Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
1999-04-16
2001-02-27
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S169000
Reexamination Certificate
active
06193370
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing spectacle lenses and, in particular, progressive power spectacle lenses.
2. Description of the Related Art
As shown in
FIG. 7
, a conventional progressive power spectacle lens generally includes: a distance portion
11
, which has a dioptric power for distance vision; a near portion
12
, which has a dioptric power for near vision; an intermediate portion
13
, which has a dioptric power at intermediate ranges between distance vision and near vision; and peripheral portions, i.e., right and left side portions
14
and
15
.
A main meridian
16
can be defined on the spectacle lens, through which the line of sight of the lens-wearer frequently moves from near vision to distance vision (or vice versa). The main meridian
16
passes through the distance portion
11
, the intermediate portion
13
and the near portion
12
, approximately along the vertical center line of the lens. The lens is required to be designed so that aberrations along the main meridian
16
are well-correct ed. When the lens-wearer views an object at a near distance, the main meridian
16
approaches the nose (of the lens-wearer) because the line of sight of each eye moves inward (towards the nose). The horizontal displacement of the main meridian
16
towards the nose (i.e., the horizontal distance ‘H’ in
FIG. 7
) in the near portion is known as the amount of “inset”.
In a conventional progressive power spectacle lens, the amount of inset is generally determined in the range of approximately 2.5 mm through 3.0 mm regardless of the dioptric power of the lens. However, changing the amount of inset of the progressive power spectacle lens in accordance with the dioptric power of the lens has been recently proposed.
FIGS. 8 and 9
show the principle of the necessity of changing the amount of inset in accordance with the dioptric power of the lens. In
Figs.8 and 9
, right and left eyeball are designated by “RE” and “LE”, respectively, and the amount of inset of each lens is designated by “H”.
FIG. 8
shows the case when viewing an object
17
at a near distance through a pair of spectacle lenses each having a negative dioptric power. Right and left lines of sight
18
and
19
through the lenses are shown by solid lines, while right and left lines of sight
18
and
19
without the lenses are shown by dotted lines. As can be seen in
FIG. 8
, the lines of sight
18
and
19
are bent through the lenses toward each other.
FIG. 9
shows an example of viewing an object
17
at a near distance through a pair of spectacle lenses each having positive dioptric power. As can be seen in
FIG. 9
, the lines of sight
18
and
19
are bent through the lenses in opposite directions away from each other. Considering the effect the lenses have, in order for the lens-wearer to be able to view an object at a near distance naturally with both eyes, it can be appreciated in the case of the negative lenses that the amount of inset H should be reduced, whereas in the case of the positive lenses that the amount of inset H should be increased.
Accordingly, the dioptric power (the distance portion vertex power and the addition power) is one of the factors for determining the optimum amount of inset. However, the inventor of the present invention has found that conventional progressive power spectacle lenses are manufactured so that the amount of inset is determined only in accordance with the dioptric power without taking into account individual differences in wearing state of the lenswearers. wearers. Hence, there is still room for further improvement of progressive power spectacle lenses.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a method of manufacturing progressive power spectacle lenses wherein the amount of inset is determined in accordance with the individual fitting condition data of a lens-wearer so as to provide a pair of progressive power spectacle lenses through which an adequate clear view area for both eyes can be obtained for near vision.
To achieve the above-mentioned object, according to an aspect of the present invention, there is provided a method of manufacturing progressive power spectacle lenses, including preparing individual fitting condition data for a lens-wearer, and determining an amount of inset in accordance with the individual fitting condition data.
Preferably, the individual fitting condition data includes data regarding the object distance for near vision, the pupillary distance between both eyes for distance vision, the distance from the point-of-rotation of each eyeball of the lens-wearer to each the spectacle lens, the pantoscopic angle (tilt) of the spectacle lenses when fitted to the lens-wearer.
Preferably, the determining step includes determining a difference between an optimum amount of inset and an amount of inset according to a pre-determined standard.
Preferably, the manufacturing method includes: designing the shape of a progressive surface so that the amount of inset becomes identical to an optimum amount of inset determined in accordance with the. individual fitting condition data; and forming the progressive surface having the designed shape on the progressive side of a lens blank.
Preferably, the manufacturing method includes: preparing a progressive power semi-finished lens blank which is provided on a progressive side thereof with a progressive surface having an amount of inset according to a pre-determined standard; rotating the progressive power semi-finished lens blank to have a desired amount of inset; and grinding a non-progressive side of the progressive power semi-finished lens blank.
Preferably, the manufacturing method includes: preparing a progressive power semi-finished lens blank which is provided on a progressive side thereof with a progressive surface having an amount of inset according to a pre-determi ned standard; displacing a fitting point on the progressive power semi-finished lens blank to have a desired amount of inset; and grinding a non-progressive side of the progressive power semi-finished lens blank.
Preferably, the manufacturing method includes: preparing a progressive power semi-finished lens blank which is provided on a progressive side thereof with a progressive surface having an amount of inset according to a pre-determi ned standard; rotating the progressive power semi-finished lens blank while displacing a fitting point on the progressive power semi-finished lens blank to have a desired amount of inset; and grinding a non-progressive side of the progressive power semi-finished lens blank.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 10-107965 (filed on Apr. 17, 1998) which is expressly incorporated herein by reference in its entirety.
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Asahi Kogaku Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Sugarman Scott J.
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