Method of designing progressive refractive power lens, and lens set

Patent metadata

Field	Value
Publication number	US-10401649-B2
Application number	US-201615576262-A
Country	US
Kind code	B2
Filing date	May 26, 2016
Priority date	May 26, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

When an addition power at a position corresponding to a fitting point within a prescription addition power is greater than a target addition power set according to a target distance, the target addition power is set as an addition power between a progression-start point and a progression-end point on a principal meridian, and in addition the average gradient of an addition power between the progression-start point and the fitting point is set to differ from an average gradient of an addition power between the fitting point and the progression-end point. When the addition power at the position corresponding to the fitting point within the prescription addition power is equal to or smaller than the target addition power, a gradient of the addition power is made constant in a partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.

First claim

The invention claimed is:

1. A method of designing a progressive power lens in which: an intermediate region where an addition power continuously changes is provided between a first region for providing a first power and a second region for providing a second power; a principal meridian is provided in the first region, the intermediate region and the second region, so that the principal meridian passes through a progression-start point at which the change in the addition power starts and a progression-end point at which the change in the addition power ends; a prescription addition power is set based on the difference between the first power and the second power; and a fitting point is set at a position between the progression-start point and the progression-end point, along an extended line of a portion of the principal meridian that passes through the first region, wherein
when an addition power at a position corresponding to the fitting point within the prescription addition power is greater than a target addition power which is set according to a target distance, the target addition power is set as an addition power between the progression-start point and the progression-end point on the principal meridian, and in addition, an average gradient of an addition power between the progression-start point and the fitting point is set to differ from an average gradient of an addition power between the fitting point and the progression-end point, and
when the addition power at the position corresponding to the fitting point within the prescription addition power is equal to or smaller than the target addition power, a gradient of the addition power is made constant in a partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.

2. The method of designing a progressive power lens according to claim 1 , wherein
when d represents the target distance, A represents a dimension between the progression-start point and the fitting point along the extended line, B represents a dimension between the fitting point and the progression-end point along the extended line, and ADD represents the prescription addition power,
in the case of (1/d)<{A/(A+B)}×ADD,
the target addition power is set as the addition power between the progression-start point and the progression-end point on the principal meridian, and in addition the average gradient of the addition power between the progression-start point and the fitting point is set to differ from the average gradient of the addition power between the fitting point and the progression-end point, and
in the case of (1/d)≥{A/(A+B)}×ADD,
the gradient of the addition power is made constant in the partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.

3. The method of designing a progressive power lens according to claim 1 , comprising:
a first step of setting the target addition power according to the target distance;
a second step of determining whether the addition power at the position corresponding to the fitting point within the prescription addition power is greater than the target addition power; and
a third step of setting the addition power between the progression-start point and the progression-end point on the principal meridian based on a determination result in the second step, wherein
in the third step, when the addition power at the position corresponding to the fitting point within the prescription addition power is greater than the target addition power which is set according to the target distance, the target addition power is set as the addition power between the progression-start point and the progression-end point on the principal meridian, and in addition the average gradient of the addition power between the progression-start point and the fitting point is set to differ from the average gradient of the addition power between the fitting point and the progression-end point, and
when the addition power at the position corresponding to the fitting point within the prescription addition power is equal to or smaller than the target addition power, the gradient of the addition power is made constant in the partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.

4. A lens set that is a set of progressive power lenses in each of which: an intermediate region where an addition power continuously changes is provided between a first region for providing a first power and a second region for providing a second power; a principal meridian is provided in the first region, the intermediate region, and the second region, so that the principal meridian passes through a progression-start point at which the change in the addition power starts and a progression-end point at which the change in the addition power ends; a prescription addition power is set based on the difference between the first power and the second power; and a fitting point is set at a position between the progression-start point and the progression-end point, along an extended line of a portion of the principal meridian that passes through the first region, the lens set satisfying conditions that: the first region having different first powers can be selected; a plurality of prescription addition powers can be selected for the first region having the same first power; refractive indexes of materials are the same; and a design concept is consistent among respective progressive power lenses, wherein
the lens set comprises: a first lens in which an addition power at a position corresponding to the fitting point within the prescription addition power is greater than a target addition power which is set according to a target distance; and a second lens in which an addition power at the position corresponding to the fitting point within the prescription addition power is equal to or smaller than the target addition power, wherein
in the first lens, the target addition power is set as an addition power between the progression-start point and the progression-end point on the principal meridian, and in addition an average gradient of an addition power between the progression-start point and the fitting point is set to differ from an average gradient of an addition power between the fitting point and the progression-end point, and
in the second lens, a gradient of an addition power is made constant in a partial region including at least the fitting point between the progression-start point and the progression-end point on the principal meridian.

Assignees

• Hoya Lens Thailand Ltd
• Asami Hiroshi
• Ito Ayumu

Inventors

• Asami Hiroshi
• Ito Ayumu

Classifications

• G02C7/025

  considering parameters of the viewed object · CPC title

• G02C7/065 Primary

  Properties on the principal line · CPC title

• G02C7/06

  bifocal; multifocal {; progressive (G02C7/041 takes precedence)} · CPC title

• G02C7/061

  Spectacle lenses with progressively varying focal power · CPC title

• G02C7/028

  Special mathematical design techniques · CPC title