Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1997-06-03
2000-02-01
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
351177, G02C 706
Patent
active
060194707
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a progressive multifocal lens for correction of vision, and a manufacturing method of an eyeglass lens and a progressive multifocal lens using it.
DESCRIPTION OF RELATED ART
A progressive multifocal lens is a lens comprising two field sections having different refractive power, and a field section whereby the refractive power changes progressively between these. It is superior in external appearance, as there are no boundaries in these field sections. Furthermore, fields having different refractive powers in a single lens can be obtained. Therefore, it is used widely as an eyeglass lens having vision correcting functions for aging vision and the like.
FIGS. 25(a) and 25(b) shows the general structure of a conventional progressive multifocal lens used widely as an eyeglass lens. This progressive multifocal lens 1 is provided on the upper side with a distance-vision region 11 being a field section for seeing objects at a far distance. A field section for seeing objects at a near distance having a different refractive power from the distance-vision region 11 is provided on the lower side as a near-vision region 12. Also, the distance-vision region 11 and near-vision region 12 are joined smoothly by a progressive region 13 being a field section having a refractive power that changes continuously for seeing objects at an intermediate distance between the far distance and the near distance.
In a single lens 1 used for an eyeglass, all the capabilities required for an eyeglass, for example, a vertex power matching the user's prescription, a cylinder power for correcting astigmatism, a join power for correcting aging vision, and furthermore a prism power for correcting skew, must be provided by the two surfaces being a refractive surface 2 on the side of the eye and a refractive surface 3 on the side of the observed object. Therefore, in a conventional progressive multifocal lens 1, as shown in FIG. 25, a progressive refractive surface 5 providing a refractive power that changes continuously in order to compose the distance-vision region 11, near-vision region 12, and progressive region 13, is formed on the refractive surface 3 on the side of the object. The refractive surface 2 is used as a refractive surface, or the like, for correcting astigmatism as described above.
FIG. 26 shows the astigmatism obtained with the conventional progressive multifocal lens 1, and FIG. 27 shows the summary distribution of the z coordinates of the progressive refractive surface 5 formed on the refractive surface 3 of the conventional progressive multifocal lens on the side of the object. On the refractive surface 3, the plane surface is represented as the xy coordinates, and the direction showing the thickness of the lens perpendicular to this xy plane is represented as the z coordinates. There is no particular need to define the direction of the x and y coordinates, however, in the following explanation the up-and-down direction when the lens 1 is worn as an eyeglass lens is the y coordinate, and the left-right direction is the x coordinate.
Because the progressive refractive face 5 is non-spherical so as to change continuously the refractive power, the curvature changes according to each region of the surface. Consequently, as understood from FIG. 26, even in a progressive multifocal lens 1 not for correction of astigmatism having the surface 2 on the side of the eye as a spherical surface, if a progressive refractive surface 5 is introduced on the surface 3 on the side of the object, an astigmatic aberration is generated on the surface by the difference in curvature in the x direction and the y direction. This astigmatic aberration is represented in diopter (D) units, and the drawing of astigmatic aberration shown in FIG. 26 is a drawing having the regions of specific diopters connected by contour lines.
A user of an eyeglass not having astigmatism can obtain clear vision without perceiving so much the fading of an image if the astigmatic aberration appearing in the len
REFERENCES:
patent: 4606622 (1986-08-01), Fueter et al.
patent: 4950057 (1990-08-01), Shirayanagi
patent: 5137343 (1992-08-01), Kelch et al.
Kato Kazutoshi
Mukaiyama Hiroyuki
Seiko Epson Corporation
Sugarman Scott J.
LandOfFree
Progressive multifocal lens and manufacturing method of eyeglass does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Progressive multifocal lens and manufacturing method of eyeglass, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Progressive multifocal lens and manufacturing method of eyeglass will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-932249