Error-Tolerant Progressive Lens Design via Refraction Deviation

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Solution Overview

Problem

Conventional progressive spectacle glasses are sensitive to refraction errors, particularly positive refraction errors, which affect optical imaging characteristics, especially when the pupil opens, leading to issues like fogginess and reduced visual acuity, especially in non-ideal light conditions.

Innovation Solution

A method of producing progressive spectacle glasses by calculating a negative desired refraction deviation in the far reference point and a positive deviation in the near reference point, optimizing the refraction values along the main line to reduce sensitivity to small refraction errors and improve optical imaging characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional progressive spectacle glasses are designed with standard refraction values, then the optical imaging characteristics are acceptable under ideal conditions, but the glasses become sensitive to positive refraction errors when the pupil opens, causing fogginess and reduced visual acuity

Engineering Contradiction:

Improveoptical imaging characteristicsVSAvoidsensitivity to refraction errors

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by intentionally introducing a negative refraction deviation (e.g., -0.125 D) in the far reference point and a positive refraction deviation in the near reference point during the lens design phase. This pre-compensation counteracts the expected positive refraction errors that occur when the pupil opens, thereby preventing fogginess and maintaining visual acuity under varying light conditions.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent implements parameter changes by modifying the refraction values at specific reference points (far reference point and near reference point) while maintaining the overall progressive lens structure. By adjusting these specific parameters, the lens achieves reduced sensitivity to refraction errors without fundamentally changing the progressive addition lens concept.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If the refraction value starts to rise directly below the far reference point as customary, then the progression zone provides adequate depth of focus, but the main viewing direction experiences fogginess that can only be compensated under best light conditions

Engineering Contradiction:

Improvedepth of focusVSAvoidvisual acuity in main viewing direction

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the refraction value adjustments at different locations within the lens. Specifically, a negative refraction deviation is applied in the far reference point area while a positive deviation is applied in the near reference point area, creating location-specific optical properties that simultaneously maintain depth of focus and improve visual acuity in the main viewing direction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional approach by introducing a negative refraction deviation in the far reference point instead of the customary positive or neutral value. This inversion allows the refraction value to rise more gradually below the far reference point, reducing fogginess in the main viewing direction while preserving adequate depth of focus through the progression zone.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If progressive spectacle glasses are designed to be less sensitive to refraction errors, then optical imaging characteristics improve, but the lens design becomes more complex with multiple reference point adjustments

Engineering Contradiction:

Improveoptical imaging characteristicsVSAvoidlens design complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial action by making refraction adjustments only at specific critical reference points (far reference point and near reference point) rather than throughout the entire lens. This selective approach reduces sensitivity to refraction errors while avoiding the complexity of redesigning the entire progressive lens structure.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7771047B2Error-tolerant progressive glass design

Publication Date: 2010.08.10 RODENSTOCK GMBH

AI summary

A method of producing a progressive spectacle glass by defining an ordering value for the average use value in the far reference point of the progressive spectacle glass, calculating the progressive spectacle glass while taking into account a calculation value of the average use value in the far reference point, the calculation value having a negative desired refraction deviation between 0.03 dpt and 0.2 dpt with respect to the ordering value in the far reference point, and producing the calculated progressive spectacle glass.