rounded or chamfered.

Claims (1)

[Scope of utility model registration request] In plastic multifocal eyeglass lenses, the inner corner of the rising part of the small bead is filled with R or slope, and the amount of fillet is maximized at the part where the rising height is maximum, and the amount is 0.1 at the maximum part. A spectacle lens characterized by having a radius of ~0.3 mm or a slope width of 0.1 to 0.4 mm.