US 4,730,924 AGranted

Lens meter and method of measurement of progressive multifocal lens using the same

AssigneeTokyo Kogaku Kikai Kabushiki Kaisha

InventorsHenri Allard, Robert Drummond, Charles P. Villeneuve, Yukio Ikezawa

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Abstract

Lens meter and method of measurement of progressive multifocal lens using the same which is able to set the amount of movement of the lens and to simply position a far- or near-distance refraction characteristics-measuring portion of a progressive multifocal lens. In accordance with the method the optical center of a lens is first found from measurement employing the lens and using the optical center as point of origin, the lens is moved by a distance up to the far-distance refraction characteristics measuring portion and the near-distance refraction characteristics measuring portion of the lens mentioned by the lens manufacturer, so as to effect alignment with the measurement optical axis of the lens meter, thereby measuring the refraction characteristics of each measuring portion.

Claims14

Dependent claims

A method of measuring, by the use of a lens meter, the refraction characteristics of a progressive multifocal lens to be examined, comprising:

a first step of optically aligning the optical center of the lens with a measurement optical axis of said lens meter;
a second step of moving the lens in such a manner that the far-distance refraction characteristics measuring portion of the lens will be aligned with said measurement optical axis by geographically moving said optical center by a predetermined distance of movement for the far-distance using said measurement optical axis as a point of origin;
a third step of measuring the far-distance refraction characteristics of the lens in said far-distance refraction characteristics measuring portion obtained in said second step;
a fourth step of moving the lens in such a manner that said optical center will be geographically moved by a predetermined distance of movement for near-distance using said measurement optical axis as a point of origin;
a fifth step of setting the near-distance refraction characteristics measuring portion of the lens so as to be aligned with said measurement optical axis in such manner that said optical center of the lens is geographically moved toward the nose side thereof by a predetermined amount of nose-side movement distance using the moved position obtained in said fourth step as a point of origin, or that the moved position obtained in said fourth step allows a maximum value to be obtained for an additional degree of the near distance calculated from a measured value at the time when said optical center of the lens is moved to the nose-side using the moved position obtained in said fourth step as a point of origin;
and
a sixth step of measuring the near-distance refraction characteristics of said near-distance refraction characteristics measuring portion set in said fifth step.

4 more elements

A lens meter for measuring the refraction characteristics of a progressive multifocal lens to be examined having a lens mounting means for mounting the lens fitted into an eyeglasses frame, a measuring means for measuring the refraction characteristics of the lens, a lens table having a table surface for abutting the lens frame of the eyeglasses frame and for restricting the vertical position of the lens within a plane substantially vertical to the optical axis of said measuring means, and a lens table moving means for moving said lens table in such a manner as to change an interval between said table surface and said optical axis, characterized in that said lens meter has a vertical movement amount setting means for setting an amount of said vertical movement of the lens, and said lens vertical movement amount setting means is arranged such that its point of origin can be changed independently from the movement of said lens table.

Dependencies are inferred from the claim text.