Progressive Lens Intermediate Zone for Ground Obstacle Safety
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Solution Overview
Problem
Conventional progressive lenses do not provide clear vision of objects at intermediate distances, particularly on the ground, leading to discomfort and increased risk of falls when navigating stairs or obstacles, as they require head movement to maintain focus.
Innovation Solution
A progressive lens with an additional intermediate vision zone below the near-vision zone, featuring an optical power addition of at least 2.0 diopters and an optical power increase threshold near the fitting cross, allowing clear viewing of objects at 35 degrees below the horizontal, thereby enabling safe posture adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional progressive lenses are used with only far-vision and near-vision zones, then the lens structure remains simple, but clear vision of objects at intermediate distances (particularly on the ground) is not provided, requiring head movement and increasing discomfort and fall risk
Solution Approach 1:
The lens is divided into four distinct functional zones: a far-vision zone in the upper part, a near-vision zone in the lower part, and two additional intermediate-vision zones positioned between them. This segmentation allows each zone to provide optimized vision for specific distance ranges, with the intermediate zones specifically addressing the safety issue of viewing ground-level obstacles without requiring head movement.
2Reliability
If the optical power varies continuously between far-vision and near-vision zones, then the transition is smooth, but the intermediate zone provides insufficient vision clarity for objects at 35 degrees below horizontal
Solution Approach 1:
The lens applies local quality by providing different optical characteristics in different zones. The intermediate-vision zones are specifically designed with optical power ranges and additions (0.5 to 2.0 diopters) optimized for viewing objects at intermediate distances and angles (including 35 degrees below horizontal), while maintaining smooth transitions to adjacent zones. This localized optimization ensures clear vision of ground obstacles without compromising overall visual comfort.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lens provides clear and comfortable vision of obstacles on the ground without requiring head movement, enhancing safety when encountering stairs or obstacles by maintaining a clear view of the ground without visual fatigue.
Implementation Method 1
a progressive lens has an optical power which varies between different points thereof, so that the correction of the visual defect which is provided by the lens is adapted as a function of the distance of an object which is viewed by the wearer
Data Source
AI summary
A progressive lens for ophthalmic spectacles has an additional zone for intermediate vision. This additional zone is located beneath a near-vision zone. It enables objects located at a distance of between 1.0 and 1.5 meters, in a direction inclined at about 35 degrees to a line of sight passing through a cross mark (CM) on the lens, to be seen clearly. To achieve this, the optical power progression between a far-vision point (FV) and a near-vision point (NV) of said lens has a power-increase threshold which is located approximately at the cross mark.