Method for Manufacturing Bifocal Lens

Abstract

This invention is to provide an inexpensive lens can be worn without attention to the existence of the addition power segment of conventional polarizing lens, it and a bench lens are formed integrally on the rear surface of a polarizing member 6. The present inventors constituent a polarizing member 9 by sandwiching poly vinyl alcohol 3 as a polarizing film with poly carbonate 2 whose both surfaces are stretched, and mold resin 2′ on the rear side of the polarizing member, and arrange an addition power segment 8 integrally on the rear surface, make the molded resin poly carbonate sandwiches the polarizing film. The top and the bottom of this member are cut as FIGs. to form lens at low costs, and the adhesion among respective resins is increased, and to secure the impact resistance and it is possible to create a lens without detachment because of same resin.

Description

BACKGROUND OF THE INVENTION[0001]1. Technical Field[0002]This invention relates to polarized lens of multifocal.[0003]2. Description of the Related Art[0004]Polarizing lenses have their effect to prevent reflected light from going into the eye, and in particular they prevent reflected light from water surface, snow surface, and road surface, and their need is increasing in sports and other daily living. Further, since the demand for these polarizing lenses is expanding in senior generation, the demand for multifocal polarizing lenses is increasing. With regard to the multifocal plastic lens, there has not so far been a low-cost lens that has both durability and impact resistance.[0005]Further, an addition power segment for multifocus has been manufactured of resin different from that of a bench lens, or has been arranged on the surface of a lens in many cases. When the addition power segment is arranged on the front surface side, it shows up, and the polarizing member must be arrang...

AI Technical Summary

Benefits of technology

The present invention provides an affordable lens that can be worn without noticing the addition power segment of conventional polarizing lens, even in senior generation where demand is increasing. The lens has both durability and impact resistance. The invention includes a polarizing member with an addition power segment integrated on the rear surface. The lens is made using a resin called poly carbonate, which is cost-effective. The lens has a reduced deformation and improved impact resistance. The addition power segment is not visible when sunglasses are put on, which makes it more acceptable to users. The invention also includes a method for reducing lens deformation during molding. Overall, the invention provides a better bifocal lens with improved performance.

Problems solved by technology

When the addition power segment is arranged on the front surface side, it shows up, and the polarizing member must be arranged along the shape of the addition power segment, and air gets in between film and mold during molding and the degree of the addition power segment becomes uneven, and other failure occur in its manufacture, which has been a problem in the prior art.

Furthermore, conventionally the addition power segment has been manufactured separately from the bench lens and attached to the bench lens in many cases, however, the addition power segment is as extremely thin as around 0.2 mm, and it may cut the hand of a worker in attachment work, which has been another problem in the prior art.

Moreover, in the multitiered constituent of the polarizing member, resin expanding to both the polarizing film and sandwich resin, however, studies have not been made on the adhesion compatibility between the stretched resin and the polarizing film, further the combination and expansion of resin of constituent member as the bench lens heretofore.

And, the constituent resin of this polarizing member, or the bench lens molded resin and the molded resin of the addition power segment are generally formed as separate resin, in order to have different refraction index, and accordingly, detachment and durability problem, expensive lens cost may be caused, which has been still another problem in the prior art.

Further, the polarizing film itself is extremely expensive.

Images